Reactions of Aluminium Tribromide with Tetrakis(triphenylphosphine)nickel(0) and Tetrakis(triethylphosphite)nickel(0) Complexes

Reactions of aluminium tribromide with the Ni(0) phosphine and phosphite complexes are studied by EPR method. AlBr₃was found to cause the oxidation of the transition metal in the (PPh₃)₄Ni complex to the univalent state with the formation of the tetracoordinated (PPh₃)₃NiBr complex. With an excess of AlBr₃, the phosphine ligands are eliminated from the coordination sphere of Ni(I), and the coordinatively unsaturated complexes are destroyed to give the colloidal nickel. In the reaction of (P(OEt)₃)₄Ni with AlBr₃, Ni(0) is also oxidized to Ni(I), but the acido ligand is not eliminated even with a 15-fold excess of the Lewis acid. The activity of catalytic systems on the basis of the Ni(0) phosphine complexes and the Lewis acids in the low-molecular oligomerization reactions of olefines is determined by the cationic coordinatively unsaturated Ni(I) complexes formed in these systems.     

Tris(triphenylphosphan)nickel(0)-Komplexe mit Nitril-Liganden

Tris(triphenylphosphane)nickel(0) Complexes with Nitrile Ligands . Synthesis, properties and reaction behaviour of (Ph₃P)₃Ni(η¹-NCR) (R = PhCH₂, 2-MeC₆H₄, Me₃Si) complexes as well as the X-ray structure of (Ph₃P)₃Ni(η¹-NCSiMe₃) are described. With NC(CH₂)_nBr (n = 1, 2) instead of the analogous nitrile complexes (Ph₃P)₂NiBr₂ and CH₃CN or C₂H₅CN respectively are formed.     

Sigma-borane coordinated to nickel(0) and some related nickel(II) trihydride complexes

The reactions of the complexes [(dcype)NiH]2, 1, [(dippe)NiH]2, 2, and [(dtbpe)NiH]2, 3, with a mixture of BEt3 and Super-Hydride (LiHBEt3) afforded sigma-borane nickel(0) compounds of the type [(dcype)Ni(sigma-HBEt2)], 4, [(dippe)Ni(sigma-HBEt2)], 5, [(dtbpe)Ni(sigma-HBEt2)], 6, respectively, with the concomitant formation in each case of [(dcype)2Ni2)(H)3][BEt4], 7, [(dippe)2Ni2(H)3][BEt4], 8 and [(dtbpe)2Ni2(H)3][BEt4], 9, respectively. X-ray crystal structures are reported for 4 and 8.The reaction of BEt3 and LiHBEt3 was also reviewed in detail.     

New π-carboxo complexes of nickel(0)

The synthesis of several new zerovalent nickel complexes containing carboxo coordinated organic molecules bearing substituents such as CN, CO₂R, CF₃, F, and F₂CCF demonstrates that a range of electron withdrawing functional groups is capable of effecting the necessary activation of the CO bond to cause π-coordination.