Synthesis of polymetallic Group 4 complexes bridged by benzenediolate and triolate ligands. X-ray crystal structure of [{Ti(C 5Me 5)Cl 2} 2{μ-1,4-O(2,3-C 6H 2Me 2)O}

Abstract

This paper reports the synthesis of polymetallic complexes in which two or three Group 4 metals are linked to a benzene core through oxo groups. Four methods have been evaluated for the synthesis of such derivatives: from the appropriated alcohol with (a) methyl complexes via methane elimination, (b) chloride compounds in the presence of a Lewis base, or (c) a zirconium hydride, and (d) from the lithium salt of the alcohol and chloride complexes. Method a has been used for the synthesis of bimetallic and trimetallic (pentamethylcyclopentadienyl)titanium(IV) complexes [{Ti(C 5Me 5)Cl 2} 2{μ-1,4-O(C 6H 2XY)O}] (X=Y=H ( 1); X=H, Y=Me ( 2); X=Y=Me ( 3)), [{Ti(C 5Me 5)Me 2} 2{μ-1,4-O(C 6H 2Me 2)O}] ( 4), and [{Ti(C 5Me 5)X 2} 3(μ 3-1,3,5-C 6H 3O 3)] (X=Cl ( 7), Me ( 8)) from the corresponding hydroquinones 1,4-HO(2,3-C 6H 2XY)OH (X=Y=H, Me; X=H, Y=Me) or 1,3,5-trihydroxibenzene and [Ti(C 5Me 5)Cl 2Me] or [Ti(C 5Me 5)Me 3], respectively. Bis(cyclopentadienyl)titanium bimetallic complex [{Ti(C 5H 5) 2Cl} 2{μ-1,4-O(C 6H 2Me 2)O}] ( 5) is better prepared by method d by treatment of the dilithium salt Li 2[1,4-O(2,3-C 6H 2Me 2)O] with [Ti(C 5H 5) 2Cl 2] whereas the trimetallic compound [{Ti(C 5H 5) 2Cl} 3(μ 3-1,3,5-C 6H 3O 3)] ( 9) can be prepared directly from 1,3,5-trihidroxybenzene in the presence of NEt 3 (method b). Finally, bis(cyclopentadienyl)zirconium complexes [{Zr(C 5H 5) 2Cl} 2{μ-1,4-O(C 6H 2Me 2)O}] ( 6) and [{Zr(C 5H 5) 2Cl} 3(μ 3-1,3,5-C 6H 3O 3)] ( 10) are obtained from [Zr(C 5H 5) 2ClH] (method c). The structure of complex 3 has been determined by X-ray diffraction methods.