Inorganic Chemistry, Vol.34, No.23, 5893-5899, 1995
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)(-).
Keywords:NUCLEAR-MAGNETIC-RESONANCE;HETEROMETALLIC ALKOXIDES;CRYSTAL-STRUCTURE;MOLECULAR-STRUCTURE;COMPLEXES;PRECURSORS;REACTIVITY;ARYLOXIDES;OXIDES;BONDS