Nickel(II) compounds of a tri-amine mono-imine macrocycle: Preparations and structures of (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradec-4-ene) nickel(II) compounds

摘要

Reduction of one imine function of (5,7,7,12,14,14-hexamethyl-1,4,8,11- tetraazacyclotetradeca-4,11-diene)nickel(II) with 1 molar proportion of NaBH4 produces as the major product the tri-amine-mono-imine macrocyclic cation (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradec-4- ene)nickel(II), Ni(tm)]~(2+). Pairs of isomeric singlet ground state perchlorate and tetrachlorozincate salts of [Ni(tm)]~(2+) were prepared and the structures determined for the 1RS,8SR,11SR,12RS (labeled as β) and 1RS,8RS,11RS,12SR (labeled as α) tetrachlorozincate salts. Triplet ground state trans-β-[Ni(tm)(NCS)_2] and catena-trans-{β-Ni(tm)-NC- Ni(CN)2-CN-}n·2nH_2O have the macrocycle in planar coordination and α-[{Ni(tm)}_2(C_2O _4)](ClO_4)_2 has the macrocycle folded. With pentane-2,4-dione the compounds [β-Ni(tm)]·[α-Ni(tm)(acac)] (ClO_4)_3 and [Ni(teta)]·[α-Ni(tm)(acac)] (ClO_4)_3 (teta = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11- tetraazacyclotetradecane) with both square-planar and octahedral Ni(II) cations were prepared and the latter was structurally characterized. Isomerisation in solution of metastable α-[Ni(tm)]2+ to stable β-[Ni(tm)]2+ is extremely slow, even in base