Carlos A. L. Filgueiras

New heptacoordinated tin complexes of 2,6-diacetylpyridine-bis(thiosemicarbazone), H2daptsc, and of 2,6-diacetylpyridine-bis(semicarbazone), H2dapsc. Crystal and molecular structures of [MeSnCl(Hdaptsc)]Cl·MeOH and [MeSnCl(H2dapsc)]Cl2·2H2O

Two new heptacoordinated organotin complexes, [MeSnCl(Hdaptsc)]Cl·MeOH (1) and MeSnCl(H2dapsc)]- Cl2·2H2O (2), have been prepared from MeSnCl3 and H2daptsc and H2dapsc, respectively. Single crystal X-ray diffraction studies showed them to be approximately pentagonal bipyramidal (PBP), with the organic ligands lying in the equatorial plane. H2daptsc and SnCl4 form a complex with the formula [ClSnCl(Hdaptsc)]Cl (3), which is presumed to have an analogous PBP structure. On the other hand, the complex obtained from H2dapsc and Me2SnCl2 is tentatively formulated as [(Me2SnCl2)2(H2dapsc)] (4), and 119Sn Mossbauer spectroscopic evidence suggests an octahedral coordination for the two tin atoms.

The reaction of 2-formylpyridine thiosemicarbazone (HFPT) with tin tetrahalides. Crystal and molecular structure of [SnCl3(FPT)]

Abstract 2-Formylpyridine thiosemicarbazone (HFPT) reacts with the tin tetrahalides (X=Cl, Br, I) with abstraction of HX and the formation of tridentate N,N,S-bonded hexacoordinated species [SnX3(FPT)]. A single crystal X-ray diffraction study of the chloro complex establishes mer-isomerism. Mossbauer data of the products correlate very well with a rehybridization of tin from sp3 to d2sp3 upon complexation.

Tin, palladium and platinum derivatives of 1,1′-bis(diphenylphosphine)ferrocene. Crystal and molecular structures of 1,1′- bis-(diphenylphosphine)ferrocenedichloropalladium(II) and of 1,1′-bis(diphenylphosphine)ferrocenedichloroplatinum(II)

SummaryTen derivatives of 1,1′-bis(diphenylphosphine)ferrocene (BDPF) are described in this paper. The first three, [BDPF·SnCl4] (1), [BDPF·MeSnCl3] (2) and [BDPF·PhSnCl3] (3), present the two phosphorus atoms of the ligand directly bonded to a Sn centre. Two others, [BDPF-PdCl2 (4) and [BDPF·PtCl2] (5), similarly have the ligand BDPF acting as a bidentate species towards a transition metal. The crystal and molecular structures of (4) and (5) are presented here. Two other BDPF complexes were obtained with Pd and Pt, with the transition metals in the zerovalent state, namely [Pd(BDPF)2] (6) and [Pt(BDPF)2] (7). Finally, three trimetallic complexes are also described; [BDPF·Pd(μ-Cl)2SnCl2] (8), [BDPF· Pt(μ-Cl)2SnCl2] (9) and [BDPF·PdClSnCl3] (10).

A Mössbauer investigation of complexes of tin tetrahalides with ambidentate Lewis bases containing nitrogen, sulphur and oxygen

A series of 1 : 1 complexes was prepared with SnX4 (X=Cl, Br, I) and the Lewis bases 2-mercaptobenzothiazole, 2-mercapto-1-methylimidazole, 2-aminothiazole, 2-acetylpyridine, and 2,2′-bis(pyridyl)ketone. The latter two ligands yielded bidentate, N, O-bonded hexacoordinate complexes, whereas the other ligands produced monodentate, N-bonded pentaccoordinate species, as suggested by Mössbauer parameters, which correlate quite well with the IR spectroscopy data.

Complexes with ambidentate ligands derived from pyridine and pyrimidine-Part 2. Platinum(II) complexes

SummarySeven Pt complexes, prepared from thio-, sulphinyl, and carbonyl derivatives of pyridine and pyrimidine, were studied and compared with the analogous nickel complexes. Only when the ligand was an anionic thiolate did Pt form N, S-bonded heterocycles; in all other cases bonding occurred solely through nitrogen, in marked contrast with the Ni systems.

A nova química do estanho

The organometallic chemistry of tin has experienced a phenomenal growth in the last decades. From virtually no important research or applications 50 years ago it has blossomed into a vigorous branch of the chemical sciences. This article aims at reviewing its characteristics and the reasons for this growth, concentrating on the current trends and the latest research in the area.

Mössbauer studies of heterobimetallic and heterotrimetallic compounds containing iron and tin

A series of ferrocene derivatives was prepared and studied by57Fe and119Sn Mössbauer spectroscopy, as well as by other techniques such as NMR and IR spectroscopies. These complexes can be divided into three types: mercurated, organotin derivatives of ferrocene, and bi- and trimetallic derivatives of 1,1′-bis(diphenylphosphino)ferrocene. Iron did not show great variation in its Mössbauer parameters in the compounds, in spite of their diversity; tin, however, gave important Mössbauer data for the elucidation of bonding and structural features of the complexes.

Complexes of disulphoxides with triphenyltin chloride

Six new complexes have been prepared with Ph3SnCl and the disulphoxides rac-(PrSOCH2)2, rac-cis-PhSOCH*CHSOPh, meso-(PhSO)2CH2, rac-(PhSO)2CH2, meso-(PhSOCH2)2, and rac-(PhSCOCH2)2. The first of these complexes is a bridged 2:1 acid: base adduct, whereas the others seem to be 1:1 chelated compounds. Several features of the complexes were studied by IR spectroscopy, X-Ray crystallography and NMR spectroscopy.

Cyclization of N-alkyldithiocarbamates in alkaline media, a counter example of well-known chemistry – an experimental and theoretical study

In strong alkaline media, the reaction of 2-(tert-butylamino)ethanol (3: R = But) with CS2 at 0°C produced a cyclic dithiocarbamate, 3-tert-butylthiazolidine-2-thione (1: R = But), rather than alkaline metal or ammonium salts of [S2CN(But)CH2CH2OH]−. This is in contrast to isolation of stable alkaline metal or ammonium salts of [S2CN(R)CH2CH2OH]− (R = Me, Et, Pr, or CH2CH2OH) obtained in analogous reactions. The use of Ni(OAc)2, both as a source of Ni(II) and a weaker base, in a one-pot reaction with (3: R = But) and CS2, successfully gave the first reported metal complex of [S2CN(But)CH2CH2OH]−, namely [Ni{S2CN(But)CH2CH2OH}2] (2: R = But). Compounds 1 and 2 have been fully characterized by infrared and NMR spectroscopies, and by X-ray crystallography. DFT calculations on the cyclization and stabilities of [S2CN(R)CH2CH2OH]− (R = Pr and But) have been carried out.

1,1,1-Tris(diphenylphosphinemethyl)ethane complexes of nickel and platinum with tin

SummaryThis paper describes a series of bimetallic compounds derived from the starting complexes [Ni(tdpme)Cl2] and [Pt(tdpme)Cl2] [where tdpme = 1,1,1-tris(diphenylphosphinemethyl) ethane, MeC(CH2PPh2)3] upon reaction with Ph3SnCl and NaBH4, as well as with SnCl2. In the first case, a direct bond between tin and the transition metal is formed (with concomitant reduction to the 1 + oxidation state for the nickel species), whereas SnCl2 forms chlorine bridges with the transition metals.