Polyhetero-ferrocenes and -ruthenocenes derived from the 1,4,2-diphosphastibolyl ring anion [P2SbC2But2]−

The complex [RuCl 2 (PPh 3 ) 3 ] reacted with the 1,4,2-diphosphastibolyl ring anion [P 2 SbC 2 Bu t 2 ] - (containing ca. 25% of the 1,2,4-triphospholyl anion [P 3 C 2 Bu t 2 ] - ) to produce a cocrystallised mixture (crystal structure) of two isomers of [Ru(η 5 -P 2 SbC 2 Bu t 2 ) 2 ] with [Ru(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -P 3 C 2 Bu t 2 )]. Variable-temperature 31 P-{ 1 H} NMR studies on the mixture show one of the isomers and the last complex to be fluxional at room temperature. It is believed that an interring Sb · · · Sb interaction in the other isomer restricts its fluxionality in solution. The reaction of [P 2 SbC 2 Bu t 2 ] - with FeCl 2 yielded only one isomer of the heteroferrocene complex [Fe(η 5 -P 2 SbC 2 Bu t 2 ) 2 ] which is also non-fluxional in solution and has a similar oxidation potential to that of ferrocene itself. The heteroruthenocene complexes [Ru(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 R 5 )] (R = H or Me) were prepared by treating [Ru(η 5 -C 5 R 5 )(MeCN) 3 ] [PF 6 ] (R = H or Me) with [P 2 SbC 2 Bu t 2 ] - . The analogous ferrocene complex [Fe(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 )] (crystal structure) was synthesized by treating a 1∶1 mixture of [P 2 SbC 2 Bu t 2 ] - and Li(C 5 Me 5 ) with half an equivalent of FeCl 2 . Treatment of [M(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 )] (M = Ru or Fe) with [W(CO) 5 (thf)] (thf = tetrahydrofuran) formed the secondary co-ordination complexes [M(η 5 -P 2 SbC 2 Bu t 2 )(η 5 -C 5 Me 5 ){W(CO) 5 }] (M = Ru or Fe) in which the W(CO) 5 fragment is η 1 ligated to the phosphorus centre adjacent to the ring antimony centre. A diphosphastibolyl-bridged cationic triple-decker complex [(η 5 -C 5 Me 5 )Ru(µ-η 5 : η 5 -P 2 SbC 2 Bu t 2 )Ru(η 5 -C 5 Me 5 )][PF 6 ] was the product of the reaction of [P 2 SbC 2 Bu t 2 ] - with 2 equivalents of [Ru(η 5 -C 5 Me 5 )(MeCN) 3 ] [PF 6 ].