Organotin biocides. X. Synthesis,structure and biocidal activity of organotin derivatives of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 2-mercaptobenzimidazole

Ten organotin derivatives of 2-mercaptobenzothiazole (Hmbt), 2-mercaptobenzoxazole (Hmbo) and 2-mercaptobenzimidazole (Hmbi) have been synthesised and thier structures characterised by spectroscopic methods. Triorganotin derivatives are all S-bonded to the ligand and four-coordinate at tin except Bu₃Sn(mbo) which is five-coordinate trans-ONSnR₃ polymer at 78K. The crystal structure of Cy₃Sn(mbt) has been determined and confirms the tetrahedral geometry at tin. Bu₂Sn(mbt)₂ is weakly six-coordinate by N,S chelating ligands. Biocidal activity patterns are presented for Cy₃Sn(mbt), Ph₃Sn(mbt) and Ph₃Sn(mbo).     

Structural chemistry of organotin carboxylates XV. Diorganostannate esters of dicyclohexylammonium hydrogen oxalate. Synthesis,crystal structure and in vitro antitumour activity of bis(dicyclohexyl-ammonium) bisoxalatodi-n-butylstannate and bis(dicyclohexylammonium) μ-oxalatobis(aquadi-n-butyloxalatostannate)

Dicyclohexylamine, oxalic acid dihydrate and di-n-butyltin oxide were reacted in 2:2:1 or 2:3:2 stoichiometries in ethanol solution to yield, respectively bis(dicyclohexylammonium) bisoxalatodi-n-butylstannate (1) and bis(dicyclohexylammonium) μ-oxalatobis(aquadi-n-butyloxalatostannate) (2); the hydrate was also obtained upon recrystallization of 1 from moist acetonitrile solution. The crystal structures of the two ammonium stannates have been determined at room temperature. In 1, the tin atom in the dianion exists in a skewtrapezoidal bipyramidal geometry with the basal plane being defined by two bidentate oxalate ligands; each ligand forms asymmetric Sn? O bonds [Sn? O 2.348(4), 2.110(4) Å and 2.112(4), 2.363(4) Å]. The apical sites are occupied by the two organo groups disposed over the weaker Sn? O bonds. In 2, the two tin centres of the dianion are connected via a tetradentate oxalate ligand situated about a centre of inversion and each tin atom exists in a pentagonal bipyramidal geometry. The pentagonal plane is defined by four oxygen atoms, two from the central ligand [Sn? O 2.282(4), 2.473(4)Å] and two from a ‘terminal’ oxalate ligand [Sn? O 2.239(4), 2.210(4)Å], and the fifth site is occupied by a water molecule of crystallization [Sn? O 2.422(4)Å]; the apical sites are filled by the n-butyl groups. Both compounds feature extended hydrogen-bonded networks involving the oxygen atoms of the dianion and the N-bound hydrogen atoms. Crystals of 1 are monoclinic, space group P2₁/n, with cell dimensions a = 13.408(3), b = 22.461(4), c = 13.996(2)Å, β = 100.97(2)^°; full-matrix least-squares refinement on 3305 reflections with I≥2.5σ(I) converged to R = 0.042 and R_w = 0.046. Crystals of 2 are monoclinic, space group P2₁/n, a = 13.729(3), b = 14.694(2), c = 14.889(2)Å, β = 104.83(2)^º; refinement on 2093 reflections converged to R = 0.030 and R_w = 0.031. The two di-n-butylstannates were screened in vitro against the mammary MCF-7 and WiDr colon carcinoma cell lines, and were found to be as active as cisplatin, a clinically used antineoplastic drug.     

o-Cyclohexadiamine complexes of some diorganotin,mono-organtotin and stannic carboxylates: Synthesis and spectral properties

o-Cyclohexadiamine (the base component of tetraplatin) adducts of Ph₂Sn(OCOCH₃)₂, nBu₂Sn(OCOH₃)₂, (PhCH₂)₂Sn(OCOCH₃)₂, PhSn(OCOCF₃)₃, BuSn(OCOCH₃)₃ and Sn(OCOCH₃)₄ have been synthesized and characterized by elemental analysis and spectroscopy. The compounds appear to be the first such adducts in their class.     

Fifty Years of Mössbauer Spectroscopy in Solid State Research – Remarkable Achievements,Future Perspectives

Mössbauer spectroscopy was founded more than fifty years ago based on an outstanding discovery by the young German physicist Rudolf Ludwig Mössbauer while working on his Ph.D. thesis. He discovered the recoilless nuclear resonance fluorescence of gamma radiation and was awarded the Nobel Prize in Physics in 1961 as one of the youngest recipients of this most prestigious award. His discovery led to the development of a new technique for measurements of hyperfine interactions between nuclear moments and electromagnetic fields. This method, with highest sharpness of tuning of 10^–13, yields information on valence state, symmetry, magnetic behavior, phase transition, lattice dynamics and other solid state properties.     

Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid-state and solution-phase characterization

Protoporphyrin IX (H₄PPIX) complexes of diorganotin(IV)chloro moieties with formula (R₂SnCl)₂H₂PPIX (R?Me, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H₄PPIX to R₂Sn(IV)Cl moieties, with bridging carboxylate (COO^?) has been inferred by comparison of the free and coordinated H₄PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R₂ trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model formalism. Fanally, the solution-phase spectral features of (R₂SnCl)₂^?H₂PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.     

Mossbauer Study of the Effect of Intraligand Substituents on the Spin Crossover in Solid (Dithiocyanato)BIS(N-Substituted-Phenyl-2-Pyridinaldimine) Iron (II)

The spin transition of high-spin (^sT₂?)low-spin (¹A₁) of (dithiocyanato) (N-phenyl-2-pyridinaldimine) iron (II) complexes can be altered by substituents on the phenyl ring. Mössbauer spectra at 78K for the 4-substituted derivatives (with the exception of the 4-OH-substituted derivative) indicate that the fraction of low-spin states increases with decreasing substituent electron-withdrawing ability, as measured by the Hammet σ constant (4-OCH₃<4-CH₃CONH 4-C₆H₅<4-CH₃<4-H<4-Cl<4-NO₂). In addition, the effect of methyl-substitution at the ortho-, meta- or paraposition of the phenyl ring on the spin transition was examined. Mössbauer spectra of these methyl-substituted complexes reveal quite different spin equilibria.     

Synthesis,spectroscopic characterization and in vitro antitumour activity of di-n-butyltin and diethyltin trimethoxybenzoates: X-ray structure analysis of bis[di-n-butyl(3,4,5-trimethoxybenzoato)tin] oxide

Di-n-butyltin(IV) and diethyltin(IV) 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates [(CH₃O)₃C₆H₂COO]₂SnR [Type a] and {[(CH₃O)₃C₆H₂COO]R₂Sn}₂O [Type b] have been synthesized and characterized spectroscopically. The crystal structure of bis[di-n-butyl(3,4,5- trimethoxybenzoato)tin] oxide has been determined. The triclinic unit cell contains one centrosymmetric dimer; a = 15.919(2) Å, b = 11.711(3) Å, c = 13.475(1) Å, and α = 63.63(2)°, β = 67.49(1)°, γ = 76.61(2)°. The geometry of the dimer is very similar to that of bis[di-n-butyl(5-methoxysalicylatotin] oxide), with two different types of five-coordinate tin atoms and one central planar Sn₂O₂ ring.     

Mössbauer Spectroscopic Studies of Ferrocenylaldimines and their TCNQ Complexes

A series of ferrocenylaldimines (Fc-CH=N-R) has been prepared by Schiff base condensation of formylferrocene with polyacenylamines RNH₂ where R = naphthyl, 5,6,7,8-tetrahydronaphthyl, anthracenyl, and pyrenyl groups. This step was followed by oxidation with TCNQ to give [Fc-CH = N-R][TCNQ]² salts. The electronic state of iron in these compounds was investigated by means of⁵⁷Fe Mössbauer spectroscopy.     

Mössbauer Spectroscopic Studies of Supported α-Fe2O3 and Fe Catalysts II: The Effect of the Second Metal Addition

The effect of the addition of a second metals such as Zn and Ni on the calcinaton and reduction of alumina, magnesia and silicasupported iron catalysis with total iron loading of 5wt% is investigated by Mössbauer spectroscopy. It is shown that the reducibility of supported α-Fe₂O₃ is gradually increased by adding the second metal. The values of the magnetic hyperfine field obtained from Mössbauer spectra for the Zn or Ni-added α-Fe₂O₃ or Fe catalysts decreased with increasing second metal loading.