Compounds of nickel(II) with 5SR,7RS,12SR, 14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane, rmL2 :: The structures of [Ni(rmL2)](ClO4)2 • 0.5H2O and cis-[Ni(rmL2)(acac)]ClO4

The imine functions of [Ni(mL(1)])ClO4)(2) (mL(1) = meso-7RS,14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) are reduced by using NaBH4 in acetonitrile/methanol to form the meso-meso and rac-meso isomeric cyclic tetramine complex cations [Ni(mmL(2))](2+) and [Ni(mL(2))](2+) (mml(2) =5RS,7RS,12SR,14SR- and rmL(2) = 5SR,7RS, 12SR, 14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane) in ca. 8:1 proportions. [Ni(rmL(2))](2+) is also prepared from rmL(2), formed in < 1% yield by the reduction of mL(1) by NaBH4 in ethanol. Square planar singlet ground state (S = 1) salts [Ni(rmL(2))](ClO4)(2) and [Ni(rmL(2))][ZnCl4] and triplet ground state (S=3) trans-di-ligand octahedral compounds trans-[Ni(rmL(2))X-2] (X- = Cl-,Br-,NCS- N-3(-) NO3-,NO2- and HCO3-), mu-Y-trans-[Ni(rmL(2))Y] (Y2- = C2O42- and [Ni(CN)(4)](2-)) and folded macrocycle compounds cis-[Ni(rmL)(acac)]ClO4 (acac(-) = pentane-2,4-dionato), cis-[{Ni(rmL(2))}(2)(C2O4)](ClO4)(2), cis-[Ni(rmL(2))(H2O)(2)](ClO4)(2) and cis-[Ni(rmL(2))X-2], X- = Cl-, Br-, are described. The S=1 salt 1SR,4SR,5SR,7RS,8RS,11RS12SR,14SR-[Ni(rmL(2))]- (ClO4)(2) (.) 0.5H(2)O has a disordered structure with Ni(II) in square planar coordination by the nitrogen atoms of the macrocycle, in N-configuration III. with Ni-N-mean = 1.96(2) angstrom. The six-membered chelate rings both have chair conformations, with the phenyl substituents equatorially oriented and with the methyl substituents disordered over axial and equatorial orientations. The S = 3 compound cis-1SR,4SR,5SR,7RS,8SR,11SR,12SR,14SR-[Ni(rmL(2))(acac)]ClO4 has Ar-configuration V. The macrocycle is folded along N-1-Ni-N-8, adjacent to the phenyl substituents {N1-Ni-N8 = 176.45(6) N4-Ni-N11 = 98.16(6)degrees}, with mean Ni-N = 2.09(2) angstrom and mean Ni-O = 2.121(5) angstrom. Both six-membered chelate rings have chair conformations with the methyl substituents equatorially oriented, while one has the phenyl substituent equatorially and the other has it axially oriented. The structures of the isomeric [M(rmL(2))(acac)ClO4, [M(rrL(2))(acac)]ClO4 and [M(mmL(2))(acac)]ClO4 compounds are compared. (c) 2005 Elsevier Ltd. All rights reserved.