The cyclo-C 3 ligand: trimetallic cyclopropenium complexes of Group 6–8 metals, including the X-ray crystal structure of [{Fe(CO) 2(Cp)} 3(μ 3-C 3)][SbF 6

Abstract

Several trimetallic cyclopropenium cations have been prepared via reactions of three equivalents of a metallate anion with [C 33Cl 3][SbF 6]. The X-ray crystal structure of [{Fe(CO) 2(Cp)} 3(μ 3-C 3)][SbF 6] ( 1) shows a nearly equilateral C 3 ring with an iron center bonded to each vertex. The cyclopropenium complexes [{Ru(CO) 2(Cp)} 3(μ 3-C 3)][SbF 6] ( 2), [{Mo(CO) 3(Cp)} 3(μ 3-C 3)][SbF 6] ( 3), [{W(CO) 3(Cp)} 3(μ 3-C 3)][SbF 6] ( 4), and [{Re(CO) 5} 3(μ 3-C 3)][SbF 6] ( 5) were spectroscopically characterized. Because of the 3-fold symmetrical nature of these complexes, their NMR spectra display a single cyclo-C 3 ring carbon resonance and a single set of resonances for the metal moiety. Compound 1 reacts with Li[BHEt 3] and LiMe to give complex reaction mixtures. We were not able to add a fourth metal center to the C 3 ring of 1. The spectroscopically characterized C 9 complex [{Fe(CO) 2(Cp)} 3{μ 3-C 3(CC) 3}][SbF 6] ( 6), prepared by the reaction of three equivalents of [Fe(CCSiMe 3)(CO) 2(Cp)] with [C 33Cl 3][SbF 6], was not stable enough to isolate in analytically pure form.