Nonsymmetrical nickel PCN pincer complexes [Ni­( iPrPCNX)­Cl] (X = NMe, CH2) are obtained by metalation of the benzene–pyridine-based pincer ligand iPrPCNX (X = NMe, CH2) with [Ni­(dme)­Cl2] (dme = 1,2-dimethoxyethane). These nickel species afforded the respective borohydride and ethyl complexes [Ni­( iPrPCNX)­L] (L = BH4, Et) upon treatment with NaBH4 and EtMgBr (or Et2Mg), respectively. Reacting [Ni­( iPrPCNX)­(κ2-BH4)] with CO2 gave the formate complexes [Ni­( iPrPCNX)­(OCHO)]. Treatment of [Ni­( iPrPCNX)­Cl] with the nitrosyl salt NOBF4 led to the formation of the unusual cationic square-pyramidal nickel nitrosyl pincer complexes [Ni­( iPrPCNX)­(NO)­Cl]+ featuring a strongly bent NO ligand (∠Ni–N–O 128.5°). These systems can be described as {NiNO}10 according to the Enemark–Feltham convention. Despite of the bent nature of the NO ligand the νNO is observed at 1849 cm–1 which is more typical for a linear Ni–N–O arrangement. The structure of these complexes is rationalized by means of DFT calculations. The molecular structures of representative complexes are presented.

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Treatment of [Co2(CO)8 ] with the ipso-substituted P(C-X)PY ligands (X = Br, Cl; R = iPr, tBu) bearing Y = NH and CH2linkers under solvothermal conditions affords the five-coordinate Co(I) and Co(III) complexes [CoI(PCPY-R)(CO)2] and [CoIII(PCPY-R)X2]. The later are paramagnetic exhibiting a solution magnetic moment in the range of 3.0 to 3.3µB which is consistent with a d6 intermediate spin system corresponding to two unpaired electrons. In the case of P(C-X)PY ligands (X = Br, Cl; R = tBu; Y = NH) the formation of the square planar Co(II) complex [Co(PCPNH-tBu)X] was favored. This complex gives rise to a magnetic moment of 1.8 µB being consistent with a d7 low spin system corresponding to one unpaired electron. All complexes are characterized by means of spectroscopic techniques (NMR, IR), HR-MS. Representative complexes were also characterized by X-ray crystallography.