The reaction of titanocene bis(ferrocenylacetylide) and bis(ruthenocenylacetylide) with silver cation: formation of bis(Ti-tweezers) silver complexes

Abstract

Titanocene bis(acetylide) where the acetylide has ferrocenyl or ruthenocenyl terminal group (C 5H 4R) 2Ti{(CC) n -Mc} 2, reacted with 0.5 equivalent amount of AgPF 6 giving cationic heptanuclear complexes of the form [(C 5H 4R) 4Ti 2{(CC) n -Mc} 4Ag](PF 6) ( 1a: R=SiMe 3, n=1, Mc=ferrocenyl, 2a: R=H, n=2, Mc=ferrocenyl, 3a: R=SiMe 3, n=2, Mc=ferrocenyl, 4a: R=SiMe 3, n=1, Mc=ruthenocenyl) in good yields. Likewise, complex [(C 5H 4SiMe 3) 4Ti 2(CCPh) 4Ag](PF 6) ( 5a) was isolated. The Ti(IV)–Fe(II)–Ag(I) complex 3a was structurally characterized to confirm the solid-state geometry of the first bis(Ti-tweezers) type chelate complex with silver cation in which the silver was coordinated by four triple bonds of the two titanocene bis(acetylide) moieties. The similar Ti(IV)–Ru(II)–Ag(I) complex 4a was also characterized by single-crystal X-ray analysis. Complex 3a reacted with 1.5 equivalents (with respect to Ti) of AgPF 6 to liberate Fc–(CC) 4-Fc (Fc=ferrocenyl) quantitatively.