Cp 2Ti IV und Cp 2Zr IV-Komplexe mit Pyrazintetracarboxylat-Liganden

Abstract

The reaction of titanocene dichloride with tetrasodium pyrazinetetracarboxylate in the two-phase system of water/CHCl 3 gives the tetranuclear complex [Cp 2Ti(C 8N 2O 8)TiCp 2] 2 ( 4′) which can be isolated as the hydrate [Cp 2Ti(C 8N 2O 8)TiCp 2] · 12H 2O ( 3 or the crystalline solvate [Cp 2Ti(C 8N 2O 8)TiCp 2] 2 · 2H 2O · 2CHCl 3 · 3CH 3NO 2 ( 4) from an appropriate mixture of solvents. Two of the titanium atoms in 4′ are penta-coordinate (Cp 2TiO 2N arrangement) and the other two are tetra-coordinate (Cp 2TiO 2 arrangement). The pyrazinetetracarboxylate (4 −) anions act as (3 + 1 + 1)-dentate ligands. The heterometallic complex [Cp 2Ti(C 8N 2O 8)ZrCp 2] 2 ( 10′) which crystallizes as the solvate [Cp 2Ti(C 8N 2O 8)ZrCp 2] 2 · CH 3NO 2 · 6CHCl 3 ( 10) is isostructural with 4′. The reaction of equimolar amounts of Cp 2TiCl 2 and Cp 2ZrCl 2 with tetrasodium pyrazinetetracarboxylate gives 10. The Zr atoms in 10′ occupy the penta-coordinate positions whereas the Ti atoms occupy the tetra-coordinate positions. 4 reacts with aqueous hydrochloric acid to give the penta-coordinate mononuclear complex Cp 2Ti(C 8H 2N 2O 8) ( 11′) which crystallizes as the solvate Cp 2Ti(C 8H 2N 2O 8) · 2H 2O · CH 3NO 2 ( 11). The crystal structures of 4, 10, and 11 have been determined by X-ray diffraction.