TY - JOUR A1 - Curtis, NF A1 - Gainsford, GJ A1 - Siriwardena, A A1 - Weatherburn, DC T1 - Compounds of Nickel(II) With trans-6,13-Dinitro- and trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane, with Structural Studies of Five (trans-6,13-Diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II) Compounds JF - Australian Journal of Chemistry JO - Aust. J. Chem. Y1 - 1993 VL - 46 IS - 6 SP - 755 EP - 786 KW - UR - https://doi.org/10.1071/CH9930755 N2 - Compounds of NiII with the macrocyclic ligand trans-6,13-dimethyl-6,13-dinitro-1,4,8,11-tetraazacyclotetradecane ( dino ), which is formed by condensation of bis (ethane-1,2-diamine)nickel(II) salts, nitroethane and formaldehyde, are described, together with homologues formed by substituting propane-1,2-diamine and/or 1-nitropropane. The nitro functions of [Ni( dino )]2+ were reduced by catalytic hydrogenation to form (trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II), [Ni( diam )]2+, isolated as approximately equal amounts of two isomeric forms; designated α (with the R,S,R,S configuration of the chiral nitrogen centres, overall configuration 1α,4α,6β,8α,11α,13α), and β (with the R,R,S,S, 1α,4β,6α,8β,11α,13β configuration). The α-isomer is metastable, and in solution isomerizes to the β-isomer, with rate constant of 5.0(5)×10-5 s-1 in 2 mol l.-1. NaCl solution at 50°C, the rate of this reaction increasing in both acid and base. Protonation constants (pK at 25°C in 0.1 mol l.-1 NaClO4) for diam are 11.2(1), 9.7(1), 6.2(1), 5.3(1), and for the isomeric nickel(II) cations are α 4.94(2), 2.4(5); and β 4.5(1), 4.0(1). Compounds of diam with the β-configuration were prepared with triplet ground state NiII with diam in hexadentate coordination (e.g. β-[Ni(diam-N4)] Cln ) and in tetradentate coordination with the neutral (e.g. trans-β-[Ni(diam-N4)(NCS)2]) or diprotonated ligand (e.g. trans-β-[Ni(diamH2-N4)(NCS)2](CNS)2). Compounds prepared with the α-configuration with triplet ground-state NiII had pentadentate diam with the neutral (e.g. trans-α-[Ni(diam-N5)(H2O)]Cl2) or monoprotonated ligand (e.g. trans-α-[Ni(diamH-N5) Cl ] (ClO4)2). Singlet ground-state NiII compounds with the square planar diprotonated ligand were prepared for both configurations. Structures are reported for β-[Ni(diam-N6)](ClO4)2(H2O), R 0.062 for 5708 reflections; β-[Ni(diam-N6)] [ZnCl4].1.5H2O, R 0.064 for 4332 reflections; β-[Ni(diam-N6)]Cl2.6H2O, R 0.044 for 2001 reflections; trans-β-[Ni(diam-N4)(NCS)2] R 0.056 for 1521 reflections; and trans-α-[Ni(diamH-N5) Cl ](ClO4)2(H2O), R 0.047 for 2667 reflections. ER -