Preparations and structures of some nickel(II) compounds of 2RS,7SR,9SR,14RS- and 2RS,7RS,9SR,14SR-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane

Reduction of the imine functions of meso-[(3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradec-4,11-diene)nickel(II)] by NaBH4 yields the complex nickel(II) cations of three stereo-isomers of 2,5,5,7,9,12,14,14-octamethyl-1,4,8,11-tetrazacyclotetradecane (L): 2RS,7SR,9SR,14RS (mm1-L), 2RS,7RS,9SR,14SR (mm2-L) and 2RS,7RS,9SR,14RS (mr-L), in ca. 16, 37 and 23% yields respectively. The preparation and structure of [Ni(mm1-L)](ClO4)2 has been reported, but no metal-ion compounds of mm2-L have been reported. The preparations and structures are reported for square-planar singlet ground state salts: [Ni(mm1-L)]ZnCl4, [Ni(mm2-L)]ZnCl4, [Ni(mm2-L)](ClO4)2, [Ni(mm1-L)]Cl2·2H2O and [Ni(mm1-L)](CNS)2. Preparations and structures are reported for the triplet ground state octahedral compounds trans-[Ni(mm2-L)X2], X− = Cl−, N3−, ONO−, and CH3CO2−, trans-[Ni(mm2-L)(OH2)2](NO3)2, trans-[Ni(mm1-L)(N3)2] and trans-[Ni(mm1-L)(NCS)2]·0.5H2O, all with the nitrogen configuration 1R,4S,8S,11R. The mm1-L compounds are all centrosymmetrical with the C2 and C9 methyl substituents axially oriented. The mm2-L compounds, except for [Ni(mm2-L)]-ZnCl4 and -(ClO4)2, have centrosymmetrical octahedral molecules/cations with the C2 and C9 methyl substituents equatorially oriented. The structure of 2RS,7RS,9SR,14SR-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane dihydrate, mm2-L·2H2O, released from the nickel(II) compound by reaction with cyanide, is reported. Structures are also reported for trans-[Ni(teta)X2] (teta = meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetrazacyclotetradecane, X = NO2− and CH3CO2−.