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-octamethy1-1,4,8,1 1-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-octamethy1-1,4,8,11-tetrazacyclotetradecane (L): 2RS,7SR,9SR,14R5 (mml-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)]Cl-2 center dot 2H(2)O and [Ni(mm1-L)](CNS)(2). Preparations and structures are reported for the triplet ground state octahedral compounds trans-[Ni(mm2-L)X-2], X- =Cl-, N-3(-), ONO-, and CH3CO2-, trans-[Ni(mm2-L)(OH2)(2)](NO3)(2), trans-[Ni (mml-L)(N-3)(2)] and trans-[Ni(mm1-L)(NCS)(2)]center dot 0.5H(2)O, all with the nitrogen configuration 1R,4S,8S,11R. The mml-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-octamethy1-1,4,8,11-tetraazacyclotetradecane dihydrate, mm2-L center dot 2H(2)O, released from the nickel(II) compound by reaction with cyanide, is reported. Structures are also reported for trans-[Ni(teta)X-2] (teta = meso-5,5,7,12,12,14-hexamethy1-1,4,8,11-tetrazacyclotetradecane, X = NO2- and CH3CO2-. (C) 2017 Elsevier Ltd. All rights reserved.