P-C bond scission at the TRIPHOS ligand and C-CN bond cleavage in 2-methyl-3-butenenitrile with [Ni(COD)2]

The use of catalytic amounts of [Ni(COD)(2)] and TRIPHOS (bis(2-diphenylphosphinoethyl)phenylphosphine) allows the isomerization of 2-methyl-3-butenenitrile (2M3BN) at 100 degrees C, to yield Z- and E-2-methyl-2-butenenitrile (2M213N) (57% and 31%, respectively), small amounts of 3-pentenenitrile (3PN) (5%), along with a mixture of nickel complexes, consisting of cis- and trans-[Ni-2(mu-P(CH2CH2PPh2)(2))(2)(CN)(2)] (1, 2), cis- and trans- [Ni(TRIPHOS)(CN)21 (3, 4), [Ni(TRIPHOS)] (5), and [Ni-2(mu-P(CH2CH2PPh2)(2))(2)] (6), where compounds 1-4 and 6 are the C-CN and P-C bond cleavage products, respectively. The persistent presence of benzene in the reaction mixture was confirmed by GC-MS. The use of stochiometric amounts of the reagents led to the isomerization of 2M3BN to Z- and E-2M2BN (47% and 44%, respectively) and 3PN (9%); the formation of complexes 2, 5, and 6 has been confirmed to take place, in addition to benzene and 1,3-butadiene. Complexes 1 and 3 were characterized by single-crystal X-ray determinations.