CO2 Derivatives of Molecular Tin Compounds. Part 1: Hemicarbonato and Carbonato Complexes

Abstract

This review focuses on organotin compounds bearing hemicarbonate and carbonate ligands, and whose molecular structures have been previously resolved by single-crystal X-ray diffraction analysis. Most of them were isolated within the framework of studies devoted to the reactivity of tin precursors with carbon dioxide at atmospheric or elevated pressure. Alternatively, and essentially for the preparation of some carbonato derivatives, inorganic carbonate salts such as K2CO3, Cs2CO3, Na2CO3 and NaHCO3 were also used as coreagents. In terms of the number of X-ray structures, carbonate compounds are the most widely represented (to date, there are 23 depositions in the Cambridge Structural Database), while hemicarbonate derivatives are rarer; only three have so far been characterized in the solid-state, and exclusively for diorganotin complexes. For each compound, the synthesis conditions are first specified. Structural aspects involving, in particular, the modes of coordination of the hemicarbonato and carbonato moieties and the coordination geometry around tin are then described and illustrated (for most cases) by showing molecular representations. Moreover, when they were available in the original reports, some characteristic spectroscopic data are also given for comparison (in table form). Carbonato complexes are arbitrarily listed according to their decreasing number of hydrocarbon substituents linked to tin atoms, namely tri-, di-, and mono-organotins. Four additional examples, involving three CO2 derivatives of C,N-chelated stannoxanes and one of a trinuclear nickel cluster Sn-capped, are also included in the last part of the chapter.

CO2 Derivatives of Molecular Tin Compounds. Part 2: Carbamato, Formato, Phosphinoformato and Metallocarboxylato Complexes

“…The carbamate moiety is terminally O-bonded to Sn [Sn−O = 2.1346(16) Å] and its orientation can be viewed almost perpendicular to the NCCCN plane of the β-diketiminate ligand ( Figure 5). This mode of coordination is unusual for carbamates and is similar to that observed in the case of hemicarbonato derivatives [1]. The X-ray structure of complex 7 has not been reported but the spectroscopic data are very similar to 6 ( Table 2) and the authors mention that for both compounds, the insertion reaction is irreversible, even under reduced pressure.…”

“…N,N -diphenylurea is formed as byproduct (4%). From a mechanistic point of view, the hemicarbonato tin complex, n-Bu 2 Sn(OMe)(OCO 2 Me), resulting from the reactivity of CO 2 with n-Bu 2 Sn(OMe) 2 [1,31], is claimed as the key intermediate of the reaction. In the case of reactions involving n-Bu 2 Sn(OBu-n) 2 , the authors also showed that the starting tin complex could be regenerated after the first catalytic run (by reacting with n-BuOH) and could thus be recycled without loss of activity.…”

“…The first X-ray crystallographic investigation on a tin complex bearing a carbamato ligand was reported by Zakharov et al in 1980, as part of studies on organotin isocyanate derivatives [42]. Thus, the Russian group characterized at the solid-state the structure of the trimethyltin(IV) ester of N-trimethylstannylcarbamic acids, Me 3 SnNHC(=O)-OSnMe 3 (1), which describes a polymeric arrangement displaying a zigzag one-dimensional infinite chain along the c-axis (Figure 1). The organization of 1 consists of SnMe 3 moieties bridged by carbamate dianions.…”

“…Long considered simply as abundant and chemically inert waste, but with devastating effects, carbon dioxide is now differently viewed by chemists, considered and accepted as a promising C1 building block, useful for a wide range of reactions and leading to a wide diversity of organic compounds. In this quest to transform CO 2 into chemicals with higher added value, coordination and organometallic chemistry played-and continue to play-an important and determining role in facilitating its activation [1]. Since the first resolution of an X-ray crystal structure highlighted the metal coordination of a CO 2 molecule-it was in 1975 that M. Aresta's group published the characterization of a (carbon dioxide)bis(tricyclohexylphosphine) nickel complex [2]-advances and knowledges relative to carbon dioxide binding modes have continued to progress, and have proved particularly beneficial in catalysis and organic synthesis.…”

“…During the last decade, the reactivity of main group elements, and in particular metals and metalloids from group 14 (Si, Ge, Sn, Pb), toward small molecules also aroused a growing interest [15,16]. In this context and based on our previous work in this field, we have recently reviewed molecular organotin compounds bearing hemi-carbonate and carbonate ligands and which result from the reactivity of tin precursors towards carbon dioxide [1]. In this second part, we continue to explore from a structural point of view the molecular derivatives of tin which result from the insertion of carbon dioxide into the Sn-X bonds (X = N, H, P).…”