cyano) substituted zinc(II)-tetraphenylporphyrins

Inorganica Chimica Acta 372 (2011) 417–424

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Synthesis and crystal structures of five-coordinated b-pyrrole tetra(phenyl/cyano) substituted zinc(II)-tetraphenylporphyrins P. Bhyrappa ⇑, K. Karunanithi Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India

a r t i c l e

i n f o

Article history: Available online 27 February 2011 Dedicated to Prof. S.S. Krishnamurthy Keywords: Octaphenylporphyrin Zinc(II)-porphyrins X-ray crystal structures Nonplanar porphyrins Tetracyanotetraphenylporphyrin

a b s t r a c t Crystal structures of a series of 2,3,5,10,12,13,15,20-octaphenylporphinato zinc(II) complexes with varying axial ligands have been examined to elucidate the role of fifth ligand on the stereochemistry of the porphyrin macrocycle. The nonplanarity of the macrocycle varies in the order, ZnOPP < ZnOPP(pyridine) < ZnOPP(H2O). The electron deficient porphyrin complex of five-coordinated Zn(II), ZnTPP(CN)4(CH3OH) showed enhanced nonplanarity of the macrocycle and it is less than that of ZnOPP(H2O)TCE complex. Normal coordinate structure decomposition analysis of the out-of-plane displacement of the porphyrin ring in these structures revealed negligible wave distortion in planar four-coordinated ZnOPP and saddle, ruffled and domed distortions in other five-coordinated Zn(II)-porphyrins. The pronounced distortion of the macrocyclic ring in these structures is possibly due to the axial ligand, solvate and/or intermolecular interactions compared to steric crowding of the peripheral substituents. Ó 2011 Elsevier B.V. All rights reserved.

1. Introduction Substituted porphyrins and metalloporphyrins are of growing importance owing to their use as model compounds of tetrapyrrole pigments of nature [1]. The introduction of suitable substituents at the periphery of the porphyrin macrocycle alters the physicochemical properties, which are potentially useful for material applications [2]. Perhalogenated high-valent metalloporphyrins have been employed as robust catalysts for the oxidative transformation of organic substrates in presence of strong oxygen donors [3–7]. Furthermore, these halogenated porphyrins showed unique physico-chemical properties [8]. The increase in steric crowding of the substituents at the periphery of the macrocycle cause dramatic changes in distortion of the porphyrin ring and serve as useful model compounds for nonplanar tetrapyrrole pigments of nature [9–10]. Stereochemical properties of the porphyrin macrocycle largely depend on the peripheral substituents, core metal ion, axial ligands, intermolecular interactions and crystal packing forces [11–12]. ZnTPP structures with variety of lattice guest molecules have been reported in the literature [13,14]. Further, ZnTPP and partially b-substituted-ZnTPP are known to form five [15–17] and six coordinate complexes [18–20] in the solid state. The six coordinate Zn(II)-porphyrins exhibited near planar geometry of the porphyrin ring. Crystal structures of numerous substituted porphyrins and metalloporphyrins have been reported in the literature [21]. It is ⇑ Corresponding author. E-mail address: [email protected] (P. Bhyrappa). 0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2011.02.057

known that the introduction of functional groups (Br [22], CH3 [23] and phenyl [24]) at the antipodal b-pyrrole positions of the porphyrin showed expansion of the core along the substituted pyrrole direction in H2TPP(R)4 relative to unsubstituted pyrrole direction and hence they exhibited near planarity of the macrocycle. The reported crystal structures of MOPP (M = Co(II), Cu(II)) complexes [25] revealed planar conformation of the porphyrin ring, which is similar to the parent H2OPP structure. Interestingly, the five-coordinated ZnTPP(R)4 (R = CH3, Br) featured enhanced nonplanar distortion of the porphyrin ring [26,27]. To probe the effect of axial ligand on the stereochemistry of the macrocycle, the crystal structures of a new family of four- and five-coordinated ZnOPP complexes have been examined (Fig. 1). Further, the crystal structure of an electron-deficient porphyrin complex, ZnTPP(CN)4(CH3OH) was also determined. The five-coordinated Zn(II)-porphyrin structures revealed dramatic variation in stereochemistry relative to nearly the planar four-coordinated ZnOPP complex. Normal-coordinate structure decomposition analysis of the out-of-plane displacement of the 24-atom core in these Zn(II)-porphyrins showed interesting distortion modes.

2. Experimental section 2.1. Materials and instrumentation 2,3,12,13-Tetra(cyano/phenyl)-5,10,15,20-tetraphenylporphyrin and their zinc(II) complex were prepared using reported methods [28,29]. The synthesised Zn(II)-porphyrins were characterised

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R

R

(MALDI-TOF) Voyager DE-PRO model mass spectrometer using

a-cyano-4-hydroxycinnamic acid as the matrix. Crystals of four coordinated ZnOPP, 1 complex were grown by diffusing n-hexane vapour to the saturated solution of the porphyrin in 1,1,2,2-tetrachloroethane, TCE. Similarly, ZnOPP(Pyridine), 2 crystals were obtained by diffusion of hexane to the porphyrin in 1,2-dichloroethane containing few drops of pyridine over a period of five-days. ZnOPP(H2O)TCE, 3 crystals were obtained by diffusing vapours of methanol to the ZnOPP in TCE. Crystals of five-coordinated and methanol/H2O solvated ZnTPP(CN)4(CH3OH)(CH3OH) (H2O)1.5, 4 were obtained by diffusing methanol to the ZnTPP(CN)4 in CHCl3 over a period of week. All the crystallisations were carried out at room temperature. Single-crystal X-ray structure data of the Zn(II)-porphyrins were gathered on a Bruker AXS Kappa Apex II CCD diffractometer with graphite monochromated Mo Ka radiation equipped with liquid nitrogen cryostat. The crystals were coated with inert oil, mounted on a glass capillary using quick fix glue, and transferred to the cold nitrogen gas stream of the diffractometer and crystal data were collected at 173 K. The reflections with I > 2r(I) were employed for structure solution and refinement. The SIR92 [30] (WINGX32) programme was used for solving the structure by direct methods. Successive Fourier synthesis was employed to locate all of the non-hydrogen atoms of the structures, after full-matrix least squares refinement on |F|2 using the SHELXL97 [31] software. Hydrogen atoms of the porphyrin structures were geometrically relocated at chemically meaningful positions and given riding model refinement. Hydrogen atoms in water/methanol lattice solvates could not be fixed reliably in structures 3 and 4. Intermolecular short contacts were calculated from PLATON [32] and molecular packing motifs were drawn using MERCURY 2.2 software [33]. ORTEP diagrams were generated using ORTEP3 for windows programme [34].

N N

Zn

N

N

R

R

R = Phenyl; ZnOPP R = CN, ZnTPP(CN)4 Fig. 1. Chemical structures of Zn(II)-porphyrins.

by electronic absorption, 1H NMR and mass spectroscopic techniques. ZnOPP: UV–Vis spectrum in CH2Cl2: kmax, nm (log e): 431 (5.55), 558 (4.36), 601 (sh). 1H NMR in CDCl3: d, ppm, 8.51 (s, 4H, b-pyrrole-H), 7.77 (d, 8H, meso-o-phenyl-H), 7.13 (t, 4H, mesop-phenyl-H), 7.14 (t, 8H, meso-m-phenyl-H), 6.98 (d, 8H, b-pyrrole-o-phenyl-H), 6.86 (m, 12H, b-pyrrole-m & p-phenyl-H). MALDI mass spectrum (m/z): 982 (Calcd., 982.5). ZnTPP(CN)4: UV–Vis spectrum in CH2Cl2: kmax, nm (log e): 442 (5.36), 454 (5.42), 656 (4.68), 672 (sh). 1H NMR in CDCl3: d, ppm, 8.79 (s, 4H, b-pyrroleH), 8.07 (d, 8H, meso-o-phenyl-H), 7.80 (t, 8H, meso-m-phenyl-H), 7.95 (t, 4H, meso-p-phenyl-H). MALDI mass spectrum (m/z): 777.9 (Calcd., 778.15). All the solvents employed in this work were of analytical grade and distilled prior to use. Optical absorption spectra of Zn(II)-porphyrins were carried out on a computer interfaced JASCO V-550 model UV–Vis spectrophotometer using a pair of quartz cells of 1 cm path length in CH2Cl2 at 298 K. 1H NMR spectra of porphyrins were recorded on a Bruker Avance 400 MHz FT-NMR spectrometer in CDCl3, using tetramethylsilane as the internal reference. Mass spectra of Zn(II)-porphyrins were measured on a matrix assisted laser desorption time-of-flight

3. Results and discussion Synthesised ZnOPP and ZnTPP(CN)4 complexes were characterised by electronic absorption, 1H NMR and mass spectroscopic methods. The observed spectroscopic data of these compounds are consistent with the reported values. Crystallographic data of the four and five-coordinated ZnOPP complexes are listed in

Table 1 Crystallographic data of Zn(II)-porphyrin complexes.

Empirical formula Formula weight Colour Crystal system Space group a (Å) b (Å) c (Å) a (°) b (°) c (°) v (Å3) Z Dcalc (g cm3) Radiation (Å) T (K) Total/unique/observed reflections R1a wR2b Goodness-of-fit on F2 (GOF) a b

P P R1 = ||Fo|  |Fc||/ |Fo|; Io > 2r(Io). P P 2 wR2 = [ w(F o  F 2c )2/ w(F 2o )2]1/2.

1

2

3

4

C68H44N4Zn 982.44 brown monoclinic P21/c 7.4997(2) 13.2205(3) 24.4885(6) 90 93.2890(10) 90 2424.03(10) 2 1.346 0.71073 173(2) 14314/4238/3700 0.0298 0.0848 1.223

C73H49N5Zn 1061.54 pink monoclinic P21/c 18.7785(16) 12.3413(11) 24.6545(19) 90.00 108.758(3) 90.00 5410.2(8) 4 1.303 0.71073 173(2) 57938/9368/4920 0.0759 0.1859 1.018

C70H48N4Cl4OZn 1168.29 brown triclinic  P1 10.0144(3) 12.2766(4) 23.1963(7) 99.4170(10) 97.3940(10) 100.9530(10) 2724.29(15) 2 1.424 0.71073 173(2) 31351/9478/6607 0.0470 0.0975 1.026

C50H35N8O3.5Zn 869.23 pink triclinic  P1 11.8282(12) 13.7176(12) 14.2517(13) 111.396(3) 90.125(4) 106.103(3) 2054.7(3) 2 1.405 0.71073 173(2) 21578/6970/5658 0.0664 0.1734 1.059

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Table 1. The four and five-coordinated ZnOPP structures will be discussed first followed by CH3OH/H2O solvated ZnTPP(CN)4 (CH3OH) complex, 4. ORTEP diagrams of the ZnOPP complexes, 1–3 are shown in Fig. 2. The selected bond lengths, angles and geometrical parameters of the Zn(II)-porphyrins are listed in Table 2. The bond lengths of the porphyrin ring are comparable along the substituted and unsubstituted pyrrole directions in both four and five-coordinated ZnOPP complexes (2,3). The values of mean Cb–Cb bond distances in 1 (1.347(3) Å, 1.368(3) Å) and 3 (1.344(4) Å, 1.364(4) Å) complexes are higher in unsubstituted pyrroles than in substituted ones. However, complex 2 showed similar mean Cb–Cb bond distances along both the transannular pyrroles. The values of Zn–Na and Zn–N bond distances (Table 2)

C15

(a) a)

C2

C4

C1

C14

C11

N1

C12

N2

C8 C9 C23 C10 C24 C30 C31

C23 C25 C2 C22 C26 C66 C1 C21 C67 C68 C20 C65 N1 C63 C19 C64 C69 C18 C17 N4 N5 C58 C57 C16 N3 C59 C62 C15 C61 C51 C14 C60 C52 C56 C13 C53 C55 C54

(c)

C66 C67

C29 C3

N1 -0.025

C19 N2i

C3

-0.014 -0.008 -0.001 -0.009

C25 C26

0.030

N1i

C33 C32 0.106

0.132

C30

0.011

-0.002 -0.085 -0.026 0.052

0.009 N1 0.061

0.026 0.015 0.024

N4 -0.122

0.300 N2 Zn 0.004

0.073

0.004 N3 -0.056 -0.002

-0.011 0.096

0.118

-0.008 -0.026

0.033

C48

C25 C24 C2

0.022

0.019 N2 Zn -0.028

C27

C31 C32 C35 C4 C27 C34 C36 C5 C33 C70 C37 C6 C71 C38 C7 N2 C8 C40 C9 C41 C73C72 C39 C10 C44 C45 C11 C43 C42 C46 C12 C50 C47 C49

0.003

-0.014

C28

C65 C64

C28

C34

C29

C24

C18

C7

Zn1

(b)

C21 C20

C22 C5 C17 C6

0.025

0.001

C13

C16

C3

indicate that the b-phenyl substituted pyrroles have longer bonds than the unsubstituted ones suggesting the greater influence of steric crowding and axial ligand than electronic factors [11]. This is also reflected from greater (NN)a when compared to NN distance (Table 2). As anticipated, the axial ligand displaces the Zn(II) ion towards one face of the porphyrin ring resulting in increased Zn–N and Zn–Na bond distances in the equatorial plane in contrast to the reported four-coordinated structure, 1 [12]. The (N–Zn– N)opp and (N–Zn–N)adj angles showed nearly square planar geometry around the Zn(II) centre in four-coordinated 1 and distorted square pyramidal geometry for the five-coordinated 2 and 3 complexes. Fig. 2 shows the deviation of the porphyrin ring atoms from the 24-atom core. The metal ion is almost in the mean porphyrin

0.484 0.524

C26

C23 C68 C22 C21 C1 C4 C63 C60 C61 C5 C32 C31 C30 C62 C20 N1 C29 C19 C59 C6 O1 C58 C57 C27 C28 N4 C7 C18 N2 Zn1 C8 C17 C33 C52 C51 C16 C9 C34 C15 N3 C10 C38 C56 C53 C46 C55 C35 C37 C11 C14 C36 C39 C40 C45 C54 C47 C13 C12 C41 C50 C44 C48 C49 C43 C42

-0.083

0.207

-0.286 -0.838 N4 0.061

-0.740

0.281 N1 0.152

-0.140 0.173 0.326 0.533

0.110

0.444 N2 Zn 0.005

-0.162 -0.680 -0.770 -0.278

0.158 -0.085 N3 0.170 0.424

Fig. 2. Left shows the ORTEP diagram of 1 (a), 2 (b) and 3 (c) complexes. Hydrogens and solvates are not shown for clarity. Thermal ellipsoids at 30% probability level. The rightside shows the mean plane displacement of the macrocycle in Å (esd’s 0.004 Å).

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Table 2 Mean bond lengths, angles and geometrical parameters for Zn(II)-porphyrin structures.

R

R Cb

Cm

Ca

Cb Ca N Cb Ca

Cb Na

Ca R = Ph, ZnOPP, 1

M

N

a b c

R = Ph, ZnOPP(H2O)•TCE, 3 R = CN, ZnTPP(CN)4(CH3OH)•CH3OH•(H2O)1.5, 4

Na

R

R = Ph, ZnOPP(Py), 2

R

1

2

3

4

Distance (Å) Zn–N Zn–Na Ca–N Ca–Cb Cb–Cb Ca–Cm

1.984(3) 2.109(2) 1.380(2) 1.446(2) 1.358(3) 1.405(2)

2.007(2) 2.130(2) 1.376(6) 1.448(8) 1.351(8) 1.403(8)

2.031(2) 2.098(2) 1.373(4) 1.447(4) 1.354(4) 1.405(4)

2.033(4) 2.088(4) 1.368(6) 1.441(7) 1.355(7) 1.404(7)

Angle (°) (N–Zn–N)adj (N–Zn–N)opp Zn–N–Ca Ca–N–Ca Ca–Cm–Ca N–Ca–Cm Cb–Ca–Cm Ca–Cb–CR N–Ca–Cm–Ca Ca–N–Ca–Cb

90.2(2) 180.0(4) 126.6(1) 106.6(2) 125.4(2) 125.6(2) 124.8(2) 130.4(2) 1.2(3) 0.8(2)

89.1(1) 165.7(1) 126.4(3) 106.9(2) 125.8(5) 125.5(5) 125.2(5) 129.7(5) 1.3(6) 1.3(3)

88.4(1) 160.5(1) 125.8(2) 106.7(2) 124.7(3) 124.6(3) 125.9(3) 127.6(3) 10.6(5) 4.5(3)

89.3(2) 166.7(2) 125.2(3) 107.5(4) 124.6(4) 125.5(4) 125.5(4) 130.5(4) 9.6(8) 3.4(5)

Geometrical parameters (Å) DZnb N...N (N. . .N)a r.m.s.

±0.019(2) 3.969 4.218 0.018(2)

±0.300(2) 3.977 4.232 0.086(5)

±0.444(2) 4.019 4.115 0.402(3)

±0.194(2) 4.027 4.156 0.325(4)

Dihedral angle (°)c Meso-Ph b-pyrrole-Ph Pyrrole

73.2(5) 69.8(5) 0.8(2)

79.5(2) 78.3(2) 3.2(3)

57.6(1) 64.7(1) 15.8(2)

57.8(2) – 14.2(2)

b-substituted pyrrole nitrogens. Displacement of Zn(II) ion from the porphyrin mean plane. Relative to porphyrin mean plane.

plane with the minimum deviation of 0.019(2) Å in 1 and higher in the other five-coordinated complexes (2, 3). As anticipated, the average Zn–N bond distance increases from four to five-coordinated ZnOPP and follows the order: 1 < 2  3. The observed mean Zn–Nporhyrin distances are in the range of 2.047–2.069 Å and are comparable to the reported range of values (2.044–2.115 Å) for the five and four coordinated Zn(II)-porphyrins [13–17,22]. The mean plane deviation of the core atoms shows significant distortion of 3 in contrast to 1 and 2. Axial bond distance (O–Zn = 2.144(2) Å) in 3 is shorter than the Zn–Npy = 2.239(8) Å) observed in 2. Similar behaviour was observed in the reported five-coordinated ZnOPP(4-aminopyridine) complex [35]. The stereochemistry of the macrocycle in four and five-coordinated ZnOPP complexes are shown in Fig. 3. Complexes 1 and 2 exhibited minimal displacement of the core atoms. This is reflected from the side-view of the porphyrin macrocycle and rootmean-square (r.m.s.) deviation of the 24-atoms core which is the average deviation of the core atom from the least squares plane (Table 2) and linear displacement diagram of the porphyrin ring atoms is shown in Fig. 3. Amongst the Zn(II)-porphyrins examined in this study, 3 shows considerable nonplanarity of the macrocyclic

ring and trend in nonplanarity of the porphyrin ring in these structures is as follows: 1 < 2 < 3. This is reflected from an increase in Cb–Ca–Cm and concomitant decrease in N–Ca–Cm and Zn–N–Ca angles. An average of about one degree increase in these angles was observed in nonplanar ring of 3 relative to planar 1 (Table 2). Moreover, the N–Ca–Cm–Ca and Ca–N–Ca–Cb torsion angles and mean plane displacement of core atoms (Fig. 2) are significantly higher in nonplanar 3 relative to nearly planar 1 or 2 (Table 2). The increase in distortion of the macrocycle is also revealed from the decrease in dihedral angles for the (b-pyrrole-Ph and meso-Ph) relative to nearly planar 1. A comparison of 3 with the 4 was made to elucidate the influence of b-pyrrole cyano versus phenyl groups on the stereochemistry of the macrocycle. Crystal structure of ZnTPP(CN)4 shows coordination of methanol along with an additional methanol and 1.5 H2O molecules as lattice solvates. The ORTEP diagram of the solvated 4 is shown in Fig. 4. Zn(II) centre is located in a distorted square pyramidal geometry and in the equatorial plane, the Zn–Na distance is longer than Zn–N bond distance (Table 2). This is perhaps due to the depleted electron density on the pyrrolic nitrogen induced by the electron withdrawing cyano groups.

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rms = 0.028(2)

0.5 Displacement (Å)

(a)

0.7 0.3

N3

0.1 -0.1

N1

N4

N2

-0.3 -0.5 -0.7 -0.9 0.7

(b) (b)

rms = 0.090(5)

Displacement (Å)

0.5 0.3 0.1 -0.1

N1

N2

N3

-0.3

N4

-0.5 -0.7 -0.9

(c)

rms = 0.402(3)

Displacement (Å)

0.7 0.5 0.3 0.1

N1

N2

N3

N4

-0.1 -0.3 -0.5 -0.7 -0.9

Fig. 3. Left side shows the ORTEP diagrams with side views of the (a) 1, (b), 2 and (c), 3. The lattice solvates and hydrogens are not shown for clarity. Thermal ellipsoids shown at 30% probability level. The right side shows the linear displacement of 24-atom core.

The Zn(II) ion is displaced above the mean plane by 0.194(3) Å and its fifth methanol ligand has Zn–O bond distance of 2.125(4) Å indicating fairly stronger coordinate bond, it is similar to that observed in 3 and in the variety of other reported fivecoordinated Zn(II)-porphyrins [12]. In case of ZnTPP(H2O) complex, Zn(II) ion is displaced by 0.20 Å from the four nitrogen mean plane with Zn-O distance of 2.20(6) Å [16]. Similar Zn–O (2.226(5) Å) bond distance was reported for highly nonplanar 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphinato zinc(II) methanol complex [36]. Bond lengths and angles of the 24-atom core in 4 are similar to that of the structure 3. The macrocyclic ring in 3 has severe non-planarity as revealed by increased torsion angles and root-mean-square displacement of the core atoms (Table 2). Further, that is also evidenced from the displacement of the core atoms from the porphyrin ring mean plane. The nonplanarity in the five-coordinated ZnOPP complexes is evidenced from increased N–Ca–Cm–Ca and Ca–N–Ca–Cb torsion angles relative to planar 1. Moreover, distortion of the porphyrin ring in solvated 4 is reflected from decreased dihedral angle of the meso-phenyl groups and enhanced dihedral angle of the pyrrole rings relative to the mean porphyrin plane when compared to planar 1. The extent of intermolecular interactions in 3 suggests that the nonplanarity of the macrocycle is possibly due to fifth coordination, solvate. . .porphyrin and porphyrinporphyrin interactions rather than steric crowding of the peripheral substituents. As reported earlier, crystal structures of MOPP (M = 2H [24], Co(II), Cu(II) [25]) revealed near planarity of the porphyrin macrocycle.

Molecular packing of 1 shows interesting intermolecular interactions. Porphyrin molecules are arranged in an offset fashion resulting in one-dimensional chains along unit cell a axis (Fig. 5). The porphyrins in the chain are held by a pair of symmetry related phenylporphyrin ring, C–Hp (2.76–2.89 Å) interactions. Along the array, the adjacent porphyrin mean planes are separated by 4.629 Å. Each such array is interconnected with the adjacent array via C–Hp (2.80–2.86 Å) short contacts. The mean porphyrin planes from the adjacent array are oriented at an angle of approximately 40° relative to each other. The interconnected one-dimensional chains form corrugated layer-like structure. Crystal structure of 2 is isomorphous with 1. Molecular packing diagram of 2 showed weak intermolecular C–Hp interactions. The structure 2 shows slipped stacked dimers formed by complementary C–Hp (2.74–2.79 Å) short contacts between the axial pyridine and the b-pyrrole phenyl group. In the C–Hp bonded dimers, macrocyclic ring planes are separated by 4.978 Å. Each dimer interacts with the adjacent one via weak C–Hp (2.84 Å) interaction to form one-dimensional chain oriented along unit cell a axis (Fig. S1, supporting information). The bridging of one dimensional chain is induced by a pair of C–Hp (2.79–2.82 Å) contacts. Similarly, in complex, 3 the molecules are arranged in one-dimensional chains and are weakly held by porphyrinporphyrin C–Hp (2.75–2.86 Å) contacts and these one-dimensional chains are held by weak C–Hp (2.82 Å) interactions to form layer-like structure and it is oriented parallel to unit cell ab plane (Fig. 6). The lattice solvate is located in between the porphyrin faces to fill the void space. These layers are interconnected via solvent mediated

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C41

C23 C24

C22

C25

N7

C2

C3

C21

C40

C1 C4 C26 C5 N1 C49 C6 O1 C46 N4 C7 C8 Zn1 N2 C45 C9

N8

C32 C31 C30

C27

C14

C11

C28

C29

C43

C39

N3

C10

C42 C44

C20 C19

C48 C18 C17 C47 C16 N6 C15 C33 C34 C35

C13 C38

C12

N5

C37 C36

(a)

(b) -0.492

-0.496 -0.210 -0.077

-0.192 N1 -0.061

0.123 0.524

0.208

-0.102 N3

0.016

0.170 0.541

0.194 N2 Zn 0.010

N4 -0.027

0.624

-0.004

0.552 0.183

-0.023 -0.232

-0.204 -0.508

-0.517

(c) Fig. 4. ORTEP diagram of complex, 4 showing (a) top view; (b) side-on-view (the hydrogens and solvates are not shown for clarity). (c) Shows the mean plane deviation of the core atoms in Å (esd’s; 0.004 Å). Colour scheme: Zn, pink; N, blue; C, grey and O, red. (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)

porphyrin. . .porphyrin, C–Hp (2.83 Å) and porphyrinTCE, C–HCl (2.94 Å) and TCEporphyrin, C–HN (2.69 Å) contacts to form three dimensional structure. The structure shows filling of void space by the lattice solvate molecules. Molecular packing of 4 may be approximated as a layer structure oriented parallel to ac plane and shows slipped stacked porphyrin. . .porphyrin dimers which are held by C–Hp (2.63– 2.83 Å) facing each other (Fig. S2, supporting information). The mode of packing is comparable to that of complex, 3. The vertical separation between the porphyrin mean planes in the dimer is 3.805 Å. Within the layer, the closest vertical separation between the mean porphyrin planes in the adjacent dimer is at a distance of 5.283 Å. Each dimer interact with the adjacent four dimers via coordinated (CH3OH) solvateporphyrin, O–HN (2.20 Å) and C–HN (2.70 Å) and porphyrinporphyrin, C–Hp (2.85 Å) close contacts. Each layer is interconnected by C–Hp (2.88 Å) and C–HN (2.61 Å) short contacts. These layers stack along the unit cell ‘‘b’’ axis. The lattice solvate CH3OH is partially disordered

and form C–HO (2.68 Å) with phenyl group and also hydrogen bonds with lattice H2O solvate (OO = 2.66 Å). The water molecules in turn hydrogen bonded to each other with the OO separation of 2.53 Å. The close contact distances in these Zn(II)porphyrins indicates weak intermolecular interactions [37,38]. The nonplanar distortion of the macrocycle is caused by intramolecular interactions between the atoms of the axial ligand and the porphyrin ring, intermolecular interactions between the porphyrins, the size of the core metal ion, the coordination requirements of the core metal ion and the crystal packing forces [11]. It was reported earlier, the nonplanar conformation of the fourcoordinated ZnTPP [14] and substituted four coordinated ZnTPP [ZnT(40 -OH Ph)P, ZnT(40 -Cl Ph)P, ZnT(40 -Cl Ph)P [39] and ZnT(4-Br Ph)P [40]] feature slight saddled distortion of the macrocycle and the five-coordinated ZnT(40 -Cl Ph)P with varying axial ligand showed near planarity of the porphyrin ring [41]. The porphyrin ring in four coordinated structure 1 is nearly planar and slightly nonplanar in structure 2 but complexes 3 and 4 feature significant distortion. The distortion of the porphyrin rings in these complexes follow the order 1 < 2 < 4 < 3. The dramatic distortion in the complexes 3 and 4 is perhaps due to intermolecular, axial ligand and crystal packing forces than steric effect of the peripheral phenyl/cyano groups. Normal-coordinate structure decomposition analysis [42,43] for the out-of-plane displacement of the macrocyclic rings in these five-coordinated Zn(II)-porphyrins feature interesting trend in their distortions relative to four-coordinated complex, 1. The outof-plane displacement data based on the minimum basis set is listed in Table 3. The sum and the individual percentage distortions were calculated by neglecting the signs on the individual displacements. The out-of-plane-displacement (Doop) values of the fivecoordinated Zn(II) porphyrins are considerably higher than the four-coordinated complex, 1 and follow the order 1 < 2 < 4 < 3. The complex 1 reveal essentially minimal wave distortion whereas the other 2, 3 and 4 complexes showed sad (B2u) combined with varying degree of ruf (B1u) and dom (A2u) distortions. The extent of displacement of the Zn(II) ion from the mean plane of the porphyrin ring indicates the influence of the fifth-ligand and the lattice solvates. As anticipated, the extent of distortion observed for in-plane displacement is lower than those observed for the out of plane displacement values. The in-plane-displacement (Dip) of the macrocyclic rings in these Zn(II)-porphyrins feature interesting trend. It is known that the nonplanarity of the macrocycle and the nature of the metal ion influence the Dip values [42]. The nearly planar macrocyclic rings in 1 and 2 feature enhanced displacement in Dip values relative to nonplanar macrocycles of 3 and 4. In these structures, the extent of B1g distortion follows the order 1 > 2 > 4 > 3 and an opposite trend was observed in B2g distortion mode. Moreover, the trn(x), trn(y) and A2g distortions are significantly lower in these systems when compared to those of B1g, B2g and A1g distortions. The NSD analysis of Zn(II)-porphyrins indicate the influence of axial ligand on the magnitude of the Dip and Doop values.

4. Conclusions Crystal structures of four Zn(II) porphyrins, 1–4 complexes have been examined by single crystal X-ray analysis. The complex 1 showed planar conformation of the porphyrin ring while the five-coordinated 3 revealed marked nonplanarity when compared to complex, 2. The electron deficient solvated 4 indicated significant distortion of the macrocyclic ring but it is less in contrast to 3. Macrocyclic ring distortion in these structures indicates sad, ruf and dom distortions and extent of nonplanarity follows the order: 1 < 2 < 4 < 3. The macrocycle in four-coordinated ZnOPP is

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Fig. 5. Molecular motifs of complex, 1 showing the two interconnected one-dimensional arrays oriented approximately parallel to the unit cell ‘‘a’’ axis. For clarity, the porphyrins in different array are shown in colours. The dotted red lines indicate the C–Hp inter-porphyrin interactions in the array and between the arrays. Colour scheme: Zn, pink; N, blue; carbon and hydrogen, green or grey. (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 6. Molecular packing motif of the complex, 3. Minor disordered TCE and coordinated H2O are not shown for clarity. View along unit cell approximately ‘‘c’’ axis. Colour scheme: C and H, grey; N, blue; Cl, green and Zn, pink. (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)

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Table 3 Normal-coordinate structure decomposition analysis of Zn(II)-porphyrins. Doop

B2u (sad)

B1u (ruf)

A2u (dom)

Out-of-plane displacements (Å) 1a 0.0320 0.0000 0.0001 2 0.2635 0.1443 0.1257 3 1.9448 1.8743 0.3092 4 1.5962 1.5875 0.0783 Dip

B2g (m-str)

In-plane displacements (Å) 1 0.3678 0.0098 2 0.3784 0.0303 3 0.0710 0.0184 4 0.0632 0.0313 a

0.0000 0.1665 0.4031 0.1312

Eg(x) (wav(x))

Eg(y) (wav(y))

A1u (prop)

Sum

sad/sum (%)

ruf/sum (%)

dom/sum (%)

0.0280 0.0648 0.0409 0.0509

0.0156 0.0186 0.0962 0.0337

0.0008 0.0241 0.0184 0.0259

0.0445 0.5440 2.7421 1.9075

0.00 26.53 68.35 83.22

0.22 23.11 11.27 4.10

0.00 30.61 14.70 6.87

B1g (N-str)

Eu(x) (trn(x))

Eu(y) (trn(y))

A1g (bre)

A2g (rot)

sum

B2g/sum (%)

B1g/sum (%)

A1g/sum (%)

0.2885 0.3029 0.0329 0.0493

0.0006 0.0077 0.0057 0.0142

0.0009 0.0138 0.0165 0.0048

0.2274 0.2239 0.0555 0.0180

0.0138 0.0138 0.0149 0.0053

0.5410 0.5924 0.1439 0.1229

1.81 8.0 12.8 25.5

53.3 51.1 22.9 40.1

42.0 37.8 38.6 14.6

Mainly wav(x) and wav(y) distortions.

planar and the nonplanarity of the other five-coordinated Zn(II)porphyrins suggests the influence of the axial ligand. The intermolecular interactions, lattice solvate, axial ligand and crystal packing forces are more responsible for the stereochemistry of the macrocycle than steric crowding of the peripheral substituents around the porphyrin ring. Acknowledgements This work was financially supported by the research grant from the Department of Science and Technology (DST), Government of India to P.B. We thank Mr. V. Ramkumar for data collection at the single crystal X-rd facility at the Department of Chemistry at IIT Madras. Appendix A. Supplementary material CCDC 789152, 789153, 789154 and 789155 contain the supplementary crystallographic data for complexes 1, 2, 3 and 4, respectively. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif. Molecular packing diagrams of structure 2 and 4 are also available. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ica. 2011.02.057. References [1] K.M. Kadish, K.M. Smith, R. Guilard (Eds.,), The Porphyrin Handbook, vols. 1– 10, Academic Press, San Diego, 2000 (and references cited therein). [2] J.H. Chou, M.E. Kosal, H.S. Nalwa, N.A. Rakow, K.S. Suslick (Ed.), Applications of porphyrins and metalloporphyrins to materials chemistry, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, vol. 6, Academic Press, New York, 2000 (Chapter 41 author). [3] D. Dolphin, T.G. Traylor, L.Y. Xie, Acc. Chem. Res. 30 (1997) 251 (and references therein). [4] R.A. Sheldon, Metalloporphyrins in Catalytic Oxidations, Marcel Dekker, New York, 1994. [5] F. Montanari, L. Casella, Metalloporphyrins in Catalysed Oxidations, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1994. [6] B. Meunier, Chem. Rev. 92 (1992) 1411. [7] P.E. Ellis, J.E. Lyons, Coord. Chem. Rev. 105 (1990) 181. [8] M.O. Senge (Ed.), Highly substituted porphyrins, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, vol. 1, Academic Press, New York, 2000 (Chapter 6 author). [9] J.A. Shelnutt, X.-Z. Song, J.-G. Ma, S.L. Jia, W. Jentzen, C.J. Medforth, Chem. Soc. Rev. 27 (1998) 31 (and references therein).

[10] M. Ravikanth, T.K. Chandrashekar, Struct. Bonding (Berlin) 82 (1995) 107. [11] W.R. Scheidt (Ed.), Systematics of the stereochemistry of porphyrins and metalloporphyrins, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, vol. 3, Academic Press, San Diego, 2000 (Chapter 16 author). [12] W.R. Scheidt, Y.J. Lee, Struct. Bonding (Berlin) 64 (1987) 1. [13] M.P. Byrn, C.J. Curtis, S.I. Khan, P.A. Sawin, R. Tsurumi, C.E. Strouse, J. Am. Chem. Soc. 112 (1990) 1865. [14] M.P. Byrn, C.J. Curtis, I. Goldberg, Y. Hsiou, S. I Khan, P.A. Sawin, S.K. Tendick, C.E. Strouse, J. Am. Chem. Soc. 113 (1993) 9480. [15] M.P. Bym, C.J. Curtis, Y. Hsiou, S.I. Khan, P.A. Sawin, S.K. Tendick, A. Terzis, C.E. Strouse, J. Am. Chem. Soc. 115 (1993) 6549. [16] M.D. Glick, G.H. Cohen, J.L. Hoard, J. Am. Chem. Soc. 89 (1967) 1996. [17] P. Bhyrappa, V. Velkannan, Tetrahedron Lett. 51 (2010) 40. [18] C.K. Schauer, O.P. Anderson, S.S. Eaton, G.R. Eaton, Inorg. Chem. 24 (1985) 4082. [19] P. Bhyrappa, S.R. Wilson, K.S. Suslick, J. Am. Chem. Soc. 119 (1997) 8492. [20] S. DiMagno, V.S.-Y. Lin, M.J. Therien, J. Am. Chem. Soc. 115 (1993) 2513. [21] M.O. Senge (Ed.), Database of crystal structure determination, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin Handbook, vol. 10, Academic Press, San Diego, 2000. [22] J.H. Zou, Z.I. Xu, X.Z. You, Acta Crystallogr., Sect. C 51 (1995) 760. [23] P. Bhyrappa, K. Karunanithi, B. Varghese, Acta Crystllogr., Sect. E 63 (2007) o4755. [24] K.S. Chan, X. Zhou, B.-S. Lou, T.C.W. Mak, J. Chem. Soc., Chem. Commun. (1994) 271. [25] P. Bhyrappa, K. Karunanithi, Inorg. Chem. 49 (2010) 8389. [26] Y. Terazono, B.O. Patrick, D. Dolphin, Inorg. Chem. 41 (2002) 6703. [27] P.K. Kumar, P. Bhyrappa, B. Varghese, Tetrahedron Lett. 44 (2003) 4849. [28] H.J. Callot, Bull. Soc. Chim. Fr. 24 (1974) 1492. [29] P. Bhyrappa, N. Sankur, B. Varghese, Inorg. Chem. 45 (2006) 4136. [30] A.G. Altomare, G. Cascarano, C. Giacovazzo, A. Gualardi, J. Appl. Crystallogr. 26 (1993) 343. [31] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112. [32] A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7. [33] I.J. Bruno, J.C. Cole, P.R. Edgington, M. Kessler, C.F. Macrae, P. McCabe, J. Pearson, J. Taylor, Acta Crystallogr., Sect. B 58 (2002) 389. [34] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565. [35] T. Kojima, T. Nakanishi, T. Honda, R. Harada, M. Shiro, S. Fukuzumi, Eur. J. Inorg. Chem. (2009) 727. [36] K.M. Barkigia, M.D. Berber, J. Fajer, C.J. Medforth, M.W. Renner, K.M. Smith, J. Am. Chem. Soc. 112 (1990) 8851. [37] G.R. Desiraju, Acc. Chem. Res. 35 (2002) 565. [38] G.R. Desiraju, T. Steiner (Eds.), The weak hydrogen bond in structural chemistry and biology, in: IUCr Monographs on Crystallography, vol. 9, Oxford University Press, Oxford, 1999. [39] I. Goldberg, H. Krupitsky, Z. Stein, Y. Hsiou, C.E. Strouse, Supramol. Chem. 4 (1995) 203. [40] P. Dastidar, H. Krupitsky, Z. Stein, I. Goldberg, J. Inclusion Phenom. 24 (1996) 241. [41] H. Krupitsky, Z. Stein, I. Goldberg, J. Inclusion Phenom. 20 (1995) 211. [42] W. Jentzen, J.-M. Ma, J.A. Shelnutt, Biophys. J. 74 (1998) 753. [43] L. Sun, W. Jentzen, J.A. Shelnutt, The Normal Coordinate Structural Decomposition Engine. .