SYNTHESIS, CHARACTERIZATION, AND STRUCTURAL INVESTIGATION OF THE FIRST BIOINORGANIC TITANOCENE(IV) ALPHA-AMINO-ACID COMPLEXES PREPARED FROMTHE ANTITUMOR AGENT TITANOCENE DICHLORIDE

Antitumor active titanocene dichloride [Cp(2)TiCl(2)] (Cp = eta(5)-C5H 5) reacts with alpha-amino acids (aa = amino acid) in aqueous methanol to give the first bioinorganic titanium(IV) amino acid complexes [Cp( 2)Ti(aa)(2)](2+)[Cl](-)(2) (aa: glycine, 1; L-alanine, 2; 2-methylalan ine, 3). These compounds are of great interest as the first models inv olving titanocene complexes with cx-amino acids. The structure of 3 wa s determined by X-ray structure analysis. Complex 3 is monoclinic, spa ce group C2/c, a = 9.0630(11) Angstrom, b = 28.173(9) Angstrom, C = 8. 8967(9) Angstrom, beta 96.379(9)degrees, V = 2257.5(4) Angstrom(3), an d Z = 4. It was established by X-ray analysis and vibrational spectros copy that these compounds represent examples of very rare species in w hich the amino acids coordinate solely through the carboxylato group. All complexes have been characterized by chemical analyses (C/H/N/Cl), NMR (H-1, N-14/15), mass (EI; 3 in addition by DCI), infrared, and Ra man spectroscopy.