Synthesis and structures of paramagnetic binuclear (eta(8)-1,4-bis(trimethylsilyl)cyclooctatetraenide)titanium(III) chlorides

The reaction between equimolar quantities of TiCl3(THF)(3) and 1,4-bis(trim ethylsilyl)cyclooctatetraene dianion (COT ") yields a mixture of (COT ")(2) Ti (1), [(COT ")Ti](2)(mu-Cl)(3) (2) and [(COT ")Ti(mu-Cl)](2)(THF) (3). Cr ystalline 2 and 3 were isolated on the basis of different solubility in hex ane. Their X-ray diffraction analyses revealed dimeric structures linked by chlorine bridges. In 3, only one of the Ti atoms coordinates one molecule of THF. The mixed-valency Ti(III)/Ti(IV) compound 2 shows an ESR spectrum t ypical of mononuclear (COT ")Ti(III) complexes. The ESR spectra of 3 in tol uene or 2-methyltetrahydrofuran glasses prove the triplet state of coupled Ti(III) d(1) electrons. (C) 1999 Elsevier Science S.A. All rights reserved.