Homoleptic Zinc(II) Complexes with First and Second Coordination Shells of 5-tert-Butylpyrazole

Di-platinum complexes containing thiolato-urea ligands: structural and anion binding studies

The new di-platinum(II) thiolato-bridged complexes [(dppp)Pt{micro-S(CH(2))(n)NHC([double bond, length as m-dash]O)NHR}](2)(OTf)(2) (n = 2, 3; R = Et, Ph) have been synthesized. The X-ray crystal structures of three of these complexes have confirmed their formulation and highlighted the ability of the urea groups on the thiolato bridges to display hydrogen bonding interactions with anions. The binding of anions by these receptors has been quantitatively determined by (1)H NMR spectroscopy and in a qualitative fashion by indicator displacement assays. These studies have shown the receptors to be selective for inorganic phosphate. In addition we have isolated and structurally characterized an unusual 1D coordination polymer with formula {[(dppp)Pt{micro-S(CH(2))(2)NHC([double bond, length as m-dash]O)NHR}][Pb(2)Cl(6)]}(n). The X-ray crystal structure of this inorganic polymer has shown that it consists of units of the di-platinum-thiolato cations bridged by [Pb(2)Cl(6)](2-) moieties.

Pyrazoles and pyrazolides-flexible synthons in self-assembly

This Perspective summarises the chemistry of the pyrazole ring, and reviews the metal coordination modes adopted by 1H-pyrazoles and their anions. Pyrazolide anions are probably the most versatile ligands in coordination chemistry, with 20 different terminal or bridging coordination modes having been identified so far. Metal cluster compounds supported by pyrazolido ligation are surveyed, concentrating on those reported during the past ten years. Highlights include the wide structural diversity in apparently simple main group pyrazolides; luminescence and charge-transfer complexes in coinage metal pyrazolide clusters; the use of robust metal pyrazolide clusters to construct liquid crystals, supramolecular materials and metal-organic frameworks; and supramolecular complexes formed by pyrazolide-supported metallacrowns.

Four copper(ii) pyrazolido complexes derived from reactions of 3{5}-substituted pyrazoles with CuF2 or Cu(OH)2

Treatment of CuF(2) with 2 equiv of 3{5}-[pyrid-2-yl]pyrazole (Hpz(Py)), 3{5}-phenylpyrazole (Hpz(Ph)) or 3{5}-[4-fluorophenyl]pyrazole (Hpz(PhF)) in MeOH, followed by evaporation to dryness and recrystallisation of the solid residues, allows solvated crystals of [{Cu(micro-pz(Py))(pz(Py))}(2)] (1), [{Cu(micro-pz(Ph))(2)}(4)] (2) and [Cu(4)F(2)(micro(4)-F)(micro-pz(PhF))(5)(Hpz(PhF))(4)] (3) to be isolated in moderate-to-good yields. Similar reactions of these three pyrazoles with Cu(OH)(2) in refluxing MeOH respectively afford 1, 2 and [Cu(pz(PhF))(2)(Hpz(PhF))(2)] (4) in ca. 10% yield. Crystalline 1 x 1/2H(2)O x 2CHCl(3) contains two independent dinuclear molecules with a puckered di-(1,2-pyrazolido) bridge motif, linked by a bridging, hydrogen-bonding water molecule. Compound 2 x 1/2C(5)H(12), containing cyclic, square tetranuclear complex molecules, is the first homoleptic divalent metal pyrazolide to have a discrete molecular rather than polymeric structure, for a metal other than Pd or Pt. The two independent complex molecules in 3 x 3/4CH(2)Cl(2) x Hpz(PhF) contain a unique tetrahedral [Cu(4)(micro(4)-F)](7+) core, three of whose edges are spanned by bridging pyrazolido groups. Magnetic data show that the copper centres in 1 and 3 are antiferromagnetically coupled, but that dried bulk samples of 2 do not retain their molecular structure.