GROUP-4 ANSA-METALLACYCLOHEXASELENANES - SYNTHESIS, CHARACTERIZATION,AND PROPERTIES - CRYSTAL-STRUCTURE OF (TI[ME(2)SI(ETA(5)-C5H4)(2)]SE-5)

The ansa-metallacyclohexaselenanes {M[Me(2)Si(eta(5)- C5H4)(2)]Se-5} [ M = Ti (1), Zr (2), Hf (3)] have been synthesized by treating the appr opriate dichlorides {M[Me(2)Si(eta(5)-C5H4)(2)]Cl-2} With a solution o f Li2Se5 prepared in situ. Complexes 1-3 were characterized by element al microanalysis and by IR, H-1 and C-13 NMR spectroscopies. The cryst al structure of 1 has been determined by X-ray crystallography. Crysta ls are triclinic, space group P (1) over bar with Z = 2 in a unit cell of dimensions a = 9.437(4) Angstrom, b = 11.546(4) Angstrom, c = 8.69 5 Angstrom, alpha = 93.62(2)degrees, beta = 96.29(2)degrees, gamma = 1 13.520(12)degrees. The structure consists of discrete molecules of 1 w ith the TiSe5 ring in the chair conformation and it is very similar to that of its sulfur analogue {Ti[Me(2)Si(eta(5)-C5H4)(2)]S-5}.