Unprecedented Hexa- and Undecanuclear Frameworks of Two New Tin(IV) Oxo Clusters Resulting from Partial Debenzylation Reactions

Abstract

A new and facile synthetic route to the known neutral cluster ((PhCH 2 ) 2 SnO) 6 [((PhCH 2 ) 2 SnOH) 2 -(CO 3 )] 2 (2) as well as its reactivity toward trifluoromethanesulfonic acid (HO 3 SCF 3 , TfOH) are reported. The solid-state structure of the new solvate 2·6C 7 H 8 has been determined by single-crystal X-ray diffraction. The core of 2 can be described as a pair of coplanar pentanuclear [(PhCH 2 ) 2 SnO] 5 ladders bridged at their ends by two carbonate groups. Successive additions of TfOH to a suspension of 2 in CD 3 CN were monitored by 119 Sn{ 1 H} NMR spectroscopy showing the transformation of the fingerprint of 2 (δ = −244, −246, −306 ppm), via new upfield signals, to a final broad resonance located at δ = −474 ppm. Thereafter, two unprecedented ionic monobenzyltin(IV) oxo clusters, 3 and 4, resulting from a debenzylation reaction and exhibiting unusual hexa-and undecanuclear frameworks, respectively, have been isolated as single crystals. IntroductionOrganotin compounds with Sn-O bonds have a diversity of solid-state structures, from discrete mononuclear compounds to complex clusters and multidimensional networks. Pioneering work in the field of organotin-oxo clusters is attributable to Holmes and Chandrasekhar who in the 1980's discovered several unexpected polynuclear structures and published the first reviews relating to the classification of these compounds [1]. Since then, the inventory of structures has regularly been updated; it reveals a profuse structural diversity [2]. Indeed, on the basis of X-ray crystallographic studies, a great variety of shapes has already been identified for organotin-oxo derivatives which include prismane [3], butterfly [4], ladder [5], O-and Scapped cluster [6], drum [7], cube [8], double cube [9], football cage [10], crown [11], extended cage [12], and coordination polymer types [13]. Moreover, the structural interrelationship between these polynuclear arrangements has been clearly established, highlighting possible mechanisms of interconversion from one form to another [14]. In the past decade, with the growing interest in the assembly of the metal-organic frameworks 0932-0776 / 10 / 1100-1293 $ 06.00 c 2010 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com (MOFs), organotin-oxo moieties have also been used as building blocks for designing supramolecular architectures with remarkably large cavities [15]. From a synthetic point of view, organotin assemblies containing Sn-O bonds are generally obtained from the reaction of organotin precursors (such as organotin oxides and hydroxides) in the presence of phosphonic, phosphinic, carboxylic, and sulfonic acids at room temperature or under reflux conditions. Recently, reactions with arylarsonic acids were also explored [16]. In numerous examples, the cleavage of Sn-C bonds leads to the formation of Sn-O bonds [17].Formerly, investigating the direct synthesis of organic carbonates from carbon dioxide and alcohols promoted by organometallic tin(IV) precursors [18], and during recycling experime...

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

“…The first example, [(R 2 SnO) 3 (R 2 SnOH) 2 (CO 3 )] 2 (15) (R = -CH 2 C 6 H 5 ), was isolated by J.-F. Ma et al, studying the hydrolysis of dibenzyltin dichloride in ethanol in the presence of atmospheric CO 2 [46]. Compound 15 can also be synthesized and characterized as toluene solvate by reacting dibenzyltin oxide with dimethyl carbonate in the presence of toluene and methanol [47]. Meanwhile, for compound 15, the four corners of the inorganic framework are occupied by four bridging hydroxyl groups by changing the reaction conditions (and addition of hypnone).…”