Compounds of nickel(II) with 5 SR,7 RS,12 SR,14 SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane, rmL 2: The structures of [Ni(rmL 2)](ClO 4) 2 · 0.5H 2O and cis-[Ni(rmL 2)(acac)]ClO 4

Abstract

The imine functions of [Ni(mL 1)](ClO 4) 2 (mL 1 = meso-7 RS,14 SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) are reduced by using NaBH 4 in acetonitrile/methanol to form the meso–meso and rac–meso isomeric cyclic tetramine complex cations [Ni(mmL 2)] 2+ and [Ni(rmL 2)] 2+ (mml 2 = 5 RS,7 RS,12 SR,14 SR- and rmL 2 = 5 SR,7 RS,12 SR,14 SR-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 NaBH 4 in ethanol. Square planar singlet ground state ( S = 1) salts [Ni(rmL 2)](ClO 4) 2 and [Ni(rmL 2)][ZnCl 4] and triplet ground state ( S = 3) trans-di-ligand octahedral compounds trans-[Ni(rmL 2)X 2] ( X - = Cl - , Br - , NCS - , N 3 - , NO 3 - , NO 2 - and HCO 3 - ) ,μ-Y- trans-[Ni(rmL 2)Y] ( Y 2 - = C 2 O 4 2 - and [ Ni ( CN ) 4 ] 2 - ) and folded macrocycle compounds cis-[Ni(rmL 2)(acac)]CIO 4 (acac − = pentane-2,4-dionato), cis-[{Ni(rmL 2)} 2(C 2O 4)](ClO 4) 2, cis-[Ni(rmL 2)(H 2O) 2](ClO 4) 2 and cis-[Ni(rmL 2)X 2], X − = Cl −, Br −, are described. The S = 1 salt 1 SR,4 SR,5 SR,7 RS,8 RS,11 RS,12 SR,14 SR-[Ni(rmL 2)](ClO 4) 2 · 0.5H 2O 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) Å. 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-1 SR,4 SR,5 SR,7 RS,8 SR,11 SR,12 SR,14 SR-[Ni(rmL 2)(acac)]ClO 4 has N-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)°}, with mean Ni–N = 2.09(2) Å and mean Ni–O = 2.121(5) Å. 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)]ClO 4, [M(rrL 2)(acac)]CIO 4 and [M(mmL 2)(acac)]ClO 4 compounds are compared.