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The structure of the title compound has been solved from diffractometer data by direct methods and refined by least-squares techniques to R 0·082 for 1734 observed reflexions. Crystals are monoclinic, space group P21, with unit-cell dimensions a= 10·575(5), b= 8·985(5), c= 14·930(7)A, β= 115·9(2)°. The two aromatic rings are nearly parallel, the dihedral angle between their mean planes being 178·4°. A strong intermolecular hydrogen bond [O(5)⋯ O(6I) 2·52 A] joins tow molecules related by a 2I axis. The packing is mainly built from a three-dimensional network of hydrogen bonds, involving in particular the seven water molecules.

1,2-Bis(diphenylphosphoryl)ethane (dppoe) forms complexes with diorganotin(IV) chlorides of the type SnR2Cl2(dppoe)(R = Prn, Bun, or Ph), the i.r. and tin-119 Mossbauer spectra of which have been recorded. The crystal structure of SnBun2Cl2(dppoe) has been determined from single-crystal X-ray data collected by counter methods and refined by full-matrix least-squares techniques to R= 0.0461 for 2 430 observed reflections. Crystals are triclinic, space group P, with unit-cell dimensions a= 11.775(5), b= 15.987(7), c= 11.006(5)A, α= 102.12(5), β= 114.55(6), γ= 101.69(5)°, and Z= 2. Tin is bonded to two Cl– ions, to two C atoms and to two O atoms, to one more loosely than the other. The weaker co-ordination of one of the two OP groups is also reflected in distortions of the geometry of the co-ordination polyhedron. The structure is polymeric in that the dppoe ligand forms bridges between adjacent tin atoms. Tin-119 Mossbauer spectra have been recorded for the three SnR2Cl2(dppoe) complexes in the temperature range 77–150 K, and for the complex (SnPh3Cl)2(dppoe) at 77 K. Quadrupole-splitting data for the former are consistent with a trans-SnC2X4 arrangement about the tin atom in each case. Recoil-free fraction temperature coefficients, a, have also been determined for the three SnR2Cl2 complexes; root-mean-square amplitudes of vibration, 〈x〉, and absolute recoil-free fractions, ƒ, have been estimated at various temperatures for SnBun2Cl2(dppoe).

A series of MnII, CoII, NiII, CuII, and ZnII complexes with 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone)(H2dapab) has been prepared from the reaction of the hydrazone with metal chlorides and acetates. The i.r. spectra are reported and evaluated to obtain information on the co-ordinating behaviour of the hydrazone. An X-ray diffraction analysis carried out on [Mn(H2dapab)(CH3OH)Cl]Cl·H2O has shown it to possess pentagonal-bipyramidal geometry with the H2dapab ligand occupying the equatorial plane and the Cl and CH3OH groups at the axial sites. The structure has been refined to R= 0.0676 for 2173 observed diffractometer data.

The chelating behaviour of neutral and deprotonated 2,6-diacetylpyridine bis(benzoylhydrazone)(H2dapb) has been investigated in some new complexes of MnII, CoII, NiII, CuII, and ZnII. An X-ray diffraction analysis was carried out on [Mn(H2dapb)(OH2)Cl]Cl. The crystals are monoclinic, space group P21/c, with unit-cell dimensions a= 7.065(6), b=17.096(9), c=19.446(13)A, β= 96.89(8)°, and Z= 4. The structure was solved by the heavy-atom technique from 1 545 observed independent reflections recorded at room temperature on an automated diffractometer and refined to a final R value of 0.0329. The structure consists of [Mn(H2dapb)(OH2)Cl]+ cations and Cl– anions. The cation has a pentagonal-bipyramidal geometry, with H2dapb forming the equatorial plane and the H2O and Cl groups occupying the axial positions. The i.r. spectra suggest differences in the interaction of these metals with the hydrazone molecule.

Organotin(IV) complexes of formula SnR2Cl2(dppoet)[dppoet =cis-1,2-bis(diphenylphosphoryl)ethylene; R = Bun, Prn, or Ph] have been synthesised and characterised by i.r. and tin-119 Mossbauer spectroscopies. An X-ray diffraction analysis has been carried out on SnBun2Cl2(dppoet)(1) and SnPrn2Cl2(dppoet)(2). Both compounds crystallize in the monoclinic system with a= 13.76(1), b= 15.29(1), c= 18.36(1)A, β= 113.70(9)°, Z= 4, and space group P21/c for (1) and a= 11.362(4), b= 16.816(4), c= 9.324(3)A, β= 108.94(3)°, Z= 2, and space group P21, for (2). The structures have been determined using diffractometer data and refined to conventional R factors of 0.0979 for (1) and 0.0532 for (2)(3 113 and 2 233 reflections, respectively). The major difference between the two structures is associated with behaviour of the dppoet ligand, i.e. symmetrically bidentate in (1) and predominantly unidentate in (2). Tin-119 Mossbauer spectra have been recorded for both (1) and (2) in the temperature range 77–150 K. Quadrupole splitting values of ca. 4 mm s–1 are in accord with the trans-SnR2X4 geometry deduced from the X-ray studies, whilst the values of the temperature coefficients of the recoil-free fraction are characteristic of molecular lattices, the lower value for (2) being attributed to the more open co-ordination of the tin atom in this complex.

The structure of the title compound (I) has been solved from diffractometer data by the heavy-atom technique and refined by least-squares methods to R 0.043 for 1 513 observed reflections. Crystals are rhombohedral, with unitcell dimensions a= 13.54(1), c= 7.07(1)A. The structure consists of [Bi{(tu)1.5Cl1.5}Cl3]3/2–(tu = thiourea) anions, in which there is disorder involving thiourea and chlorine atoms, and [Bi(tu)6]3+ cations. In both ions bismuth atoms occupy special positions in space group P and bond octahedrally to thiourea and (or) chlorine ions. A detailed comparison between this compound and 3BiCl3·7tu is made.

Tetraphenyldibismuth, Bi2Ph4, is best prepared by the reaction of BiPh2I with 1 equivalent of sodium in liquid ammonia, followed by extraction with toluene and recrystallization from anhydrous ethanol. It is sensitive to air and slightly thermochromic. The crystal and molecular structure was solved by X-ray diffraction methods: triclinic, space group P, with a= 7.865(4), b= 11.444(5), c= 6.257(3)A, α= 105.24(4), β= 94.20(7), γ= 96.52(6)°, and Z= 1; R= 0.0560 for 1 097 absorption-corrected reflections having I 3σ(I). The molecule has a staggered trans conformation, with a bismuth–bismuth distance of 2.990(2)A. Tetraphenyldibismuth reacts promptly with di-iodine to give BiPh2I, and with p-benzoquinone, elemental sulphur, and diazomethane to give the corresponding products of bismuth(III) resulting from oxidative insertion into the bismuth–bismuth bond.

The crystal and molecular structure of the title compound has been determined by the heavy-atom method and refined by least-squares techniques on 1 639 independent X-ray diffractometer data to R 0.059. Crystals are orthorhombic, space group Pbca, with a= 29.76(4), b= 9.80(1), c= 19.95(3)A, and Z= 8. The structure consists of discrete monomeric units containing seven-co-ordinate tin in a pentagonal-bipyramidal geometry, the two nitrate groups and the triphenylphosphine oxide molecule being equatorial, with the two phenyl rings at the apices. One of the two rings is disordered between two crystal orientations.

2,6-Diacetylpyridine bis(salicyloylhydrazone)(H2daps) has been synthesized and its co-ordinating properties have been investigated in the complex [SnPrn2(daps)] by means of spectroscopic (i.r. and u.v.) and X-ray diffractometric techniques. Crystals of the compound are orthorhombic, with a= 18.332(10), b= 17.187(11), c= 9.161(5)A; Z= 4, space group P212121. A total of 1 936 observed reflections have been measured by single-crystal diffractometry and refined by full-matrix least squares to R 0.0402. The quinquedentate behaviour and the near planarity of the organic ligand favours a pentagonal-bipyramidal arrangement around tin with the two propyl groups occupying the axial sites.

The structure of the title compound was solved from X-ray diffractometer data by Patterson and Fourier methods and refined by least-squares techniques to R 5.9% for 2 166 independent reflections. Crystals are monoclinic, space group P21/c, with unit-cell dimensions: a= 9.993(5), b= 6.915(4), c= 13.593(6)A. β= 91.9(1)°, Z= 4. Co-ordination around tin can be described as tetrahedral and involves two adjacent NO3– anions and two organic molecules. There are two longer Sn-O contacts which complete the co-ordination to six. The nitrate group and the organic ligand both bridge two metal atoms in a rather unusual way, causing the structure to be polymeric.

Diastereoisomeric meso and rac forms of 1,2-bis(phenylsulphinyl)ethane (1) and (2) respectively, have been separated and treated with K2[PtCl4] to obtain the title complexes (3) and (4) respectively. The crystal structures of (1) and of the enantiomeric (S,S) form of (2), indicated as (2a), as well as of (3) and (4), have been solved by X-ray analysis from three-dimensional counter data and refined by block-diagonal least squares to R 0.028 and 0.051 for the ligands, and by full-matrix least squares to R 0.030 and 0.056 for the complexes, respectively. The co-ordination around platinum, which involves two chlorides and two sulphur atoms of the organic ligand, is quite close to square planar for (4) and only slightly tetrahedrally distorted for (3). The lengths of the Pt–Cl bonds are in fairly good agreement with those found in square-planar platinum(II) complexes, whereas the Pt–S bonds are slightly shorter. The different conformations assumed by the ligand when unco-ordinated or co-ordinated to the metal are compared and discussed. The structural data are related to i.r. and 1H n.m.r. measurements.

Tetraphenyldibismuthine, Bi2Ph4, was prepared by reducing BiPh2Cl with sodium in liquid ammonia and characterized by conventional methods, including X-ray diffractometry.

3-Chloro-1,2-benzisothiazole (I) reacts with diethyl malonate, in the presence of quaternary ammonium bases, under conditions of phase-transfer catalysis to give products such as, in the reaction with diethyl sodiomalonate, diethyl 1,2-benzisothiazol-3-ylmalonate (IV) and ethyl 1,2-benzisothiazol-3-ylacetate (V), formed by normal nucleophilic substitution at the 3-position, and diethyl (2-cyanophenylthio)malonate (II) and ethyl 3-aminobenzo[b]thiophen-2-carboxylate (III), produced by scission of the isothiazole ring. However, in one case the reaction, carried out according to Makosza, is more complex and mainly proceeds towards the 3-(3-aminobenzo[b]thiophen-2-yl)-1,2-benzisothiazole (VII), a product which was not previously identified and whose structure we have now established from chemical and spectral properties and X-ray crystal structure analysis. The structure of (VII) was determined from X-ray diffractometer data by direct methods and refined by least-squares to R 0.055 for 1 150 independent reflections.

By reaction of anhydrous cobalt(II) chloride with a secondary amine and carbon dioxide in a hydrocarbon solvent, NN-dialkylcarbamato-complexes of cobalt(II), [Con(O2CNR2)2n](R = Et or Pri), have been prepared. The crystal and molecular structure of the hexameric violet derivative, [Co6(O2CNEt2)12], has been solved by X-ray diffraction methods. The complex is monoclinic, space group C2/c, with a= 18.428(9), b= 19.189(8), c= 24.654(13)A, β= 95.90(6)°, Z= 8, and R= 0.0639. The six cobalt atoms are joined by bridging carbamato-groups. The main structural feature of the hexameric molecule is that four of the cobalt atoms are five-co-ordinated in a distorted trigonal bipyramidal geometry. The cobalt(II) complexes react with electrophiles with displacement of carbon dioxide.

The structure of the title compound has been solved from diffractometer data by the heavy-atom method and refined by least-squares techniques to R 8.24% for 890 independent reflections. Crystals are monoclinic, space group P21/n, with unit-cell dimensions: a= 8.894(6), b= 14.603(8), c= 7.476(6)A, β= 97.85(5)°, Z= 4. The structure consists of planar trigonal [HgCl3]– anions and pyramidal [Me3S]+ cations. Two chloride ions bridge consecutive [HgCl3]– anions, giving rise to infinite chains running along [001]. I.r. and Raman spectra between 3 500 and 50 cm–1 have been recorded and characteristic [Me3S]+ and [HgCl3]– frequencies assigned. The spectral features agree with the planar trigonal structure of the anion. Raman data and molecular-weight measure-ments showed that [HgCl3]– is strongly dissociated in aqueous solution.

Tetraphenyldibismuthane reacts with [Co2(CO)8] to give the product of oxidative addition, [Co(BiPh2)(CO)4], which was isolated as its triphenylphosphine adduct, [Co(BiPh2)(CO)3(PPh3)]. [Co(BiPh2)(CO)3(PPh3)] crystallises in the orthorhombic space group Pbca, with a= 26.105(13), b= 21.066(10), c= 10.845(3)A, Z= 8, R= 0.0522, and R′= 0.0497. The molecular structure consists of discrete [Co(BiPh2)(CO)3(PPh3)] units, the geometry around cobalt being that of a distorted trigonal bipyramid with three equatorial carbonyl groups and the BiPh2 and PPh3 ligands occupying the axial positions. The reactivity of [Co2(CO)8] towards E2Ph4 was compared along the series from E = arsenic to bismuth. Oxidative addition (E = Bi) and substitutive oxidative addition (E = As or Sb) reactivity patterns were encountered. No tendency of terminal BiPh2 to become bridging with CO substitution was observed. The unique behaviour of BiPh2 as a ligand is explained in terms of the low availability of the second lone pair on bismuth for bonding, in spite of the considerable σ-donation from bismuth to cobalt suggested for terminal BiPh2 by the i.r. spectra.

A new seven-co-ordinate manganese(II) complex [Mn(HL)(OH2)2Cl]Cl·H2O has been synthesised with 2,6-diacetylpyridine mono(2-aminobenzoylhydrazone)(HL) by using a template reaction, and characterised by X-ray crystallography. The structure has been solved using direct methods and Fourier-difference techniques and refined by least squares to R 0.0470 for 1 862 observed diffractometer data. The co-ordination around the manganese atom is a pentagonal bipyramid, with a water molecule and a chlorine atom in the axial positions and four donor atoms (two nitrogens and two oxygens) of HL and a second water molecule in the equatorial plane. The molecular packing involves an extensive network of hydrogen bonds.

The i.r., u.v., n.m.r., and mass spectra, and X-ray crystal structure analysis of the title compound are given. Crystals are orthorhombic, with a= 14.100(6), b= 12.461(7), c= 4.972(2)A, space group P212121, Z= 4. The structure was solved by the heavy-atom technique and refined by least-squares to R 0.051. The structural formula of the compound, assigned on the basis of the X-ray analysis, is helpful in devising syntheses of 3-substituted 1,2-benzisothiazoles

The co-ordinating properties of cis- and trans-1,2-bis(diphenylphosphoryl)ethylene (cdppoet and tdppoet respectively) have been examined in two new organotin(IV) complexes, SnPh2(NO3)2(cdppoet)·CHCl3(1) and [SnPh2(NO3)2]2(tdppoet)·2H2O (2), on both of which an X-ray diffraction analysis was carried out. Crystals of (1) are orthorhombic, space group Pbca, with a= 17.684(4), b= 38.773(9), c= 12.092(3)A, and c= 8. Crystals of (2) are triclinic, space group P, with a= 12.247(10),b= 12.263(11), c= 11.914(11)Aα= 99.13(7), β= 110.37(7), γ= 118.36(7)°, and Z= 1. Both structures were solved by the heavy-atom technique from diffractometer data and refined by least-squares methods to a conventional R factor of 0.0767 for (1) and 0.0344 for (2) on the basis of 2 053 and 3 655 observed reflections. The structure of both compounds closely approximates a pentagonal bipyramid about the tin atom with five O atoms in the basal plane and with two C atoms in the apical positions. The main differences between the two structures lie in the ligand behaviour of the dppoet molecule, namely bidentate chelating in (1) and bidentate bridging in (2).

The structure of the title compound was solved from diffractometer data by Patterson and Fourier methods and refined by least-squares techniques to R 5·0% for 2967 observed reflections. Crystals are triclinic, space group P, with unit-cell dimensions: a= 8·354(8), b= 8·304(7), c= 11·115(8)A, α= 108·2(1), β= 100·3(1)°, γ= 102·3(1)°, Z= 2. The co-ordination around mercury involves the diphenyl sulphoxide molecule via the oxygen atom at 2·58 A, two close chlorine atoms at 2·291 and 2·289 A, and two chlorine atoms at neighbouring molecules at 3·230 and 3·284 A. A sixth position is occupied by a phenyl ring at 3·51 A.