Bis(cyclopentadienyl)methan‐verbrückte Zweikernkomplexe, IV. Synthese, Struktur und Reaktivität von Zweikernkomplexen des Rhodiums und Iridiums in der Oxidationsstufe +I und +III mit dem Bis(cyclopentadienyl)methan‐Dianion als Brückenliganden

Abstract

Bis(cyclopentadienyl)methane‐Bridged Dinuclear Complexes, IV[1]. — Synthesis, Structure, and Reactivity of Dinuclear Rhodium and Iridium Complexes in the Oxidation State +I and +III with the Bis(cyclopentadienyl)methane Dianion as Bridging LigandThe rhodium compounds [CH2(C5H4)2][Rh(L)(C2H4)]2 (2, 4) were prepared from [RhCl(L)(C2H4)]2 (1, 3) and CH2(C5H4)2Li2 in 92 and 73% yield, respectively. The reaction of 4 with Cl2, Br2, and I2 led to the almost quantitative formation of the dihalogeno derivatives [CH2(C5H4)2][RhX2(PiPr3)]2 (6–8), which on treatment with excess NaBH4 and methanol gave the dihydride [CH2(C5H4)2][RhH2(PiPr3)]2 (10). From [RhCl(C8H14)2]2 (12), PiPr3, and CH2(C5H5)2 the chloro(hydrido)rhodium complex [CH2(C5H4)2][RhH(Cl)(PiPr3)]2 (13) was obtained. Protonation of 10 with CF3CO2H in the presence of NH4PF6 gave the PF6 salt of the hydrido‐bridged cation {[CH2(C5H4)2]‐[RhH(PiPr3)]2(μ‐H)}+ (14) of which the crystal structure was determined. In solution, fluxional behavior of the cation was observed. The dimethyl compound [CH2(C5H4)2][Rh(CH3)2‐(PiPr3)]2 (17), prepared from 6, 7, or 8 and LiCH3 or CH3MgI in 80% yield, reacted with CF3CO2H at — 78° C to give the tri‐fluoroacetato derivative 18; this on treatment with P(OMe)3 and dmpe formed the dicationic complexes 19 and 20, respectively. The dinuclear iridium compounds [CH2(C5H4)2]‐[Ir(olefin)2]2 (26, 27) and [CH2(C5H4)2][Ir(C8H12)]2 (28) were prepared from [IrCl(L)2]2 (23–25) and CH2(C5H4)2Li2 and used for the synthesis of {[CH2(C5H4)2][IrX2]2}n (29, 30). Compounds 29 and 30 served as starting materials for the preparation of the dinuclear derivatives [CH2(C5H4)2][IrX2(L)]2 (31–34) and {[CH2(C5H4)2][IrBr2]2(μ‐dipy)} (35) and finally also for the dihydrido complex [CH2(C5H4)2][IrH2(PiPr3)]2 (36).