New discrete and polymeric supramolecular architectures derived from dinuclear Co(ii), Ni(ii) and Cu(ii) complexes of aryl-linked bis-β-diketonato ligands and nitrogen bases: synthetic, structural and high pressure studies

New examples of nitrogen base adducts of dinuclear Co(II), Ni(II) and Cu(II) complexes of the doubly deprotonated forms of 1,3-aryl linked bis-beta-diketones of type [RC(=O)CH(2)C(=O)C(6)H(4)C(=O)CH(2)C(=O)R] (L(1)H(2)) incorporating the mono- and difunctional amine bases pyridine (Py), 4-ethylpyridine (EtPy), piperidine (pipi), 1,4-piperazine (pip), N-methylmorpholine (mmorph), 1,4-dimethylpiperazine (dmpip) and N,N,N',N'-tetramethylethylenediamine (tmen) have been synthesised by reaction of the previously reported [Cu(2)(L(1))(2)].2.5THF (R = Me), [Cu(2)(L(1))(2)(THF)(2)] (R = t-Bu), [Ni(2)(L(1))(2)(Py)(4)] (R = t-Bu) and [Co(2)(L(1))(2)(Py)(4)] (R = t-Bu) complexes with individual bases of the above type. Comparative X-ray structural studies involving all ten base adduct derivatives have been obtained and reveal a range of interesting discrete and polymeric molecular architectures. The respective products have the following stoichiometries: [Cu(2)(L(1))(2)(Py)(2)].Py (R = Me), [Cu(2)(L(1))(2)(EtPy)(2)].2EtPy (R = t-Bu), [Cu(2)(L(1))(2)(pipi)(2)].2pipi (R = t-Bu), [Cu(2)(L(1))(2)(mmorph)(2)] (R = t-Bu), [Cu(2)(L(1))(2)(tmen)(2)] (R = t-Bu) and {[Cu(2)(L(1))(2)(pip)].pip.2THF}(n), [Co(2)(L(1))(2)(tmen)(2)] (R = t-Bu), [Ni(2)(L(1))(2)(Py)(4)].dmpip (R = t-Bu), [Ni(2)(L(1))(2)(pipi)(4)].pipi (R = t-Bu) and [Ni(2)(L(1))(2)(tmen)(2)] (R = t-Bu). The effect of pressure on the X-ray structure of [Cu(2)(L(1))(2)(mmorph)(2)] has been investigated. An increase in pressure from ambient to 9.1 kbar resulted in modest changes to the unit cell parameters as well as a corresponding decrease of 6.7 percent in the unit cell volume. While a small 'shearing' motion occurs between adjacent molecular units throughout the lattice, no existing bonds are broken or new bonds formed.