STEPWISE REACTIONS OF TICL4 AND TI((OPR)-PR-I)CL-3 WITH 2-PROPANOL - VARIABLE-TEMPERATURE NMR-STUDIES AND CRYSTAL-STRUCTURES OF [TICL2((OPR)-PR-I)((HOPR)-PR-I)(MU-CL)](2) AND [TICL2((OPR)-PR-I)((HOPR)-PR-I)(MU-(OPR)-PR-I)](2)

The reactions of TiCl4 and Ti((OPr)-Pr-i)Cl-3 with 1-3 molar equiv of 2-propanol give the dimeric complexes [TiCl3((HOPr)-Pr-i)(mu-Cl)](2) ( 1), [TiCl2((OPr)-Pr-i)((HOPr)-Pr-i)(mu-Cl)](2) (2), and [TiCl2((OPr)-P r-i)((HOPr)-Pr-i)(mu-(OPr)-Pr-i)](2) (3). The reactions are shown to p roceed stepwise with the consecutive addition of 2-propanol. Complexes 2 and 3 are dynamic in solution. However, the proton VT NMR studies s how that they are static and remain the dimeric features in solution a t low temperatures. Two inequivalent methyl environments are observed for the 2-propanol ligand of complex 3, probably due to the intramolec ular hydrogen bonding from the isopropanolic hydrogen to the chloride on the second titanium metal center. 2 crystallizes in the orthorhombi c space group Pbca with cell parameters of a = 12.605(3) Angstrom, b = 12.841(4) Angstrom, c = 15.414(4) Angstrom, Z = 4, D-calcd = 1.456 g/ cm(3), R = 0.049, R(w) = 0.062, and G(OF) = 1.38. 3 crystallizes in th e monoclinic space group P2(1)/c with cell parameters of a = 9.457(2) Angstrom, b = 15.277(2) Angstrom, c = 11.354(4), beta = 112.76(2)degre es, Z = 2, D-calcd = 1.305 g/cm(3), R = 0.032, R(w) = 0.048, and G(OF) = 1.29. Through the analysis of the bonding features of the solid-sta te structures 2 and 3, the relative bonding sequence of (OPr)-O---Pr-i > Cl- > (HOPr)-Pr-i > mu-(OPr)-Pr-i > mu-Cl- is established. This bon ding order is useful for the prediction of the geometries of six-coord inate titanium complexes containing those ligands with the rule ''the strong ligand prefers a position trans to the weak ligand in the compl exes''. Besides, the reaction features demonstrated in this study may apply to the reaction of TiCl4 or Ti((OPr)-Pr-i)Cl-3 with diols, espec ially for chiral diols used as ligands in titanium complexes for vario us asymmetric syntheses of organic compounds.