J.S. Casas

Main group metal complexes of semicarbazones and thiosemicarbazones. A structural review

Abstract The structural aspects of the complexes formed by thiosemicarbazones (TSCs) and semicarbazones (SCs) with the metallic elements of Groups 12, 13, 14 and 15 are surveyed up to 1998. Descriptions of 71 structures containing neutral or deprotonated TSCs and ten with SCs include information on the metal-to-ligand bonds and the coordination behaviour of the ligand. The survey shows that TSCs are very versatile coordination agents with these acceptors.

Diorganotin(IV) derivatives of salicylaldehydethiosemicarbazone. The crystal structure of dimethyl- and diphenyl- (salicylaldehydethiosemicarbazonato)tin(IV)

Abstract The title compounds have been prepared by reacting the corresponding diorganotin(IV) oxide with salicylaldehyde thiosemicarbazone (H2L). [SnMe2(L)] crystallizes in the monoclinic space group P21/n with a=9.480(3), b=13.532(7), c=10.541(3) A, β=100.33(2)° and Z=4 (R=0.0230, R′=0.0258). [SnPh2(L)] crystallizes in the space group P21/a with a=13.483(8), b=10.078(1), c=15.622(4) A, β=113.66(4)° and Z=4 (R=0.030, R′=0.031). Both complexes consist of molecules in which the bisdeprotonated ligand is O,N,S-bonded and the tin atom exhibits distorted pentacoordination, with small differences between the methyl and phenyl derivatives in bond distances, bond angles and intermolecular hydrogen bonds. The spectral properties of the complexes (IR, Mossbauer and 1H, 13C and 119Sn NMR spectra) are discussed in the light of this structural information.

Structural aspects of the coordination chemistry of organothallium(III) and organomercury(II) derivatives

Abstract This review surveys the main structural aspects of the coordination chemistry of mono-, di- and triorganothallium(III) and mono- and diorganomercury(II) complexes. It covers all organothallium(III) derivatives reported up to the end of 1997 and the organomercury compounds reported between 1993 and 1997. Structures are classified primarily by coordination number and secondarily by kernel complexity.

Synthesis and spectroscopic properties of diorganotin(IV) derivatives of 2,6-diacetylpyridine bis(thiosemicarbazone). Crystal structure of diphenyl{2,6-diacetylpyridine bis(thiosemicarbazonato)}tin(IV) bis(dimethylformamide) solvate

The reaction of the title ligand (H2DAPTSC) with SnR2O (R=Me, Ph) in DMF afforded the complexes [SnR2(DAPTSC)]. The phenyl derivative crystallizes as [SnPh2(DAPTSC)]·2DMF in the P21/n space group, with lattice constants: a=9.753(1), b=18.962(1), c=17.923(3) A, β=97.93(1), Z=4 and R=0.035. The molecular complex is pentagonal bipyramidal, with the five donor atoms of the ligand in the pentagonal plane and the two phenyl groups in the axial positions. A comparative study based on the spectral properties (IR, Mossbauer and 1H, 13C and 119Sn NMR spectroscopy) of the two complexes suggests a similar structure for [SnMe2(DAPTSC)].

Synthesis, structure, and spectroscopic properties of acetato (dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)tin(IV) acetic acid solvate, [SnMe2 (PyTSC)(OAc)].HOAc. Comparison of its biological activity with that of some structurally related diorganotin(IV) bis(thiosemicarbazonates)

The synthesis, X-ray structure, behavior in solution, and biological properties of the complex [SnMe2(PyTSC)(OAc)].HOAc (HPyTSC = pyridine-2-carbaldehydethiosemicarbazone) are reported. The tin atom of this complex is coordinated to an N,N,S-tridentate PyTSC- anion, to a monodentate acetate ion, and to the two methyl groups in an approximately pentagonal bipyramidal environment with a vacant equatorial position. The complex partially evolves in DMSO and in DMSO/CHxCl4-x (X = 1, 2) mixtures, giving HPyTSC and SnMe2(OAc)2. [SnMe2 (PyTSC)(OAc)].HOAc, [SnMe2(DAPTSC)], and [SnPh2(DAPTSC)].2DMF (H2DAPTSC = 2,6-diacetylpyridine bis(thiosemicarbazone)) all suppress proliferation of Friend erythroleukaemia cells (FLC). DMSO-induced differentiation of FLC is slightly suppressed by [SnMe2(DAPTSC)] and is unaffected by [SnPh2(DAPTSC)].2DMF and [SnMe2(PyTSC)(OAc)].HOAc.

Synthesis of [2-(pyridin-2′-yl)phenyl]-mercury(II) arylthiosemicarbazonates: An unusual coordination mode of a deprotonated 2-formyl-(2-hydroxy-benzene)-thiosemicarbazone

Abstract The reactions of [2-(pyridin-2′-yl)phenyl]mercury(II) acetate with 2-formyl-benzene-(Hbtsc), 2-formyl-(2-hydroxybenzene)-(H2stsc) and 2-formyl-(4-methoxybenzene)-(Hmbtsc) thiosemicarbazones in ethanol in 1:1 ratio at room temperature formed [Hg(C6H4C5H4N)L] (L=btsc, 1; Hstsc, 2; mbtsc, 3). The derivative [Hg(C6H4C5H4N)L] 2 crystallises in the triclinic space group P1 (n. 2), Z=2, R=0.0353 and V=906.8(3)A3. Mercury is bonded strongly only to sulphur atom of thiosemicarbazonate anion [Hg–S, 2,357(2)A] and Hg...N(3) distance of 3.126(6)A, slightly less than the sum of the van der Waals radii (3.28 A) shows a weak interaction. The pyridyl nitrogen binds strongly to Hg [Hg–N(4), 2.575(6)A] with a short C(9)HgN(4) bite angle of 74.6(2)°, but Hg retains near linearity in CPhHgS bond angle [177.8(2)°]. 1H and 19;Hg NMR spectra in CDCl3 solution reveal two isomers (A and B) for each of 1–3 and probably also a third isomer (C) for 2. The similarity of 1H and 19;Hg data of B isomers (minor for 1 and 3; major for 2) clearly support that thiosemicarbazones are unidentate S-donors as established for crystallized B isomer of 2 (major) by X-ray study, with pyridyl nitrogen of 2-pyridylphenyl coordinating to Hg. The A isomers (major for 1 and 3; minor for 2) have presumably N3,S-coordinated thiosemicarbazonates with weak Hg–N(pyridyl) interaction and the Hg atom formally tetracoordinated.

CRYSTAL STRUCTURE OF TRIPHENYL(5-MERCAPTO-1-PHENYL-1,2,3,4-TETRAZOLATO)TIN(IV)

Abstract The title compound was prepared from 1-phenyl-5-thione-1,2,3,4-tetrazole and triphenyltin(IV) hydroxide and its crystal structure was determined by X-ray diffraction. The lattice is formed by discrete molecules that contain the tin atom coordinated to three phenyl groups and to the tetrazole via the deprotonated -SH group in a distorted tetrahedral coordination polyhedron. There is evidence of a very weak intramolecular interaction between N(4) of the tetrazole and the Sn atom. 13C and 15N NMR studies (CDCl3) suggest that in solution the tetrazole is also in the deprotonated thiol form, and binds to the tin via its S atom.

The crystal structure of the salts [Hthiamine][SnMe2(H2O)Cl3]Cl and [Hthiamine][SnPh2Cl4]H2O: competition between water and chloride for coordination to diorganotin dihalides

Abstract Reaction of thiamine chloride hydrochloride (TCl·HCl) (vitamin B 1 hydrochloride) with SnMe 2 Cl 2 and SnPh 2 Cl 2 in 9:1 v/v ethanol-water afforded the salts (HT)[SnMe 2 (H 2 O)Cl 3 ]Cl ( I ) and (HT)[SnPh 2 Cl 4 ]H 2 O ( II ) respectively. Both compounds were characterized by mass spectrometry and by IR and Raman spectroscopy, and the crystal structures of both were determined by X-ray diffraction. I crystallizes in the monoclinic space group P 2 1 / n ; the thiaminium cation adopts the F conformation, and in the anion the tin atom co-ordinates to two trans C atoms of methyl groups, three Cl atoms and the O atom of a water molecule in a distorted octahedral arrangement. II crystallizes in the triclinic space group P 1 ; the thiaminium cation adopts the S conformation, and there are two kinds of [SnPh 2 Cl 4 ] 2− anion, one placed between two cations with its phenyl groups stacking over their pyridine rings, and the other without a close relationship with any cation. The two Sn atoms lie on a crystallographic inversion centre and have a separation of (0.5, 0.5, 0.0). Several hydrogen bonds are present in both structures, as well as S … O electrostatic interactions in II .

Organotin compounds with 2,2′-biimidazole derivatives. The crystal structure of dibromo(N,N′-dimethyl-2,2′-biimidazole)dimethyltin(IV)

The compounds [SnMe2Br2(DMBIm)], [(SnMe2X2)2(DMBIm)] and (NEt4)2[(SnMe2X3)2(DMBIm)] (X ue5fb Cl or Br; DMBIm = N,N′-dimethyl-2,2′-biimidazole) have been synthesized and characterized by conductivity measurements and IR and 1H NMR spectroscopy. The structure of dibromo(N,N′-dimethyl-2,2′-biimidazole)dimethyltin(IV) was determined by X-ray diffraction. Crystals are: orthorhombic, P212121, with a 9.402(2), b 10.389(3), c 16.228(3) A, V 1585 A3, Z = 4. The structure was refined to R = 0.047 based on 1461 observed intensities. The compound consists of discrete [SnMe2Br2(DMBIm)] molecules in which the tin atom is octahedrally six-coordinate with trans methyl groups and bidentate DMBIm. IR data for [(SnMe2X2)2(DMBIm)] complexes are consistent with coordination number 5, and those for (NEt4)2[(SnMe2X3)2(DMBIm)] with coordination number 6 for the tin atom. The 1H NMR spectra show that the compounds undergo extensive dissociation in CDCl3.

Synthesis and structural characterization of diphenldithiophosphinates of methyl- and phenylmercury(II). Crystal structure of MeHgS2PPh2

Abstract Methyl- and phenyl-mercury(II) derivatives of diphenyldithiophosphinic acid (HS 2 PPh 2 ) have been prepared. The structure of crystalline MeHgS 2 PPh 2 has been determined by X-ray diffraction and shown to consists of MeHgS 2 PPh 2 molecules in which the mercury atom is bound to the methyl group and to one sulphur atom of the ligand, with a further weak intermolecular interaction (secondary bond) with the other sulphur atom of a neighbouring ligand holding the molecules in pairs in the lattice. The spectroscopic properties of RHgS 2 PPh 2 (IR, Raman and 1 H, 13 C, 31 P and 119 Hg NMR) are discussed in the light of the X-ray results.