CRYSTAL-STRUCTURE AND SPECTROSCOPIC AND MAGNETIC-PROPERTIES OF 2 CIS-AZIDO CATENAS OF NICKEL(II) - CIS-CATENA-MU-N3)[NI(BIPY)2](X) (X=CLO4,PF6)

The compounds cis-catena-(mu-N3)[Ni(bipy)2](ClO4) (1) and cis-catena-( mu-N3)[Ni(bipy)2](PF6) (2) (where bipy = 2,2'-bipyridine) have been sy nthesized and characterized. Both crystallize in the monoclinic P2(1)/ c space group. For 1, a = 20.830(3) angstrom, b = 15.497(4) angstrom, c = 13.90(1) angstrom, beta = 101.72(3)-degrees, V = 4393(3) angstrom3 , Z = 4, R = 0.065, and R(w) = 0.070. In the case of compound 2, a = 2 1.173(3) angstrom, b = 15.781(2) angstrom, c = 13.930(4) angstrom, bet a = 100.04(2)-degrees, V = 4583(2) angstrom3, Z = 4, R = 0.071, and R( w) = 0.075. The nickel(II) ions are octahedral with the two bipy ligan ds and end-to-end azido bridges in a cis-arrangement. This configurati on of the azido bridges has not been reported so far. Magnetic measure ments of both compounds show strong antiferromagnetic couplings betwee n the nickel cations through the azido ions. The obtained exchange par ameters are J = -33.0 cm-1 for the perchlorate compound 1 and J = -22. 4 cm-1 for the hexafluorophosphate complex 2, with a gyromagnetic tens or value of g = 2.15 in both cases. The magnetic behavior has been com pared with that of the trans-azido chains known in the literature and analyzed by extended Huckel MO calculations.