(Organo)thallium (I) and (II) chemistry: Syntheses, structures, properties and applications of subvalent thallium complexes with alkyl, cyclopentadienyl, arene or hydrotris(pyrazolyl)borate ligands

Heteronuclear Heavy Alkenes E=E' (E, E' = Group 14 Elements): Germasilenes, Silastannenes, Germastannenes...Next Stop?

Publisher Summary The literature on organotin chemistry up to 1970 is summarized in the excellent monographs by Neumann and Poller and in the volumes edited by Sawyer. Since that date, periodic reviews of advances in the field, and accounts of some selected aspects have been published, but there has been no attempt to bring the general survey up to date. In this article, one has attempted to review the progress that has been made since 1970, and to give an account of the present status of the field, briefly sketching in the earlier background. About 1000 papers are published annually on organotin chemistry, and only 5% of these have been able to be included. One has deliberately avoided treating in depth those aspects of the subject that have been thoroughly reviewed recently, and in particular, one has avoided duplicating the excellent surveys of the use of organotin compounds in organic synthesis.

Recent Advances in Organotin Chemistry

A perfect tin! Two 15-nuclear tin metalloid clusters [Sn15Z6] (Z=N(2,6-iPr2C6H3)(SiMe2X); X=Me, Ph), having an unprecedented body-centered metal core (see picture; only N atoms of the amide ligands shown), were prepared by reduction of the appropriate amidotin(II) chloride with KC8 or Li[BHsBu3]. Mossbauer spectra showed two distinct quadrupole-splitting sites in the ratio of 1.5:1 for the Sn9 atoms and the six amido-bound tin atoms.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200600292

Higher‐Nuclearity Group 14 Metalloid Clusters: [Sn9{Sn(NRR′)}6]

Mossbauer spectroscopy is now routinely used in the characterization of tin compounds. Information is readily obtained about the oxidation state of the metal, and the number, type, and arrangement of the ligands. The basic principles of interpretation have been established for some time, and major reviews appeared about ten years ago.1,2 Since then, further advances have been made in the application of the point-charge model for quadrupole splitting, and in the interpretation of data for transition-metal complexes involving Sn-donor ligands. There have also been developments in studies of the recoil-free fraction, and in the calibration of isomer-shift and quadrupole-splitting scales in terms of electron populations. These topics are reviewed in this chapter, together with matrix-isolation studies and some recent work on tin(II) systems.

Structure and Bonding in Tin Compounds

Mossbauer spectra of SnR2[R = CH(SiMe3)2] and of 16 of its derivatives have been recorded. The latter fall into two classes: (i) the dialkylstannylene complexes such as [Cr(CO)5(SnR2)] in which bivalent Sn is three-co-ordinate: and (ii) dialkylstannylene insertion products into C–X, M–H, M–Cl, M–Me, or M–M bonds (M = a transition metal, X = halogen) such as [Fe(η-C5H5)(CO)2(SnR2Cl)], in which quadrivalent tin is four-co-ordinate. The compound SnR2 and class (i) complexes are characterised by isomer shifts of 2.15 ± 0.1 mm s–1 relative to BaSnO3 and large quadrupole splittings [2.31 (for SnR2) or 4.25 ± 0.2 mm s–1 for class (i)]. Class (ii) complexes show lower isomer shifts (1.49 ± 0.25 mm s–1) and quadrupole splittings (<2.37 mm s–1). Magnetic Mossbauer measurements on SnR2 and [Cr(CO)5(SnR2)] show that for both complexes the sign of the quadrupole coupling constant eQVzz, is negative and hence Vzz the principal component of the field gradient tensor, is positive.

Jack Silvet

Papers

Subvalent Group 4B metal alkyls and amides. Part III Mössbauer spectroscopy studies of bis[bis(trimethylsilyl)methyl]tin(II) and its derivatives