Peter Moore

Synthesis and coordination chemistry of 1-(2′,2″-bipyridyl-5′-yl-methyl)-1,4,8,11-tetraazacyclotetradecane L1. Quenching of fluorescence from [Ru(bipy)2(L1)]2+ by coordination of NiII or CuII in the cyclam cavity (bipy = 2,2′-bipyridine; cyclam = 1,4,8,11-tetra-azacyclotetradecane)

A novel bipy derivative of cyclam (L1) designed for controlled and systematic polynuclear metal complex formation is reported; fluorescence quenching of the [Ru(bipy)3]2+ core of [(bipy)2Ru(L1)]2+ upon coordination of CuII at the cyclam cavity is demonstrated.

High-pressure NMR kinetics. Part 12. High-pressure carbon-13 FT-NMR. Acetonitrile exchange with hexakisacetonitrilecobalt(2+) perchlorate

Modifications to a recently described high pressure, high resolution NMR probe-head to improve sensitivity and allow observation of carbon-13, are described. Variable temperature and pressure carbon-13 studies on the nitrile resonance of pure acetonitrile in the pressence of [Co(CH3CN)6](ClO4)2 yield the following parameters for the solvent exchange rate: k298.15 = (2.56 ± 0.06) × 105 s−1, ΔH* = 48.79 ± 1.10 kJ mol−1, ΔS* = +22.2 ± 3.7 J K−1, ΔV* = +7.7 ± 1.7 cm3 mol−1. The results are discussed in terms of the relative accuracy and reliability of ΔS* and ΔV*, the parameters most frequently use for solvent exchange mechanistic assignment

Synthesis of pyridine-containing tetra-aza macrocycles: 3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L1), its 3,11-dibenzyl (L2) and 3,7,11-tribenzyl (L3) derivatives, and their nickel(II), copper(II), and zinc(II) complexes: crystal structures of L2·HCL and [Ni(L2)Cl]ClO4·H2O

Three pyridine-containing 14-membered-ring tetra-aza macrocycles, 3,7,11,17-tetra-azabicyclo-[11.3.l]heptadeca-1(17),13,15-triene (L1), its 3,11-dibenzyl (L2) and 3,7,11-tribenzyl (L3) derivatives, and their metal complexes with Ni2+, Cu2+, and Zn2+ have been prepared and characterised. The structure of [Ni(L2)Cl] ClO4·H2O has been established by X-ray crystallography. The Ni2+ ion co-ordination is approximately square pyramidal, with the macrocycle folded about an axis defined by the two N–CH2Ph groups, the secondary amine group co-ordinated at the apex of the square pyramid, and the chloride ion in the basal plane along with the other three N-donor atoms (Cl– in a trans position to the pyridine N atom). The crystal structure of L2·HCl is also reported.

Crystal structure of an antiferromagnetically coupled µ-carbonato-bridged dinickel(II) complex containing the pendent-arm macrocycl 1-(3-dimethylaminopropyl)-1,5,9-triazacyclododecane (L1); a system which readily sequesters carbon dioxide from air

The nickel(II) complex of the pendent-arm macrocycle 1-(3-dimethylaminopropyl)-1,5,9-triazacyclododecane (L1) sequesters CO2 from air to yield, after addition of thiocyanate ion, [{(HL1)Ni(NCS)}2(CO3)]2+, the first example of a µ-carbonato dinickel(II) complex; the Ni atoms are antiferromagnetically coupled with the exceptionally large exchange constant –2J= 94.6 ± 0.4 cm–1.

Studies of pendant arm macrocyclic ligands. Part 6. Synthesis of two penta-aza macrocyclic ligands containing single pendant co-ordinating 2-pyridylmethyl and 1-pyrazolylmethyl arms, and characterisation of their nickel(II), copper(II), cobalt(II), and zinc(II) complexes. Crystal structure of {3,11-dibenzyl-7-(2′-pyridylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]-heptadeca-1(17),13,15-triene}zinc(II) perchlorate

Reaction of the secondary amine group of 3,11-dibenzyl-3,7,11,17-tetrazabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L2) with 2-chloromethylpyridine in the presence of base, or with 1-(hydroxymethyl)pyrazole, gives two new pendant-arm macrocycles, L3 and L4, having 7-(2′-pyridylmethyl) and 7-(1′-pyrazolylmethyl) groups, respectively. Complexes of Co2+, Ni2+, Cu2+, and Zn2+ with L3 and L4 have been isolated and characterised. The structure of [Zn(L3)][ClO4]2 has been established by X-ray crystallography, and confirms solution 1H n.m.r. studies; the two benzyl groups and the pendant arm lie on the same side of the macrocycle. Protondecoupled 13C n.m.r. spectra of the Zn2+ complexes of L3 and L4 show the presence of only a single symmetric isomer in each case. In the [Zn(L4)(dmso)]2+ ion, the presence of a strongly co-ordinated dimethyl sulphoxide (dmso) molecule is confirmed both in the solid state and in solution, and solid complexes of formula [M(L)(dmso)][ClO4]2(L = L3 or L4; M = Co, Ni, or Cu) have been prepared in all cases.

Studies of pendant-arm macrocyclic ligands. Part 8. Synthesis of two pentaazamacrocycles based upon pyridine-containing tetraazamacrocycles with a single pendant co-ordinating 2-pyridylmethyl arm, and characterisation of their nickel(II), copper(II) and zinc(II) complexes. Crystal structure of 7-(2′-pyridylmethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-trienezinc(II) tetrafluoroborate

Two new quinquedentate pentaazamacrocycles, 7-(2′-pyridylmethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene L1 and its 3,11-dimethyl derivative L2, have been characterised, together with their metal complexes of formulae [ML(OH2)][BF4]2(M = Ni or Cu) and [ZnL][BF4]2(L = L1 or L2). The crystal structure of [ZnL1][BF4]2 shows a distorted square-pyramidal geometry, with the Zn 0.59 A above the plane of the macrocyclic ring in the direction of the pendant co-ordinated pyridyl group.

Synthesis and co-ordination chemistry of the pyridyl pendant-arm azamacrocycles 1-(2-pyridylmethyl)-1,5,9-triazacyclododecane L1 and 1-(2-pyridyl-2′-ethyl)-1,5,9-triazacyclododecane L2, with nickel (II), copper(II) and zinc(II). Crystal structures of [Ni(L1)(O2NO)]NO3 and [ZnL2][Zn(NO3)3.67Cl0.33]

The azamacrocyclic ligands 1-(2-pyridylmethyl)-1,5,9-triazacyclododecane L1 and 1-(2-pyridyl-2′-ethyl)-1,5,9-triazacyclododecane L2 have been prepared, and their complexes with hydrated nickel(II), copper(II) and zinc(II) nitrates have been isolated. The nickel(II) complexes are high spin and six-co-ordinate, whilst 13C NMR spectroscopy shows that [ZnL1(OH2)]2+ exists as a symmetric trigonal-bipyramidal isomer in solution, and [ZnL2]2+ exists as a 2:1 mixture of tetrahedral and asymmetric trigonal-bipyramidal isomers. X-Ray crystallography has been used to determine the solid-state structures of the octahedral [NiL1(O2NO)]+, and the tetrahedral isomer of [ZnL2]2+.

Stopped-flow fourier-transform NMR and NMR line broadening studies of the rates of dimethyl sulphoxide exchange with the hexakis(dimethylsulphoxide) complexes of aluminium(III), gallium(III) ions in nitromethane solution

Abstract Stopped-flow Fourier-transform NMR and conventional NMR line broadening experiments have been used to determine rate data for dimethyl sulphoxide (DMSO) exchange with the [M(DMSO) 6 ] 3+ ions (M = Al(III), Ga(III)) in nitromethane-d 3 solution over a temperature range of 105 K (Al(III) and 112 K (Ga(III)). Data previously reported for [Al(DMSO) 6 ] 3+ ion have been extended to higher temperatures and a correction made to the published results. At 298.2 K, rate parameters associated with the exchange of a single solvent molecule are: for [Ga(DMSO) 6 ] 3+ ion, k I ex = 1.87 ± 0.05 s −1 , ΔS* = 72.52 ± 0.48 kJ mol −1 , ΔS* = +3.51 ± 1.54 JK −1 mol −1 ; and for [Al(DMSO) 6 ] 3+ ion, k I ex = 0.302 ± 0.017 s −1 , ΔH* = 82.64 ± 1.16 kJ mol −1 , ΔS* = 22.31 ± 3.64 JK −1 mol −1 . The exchange rates are independent of the un-coordinated DMSO concentration, and dissociative mechanisms are postulated in both cases. For [In(DMSO) 6 ] 3+ ion the rate of solvent exchange is too fast to measure accurately with a 60 MHz spectrometer even at low temperatures.

Synthesis and co-ordination chemistry of 1-(2′,2″-bipyridyl-6′-ylmethyl)-1,4,7-triazacyclononane, a penta-azamacrocycle based on a triazamacrocycle with a single pendent co-ordinating bipyridyl group

New penta- and hexa-azamacrocycles have been synthesised, based on tri- and tetra-azamacrocycles functionalised with a single pendent co-ordinating 2,2′-bipyridyl-6-ylmethyl-arm; for the quinquedentate ligand 1-(2′,2″-bipyridyl-6′-ylmethyl)-1,4,7-triazacyclononane, the formation of a six-co-ordinate complex of Ni2+, and a seven-co-ordinate complex of Zn2+ has been established by X-ray crystallography, and a five-co-ordinate complex of Pd2+ established by 13C n.m.r. and fast atom bombardment mass spectroscopy.

Dissociative substitution in four-co-ordinate planner platinium(II) complexes. The kinetic of sulphoxide exchange and its displacement by bidentate ligands in the reactions of cis- di(aryl)bis(dimethyl sulphoxide) platinum(II) in chloroform and benzene

A parallel flow 1H n.m.r. and u.v. spectrophotometric study of the exchange of Me2SO with (CD3)2SO, and the displacement of Me2SO by L–L [L–L = 2,2′-bipyridine, 1,10-phenanthroline, and 1,2-bis(diphenylphosphino)ethane] from cis-[Pt(Ph)2(Me2SO)2] in CDCl3 and benzene indicates that the main reaction path is dissociative with [Pt(Ph)2(Me2SO)] as the reactive intermediate.