Di-μ-oxido-bis({2,2′-[ethane-1,2-diylbis(nitrilomethanylylidene)]diphenolato}titanium(IV)) chloroform disolvate

In the title structure, [Ti2(C16H16N2O2)2O2]·2CHCl3, the Ti atom is coordinated in a distorted octahedral geometry by the O,N,N′,O′ donor set of the salalen ligand and by two μ2-oxide O atoms, which bridge two Ti(salalen) fragments into a centrosymmetric dimeric unit. In the central Ti2(μ2-O)2 fragment, the metal–oxygen distances are significantly different [1.7962 (19) and 1.9292 (19) Å]. In the crystal, the chloroform molecule is anchored via an N—H⋯Cl and a bifurcated C—H⋯(O,O) hydrogen bond. Slipped π–π stacking [shortest C⋯C distance = 3.585 (4) Å] and C—H⋯π interactions contribute to the coherence of the structure.


Related literature
For general background to the chemistry affording the tetradentate salalen ligand, see: Matsumoto et al. (2005Matsumoto et al. ( , 2007. For the crystal structure of a salalen complex, see: Taylor et al. (2006). For the structure of the parent titanium salen compound, see: Tsuchimoto (2001). For our previous work on titanium(IV) complexes with polydentate N,O-ligands, see: Zaitsev et al. (2006Zaitsev et al. ( , 2008 Table 1 Hydrogen-bond geometry (Å , ).

Comment
As a part of our investigation on chemistry of titanium complexes based on tridentate or tetradentate ligands (Zaitsev et al., 2006(Zaitsev et al., , 2008 we obtained and studied the structure of the titanium compound [(salalen)TiO] 2 .
The title titanium salalen complex is centrosymmetric. Both Ti atoms are linked by µ 2 -oxo briges and possess a distorted octahedral coordination environment with cis interligand angles ranging from 81.27 (9) to 101.11 (8) In the crystal, the solvent chloroform molecule forms bifurcated C-H···O hydrogen bond with the main molecule with C···O separations of 3.257 (4) and 3.506 (4) Å.
To the best of our knowledge, the title compound represents the second example of structurally characterized salalen complex (Taylor et al., 2006).

Experimental
The several crystals of the title salalen complex were unexpectedly obtained after attempt to recrystallize the parent [(salalen)TiO] 2 (Tsuchimoto, 2001) compound from a hexane-chloroform mixture.

Refinement
Amine hydrogen atom H2 was found from difference Fourier synthesis and its positional parameters were refined using U iso (H2) as 1.2U eq of the parent nitrogen atom. All other hydrogen atoms were placed in calculated positions and refined using a riding model with C-H = 0.95 -1.00 Å and U iso (H) = 1.2U eq (C).

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.