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 Complexes1

Treatment of trans -[Mo(CNPh)(N 2 )(dppe) 2 ] with aqueous HBF 4 afforded an aminocarbyne complex, which was isolated as trans -[Mo(⋮CNHPh)(O CMe 2 )(dppe) 2 ][BF 4 ] ( 7 ) after crystallization of the crude product from acetone−hexane, whereas the reaction of trans -[Mo(CNBu n )(N 2 )(dppe) 2 ] with [Me 2 OH][BF 4 ] resulted in the formation of the aminocarbene complex with an agostic α-C−H bond, trans -[MoF(CHNHBu n )(dppe) 2 ][BF 4 ]. Analogous treatment of trans -[Mo(CNR)(L)(dppe) 2 ] (R = Ph, Bu n; L = p -MeOC 6 H 4 CN, CO ( 4 )) with [Me 2 OH][BF 4 ] gave aminocarbyne complexes trans -[Mo(⋮CNHR)(NCC 6 H 4 OMe- p )(dppe) 2 ][BF 4 ] and cis -[Mo(⋮CNHR)(CO)(dppe) 2 ][BF 4 ] ( 10 ). In solution at room temperature, the latter complexes gradually isomerized to the hydrido complexes [MoH(CNR)(CO)(dppe) 2 ][BF 4 ] ( 12 ). Related aminocarbyne complexes cis -[Mo(⋮CNMeR)(CO)(dppe) 2 ][BF 4 ] ( 13 ) were obtained from the reactions of 4 with [Me 3 O][BF 4 ]. For comparison, carbonyl complexes trans -[Mo(CO)(N 2 )(dppe) 2 ] and trans -[Mo(CO)( p -MeOC 6 H 4 CN)(dppe) 2 ] were allowed to react with aqueous HBF 4, which revealed the formation of the hydrido complexes [MoH(CO)(H 2 O)(dppe) 2 ][BF 4 ] ( 14 ) and [MoH(CO)( p -MeOC 6 H 4 CN)(dppe) 2 ][BF 4 ] ( 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 ·Et 2 O.