A novel linkage isomeric pair of mixed ligand Ni(II)complexes with IM2py-kappa~2N,O and IM2py-kappa~2N,N modes in [Ni(acac)(tmen)-(IM2py)]~+;synthesis and X-ray structure

摘要

This is the first report of a Ni(II)complex with the six-membered IM2py chelate coordinating via oxygen,[Ni(acac)(tmen)(IM2py-kappa~2N,O)]PF_6(1 centre dot PF_6)(acac=acetylacetonate;tmen=N,N,N',N'-tetramethylethylenediamine;IM2py=2-(2-(pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-l-oxy).This new complex 1-PF_6 has been synthesized by the direct reaction between [Ni(acac)(tmen)]PF_6 and IM2py.The X-ray analysis(monoclinic,P2_1/c,a=15.378(2),b=13.331(2),c=16.560(2)A,beta=116.377(6)deg,Z=4)demonstrated that the IM2py ligand is coordinated to Ni(II)as an unprecedent six-membered didentate chelate with the kappa~2N,O mode in 1.The corresponding linkage isomer,[Ni(acac)(tmen)(IM2py-kappa~2N,N]PF_6(2-PF_6),was obtained from the deoxygenation reaction of [Ni(acac)(tmen)(NIT2py)]PF_6 with NaNO_2.Variable-temperature measurements of the magnetic susceptibility and UV-vis absorption bands indicated a ferromagnetic interaction in 2 centre dot PF_6 and an antiferro-magentic one in 1 centre dot PF_6.These facts confirm a linkage isomeric pair of [Ni(acac)(tmen)(IM2py-kappa~2N,O)]~+(1)and [Ni(acac)(tmen)(IM2py-kappa~2N,N)]~+(2)with oxygen and nitrogen coordination,respectively,in the IM moiety.