Synthesis and characterization of pentakis(dimethylphosphanyl)cymantrene [Mn{C5(PMe2)5}(CO)3], the first cyclopentadienyl complex with five phosphanyl substituents†

Abstract

Treatment of the highly reactive [Mn(C₅Cl₃Li₂)(CO)₃] with PPh₂Cl or PEt₂Cl gave the 1,3-bis(phosphanyl)cymantrenes [Mn{C₅Cl₃(PR₂)₂}(CO)₃] (R = Ph, 1 or Et 2). The stepwise repeated reaction of [Mn(C₅Br₅)(CO)₃] with ⁿBuLi and PMe₂Cl yielded a 4∶1 mixture of [Mn{C₅H(PMe₂)₄}(CO)₃] 3 and [Mn{C₅(PMe₂)₅}(CO)₃] 4, from which the latter can be isolated in 10% yield. A structure determination of 4 shows a planar cyclopentadienyl ring with a “paddle wheel” conformation of the five PMe₂ substituents.