Nickel(II) Complexes with [2 sup4.3sup1]Adamanzane, 1,4,7,10-Tetraazabicyclo[5.5.3]pentadecane

Nickel(II)complexes with the bicyclic tetraamine L=[2 sup4.3 sup1]adamanzane, ,4,7,10- tetraaza- bicyclo[5.5.3]pentadecane) have been synthesized. The reaction of NiBr sub 2 with [2 sup4.3 sup1]adz in dimethylformamide gives a dibromo-bridged dinuclear complex [{Ni(L)}sub2(mu-Br)sub2]Br sub2. From this crude product pure {Ni(L)}sub2 (mu-Br)sub2](ClO sub4)sub2 and {Ni(L)}sub 2 (mu-Cl)sub 2](ClO sub4)sub2 have been obtained. In aqueous solution these dinuclear species hydrolyse to the parent mononuclear diaqua species, which was isolated as [Ni(L)(H sub2O)sub2]S sub2O sub6 x 2H sub2O. The reaction of the diaqua complex with nitrite gives [Ni(L)(NO sub2)]ClO sub4 or [Ni(L)(NO sub2)]PF sub6 and with nitrate [Ni(L)(NO sub3)]ClO sub4 is obtained. Equilibrium studies of the formation of the nitrito and nitrato complexes are reported. The structures of [{Ni(L)}sub2(mu-Cl) sub2](ClO sub4)sub2, [Ni(L)(H sub2O)sub2]S sub2O sub6 x 2H sub2O, [Ni(L)(NO sub2)]PF sub6 and Ni(L) (NO sub3)]ClO sub4 have been determined by X-ray diffraction techniques. The coordination geometry about the nickel(II) ion is a distorted octahedron in all the structures.