Reactions of Dialkylnickel(II) Complexes NiR2L2 with Alkyl (or Aryl) Halides, R′COY (Y=Cl, Br, OPh, OCOPh), and CS2

Abstract

Abstract Reactions of Ni(CH3)2(bpy) (1), Ni(C2H5)2(bpy) (2) (bpy=2,2′-bipyridine), trans-Ni(CH3)2(triethylphosphine)2 (3), Ni(CH3)2(1,2-bis(diphenylphosphino)ethane) (4), and Ni(CH3)2(1,3-bis(diphenylphosphino)propane) (5) with alkyl or aryl halides, R′COY (Y=Cl, Br, OC6H5, OCOC6H5), and CS2 have been investigated. The reactions of NiR2L2 with alkyl or aryl halides are classified into three types of reactions by their reactirn products: Type A: NiR2L2+R′X→NiX(R′)L2+R–R, Type B: NiR2L2+R′X→alkane (RH)+ olefin (R′(–H)), and Type C: NiR2L2+R′X→NiR(X)L2+R–R′. Complexes 1 and 2 undergo mainly Type A reaction. Complex 3 gives Type A reaction product on treatment with C6H5Br, but it gives Type B reaction product on treatment with C2H5Br. On the other hand, 4 undergoes Type C reaction on interaction with C6H5Cl. The reactions with R′COY (Y=Cl, Br, OPh, OCOPh) are classified into two types of reactions by their reaction products: Type D: NiR2L2+R′COY→NiY(R′)L2+RCOR′ and Type E: NiR2L2+R′COY→NiY(R′)L2+RCOR. Complexes 1–3 undergo mainly Type D reaction, whereas complexes 4 and 5 mainly Type E reaction. The difference in the reaction route is discussed on the basis of presence or absence of vacant coordination site for attack by R′COY. The reaction of 4 with CS2 affords Ni(CS2)(1,2-bis(diphenylphosphino)ethane) with evolution of a reductive elimination product, ethane, whereas the reaction of 3 with CS2 gives a 1:1 adduct of 3 and CS2.