GROUP-2 TITANIUM HETEROMETALLIC ALKOXIDES - THEIR REPRODUCIBLE SYNTHESES AND CHARACTERIZATION - CRYSTAL-STRUCTURES OF THE COMPOUNDS [SRTI4(OET)(18)] AND [SR2TI(OPRI)(8)((PROH)-O-I)(3)].2PR(I)OH

The reactions of either (i) bulk metal in alcohol (EtOH or (PrOH)-O-i) ; or (ii) the preformed metal alkoxides, [M(OR)(2)(ROH)(x)](n), with a stoichiometric amount of Ti(OPri)(4) at reflux yielded the novel hydr ocarbon soluble molecular aggregates [MTi2(OEt)(10)(EtOH)(5)](n) [M = Sr (1) and Ba (2)]; [MTi4(OEt)(18)] [M = Sr (3) and Ba (4)]; [M2Ti(OEt )(8)(EtoH)(5)](n), [M = Sr (5) and Ba (6)]; and [Sr2Ti (OPri)(8)((PrOH )-O-i)(3)].2Pr(i)OH (7). All complexes have been characterized by elem ental analyses and spectroscopic methods; (3) and (7) have also been c haracterized by X-ray crystallography. The structure of (3) is based o n a ''bow-tie'' Ti2SrTi2 unit where the strontium is coordinated to tw o face sharing bioctahedral Ti-2(OEt)(9)(-) units, via two ''terminal' ' and two ''bridging'' ethoxo ligands from each Ti-2(OEt)(9)(-) unit. In (7) the Sr2Ti unit forms a triangle, bridged by three mu(2)-(PrO)-O -i ligands and capped by two mu(3)-(PrO)-O-i ligands, and further supp orted by six terminal (PrO)-O-i/(PrOH)-O-i ligands. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.