Nucleophilic Aromatic Addition Reactions of the Metallabenzenes and Metallapyridinium: Attacking Aromatic Metallacycles with Bis(diphenylphosphino)methane to Form Metallacyclohexadienes and Cyclic eta(2)-Allene-Coordinated Complexes

Abstract

The reactions of phosphonium-substituted metallabenzenes and metallapyridinium with bis(cliphenylphosphino)methane (DPPM) were investigated. Treatment of [Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)]Cl with DPPM produced osmabenzenes [Os( CH C(PPh3)CHC(PPh3)CH}Cl{(PPh2)CH(PPh)]Cl-2(-), [OsICHC(PPH3)CHC(PPh3)CHCI(PPh2)CH-[Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)], and cyclic osmium eta(2)-allene complex [Os[CH=C(PPh3)CH= (eta(2)-C=CH)}Cl-2{(PPh2)CH=PPh2)}(2)]Cl (4). When the analogue complex of osmabenzene 1. ruthenabenzene [Ru- (CHC(PPh3)CHC(PPIOCHICI,-[Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)], was used, the reaction produced ruthenacyclohexadiene [RuICH=C( PPh3)CH=C(PPIOCH)CH(PPh3)CH2(PPh,)),1C1-, (6). which could be viewed as a Jackson Meisenheimer complex. Complex 6 is unstable in solution and can easily he convert to the cyclic ruthenium 112-allelic corn- plexes 1Ru(CH=C(PP113)CH=N2-(= CH)101[Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)](7) and [[Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)]}C12- 1(PPIOCH2(P131)2)121C1 (8). The key intermediates of the reactions have been isolated and fully characterized, further supporting the proposed mechanism for the reactions. Similar reactions also occurred in phosphonium-substituted metallapyridinium [Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)]Cl {CHC(PPH3)CHC(PPH3) to give the cyclic osmium 1C-allene-imine complex{CHC(PPH3)CHC(PPH3)[Os{CHC(PPH3)CHC(PPH3)CHCl2-(PPh3)(2)]Cl .