Synthesis, structure and magnetic properties of several nickel-azido complexes with tetraammines as blocking ligands

The structure of the compound [Ni(TMCY)(N,)](ClO4) (1) has been revised and the new compounds [Ni(TMCY)(N-3)](PF6) (2), [Ni(323-tet)(N-3).(H2O)]Cl . H2O (3) and (mu-N-3)(2)[Ni(232-tet)](2)(PF6)(2) (4) have been synthesized and structurally characterized. TMCY is N,N',N',N ''-tetramethyltetraazacyclote, 323-tet is N,N'-bis-(3-aminopropaneamine)-1,2-ethanediamine and 232-tet is N,N'-bis(2-ethaneamine)-1,3-propanediamine. 1 and 2 are isostructural and crystallize in the orthorhombic system, space group Pmnb, with FW=456.62 (502.15), a=9.671(2) (9.953(2)), b=14.359(3) (14.593(3)), c=14.805(3) (14.594(3)) Angstrom, V=2055.9(7) (2119.7(7)) Angstrom(3), Z=4, R=0.053 (0.042), respectively. The nickel atom is placed in a square pyramidal environment. 3 crystallizes in the triclinic system, group P1, with FW=346.50, a=7.628(3), b=7.756(3), c=7.714(3) Angstrom, alpha=80.55(2), beta=70.84(2), gamma=73.70(2)degrees, V=412.5(5) Angstrom(3), Z=1, R=0.059. The nickel atom is placed in an octahedral NiN5O environment. 4 crystallizes in the monoclinic system, group P2(1)/n, with FW=911.92, a=12.237(4), b=13.657(4), c=9.970(3) Angstrom, beta=107.95(3)degrees, V=1585(1) Angstrom(3), Z=2, R=0.063. Compounds 1, 2 and 3 are monometic whereas 4 consists of dinuclear entities with the azido ligand acting as a double bridge in the end-on mode. Synthetic trends and magnetic behavior are discussed.