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Solid-state decomposition of [V3O(O2CPh)6(H2O)3]Cl at 300 °C followed by alcoholysis of the product gives the new vanadium complexes [V6O6(PhCO2)6(CH3O)6(CH3OH)3] (1), [V6O6(PhCO2)6(C2H5O)6(C2H5OH)3] (2), [V6O6(PhCO2)6(C3H7O)6(C3H7OH)3] (3), [V6O6(PhCO2)6(C4H9O)6(C4H9OH)3] (4) and [V4O4(OCH3)6(O2CPh)2(HOCH3)2] (5). Complexes 2, 3and 5have been crystallographically characterised. DC magnetic susceptibility studies on complex 3shows antiferromagnetic coupling leading to a S= 0 spin ground state.

The first structural characterization of an actinide complex with coordinated perrhenate is reported, [UO₂(ReO₄)₂(TPPO)₃] (1). In this {UO₂}2+ complex two [ReO₄]− anions and three TPPO (triphenylphosphine oxide) P&z.dbd;O donor ligands are coordinated in the equatorial plane in a cisoid arrangement. This bonding arrangement, and apparent strain observed in the equatorially bonded ligands, is attributed to the solid state packing in adjacent molecules in which hydrophobic TPPO ligands form an effective “shell” around a hydrophilic core of two UO₂(ReO₄)₂ moieties. Solid state vibrational spectroscopy (infrared and Raman), 31P CP MAS NMR and elemental analysis are also consistent with the formula of 1. Solution state vibrational spectroscopy and 31P NMR measurements in EtOH indicate the lability of the TPPO and [ReO₄]− groups. The photolytic generation of peroxide in EtOH solutions of 1 leads to the formation of trace quantities of [{(UO₂)(TPPO)₃}₂(µ₂-O₂)][ReO₄]₂, 2, in which the coordinated [ReO₄]− groups of 1 have been displaced by bridging O₂2−, derived from atmospheric O₂. Finally, attempts to synthesise a {NpO₂}+ analogue of 1 have resulted only in the formation of [NpO₂(TPPO)₄][ReO₄], 3, in which [ReO₄]− acts solely as a counter anion. From these results it can be concluded that [ReO₄]− will bond to {UO₂}2+, but will be readily displaced by a more strongly coordinating ligand (e.g. peroxide) and will not coordinate to an actinyl cation with a lower charge, {NpO₂}+, under the same reaction conditions.

The first structural characterization of an actinide complex with coordinated perrhenate is reported, UO2ReO42TPPO31. In this UO22complex two ReO4−anions and three TPPO triphenylphosphine oxide PO donor ligands are coordinated in the equatorial plane in a cisoidarrangement. This bonding arrangement, and apparent strain observed in the equatorially bonded ligands, is attributed to the solid state packing in adjacent molecules in which hydrophobic TPPO ligands form an effective “shell” around a hydrophilic core of two UO2ReO42moieties. Solid state vibrational spectroscopy infrared and Raman, 31P CP MAS NMR and elemental analysis are also consistent with the formula of 1. Solution state vibrational spectroscopy and 31P NMR measurements in EtOH indicate the lability of the TPPO and ReO4−groups. The photolytic generation of peroxide in EtOH solutions of 1leads to the formation of trace quantities of UO2TPPO32µ2-O2ReO42, 2, in which the coordinated ReO4−groups of 1have been displaced by bridging O22−, derived from atmospheric O2. Finally, attempts to synthesise a NpO2analogue of 1have resulted only in the formation of NpO2TPPO4ReO4, 3, in which ReO4−acts solely as a counter anion. From these results it can be concluded that ReO4−will bond to UO22, but will be readily displaced by a more strongly coordinating ligand e.g.peroxide and will not coordinate to an actinyl cation with a lower charge, NpO2, under the same reaction conditions.

Nickel and cobalt heterocubanes have been synthesised from dinuclear complexes. The use of 8-hydroxyquinaldine leads to a rhombohedral distortion in two faces of the cubes. Both cubes were studied by paramagnetic NMR, which shows that they are stable in solution. Magnetic measurements show that the coupling within both molecules is overall antiferromagnetic. The magnetic data for the nickel cube has been modelled, and shows that the coupling consists of two ferromagnetically coupled pairs which are antiferromagnetically coupled to give a diamagnetic ground state.

The reaction of the complex [Ni₂(H₂O)(piv)₄(Hpiv)₄] (1) (Hpiv = pivalic acid) with Hppo (3-phenylpyrazolin-5-one) in the presence of a base of an alkaline-earth metal (MII = MgII, SrII or BaII) has led to three different NiII clusters whose structures are controlled by the nature of MII. The formulae of the new heteronuclear cages are [Ni₆Mg₂(OH)₂(ppo)₄(piv)₁₀(Hppo)₄(MeOH)₂] (2), [Ni₈Sr(OH)₂(ppo)₆(piv)₁₀(Hppo)₅(Hpiv)₂(MeCN)] (3) and [Ni₈Ba(OH)₂(ppo)₆(piv)₁₀(Hppo)_5.3(Hpiv)_0.7(MeCN)₂] (4). Magnetic measurements indicate that the spin ground state of 2 consists of two independent S = 3 units, while the presence of two non-interacting S = 2 fragments in the molecule is postulated for compounds 3 and 4.

The synthesis and characterisation of the mercury(ii) complexes [RHg{(SePiPr₂)₂N}] [R = methyl (2a), ethyl (3a), thienyl (T) (4a), 2-selenyl (SL) (5a) and phenyl (6a)], prepared by the reaction of the sodium salt of NH(SePiPr₂)₂ (1a) with the appropriate alkyl/aryl mercury halide in methanol are reported. Results are compared and contrasted to the corresponding sulfur analogues [RHg{(SPiPr₂)₂N}] [R = T (4b), SL (5b) and Ph (6b)], and these new compounds have been evaluated, by thermogravimetric analysis and mass spectrometry as potential precursors and powder X-ray diffraction used to identify solid-state products. The solid-state structure of the symmetrical complex Hg[(SePiPr₂)₂N]₂ 7a, and di(2-selenyl)mercury, one of the symmetrisation products of [SLHg{(SePiPr₂)₂N}] 5a in solution, have been determined by single crystal X-ray crystallography.

The syntheses and the crystal structures of (NH₄)₁₁[LnIII(PMo₁₁O₃₉)₂]·16H₂O (LnIII = Ce (1), Sm (2), Dy (3) or Lu (4)) are reported in which an LnIII cation is sandwiched between two ‘lacunary’ [PMo₁₁O₃₉]7− anions to give a complex with eight oxygen atoms coordinated to the lanthanide centre in a twisted square antiprismatic geometry. This analogous series of complexes represents only the second time that the [PMo₁₁O₃₉]7− anion has been fully crystallographically characterised. All four compounds are synthesised in high yield and characterised by a range of physical and spectroscopic techniques. 31P NMR, Raman and UV/Vis/nIR spectroscopies give a clear indication that the [LnIII(PMo₁₁O₃₉)₂]11− anion is also stable in solution. As LnIII contracts across the lanthanide series the Ln–O bond distances decrease and the splitting of the ν_P–O vibrational mode within the [PMo₁₁O₃₉]7− unit increases. The relative stability of this species in solution may have importance in elucidating the speciation of Ln(iii) and An(iii) cations in nuclear waste solutions where phosphopolymolybdate anions are known to form.

The reaction of the complex Ni2H2Opiv4Hpiv41 Hpiv pivalic acid with Hppo 3-phenylpyrazolin-5-one in the presence of a base of an alkaline-earth metal MII MgII, SrIIor BaII has led to three different NiIIclusters whose structures are controlled by the nature of MII. The formulae of the new heteronuclear cages are Ni6Mg2OH2ppo4piv10Hppo4MeOH22, Ni8SrOH2ppo6piv10Hppo5Hpiv2MeCN 3 and Ni8BaOH2ppo6piv10Hppo5.3Hpiv0.7MeCN24. Magnetic measurements indicate that the spin ground state of 2consists of two independent S 3 units, while the presence of two non-interacting S 2 fragments in the molecule is postulated for compounds 3and 4.

The synthesis and characterisation of the mercuryii complexes RHgSePiPr22N R methyl 2a, ethyl 3a, thienyl T (4a), 2-selenyl SL (5a) and phenyl 6a, prepared by the reaction of the sodium salt of NHSePiPr221a with the appropriate alkylaryl mercury halide in methanol are reported. Results are compared and contrasted to the corresponding sulfur analogues RHgSPiPr22N R T 4b, SL 5b and Ph 6b, and these new compounds have been evaluated, by thermogravimetric analysis and mass spectrometry as potential precursors and powder X-ray diffraction used to identify solid-state products. The solid-state structure of the symmetrical complex Hg(SePiPr22N27a, and di2-selenylmercury, one of the symmetrisation products of SLHgSePiPr22N 5ain solution, have been determined by single crystal X-ray crystallography.

The syntheses and the crystal structures of NH411LnIIIPMo11O392·16H2O LnIII Ce 1, Sm 2, Dy 3 or Lu 4 are reported in which an LnIIIcation is sandwiched between two ‘lacunary’ PMo11O397−anions to give a complex with eight oxygen atoms coordinated to the lanthanide centre in a twisted square antiprismatic geometry. This analogous series of complexes represents only the second time that the PMo11O397−anion has been fully crystallographically characterised. All four compounds are synthesised in high yield and characterised by a range of physical and spectroscopic techniques. 31P NMR, Raman and UVVisnIR spectroscopies give a clear indication that the LnIIIPMo11O39211−anion is also stable in solution. As LnIIIcontracts across the lanthanide series the Ln–O bond distances decrease and the splitting of the νP–Ovibrational mode within the PMo11O397−unit increases. The relative stability of this species in solution may have importance in elucidating the speciation of Lniii and Aniii cations in nuclear waste solutions where phosphopolymolybdate anions are known to form.