Synthesis and structural characterization of ferrocene phosphines modified with polar pendants and their palladium(II) complexes. Part I: N-aminocarbonyl and N-acyl phosphinoferrocene carboxamides

Journal of Organometallic Chemistry xxx (2016) 1e15

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Synthesis and structural characterization of ferrocene phosphines modified with polar pendants and their palladium(II) complexes. Part I: N-aminocarbonyl and N-acyl phosphinoferrocene carboxamides e tova , Ivana Císarova , Petr St pni Hana Charva cka* Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Prague, Czech Republic

a r t i c l e i n f o

a b s t r a c t

Article history: Received 14 December 2015 Received in revised form 22 February 2016 Accepted 25 February 2016 Available online xxx Dedicated to Professor Heinrich Lang on the occasion of his 60th birthday.

Acylation of 10 -(diphenylphosphino)-1-(aminocarbonyl)ferrocene, Ph2PfcCONH2 (1; fc ¼ ferrocene-1,10 diyl), afforded a series of acyl-ureas including Ph2PfcCONHCONHEt (1a), Ph2PfcCONHCONHPh (1b), and Ph2PfcCONHCONMe2 (1c) as well as the acetyl derivative Ph2PfcCONHAc (1d). Compounds 1a-d were converted to the corresponding phosphine oxides (2a-d) and further examined as ligands in Pd(II) complexes. The reactions of 1a-d with [PdCl2(cod)] (cod ¼ cycloocta-1,5-diene) at a 2:1 ligand-to-metal ratio gave the bis(phosphine) complexes [PdCl2(L-kP)2] (3a-d; L ¼ 1a-d), whereas the reactions with [Pd(LNC)Cl]2 (LNC ¼ [2-(dimethylamino-kN)methyl]phenyl-kC1) produced the bridge-cleavage products, [PdCl(LNC)(L-kP)] (4a-d). Removal of the Pd-bound halide from 4a-d with Ag[SbF6] furnished the corresponding cationic bis-chelate complexes [Pd(LNC)(L-k2O,P)][SbF6] (5a-d). All compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. The crystal structures of 1a, 2a-c, 3a$2CHCl3, 3b$2CHCl3, 3d$2CHCl3, 4a$3CHCl3, 4b$2.5CHCl3, 5a$CHCl3, 5b$2CH2Cl2, and 5d were determined by single-crystal X-ray diffraction analysis, which revealed that the hydrogen-bonded arrays formed in the crystals of free ligands are often preserved in the structures of their complexes. © 2016 Elsevier B.V. All rights reserved.

Keywords: Ferrocene ligands Phosphines Amides Ureas Palladium complexes Structure elucidation

1. Introduction Phosphinocarboxylic amides are attractive ligands for coordination chemistry and catalysis [1]. Although a vast number of these specific hybrid phosphines [2] differing in both the phosphine and amide parts of their molecules has been reported and utilized in various fields [1], little attention has been given to compounds with extended amide pendants. For instance, donors whose amide moieties are expanded to acylurea groups by an attached aminocarbonyl substituent typically comprise cyclic acylurea units such in 6-(diphenylphosphino)uracil (A in Scheme 1) [3]. Other examples include phosphine-tagged uracil nucleosides and oligonucleotides [4] and a phosphine-modified barbiturate employed in selfassembled catalysts for Rh-catalyzed hydroacylation and hydroarylation of terminal olefins (B in Scheme 1) [5].

* Corresponding author. e pni E-mail address: [email protected] (P. St cka).

Given our continuing interest in the coordination and catalytic chemistry of phosphinoferrocene carboxamides [6] and particularly in view of the favorable catalytic properties of phosphinoferrocene amido-ureas (C in Scheme 2) [7] and phosphinoferrocene ureas (D in Scheme 2) [8], we have decided to prepare and study phosphinoferrocene amides bearing aminocarbonyl groups at the amide nitrogen (Scheme 2, bottom). It should be noted that acylureas without phosphine substituents are not unprecedented in ferrocene chemistry. A series of ferrocenecarbonyl ureas of the type FcCONHCONHAr (Fc ¼ ferrocenyl) has been prepared by the reaction of ferrocene carboxamide (FcCONH2) with isocyanates ArNCO [9], and compounds of the type FcCONRCONHR were typically isolated from the conventional reactions of ferrocenecarboxylic acid with carbodiimides (RN ] C ] NR) [10], which also led to phosphine-substituted derivatives from ferrocene phosphinocarboxylic acids [11]. In addition, several structurally related compounds were recently obtained by the acylation of uracil, thymine, and 5-fluorouracil with FcCOCl or FcCOOCOOEt [12]. This contribution describes the synthesis and characterization

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Scheme 1. Examples of phosphines possessing cyclic acyl-urea substituents.

Scheme 2.

Scheme 3. Synthesis of compounds 1a-d from amide 1 (LiHMDS ¼ LiN(SiMe3)2).

of phosphinoferrocene donors bearing (aminocarbonyl)amide substituents in the 10 position of the ferrocene unit [13] that are accessible from phosphinoferrocene amide 1 [14], and their palladium(II) complexes. Particular attention is being paid to the crystal structures of these compounds because they possess extended polar moieties suitable for the formation of solid-state assemblies via hydrogen bonding interactions. 2. Results and discussion 2.1. Synthesis of phosphines 1a-d and their corresponding phosphine oxides Compounds 1a-d were obtained via extensions of the amide moiety in the parent compound 1 [14] as shown in Scheme 3. The acylureas 1a and 1b resulted from the reactions of 1 with the respective isocyanates (N.B. the reaction with EtNCO required the presence of LiHMDS), whereas the tertiary urea derivative 1c, which is an isomer of 1a, was prepared by the reaction of in situ deprotonated 1 with N,N-dimethylcarbamoyl chloride. An analogous reaction exploiting acetyl chloride as the acylating agent was used to prepare the diacyl derivative 1d, which was included in the series of prospective ligands for the sake of comparison. Compounds 1a-d were isolated in moderate to good yields as orange amorphous solids that tenaciously retain traces of organic solvents used during column chromatography and were characterized by spectroscopic methods and elemental analysis. In their electrospray ionization (ESI) mass spectra, compounds 1a-d display peaks of the pseudomolecular ions ([M þ Na/K]þ or [M  H]e). The 1 H and 13C NMR spectra of 1a-d exhibit characteristic signals of the phosphinoferrocene moiety and the attached polar pendants [the signals of the C]O groups are observed at dC 152e154 (urea) and 169e172 (amide) in CDCl3], whereas the 31P NMR signals of 1ad are observed at dP z 17.5 ppm, similar to that of the parent amide 1 [14]. Phosphines 1a-d were further converted to the more easily

Scheme 4. Preparation of phosphine oxides 2 by oxidation of 1.

crystallizable phosphine oxides 2a-c by oxidation with hydrogen peroxide in acetone (Scheme 4; Note: compound 2c was isolated as a byproduct during the synthesis of 1c). The oxidation is nicely manifested by shifts of the 31P NMR signals to lower fields (dP in the range ca. 29e31 ppm) and also results in characteristic shifts of the signals due to carbons within the phosphorus-substituted aromatic rings and in an increase in the JPC coupling constants in the 13C NMR spectra [15]. In contrast, the signals of the polar pendants remain practically unaffected by the oxidation of the phosphine moiety (cf. dC 151e155 and 169e172 for the urea and carboxamide C]O groups, respectively, in CDCl3).

2.2. The crystal structures of 1a, 2a, 2b, and 2c The central ferrocene moieties in the structures of 1a, 2a, 2b, and 2c (Figs. 1e3 and Table 1) adopt their regular geometry with marginal variation in the individual FeeC distances (up to ca. 0.05 Å for the ten FeeC distances in one compound) and, consequently, minor tilting of their cyclopentadienyl rings (maximum 4.35(8) for 1a). Geometric parameters describing the attached functional groups do not depart from the usual ranges [16] and compare well

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Fig. 3. PLATON plot of the molecular structure of 2c. Displacement ellipsoids are scaled to the 30% probability level, and the intramolecular N1eH1N/O3]P hydrogen bond is indicated by a dashed line.

Fig. 1. PLATON plot of the molecular structures of 1a (top) and 2a (bottom). Displacement ellipsoids enclose the 30% probability level.

with the values determined previously for the parent compound 1 [14] and analogous amides substituted at the amide nitrogen [17], while the P]O bond distances in the phosphine oxides are similar to those determined for 1,10 -bis(diphenylphosphinyl)ferrocene dihydrate (dppfO2$2H2O, 1.495(2) Å) [18], 10 -(diphenylphosphinyl) ferrocene-1-carboxylic acid [19], or the corresponding alcohol, Ph2P(O)fcCH2OH (fc ¼ ferrocene-1,10 -diyl) [20]. The 1,10 -disubstituted ferrocene units in 1a and 2a-c adopt different conformations [21]. Whereas the ferrocene substituents in 1a and 2c are nearly synclinal eclipsed (compare t angle in Table 1 with the ideal value of 72 ), those in 2a and 2b assume a

Fig. 2. PLATON plot of the molecular structure of 2b showing displacement ellipsoids at the 30% probability level.

conformation exactly halfway between anticlinal eclipsed and antiperiplanar staggered characterized by the t values of 144 and 180 , respectively. This can be accounted for by the formation of hydrogen bonds in the solid state, which also seem to influence the orientation of the amide pendants with respect to their bonding cyclopentadienyl ring. In all four cases, the amide moiety {C11, O1, N1} is rotated from the plane of the ring C(1e5), though to varying extent. The maximum rotation of approximately 31 is observed for the derivative possessing the terminal dimethylamino group, compound 2c, the conformation of which appears to be dictated by the intramolecular N1eH1N/O3]P hydrogen bond (N1/O3 ¼ 2.846(2) Å, angle at H1N ¼ 169 ; see Fig. 3). The same interaction most likely results in a marked twisting of the acylurea moiety in this compound, which is demonstrated by the dihedral angle between the {C11, O1, N1} and {N1, C24, O2, N2} planes of 46.7(2) . In contrast, atoms constituting the acylurea units, {C11, O1, N1, C24, O2, N2}, in all other remaining structurally characterized compoundsd1a, 2a, and 2bdremain coplanar within approximately 0.05 Å, allowing for conjugation in the entire C(O)NHC(O)N moiety. Despite the presence of the polarized P]O group that can serve as a good hydrogen bond acceptor in 2a, the hydrogen bonding interactions in the crystal structures of compounds 1a and 2a are the same (Fig. 4). Both compounds associate into dimers via C24] O2/H1eN1 bonds between molecules laying across the crystallographic inversion centers (O2/N1 ¼ 2.855(2)/2.884(2) Å, angle at H1N ¼ 166/168 for 1a/2a) and also form a relatively shorter, bent intramolecular hydrogen bridges between the terminal NH group and the amide oxygen, C11]O1/H2NeN2 (O1/N2 ¼ 2.654(2)/ 2.620(2) Å, angle at H2N ¼ 134/138 for 1a/2a). The latter interaction, albeit with an unfavorably acute angle at the hydrogen atom, can also be detected in the crystal structure of 2b (O1/N2 ¼ 2.621(5) Å angle at H2N ¼ 115 , Fig. 4). However, the intermolecular association of the individual molecules of 2b occurs

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Table 1 Selected distances and angles for 1a, 2a, 2b, and 2c (in Å and deg).a Parameter

1a

2a

2b

2c

FeeCgC FeeCgP :CpP,CpC

1.6438(6) 1.6422(7) 4.35(8) 79.47(9) e 1.816(1) 1.837(1) 1.842(1) 1.226(2) 1.377(2) 1.401(2) 1.231(2) 1.332(2) 123.0(1) 119.3(1) 123.2(1) 117.5(1) 15.7(2)

1.6539(6) 1.6549(6) 1.41(8) 162.99(9) 1.488(1) 1.790(1) 1.812(1) 1.800(1) 1.230(2) 1.373(2) 1.414(2) 1.231(2) 1.331(2) 123.1(1) 119.4(1) 124.4(1) 116.3(1) 10.0(2)

1.657(2) 1.648(3) 1.4(3) 164.6(3) 1.487(3) 1.785(5) 1.807(5) 1.799(5) 1.231(6) 1.379(6) 1.420(6) 1.212(6) 1.352(7) 123.9(4) 118.5(5) 126.4(5) 115.1(4) 3.9(5)

1.6454(7) 1.6415(7) 0.80(9) 73.1(1) 1.496(1) 1.773(1) 1.800(2) 1.807(2) 1.218(2) 1.379(2) 1.411(2) 1.222(2) 1.350(2) 123.5(1) 121.9(1) 122.7(1) 115.3(1) 30.6(2)

t PeO3 P1eC6 P1eC12 P1eC18 C11eO1 C11eN1 N1eC24 C24eO2 N2eC24 O1eC11eN1 O2eC24eN1 O2eC24eN2 N1eC24eN2 4

a Definitions: CpC and CpP are the amide- and phosphine-substituted cyclopentadienyl rings C(1e5) and C(6e10), respectively. CgC and CgP denote their corresponding centroids. t is the torsion angle C1-CgC-CgP-C6, and 4 is the dihedral angle subtended by the CpC ring and the amide plane {C11, O1, N1}.

via hydrogen bonds between the phosphoryl oxygen and the acylNH group, P]O3/H1NeN1 (O3/N1 ¼ 2.826(5) Å, angle at H1N ¼ 174 ). 2.3. Preparation of Pd(II) complexes with 1a-d The coordination properties of phosphines 1a-d were assessed

Fig. 4. Hydrogen bonds employing the NH protons in the crystal structure of 1a (Note: compound 2a forms an analogous assembly in the solid state, see text) and 2b.

in the following series of Pd(II) complexes: the bis(phosphine) complexes 3 (Scheme 5), the phosphine complexes with an auxiliary 2-[(dimethylamino)methyl]phenyl (LNC) ligand 4, and the cationic bis-chelate complexes 5 resulting from 4 via halogen removal (Scheme 6 below). Complexes of type 3 were obtained by replacement of the pcoordinated diene from [PdCl2(cod)] (cod ¼ cycloocta-1,5-diene) with two equivalents of the respective amido-phosphine. Because crystalline 3a was practically insoluble in all common laboratory solvents, it was synthesized by a reactive diffusion approach. Solutions containing stoichiometric amounts of ligand 1a and [PdCl2(cod)] were allowed to mix slowly by liquid-phase diffusion, and product separation was completed by the addition of diethyl ether to the resulting mixture (as a top layer) to allow slow crystallization. Although the somewhat more soluble complexes 3bd could be prepared in the usual manner, i.e., by reacting [PdCl2(cod)] with the respective phosphine in dichloromethane solution and the subsequent precipitation of the products with hexanes, the generally poor solubility of the bis(phosphine) complexes 3a-d precluded their characterization by solution techniques (especially by NMR spectroscopy). Complexes 4 were obtained upon the addition of a stoichiometric amount of the respective ligand to dimer [(LNC)PdCl]2 (Scheme 6) and were isolated in good to quantitative yields after crystallization from chloroform-hexane or simply by the evaporation of the reaction mixture. In the next step, compounds 4 were converted to bis-chelate complexes 5 by removal of the Pd-bound chloride with one molar equivalent of Ag[SbF6]. The ESI mass spectra of complexes 4 and 5 are dominated by signals of the cations [(LNC)Pd(1)]þ that are either formed by the loss of the chloride ligand or present inherently. The 31P NMR spectra of 4 and 5 show singlet resonances at dP ca. 32.3 (in CDCl3) and at dP ca. 30e31 (in dmso-d6), respectively. The 1H and 13C NMR spectra, particularly the 4JPH and 3JPC coupling constants determined for the signals due to the CH2NMe2 arm of the chelating LNC ligand [14], indicate that complexes 4 and 5 possess a trans-PeN arrangement. This preferred geometry, placing the donors with the strongest trans-influence (phenyl and phosphine) [22] into cis-positions, prevents a possible destabilization of the complex species via transphobia of the two soft donor moieties attached to a soft metal center [23,24]. It is also noteworthy that only the ferrocenebound carbonyl group coordinates to the Pd (II) center in complexes 5, giving rise to a relatively smaller and rigid chelate ring.

Scheme 5. Preparation of bis(phosphine) complexes 3a-d.

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100.27(6)e101.51(6) for 1a). On the other hand, parameters pertaining to the amide pendant change only marginally upon coordination, being affected by hydrogen bond interactions in which these polar groups participate. The complex molecules in the structure 3a$2CHCl3 form the same set of hydrogen bonds as in uncoordinated 1adthe intermolecular C24]O2/H1eN1 bridges around the inversion centers (O2/N1 ¼ 2.870(3) Å, angle at H1N ¼ 170 ) and the intramolecular C11]O1/H2NeN2 hydrogen bonds (O1/N2 ¼ 2.654(3) Å, angle at H2N ¼ 143 ; see Fig. 5b). Because the two equivalent amide moieties present in each complex molecule are directed away from each other and interact with different adjacent molecules, these hydrogen bonds result in the formation of infinite chains in the (0 1 1) direction. Similar supramolecular assemblies can be found in the crystal structures of 3b$2CHCl3 (O2/N1 ¼ 2.818(3) Å, angle at H1N ¼ 171 ; O1/N2 ¼ 2.652(3) Å, angle at H2N ¼ 140 ; base vector (1 1 1)) and 3d$2CHCl3, in which the intermolecular hydrogen bond is naturally absent [O2/N1 ¼ 2.930(3) Å, angle at H1N ¼ 158 ; base vector (0 1 1)]. 2.5. The crystal structures of the Pd(II) complexes with auxiliary [2(dimethylamino)methyl]phenyl ligand

Scheme 6. Synthesis of Pd(II) complexes 4a-d and 5a-d possessing auxiliary 2(dimethylamino)methyl]phenyl chelating ligand.

2.4. The crystal structures of the bis(phosphine) complexes 3a-d Recrystallization of the bis(phosphine) complexes provided Xray quality crystals of 3a$2CHCl3, 3b$2CHCl3, and 3d$2CHCl3. All compounds crystallize with the symmetry of the triclinic space group P1 such that the palladium atoms reside on the crystallographic inversion centers (Figs. 5e7), which renders the half of the complex molecule (and one solvent molecule) crystallographically independent. In the case of 3a$2CHCl3, the chloride ligands appear disordered within the space delimited by the bulky phosphinoferrocene donors and were refined over two positions approximately related by rotation along the PeP0 axis. Disorder is also detected in the structures of 3b$2CHCl3 and 3d$2CHCl3 and affects the solvent molecules, which were numerically removed from the structure model (see Experimental for details). Parameters describing the molecular geometry of these bis(phosphine) complexes are similar in the series and also compare well with those reported for [PdCl2(Ph2PfcCOY-kP)2], where Y ¼ OH [25], NH2 [14], and NHPh [26]. Coordination spheres around the Pd(II) centers in 3a$2CHCl3, 3b$2CHCl3, and 3d$2CHCl3 are ideally planar due to imposed symmetry and have quite similar Pdedonor distances (PdeCl z PdeP). The interligand angles slightly depart from the ideal 90 , which can be attributed to steric reasons (note: the sum of the adjacent ClePdeP and ClePdeP0 angles is exactly 180 for symmetry reasons). In all three cases, the ferrocene substituents assume nearly anticlinal eclipsed conformations (compare parameters t in Table 2 with the ideal value of 144 ), and thus are more distant than in uncoordinated 1a. The tilting of the amide planes with respect to their parent cyclopentadienyl rings is less than 20 (~10e16 ). Comparison with the structural parameters determined for uncoordinated 1a further reveals that the coordination via phosphorus (i.e., replacement of the lone pair with Pd(II) ion) results in a slight yet statistically significant shortening of the PeC bonds and an opening of the CePeC angles (cf. 102.4(1)e105.5(1) for 3a$2CHCl3 and

Two complexes of the type [PdCl(LNC)(L-kP)] (4) possessing Nethyl (4a$3CHCl3) and N-phenyl (4b$2.5CHCl3) terminal substituents were structurally characterized. Similarly to the bis(phosphine) complexes, these compounds crystallize solvated by chlorinated solvents that are at least partly disordered within structural voids between the bulky complex molecules. The structures of the complex molecules in 4a$3CHCl3 and 4b$2.5CHCl3 are shown in Fig. 8, and the relevant geometric parameters are given in Table 3. In general, structural parameters determined for 4a$3CHCl3 and 4b$2.5CHCl3 (also 5a$CHCl3 and 5b$2CH2Cl2; see below) compare well with those reported for analogous complexes with ligand 1 [14] or its N-phenyl analogue [26]. Unlike the bis(phosphine) complexes 3, the coordination environment of the Pd(II) ion in complexes 4 is considerably twisted. The distortion reflects not only the variation in the Pdedonor bond lengths (PdeC < PdeN < PdeP < PdeCl) but also the presence of the five-membered palladacycle with which the two shortest Pddonor bonds are associated. The twisting can be demonstrated by the dihedral angle of the coordination half-planes {Pd, Cl, P} and {Pd, N3, C40} being 16.26(9) for 4a$3CHCl3 and 18.21(8) for 4b$2.5CHCl3. The most acute interligand angle is expectedly found within the metallacycle (N3ePdeC40) and is compensated for by an opening of the adjacent PePdeC40 angle, whereas the other two interligand angles remain close to 90 . The five-membered metallacycle adopts a warped envelope conformation with the N3 atom at the tip position, and the phenylene plane (C(40e45)) appears rotated with respect to the {Pd, N3, C40} plane by 21.4(1) and 20.3(1) in 4a$3CHCl3 and 4b$2.5CHCl3, respectively. The substituents at the ferrocene unit in 4a$3CHCl3 and 4b$2.5CHCl3 assume an intermediate conformation between synclinal eclipsed (ideal value: t ¼ 72 ) and anticlinal staggered (ideal value: t ¼ 108 ), similar to that in uncoordinated 1a. The cyclopentadienyl rings in these complexes are negligibly tilted (tilt angles < 2 ), and the {C11, O1, N1} amide moieties are rotated by approximately 10 from the planes of their parent Cp rings. In is noteworthy that both 4-type complexes maintain the hydrogen-bonded assembly encountered in the crystal structures of 1a, its P-oxide 2a, and the bis(phosphine) complexes 3a and 3b, forming dimers through a pair of N1eH1N/O2 hydrogen bonds. Also operating are the intramolecular N2eH2N/O1 hydrogen bonds between the terminal NH moiety and the amide oxygen and supportive CeH/O1 contacts (Fig. 9; for H-bond parameters, see

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Table 4). The crystal structures have also been determined for the analogous bis-chelate complexes 5a$CHCl3 and 5b$2CH2Cl2 (Fig. 10 and Table 3). A comparison with the structures of their PdeCl precursors discussed above reveals that the replacement of the chloride ligand by the amide oxygen results in a reduced span of the Pddonor distances (cf. ca. 0.4 in 4a$3CHCl3/4b$2.5CHCl3 and 0.25 Å in 5a$CHCl3/5b$2CH2Cl2; see Table 3). Although the interligand angles remain largely unchanged between 4a/4b and 5a/5b, the coordination spheres of the Pd(II) centers in the latter cationic complexes are considerably less twisted, as shown by the angles subtended by the {Pd, P, O1} and {Pd, N3, C40} half-planes of 3.7(1) and 10.29(9) for 5a$CHCl3 and 5b$2CH2Cl2, respectively. Formation of the O,P-chelate ring expectedly leads to pronounced conformational changes at the phosphinoferrocene ligand. Compared with uncoordinated 1a and with complexes 4a$3CHCl3 and 4b$2.5CHCl3, the substituents at the ferrocene unit are much closer, adopting practically eclipsed positions (the ferrocene cyclopentadienyls are nearly in synperiplanar eclipsed conformation), and the ferrocene cyclopentadienyls are tilted more than in the PdeCl precursors (tilt angles: ca. 6e7 ). Furthermore,

the amide planes are rotated from their bonding cyclopentadienyl planes by as much as 37.5(3) and 31.1(2) due to the coordination of the C]O oxygen to the palladium center. The geometry of the palladacycles including the orientation of the benzene ring relative to the {Pd, N3, C40} plane (dihedral angles: 21.2(1) and 17.5(1) for 5a$CHCl3 and 5b$2CH2Cl2) remain minimally altered during the closure of the second chelate ring. This becomes apparent upon an inspection of the ring-puckering parameters [27], which are similar in all structurally characterized (LNC)Pd complexes with ligands 1 [28]. Even the crystal assembly of 5a$CHCl3 preserves the hydrogenbonded moiety detected in the crystal structure of the free ligand and its Pd(II) complexes (H-bond parameters are given in Table 4). In this case, however, the amide NH group (N1eH1N) forms an additional hydrogen bridge toward fluorine in the proximal hexafluoroantimonate anion (Fig. 11). The structure of 5b$2CH2Cl2 is built up from the analogous dimeric units except that the SbF 6 anion is differently positioned and does not therefore form hydrogen bridges to the NH groups [29]. The molecular structure determined for complex 5d with the Nacetyl amide ligand features several notable structural differences

Fig. 5. (a) PLATON plot of the complex molecule in the structure of 3a$2CHCl3. Displacement ellipsoids are scaled to the 30% probability level. (b) Section of the infinite hydrogenbonded chains in the structure of 3a$2CHCl3. For clarity, only the NH hydrogens are shown, and the propagation of the assembly is indicated with yellow arrows. Note: Primelabeled atoms are generated by crystallographic inversion. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

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Fig. 6. PLATON plot of the complex molecule in the structure of 3b$2CHCl3 at the 30% probability level. Prime-labeled atoms are generated by crystallographic inversion.

with respect to the “reference” structures of the complexes with ligands bearing acylurea substituents (Fig. 12 and Table 3). The Pddonor distances in the structure of 5d depart rather marginally from those of 5a$CHCl3 and 5b$2CH2Cl2, but the interligand angles differ quite significantly. An observed opening of the O1ePdeP angle and closure of the PePdeC40 angle (the other two angles around Pd(II) change much less) are probably associated with different overall conformation. The donor substituents at the ferrocene moiety in 5d are more distant than in 5a/5b, approaching a synclinal eclipsed position (cf. t angle of 61.2(2) with the ideal value 72 ), which in turn allows for smaller twisting of the amide plane (by ~18 ). In contrast, the crystal packing of 5d resembles that of the compounds discussed above as it is based on centrosymmetric dimers connected by the N1eH1N/O2 hydrogen bonds, which are supported by the soft C2eH2/O2 interactions (Fig. 12 and Table 4) [29].

3. Conclusion A series of new polar ferrocene phosphines possessing extended acylurea and acylamide pendant moieties, compounds 1a-d, was prepared via reactions of organic isocyanates or carbamoyl and acyl chlorides with 10 -(diphenylphosphino)ferrocenecarboxamide (1). In palladium(II) complexes, these compounds coordinate as simple phosphines, but can be converted to P,O-chelating donors upon the removal of the other Pd-bound ligand. Compounds possessing the CONHCONHR groups (1a and 1b) crystallize more easily than their N,N-terminally disubstituted analogue 1c and the acyl derivative 1d. The crystal structures of 1a and 2a reveal the formation of dimeric assemblies via NeH/O]C hydrogen bonds between the terminal NH groups and amide oxygens while an additional, intramolecular hydrogen bond of this type involving the acyl-NH and the urea C]O moieties is most likely responsible for the stabilization of an all-in-plane conformation, which allows for extensive conjugation. More importantly, the crystal structures determined for the entire series derived from ligand 1adthe free ligand, its phosphine oxide 2a, and all three palladium(II) complexes prepareddindicate that such a structural motif can be retained even after oxidation at the phosphine phosphorus or after coordination. 4. Experimental 4.1. General considerations

Fig. 7. PLATON plot of the complex molecule in the structure of 3d$2CHCl3 showing displacement ellipsoids at the 30% probability level. Prime-labeled atoms are generated by inversion operation.

All syntheses were performed under argon using the standard Schlenk techniques. Amide 1 [14] and di-m-chlorobis{2-[(dimethylamino-kN)methyl]phenyl-kC1}dipalladium(II) [30] were prepared according to the literature. Other chemicals were obtained from commercial sources (Sigma-Aldrich, Alfa-Aesar). Dry and deoxygenated dichloromethane and tetrahydrofuran were obtained from a PureSolv MD5 solvent purification system (Innovative Technology Inc., Amesbury, USA). Toluene was dried over sodium metal and distilled under argon. Solvents employed during chromatography and for crystallizations were used without any additional purification (reagent grade from Lachner, Czech Republic). 1 H NMR spectra were recorded at 25  C on a Varian UNITY Inova 400 spectrometer (1H, 399.95 MHz, 13C{1H}, 100.58 MHz, and 31P

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Table 2 Selected distances and angles for 3a$2CHCl3, 3b$2CHCl3, and 3d$2CHCl3 (in Å and deg).a Parameter

3a$2CHCl3

3b$2CHCl3

3d$2CHCl3

PdeCl PdeP ClePdePb FeeCgC FeeCgP :CpP,CpC

2.2920(6) 2.3316(7) 86.12(2) 1.648(1) 1.641(1) 4.7(1) 137.0(1) 1.799(2) 1.821(2) 1.826(2) 1.219(3) 1.378(3) 1.406(4) 1.231(3) 1.337(3) 123.8(2) 117.9(2) 125.2(3) 116.9(2) 13.6(3)

2.301(2)/2.265(8)c 2.3391(5) 89.10(4)/85.9(2)c 1.643(1) 1.644(1) 3.5(2) 145.1(2) 1.803(2) 1.820(2) 1.819(2) 1.227(3) 1.377(3) 1.399(3) 1.221(3) 1.340(3) 122.6(2) 119.1(2) 124.4(2) 116.5(2) 16.3(3)

2.3027(6) 2.3317(6) 85.90(2) 1.648(1) 1.648(1) 3.1(2) 153.2(2) 1.802(2) 1.814(2) 1.825(2) 1.222(3) 1.377(3) 1.380(3) 1.211(3) e 122.7(2) 118.4(2) e e 10.8(3)

t P1eC6 P1eC12 P1eC18 C11eO1 C11eN1 N1eC24 C24eO2 N2eC24 O1eC11eN1 O2eC24eN1 O2eC24eN2 N1eC24eN2 4 a b c

All parameters are defined as for the free ligands (see Table 1). The more acute of the two complementary ClePdeP angles is given. Distances for two positions of the disordered chloride ligand.

{1H}, 161.90 MHz). Chemical shifts (d/ppm) are given relative to internal tetramethylsilane (for 1H and 13C NMR) and to external 85% aqueous H3PO4 (for 31P NMR). Electrospray ionization mass spectra (ESI-MS) were recorded with a Bruker Esquire 3000 spectrometer using samples dissolved in HPLC-grade methanol. Infrared spectra were measured on a Nicolet Magna 6700 FTIR instrument in the range 400e4000 cm1. Elemental analyses were determined by the conventional combustion method using a PE 2400 Series II CHNS/O Elemental Analyzer (Perkin Elmer). The amount of clathrated solvent(s) (if any) was verified by NMR analysis. 4.2. Synthesis of N-[(ethylamino)carbonyl]-10 (diphenylphosphino)-ferrocenecarboxamide (1a) A reaction flask equipped with a stirring bar was charged with amide 1 (103.5 mg, 0.25 mmol), flushed with argon, and sealed with a septum. The solid was dissolved in THF (5 mL), and the solution was cooled in an ice bath before neat ethyl isocyanate (30 mL, 0.38 mmol) and a LiHMDS solution (0.63 mL of 1 M solution in THF, 0.63 mmol) were added with stirring. After the addition, the stirring was continued at 0  C for 30 min and then at room temperature overnight, during which time an orange precipitate separated. The reaction mixture was evaporated under vacuum, and the crude product was purified by chromatography over a silica gel column using dichloromethane-methanol (50:1) as the eluent. Evaporation of a dominant orange band provided partly solvated 1a as an orange solid. Yield of 1a$1/3CH2Cl2: 96 mg, 75%. 1 H NMR (CDCl3): d 1.23 (t, 3JHH ¼ 7.3 Hz, 3H, CH2CH3), 3.38 (dq, 3 JHH ¼ 5.6, 7.3 Hz, 3H, CH2CH3), 4.17 (vq, J0 ¼ 1.8 Hz, 2H, fc), 4.34 (vt, J0 ¼ 2.1 Hz, 2H, fc), 4.45 (vt, J0 ¼ 1.8 Hz, 2H, fc), 4.76 (vt, J0 ¼ 2.0 Hz, 2H, fc), 7.30e7.38 (m, 10H, PPh2), 8.45 (s, 1H, NH), 8.53 (t, 3 JHH ¼ 5.4 Hz, 1H, NH). 13C{1H} NMR (CDCl3): d 14.94 (s, 1C, CH2CH3), 34.76 (s, 1C, CH2CH3), 69.70 (s, 2C, CH fc), 73.25 (d, JPC ¼ 7 Hz, 2C, CH fc), 73.61 (d, JPC ¼ 85 Hz, 2C, CeP fc), 74.49 (d, JPC ¼ 13 Hz, 2C, CH fc), 78.63 (d, JPC ¼ 9 Hz, 1C, CeCO fc), 127.98 (d, 3JPC ¼ 7 Hz, 4C, CHmeta PPh2), 128.79 (s, 2C, CHpara PPh2), 133.45 (d, 2JPC ¼ 20 Hz, 4C, CHortho PPh2), 138.22 (d, 1JPC ¼ 10 Hz, 2C, Cipso PPh2), 153.79 (s, 1C, NHC(O) NHPh), 171.79 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 17.6 (s). IR (Nujol, cm1): 3321 m, 3227 m, 3110 w, 1683 s, 1668 s, 1542 s, 1492 s, 1433 m, 1313 w, 1281 s, 1240 m, 1161 w, 1111 w, 1029 m, 894 w, 832 m, 822 m, 771 m, 744 m, 696 m, 678 m, 519 w, 501 m, 449 w. ESI þ MS: m/z 507 ([1a þ Na]þ), 523 ([1a þ K]þ). Anal. calc. for C26H25FeN2O2P$1/3CH2Cl2 (512.61): C 61.70, H 5.05, N 5.47%. Found: C 61.92, H 4.83, N 5.37%. 4.3. Synthesis of N-[(phenylamino)carbonyl]-10 (diphenylphosphino)ferrocenecarboxamide (1b)

Fig. 8. PLATON plots of the complex molecules in the crystal structures of 4a$3CHCl3 (top) and 4b$2.5CHCl3 (bottom). The displacement ellipsoids correspond to the 30% probability level.

A reaction flask equipped with a stirring bar was charged with amide 1 (207 mg, 0.50 mmol), flushed with argon, and sealed with a septum. Dry THF (11 mL) was introduced, and the resulting suspension was treated with phenyl isocyanate (0.11 mL, 1 mmol). The reaction mixture was warmed to 70  C and stirred at this temperature overnight, whereupon the solid educt dissolved. Next, it was evaporated under vacuum with chromatography-grade silica. The pre-adsorbed crude product was transferred onto the top of a silica gel column, which was eluted with dichloromethane-methanol (50:1 v/v). The first band containing the product was collected and evaporated to afford 1b$1/6CH2Cl2 as an orange solid (147 mg, 54%). The subsequent band was due to unreacted amide. 1 H NMR (CDCl3): d 4.18 (vq, J0 ¼ 1.8 Hz, 2H, fc), 4.39 (vt, J0 ¼ 1.9 Hz, 2H, fc), 4.47 (vt, J0 ¼ 1.8 Hz, 2H, fc), 4.90 (vt, J0 ¼ 1.9 Hz, 2H, fc), 7.11e7.16 (m, 1H, NHPh), 7.28e7.38 (m, 12H, PPh2 and NHPh), 7.58e7.62 (m, 2H, NHPh), 8.95 (s, 1H, NH), 10.84 (s, 1H, NH). 13 1 C{ H} NMR (CDCl3): d 70.01 (s, 2C, CH fc), 73.32 (d, JPC ¼ 3 Hz, 2C,

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Table 3 Selected distances and angles for 4a$3CHCl3, 4b$2.5CHCl3, 5a$CHCl3, 5b$2CH2Cl2, and 5d (in Å and deg).a Parameter

4a$3CHCl3

4b$2.5CHCl3

5a$CHCl3

5b$2CH2Cl2

5d

X

Cl

Cl

O1

O1

O1

PdeX PdeP PdeN3 PdeC40 XePdeP XePdeN3 PePdeC40 N3ePdeC40 FeeCgC FeeCgP :CpP,CpC

2.3999(7) 2.2553(6) 2.153(2) 2.005(3) 90.13(2) 91.86(6) 98.37(6) 81.35(9) 1.649(1) 1.648(1) 1.5(1) 81.7(2) 1.814(2) 1.826(2) 1.820(2) 1.231(4) 1.376(4) 1.403(4) 1.229(4) 1.329(4) 122.2(3) 118.8(3) 123.5(3) 117.7(3) 9.4(3)

2.3989(5) 2.2472(6) 2.151(2) 2.012(2) 91.58(2) 91.81(5) 97.13(6) 81.79(8) 1.647(1) 1.647(1) 1.1(1) 82.6(2) 1.810(2) 1.819(2) 1.820(2) 1.227(3) 1.377(3) 1.403(3) 1.223(3) 1.349(3) 122.2(2) 118.8(2) 124.6(2) 116.6(2) 10.6(2)

2.152(2) 2.2574(7) 2.145(2) 1.992(2) 89.83(5) 89.65(7) 98.38(7) 82.24(9) 1.658(1) 1.652(1) 6.1(1) 5.5(2) 1.791(2) 1.826(3) 1.827(3) 1.246(3) 1.353(3) 1.412(4) 1.235(3) 1.318(4) 120.6(2) 117.0(2) 124.0(3)/121.4(8)b 118.9(2)/113.8(8)b 37.5(3)

2.177(1) 2.2459(6) 2.136(2) 1.992(2) 89.77(4) 90.46(6) 97.35(7) 83.22(8) 1.654(1) 1.649(1) 6.8(1) 9.9(2) 1.791(2) 1.820(2) 1.834(2) 1.248(3) 1.355(3) 1.409(3) 1.223(3) 1.339(3) 121.2(2) 117.4(2) 125.9(2) 116.6(2) 31.1(2)

2.167(2) 2.2724(7) 2.134(2) 1.988(2) 95.78(5) 90.95(7) 92.47(7) 81.25(8) 1.646(1) 1.650(1) 5.9(2) 61.2(2) 1.812(2) 1.817(3) 1.821(2) 1.241(3) 1.372(3) e 1.218(4) 1.394(4) 120.3(3) 117.9(3) 121.5(3) 120.6(3) 17.9(3)

t P1eC6 P1eC12 P1eC18 C11eO1 C11eN1 N1eC24 C24eO2 N2eC24 O1eC11eN1 O2eC24eN1 O2eC24eN2 N1eC24eN2 4 a b

The parameters are defined as for the free ligands (see footnote to Table 1). Angles for two positions of the disordered ethyl group.

Table 4 Hydrogen bond parameters for 4a$3CHCl3, 4b$2.5CHCl3, 5a$CHCl3, 5b$2CH2Cl2, and 5d (in Å and deg).a DH/A Complex 4a$3CHCl3 N1eH1N/O2i C5eH5/O2i N2eH2N/O1b Complex 4b$2.5CHCl3 N1eH1N/O2ii C2eH2/O2ii N2eH2N/O1b Complex 5a$CHCl3 N1eH1N/O2iii N2eH2N/F4 N2eH2N/O1b Complex 5b$2CH2Cl2 N1eH1N/O2iv N2eH2N/O1b Complex 5d N1eH1N/O2v C2eH2/O2v

D/A (Å)

Angle at H ( )

2.865(3) 3.143(4) 2.657(3)

169 144 136

2.868(3) 3.143(3) 2.668(2)

176 143 140

2.758(3) 2.911(3) 2.731(3)

166 127 129

2.806(2) 2.708(2)

157 130

2.923(3) 3.109(4)

170 154

a Legend: D ¼ donor, A ¼ acceptor. Symmetry codes: i. (1x, 1y, 1z), ii. (1x, y, 1z), iii. (1x, y, 1z), iv. (2x, 1y, 1z), v. (2x, 2y, 1z). b Intramolecular hydrogen bond.

Fig. 9. View of the dimeric, hydrogen-bonded unit in the crystal structure of 4a$3CHCl3. For clarity, only the NH hydrogens and one position of the disordered ethyl group are shown (the supporting CeH/O interactions are not shown).

CH fc), 73.57 (d, JPC ¼ 2 Hz, 2C, CH fc), 74.65 (d, JPC ¼ 14 Hz, 2C, CH fc), 78.75 (d, JPC ¼ 9 Hz, 1C, CeP fc), 120.31 (s, 1C, CH NHPh), 124.21 (s, 2C, CH NHPh), 128.30 (d, 3JPC ¼ 7 Hz, 4C, CHmeta PPh2), 128.80 (s, 2C, CHpara NHPh), 129.01 (s, 2C, CHpara PPh2), 133.46 (d, 2JPC ¼ 20 Hz,

4C, CHortho PPh2), 137.39 (s, 1C, Cipso NHPh), 138.12 (d, 1JPC ¼ 10 Hz, 2C, Cipso PPh2), 151.59 (s, 1C, NHC(O)NHPh), 172.49 (s, 1C, fcC(O)NH). A signal due to ferrocene CeCO is most likely obscured by the solvent resonance. 31P{1H} NMR (CDCl3): d 17.8 (s). IR (Nujol, cm1): 3412 w, 3231 w, 3075 w, 3124 w, 1701 s, 1670 s, 1600 s, 1560 s, 1496 s, 1447 w, 1437 w, 1311 m, 1280 s, 1227 s, 1148 m, 1082 w, 1035 m, 1025 m, 942 w, 885 w, 827 m, 766 s, 754 m, 733 m, 699 m, 634 w, 568 m, 521 w, 489 m, 481 m, 455 m, 424 w. ESI þ MS: m/z 555 ([1b þ Na]þ), 571 ([1b þ K]þ). Anal. calc. for C30H25FeN2O2P$1/6CH2Cl2 (546.49): C 66.30, H 4.67, N 5.13%. Found: C 66.34, H 4.67, N 4.92%.

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Fig. 11. Dimer-like hydrogen bonded array in the structure of 5a$CHCl3. Only the NH hydrogens are shown for clarity.

Fig. 10. PLATON plots of the complex cations in the crystal structures of 5a$CHCl3 (top) and 5b$2CH2Cl2 (bottom). The displacement ellipsoids enclose the 30% probability level. Only one orientation of the disordered terminal ethyl group is shown for 5a$CHCl3.

4.4. Synthesis of N-[(dimethylamino)carbonyl]-10 (diphenylphosphino)ferrocenecarboxamide (1c) A two-necked flask was charged with amide 1 (207 mg, 0.50 mmol) and a stirring bar. The flask was flushed with argon and sealed with a septum. The amide was dissolved in dry THF (11 mL), and the solution was cooled to 78  C with an ethanol/dry ice bath and treated successively with LiHMDS (2 mL of 1 M in toluene, 2 mmol) and neat N,N-dimethylcarbamoyl chloride (92 ml, 0.6 mmol). The resulting mixture was stirred at 78  C for 1 h and

then at room temperature for another 4 h, where upon the color of the reaction mixture changed from orange-yellow to orange. The reaction mixture was then transferred to a separatory funnel and washed successively with saturated aqueous Na2CO3 and brine. The organic layer was dried over anhydrous magnesium sulfate and evaporated. The crude product was purified by chromatography over a silica gel column using dichloromethane-methanol (50:1 v/ v) as the eluent. Following evaporation, 1c$3/4CH2Cl2 was isolated as an orange solid (180 mg, 66%). Note: the compound is slowly oxidized to its corresponding phosphine oxide 2c and should be purified before use. Minor amounts of 2c can already be obtained during the synthesis if the polarity of the mobile phase is increased (e.g., to dichloromethane-methanol 20:1). 1 H NMR (CDCl3): d 3.02 (s, 6H, N(CH3)2), 4.17 (vq, J0 ¼ 1.8 Hz, 2H, fc), 4.29 (vt, J0 ¼ 1.9 Hz, 2H, fc), 4.46 (vt, J0 ¼ 1.8 Hz, 2H, fc), 4.69 (vt, J0 ¼ 1.9 Hz, 2H, fc), 7.30e7.38 (m, 10H, PPh2), 7.91 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 37.8 (br s, 6C, N(CH3)2), 69.94 (s, 2C, CH fc), 72.82 (s, 2C, CH fc), 73.00 (d, JPC ¼ 4 Hz, 2C, CH fc), 74.34 (d, JPC ¼ 14 Hz, 2C, CH fc), 74.79 (s, 1C, CeCO fc), 78.06 (d, JPC ¼ 9 Hz, 1C, CeP fc), 128.28 (d, 3JPC ¼ 7 Hz, 4C, CHmeta PPh2), 128.76 (s, 2C, CHpara PPh2), 133.45 (d, 2JPC ¼ 20 Hz, 4C, CHortho PPh2), 138.28 (d, 1JPC ¼ 10 Hz, 2C, Cipso PPh2), 154.36 (s, 1C, NHC(O)N), 168.70 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 17.3 (s). IR (Nujol, cm1): 3207 m, 1667 s, 1584 w, 1398 m, 1346 w, 1309 w, 1274 s, 1223 w, 1201 s, 1159 m, 1143 w, 1100 w, 1066 m, 1042 w, 1026 m, 1001 w, 943 m, 909 w, 883 w, 862 m, 848 w, 837 m, 826 w, 789 m, 767 m, 743 s, 707 m, 697 s, 637 m, 598 w, 569 m, 524 m, 511 w, 497 s, 486 w, 464 w, 451 m, 424 m, 412 w. ESIeMS: m/z 483 ([1c  H]e). Anal. calc. for C26H25FeN2O2P$3/ 4CH2Cl2 (547.99): C 58.63, H 4.87, N 5.11%. Found: C 58.79, H 4.86, N 5.02%. 4.5. Synthesis of N-acetyl-10 -(diphenylphosphino)ferrocenecarboxamide (1d) Compound 1d was prepared similarly to 1c starting from amide 1 (207 mg, 0.50 mmol) in THF (8 mL), LiHMDS (2 mL of 1 M in toluene, 2 mmol), and freshly distilled acetyl chloride (55 ml,

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Found: C 65.49, H 4.81, N 2.91%. 4.6. Preparation of phosphine oxides 2

Fig. 12. PLATON plot for compound 5d (30% probability ellipsoids; top) and the hydrogen-bonded dimers in the structure of this complex (bottom).

0.77 mmol). The reaction mixture was stirred at 78  C for 1 h and at room temperature overnight and then washed with saturated aqueous NaHCO3 and brine. Chromatography as described above afforded 1d$1/20CH2Cl2 as an orange solid (101 mg, 44%). Note: 1d elutes as a second orange band; unreacted 1 is removed for the column first. 1 H NMR (CDCl3): d 2.53 (s, 3H, CH3), 4.16 (vq, J0 ¼ 1.8 Hz, 2H, fc), 4.38 (vt, J0 ¼ 1.9 Hz, 2H, fc), 4.45 (vt, J0 ¼ 1.8 Hz, 2H, fc), 4.64 (vt, J0 ¼ 1.9 Hz, 2H, fc), 7.31e7.39 (m, 10H, PPh2), 8.22 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 25.45 (s, 1C, CH3), 69.93 (s, 2C, CH fc), 73.03 (d, JPC ¼ 4 Hz, 2C, CH fc), 73.40 (d, JPC ¼ 1 Hz, 2C, CH fc), 74.10 (s, 1C, CeCO fc), 74.53 (d, JPC ¼ 13 Hz, 2C, CH fc), 78.79 (d, JPC ¼ 9 Hz, 1C, CeP fc), 128.35 (d, 3JPC ¼ 7 Hz, 4C, CHmeta PPh2), 129.39 (s, 2C, CHpara PPh2), 133.44 (d, 2JPC ¼ 20 Hz, 4C, CHortho PPh2), 138.01 (d, 1 JPC ¼ 10 Hz, 2C, Cipso PPh2), 169.15 (s, 1C, NHC(O)CH3), 172.59 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 17.7 (s). IR (Nujol, cm1): 3250 br m, 1683 s, 1586 w, 1538 w, 1408 w, 1297 s, 1272 s, 1186 w, 1161 m, 1125 m, 1094 w, 1070 w, 1063 w, 1051 w, 1042 w, 1019 s, 998 w, 897 w, 830 s, 759 s, 750 s, 739 s, 699 s, 935 w, 572 m, 528 w, 515 w, 490 s, 467 m, 452 m, 429 m. ESIeMS: m/z 454 ([1d  H]e). Anal. calc. for C25H22FeNO2P$1/20CH2Cl2 (459.50): C 65.47, H 4.85, N 3.05%.

Phosphine oxides 2 were all prepared according to the following general procedure unless specified below. Thus, the respective compound 1 (50 mmol) was dissolved in 3 mL of reagent-grade acetone in a reaction flask equipped with a stirring bar. The reaction vessel was flushed with argon and sealed with a septum. Then, 30% aqueous hydrogen peroxide (57 mL, 0.55 mmol) was added, and the resulting mixture was stirred at room temperature for 30 min. An excess of hydrogen peroxide was destroyed by the addition of saturated aqueous sodium thiosulfate and stirring for another 15 min. The acetone was evaporated under vacuum and the aqueous residue was extracted with dichloromethane. The organic washings were combined, washed with water and brine, dried over magnesium sulfate, and finally evaporated under vacuum. The crude product was isolated by column chromatography over silica gel using dichloromethane-methanol 20:1 (v/v) as the eluent and subsequent evaporation under vacuum. The yields and characterization for the phosphine oxides are as follows. Analytical data for 2a$1/10CH2Cl2: orange solid (21 mg, 84%). 1H NMR (CDCl3): d 1.20 (t, 3JHH ¼ 7.3 Hz, 3H, CH2CH3), 3.37 (dq, 3 JHH ¼ 5.5, 7.2 Hz, 2H, CH2CH3), 4.31 (vq, J0 ¼ 2.0 Hz, 4H, fc), 4.56 (vq, J0 ¼ 2.0 Hz, 2H, fc), 5.05 (vt, J0 ¼ 2.0 Hz, 2H, fc), 7.43e7.49 (m, 4H, PPh2), 7.50e7.56 (m, 2H, PPh2), 7.71e7.78 (m, 4H, PPh2), 8.38 (t, 3 JHH ¼ 5.1 Hz, 1H, NH), 10.35 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 15.17 (s, 1C, CH2CH3), 34.77 (s, 1C, CH2CH3), 71.14 (s, 2C, CH fc), 72.33 (s, 2C, CH fc), 73.16 (d, JPC ¼ 10 Hz, 2C, CH fc), 75.12 (d, JPC ¼ 13 Hz, 2C, CH fc), 75.27 (d, 1JPC ¼ 112 Hz, 1C, CeP fc), 76.50 (s, 1C, CeCO fc), 128.61 (d, 3JPC ¼ 12 Hz, 4C, CHmeta PPh2), 131.72 (d, 2 JPC ¼ 10 Hz, 4C, CHortho PPh2), 132.08 (d, 4JPC ¼ 2 Hz, 2C, CHpara PPh2), 133.05 (d, 1JPC ¼ 108 Hz, 2C, Cipso PPh2), 153.97 (s, 1C, NHC(O) NH), 172.05 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 29.3 (s). IR (Nujol, cm1): 3463 br m, 3300 br w, 3100 br w, 1685 s, 1655 s, 1560 m, 1542 s, 1309 w, 1278 m, 1233 w, 1201 m, 1164 s, 1118 m, 1071 w, 1028 m, 998 w, 941 w, 829 m, 772 m, 752 m, 723 s, 701 s, 636 w, 568 s, 531 s, 504 s. ESI þ MS: m/z 523 ([2a þ Na]þ). C26H25Fe N2O3P$1/10CH2Cl2 (508.793): C 61.61, H 4.99, N 5.51%. Found: C 61.73, H 5.02, N 5.14%. Analytical data for 2b$1/10CH2Cl2: orange solid (25 mg, 90%). 1H NMR (CDCl3): d 4.32 (s, 4H, fc), 4.60 (s, 2H, fc), 5.14 (s, 2H, fc), 7.04e7.09 (m, 1H, NHPh), 7.27e7.33 (m, 3H, NHPh), 7.43e7.60 (m, 7H, PPh2 and NHPh), 7.72e7.80 (m, 4H, PPh2), 10.64 (s, 1H, NH), 10.96 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 71.17 (s, 2C, CH fc), 72.22 (s, 2C, CH fc), 72.98 (d, JPC ¼ 10 Hz, 2C, CH fc), 75.05 (d, JPC ¼ 112 Hz, 1C, CeP fc), 75.12 (d, JPC ¼ 13 Hz, 2C, CH fc), 75.18 (s, 1C, CeCO fc), 119.97 (s, 2C, CH NHPh), 123.57 (s, 2C, CH NHPh), 128.47 (d, 3 JPC ¼ 12 Hz, 4C, CHmeta PPh2), 128.86 (s, 2C, CHpara PPh2), 131.53 (d, 2 JPC ¼ 10 Hz, 4C, CHortho PPh2), 131.99 (s, 2C, CH NHPh), 132.60 (d, 1 JPC ¼ 108 Hz, Cipso PPh2), 137.97 (s, 1C, Cipso NHPh), 151.24 (s, 1C, NHC(O)NHPh), 172.40 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 29.8 (s). IR (Nujol, cm1): 3099 br m, 1720 s, 1701 m, 1657 s, 1590 s, 1541 s, 1497 s, 1467 s, 1446 s, 1438 s, 1120 m, 1350 m, 1310 m, 1285 s, 1256 w, 1226 m, 1195 s, 1172 s, 1148 s, 1122 s, 1106 w, 1071 m, 1059 w, 1044 w, 1032 m, 998 w, 941 m, 902 w, 888 w, 872 w, 854 w, 829 m, 821 m, 771 s, 757 s, 723 s, 703 s, 637 m, 618 w, 596 w, 567 s, 532 s, 506 s, 479 s, 464 m, 456 m, 441 w, 428 w. ESI þ MS: m/z 549 ([M þ H]þ), 571 ([2b þ Na]þ). Anal. calc. for C30H25FeN2O3P$1/ 10CH2Cl2 (556.83): C 64.92, H 4.56, N 5.03%. Found: C 65.05, H 4.48, N 4.82%. Compound 2c was isolated as an orange solid during the synthesis of phosphine 1c (yield of 2c: 52 mg or 19%) and was not therefore synthesized in a separate experiment. 1H NMR (CDCl3): d 3.04 (s, 6H, N(CH3)2), 4.21 (vt, J0 ¼ 2.0 Hz, 2H, fc), 4.34 (vq,

, et al., Journal of Organometallic Chemistry (2016), http://dx.doi.org/10.1016/ Please cite this article in press as: H. Charvatova j.jorganchem.2016.02.036

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tova  et al. / Journal of Organometallic Chemistry xxx (2016) 1e15 H. Charva

J0 ¼ 1.7 Hz, 2H, fc), 4.58 (vq, J0 ¼ 1.8 Hz, 2H, fc), 5.12 (vt, J0 ¼ 2.0 Hz, 2H, fc), 7.44e7.51 (m, 4H, PPh2), 7.52e7.58 (m, 2H, PPh2), 7.68e7.75 (m, 4H, PPh2), 10.5 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 37.2 (br s, 6C, N(CH3)2), 71.28 (s, 2C, CH fc), 71.36 (s, 2C, CH fc), 72.82 (d, JPC ¼ 11 Hz, 2C, CH fc), 74.26 (d, JPC ¼ 113 Hz, 1C, CeP fc), 74.98 (d, JPC ¼ 13 Hz, 2C, CH fc), 77.44 (s, 1C, CeCO fc), 128.48 (d, 3JPC ¼ 13 Hz, 4C, CHmeta PPh2), 131.43 (d, 2JPC ¼ 10 Hz, 4C, CHortho PPh2), 131.99 (d, 4 JPC ¼ 2 Hz, 2C, CHpara PPh2), 132.62 (d, 1JPC ¼ 108 Hz, 2C, Cipso PPh2), 154.50 (s, 1C, NHC(O)N), 169.31 (s, 1C, fcC(O)NH). 31P{1H} NMR (CDCl3): d 30.8 (s). IR (Nujol, cm1): 3200 m, 3094 m, 3079 m, 1712 s, 1657 m, 1589 w, 1436 m, 1341 w, 1308 w, 1261 m, 1212 w, 1201 m, 1159 s, 1120 m, 1099 w, 1068 m, 1046 w, 1033 m, 996 w, 944 w, 892 w, 861 m, 823 m, 785 m, 749 m, 724 s, 705 s, 695 m, 644 w, 605 w, 572 s, 538 w, 531 m, 509 s, 496 m, 483 m, 442 w, 418 w. ESI þ MS: m/z 523 ([2c þ Na]þ). Anal. calc. for C26H25FeN2O3P$1/ 10CH2Cl2 (508.79): C 61.61, H 4.99, N 5.51%. Found: C 61.35, H 5.06, N 5.19%. Analytical data for 2d$1/3CH2Cl2: orange solid (23 mg, 92%). 1H NMR (CDCl3): d 2.42 (s, 3H, CH3), 4.25 (vq, J0 ¼ 1.7 Hz, 2H, fc), 4.29 (vt, J0 ¼ 2.0 Hz, 2H, fc), 4.58 (vq, J0 ¼ 2.1 Hz, 2H, fc), 5.13 (vt, J0 ¼ 2.0 Hz, 2H, fc), 7.46e7.51 (m, 4H, PPh2), 7.53e7.59 (m, 2H, PPh2), 7.69e7.76 (m, 4H, PPh2), 11.37 (s, 1H, NH). 13C{1H} NMR (CDCl3): d 25.42 (s, 1C, CH3), 71.33 (s, 2C, CH fc), 72.01 (s, 2C, CH fc), 72.87 (d, JPC ¼ 11 Hz, 2C, CH fc), 74.73 (d, JPC ¼ 111 Hz, 1C, CeP fc), 75.08 (d, JPC ¼ 13 Hz, 2C, CH fc), 128.53 (d, 3JPC ¼ 12 Hz, 4C, CHmeta PPh2), 131.47 (d, 2JPC ¼ 10 Hz, 4C, CHortho PPh2), 132.10 (d, 4JPC ¼ 2 Hz, 2C, CHpara PPh2), 132.43 (d, 1JPC ¼ 108 Hz, 2C, Cipso PPh2), 169.65 (s, 1C, NHC(O)CH3), 172.02 (s, 1C, fcC(O)NH). The resonance due to ferrocene CeCO is most likely overlapped by the signal of the solvent. 31P {1H} NMR (CDCl3): d 30.9 (s). IR (Nujol, cm1): 3200 br w, 1743 s, 1713 s, 1683 s, 1590 w, 1309 w, 1263 s, 1216 m, 1186 m, 1160 s, 1118 s, 1070 w, 1027 m, 998 w, 783 m, 822 m, 752 m, 723 s, 702 s, 638 w, 569 s, 535 s, 502 s, 449 m, 411 m. ESI þ MS: m/z 413 ([2deNHCOCH3]þ), 472 ([2d þ H]þ), 494 ([2d þ Na]þ). Anal. calc. for C25H22FeNO3P$1/3CH2Cl2 (499.57): C 60.90, H 4.57, N 2.80%. Found: C 60.88, H 4.55, N 2.44%. 4.7. Synthesis of complex 3a Because of very poor solubility for crystalline 3a, this compound was prepared by a reactive diffusion approach as follows. A solution of ligand 1a (12 mg, 25 mmol) in chloroform (2 mL) was carefully layered with a dichloromethane solution of [PdCl2(cod)] (3.6 mg, 12.5 mmol). The starting materials reacted slowly upon liquid-phase diffusion, and once a red solution was formed, diethyl ether was added as the top layer to induce crystallization. Red crystals, which separated over several days, were isolated by suction, washed with diethyl ether, and dried under vacuum. Yield: orange-red crystals (103 mg, 79%). IR (Nujol, cm1): 3310 w, 3227 w, 3109 w, 1681 s, 1541 m, 1482 m, 1437 w, 1277 s, 1235 m, 1165 m, 1100 w, 1035 w, 829 m, 773 m, 743 m, 694 m, 626 w, 532 w, 516 m, 500 m, 475 w. ESI þ MS: m/z 507 ([1a þ Na]þ), 649 ([PdCl(1a) þ Na  H]þ). ESIeMS: m/z 625 ([PdCl(1a)  2H]e). Anal. calc. for C52H50Cl2Fe2N4O4P2Pd (1145.90): C 54.50, H 4.40, N 4.89%. Found: C 54.42, H 4.23, N 4.77%. 4.8. Synthesis of palladium(II) complexes 3b-d Complexes 3b-d were prepared and isolated in the same manner as follows. [PdCl2(cod)] (7.1 mg, 25 mmol) and the respective ligand 1 (50 mmol) were dissolved in dichloromethane (3 mL), and the resulting solution was stirred for 30 min and then precipitated with hexane. The separated solid was isolated by centrifugation, washed with hexane, and dried under vacuum. The majority of complexes 3 are poorly soluble in all common deuterated

solvents, which precluded analysis of these compounds by NMR spectroscopy. Analytical data for 3b$1/2CH2Cl2: orange solid (27 mg, 83%). 1H NMR (CDCl3): d 4.54 (s, 4H, fc), 4.64 (vt, J0 ¼ 1.8 Hz, 4H, fc), 4.83 (vt, J0 ¼ 1.9 Hz, 4H, fc), 5.35 (vt, J0 ¼ 2.0 Hz, 4H, fc), 7.07e7.13 (m, 2H, NHPh), 7.33e7.38 (m, 4H, NHPh), 7.47e7.62 (m, 24H, PPh2 and NHPh), 10.56 (s, 2H, NH), 10.89 (s, 2H, NH). 31P{1H} NMR (CDCl3): d 16.2 (s). IR (Nujol, cm1): 3223 br m, 3105 br m, 1694 s, 1666 s, 1595 s, 1553 s, 1485 s, 1447 s, 1436 w, 1339 w, 1310 m, 1278 s, 1228 s, 1185 w, 1166 m, 1147 s, 1100 m, 1061 w, 1036 m, 1027 m, 1000 w, 942 w, 913 m, 882 w, 839 m, 817 w, 772 s, 750 s, 730 s, 695 s, 649 w, 627 w, 617 w, 565 m, 540 m, 507 s, 494 w, 470 m, 435 m. ESI þ MS: m/z 695 ([PdCl(1b) þ Na  H]þ). Anal. calc. for C60H50O4N4Fe2P2PdCl2$1/2CH2Cl2 (1284.44): C 56.57, H 4.00, N 4.36%. Found: C 56.75, H 4.01, N 4.19%. Analytical data for 3c$1/5CH2Cl2$1/5C6H14: orange solid (30 mg, quant.). 1H NMR (CDCl3): d 2.91 (s, 12H, N(CH3)2), 4.54 (s, 4H, fc), 4.58 (vt, J0 ¼ 1.7 Hz, 4H, fc), 4.74 (vt, J0 ¼ 1.9 Hz, 4H, fc), 5.11 (vt, J0 ¼ 1.9 Hz, 4H, fc), 7.45e7.60 (m, 20H, PPh2), 9.54 (s, 2H, NH). 31P {1H} NMR (CDCl3): d 16.5 (s). IR (Nujol, cm1): 3233 br w, 1655 s, 1436 w, 1391 m, 1271 s, 1196 m, 1165 m, 1099 m, 1060 w, 1031 m, 1000 w, 943 w, 836 m, 787 w, 747 s, 693 s, 625 w, 501 s. ESI þ MS: m/z 589 ([M  2Cl  1c  H]þ), 1028 ([M  2HCl  NMe2]þ). Anal. calc. for C52H50Cl2Fe2N4O4P2Pd$1/5CH2Cl2$1/5C6H12 (1196.55): C 54.36, H 4.51, N 4.75%. Found: C 54.61, H 4.77, N 4.40%. Analytical data for 3d$8/3CH2Cl2: orange solid (27 mg, quant.). The product precipitates during the stirring of the dichloromethane solution of the educts. 1H NMR (DMSO): d 2.36 (s, 6H, CH3), 4.52 (vt, J0 ¼ 1.8 Hz, 4H, fc), 4.60 (vt, J0 ¼ 1.8 Hz, 4H, fc), 4.78 (vt, J0 ¼ 1.9 Hz, 4H, fc), 5.23 (vt, J0 ¼ 2.0 Hz, 4H, fc), 7.46e7.60 (m, 20H, PPh2), 10.44 (s, 2H, NH). 31P{1H} NMR (DMSO): d 16.4 (s). IR (Nujol, cm1): 3232 br w, 3110 w, 1765 w, 1707 s, 1690 s, 1552 w, 1483 m, 1436 w, 1296 s, 1267 s, 1196 w, 1165 m, 1127 m, 1096 w, 1057 w, 1030 m, 999 w, 912 m, 844 m, 824 m, 766 w, 745 m, 729 s, 710 w, 695 s, 647 w, 626 w, 571 m, 542 m, 519 m, 502 m 471 m, 450 m. ESI MS: 478 [1d þ Na]þ, 618 [PdCl2(1d  CH3)]þ, 1015 [M  HCl  Cl]þ. Anal. calc. for C50H44Cl2Fe2N2O4P2Pd$8/3CH2Cl2 (1314.28): C 48.13, H 3.78, N 2.13%. Found: C 48.08, H 3.55, N 2.07%. 4.9. Synthesis of complexes 4 The appropriate ligand 1 (50 mmol) and di-m-chlorobis{2[(dimethylamino-kN)methyl]phenyl-kC1]dipalladium(II) (13.8 mg, 25 mmol) were dissolved in dichloromethane (3 mL) under argon. The resulting solution was stirred for 1 h and then evaporated to dryness. Analytical data for 4a$CHCl3: orange crystals from chloroformhexane (37 mg, 85%). 1H NMR (CDCl3): d 1.21 (t, 3JHH ¼ 7.3 Hz, 3H, CH2CH3), 2.87 (d, 4JPH ¼ 2.7 Hz, 6H, N(CH3)2), 3.36 (dq, 3JHH ¼ 5.5, 7.3 Hz, 2H, CH2CH3), 4.14 (d, 4JPH ¼ 2.2 Hz, 1H, NCH2C6H4), 4.41e4.45 (m, 2H, fc), 4.53 (vq, J0 ¼ 1.8 Hz, 2H, fc), 4.96 (vt, J0 ¼ 2.1 Hz, 2H, fc), 5.02 (vt, J0 ¼ 2.0 Hz, 2H, fc), 6.23 (ddd, J ¼ 1.2, 6.6, 7.7 Hz, 1H, C6H4), 6.38 (td, J ¼ 1.6, 7.8 Hz, 1H, C6H4), 6.83 (td, J ¼ 1.1, 7.3 Hz, 1H, C6H4), 7.02 (td, J ¼ 1.6, 7.4 Hz, 1H, C6H4), 7.31e7.37 (m, 4H, PPh2), 7.39e7.45 (m, 2H, PPh2), 7.52e7.59 (m, 4H, PPh2), 8.08 (s, 1H, NH), 8.45 (t, JHH ¼ 545 Hz, 1H, NH). 31P{1H} NMR (CDCl3): d 32.3 (s). ESI þ MS: m/ z 679 ([4a  HCl  NHEt]þ), 724 ([4a  Cl]þ). Anal. calc. for C35H37ClFeN3O2PPd$CHCl3 (879.71): C 49.15, H 4.35, N 4.78%. Found: C 49.08, H 4.29, N 4.64%. Analytical data for 4b: orange solid (40 mg, quant.). 1H NMR (CDCl3): d 2.87 (d, 4JPH ¼ 2.7 Hz, 6H, N(CH3)2), 4.15 (d, 4JPH ¼ 2.2 Hz, 1H, NCH2C6H4), 4.46e4.48 (m, 2H, fc), 4.54 (vq, J0 ¼ 1.9 Hz, 2H, fc), 5.06 (vt, J0 ¼ 1.9 Hz, 2H, fc), 5.13 (vt, J0 ¼ 1.9 Hz, 2H, fc), 6.24 (ddd, J ¼ 1.1, 6.4, 7.7 Hz, 1H, C6H4), 6.38 (td, J ¼ 1.3, 7.6 Hz, 1H, C6H4), 6.84 (td, J ¼ 1.1, 7.4 Hz, 1H, C6H4), 7.03 (td, J ¼ 1.5, 7.4 Hz, 1H, C6H4),

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7.07e7.12 (m, 1H, NHPh), 7.27e7.35 (m, 6H, PPh2 and NHPh), 7.38e7.43 (m, 2H, PPh2 and NHPh), 7.52e7.59 (m, 6H, PPh2), 8.83 (s, 1H, NH), 10.78 (s, 1H, NH). 31P{1H} NMR (CDCl3): d 32.3 (s). IR (Nujol, cm1): 3320 br m, 1698 s, 1662 m, 1596 s, 1557 s, 1486 m, 1447 w, 1311 w, 1279 s, 1223 s, 1178 w, 1164 w, 1144 m, 1099 m, 1029 m, 998 w, 941 w, 882 w, 844 m, 762 s, 744 s, 696 s, 629 w, 601 w, 567 m, 542 m, 524 w, 509 s, 474 m, 434 m. ESI þ MS: m/z 772 ([4b  Cl]þ). Anal. calc. for C39H37ClFeN3O2PPd (808.39): C 57.94, H 4.61, N 5.20%. Found: C 57.85, H 4.58, N 4.84%. Analytical data for 4c$1/2CH2Cl2: orange solid (40 mg, quant.). 1 H NMR (CDCl3): d 2.86 (d, 4JPH ¼ 2.7 Hz, 6H, PdN(CH3)2), 3.01 (s, 6H, C(O)N(CH3)2), 4.13 (d, 4JPH ¼ 2.3 Hz, 2H, NCH2C6H4), 4.48 (br s, 2H, fc), 4.52 (vq, J0 ¼ 1.7 Hz, 2H, fc), 4.89 (vt, J0 ¼ 1.7 Hz, 2H, fc), 4.99 (vt, J0 ¼ 1.7 Hz, 2H, fc), 6.23 (ddd, J ¼ 1.2, 6.7, 7.7 Hz, 1H, C6H4), 6.37 (td, J ¼ 1.5, 7.6 Hz, 1H, C6H4), 6.82 (td, J ¼ 1.0, 7.2 Hz, 1H, C6H4), 7.00 (td, J ¼ 1.5, 7.3 Hz, 1H, C6H4), 7.30e7.36 (m, 4H, PPh2), 7.38e7.44 (m, 4H, PPh2), 7.52e7.60 (m, 4H, PPh2), 7.89 (s, 1H, NH). 31P{1H} NMR (CDCl3): d 32.4 (s). IR (Nujol, cm1): 3200 br w, 1657 s, 1579 w, 1437 w, 1305 w, 1270 s, 1195 m, 1164 s, 1099 m, 1061 w, 1029 m, 997 w, 972 w, 941 w, 845 m, 796 w, 743 s, 696 s, 629 w, 543 w, 522 m, 503 m, 476 m, 438 w. ESI þ MS: m/z 679 ([4c  HCl  NMe2]þ), 724 ([4c  Cl]þ). Anal. calc. for C35H37ClFeN3O2PPd$1/2CH2Cl2 (802.81): C 53.11, H 4.77, N 5.24%. Found: C 53.33, H 4.84, N 5.08%. Analytical data for 4d$2/5CH2Cl2: orange solid (38 mg, 99%). 1H NMR (CDCl3): d 2.52 (s, 3H, CH3), 2.90 (d, 4JPH ¼ 2.7 Hz, 6H, N(CH3)2), 4.16 (d, 4JPH ¼ 2.2 Hz, 1H, NCH2C6H4), 4.45e4.47 (m, 2H, fc), 4.54 (vq, J0 ¼ 1.9 Hz, 2H, fc), 4.97e5.00 (m, 4H, fc), 6.22e6.27 (m, 1H, C6H4), 6.36e6.42 (m, 1H, C6H4), 6.82e6.87 (m, 1H, C6H4), 7.02e7.05 (m, 1H, C6H4), 7.33e7.39 (m, 4H, PPh2), 7.42e7.47 (m, 2H, PPh2), 7.55e7.61 (m, 4H, PPh2), 8.43 (s, 1H, NH). 31P{1H} NMR (CDCl3): d 32.3 (s). IR (Nujol, cm1): 3250 br w, 1744 w, 1709 m, 1687 s, 1579 w, 1263 s, 1164 m, 1120 m, 1099 m, 1019 m, 994 w, 972 w, 844 m, 823 w, 742 s, 695 s, 629 w, 566 w, 543 m, 520 m, 504 m, 477 m. ESI þ MS: m/z 695 ([4d  Cl]þ). Anal. calc. for C34H34ClFeN2O2PPd$2/5CH2Cl2 (765.27): C 53.99, H 4.58, N 3.66%. Found: C 53.87, H 4.65, N 3.36%. 4.10. Preparation of complexes 5 The respective ligand 1 (50 mmol) and di-m-chlorobis{2[(dimethylamino-kN)methyl]phenyl-kC1]dipalladium(II) (13.8 mg, 25 mmol) were dissolved in dichloromethane (3 mL) under argon, and the resulting solution was stirred for 1 h. Solid Ag[SbF6] (17.2 mg, 50 mmol) was added, causing immediate separation of a white precipitate (AgCl). After stirring for another 1 h, the mixture was filtered through a PTFE syringe filter (0.45 mm pore size) and evaporated under vacuum to afford crude 5. The complex was dissolved in a suitable solvent and crystallized by liquid-phase diffusion of diethyl ether or diethyl ether/hexane. The separated crystalline product was filtered off, washed with diethyl ether or hexane, and dried under vacuum. Analytical data for 5a. Crystallization from chloroform-diethyl ether and isolation as described above afforded 5a$4/3CHCl3 as an orange crystalline solid (29 mg, 52%). 1H NMR (DMSO): d 1.12 (t, 3 JHH ¼ 7.2 Hz, 3H, CH2CH3), 2.68 (br s, 6H, N(CH3)2), 3.23 (qi, JHH ¼ 6.6 Hz, 2H, CH2CH3), 3.90 (s, 2H, fc), 4.16 (s, 1H, NCH2C6H4), 4.47 (s, 2H, fc), 4.52 (s, 2H, fc), 5.14 (s, 2H, fc), 6.30 (t, J ¼ 6.5 Hz, 1H, C6H4), 6.52 (t, J ¼ 7.7 Hz, 1H, C6H4), 6.94 (t, J ¼ 6.8 Hz, 1H, C6H4), 7.11 (d, J ¼ 7.1 Hz, 1H, C6H4), 7.58e7.72 (m, 10H, PPh2), 8.55 (t, JHH ¼ 5.6 Hz, 1H, NH), 10.12 (s, 1H, NH). 31P{1H} NMR (DMSO): d 30.9 (s). IR (Nujol, cm1): 3393 m, 3100 br w, 1686 s, 1610 s, 1581 m, 1509 s, 1407 w, 1365 w, 1303 s, 1246 s, 1203 w, 1191 w, 1170 m, 1094 m, 1068 w, 1037 m, 1025 m, 996 m, 979 w, 945 m, 908 s, 790 w, 767 m, 746 s, 732 s, 699 s, 656 s, 604 m, 543 w, 528 s, 504 s, 482 s, 435 m. ESI þ MS: m/z 724 ([5a  SbF6]þ). Anal. calc. for

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C35H37F6FeN3O2PPdSb$4/3CHCl3 (1119.80): C 38.97, H 3.45, N 3.75%. Found: C 39.09, H 3.43, N 3.57%. Analytical data for 5b. Crystallization from dichloromethanediethyl ether afforded an orange crystalline solid (44 mg, 84%). 1H NMR (dmso-d6): d 2.69 (d, 4JPH ¼ 2.6 Hz, 6H, N(CH3)2), 3.95 (vq, J0 ¼ 2.0 Hz, 2H, fc), 4.18 (d, 4JPH ¼ 1.6 Hz, 1H, NCH2C6H4), 4.55 (vt, J0 ¼ 2.0 Hz, 2H, fc), 4.59e4.61 (m, 2H, fc), 5.21 (vt, J0 ¼ 2.0 Hz, 2H, fc), 6.30 (ddd, J ¼ 1.0, 6.2, 7.5 Hz, 1H, C6H4), 6.52 (td, J ¼ 1.5, 7.6 Hz, 1H, C6H4), 6.92 (td, J ¼ 1.0, 7.3 Hz, 1H, C6H4), 7.06e7.14 (m, 1H, C6H4 and NHPh), 7.34e7.40 (m, 2H, NHPh), 7.55e7.60 (m, 2H, NHPh), 7.60e7.72 (m, 10H, PPh2), 10.51 (s, 1H, NH), 10.82 (s, 1H, NH). 31P{1H} NMR (dmso-d6): d 30.8 (s). IR (Nujol, cm1): 3316 m, 3237 w, 3077 m, 1710 s, 1594 s, 1554 s, 1506 s, 1450 m, 1363 w, 1329 w, 1298 s, 1230 s, 1167 m, 1098 m, 1038 w, 1026 w, 988 m, 942 w, 880 w, 838 m, 743 s, 694 s, 658 s, 562 w, 528 m, 507 m, 488 m, 450 w. ESI þ MS: m/z 772 ([5b  SbF6]þ). Anal. calc. for C39H37F6FeN3O2PPdSb (1008.69): C 46.44, H 3.70, N 4.17%. Found: C 46.04, H 3.65, N 4.17%. Analytical data for 5c$3/2CH2Cl2. The “crude” product proved to be essentially pure and was therefore not crystallized: orange solid (54 mg, quant.). 1H NMR (CDCl3): d 2.78e2.95 (m, 12H, 2 N(CH3)2), 4.14 (d, 4JPH ¼ 2.3 Hz, 1H, NCH2C6H4), 4.35 (vq, J0 ¼ 2.0 Hz, 2H, fc), 4.66 (d vt, J0 ¼ 0.7, 1.8 Hz, 2H, fc), 4.70 (vt, J0 ¼ 2.0 Hz, 2H, fc), 5.46 (vt, J0 ¼ 2.0 Hz, 2H, fc), 6.23 (ddd, J ¼ 1.1, 6.5, 7.4 Hz, 1H, C6H4), 6.39 (td, J ¼ 1.7, 7.9 Hz, 1H, C6H4), 6.87 (td, J ¼ 0.8, 7.3 Hz, 1H, C6H4), 7.00 (dd, J ¼ 1.7, 7.5 Hz, 1H, C6H4), 7.37e7.48 (m, 6H, PPh2), 7.75e7.83 (m, 4H, PPh2), 8.27 (s, 1H, NH). 31P{1H} NMR (CDCl3): d 29.7 (s). IR (Nujol, cm1): 3460 w, 1697 s, 1641 s, 1582 m, 1292 m, 1262 m, 1182 m, 1167 m, 1098 m, 1064 w, 1026 m, 998 m, 912 m, 845 m, 739 s, 698 s, 660 s, 538 m, 527 m, 481 m, 437 w. ESI þ MS: m/z 724 ([5c  SbF6]þ). Anal. calc. for C35H37F6FeN3O2PPdSb$3/2CH2Cl2 (1088.04): C 40.29, H 3.71, N 3.86%. Found: C 40.66, H 3.76, N 3.67%. Analytical data 5d. The compound was crystallized from dichloromethane-diethyl ether/hexane as an orange-brown crystalline solid (34 mg, 73%). 1H NMR (dmso-d6): d 2.33 (s, 3H, CH3), 2.68 (d, 4JPH ¼ 2.7 Hz, 6H, NMe2), 3.94 (vq, J0 ¼ 2.0 Hz, 2H, fc) 4.17 (d, 4 JPH ¼ 1.8 Hz, 2H, NCH2C6H4), 4.49 (vt, J0 ¼ 2.0 Hz, 2H, fc), 4.56 (dt, J0 ¼ 1.0, 2.0 Hz, 2H, fc), 5.11 (vt, J0 ¼ 2.1 Hz, 2H, fc), 6.29 (ddd, J ¼ 1.2, 6.5, 7.5 Hz, 1H, C6H4), 6.51 (td, J ¼ 1.6, 8.0 Hz, 1H, C6H4), 6.93 (td, J ¼ 1.0, 7.3 Hz, 1H, C6H4), 7.11 (dd, J ¼ 1.6, 7.5 Hz, 1H, C6H4), 7.60e7.72 (m, 10H, PPh2), 10.40 (s, 1H, NH). 31P{1H} NMR (dmso-d6): d 30.9 (s). IR (Nujol, cm1): 3200 br m, 1713 s, 1622 s, 1580 m, 1437 w, 1261 s, 1198 m, 1165 m, 1098 m, 1018 s, 997 w, 974 w, 932 w, 843 s, 745 s, 697 s, 658 s, 569 m, 519 w, 505 m, 487 m. ESI þ MS: m/z 695 ([5d  SbF6]þ). Anal. calc. for C34H34F6FeN2O2PPdSb (931.60): C 43.83, H 3.68, N 3.01%. Found: C 43.91, H 3.64, N 2.77%. 4.11. X-ray crystallography Single crystals of 1a were formed upon layering a chloroform solution of this compound with hexane and slow crystallization by liquid-phase diffusion. The phosphine oxides were crystallized similarly from ethyl acetate-hexane (2a and 2c) or chloroformhexane (2b). The latter, however, proved to be non-merohedral twins, and the collected diffraction data had to be corrected for twinning using the twin matrix (1 0 0; 0 1 0; 0.290 0.606 1). The refined contributions of the two contributing domains were approximately 0.72 and 0.28. Crystals of the Pd(II) complexes, predominantly in a solvated form (see below), were obtained in an analogous manner upon layering a solution of the complexes in a chlorinated solvent with a poor solvent (3b, 3d, and 4b: chloroform/pentane, 4b: chloroform/ hexane, 5a: chloroform/diethyl ether, 5b: dichloromethane/diethyl ether, and 5d: chloroform/diethyl ether and hexane). Single crystals of complex 3a (solvated) were obtained when a dichloromethane

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tova  et al. / Journal of Organometallic Chemistry xxx (2016) 1e15 H. Charva

solution of [PdCl2(cod)] was layered with ligand 1a dissolved in chloroform, and the burgundy red solution which resulted after several days was crystallized by the diffusion of diethyl ether added carefully as a top layer. Full-set diffraction data [qmax ¼ 26 (3a$2CHCl3) or 27.5 (all other compounds), completeness  99.2%] were collected at 150(2) K with a Nonius KappaCCD diffractometer equipped with an Apex II detector (Bruker) and Cryostream cooler (Oxford Cryosystems) using graphite-monochromated radiation (MoKa, l ¼ 0.71073 Å). The data were corrected for absorption by using the methods incorporated in the diffractometer software (implementations of the SADABS program [31]). The structures were solved by direct methods (SHELXS97 [32]) and refined by fullmatrix least squares based on F2 (SHELXL97 [32]). A summary of the relevant crystallographic data and structure refinement parameters is available as Supplementary information to this article (Table S1). All non-hydrogen atoms were refined with anisotropic displacement factors. Hydrogen atoms residing on the carbon atoms (CHn) were included in their theoretical positions using the standard HFIX instructions implemented in the SHELXL97 program and refined as riding atoms with Uiso(H) set to a multiple of Ueq(C) of their bonding atom. The NH hydrogens were identified on the difference maps and refined similarly with Uiso(H) ¼ 1.2Ueq(N). In the case of 5a$CHCl3, the terminal NHEt moiety was disordered and had to be modeled over two positions. The occupancies of the two orientations were refined to 14:86. A disorder was also detected in the crystal structure of 3b$2CHCl3, in which the Pdbound chloride ligands exert positional disorder resulting by rotation of the ClePdeCl0 moiety along the PePdeP0 axis (primelabeled atoms are generated by crystallographic inversion) and were refined over two positions (ratio 84:16) with equal anisotropic displacement parameters. Furthermore, the solvent molecules filling structural voids in the structures of solvated Pd(II) complexes were disordered in most cases and were treated with the SQUEEZE [33] procedure as incorporated in the PLATON program [34]. Depending on the extent of the disorder, this approach was applied either to all solvent molecules present in the structure (3a$2CHCl3, 3d$2CHCl3 and 5a$2CHCl3) or to the most disordered ones (one of the three CHCl3 molecules for 4a$3CHCl3 and one half of the CHCl3 molecule for 4b$2.5CHCl3 per the asymmetric unit). For the less disordered molecules, a refinement over two positions was used (4a$3CHCl3: one CHCl3 molecule; 5b$2CH2Cl2: both dichloromethane molecules). Geometric parameters and structural drawings presented in this paper were obtained with a recent version of the PLATON program [34]. All numerical values were rounded with respect to their estimated deviations (ESDs) given to one decimal place. Parameters relating to atoms in constrained positions (usually hydrogens) are quoted without their ESDs.

Acknowledgments The results reported in this paper were obtained with financial support from the Czech Science Foundation (project no. 1308890S).

Appendix A. Supplementary data CCDC 1441140e1441151 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via the Internet at http://www.ccdc.cam.ac.uk/.

Appendix B. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.jorganchem.2016.02.036. References e pni [1] P. St cka, Chem. Soc. Rev. 41 (2012) 4273. [2] a) A. Bader, E. Lindner, Coord. Chem. Rev. 108 (1991) 27; b) C.S. Slone, D.A. Weinberger, C.A. Mirkin, Prog. Inorg. Chem. 48 (1999) 233. [3] T.D. Nixon, A.J. Gamble, R.J. Thatcher, A.C. Whitwood, J.M. Lynam, Inorg. Chim. Acta 380 (2012) 252. gel, Å.S. Snygg, L. Gorton, [4] Representative examples: a) H. Bjelosevic, C. Spe S.K.C. Elmroth, T. Persson, Tetrahedron 62 (2006) 4519; b) L. Ropartz, N.J. Meeuwenoord, G.A. van der Marel, P.W.N.M. van Leeuwen, A.M.Z. Slawin, P.C.J. Kamer, Chem. Commun. (2007) 1556; c) M. Nuzzolo, A. Grabulosa, A.M.Z. Slawin, N.J. Meeuwenoord, G.A. van der Marel, P.C.J. Kamer, Eur. J. Org. Chem. (2010) 3229. [5] a) J.H. Yoon, Y.J. Park, J.H. Lee, J. Yoo, C.-H. Jun, Org. Lett. 7 (2005) 2889; b) J.-W. Park, J.-H. Park, C.-H. Jun, J. Org. Chem. 73 (2008) 5598. e , P. St pni [6] For representative recent examples, see: a) J. Schulz, I. Císarova cka, Organometallics 31 (2012) 729; e pni b) J. Tauchman, B. Therrien, G. Süss-Fink, P. St cka, Organometallics 31 (2012) 3985; e pni c) J. Schulz, I. Císarov a, P. St cka, Eur. J. Inorg. Chem. (2012) 5000; e pni d) J. Tauchman, G. Süss-Fink, P. St cka, O. Zava, P.J. Dyson, J. Organomet. Chem. 723 (2013) 233; e pni e) P. St cka, B. Schneiderov a, J. Schulz, I. Císarov a, Organometallics 32 (2013) 5754; e , P. St pni f) J. Tauchman, I. Císarova cka, Dalton Trans. 43 (2014) 1599; e , T. Riedel, P.J. Dyson, P. St pni g) J. Schulz, J. Tauchman, I. Císarova cka, J. Organomet. Chem. 751 (2014) 604; e pni h) P. St cka, M. Verní cek, J. Schulz, I. Císarov a, J. Organomet. Chem. 755 (2014) 41;  e , I. Císarova , F. Uhlík, M. Stícha, pni i) T.A. Fernandes, H. Solarova P. St cka, Dalton Trans. 44 (2015) 3092. e , P. St pni [7] H. Solarov a, I. Císarova cka, Organometallics 33 (2014) 4131.  e , P. St pni [8] K. Skoch, I. Císarova cka, Organometallics 34 (2015) 1942. [9] L. Chen, Q. Wang, R. Huang, C. Mao, J. Shang, H. Song, Appl. Organomet. Chem. 19 (2005) 45. [10] a) H.H. Lau, H. Hart, J. Org. Chem. 24 (1959) 280; b) A. Federman Neto, J. Miller, V. Faria de Andrade, S.Y. Fujimoto, M. Maísa de  Freitas Afonso, F.C. Archanjo, V.A. Darin, M.L. Andrade e Silva, A.D.L. Borges, G. Del Ponte, Z. Anorg. Allg. Chem. 628 (2002) 209; c) B. Schetter, B. Speiser, J. Organomet. Chem. 689 (2004) 1472. e pni [11] a) M. Lama c, J. Cva cka, P. St cka, J. Organomet. Chem. 693 (2008) 3430; e pni b) M. Lama c, I. Císarov a, P. St cka, New J. Chem. 33 (2009) 1549.   [12] J. Lapi c, V. Havai c, D. Saki c, K. Sankovi c, S. Djakovi c, V. Vr cek, Eur. J. Org. Chem. (2015) 5424. [13] For an overview of the chemistry of 10 -functionalized phosphinoferrocene e pni donors, see: P. St cka, 10 -Functionalised ferrocene phosphines: synthesis, e pni coordination chemistry and catalytic applications, in: P. St cka (Ed.), Ferrocenes: Ligands, Materials and Biomolecules, Wiley, Chichester, 2008, pp. 177e204 (chapter 5). e pni , J. Organomet. Chem. 696 (2011) 3727. [14] P. St cka, H. Solarov a, I. Císarova [15] H.-O. Kalinowski, S. Berger, S. Braun, 13C-NMR-Spektroskopie, Thieme Verlag, Stuttgart, 1984 (chapter 4). [16] F.H. Allen, O. Kennard, D.G. Watson, L. Brammer, A.G. Orpen, R. Taylor, J. Chem. Soc. Perkin Trans. II e Suppl. (1987) S1. e pni [17] a) J. Kühnert, M. Dusek, J. Demel, H. Lang, P. St cka, Dalton Trans. (2007) 2802; e , M. Lama pni b) J. Kühnert, I. Císarova c, P. St cka, Dalton Trans. (2008) 2454; e , P. St pni c) J. Tauchman, I. Císarova cka, Organometallics 28 (2009) 3288; e pni d) J. Schulz, I. Císarov a, P. St cka, J. Organomet. Chem. 694 (2009) 2519 and also refs. [6a,c,e,f,i] and [7]. [18] V. Munyejabo, M. Postel, J.L. Roustan, C. Bensimon, Acta Crystallogr. Sect. C. Struct. Chem. 50 (1994) 224. e pni , Organometallics 15 (1996) 543. [19] J. Podlaha, P. St cka, J. Ludvík, I. Císarova e pni , J. Schulz, Organometallics 30 (2011) 4393. [20] P. St cka, I. Císarova [21] K.S. Gan, T.S.A. Hor, in: A. Togni, T. Hayashi (Eds.), Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science, VCH, Weinheim, 1995, pp. 3e104 ch. 1. [22] a) J.V. Quagliano, L. Schubert, Chem. Rev. 50 (1952) 201; b) T.G. Appleton, H.C. Clark, L.E. Manzer, Coord. Chem. Rev. 10 (1973) 335; c) F.R. Hartley, Chem. Soc. Rev. 2 (1973) 163. [23] R.G. Pearson, Inorg. Chem. 12 (1973) 712. [24] J. Vicente, A. Arcas, D. Bautista, P.G. Jones, Organometallics 16 (1997) 2127. e pni [25] P. St cka, J. Podlaha, R. Gyepes, M. Pol asek, J. Organomet. Chem. 552 (1998) 293. e pni , M. Lama [26] P. St cka, H. Solarova c, I. Císarov a, J. Organomet. Chem. 695 (2010) 2423. [27] Compare the values of total puckering amplitude (Q) and the 4 angle, Q/4: 0.459(3) Å/41.6(3) for 4a$3CHCl3, 0.423(2) Å/225.3(3) for 4b$2.5CHCl3,

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tova  et al. / Journal of Organometallic Chemistry xxx (2016) 1e15 H. Charva 0.461(2) Å/38.5(3) for 5a$CHCl3, 0.428(2) Å/44.4(3) for 5b$2CH2Cl2, and 0.502(2) Å/207.4(3) for 5d. (ideal envelope requires 4 ¼ k 36 , where k ¼ 0, 1, 2, etc.). For reference, see: D. Cremer, J.A. Pople J. Am. Chem. Soc. 97 (1975) 1354. [28] Although the individual ring puckering parameters can be regarded dubious due to a large variation of the individual in-ring distances, they pertain to identical moieties and their trends are therefore meaningful. [29] Additional CeH/F interactions are detected in the crystal structures of 5a$CHCl3, 5b$2CH2Cl2, and 5d.

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[30] A.C. Cope, E.C. Friedrich, J. Am. Chem. Soc. 90 (1968) 909. [31] SADABS, Bruker AXS Area Detector Scaling and Absorption Correction (Various Recent Versions), Bruker AXS Inc., Madison, USA, 2014-2015. [32] G.M. Sheldrick, Acta Crystallogr. Sect. A Found. Crystallogr. 64 (2008) 112. [33] P. van der Sluis, A.L. Spek, Acta Crystallogr. Sect. A Found. Crystallogr. 46 (1990) 194. [34] a) A.L. Spek, PLATON, a Multipurpose Crystallographic Tool, Utrecht University, Utrecht, The Netherlands, 2010; b) A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7.

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