Preparation and properties of molybdenum and tungsten dinitrogen complexes.: 67.: Protonation and methylation of zerovalent molybdenum complexes of the types trans-[Mo(CNR)(L)(Ph2PCH2CH2PPh2)2] (R = Ph or Bun; L = N2, CO, or nitrile) and trans-[Mo(CO) (L′)(Ph2PCH2CH2PPh2)2] (L′ = N2 or nitrile) to give carbyne or hydrido complexes

Treatment of trans-[Mo(CNPh)(N-2)(dppe)(2)] with aqueous HBF4 afforded an aminocarbyne complex, which was isolated as trans-[Mo(=CNHPh)(O=CMe2)(dppe)(2)][BF4] (7) after crystallization of the crude product from acetone-hexane, whereas the reaction of trans-[Mo(CNBun)(N-2)(dppe)(2)] with [Me2OH][BF4] resulted in the formation of the aminocarbene complex with an agostic alpha-C-H bond, trans-[MoF(CHNHBun)(dppe)(2)][BF4]. Analogous treatment of trans-[Mo(CNR)(L)(dppe)(2)] (R = Ph, Bu-n; L = p-MeOC6H4CN, CO (4)) with [Me2OH][BF4] gave aminocarbyne complexes trans-[Mo(=CNHR)(NCC6H4OMe-p)(dppe)(2)][BF4] and cis-[Mo(=CNHR)(CO)(dppe)(2)][BF4] (10). In solution at room temperature, the latter complexes gradually isomerized to the hydride complexes [MoH(CNR)(CO)(dppe)(2)][BF4] (12). Related aminocarbyne complexes cis-[Mo(=CNMeR)(CO)(dppe)(2)][BF4] (13) were obtained from the reactions of 4 with [Me3O][BF4]. For comparison, carbonyl complexes trans-[Mo-(CO)(N-2)(dppe)(2)] and trans-[Mo(CO)(p-MeOC6H4CN)(dppe)(2)] were allowed to react with aqueous HBF4, which revealed the formation of the hydride complexes [MoH(CO)(H2O)(dppe)(2)][BF4] (14) and [MoH(CO)(p-MeOC6H4CN)(dppe)(2)][BF4] (15), respectively. The X-ray analyses were undertaken to determine the detailed structures for 7, 10a (R = Ph), 12a (R = Ph), 13b (R = Bu-n), 14.THF, and 15.Et2O.