Synthesis, Structure, and Ring-Expansion Reactions of a 3-Ferrocenyl-Substituted 2H-Azaphosphirene Tungsten Complex

Reaction of C‐ferrocenyl‐substituted aminocarbene tungsten complex 1 with [bis(trimethylsilyl)methylene]chlorophosphane (2) and triethylamine yielded 2H‐azaphosphirene complex 3 in good yield. Reaction of complex 3 with aryl nitriles 4a–c, N‐piperidinonitrile (4d), and acetonitrile (4e) in the presence of ferrocenium hexafluorophosphate yieldedregioselectively 2H‐1,4,2‐diazaphosphole complexes 5a–e through single‐electron‐transfer‐induced ring expansion together with complex 6 in varying amounts; isolation of the latter failed. Apart from the NMR spectroscopic parameters of complexes 1, 3, and 5a–e, cyclic voltammetric (1, 3, 5a–d), and single‐crystal X‐ray diffraction data (1, 3, and 5d) are presented and discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) Synthesis and reactions of the first C‐ferrocenyl‐substituted 2H‐azaphosphirene complex 3 are presented. Under oxidativesingle‐electron transfer conditions, and by using ferrocenium hexafluorophosphate as a mild oxidant, complex 3 reacted with various nitrile derivatives 4 to give regioselectively 2H‐1,4,2‐diazaphosphole complexes 5.