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Synthesis and crystal structures of palladium(II) complexes containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide
Polyhedron 21 (2002) 843 /848 www.elsevier.com/locate/poly
Synthesis and crystal structures of palladium(II) complexes containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide Masakazu Kita a,*, Shin-ichi Abiko a, Akira Fuyuhiro b, Kazuaki Yamanari b, Katsuo Murata a, Shinsuke Yamashita a b
a Chemistry Department, Naruto University of Education, Takashima, Naruto 772-8502, Japan Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
Received 14 September 2001; accepted 8 January 2002
Abstract Four palladium(II) complexes [PdX2(L-N ,S )] (X/Cl, Br; L: BzSq /benzyl 8-quinolyl sulfide, PheneSq /phenethyl 8-quinolyl sulfide) were prepared. The crystal structure of [PdCl2(BzSq-N ,S )] revealed the presence of an intraligand stacking between the phenyl and quinolyl groups of BzSq. This stacking interaction was confirmed even in Me2SO, MeCN and MeNO2. On the other hand, [PdCl2(PheneSq-N ,S )] did not show such an intraligand stacking both in the solid and in solutions. # 2002 Published by Elsevier Science Ltd. Keywords: Palladium(II) complexes; Benzyl 8-quinolyl sulfide; Phenethyl 8-quinolyl; Crystal structures
1. Introduction Aromatic interactions such as face-to-face p /p, faceto-edge p /p, and CH-p play an important role in molecular recognition [1]. Such interactions have been found in many coordination compounds. For example, there is a face-to-face interligand stacking between a phenyl group of 1,2-bis(diphenylphosphino)ethane (dppe) and an acetylacetonato (acac) ring in cis [Co(CN)2(acac)(dppe)] in the solid [2]. This stacking mode is confirmed in CHCl3 by its 1H NMR spectrum. Similar p/p stacking phenomena in the solid have been reported in [Cu(bpy)(L-tyr)(ClO4-O )] (bpy /2,2?-bipyridine and L-tyr /L-tyrosine) [3], [Pd(bpy)(L-tyr ×/gly)]×/ 3H2O (L-tyr ×/gly /L-tyrosylglycine) [4], [Cu(bpy)(Ltrp)]ClO4 (L-trp /L-tryptophan) [5]. Here we report the synthesis of four palladium(II) complexes [PdX2(L-N ,S )] (X /Cl, Br; L: BzSq /benzyl 8-quinolyl sulfide, PheneSq /phenethyl 8-quinolyl sulfide) and examine whether there are any intra- and/or
* Corresponding author. Tel.: 81-886-87-1311; fax: 81-886-871090. E-mail address: [email protected] (M. Kita).
interligand stacking interactions for these complexes both in solid and in several solvents.
2. Experimental 2.1. BzSq An ethanol solution (30 cm3) containing 1.0 g of 8quinolinethiol (5.1 mmol) and 0.64 g of benzyl chloride (5.1 mmol) was refluxed for 24 h, until the initial yellow color disappeared. After cooling, white needlelike crystals were obtained by addition of 100 cm3 of water. Yield: 1.1 g (86%). Found: C, 75.75; H, 5.24; N, 5.51%. Calc. for C16H13NS: C, 75.85; H, 5.94; N, 5.53%. NMR: dH (J (Hz), d6-DMSO) 8.89(dd, J2 3 /4.1, J2 4 /1.4; 1H, H(2)), 8.35(dd, J3 4 /8.3, J2 4 /1.4; 1H, H(4)), 7.72(d, J5 6 /8.0; 1H, H(5)), 7.63(d, J6 7 /7.3; 1H, H(7)), 7.58(q, J2 3 /4.1, J3 4 /8.3; 1H, H(3)), 7.52(t, J5 6 /8.0, J6 7 /7.3; 1H, H(6)), 7.49(d, J12 13 /7.9; 2H, H(12) and H(16)), 7.34(t, J12 13 /7.9, J13 14 /8.1; 2H, H(13) and H(15)), 7.29(t, J13 14 /8.1, J14 15 /8.1; 1H, H(14)), 4.34(s; 2H, H(21)); dC(d6-DMSO) 149.2(C(2)), 144.5(C(10)), 138.2(C(9)), 137.0(C(11)), 136.3(C(4)), 128.8(C(12) and C(16)), 128.4(C(13) and
0277-5387/02/$ - see front matter # 2002 Published by Elsevier Science Ltd. PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 0 8 6 4 - 1
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(C(15)), 127.7(C(8)), 127.0(C(14)), 126.6(C(6)), 124.0(C(7)), 123.9(C(5)), 121.9(C(3)), 34.3(C(21)). 2.2. PheneSq To an ethanol solution (30 cm3) containing 1.0 g of 8quinolinethiol (5.1 mmol) and 0.71 g of 2-chloroethyl-
benzene (5.1 mmol) was added a solution of sodium hydroxide (0.45 g, 10.2 mmol) in 50 cm3 of water. The mixture was refluxed for 24 h and 100 cm3 of diethyl ether was added to it. The diethyl ether extract was evaporated to remove diethyl ether. The crude oily residue, which showed a desirable 1H NMR spectrum, was used for the preparations without further purification. Yield: 1.1 g (82%).
Table 1 Crystallographic data Complex
[PdCl2(BzSq)]
[PdCl2(PheneSq)]× CH2Cl2
Formula Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) Z ˚ )3 V (A Dcalc (g cm 3) m (Mo Ka) (cm 1) Transmission factor Crystal color Crystal habit Crystal size (mm) Scan type 2u max (8) Reflections measured Number of reflections measured Number of reflections observed [½Fo½ 6s (½Fo½) R Rw W
C16H13NSCl2Pd triclinic P/1¯ (#2) 15.601(2) 13.316(3) 9.160(2) 70.08(2) 83.19(1) 66.68(1) 4 1642.7(6) l.733 15.73 0.776 /1.000 pale yellow prismatic 0.20 0.12 0.25 v /2u 60 9h , 9k , l 7890
C18H17NSCl4Pd triclinic P/1¯ (#2) 10.638(1) 11.156(1) 9.999(1) 114.980(7) 107.346(8) 75.454(8) 2 1016.0(2) 1.725 15.43 0.85 /1.00 yellow /orange prismatic 0.25 0.25 0.40 v /2u 60 h , 9k , 9l 6205
4900
4942
0.032 0.039 1/s 2(½Fo½)2
0.041 0.057 1/s 2(½Fo½)2
Fig. 1.
ORTEP
3. Preparation of complexes
3.1. [PdX2(BzSq)](X /Cl and Br) To a solution of Na2[PdCl4] ×/H2O (0.52 g, 1.7 mmol) in 50 cm3 of ethanol was added a solution of BzSq (0.43 g, 1.7 mmol) in 50 cm3 of ethanol. After stirring at room temperature (r.t.), the resulting orange precipitate was filtered and recrystallized from CH2Cl2. Yield: 0.31 g (43%). Found: C, 45.08; H, 2.95; N, 3.25%. Calc. for [PdCl2(BzSq)] /C16H13Cl2PdNS: C, 44.83; H, 3.06; N, 3.27%. Its NMR data is shown in Table 3. The corresponding dibromo complex was prepared from K2[PdBr4] in a similar way. Yield: 0.18 g (88%). Found: C,36.51; H, 2.53; N, 2.47%. Calc. for [PdBr2(BzSq)] / C16H13Br2PdNS: C, 37.13; H, 2.53; N, 2.71%. NMR: dH(J (Hz), d6-DMSO) 9.62(d, J2 3 /5.0; 1H, H(2)), 8.75(d, J3 4 /8.3; 1H, H(4)), 8.32(d, J6 7 /7.5; 1H, H(7)), 8.27(d, J5 6 /7.7; 1H, H(5)), 7.92(t, J5 6 /7.7, J6 7 /7.5; 1H, H(6)), 7.74(t, J2 3 /5.0, J3 4 /8.3; 1H, H(3)), 7.21(t, J12 13 /6.8; 2H, H(12) and H(16)), 7.09 / 6.98 (m; 3H, H(13) /H(15)), 4.76(d, J /12.9; 1H, H(21a)), 4.59(d, J /12.9; 1H, H(21b)); dC(d6-DMSO) 155.8(C(2)), 130.9(C(9)), 130.6(C(12) and C(16)),
[8] drawings of [PdCl2(BzSq)] and its intraligand stacking.
M. Kita et al. / Polyhedron 21 (2002) 843 /848
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Table 3 NMR data of [PdCl2(BzSq)] in d6-DMSO
1
Fig. 2. ORTEP [8] drawings of [PdCl2(PheneSq)] and its interligand stacking. Table 2 ˚ ) and bond angles (8) for [PdCl2(BzSq or Selected bond distances (A PheneSq)] [PdCl2(BzSq )] Bond lengths Pd(1) Cl(1) Pd(1) Cl(2) Pd(1) S(1) Pd(1) N(1) S(1) C(8) S(1) C(10) C(10) C(11)
2.315 2.293(1) 2.248(1) 2.046(3) 1.780(4) 1.848(5) 1.489(7)
Pd(2) Cl(21) Pd(2) Cl(22) Pd(2) S(2) Pd(2) N(2) S(2) C(28) S(2) C(30) C(30) C(31)
2.311(1) 2.283(1) 2.237(1) 2.036(4) 1.752(7) 1.832(5) 1.489(7)
Bond angles Cl(1) Pd(1) Cl(2) Cl(1) Pd(1) S(1) Cl(1) Pd(1) N(1) Cl(2) Pd(1) S(1) Cl(2) Pd(1) N(1) S(1) Pd(1) N(1) Pd(1) S(1) C(8) Pd(1) S(1) C(10) C(8) S(1) C(10) S(1) C(10) C(11)
91.07(4) 177.45(5) 95.65(9) 87.18(4) 172.74(9) 86.01(9) 99.1(1) 104.5(2) 100.3(2) 115.3(3)
Cl(21) Pd(2) Cl(22) Cl(21) Pd(2) S(2) Cl(21) Pd(2) N(2) Cl(22) Pd(2) S(2) Cl(22) Pd(2) N(2) S(2) Pd(2) N(2) Pd(2) S(2) C(28) Pd(2) S(2) C(30) C(28) S(2) C(30) S(2) C(30) C(31)
91.28(5) 177.63(5) 95.6(1) 86.69(5) 173.1(1) 86.5(1) 99.0(2) 107.9(2) 101.6(2) 115.3(3)
[PdCl2(pheneSq )] Bond lengths Pd(1) Cl(1) Pd(1) Cl(2) Pd(1) S(1) Pd(1) N(1) S(1) C(8) S(1) C(10) C(10) C(20) C(20) C(11)
2.315(1) 2.287(1) 2.2530(9) 2.036(3) 1.775(4) 1.828(4) 1.507(6) 1.519(2)
Bond angles Cl(1) Pd(1) Cl(2) Cl(1) Pd(1) S(1) Cl(1) Pd(1) N(1) Cl(2) Pd(1) S(1) Cl(2) Pd(1) N(1) S(1) Pd(1) N(1) Pd(1) S(1) C(8) Pd(1) S(1) C(10) C(8) S(1) C(10) S(1) C(10) C(20) C(10) C(20) C(11)
91.60(4) 174.96(4) 94.52(8) 87.96(4) 172.42(8) 86.33(8) 98.9(1) 106.7(1) 102.4(2) 113.5(2) 111.4(3)
13
H NMR
C NMR
Position
d (J /Hz)
Position
d
2 4 7 5 6 3 12,16 13,14,15 21a 21b
9.42(d, J2 3 5.2; 1H) 8.74(d, J3 4 8.2; 1H) 8.32(d, J6 7 7.4; 1H) 8.27(d, J5 6 8.0; 1H) 7.92(t, J5 6 8.0, J6 7 7.4; 1H) 7.74(t, J2 3 5.2, J3 4 8.2; 1H) 7.27(t, J12 13 6.1; 2H) 7.08 /7.00(m; 3H) 4.69(d, J 12.9; 1H) 4.51(d, J 12.9; 1H)
2 10 4 7 11 5 9 12,16 6 14 13,15 8 3 21
153.6 150.5 1470.7 136.9 133.4 131.6 130.2 130.1 128.6 128.4 127.9 126.1 123.2 47.2
129.3(C(6)), 129.0(C(14)), 128.5(C(13) and C(15)), 127.9(C(8)), 124.1(C(3)), 48.3(C(21)). 3.2. [PdX2(PheneSq)](X /Cl and Br) To a solution of Na2[PdCl4] ×/H2O (0.24 g, 0.8 mmol) in 50 cm3 of ethanol was added a solution of PheneSq (0.21 g, 0.8 mmol) in 50 cm3 of ethanol. After stirring at r.t., the resulting orange precipitate was filtered and recrystallized from CH2Cl2. Yield: 0.30 g (85%). Found: C, 40.88; H, 3.19; N, 2.70%. Calc. for [PdCl2(PheneSq)] /C17H15Cl2PdNS: C, 40.97; H, 3.25; N, 2.65%. Its NMR data is shown in Table 4. The corresponding dibromo complex was prepared from K2[PdBr4] in a similar way. Yield: 0.38 g (88%). Found: C,36.92; H, 2.77; N, 2.38%. Calc. for [PdBr2(PheneSq)] /C17H15Br2PdNS: C, 38.41; H, 2.84; N, 2.64%. NMR: dH(J (Hz), d6-DMSO) 10.14 (d, J2 3 / 5.3; 1H, H(2)), 8.48 (d, J3 4 /8.2; 1H, H(4)), 8.04(d, J5 6 /7.5, J6 7 /7.2; 2H, H(7) and H(5)), 7.76(t, J5 6 /7.2, J6 7 /7.2; 1H, H(6)), 7.67(q, J2 3 /5.3, J3 4 /8.2; 1H, H(3)), 7.07(d, J/3.9; 5H, H(12)/ H(16)), 3.83(d, J/11.9; 1H, H(22)), 3.58(s; 2H, H(22)), 3.01(d, J/11.9; 1H, H(21b)); dC(d6-DMSO) 156.9(C(2)), 150.4(C(10)),140.4(C(4)), 137.5(C(7)), 135.7(C(11)), 131.7(C(5)), 130.2(C(8)), 129.2(C(6)),
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129.1(C(12) and C(16)), 128.8(C(13) and C(15)), 127.3(C(14)), 124.2(C(3)), 45.4(C(21)), 36.5(C(22)).
4. Crystallography Single crystals of [PdCl2(BzSq)] (0.25/0.20 /0.12 mm) and [PdCl2(PheneSq)] (0.40 /0.25 /0.25 mm) were fixed on the end of a glass fiber with epoxy resin. They were mounted on a Rigaku AFC-7R diffractometer and the diffraction data were collected at 298 K with graphite-monochromated Mo Ka radiation (l/ ˚ ) using v /2u scan mode. Cell dimensions 0.71069 A were determined by least-squares refinement of the angular positions of 25 independent reflections in the range 28 B/2u B/398 for each sample. Crystallographic data and experimental details are listed in Table 1. The position of the palladium was determined by direct methods (SHELXS-86 [6]) for each complex and the remaining non-hydrogen atoms were located by subsequent Fourier syntheses. The structure was refined on F
by full-matrix least-square techniques with anisotropic thermal parameters for non-hydrogen atoms. Hydrogen atoms were located at positions determined by Fourierdifference syntheses or by calculations. All calculations were carried out with the TEXAN [7] software.
5. Measurement UV /Vis absorption spectra were recorded on an Hitachi U-3400 spectrophotometer, 1H and 13C NMR spectra with a Bruker ARX300 spectrometer. X-Ray crystal analysis was made at the X-ray Diffraction Service of the Department of Chemistry of Osaka University.
6. Results and discussion Neutral complexes [PdX2(L)] (X /Cl or Br-; L / BzSq or PheneSq) were obtained in high yields by the
Fig. 3. Proton NMR spectra of [PdCl2(BzSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric constant of solvent.
M. Kita et al. / Polyhedron 21 (2002) 843 /848 Table 4 NMR data of [PdCl2(pheneSq)] in DMSO
1
13
H NMR
C NMR
Position
d (J /Hz)
Position
d
2 4 7,5 6 3 12,13 14 15,16
9.90(d, J2 3 5.3, J2 4 1.5; 1H) 8.48(d, J3 4 8.3, J2 4 1.5; 1H) 8.03(d, J3 6 7.8, J6 7 7.8; 2H) 7.78(t, J5 6 7.8, J6 7 7.8; 1H) 7.68(q, J2 3 5.3, J3 4 8.3; 1H) 7.11 /7.03(m; 5H) 3.77 /3.46(m; 3H) 3.11 /3.02(m; 1H)
2 10 4 7 11 5 9 6 12,16 8 13,15 14 3 21 22
155.3 150.4 140.6 137.5 135.5 131.7 131.3 129.2 129.1 128.9 128.8 127.4 124.0 45.1 36.3
reaction of [PdX4]2 with sulfide ligands. They were characterized by NMR spectroscopy and elemental analysis. X-ray crystal structures were determined for [PdCl2(BzSq)] and [PdCl2(PheneSq)]. ORTEP [8] drawings of the present complexes are shown in Figs. 1 and 2. Selected bond distances and angles are listed in Table 2. Though there are two similar but independent molecules in [PdCl2(BzSq)], we describe only the structure of Pd(1) hereafter. The BzSq ligand coordinates bidentately through the N,S donors. The Pd /Cl bond distance trans to the ˚ , which is sulfur in [PdCl2(BzSq-N ,S )] is 2.315(1) A ˚ than the Pd /Cl one trans to imine. longer by 0.022(1) A ˚] A similar lengthening of the Pd /Cl bond [0.028(1) A was also observed in [PdCl2(PheneSq-N ,S )]. This bond weakening is known as trans influence [9]. The ligand bite angles [BzSq /86.01(9)8 and PheneSq/86.33(8)8] are normal and typical values. A remarkable feature is the presence of an intraligand stacking interaction between the phenyl group and the quinolyl of BzSq (see Fig. 1(a) (left)). The angle between the phenyl plane and the quinolyl is 46.68. The top view indicates clearly the superimposition between the phenyl group and the quinolyl (Fig. 1(b) (right)). The C(8) /S /C(10) angle of 100.3(2)8 is considerably less than a tetrahedral angle of
847
109.58, which is reasonably ascribed to the intraligand stacking interaction of BzSq. The dihedral angle C(8) / S /C(10) /C(11) is 43.9(4)8. The distance between C(11) and C(9) is 3.60(1) A˚, which is the standard value for a p /p distance. This stacking conformation generates the repulsive interactions of Pd /Cl(2)/ /H /C(10) 3.41(2) A˚ and Pd/ /H/C(12) 2.99(2) A˚ [11]. Interligand stacking interactions between a phenyl group and another ligand (for example, bpy) in a given complex have been often reported [2 /5] but intraligand stacking in the same ligand described here seems to be quite rare. There is no intermolecular stacking interaction between aromatic rings in the present complex. On the other hand, [PdCl2(PheneSq-N ,S )] does not show such an intraligand stacking mode (Fig. 2(a) (left)). In general, a long alkyl chain is apt to adopt an anti conformation, that is, trans conformation, due to the repulsion between adjacent methylene protons. The C(8)-S-C(10) /C(11) dihedral angle is 56.3(4)8 and the S /C(10) /C(20)/C(11) one is 173.4(3)8. The S /CH2 / CH2 /C sequence takes an anti conformation, so that the phenyl group becomes apart from the quinolyl. This is the reason why the PheneSq complex does not have an intraligand stacking mode. Instead there is an intermolecular stacking interaction between two quinolyl groups of adjacent molecules as shown in Fig. 2(b) (right). The distance between the quinolyl planes 3.40(1) ˚ is considerably shorter than the standard value (3.60 A ˚ ) for a p /p distance. Since the crystallographic A inversion is located at the center of the intermolecular quinolyl stacking, the angle between two quinolyl planes becomes 08. The assignments of 1H and 13C NMR signals were carried out by proton homo-decoupling, 1H-detected multiple quantum coherence (HMQC), and 1H-detected multiple bondquantum coherence (HMBC) spectra. The results are listed in Tables 3 and 4. In the 1H NMR spectrum of [PdCl2(BzSq-N ,S )] an interesting splitting was observed: the phenyl proton signals are split into two groups, the group of H(12) and H(16) (d 7.21) and one of H(13), H(14) and H(15) (d 7.09 /6.98), in d6-Me2SO as shown in Fig. 3. The free BzSq in d6-Me2SO shows the phenyl protons at d7.49 (H(12) and H(16)), d 7.34 (H(13) and H(15)), and d 7.29 (H(14)). The changes of chemical shifts on complexation can be related to the ring current effect [10] of pelectrons of the quinolyl group by the aromatic intraligand interaction in d6-Me2SO. Similar changes were observed in CD3OD (7.02 and 6.84) (Fig. 3). On the other hand, the signals of H(13), H(14), H(15) appear at relatively low magnetic field and the chemical shift separations are negligible in CD2Cl2 (d 7.2) or CDCl3 (d 7.2) with low dielectric constants. This result suggests that the aromatic intraligand interaction is recognized in high dielectric solvents and does not occur in low dielectric solvents.
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Fig. 4. Proton NMR spectra of [PdCl2(PheneSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric constant of solvent.
Similar 1H NMR measurements were carried out for [PdCl2(pheneSq-N ,S )]. However, this complex did not show any splitting of the phenyl proton signals as shown in Fig. 4. Thus, the aromatic intraligand interaction could not be observed in the crystal and in solvents. Each dibromo complex [PdBr2(BzSq)] or [PdBr2(PheneSq)] showed the same results as the corresponding dichloro complex. Hence we conclude that [PdBr2(BzSq)] also has a similar noble intraligand stacking interaction as [PdCl2(BzSq)] does in solid and in solvents with high dielectric constants.
7. Supplementary material Crystallographic data have been deposited with the CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: /44-1223-366033; e-mail: [email protected] or www: http://www.ccdc.cam.ac.uk) and are available on request quoting the deposition numbers 169087 for [PdCl2(BzSq)] and 169088 for [PdCl2(pheneSq)].
References [1] (a) C.A. Hunter, Chem. Soc. Rev. (1994), 101, and references therein.; (b) M. Mishio, M. Hirota, Y. Umezawa, The CH /p Interaction, Wiley-VCH, 1998; (c) A. Magistrato, M. Merlin, O.S. Pregosin, U. Rothlisberger, Organometallics 19 (2000) 3591. [2] M. Kita, K. Kashiwabara, J. Fujita, Bull. Chem. Soc. Jpn. 61 (1988) 3187. [3] H. Masuda, T. Sugimori, A. Odani, O. Yamauchi, Inorg. Chim. Acta 180 (1991) 73. [4] T. Sugimori, K. Shibakawa, H. Masuda, A. Odani, O. Yamauchi, Inorg. Chem. 32 (1993) 4951. [5] O. Yamauchi, A. Odani, H. Masuda, Inorg. Chim. Acta 198 /200 (1992) 749. [6] G.M. Sheldrick, SHELXS-86, Program for Crystal Structure Determination, University of Go¨ttingen, 1986. [7] TEXSAN, Crystal Structure Analysis Package, Molecular Structure Corporation, 1985 and 1992. [8] C.K. Johnson, ORTEP-II. Report ORNL-5138, Oak Ridge National Laboratory, Oak Ridge, TN, 1976. [9] M. Kita, K. Kashiwabara, Polyhedron 16 (1997) 2771. [10] A. Odani, S. Deguchi, O. Yamauchi, Inorg. Chem. 25 (1986) 62. ˚ are absent in [11] Such repulsive interactions within 3.60 A [PdCl2(pheneSq)].
Synthesis and crystal structures of palladium(II) complexes containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide Masakazu Kita a,*, Shin-ichi Abiko a, Akira Fuyuhiro b, Kazuaki Yamanari b, Katsuo Murata a, Shinsuke Yamashita a b
a Chemistry Department, Naruto University of Education, Takashima, Naruto 772-8502, Japan Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
Received 14 September 2001; accepted 8 January 2002
Abstract Four palladium(II) complexes [PdX2(L-N ,S )] (X/Cl, Br; L: BzSq /benzyl 8-quinolyl sulfide, PheneSq /phenethyl 8-quinolyl sulfide) were prepared. The crystal structure of [PdCl2(BzSq-N ,S )] revealed the presence of an intraligand stacking between the phenyl and quinolyl groups of BzSq. This stacking interaction was confirmed even in Me2SO, MeCN and MeNO2. On the other hand, [PdCl2(PheneSq-N ,S )] did not show such an intraligand stacking both in the solid and in solutions. # 2002 Published by Elsevier Science Ltd. Keywords: Palladium(II) complexes; Benzyl 8-quinolyl sulfide; Phenethyl 8-quinolyl; Crystal structures
1. Introduction Aromatic interactions such as face-to-face p /p, faceto-edge p /p, and CH-p play an important role in molecular recognition [1]. Such interactions have been found in many coordination compounds. For example, there is a face-to-face interligand stacking between a phenyl group of 1,2-bis(diphenylphosphino)ethane (dppe) and an acetylacetonato (acac) ring in cis [Co(CN)2(acac)(dppe)] in the solid [2]. This stacking mode is confirmed in CHCl3 by its 1H NMR spectrum. Similar p/p stacking phenomena in the solid have been reported in [Cu(bpy)(L-tyr)(ClO4-O )] (bpy /2,2?-bipyridine and L-tyr /L-tyrosine) [3], [Pd(bpy)(L-tyr ×/gly)]×/ 3H2O (L-tyr ×/gly /L-tyrosylglycine) [4], [Cu(bpy)(Ltrp)]ClO4 (L-trp /L-tryptophan) [5]. Here we report the synthesis of four palladium(II) complexes [PdX2(L-N ,S )] (X /Cl, Br; L: BzSq /benzyl 8-quinolyl sulfide, PheneSq /phenethyl 8-quinolyl sulfide) and examine whether there are any intra- and/or
* Corresponding author. Tel.: 81-886-87-1311; fax: 81-886-871090. E-mail address: [email protected] (M. Kita).
interligand stacking interactions for these complexes both in solid and in several solvents.
2. Experimental 2.1. BzSq An ethanol solution (30 cm3) containing 1.0 g of 8quinolinethiol (5.1 mmol) and 0.64 g of benzyl chloride (5.1 mmol) was refluxed for 24 h, until the initial yellow color disappeared. After cooling, white needlelike crystals were obtained by addition of 100 cm3 of water. Yield: 1.1 g (86%). Found: C, 75.75; H, 5.24; N, 5.51%. Calc. for C16H13NS: C, 75.85; H, 5.94; N, 5.53%. NMR: dH (J (Hz), d6-DMSO) 8.89(dd, J2 3 /4.1, J2 4 /1.4; 1H, H(2)), 8.35(dd, J3 4 /8.3, J2 4 /1.4; 1H, H(4)), 7.72(d, J5 6 /8.0; 1H, H(5)), 7.63(d, J6 7 /7.3; 1H, H(7)), 7.58(q, J2 3 /4.1, J3 4 /8.3; 1H, H(3)), 7.52(t, J5 6 /8.0, J6 7 /7.3; 1H, H(6)), 7.49(d, J12 13 /7.9; 2H, H(12) and H(16)), 7.34(t, J12 13 /7.9, J13 14 /8.1; 2H, H(13) and H(15)), 7.29(t, J13 14 /8.1, J14 15 /8.1; 1H, H(14)), 4.34(s; 2H, H(21)); dC(d6-DMSO) 149.2(C(2)), 144.5(C(10)), 138.2(C(9)), 137.0(C(11)), 136.3(C(4)), 128.8(C(12) and C(16)), 128.4(C(13) and
0277-5387/02/$ - see front matter # 2002 Published by Elsevier Science Ltd. PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 0 8 6 4 - 1
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(C(15)), 127.7(C(8)), 127.0(C(14)), 126.6(C(6)), 124.0(C(7)), 123.9(C(5)), 121.9(C(3)), 34.3(C(21)). 2.2. PheneSq To an ethanol solution (30 cm3) containing 1.0 g of 8quinolinethiol (5.1 mmol) and 0.71 g of 2-chloroethyl-
benzene (5.1 mmol) was added a solution of sodium hydroxide (0.45 g, 10.2 mmol) in 50 cm3 of water. The mixture was refluxed for 24 h and 100 cm3 of diethyl ether was added to it. The diethyl ether extract was evaporated to remove diethyl ether. The crude oily residue, which showed a desirable 1H NMR spectrum, was used for the preparations without further purification. Yield: 1.1 g (82%).
Table 1 Crystallographic data Complex
[PdCl2(BzSq)]
[PdCl2(PheneSq)]× CH2Cl2
Formula Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) Z ˚ )3 V (A Dcalc (g cm 3) m (Mo Ka) (cm 1) Transmission factor Crystal color Crystal habit Crystal size (mm) Scan type 2u max (8) Reflections measured Number of reflections measured Number of reflections observed [½Fo½ 6s (½Fo½) R Rw W
C16H13NSCl2Pd triclinic P/1¯ (#2) 15.601(2) 13.316(3) 9.160(2) 70.08(2) 83.19(1) 66.68(1) 4 1642.7(6) l.733 15.73 0.776 /1.000 pale yellow prismatic 0.20 0.12 0.25 v /2u 60 9h , 9k , l 7890
C18H17NSCl4Pd triclinic P/1¯ (#2) 10.638(1) 11.156(1) 9.999(1) 114.980(7) 107.346(8) 75.454(8) 2 1016.0(2) 1.725 15.43 0.85 /1.00 yellow /orange prismatic 0.25 0.25 0.40 v /2u 60 h , 9k , 9l 6205
4900
4942
0.032 0.039 1/s 2(½Fo½)2
0.041 0.057 1/s 2(½Fo½)2
Fig. 1.
ORTEP
3. Preparation of complexes
3.1. [PdX2(BzSq)](X /Cl and Br) To a solution of Na2[PdCl4] ×/H2O (0.52 g, 1.7 mmol) in 50 cm3 of ethanol was added a solution of BzSq (0.43 g, 1.7 mmol) in 50 cm3 of ethanol. After stirring at room temperature (r.t.), the resulting orange precipitate was filtered and recrystallized from CH2Cl2. Yield: 0.31 g (43%). Found: C, 45.08; H, 2.95; N, 3.25%. Calc. for [PdCl2(BzSq)] /C16H13Cl2PdNS: C, 44.83; H, 3.06; N, 3.27%. Its NMR data is shown in Table 3. The corresponding dibromo complex was prepared from K2[PdBr4] in a similar way. Yield: 0.18 g (88%). Found: C,36.51; H, 2.53; N, 2.47%. Calc. for [PdBr2(BzSq)] / C16H13Br2PdNS: C, 37.13; H, 2.53; N, 2.71%. NMR: dH(J (Hz), d6-DMSO) 9.62(d, J2 3 /5.0; 1H, H(2)), 8.75(d, J3 4 /8.3; 1H, H(4)), 8.32(d, J6 7 /7.5; 1H, H(7)), 8.27(d, J5 6 /7.7; 1H, H(5)), 7.92(t, J5 6 /7.7, J6 7 /7.5; 1H, H(6)), 7.74(t, J2 3 /5.0, J3 4 /8.3; 1H, H(3)), 7.21(t, J12 13 /6.8; 2H, H(12) and H(16)), 7.09 / 6.98 (m; 3H, H(13) /H(15)), 4.76(d, J /12.9; 1H, H(21a)), 4.59(d, J /12.9; 1H, H(21b)); dC(d6-DMSO) 155.8(C(2)), 130.9(C(9)), 130.6(C(12) and C(16)),
[8] drawings of [PdCl2(BzSq)] and its intraligand stacking.
M. Kita et al. / Polyhedron 21 (2002) 843 /848
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Table 3 NMR data of [PdCl2(BzSq)] in d6-DMSO
1
Fig. 2. ORTEP [8] drawings of [PdCl2(PheneSq)] and its interligand stacking. Table 2 ˚ ) and bond angles (8) for [PdCl2(BzSq or Selected bond distances (A PheneSq)] [PdCl2(BzSq )] Bond lengths Pd(1) Cl(1) Pd(1) Cl(2) Pd(1) S(1) Pd(1) N(1) S(1) C(8) S(1) C(10) C(10) C(11)
2.315 2.293(1) 2.248(1) 2.046(3) 1.780(4) 1.848(5) 1.489(7)
Pd(2) Cl(21) Pd(2) Cl(22) Pd(2) S(2) Pd(2) N(2) S(2) C(28) S(2) C(30) C(30) C(31)
2.311(1) 2.283(1) 2.237(1) 2.036(4) 1.752(7) 1.832(5) 1.489(7)
Bond angles Cl(1) Pd(1) Cl(2) Cl(1) Pd(1) S(1) Cl(1) Pd(1) N(1) Cl(2) Pd(1) S(1) Cl(2) Pd(1) N(1) S(1) Pd(1) N(1) Pd(1) S(1) C(8) Pd(1) S(1) C(10) C(8) S(1) C(10) S(1) C(10) C(11)
91.07(4) 177.45(5) 95.65(9) 87.18(4) 172.74(9) 86.01(9) 99.1(1) 104.5(2) 100.3(2) 115.3(3)
Cl(21) Pd(2) Cl(22) Cl(21) Pd(2) S(2) Cl(21) Pd(2) N(2) Cl(22) Pd(2) S(2) Cl(22) Pd(2) N(2) S(2) Pd(2) N(2) Pd(2) S(2) C(28) Pd(2) S(2) C(30) C(28) S(2) C(30) S(2) C(30) C(31)
91.28(5) 177.63(5) 95.6(1) 86.69(5) 173.1(1) 86.5(1) 99.0(2) 107.9(2) 101.6(2) 115.3(3)
[PdCl2(pheneSq )] Bond lengths Pd(1) Cl(1) Pd(1) Cl(2) Pd(1) S(1) Pd(1) N(1) S(1) C(8) S(1) C(10) C(10) C(20) C(20) C(11)
2.315(1) 2.287(1) 2.2530(9) 2.036(3) 1.775(4) 1.828(4) 1.507(6) 1.519(2)
Bond angles Cl(1) Pd(1) Cl(2) Cl(1) Pd(1) S(1) Cl(1) Pd(1) N(1) Cl(2) Pd(1) S(1) Cl(2) Pd(1) N(1) S(1) Pd(1) N(1) Pd(1) S(1) C(8) Pd(1) S(1) C(10) C(8) S(1) C(10) S(1) C(10) C(20) C(10) C(20) C(11)
91.60(4) 174.96(4) 94.52(8) 87.96(4) 172.42(8) 86.33(8) 98.9(1) 106.7(1) 102.4(2) 113.5(2) 111.4(3)
13
H NMR
C NMR
Position
d (J /Hz)
Position
d
2 4 7 5 6 3 12,16 13,14,15 21a 21b
9.42(d, J2 3 5.2; 1H) 8.74(d, J3 4 8.2; 1H) 8.32(d, J6 7 7.4; 1H) 8.27(d, J5 6 8.0; 1H) 7.92(t, J5 6 8.0, J6 7 7.4; 1H) 7.74(t, J2 3 5.2, J3 4 8.2; 1H) 7.27(t, J12 13 6.1; 2H) 7.08 /7.00(m; 3H) 4.69(d, J 12.9; 1H) 4.51(d, J 12.9; 1H)
2 10 4 7 11 5 9 12,16 6 14 13,15 8 3 21
153.6 150.5 1470.7 136.9 133.4 131.6 130.2 130.1 128.6 128.4 127.9 126.1 123.2 47.2
129.3(C(6)), 129.0(C(14)), 128.5(C(13) and C(15)), 127.9(C(8)), 124.1(C(3)), 48.3(C(21)). 3.2. [PdX2(PheneSq)](X /Cl and Br) To a solution of Na2[PdCl4] ×/H2O (0.24 g, 0.8 mmol) in 50 cm3 of ethanol was added a solution of PheneSq (0.21 g, 0.8 mmol) in 50 cm3 of ethanol. After stirring at r.t., the resulting orange precipitate was filtered and recrystallized from CH2Cl2. Yield: 0.30 g (85%). Found: C, 40.88; H, 3.19; N, 2.70%. Calc. for [PdCl2(PheneSq)] /C17H15Cl2PdNS: C, 40.97; H, 3.25; N, 2.65%. Its NMR data is shown in Table 4. The corresponding dibromo complex was prepared from K2[PdBr4] in a similar way. Yield: 0.38 g (88%). Found: C,36.92; H, 2.77; N, 2.38%. Calc. for [PdBr2(PheneSq)] /C17H15Br2PdNS: C, 38.41; H, 2.84; N, 2.64%. NMR: dH(J (Hz), d6-DMSO) 10.14 (d, J2 3 / 5.3; 1H, H(2)), 8.48 (d, J3 4 /8.2; 1H, H(4)), 8.04(d, J5 6 /7.5, J6 7 /7.2; 2H, H(7) and H(5)), 7.76(t, J5 6 /7.2, J6 7 /7.2; 1H, H(6)), 7.67(q, J2 3 /5.3, J3 4 /8.2; 1H, H(3)), 7.07(d, J/3.9; 5H, H(12)/ H(16)), 3.83(d, J/11.9; 1H, H(22)), 3.58(s; 2H, H(22)), 3.01(d, J/11.9; 1H, H(21b)); dC(d6-DMSO) 156.9(C(2)), 150.4(C(10)),140.4(C(4)), 137.5(C(7)), 135.7(C(11)), 131.7(C(5)), 130.2(C(8)), 129.2(C(6)),
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129.1(C(12) and C(16)), 128.8(C(13) and C(15)), 127.3(C(14)), 124.2(C(3)), 45.4(C(21)), 36.5(C(22)).
4. Crystallography Single crystals of [PdCl2(BzSq)] (0.25/0.20 /0.12 mm) and [PdCl2(PheneSq)] (0.40 /0.25 /0.25 mm) were fixed on the end of a glass fiber with epoxy resin. They were mounted on a Rigaku AFC-7R diffractometer and the diffraction data were collected at 298 K with graphite-monochromated Mo Ka radiation (l/ ˚ ) using v /2u scan mode. Cell dimensions 0.71069 A were determined by least-squares refinement of the angular positions of 25 independent reflections in the range 28 B/2u B/398 for each sample. Crystallographic data and experimental details are listed in Table 1. The position of the palladium was determined by direct methods (SHELXS-86 [6]) for each complex and the remaining non-hydrogen atoms were located by subsequent Fourier syntheses. The structure was refined on F
by full-matrix least-square techniques with anisotropic thermal parameters for non-hydrogen atoms. Hydrogen atoms were located at positions determined by Fourierdifference syntheses or by calculations. All calculations were carried out with the TEXAN [7] software.
5. Measurement UV /Vis absorption spectra were recorded on an Hitachi U-3400 spectrophotometer, 1H and 13C NMR spectra with a Bruker ARX300 spectrometer. X-Ray crystal analysis was made at the X-ray Diffraction Service of the Department of Chemistry of Osaka University.
6. Results and discussion Neutral complexes [PdX2(L)] (X /Cl or Br-; L / BzSq or PheneSq) were obtained in high yields by the
Fig. 3. Proton NMR spectra of [PdCl2(BzSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric constant of solvent.
M. Kita et al. / Polyhedron 21 (2002) 843 /848 Table 4 NMR data of [PdCl2(pheneSq)] in DMSO
1
13
H NMR
C NMR
Position
d (J /Hz)
Position
d
2 4 7,5 6 3 12,13 14 15,16
9.90(d, J2 3 5.3, J2 4 1.5; 1H) 8.48(d, J3 4 8.3, J2 4 1.5; 1H) 8.03(d, J3 6 7.8, J6 7 7.8; 2H) 7.78(t, J5 6 7.8, J6 7 7.8; 1H) 7.68(q, J2 3 5.3, J3 4 8.3; 1H) 7.11 /7.03(m; 5H) 3.77 /3.46(m; 3H) 3.11 /3.02(m; 1H)
2 10 4 7 11 5 9 6 12,16 8 13,15 14 3 21 22
155.3 150.4 140.6 137.5 135.5 131.7 131.3 129.2 129.1 128.9 128.8 127.4 124.0 45.1 36.3
reaction of [PdX4]2 with sulfide ligands. They were characterized by NMR spectroscopy and elemental analysis. X-ray crystal structures were determined for [PdCl2(BzSq)] and [PdCl2(PheneSq)]. ORTEP [8] drawings of the present complexes are shown in Figs. 1 and 2. Selected bond distances and angles are listed in Table 2. Though there are two similar but independent molecules in [PdCl2(BzSq)], we describe only the structure of Pd(1) hereafter. The BzSq ligand coordinates bidentately through the N,S donors. The Pd /Cl bond distance trans to the ˚ , which is sulfur in [PdCl2(BzSq-N ,S )] is 2.315(1) A ˚ than the Pd /Cl one trans to imine. longer by 0.022(1) A ˚] A similar lengthening of the Pd /Cl bond [0.028(1) A was also observed in [PdCl2(PheneSq-N ,S )]. This bond weakening is known as trans influence [9]. The ligand bite angles [BzSq /86.01(9)8 and PheneSq/86.33(8)8] are normal and typical values. A remarkable feature is the presence of an intraligand stacking interaction between the phenyl group and the quinolyl of BzSq (see Fig. 1(a) (left)). The angle between the phenyl plane and the quinolyl is 46.68. The top view indicates clearly the superimposition between the phenyl group and the quinolyl (Fig. 1(b) (right)). The C(8) /S /C(10) angle of 100.3(2)8 is considerably less than a tetrahedral angle of
847
109.58, which is reasonably ascribed to the intraligand stacking interaction of BzSq. The dihedral angle C(8) / S /C(10) /C(11) is 43.9(4)8. The distance between C(11) and C(9) is 3.60(1) A˚, which is the standard value for a p /p distance. This stacking conformation generates the repulsive interactions of Pd /Cl(2)/ /H /C(10) 3.41(2) A˚ and Pd/ /H/C(12) 2.99(2) A˚ [11]. Interligand stacking interactions between a phenyl group and another ligand (for example, bpy) in a given complex have been often reported [2 /5] but intraligand stacking in the same ligand described here seems to be quite rare. There is no intermolecular stacking interaction between aromatic rings in the present complex. On the other hand, [PdCl2(PheneSq-N ,S )] does not show such an intraligand stacking mode (Fig. 2(a) (left)). In general, a long alkyl chain is apt to adopt an anti conformation, that is, trans conformation, due to the repulsion between adjacent methylene protons. The C(8)-S-C(10) /C(11) dihedral angle is 56.3(4)8 and the S /C(10) /C(20)/C(11) one is 173.4(3)8. The S /CH2 / CH2 /C sequence takes an anti conformation, so that the phenyl group becomes apart from the quinolyl. This is the reason why the PheneSq complex does not have an intraligand stacking mode. Instead there is an intermolecular stacking interaction between two quinolyl groups of adjacent molecules as shown in Fig. 2(b) (right). The distance between the quinolyl planes 3.40(1) ˚ is considerably shorter than the standard value (3.60 A ˚ ) for a p /p distance. Since the crystallographic A inversion is located at the center of the intermolecular quinolyl stacking, the angle between two quinolyl planes becomes 08. The assignments of 1H and 13C NMR signals were carried out by proton homo-decoupling, 1H-detected multiple quantum coherence (HMQC), and 1H-detected multiple bondquantum coherence (HMBC) spectra. The results are listed in Tables 3 and 4. In the 1H NMR spectrum of [PdCl2(BzSq-N ,S )] an interesting splitting was observed: the phenyl proton signals are split into two groups, the group of H(12) and H(16) (d 7.21) and one of H(13), H(14) and H(15) (d 7.09 /6.98), in d6-Me2SO as shown in Fig. 3. The free BzSq in d6-Me2SO shows the phenyl protons at d7.49 (H(12) and H(16)), d 7.34 (H(13) and H(15)), and d 7.29 (H(14)). The changes of chemical shifts on complexation can be related to the ring current effect [10] of pelectrons of the quinolyl group by the aromatic intraligand interaction in d6-Me2SO. Similar changes were observed in CD3OD (7.02 and 6.84) (Fig. 3). On the other hand, the signals of H(13), H(14), H(15) appear at relatively low magnetic field and the chemical shift separations are negligible in CD2Cl2 (d 7.2) or CDCl3 (d 7.2) with low dielectric constants. This result suggests that the aromatic intraligand interaction is recognized in high dielectric solvents and does not occur in low dielectric solvents.
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Fig. 4. Proton NMR spectra of [PdCl2(PheneSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric constant of solvent.
Similar 1H NMR measurements were carried out for [PdCl2(pheneSq-N ,S )]. However, this complex did not show any splitting of the phenyl proton signals as shown in Fig. 4. Thus, the aromatic intraligand interaction could not be observed in the crystal and in solvents. Each dibromo complex [PdBr2(BzSq)] or [PdBr2(PheneSq)] showed the same results as the corresponding dichloro complex. Hence we conclude that [PdBr2(BzSq)] also has a similar noble intraligand stacking interaction as [PdCl2(BzSq)] does in solid and in solvents with high dielectric constants.
7. Supplementary material Crystallographic data have been deposited with the CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: /44-1223-366033; e-mail: [email protected] or www: http://www.ccdc.cam.ac.uk) and are available on request quoting the deposition numbers 169087 for [PdCl2(BzSq)] and 169088 for [PdCl2(pheneSq)].
References [1] (a) C.A. Hunter, Chem. Soc. Rev. (1994), 101, and references therein.; (b) M. Mishio, M. Hirota, Y. Umezawa, The CH /p Interaction, Wiley-VCH, 1998; (c) A. Magistrato, M. Merlin, O.S. Pregosin, U. Rothlisberger, Organometallics 19 (2000) 3591. [2] M. Kita, K. Kashiwabara, J. Fujita, Bull. Chem. Soc. Jpn. 61 (1988) 3187. [3] H. Masuda, T. Sugimori, A. Odani, O. Yamauchi, Inorg. Chim. Acta 180 (1991) 73. [4] T. Sugimori, K. Shibakawa, H. Masuda, A. Odani, O. Yamauchi, Inorg. Chem. 32 (1993) 4951. [5] O. Yamauchi, A. Odani, H. Masuda, Inorg. Chim. Acta 198 /200 (1992) 749. [6] G.M. Sheldrick, SHELXS-86, Program for Crystal Structure Determination, University of Go¨ttingen, 1986. [7] TEXSAN, Crystal Structure Analysis Package, Molecular Structure Corporation, 1985 and 1992. [8] C.K. Johnson, ORTEP-II. Report ORNL-5138, Oak Ridge National Laboratory, Oak Ridge, TN, 1976. [9] M. Kita, K. Kashiwabara, Polyhedron 16 (1997) 2771. [10] A. Odani, S. Deguchi, O. Yamauchi, Inorg. Chem. 25 (1986) 62. ˚ are absent in [11] Such repulsive interactions within 3.60 A [PdCl2(pheneSq)].