[(4R,5R)-(2,2-Dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanolato)-κ2 O:O′]bis(N-methylmethanaminato)titanium(IV)

In the title four-coordinate complex, [Ti(C2H6N)2(C31H28O4)], two symmetry-independent molecules are present in the asymmetric unit. The TiIV atom displays a distorted tetrahedral geometry, with Ti—O bond lengths ranging from 1.805 (3) to 1.830 (3) Å and O—Ti—O ligand bite angles of 100.16 (12) and 101.36 (12)°. The short Ti—N bond distances, ranging from 1.877 (4) to 1.905 (4) Å, indicate strong bonding between the TiIV atom and the dimethylamide ligands.

In the title four-coordinate complex, [Ti(C 2 H 6 N) 2 (C 31 H 28 O 4 )], two symmetry-independent molecules are present in the asymmetric unit. The Ti IV atom displays a distorted tetrahedral geometry, with Ti-O bond lengths ranging from 1.805 (3) to 1.830 (3) Å and O-Ti-O ligand bite angles of 100.16 (12) and 101.36 (12) . The short Ti-N bond distances, ranging from 1.877 (4) to 1.905 (4) Å , indicate strong bonding between the Ti IV atom and the dimethylamide ligands.

Experimental
Crystal data [Ti(C 2  about the titanium(IV) metal center with Ti-O bond lengths ranging from 1.805 to 1.830 Å, average 1.82 (1) Å, Ti-N bond lengths ranging from 1.877 to 1.905 Å, average 1.89 (1) Å, and TADDOLate O-Ti-O bite angles of 100.16 (12)°a nd 101.36 (12)° for Ti1 and Ti2, respectively. These Ti-O distances are slightly longer than the average Ti-O distance of 1.78 (2) Å found for the 12 Ti-O distances of the three independent molecules in the crystal structure of Ti(TADDOLate) 2 (Seebach et al., 1992), presumably due to the strongly electron donating dimethylamido groups in the title complex. The observed O-Ti-O bite angles are also slightly less than the average O-Ti-O bite angle of 102.5 (8)° found for the six O-Ti-O bite angles of the three independent molecules in the crystal structure of Ti(TADDOLate) 2 (Seebach et al., 1992), indicating that titanium in title complex has a more strongly distorted tetrahedral coordination geometry than in Under a nitrogen atmosphere, tetrakis(dimethylamido)titanium (28.8 mg, 0.13 mmol) was added to a solution of (4R,5R)-(-)-2,2-dimethyl-α,α,α',α'-tetraphenyl-1,3-dioxolane-4,5-dimethanol (60 mg, 0.13 mmol) in C 6 D 6 (2.5 ml) and the benzene was allowed to slowly evaporate yielding light yellow plate crystals within 7 d.

Refinement
All non-hydrogen atoms were refined anisotropically. H atoms on carbon were included in calculated positions and refined using a riding model at C-H = 0.95, 0.98 or 1.00 Å and U iso (H) = 1.2, 1.5 or 1.2 × U eq (C) of the aryl, methyl and methine C-atoms, respectively. The extinction parameter (EXTI) refined to zero and was removed from the refinement. Fig. 1. A view of the two independent molecules of the title compound, with displacement ellipsoids shown at the 50% probability level.

Figures
Crystal data [Ti(C 2

Special details
Experimental. A suitable crystal was mounted in a nylon loop with Paratone-N cryoprotectant oil and data set was collected on a Bruker APEXII CCD platform diffractometer. The structure was solved using direct methods and standard difference map techniques, and was refined by full-matrix least-squares procedures on F 2 with SHELXTL Version 6.14 (Sheldrick, 2008).
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 Rfactors(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.