| Abstract
| - The reactions of TiCl4 andTi(OiPr)Cl3 with 1−3 molar equiv of2-propanol give the dimeric complexes[TiCl3(HOiPr)(μ-Cl)]2(1),[TiCl2(OiPr)(HOiPr)(μ-Cl)]2(2), and[TiCl2(OiPr)(HOiPr)(μ-OiPr)]2(3). The reactions are shown to proceed stepwise withthe consecutive addition of 2-propanol. Complexes 2 and3 are dynamic in solution. However, they are static andremain the dimeric features in solution at low temperatures.Through the analysis of the structural features of the solid-statestructures of 2 and 3, the relative bondingsequence -OiPr > Cl->HOiPr > μ--OiPr >μ-Cl- isestablished.
- The reactions of TiCl4 andTi(OiPr)Cl3 with 1−3 molar equiv of2-propanol give the dimeric complexes[TiCl3(HOiPr)(μ-Cl)]2 (1),[TiCl2(OiPr)(HOiPr)(μ-Cl)]2(2), and[TiCl2(OiPr)(HOiPr)(μ-OiPr)]2(3). The reactions are shownto proceed stepwise with the consecutive addition of 2-propanol.Complexes 2 and 3 are dynamic insolution.However, the proton VT NMR studies show that they are static andremain the dimeric features in solution at lowtemperatures. Two inequivalent methyl environments are observedfor the 2-propanol ligand of complex 3,probablydue to the intramolecular hydrogen bonding from the isopropanolichydrogen to the chloride on the second titaniummetal center. 2 crystallizes in the orthorhombic spacegroup Pbca with cell parameters of a =12.605(3) Å, b =12.841(4) Å, c = 15.414(4) Å, Z =4, Dcalcd = 1.456 g/cm3,R = 0.049, Rw = 0.062, andGOF = 1.38. 3 crystallizesin the monoclinic space group P21/cwith cell parameters of a = 9.457(2) Å, b= 15.277(2) Å, c = 11.354(4),β = 112.76(2)°, Z = 2,Dcalcd = 1.305 g/cm3, R= 0.032, Rw = 0.048, and GOF =1.29. Through the analysis ofthe bonding features of the solid-state structures 2 and3, the relative bonding sequence of-OiPr > Cl->HOiPr> μ--OiPr > μ-Cl- isestablished. This bonding order is useful for the prediction ofthe geometries of six-coordinate titanium complexes containing those ligands with the rule“the strong ligand prefers a positiontransto the weak ligand in the complexes”. Besides, the reactionfeatures demonstrated in this study may apply to thereaction of TiCl4 orTi(OiPr)Cl3 with diols, especiallyfor chiral diols used as ligands in titanium complexes forvarious asymmetric syntheses of organic compounds.
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