Bis[2-({[2-(methylsulfanyl)phenyl]imino}methyl)phenolato-κ2 N,O]zinc chloroform disolvate

The monomeric title complex, [Zn(C14H12NOS)2]·2CHCl3 or L 2Zn·2CHCl3, where L is the 2-({[2-(methylsulfanyl)phenyl]imino}methyl)phenolate anion, may be obtained by the reaction of LZnEt with benzyl alcohol or by the reaction of two equivalents of LH with ZnEt2 in tetrahydrofuran. The Zn atom, located on a twofold axis, is four-coordinated in a distorted tetrahedral geometry by two O atoms [Zn—O = 1.9472 (19) Å] from the phenolate anions and two imine N atoms [Zn—N = 2.054 (2) Å].

The monomeric title complex, [Zn(C 14 H 12 NOS) 2 ]Á2CHCl 3 or L 2 ZnÁ2CHCl 3 , where L is the 2-({[2-(methylsulfanyl)phenyl]imino}methyl)phenolate anion, may be obtained by the reaction of LZnEt with benzyl alcohol or by the reaction of two equivalents of LH with ZnEt 2 in tetrahydrofuran. The Zn atom, located on a twofold axis, is four-coordinated in a distorted tetrahedral geometry by two O atoms  Å ] from the phenolate anions and two imine N atoms  (2) Å ].

Related literature
For backgroud to poly(lactide) (PLA) and its copolymers, see: Huang et al. (2007). For the use of bulky ligands coordinated to the active metal centre to avoid undesirable transesterification during synthesis by ring-opening polymerization (ROP) of lactides, see: Wu et al. (2006). Many complexes with bulky ligands have been designed for this function, incorporating a single active metal site, see: Wu et al. (2006). For the preparation of a series of Zn complexes with N,N,O-tridentate Schiff bases, which have great activity in the ROP of lactides, see: Chen et al. (2006). For the 2-(2,6-diisopropylphenylimino)methyl)-4-nitrophenolate anion, see: Chisholm et al. (2001).

Experimental
Crystal data [Zn(C 14  Financial support from the National Science Council of the Republic of China is gratefully appreciated. Helpful comments from the reviewers are also greatly appreciated. Because of their potential applications in many fields, poly(lactide) (PLA) and its copolymers have been investigated intensively (Huang et al., 2007). Ring-opening polymerization (ROP) of lactides is the major method used to synthesize these polymers. In these processes, undesirable transesterification reaction is the drawback but it can be lessened by using bulky ligands coordinated to the active metal centre (Wu et al., 2006). A lot of complexes with bulky ligands have been designed for this function, incorporating a single active metal site (Wu et al., 2006). Lin group have prepared a series of Zn complexes with NNO-tridentate Schiff base supported (Chen et al., 2006) which have great activity in the ROP of lactides. Recently, we have prepared NOS-tridentate Schiff base ligand (2-(((2-methylthiophenyl)methylimino)methyl)phenol) and its Zn complex. During these studies, it has been observed that LZnEt, where L is the (2-(((2-methylthiophenyl)methylimino)methyl)phenolate anion (C 14 H 12 NOS), reacts with benzyl alcohol to give L 2 Zn, (I) because of disproportionation. It seems that the sulfur atom can not stabilize Zn atom to form Zn alkoxide complex. L 2 Zn can also be prepared by the reaction of 2 equal LH with ZnEt 2 in tetrahydrofuran. In the solid state, complex (I) shows a monomeric structure in which Zn atom are tetracoordinated and the geometry around Zn, resemble distorted tetrahedral with N-Zn

Experimental
To a suspension of LH (4.86 g, 20 mmol) in tetrahydrofuran (15 ml) was added ZnEt 2 (1.22 g, 10 mmol). After being stirred for 3 hr, volatile materials were then removed under a vacuum to yield a yellow powder. The powder was washed twice with hexane (30 ml), and a high yellow powder was obtained after filtration. The crystal was obtain in CHCl 3 soultion. A colourless crystal was selected from this sample.

Refinement
X-ray experimental: Data were collected at 173 K on a Siemens SMART PLATFORM equipped with A CCD area detector and a graphite monochromator utilizing MoKaradiation (l= 0.71073 Å).Cell parameters were refined using up to 8192 reflections. A full sphere of data (1850 frames) was collected using the w-scan method (0.3°frame width).The first 50 frames were re-measured at the end of data collection to monitor instrument and crystal stability (maximum correction on I was < 1%).Absorption corrections by integration were applied based on measured indexed crystal faces. their respective carbon atoms.A total of 195 parameters were refined in the final cycle of refinement using 3345 reflections with I > 2 s(I) to yield R 1 and wR 2 of 4.37% and 12.30%, respectively.Refinement was done using F 2 .

Bis[2-({[2-(methylsulfanyl)phenyl]imino}methyl)phenolato-κ 2 N,O]zinc chloroform disolvate
Crystal data [Zn(C 14  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.50 e Å −3 Δρ min = −0.50 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.