Edward R.T. Tiekink

Structural features of group V A xanthates. The crystal and molecular structures of tris(O-isopropylxanthatoarsenic(III), antimony(III) and -bismuth(II)

Abstract The crystal structures of the title compounds, M(S2COiC3H7)3, M = As(III), (1); Sb(III), (2); and Bi(III), (3) have been determined by three dimensional X-ray diffraction techniques and refined by a least square method. Crystals of (1) and (2) are isomorphous and both crystallize in the rhombohedral space group R 3 , with unit cell parameters for (1) ahex = 11.559(2), chex = 28.131(3) A and for (2) ahex = 11.696(2) and chex = 28.135(2) A, Z = 6. The central metal atom in both (1) and (2) is coordinated by three asymmetrically chelating xanthate ligands [AsS 2.305(2) and 2.978(2) A and SbS 2.508(1) and 3.006(1) A] which form a distorted octahedral environment consistent with the presence of a stereochemically active lone pair of electrons. Crystals of (3) are orthorhombic, space group Pnma, Z = 4 with dimensions a = 11.003(3), b = 20.833(4) and c = 9.428(2) A. The environment of the bismuth atom in (3) is seven coordinate and is comprised of six sulphur atoms, derived from three asymmetrically coordinating xanthate ligands, and a bridging sulphur atom from a neighbouring molecule which results in the formation a polymeric array. For (1) final R and RW 0.050 and 0.047 respectively for 936 reflections [I ⩾ 3σ(I); (2) R 0.040, Rw 0.040 for 1455 reflections I ⩾ 2σ(I)]; and (3) R 0.052, Rw 0.039 for 1796 reflections [I ⩾ 2σ(I).

The crystal and molecular structures of tris(O-ethylxanthato)-gallium(III) and indium(III)

Abstract The crystal structures of the title compounds, Ga(S 2 COEt) 3 ( 1 ) and In(S 2 COEt) 3 ( 2 ) have been determined by three dimensional X-ray diffraction methods. Both compounds crystallize in the trigonal space group R 3 - with Z = 6. Cell dimensions for ( 1 ) are a hex 15.065(1) and c hex 13.421(1) A and for ( 2 ) 15.319(3) and 13.522(4) A. Final R. and R w values 0.044 and 0.049 for ( 1 ) and 0.040 and 0.037 for ( 2 ) for 668 and 1153 statistically significant reflections respectively. The complexes are isostructural. The metal centres are in a distorted octahedral environment, the distortion arising from the restricted bite distance of the xanthate ligands. For each compound, each xanthate moiety chelates the metal atom with similar M-S bonds.

The preparation and characterization of mixed dithiolate ligand complexes: the crystal and molecular structure of (O-ethylxanthato)(N,N′-diethyldithio-carbamato)tellurium(II)

The preparation and spectroscopic characterization of a number of mixed ligand complexes involving both xanthate and dithiocarbamate ligands are reported for the main group elements Sn(IV), Sb(III), Bi(III), and Te(II). The crystal structure of Te(exa)-(dedtc) shows that the tellurium atom is in a trapezoidal planar environment and that the dithiocarbamate ligand is more tightly bound than the xanthate ligand. Crystals of Te(exa)(dedtc) are monoclinic, P 2 1 / n , a = 8.942(2), b = 7.365(2), c = 22.415(5) A, and β = 92.68(2)°, with Z = 4. The structure was refined by a least squares method with final R = 0.042 and R w = 0.045 for 1593 reflections with I ⩾ 2σ( I ).

The preparation, spectral studies, and the crystal structure of dimethylbis(O-ethylxanthato)tin(IV)

Tin-119 NMR data indicate that the tin atom in (CH 3 ) 2 Sn(S 2 COC 2 H 5 ) 2 is four co-ordinated in dichloromethane solution. However, single crystal X-ray analysis shows the tin atom to be six co-ordinated in the solid state in which the bidentate xanthate ligands display gross asymmetry in their mode of co-ordination to the tin. The crystals are molecular and there is no association between neighbouring molecules. The unit cell of Me 2 Sn(exa) 2 is orthorhombic, Pnma, a = 14.165(1), b = 7.675(9), c = 13.977(2) A with Z = 4. The structure was refined by conventional least squares methods with final R 0.041 and R w 0.043 for 1229 unique reflections with 1 ⩾ 2σ(I).

The crystal and molecular structure of O-ethylxanthato-bis(quinolin-8-olato)-antimony(III) and a redetermination for tris(O-ethylxanthato)antimony(III)

Abstract The crystal structures of the title compounds Sb(C9H6NO)2(S2COC2H5) (1) and Sb(S2COC2H5)3 (2) have been determined by three dimensional X-ray diffraction techniques and refined by a least squares method; final R 0.049 for 2911 reflections [I ⩾ 3σ(I)] for (1) and R 0.047, Rw 0.046 for 846 reflections [I ⩾ 2σ(I)] for (2). Crystals of (1) are triclinic, space group P1, a = 10.825(2), b = 11.131(2), c = 8.911(1) A, α = 109.45(1), β = 95.92(1) and γ = 93.02(1)° with Z = 2. Crystals of (2) are rhombohedral, space group R 3 , arhomb = 10.138(3) A and α = 103.43(2)°. The environment of the Sb atom in (1) is based on a pentagonal bipyramidal geometry consisting of the six donor atoms of the three chelating ligands and a stereochemically active lone-pair of electrons which occupies the remaining axial position. The xanthate ligand chelates the Sb atom almost symmetrically with two long SbS bonds of 3.059(2) and 3.171(2) A. In contrast the xanthate ligands in (2) chelate the Sb atom with asymmetric SbS bonds of 2.511(2) and 3.002(3) A.

Haloxanthates of antimony(III) and bismuth(III): Crystal structure of Sb(S2COEt)2Br

Abstract The complexes Sb(S2COEt)2X (X = Cl, Br, I) and Bi(S2COEt)2X (X = Cl, Br) have been isolated as cystalline compounds. From infrared spectra and molecular weight determinations it is concluded that they are polymeric in the solid state but dissociate in solution. An X-ray structure determination of Sb(S2COEt)2Br shows that the antimony atom is six coordinate, with the bromine atoms forming bridges between pairs of antimony atoms leading to a zigzag chain. The unit cell is monoclinic, space group P21/c, with a = 10.769(2), b = 16.462(2), c = 8.360(2) A, and β = 110.71(2)°.

Tin-119 NMR studies of alkyl and aryl haloxanthates of tin(IV): The crystal and molecular structure of diphenyl(O-isopropylxanthato)chlorotin(IV)

Tin-119 NMR data are reported for the two series of compounds of the type R2Sn(S2COR′)2 and R2SnX(S2COR′) [where R = CH3, C6H5, R′ = C2H5, i-C3H7, and X = Cl, Br]. In solution both types of compounds appear to have a coordination number less than six. The crystal structure of o2SnCl(S2CO-i-C3H7) shows that the tin atom is penta-coordinated in a distorted trigonal bipyramidal environment. The iprxa ligand coordinates the tin atom with asymmetric SnS bonds of 2.450(2) and 2.826(1) A. The unit cell of o2SnCl(S2CO-i-C3H7) is monoclinic, P21/c, a = 12.206(4), b = 10.825(3), c = 19.374(3) A and β = 133.32(2)°, Z = 4. The structure was refined by conventional least squares methods with final values of R 0.038 and Rw 0.042 for 3112 unique reflections.