Alan J. Crowe

Investigations into the antitumour activity of organotin compounds. I. Diorganotin dihalide and di-pseudohalide complexes

The antitumor activity of a series of diorganotin dihalide and di-pseudohalide complexes, R2SnX2, L2, where R = Methyl (Me), Ethyl (Et), n-Propyl (Pr), n-Butyl (Bu) or Phenyl (Ph); X = F, Cl, Br, I or NCS; and L = O- or N- donor organic ligand, which were modelled on the active platinum complexes, has been investigated. A number of these derivatives exhibit reproducible therapeutic activity in vivo towards P-388 lymphocytic leukaemia in mice, particularly the diethyltin dihalide and dipseudohalide complexes. The possible factors influencing activity are discussed, both in terms of the stereochemistry of the dialkyltin compounds and their structural similarity to the platinum antitumour drugs.

Investigations into the antitumour activity of organotin compounds. 2. Diorganotin dihalide and dipseudohalide complexes

Abstract The results of screening tests on 115 of the titled compounds against P388 lymphocytic leukaemia are reported and structure/activity relationships discussed.

Possible pre-dissociation of diorganotin dihalide complexes: relationship between antitumour activity and structure.

An examination of crystallographic data has indicated that the structure/activity relationship for diorganotin dihalide complexes is different from that of other metal dihalides, in that the Sn-N bond lengths appear to determine the antitumour activity.

The synthesis and tin-119m mössbauer spectra of some diorganotin dihalide and dipseudohalide complexes with nitrogen- and oxygen-donor ligands

Abstract The synthesis and 119m Sn Mossbauer spectra of 114 complexes of the type R 2 SnX 2 , L 2 (R  Me, Et, n-Pr, n-Bu, n-Oct, Ph, Bz; X  F, Cl, Br, I, NCS; L 2  2 monodentate or 1 bidentate O- or N-donor ligand(s)), 74 of which are new, are reported. The majority of the complexes are isostructural, having an octahedral trans -R 2 SnX 4 geometry about tin, whilst five of the diphenyltin complexes (R  Ph; X  Cl; L 2  AMP, Nphen; X  NCS; L 2  bipy, phen, TMphen) adopt a cis -R 2 SnX 4 octahedral structure. A convenient method for the synthesis of a number of novel 1 : 1 diorganotin difluoride complexes using hot acetonitrile is reported and a structure for the unusual adduct, Ph 2 SnF 2 · 0.5 phen, is proposed.

Structural studies in main group chemistry : XXII. Structural and tin-119 mössbauer studies of some five-coordinate triorganotin anions

The structures of two complexes, [Ph3PCH2Ph]+[Bu3SnCl2−]− and [Ph3AsCH2COPh]+[Ph3SnCl2]−, have been determined by X-ray diffraction. Both materials are monoclinic, space group P21/c. Unit cell data for [Ph3PCH2Ph]+−[Bu3SnCl2]− are a 9.8521(6), b 16.9142(4), c 22.3517(7) A, β 91.4235(9)°; and for [Ph3AsCH2COPh]+[Ph3SnCl2]−a 34.9760(3), b 11.1290(5), c 24.2410(2) A, β 108.56(2)°, and both consist of the component ionic species. The organotin anions each have trigonal bipyramidal geometry with equatorial organic groups and axial halogens. In the [Ph3SnCl2]− anion the two SnCl bond distances are the same (2.58(1) and 2.60(1) A), but in [Bu3SnCl2]−, as in [Me3SnCl2]−, they are substantially different (2.573(7) and 2.689(6) A). The SnC bond distances also vary: [Ph3SnCl2]− 2.15(4), 2.16(3) and 2.25(5); [Bu3SnCl2]− 2.21(1), 2.20(2) and 2.29(2) A. Tin-119 Mossbauer data for these and several other similar complexes are also reported.

Synthesis and spectroscopic studies of mono- and di-organotin(IV) derivatives of pyridinecarboxylic acids

Abstract A series of diorganotin bis(pyridinecarboxylates), R2Sn(O.CO.C5H4N-n)2 R = Me, n = 2–4; R = Ph, n = 2 or 3), diorganochlorotin pyridinecarboxylates, R2ClSnO.CO.C5H4N-n (R + Me or Ph, n = 2; R = Me, n = 4) and monoorganodichlorotin pyridinecarboxylates, RCl2Sn(O.CO.C5H4N-2) (R = Bu or Ph), has been synthesised and their structures investigated by 119mSn Mossbauer and infrared spectroscopy. The spectra indicate that, in the solid state, the three dimethyltin bis(pyridinecarboxylates), along with diphenyltin bis(3-pyridinecarboxylate) and dimethylchloro- and diphenylchloro-tin 2-pyridinecarboxylate, adopt a trans-octahedral R2SnX4 geometry. Dimethylchlorotin 4-pyridinecarboxylate, however, possesses a five-coordinate trigonal bipyramidal cis-R2SnX3 stereochemistry, whilst diphenyltin bis(2-pyridinecarboxylate) adopts an octahedral cis-R2SnX4 structure, with two bidentate N-chelating pyridinecarboxylate groups.

The preparation and tin-119m mössbauer spectra of tri-n-butylstannyl esters of heterocyclic and substituted aromatic carboxylic acids

Abstract The 119mSn Mossbauer and infrared data are reported for fifteen tributyltin carboxylates. Although the Mossbauer data at 80 K shows them all to be pentacoordinate polymers, the infrared data indicates that, at room temperature, some of the compounds exist as tetracoordinate monomeric species.

The synthesis and tin-119m Mössbauer spectra of some tetraalkylammonium di- and tri-organohalogenostannate(IV) complexes

Some new organohalogenostannate(IV) complexes of the type M+{R2SnCl2X}− (M = Et4N, Bu4N; R = Me, Bu, Ph; X = Cl, Br, I), M+2{Ph2SnCl2X2}2− (M = Et4N, Bu4N; X = Cl, Br) and M+{R3SnClX}− (M = Et4N, Bu4N; R = Bu, Ph; X = Cl, Br, I) have been isolated and their Mossbauer spectra studied. Definite structural assignments have been made on the basis of the data thus obtained. The attempted synthesis of hexacoordinate triphenyltin complexes, (Bu4N)+2{Ph3SnClX2}2− was not successful, and the reason for this are discussed.

Synthesis of tributylstannyl ethers of carbohydrates

Abstract A series of new tributylstannyl ethers of simple sugars has been prepared by the reaction of bis(tributyltin) oxide with the appropriate mono- or disaccharide; chemical and spectroscopic evidence suggests that the 1-, 4- and 6-hydroxyl groups are the most reactive towards the trialkyltin compound.

Complex formation between organotin chlorides and 2-aminomethyl- and 2-(2′aminoethyl)-pyridine

Abstract The complex formation between organotin chlorides and the potentially bidentate ligands, 2-aminomethylpyridine (AMP) and 2-(2′-aminoethyl)pyridine (AEP), has been investigated. In all cases, adducts with a 1 1 stoichiometry are formed and their solid state configurations have been studied by 119Sn Mossbauer and far infrared spectroscopy. The AMP ligand functions as a bidentate donor towards mono- and di-organotin chlorides to form octahedral complexes, whereas, in the adduct of triphenyltin chloride with AMP, the tin atom is five coordinate and the AMP ligand monodentate. The AEP ligand shows a much reduced tendency to complex the organotin chlorides.