Synthesis and spectroscopic characterization of five-coordinate complexes of Ni2+ based on N-3-macrocycles and salicylaldiminates. Crystal structure of [Ni(9-Me-N-3-mc)(OC6H4CH=NC6H5-o)](ClO4) (9-Me-N-3-mc=2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene)

Five-coordinate nickel(II) complexes of the type [Ni(N-3-macrocycle) (OC6H4CH=NR-o)](+) (N-3-macrocycle=2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene, N-3-mc, or its 9-methyl derivative, 9-Me-N-3-mc) have been prepared by reaction between [{Ni-3(N-3-macrocycle) (mu-OH)}(2)](+) and the appropriate arylsalicylaldimine. An X-ray diffraction study carried out with the complex [Ni(9-Me-N-3-mc)(OC6H4CH=NC6H5-o)](ClO4) has established that the Ni atom presents a square pyramidal coordination and is displaced 0.30 A out of the basal plane towards the apical N1 atom (a=8.552(2), b=33.398(3), c=9.630(3) Angstrom, beta=91.67(1)degrees, monoclinic, space group P2(1)/a, V=2749(1) Angstrom(3), Z=4, D-calc=1.40 g cm(-3), R=0.058, R(w)=0.066). These paramagnetic species have been studied by H-1 NMR, The characteristic pattern of N-3-mc and 9-Me-N-3-mc has been established and the specific assigment of salicylaldimine resonances has been achieved by NOE measurements. The solution electronic spectra of the complexes are also suggestive of five-coordinate geometry in solution.