Synthesis and X-ray crystal structure analysis of a phosphorus analogue of (1,2,3-η)-trans-butadienyl complexes

Metalation of the 1-phenyl-2-isopropylidene–phosphirane PW(CO)5 complex (1) by lithium diisopropylamide occurs at the ring CH2 and cleaves the ring to give the corresponding (3,3-dimethyl-allen-1-yl)phenylphosphide P–W(CO)5 complex (2). The reaction of 2 with [CpFe(CO)2I] then yields the μ-phosphido complex 3 whose heating at 110°C finally gives the (1,2,3-η)-trans-1-phenyl-4,4-dimethyl-1-phosphabutadienyl complex (4). The structure of 4 shows the syn-coplanar stereochemistry of the WPCH unit with a short PC bond at 1.773 Å. The methylene substituent forms an angle of 145.4° with the CC bond of the η3-allyl unit.