Syntheses and structural diversity of salicylideneaniline derivatives with cobaltadithiolene backbone

Journal of Molecular Structure 1008 (2012) 77–82

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Syntheses and structural diversity of salicylideneaniline derivatives with cobaltadithiolene backbone Mitsushiro Nomura ⇑, Tomoko Nakamura, Yohei Kashimura, Toru Sugiyama, Masatsugu Kajitani ⇑ Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1, Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan

a r t i c l e

i n f o

Article history: Received 20 September 2011 Accepted 18 November 2011 Available online 26 November 2011 Keywords: Cobaltadithiolene Salicylideneaniline Dihedral angle Hydrogen bonding Molecular structure

a b s t r a c t Salicylideneaniline (SA) or benzylideneaniline (BA) derivatives with [CpCo(dithiolene)] backbone, which are formulated as [CpCo(S2C2(H)(R))] (R = 5-chlorosalicylideneaniline (2a), salicylideneaniline (2b), benzylideneaniline (2c) and 3,5-di-t-butylsalicylideneaniline (2d)), were prepared from the aniline precursor [CpCo(S2C2(H)(C6H4-NH2))] (1) and the corresponding aldehydes. 1 and 2a–2d were identified with spectral data and electrochemical redox potentials. 1 and 2a–2c were structurally determined by X-ray diffraction studies. 1 and 2a showed dithiolene-H  X hydrogen bondings (X = N (1), O (2a)), because the dithiolene proton is usually acidic (ca. 9 ppm by 1H NMR). In 2a–2c, the dihedral angles between two benzene rings (h1) in the SA (or BA) moieties were depending on the substituents on these benzene rings. 2a has small h1 angle (7.321°) and the result indicates a short intramolecular OHN hydrogen bonding distance (1.743 Å). In the crystal of 2b (or 2c), there are two (or four) crystallographically independent molecules, and their h1 angles are different by the flexible SA (or BA) unit. The crystal 2b contains a non-planar molecule (h1 = 37.043°) and a relatively planar molecule (h1 = 22.822°) as well. Ó 2011 Elsevier B.V. All rights reserved.

1. Introduction Salicylideneanilines (SA) are quite interesting compounds [1] because they show either photo- or thermochromic behavior depending on the substituents on the benzene rings. The SA derivatives undergo tautomerism by a proton transfer from oxygen (OH) to nitrogen atom [2]. This proton transfer is the origin of their chromic behavior. One other important thing for the chromic behavior is the planarity of the SA unit [3]. An SA derivative with a non-planar configuration, whose dihedral angle between two benzene rings is larger than 25°, is photochromic. On the other hand, we can observe thermochromism of the SA derivative when the dihedral angle is smaller than 25°. Basically we can tune the dihedral angle by introducing various substituents on the benzene rings, and eventually the intramolecular OH  N hydrogen bonding distance can be modified as well. In addition, many researchers have developed the SA derivatives involving transition metal complexes [4,5], organometallic complexes [6] or other lanthanoid and actinoid complexes [7], because we may introduce the structural diversity of SA unit to the metal complexes. Otherwise, the SA itself can be a coordinating ligand as a Schiff base [8]. In the view point of material science, liquid crystalline metal complexes (metallo-

⇑ Corresponding authors. Present address: Condensed Molecular Materials Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan (M. Nomura). Tel.: +81 48 467 9412; fax: +81 48 462 4661. E-mail address: [email protected] (M. Nomura). 0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2011.11.027

mesogen) with an SA backbone and luminescent complexes derived from an SA ligand were reported [8,9]. Recently, Hahn et al. reported the syntheses and structures of some SA-bound metal dithiolene complexes (Chart 1, M = Ti and Ni, dithiolene = S2C2R2 2 ) [10]. The metal dithiolene complexes are widely investigated for their chemistry, solid state physics and optical materials, because of their attractive p-electron systems [11]. The recent report by Hahn motivated us to synthesize the SA-bound [CpCo(dithiolene)] (Cp = g5-cyclopentadienyl) complexes toward probable chromic metal complexes. The series of [CpCo(dithiolene)] complex has been well developed by our research group [12]. Although unfortunately we have not found any chromic behavior with the resulted SA-[CpCo(dithiolene)] complexes, here we report the syntheses, structural diversity, spectral and electrochemical characterizations of the SA-[CpCo(dithiolene)] complexes and the analog compound.

2. Results and discussion 2.1. Preparation and spectroscopy of salicylideneaniline (SA) or benzylideneaniline (BA) derivative [CpCo(dithiolene)] complex with 4-aminophenyl group [CpCo(S2C2(H)(C6H4-NH2))] (1) was prepared by the one-pot reaction of [CpCo(CO)2], elemental sulfur and 4-ethynylaniline in 10% yield, as a conventional procedure [13]. 1 was further reacted with 5-chlorosalicylaldehyde, salicylaldehyde or 3,5-di-t-butyl-2-

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nOH

OH

N

O

N

NH

O

NH

S

S

Ni S

Ti S

2

Chart 1. Early examples of SA-bound metal dithiolene complex.

hydroxybenzaldehyde in the presence of molecular sieves to form the corresponding salicylideneaniline (SA) derivative in 35% (2a), 13% (2b) or 12% (2d) yield (Scheme 1). For a structural comparison, a benzylideneaniline (BA) derivative (2c) was also prepared from benzaldehyde and 1 in 12% yield. 1 and 2a–2d were isolated as darkblue solids and all the products were identified with spectroscopic data. The 1H NMR spectra of 1 and 2a–2d indicated the existences of a dithiolene proton around 9 ppm in deuterated chloroform solutions (Table 1). Such lower magnetic shifts are due to the ring current effect of the aromatic cobaltadithiolene (CoS2C2) ring [14]. Furthermore, 2a–2d showed 1H NMR responses by their N@CH moieties around 8.5–8.7 ppm (Table 1), which are similar to those of typical SA (or BA) derivatives [15]. Normally, typical SA derivatives are pale yellow and the UV-irradiations of them demonstrate color changes to dark. However, the crystal colors of 2a and 2b with UV-irradiations looked unchanged because their crystal colors were originally dark. The UV–vis spectra of 1 and 2a–2d in dichloromethane solutions give electronic absorption by LMCT in the cobaltadithiolene ring (kmax = 602–621 nm), that are basically due to HOMO–LUMO electronic transition. 2a–2d showed blueshift of the LMCT, compared with 1 (621 nm). Moreover, remarkable absorption based on the SA (or BA) moieties [16] in near-UV region (kmax = 361– 375 nm) are observed in 2a–2d (Table 1). UV-irradiations for dichloromethane solutions of the SA derivatives 2a, 2b and 2d were performed by using high-pressure Hg lamp (see Supplementary materials). The initial blue solutions were changed to yellow.

NH2

R3 R1

S Co S

+ H

O

R2

1 R3 R1 N -H2O

S Co S

R2

H 1

2a: R = OH, R2 = Cl, R3 = H 2b: R1 = OH, R2 = H, R3 = H 2c: R1 = H, R2 = H, R3 = H 2d: R1 = OH, R2 = t-Bu, R3 = t-Bu Scheme 1.

However, these photoreactions indicated decompositions of these SA derivatives and unidentified products were formed. Thus, no reversible photochromism was found in solution. One problem may be photochemical instability of the complexes. The redox potentials were obtained by the CV measurements of 1 and 2a– 2d in dichloromethane solutions (Table 1). They showed well-defined reversible reduction waves and irreversible oxidation waves. The former waves are due to the reduction of the central CoIII (LUMO) and the latter waves are based on the dithiolene ligand (HOMO) [17]. The reduction potentials of 2a–2d (E1/ 2 = 1.25 V  1.29 V) are slightly more positive than that of 1 (E1/2 = 1.34 V), but the oxidation potentials of them (Ep = 0.50– 0.55 V) are remarkably more positive than that of 1 (Ep = 0.13 V). These electrochemical data explained that the introduction of SA (or BA) group to 1 decreases the electron density of the dithiolene ligand (HOMO) and eventually we observe blueshift of the LMCT (HOMO–LUMO) absorption in 2a–2d, compared with 1. 2.2. Structural characterizations of aniline, SA and BA derivatives The single crystals of 1 and 2a–2c were obtained. The selected bond lengths, bond angles and dihedral angles are summarized in Table 2. Their crystal data are collected in Table 3. The bond lengths and angles in the cobaltadithiolene rings are totally similar to those of normal [CpCo(dithiolene)] complexes [17]. These molecules have two-legged piano-stool geometries, because their Cp ligands are located in perpendicular with respect to the cobaltadithiolene ring (see h3 dihedral angle). In 2a–2c, the geometrical conformations of their N@CH moieties are all Z forms. In the crystal of 1, there are two crystallographically independent molecules, which are shown as Co1 and Co2 in the unit cell (Fig. 1), but these two molecules have almost similar geometries. The same molecules are interacted through dithiolene-S  H hydrogen bondings with distances of 3.17–3.26 Å. We have previously found the dithiolene-S  H hydrogen bondings in some [CpCo(dithiolene)] complexes with an amide group [18]. In addition, there are some intermolecular dithiolene-H  N hydrogen bondings in 1 with distances of 2.724 and 2.847 Å (Fig. 1). As a previous work, [CpCo(dithiolene)] complex having 2-pyridonyl group exhibited an intermolecular dithiolene-H  O hydrogen bonding with 2.283 Å [19]. These facts suggest that the dithiolene proton could be somewhat acidic. Actually, an aromatic dithiolene proton appears around 9 ppm in 1H NMR spectra (Table 1) whose d value is lower magnetic field than those of typical organic aromatics. In 2a, one molecule is crystallographically independent (Fig. 2). Fig. 3a demonstrates that there are an intramolecular OH  N hydrogen bonding (1.743 Å) at the SA moiety, intermolecular H  Cl (2.965 Å) and dithiolene-H  O hydrogen bondings (2.627 Å). The molecule 2a looks almost planar without the Cp ligand. In fact, the dihedral angle between the cobaltadithiolene and neighbored benzene ring (h2) is 19.196°, and the angle between two benzene rings at the SA moiety (h1) is 7.321° (Table 2). The crystal 2a might be thermochromic because the h1 is smaller than 25° as described in the introduction of this paper. Eventually, we observe intermolecular pp stacking with between the SA moieties (Fig. 3b). There are two stacking layers in the unit cell but these layers are crystallographically identical. In 2b, two molecules are crystallographically independent, which are shown as Co1 and Co2 in Fig. 4. The Co1 molecule interacts with the other Co2 molecule with a Cp  Cp contact (Fig. 5). Recently, one other research group and we reported the unique Cp  Cp interactions in some [CpnM(dithiolene)] complexes (M = Co [20] and Ni, n = 1 [21]; M = W, n = 2 [22]). One remarkable difference of two molecules is the dihedral angle of h1. The Co1 molecule has h1 = 37.043° and the other has the angle of 22.822° (Table 2 and Fig. 4). The crystal 2b might contain both

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M. Nomura et al. / Journal of Molecular Structure 1008 (2012) 77–82 Table 1 1 H NMR, UV–vis spectral data and redox potentials (vs Fc/Fc+). 1

H NMR data/ppm

1 2a 2b 2c 2d

UV–vis data (kmax/nm)

Redox potentials

Dithiolene-H

N@CH

SA or BA

LMCT

E1/2(red)/V

Ep(ox)/V

8.96 9.04 9.05 9.06 9.06

– 8.59 8.66 8.51 8.68

– 375 367 361 373

621 602 603 604 603

1.34 1.25 1.26 1.27 1.29

0.13 0.55 0.51 0.53 0.50

Table 2 Selected bond lengths (Å), bond angles (°) and dihedral angles (°) in cobaltadithiolene ring. 1a

2a

2ba

2ca

Bond length Co1–S1 Co1–S2 S1–C1 S2–C2 C1–C2

2.120(2) 2.101(3) 1.719(8) 1.703(9) 1.350(13)

2.1007(8) 2.1065(9) 1.722(2) 1.700(2) 1.357(4)

2.1056(12) 2.1083(12) 1.726(3) 1.703(4) 1.361(5)

2.1093(15) 2.1034(15) 1.717(4) 1.698(5) 1.354(6)

Bond angles S1–Co1–S2 Co1–S1–C1 Co1–S2–C2 S1–C1–C2 S2–C2–C1

90.83(11) 106.1(2) 105.0(4) 116.6(6) 121.3(8)

90.78(3) 106.62(9) 105.34(11) 116.6(2) 118.5(2)

91.12(4) 106.16(13) 105.07(14) 116.7(2) 119.4(2)

90.61(5) 106.77(17) 105.17(18) 116.1(3) 121.4(3)

Dihedral angles h1b h2b h3b

–c 30.314, 26.903 89.523, 88.426

7.321 19.196 89.775

37.043, 22.822 13.728, 8.909 87.073, 88.153

65.246, 57.241, 13.901, 84.764 25.237, 24.818, 4.526, 1.983 88.522, 84.051, 88.466, 89.994

Hydrogen bonding OH  N (intramolecular) NH  S (intermolecular) Dithiolene-H  X

–c 3.274(2), 3.250(2) 2.724(9), 2.847(8) (X = N)

1.743(2) –d 2.627(2) (X = O)

1.772(4), 1.755(5) –d –d

–c –d –d

a

For bond lengths and angles, data of one of two (or four) independent molecules are shown. h1 is the dihedral angle between two benzene rings in salicylideneaniline (or benzylideneaniline) moiety. h2 is the dihedral angle between cobaltadithiolene and neighbored benzene ring. h3 is the dihedral angle of Cp/cobaltadithiolene. c Not applicable. d Not observed. b

Table 3 Crystallographic data. Compound

1

2a

2b

2c

Formula FW (g mol1) Crystal color Crystal shape Crystal size (mm) Crystal system Space group T (K) a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dcalc (g cm3) l (mm1) Total refls. Unique refls. (Rint) Unique refls. (I > 2r(I)) R1 (I > 2r(I)) wR2 (I > 2r(I)) Goodness-of-fit

C13H12CoNS2 305.30 Darkblue Platelet 0.45  0.13  0.03 Orthorhombic Pna21 (No. 33) 298 16.440(5) 5.8686(18) 25.736(8)

C20H15ClCoNOS2 443.85 Darkblue Block 0.08  0.08  0.05 Monoclinic P21/c (No. 14) 298 8.8302(18) 6.2812(13) 33.272(7)

C20H16CoNOS2 409.41 Darkblue Chip 0.25  0.15  0.06 Triclinic P-1 (No. 2) 298 10.024(3) 12.051(4) 16.070(5) 105.201(3) 105.253(3) 96.369(3) 1773.2(10) 4 1.533 1.211 14,048 7780 (0.023) 5231 0.0410 0.1061 1.029

C20H16CoNS2 393.41 Darkblue Platelet 0.25  0.08  0.05 Monoclinic P21/n (No. 14) 298 12.523(2) 19.293(4) 29.300(6)

94.1886(9) 2483.0(13) 8 1.633 1.692 16,924 5301 (0.060) 3877 0.0594 0.1371 1.042

R1 = R||Fo| – |Fc||/R|Fo|; wR2 = [R(w(F 2o – F 2c )2)/Rw(F 2o )2]1/2.

1840.4(7) 4 1.602 1.314 13,824 4201 (0.030) 3183 0.0411 0.1073 1.023

91.7412(8) 7076(2) 16 1.477 1.201 54,487 16,102 (0.046) 9100 0.0678 0.1444 1.110

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Fig. 4. ORTEP drawings of two crystallographically independent molecules of 2b (Thermal ellipsoids 30% probability level). Side view from the cobaltadithiolene rings.

Fig. 1. Projection view along the b axis of 1.

Fig. 5. Packing diagram showing intermolecular Cp  Cp interaction in 2b.

Fig. 2. ORTEP drawing of 2a. Thermal ellipsoids are drawn at 30% probability level.

photochromic and thermochromic molecules, because the former molecule is non-planar (h1 > 25°) and the latter is more planar (h1 < 25°) at the SA unit. The h1 is normally relating to the intramolecular OHN hydrogen bonding distance; 1.772 Å for Co1 and 1.755 Å for Co2. For a comparison, the complex 2a with small h1 (7.321°) has shorter hydrogen bonding distance as noted above (1.743 Å). In the crystal of the BA derivative 2c, there are four crystallographically independent molecules (Co1–Co4 in Fig. 6). Interestingly, these h1 angles are all different (Co1: 65.246°, Co2: 57.241°, Co3: 13.901°, Co4: 84.764°). We assume that two benzene rings in the BA moiety can be flexible because there is no OH  N hydrogen bonding. Furthermore, 2c also showed the intermolecular Cp  Cp interactions as similar as 2b (Fig. 7).

Fig. 6. ORTEP drawings of four crystallographically independent molecules of 2c. Side view from the cobaltadithiolene rings.

Fig. 3. (a) Projection view along the c axis of 2a with some hydrogen bonding interactions. (b) Packing diagram showing intermolecular pp interactions in 2a.

M. Nomura et al. / Journal of Molecular Structure 1008 (2012) 77–82

81

4.3. Preparations of 2a, 2b, 2c and 2d

Fig. 7. Packing diagram of 2c with Cp  Cp interactions.

3. Conclusion In this work, we obtained some SA derivatives with [CpCo(dithiolene)] backbone. Unfortunately, no photochromic behavior was observed because of probable photochemical instability of this system. To overcome this problem in future, we may introduce some fluorine atoms in these SA derivatives. On the other hand, we found the structural diversity of the SA[CpCo(dithiolene)] derivatives based on the structural flexibility of the SA moieties. Namely, there may be coexistence of photochromism (h1 > 25°) and thermochromism (h1 < 25°) in the same crystal (e.g. 2b).

4. Experimental section 4.1. Materials and instrumentation All reactions were carried out under argon atmosphere by means of standard Schlenk techniques. Benzene was purified by Na-benzophenone and distilled before use. 4-ethynylaniline, 5chlorosalicylaldehyde, salicylaldehyde, benzaldehyde, 3,5-di-t-butyl-2-hydroxybenzaldehyde, molecular sieve 5A and silica gel (Wakogel C-300) were obtained from Wako Pure Chemical Industries, Ltd. Molecular sieve 5A was dried under vacuum at 150 °C before use. [CpCo(CO)2] was prepared by known procedure [23]. HPLC was performed using model LC-908 produced by Japan Analytical Industry Co. Mass spectrum was recorded on a JEOL JMSD300. NMR spectra were measured with a JEOL LA500 spectrometer. UV–Vis spectra were recorded on a Hitachi model UV-2500PC.

4.2. Preparation of [CpCo(S2C2(H)(C6H4-NH2))] (1) [CpCo(CO)2] (1.4 ml, 10 mmol), elemental sulfur (0.64 g, 20 mmol) and 4-ethynylaniline (1.72 g, 10 mmol) were reacted in refluxing benzene (50 ml) for 19 h. Solvent was removed under reduced pressure. A blue component was separated by column chromatography on silica gel (eluent = dichloromethane). The blue product (1) was further purified by recrystallization from dichloromethane/n-hexane (10% yield).

4.2.1. Spectroscopic data of 1 Mass (EI+, 70 eV) m/z (rel intensity) 305 (M+, 100), 188 (CpCoSþ 2, 75), 124 (CpCo+, 16). 1H NMR (CDCl3, vs. TMS, 500 MHz) d 8.96 (s, 1H, dithiolene-H), 7.62 (d, 2H, J = 8.9 Hz, Ar), 6.62 (d, 2H, J = 8.9 Hz, Ar), 5.33 (s, 5H, Cp), 4.22 (s, 2H, NH2). UV–vis (CH2Cl2) kmax/nm (e/ M1 cm1) 621 (7900), 294 (30,000). HR-mass (EI+, 70 eV) Calcd. for C13H12CoNS2: 304.9743; Found 304.9749.

1 (31 mg, 0.1 mmol) and 5-chlorosalicylaldehyde (16 mg, 0.1 mmol) were reacted in refluxing benzene (30 ml) for 3 h in the presence of molecular sieve 5A. After the solvent was removed under reduced pressure, a green fraction was separated by column chromatography on silica gel (eluent = dichloromethane). The resulted green product (2a) was further purified by HPLC (eluent = chloroform). 2a was recrystallized by dichloromethane/nhexane and was isolated in 35% yield. 2b was obtained from 1 (0.1 mmol) and salicylaldehyde (0.1 mmol) in 13% yield, 2c was prepared from 1 (0.1 mmol) and benzaldehyde (0.1 mmol) in 12% yield, 2d was also prepared from 1 (0.1 mmol) and 3,5-di-t-butyl-2-hydroxybenzaldehyde (0.1 mmol) by using the similar procedure to that of 2a. 4.3.1. Spectroscopic data of 2a Mass (EI+, 70 eV) m/z (rel intensity) 443 (M+, 100), 188 (CpCoS2+, 66), 124 (CpCo+, 18). 1H NMR (CDCl3, vs TMS, 500 MHz) d 9.04 (s, 1H, dithiolene-H), 8.59 (s, 1H, N@H), 7.88 (s, 1H, Ar), 7.86 (s, 1H, Ar), 7.37 (d, 1H, J = 2.90 Hz, Ar), 7.30 (s, 1H, Ar), 7.25 (d, 1H, J = 2.90 Hz, Ar), 7.24 (s, 1H, Ar), 6.96 (s, 1H, Ar), 5.39 (s, 5H, Cp). UV–vis (CH2Cl2) kmax/nm (e/M1 cm1) 602 (10,600), 375 (22,100), 288.5 (29,000). HR-mass (EI+, 70 eV) Calcd. for C20H15ClCoNOS2: 442.9616; Found 442.9618. 4.3.2. Spectroscopic data of 2b Mass (EI+, 70 eV) m/z (rel intensity) 409 (M+, 67), 188 (CpCoS2+, 100), 124 (CpCo+, 27). 1H NMR (CDCl3, vs TMS, 500 MHz) d 9.05 (s, 1H, dithiolene-H), 8.66 (s, 1H, N@CH), 7.88 (s, 3H, Ar), 7.40 (s, 1H, Ar), 7.26 (s, 3H, Ar), 7.03 (s, 2H, Ar), 6.94 (s, 2H, Ar), 5.39 (s, 5H, Cp). UV–vis (CH2Cl2) kmax/nm (e/M1cm1) 603 (13,000), 367 (29,000), 290 (34,000). HR-mass (EI+, 70 eV) Calcd. for C20H16CoNOS2: 409.0005; Found 409.0010. 4.3.3. Spectroscopic data of 2c Mass (EI+, 70 eV) m/z (rel intensity) 393 (M+, 80), 188 (CpCoS2+, 100), 124 (CpCo+, 60). 1H NMR (CDCl3, vs TMS, 500 MHz) d 9.06 (s, 1H, dithiolene-H), 8.51 (s, 1H, N@CH), 7.91 (t, 2H, J = 4.0 Hz, Ar), 7.86 (d, 2H, J = 8.3 Hz, Ar), 7.49–7.47 (t, 2H, J = 4.0 Hz, Ar), 7.17 (d, 2H, J = 8.3 Hz, Ar), 5.39 (s, 5H, Cp). UV–vis (CH2Cl2) kmax/nm (e) 604 (8600), 361 (16,000), 291 (25,000). HR-mass (EI+, 70 eV) Calcd. for C20H16CoNS2: 393.0056; Found 393.0051. 4.3.4. Spectroscopic data of 2d Mass (EI+, 70 eV) m/z (rel intensity) 521 (M+, 100), 188 (CpCoS2+, 7), 124 (CpCo+, 2). 1H NMR (CDCl3, vs TMS, 500 MHz) d 9.06 (s, 1H, dithiolene-H), 8.68 (s, 1H, N@CH), 7.87–7.85 (m, 2H, Ar), 7.46 (d, 1H, J = 2.1 Hz, Ar), 7.26 (s, 1H, Ar), 7.25 (s, 1H, Ar), 7.22 (d, 1H, J = 2.1 Hz, Ar), 5.39 (s, 5H, Cp) , 1.47 (s, 9H, Me), 1.33 (s, 9H, Me). UV–vis (CH2Cl2) kmax/nm (e/M1 cm1) 603 (11,000), 373 (22,000), 290 (30,000). HR-mass (EI+, 70 eV) Calcd. for C28H32CoNOS2: 521.1257; Found 521.1261. 4.4. CV measurements All electrochemical measurements were performed under an argon atmosphere. Solvents for electrochemical measurements were dried by molecular sieve 4A before use. A platinum wire served as a counter electrode, and the reference electrode Ag/AgCl was corrected for junction potentials by being referenced internally to the ferrocene/ferrocenium (Fc/Fc+) couple. A stationary platinum disk (1.6 mm in diameter) was used as a working electrode. The Model CV-50 W instrument from BAS Co. was used for cyclic voltammetry (CV) measurements. CVs were measured in

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1 mmol dm3 dichloromethane solutions of complexes containing 0.1 mol dm3 tetra-n-butylammonium perchlorate (TBAP) at 25 °C. 4.5. X-ray diffraction study Single crystals of 1, 2a, 2b and 2c were obtained by recrystallization using vapor diffusion of n-hexane into the dichloromethane solution. A single crystal was mounted on the top of a thin glass fiber. The measurement was made on a Rigaku Mercury diffractometer with graphite-monochromated Mo Ka radiation. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods and expanded using Fourier techniques [24]. The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were refined using the riding model. All the calculations were carried out using the Crystal Structure crystallographic software package [25]. Crystallographic data are summarized in Table 3.

[7]

[8]

[9] [10] [11]

[12]

Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.molstruc.2011.11.027. References [1] (a) K. Ogawa, J. Harada, J. Mol. Struct. 647 (2003) 211; (b) J. Harada, K. Ogawa, Nippon Kessho Gakkaishi 51 (2009) 49. [2] (a) J. Harada, T. Fujiwara, K. Ogawa, J. Am. Chem. Soc. 129 (2007) 16216; (b) K. Ogawa, Y. Kasahara, Y. Ohtani, J. Harada, J. Am. Chem. Soc. 120 (1998) 7107; (c) E. Ito, H. Oji, T. Araki, K. Oichi, H. Ishii, Y. Ouchi, T. Ohta, N. Kosugi, Y. Maruyama, T. Naito, T. Inabe, K. Seki, J. Am. Chem. Soc. 119 (1997) 6336. [3] T. Haneda, M. Kawano, T. Kojima, M. Fujita, Angew. Chem., Int. Ed. 46 (2007) 6643. [4] (a) T. Hu, Y.-G. Li, J.-Y. Liu, Y.-S. Li, Organometallics 26 (2007) 2609; (b) M. Chandrakala, B.S. Sheshadri, N.M.N. Gowda, K.G.S. Murthy, K.R. Nagasundara, J. Chem. Res. 34 (2010) 576; (c) N. Hoshino, H. Murakami, Y. Matsunaga, T. Inabe, Y. Maruyama, Inorg. Chem. 29 (1990) 1177; (d) M. Trivedi, M. Chandra, D.S. Pandey, M.C. Puerta, P. Valerga, J. Organomet. Chem. 689 (2004) 879; (e) S. Pal, S.N. Poddar, S. Ghosh, G. Mukherjee, Polyhedron 14 (1995) 3023. [5] (a) I.V. Sazanovich, A. Balakumar, K. Muthukumaran, E. Hindin, C. Kirmaier, J.R. Diers, J.S. Lindsey, D.F. Bocian, D. Holten, Inorg. Chem. 42 (2003) 6616; (b) M. Hayvali, H. Gunduz, N. Gunduz, Z. Kilic, T. Hokelek, J. Mol. Struct. 525 (2000) 215. [6] (a) K.C. Majumdar, S. Chakravorty, N. Pal, R.K. Sinha, Tetrahedron 65 (2009) 7998;

[13]

[14] [15] [16] [17]

[18] [19] [20] [21] [22] [23] [24]

[25]

(b) H. Nawaz, Z. Akhter, S. Yameen, H.M. Siddiqi, B. Mirza, A. Rifat, J. Organomet. Chem. 694 (2009) 2198; (c) O.N. Kadkin, J. An, H. Han, Y.G. Galyametdinov, Eur. J. Inorg. Chem. (2008) 1682; (d) O.N. Kadkin, H. Han, Y.G. Galyametdinov, J. Organomet. Chem. 692 (2007) 5571; (e) B.-X. Ye, Y. Xu, F. Wang, Y. Fu, M.-P. Song, Inorg. Chem. Commun. 8 (2005) 44. (a) M.T. Kaczmarek, M. Kubicki, W. Radecka-Paryzek, Struct. Chem. 21 (2010) 779; (b) B. Li, G. Zhao, G. Tang, Synth. React. Inorg. Met.-Org. Chem. 21 (1991) 1387; (c) W.I. Azeez, A.I. Abdulla, Trans. Met. Chem. 14 (1989) 425. (a) Y. You, H.S. Huh, K.S. Kim, S.W. Lee, D. Kim, S.Y. Park, Chem. Commun. (2008) 3998; (b) C. Li, G. Zhang, H.-H. Shih, X. Jiang, P. Sun, Y. Pan, C.-H. Cheng, J. Organomet. Chem. 694 (2009) 2415. (a) K.C. Majumdar, P.K. Shyam, Mol. Cryst. Liq. Cryst. 528 (2010) 3; (b) H.W. Chae, O.N. Kadkin, M.-G. Choi, Liq. Cryst. 36 (2009) 53. J. Doemer, F. Hupka, F.E. Hahn, R. Froehlich, Eur. J. Inorg. Chem. (2009) 3600. (a) T.B. Rauchfuss, Prog. Inorg. Chem. 52 (2003) 1; (b) S.D. Cummings, R. Eisenberg, Prog. Inorg. Chem. 52 (2003) 315; (c) C. Faulmann, P. Cassoux, Prog. Inorg. Chem. 52 (2003) 399. (a) M. Nomura, Dalton Trans. 40 (2010) 2112; (b) M. Nomura, C. Fujita-Takayama, T. Sugiyama, M. Kajitani, J. Organomet. Chem. 696 (2011) 4018; (c) A. Sugimori, T. Akiyama, M. Kajitani, T. Sugiyama, Bull. Chem. Soc. Jpn. 72 (1999) 879. H. Bönnemann, B. Bogdanovic, W. Brijoux, R. Brinkmann, M. Kajitani, R. Mynott, G.S. Natarajan, M.G.Y. Samson, Transition metal-catalyzed synthesis of heterocyclic compounds, in: J.R. Kosak (Ed.), Catalysis in Organic Reactions, Marcel Dekker, New York, 1984, pp. 31–62. S. Boyde, C.D. Garner, J.A. Joule, D.J. Rowe, J. Chem. Soc. Chem. Commun. (1987) 800. G. Alesso, M. Sanz, M.E.G. Mosquera, T. Cuenca, Eur. J. Inorg. Chem. (2008) 4638. J. Harada, H. Uekusa, Y. Ohashi, J. Am. Chem. Soc. 121 (1999) 5809. M. Nomura, S. Kondo, S. Yamashita, E. Suzuki, Y. Toyota, G.V. Alea, G.C. Janairo, C. Fujita-Takayama, T. Sugiyama, M. Kajitani, J. Organomet. Chem. 695 (2010) 2366. M. Nomura, M. Kajitani, J. Organomet. Chem. 691 (2006) 2691. M. Nomura, M. Kanamori, Y. Yamaguchi, N. Tateno, C. Fujita-Takayama, T. Sugiyama, M. Kajitani, J. Organomet. Chem. 694 (2009) 2902. M. Nomura, T. Sasao, T. Hashimoto, T. Sugiyama, M. Kajitani, Inorg. Chim. Acta 363 (2010) 3647. M. Fourmigué, T. Cauchy, M. Nomura, CrystEngComm 11 (2009) 1491. E.W. Reinheimer, I. Olejniczak, A. Łapin´ski, R. S´wietlik, O. Jeannin, M. Fourmigué, Inorg. Chem. 49 (2010) 9777. T.S. Piper, F.A. Cotton, G. Wilkinson, J. Inorg. Nucl. Chem. 1 (1955) 313. P.T. Beurstkens, G. Admiraal, G. Beurskens, W.P. Bosman, S. Garcia-Granda, R.O. Gould, J.M.M. Smits, C. Smykala, The DIRDIF Program System, Technical Report of the Crystallography Laboratory, University of Nijmegen, Nijmegen, The Netherlands, 1992. Crystal Structure 3.6.0, Single Crystal Structure Analysis Software. Molecular Structure Corp. and Rigaku Corp., The Woodlands, TX/Tokyo, Japan, 2004.