Protonation and alkylation reactions at phosphaalkenyl carbyne complexes Tp′(CO)2MC-P=C(NR′2)2 [Tp′ = HB(3,5-Me2C3HN2)3, M = Mo, W, R = Me, Et]

Reaction of the carbyne complexes Tp'(CO)(2)M=C-P=C(NR2)(2) (1, 2) [Tp' = HB(3,5-Me2C3HN2)(3); M = Mo (1, 3); W (2, 4); R = Me (a); Et (b)] with methyl trifluorornethanesulfonate afforded the orange-red salts [Tp'(CO)(2)M=C-P(Me)C(NR2)(2)]SO3CF3 (3, 4), the cations of which can be considered as methylphosphines featuring additional bisaminocarbenium- and metallaalkynyl substituents. Analogously, complex Tp'(CO)(2)W=C-P=C(NEt2)(2) (2b) was protonated with ethereal HBF4 in ether at the phosphorus atom to give [Tp'W=C-P(H)-C(NEt2)(2)]BF4 (5), which in CH2Cl2 solution experienced a clean rearrangement to the metallaphosphirene [Tp'(CO)(2)W=C(H)PC(NEt2)(2)]BF4 (6) Treatment of 2b with F3CSO3H led directly to [Tp'(CO)(2)W=C(H)-PC(NEt2)(2)]SO3CF3 (6'). The molecular structures of 4b and 6' were established by X-ray structure analysis.