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

Abstract

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.

trans-Cyano(6-methyl-1,4,8,11-tetraazacyclotetradecan-6-amine)cobalt(III) bis(perchlorate) hydrate andtrans-hydroxo(6-methyl-1,4,8,11-tetraazacyclotetradecan-6-amine)cobalt(III) bis(perchlorate)

“…The related hexaamine L 2 may bind in a hexadentate (Bernhardt et al, 1989(Bernhardt et al, , 1991, pentadentate Curtis et al, 1993) or tetradentate (Curtis et al, 1992;Bernhardt, Lawrance, Patalinghug et al, 1990) mode, depending on the protonation state of the pendant amines and the preferred coordination geometry of the metal ion. When bulky substi-tuents are attached to one of the pendant amines of L 2 (e.g.…”

The preparation and structure of [trans-dichloro-{trans-6,13-dimethyl-6,13-bis-(N,N-dimethylformamidinyl)-1,4,8,11-tetraazacyclotetradecane}nickel(II)] diperchlorate dihydrate

“…The dimensions, configuration and conformation of the {Ni(diam)} residue are essentially the same as those observed for trans-[Ni(diam) (NCS) 2 ] [4], with Ni1\N1 = 2.058(1), Ni1\N4 = 2.058(1), Ni1\Cl2= 2.5203(4)Å; N1\Ni1\N4 =85.87(5), N1\Ni1\N4(−x + 2, −y, −z + 2) = 94.13(5), N1\Ni1\Cl2 = 92.96(4) and N1\ Ni1\Cl2= 87.04(4)°. The octahedral geometry, Ni\N and Ni\Cl bond lengths (and d-d-spectrum) indicate the presence of triplet ground state nickel(II).…”

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a b s t r a c tReaction of (trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II) perchlorate with oxalyl chloride in dimethylformamide forms trans-dichloro- 4,8,nickel(II) diperchlorate dihydrate. This has a centrosymmetrical cation with nickel(II) in octahedral coordination by the four secondary amine nitrogen atoms of the macrocycle, and with chloride ions coordinated axially.

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Cyanocobalt(III) complexes of penta- and tetradentate-coordinated macrocyclic hexaamines

“…The cis isomer of L is also known (Bernhardt et al, 1992(Bernhardt et al, , 1993. The ligand L is quite versatile and has been shown to bind in a hexadentate (Bernhardt et al, 1989(Bernhardt et al, , 1997, pentadentate Curtis et al, 1992Curtis et al, , 1993 or tetradentate (Comba et al, 1986;Bernhardt, Lawrance, Patalinghug et al, 1990;Bernhardt et al, 1997) mode, depending on whether both, one or no primary amines are coordinated, respectively. The mode of coordination is governed by the metal ion preferences, the synthetic procedures (heat and solvent) and the presence of competing ligands.…”