METRICAL COMPARISON AND ALKALI-METAL NMR SPECTROSCOPIC INVESTIGATION OF A CONGENER SET OF ALKALI METALATED TITANIUM(IV) ISOPROPOXIDES - X-RAY STRUCTURES OF [NATI(OCHME(2))(5)](INFINITY) AND [KTI(OCHME(2))(5)](INFINITY)

The congeners of the alkali metal substituted titanium isopropoxide compound, [LiTi(OCHMe(2))(5)](2) (a) have been identified as [NaTi(OCHMe(2))s](infinity) (2) and [KTi(OCHMe(2))(5)](infinity) (3). Both 2 and 3 are polymeric species, wherein the alkali metal acts as a bridge between discrete, mononuclear, trigonal-bipyramidal, titanium pentaisopropoxide moieties. The infinite linear chains formed in 2 consist of alternating five coordinate titanium moieties and tetrahedral sodium atoms. Compound 3 forms a nonlinear continuous chain with the potassium atoms in an extremely distorted trigonal-bipyramidal geometry. A comparison of the metrical data of 1-3 and literature data reveals that the bond distances and angles of 1-3 agree with expected values. Compound 2 crystallized from pentane at -25 degrees C in the space group P2(1)/a with a = 12.616(1) Angstrom, b = 10.078(4) Angstrom, c = 17.573(4) Angstrom, and beta = 103.20 degrees, for Z = 4. Least squares refinement of the model based on 3801 reflections (\F-o\ > 3.0 sigma(\F-o\)) converged to a final R(F) = 8.57%. Crystals of 3 formed in the space group P2(1)/n with a 12.213(2) Angstrom, b = 9.792(2) Angstrom, c = 18.442(3) Angstrom, and beta = 106.944(12)degrees, for Z = 4. Least squares refinement of the model based on 3083 reflections (\F-o\ > 3.0 sigma(\Fo\)) converged to a final R(F) = 4.2%. Alkali metal (Li-7, Na-23) NMR spectroscopy data reveal that, in solution, 1 exists as a dimer with rapid alkoxide ligand exchange, whereas, for 2, a tight ion pair exists between Na+ and the Ti(OCHMe(2))(5)(-).