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The compounds [M(O2CNR2)4](M = Ti, Zr or Hf; R = Et or Pri) have been prepared by treating the corresponding metal tetrachloride with CO2–NHR2 in toluene. The structure of [Hf(O2CNPri2)4] has been solved by X-ray diffraction methods. Crystal data: monoclinic, space group P21/c, a= 12.756(3), b= 22.131(9), c= 14.548(5)A, β= 113.03(2)° and Z= 4. It consists of monomeric units, the hafnium atom being surrounded by the eight oxygen atoms of the four N,N-diisopropylcarbamato groups in a slightly distorted dodecahedral arrangement. By reaction with anhydrous hydrogen halides HX (X = Cl, Br or I) the hexahalogenometalate(IV) anions, [MX6]2–, as the diethylammonium derivatives, have been obtained in high yields. The redox reaction between [Ti(O2CNEt2)4] and [V(η-C5Me5)2] gives the titanium(III) and vanadium(III) complexes [{Ti(O2CNEt2)3}n] and [V(η-C5Me5)2(O2CNEt2)], respectively.

The complex [Sn(2-C6H4NNPh)(Ph)Cl2](1) can be prepared by treating [Sn(Ph)Cl3] with [Hg-(2-C6H4NNPh)2](1:1). The reactions of (1) with NMe4Cl (1 : 1) or excess of KX salts give NMe4[Sn(2-C6H4NNPh)(Ph)Cl3](2) or [Sn(2-C6H4NNPh)(Ph)X2][X = Br (3) or l(4)], respectively. The molecular structure of complex (1) shows a distorted trigonal bipyramidal coordination around the tin atom. The equatorial positions are occupied by both carbon atoms of the aryl ligands and by one of the chloro ligands. The angles in the equatorial plane differ from the 120° ideal value [C–Sn–C 136.2(2)°, Cl-Sn-C 111.4(2) and 106.0(1)°] with the tin atom lying 0.314 A out of the equatorial plane on the side of the axial Cl atom. The 2-(phenylazo) phenyl ligand forms with the tin atom a five-membered ring with a bite angle C–Sn–N of 70.9(2)°. The Cl–Sn bond distances are normal although the axial [2.415(2)A] is longer than the equatorial one [2.351(2)A]. Both C-Sn bond lengths are also normal and similar [2.114(5) and 2.117(5)A]. The N–Sn bond length [2.541(3)A] is longer than others reported. To our knowledge, this is the first mixed diaryltin(IV) complex structurally characterized.

Cyanometallates [N(PPh3)2][Ag(CN)2]1 and [N(PPh3)2]2[Pd(CN)4]2 reacted with SnPh3Cl, producing anionic complexes characterized by IR and 119Sn NMR spectroscopy, an X-ray structural analysis of the silver complex evidencing a Sn–NC–Ag bridging interaction; the crystal structure of 1 has also been determined for comparison.

Three compounds previously described as tin derivatives have been reinvestigated by X-ray diffraction and found to have the following formulae: Ag(AsPh3)(NO3)(1)[monoclinic, space group P21/c, a= 10.405(5), b= 18.895(12), c= 9.138(6)A, β= 98.35(8)°, Z= 4; R= 0.0450 for 2 036 reflections]; Ag(AsPh3)2(NO3)(2)[triclinic, space group P, a= 11.97(1), b= 12.02(1), c= 13.68(1)A, α= 102.0(1), β= 113.3(1), γ= 104.0(1)°, Z= 2; R= 0.0468 for 4409 reflections]; Ag(AsPh3)3(NO3)(3)[monoclinic, space group P21/n, a= 19.193(8), b= 14.003(7), c= 17.893(7)A, β= 96.4(1)°, Z= 4; R= 0.0478 for 3 543 reflections]. In all these compounds the silver atom is co-ordinated, in an irregular fashion, by arsenic and oxygen atoms. In addition, two new silver–tin complex salts have been prepared and structurally characterized by X-ray diffraction: [Ag(AsPh3)4][SnPh2(NO3)3](4)[triclinic, space group P, a= 22.57(2), b= 14.22(1), c= 14.07(1)A, α= 90.9(1), β= 69.9(1), γ= 65.6(1)°, Z= 2; R= 0.0635 for 4 494 reflections] and [Ag(AsPh3)4][SnPh2(NO3)2Cl](5)[triclinic, space group P, a= 22.68(2), b= 14.24(1), c= 14.24(1)A, α= 90.66(6), β= 69.17(5), γ= 64.36(4)°, Z= 2; R= 0.0648 for 7 108 reflections]. These two compounds are isostructural and contain a tetrahedral [Ag(AsPh3)4]+ cation and a bipyramidal anion in which the tin atom is co-ordinated apically by two phenyl groups; the equatorial sites are occupied by six oxygen atoms from three NO3– ions in (4), and by four oxygen atoms from two NO3– ions and a chlorine in (5).

The title compound has been shown by X-ray diffraction methods to be a centrosymmetric phenoxo-bridged dimer with terminal phenoxo- and ethylenediamine groups and hydrogen-bonded phenol molecules. The crystals are monoclinic, space group P21/n, and the unit cell has dimensions a= 19.000(13), b= 10.930(9), c= 8.968(5)A, β= 89.90(2)°, U= 1 862.4 A3, and Z= 4. The structure was refined by three-dimensional Patterson and Fourier techniques up to a conventional R value of 0.0437. The copper atoms are five-co-ordinate and the co-ordination geometry is that of a distorted square pyramid. The Cu ⋯ Cu distance is 3.215 A. The compound has a nearly normal magnetic moment at room temperature and the results of the present investigation are discussed in connection with the known magnetic and structural data for dimeric oxygen-bridged copper(II) complexes.

The synthesis and the i.r, and 119Sn Mossbauer spectroscopic characterization of SnEt2(dapt), SnBuCl(dapt)[H2dapt = 2,6-diacetylpyridine bis(2-thenoylhydrazone)], and SnBu2(daps)[H2daps = 2,6-diacetylpyridine bis(salicyloylhydrazone)] are reported together with the X-ray crystal structure of the first compound. The structure consists of monomeric units in which the tin atom exhibits a nearly pentagonal-bipyramidal co-ordination geometry with the equatorial plane defined by the N3O2 donor set of the hydrazone ligand and the two ethyl groups in the apical positions. Some disorder occurs in both the thienyl moieties.

The structure of the title compound has been solved from X-ray diffractometer data by the heavy-atom method and refined by least-squares techniques to R 0.060 for 4 409 independent reflections. Crystals are triclinic, space group P, with unit-cell dimensions: a= 11.29(1), b= 12.02(1), c= 13.68(1)A, α= 102.0(1), β= 113.3(1), γ= 104.0(1)°, and Z= 2. The structure consists of molecules of formula [{SnII(NO3)(AsPh3)(SnIVPh3)}2] in which SnII is five-co-ordinate in a highly irregular way by two adjacent [NO3]– anions and by the two triphenyl-metal groups, where a disordered distribution involving Sn and As is present. The nitrate groups bridge the two SnII atoms in the dimer in a rather unusual way.

Three new silver–tin complex salts with bis(diphenylarsino)methane (dpam) and bis(diphenylphosphino)methane (dppm) have been synthesized. The i.r. and 31P and 119Sn n.m.r. spectra as well as the conductivity data are reported and discussed together with the X-ray crystal structure of one of them, namely [Ag3Cl2(dppm)3][SnPh2(NO3)2Cl]·CH3OH. The trinuclear silver complex contains bridging chlorine and dppm ligands. All the three independent silver atoms are four-co-ordinated in a distorted tetrahedral configuration involving two chlorine and two phosphorus atoms. The co-ordination polyhedron about tin can be described as a distorted pentagonal bipyramid, having a chlorine atom and four nitrate oxygen atoms in the equatorial plane and two phenyl carbons at the apices.

Some new metal complexes of 2,6-diacetylpyridine bis(salicyloylhydrazone)(H2daps) have been prepared from the reaction of the hydrazone with Co, Ni, Cu, Zn, and Cd chlorides and acetates. The chelating behaviour of the hydrazone has been spectroscopically investigated in all compounds by means of i.r. and 1H n.m.r. techniques. The complex [Cd(H2daps)Cl2]·CHCl3·CH3OH has been subject to an X-ray analysis which established a seven-co-ordinate pentagonal-bipyramidal metal environment, with two axial Cl atoms and the H2daps ligand forming the basal plane.

Some new complexes of CoII, NiII, CuII, and ZnII with 2,6-diacetylpyridine bis(2-thenoylhydrazone)(H2dapt) have been synthesized and examined by i.r. Spectroscopy. The structure of Zn2(dapt)2 has been established by X-ray diffraction. Crystals are monoclinic, space group C2/c, with unit-cell dimensions a= 20.780(3), b= 17.162(2), c= 15.173(1)A,β= 48.85(1)°, and Z= 4. The structure has been solved by the heavy-atom method and refined by full-matrix least-squares calculations to R= 0.0587 for 2119 diffractometer data. The compound is dimeric with the pyridine ring unusually bridging two zinc atoms, which have a highly distorted octahedral co-ordination. The deprotonated ligand is not planar, the hydrazone side chains being considerably twisted out of the plane of the pyridine ring.

The structure of the title compound was solved from diffractometer data by the heavy-atom method and refined by least-squares techniques to R 0.109 for 1 134 observed reflections. Crystals are monoclinic, space group P21/c, with unit-cell dimensions: a= 20.710(10), b= 8.113(3), c= 8.090(4)A, β= 94.74(5)°, and Z= 4. A distorted tetragonal-pyramidal co-ordination around the mercury atom involves the di-n-butyl sulphoxide molecule at the apex via the oxygen atom at 2.59 A, two close chlorine atoms at 2.35 and 2.33 A, and two chlorine atoms from neighbouring molecules at 3.13 and 3.16 A at the base. The structural parameters of the title compound and of similar adducts have been correlated with their vibrational frequencies.

The crystal and molecular structure of (–)589[(S)s(S)c-Me(EtCHPhCH2)S·HgCl2]2 has been determined by the heavy-atom method from three-dimensional X-ray data collected by counter methods and refined by least-squares techniques to R 0.0468 for 1 207 observed reflections. Crystals are monoclinic, space group P21, with two molecules in a unit cell of dimensions a= 8.457(3), b= 5.634(3), c= 14.667(6)A, and β= 94.68(4)°. The S atom of the donor molecule and the non-bridging Cl(1) atom are strongly bonded to Hg [2.433(4) and 2.315(5)A, respectively]. The overall co-ordination sphere of Hg also includes three crystallographically equivalent bridging Cl(2) atoms [2.677(5), 2.838(10), and 2.995(10)A], and a very weakly π-bonded Ph ring (3.64 A), thus completing an approximately octahedral array. The triply bridging action of Cl(2) leads to the formation of a polymeric structure in which the molecules are linked in chains and further into ribbons parallel to the b axis. l.r. spectroscopic data are consistent with a bent Cl–Hg–Cl moiety. The absolute configuration at both chiral centres of the diastereoisomer is S. The (S)s absolute configuration at the sulphur atom has been correlated with the negative Cotton effect assigned to a charge-trasfer transition at 265 nm in the circular dichroism spectrum. The diastereoselective synthesis of the complex has been confirmed.

The co-ordinating properties of 2,6-diacetylpyridine bis(picolinoylhydrazone)(H2dappc) have been investigated in some new complexes of MnII, CoII, NiII, and ZnII characterized by spectroscopic and magnetic techniques. An X-ray diffraction analysis was carried out on Mn(dappc)·9H2O. The crystals are monoclinic, space group C2/c, with unit-cell dimensions a= 13.96(1), b= 15.25(2), c= 13.59(1)A, β= 109.59(8)°, and Z= 4. A total of 1 161 observed reflections have been measured by single-crystal diffractometry and refined by full-matrix least squares to R= 0.050. The manganese ion is in a pentagonal-bipyramidal environment with the dappc ligand occupying the pentagonal girdle and two water molecules in the axial sites.

The title compound has been synthesised and its spectroscopic properties and X-ray structure have been studied. The structure was refined by least-squares techniques to R 4·5% for 3083 independent reflections. Crystals are triclinic, space group P, with unit-cell dimensions: a= 13·334(7), b= 11·860(6), c= 9·424(6)A, α= 51·3(2), β= 77·5(2), γ= 71·7(2)°, Z= 1, (C19H24NO6SSn)2. The co-ordination around tin(IV) is pentagonal bipyramidal, the nitrate and oxalate anions and the sulphoxide molecule being equatorial, with the two phenyl rings at the apices. The oxalate ion acts as a centrosymmetric bridge between two co-ordination polyhedra. Some disorder occurs in the sulphoxide molecule, which occupies two positions around the O–Sn bond.

The crystal structure of the title compound (SnPh3Cl)2[Ph2As(O)CH2CH2(O)AsPh2] has been determined by X-ray diffraction. About tin, the geometry is essentially trigonal bipyramidal, the chloride ion and the diarsine ligand occupying the axial positions, with the aromatic rings in the equatorial plane.

The crystal structure of the title compound [SnPh2(NO3)(AsPh3O)]2(C2O4) has been determined by X-ray diffraction. The co-ordination geometry of the tin atom is a slightly distorted pentagonal bipyramid, the two phenyl rings occupying the axial positions, with the nitrate and oxalate ions and the triphenylarsine oxide in the equatorial plane. The compound exhibits a binuclear structure with the oxalate ion acting as centrosymmetric bridge between two co-ordination polyhedra.