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 °C, to yield Z- and E -2-methyl-2-butenenitrile (2M2BN) (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 (μ-P(CH 2 CH 2 PPh 2 ) 2 ) 2 (CN) 2 ] ( 1, 2 ), cis- and trans- [Ni(TRIPHOS)(CN) 2 ] ( 3, 4 ), [Ni(TRIPHOS)] ( 5 ), and [Ni 2 (μ-P(CH 2 CH 2 PPh 2 ) 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.