3-Diphenylphosphino-(1R)-(+)-camphor dimethylhydrazone and its complexes with Group 6 metal carbonyls: crystal structures of the hydrazone and [Mo(CO)4(PPh2C10H15NNMe2)]

Abstract

Prolonged treatment of (1R)-(+)-camphor with 1,1-dimethylhydrazine gives (1R)-(+)-camphor dimethylhydrazone 3a which with LiBu, followed by PPh₂Cl, gives the corresponding compound 3c which has the Ph₂P group in 3-exo position and the CN–NMe₂ group in the Z configuration. This new phosphine was quaternized with Mel to give a phosphonium salt and converted into the corresponding sulphide and oxide. Treatment of [M(CO)₄(nbd)](M = Cr, Mo or W; nbd = norbornadiene) with 3c gives [[graphic omitted]NMe₂)]4 in which the phosphine is chelated to the metal in a six-membered ring. However, when [Mo(CO)₆] was heated with 3c in decane, isomerization around the CN bond occurred and the isomeric complex [[graphic omitted]NMe₂)]5 was formed. When 4a was heated in diglyme it isomerized to 5. Proton and ³¹P-{¹H} NMR and infrared data are given. Crystals of compound 3c are orthorhombic, space group P2₁2₁2₁ with a= 1119.9(2), b= 1166.3(2), c= 1690.7(2) pm and Z= 4; final R factor 0.0443 for 3910 observed reflections. Crystals of complex 5 are orthorhombic, space group P2₁2₁2₁, with a= 974.8(2), b= 1658.9(4), c= 1982.0(4) pm and Z= 4; R 0.0425 for 2991 observed reflections. The structure shows that the co-ordinated PPh₂ group is in the 3-exo position whilst the CNNMe₂ moiety is co-ordinated through the CN nitrogen, giving a five-membered co-ordinated ring and an unco-ordinated NMe₂ group. The arrangement around the CN is E, i.e. the opposite to that in 3c.