Fine-Tuned Characterization at the Solid/Solution Interface of Organotin Compounds Grafted onto Cross-Linked Polystyrene by Using High-Resolution MAS NMR Spectroscopy

Abstract

The structural characterization of organotin compounds that are grafted onto insoluble cross‐linked polymers has necessarily been limited to elemental analysis, infrared spectroscopy, and in a few instances, solid‐state NMR spectroscopy. This important bottleneck in the development of such grafted systems has been addressed by using high‐resolution magic angle spinning (hr‐MAS) NMR spectroscopy. The great potential of this technique is demonstrated through the structural characterization of diphenylbutyl‐(3,4) and dichlorobutylstannanes (5,6), grafted onto divinylbenzene cross‐linked polystyrene by means of a suitable linker (1, 2). First, conditions suitable for the application of hr‐MAS NMR spectroscopy were identified by characterizing the 1H resonance line widths of the grafted organotin moiety following swelling of the functionalized beads in eight representative solvents. The presence of clearly identifiable tin coupling patterns in both the 1D 13C and 2D 1H‐13C HSQC spectra, and the incorporation of 119Sn chemical shift and connectivity information from hr‐MAS 1D 119Sn and 2D 1H‐119Sn HMQC spectra, provide an unprecedented level of characterization of grafted organotins directly at the solid/liquid interface. In addition, the use of hr‐MAS 119Sn NMR for reaction monitoring, impurity detection, and quantification and assessment of the extent of coordination reveals its promise as a novel tool for the investigation of polymer‐grafted organotin compounds. The approach described here should be sufficiently general for extension to a variety of other nuclei of interest in polymer‐supported organometallic chemistry.

Triorganotin 4-isopropylbenzoates as model transesterification catalysts for triorganotin carboxylates grafted to cross-linked polystyrene

“…The pollution problems raising from the use of organotins can be conveniently addressed by covalently grafting the organometallic moiety to a macromolecular support [12], thus lowering or even preventing tin release into the environment [13], leading to the so-called ''clean organotin derivatives'' [14][15][16][17][18][19]. Tin compounds grafted to polymeric carbon chains experience growing interest since alkyltin moieties in polymers or copolymers mimic well the properties of their non-polymeric organotin analogues.…”

Application of computational modeling to analyze reactive organotin(IV) species

“…Gaussian is premier computational modeling software for applying COTs to generate COMs (greater details in the following section) with extremely detailed analyses per molecule or molecular system. The accuracy, or reliability, of the COMs for the molecules studied in this research was examined in relation to X-ray crystallography (XRC) (Bruker Apex Small Molecule X-ray Crystallographer) and solid-state 119 Sn NMR (Avance 250 Digital MAS NMR to an SGI 02 Silicon Graphics Computer using xwinnmr version 2.1) [12,[14][15][16][17].…”

“…The number of properties determined experimentally is expanded by applying a reliable COT to generate a COM of the molecule by Gaussian. Thus, Gaussian computes an expanded range of data about the molecular properties by starting with the structural determinations of the experimental methods [10,14,15,18].…”

Cross-linked polystyrene resins containing triorganotin-4-vinylbenzoates: Assessment of their catalytic activity in transesterification reactions

“…Several insoluble tri-and dialkyltin grafted polymers have already been synthesized, starting from commercial polystyrene resins cross-linked with 1,4-divinylbenzene [13][14][15][16][17][18]. All the synthetic procedures used in previous reports [18] have the common disadvantage to start from an insoluble reactant, which makes the reaction sluggish and difficult to control.…”

“…Co-polymerization to cross-linked resins involving triorganotin carboxylate monomers is believed to address this issue and is presented in the present paper as an alternative strategy. More particularly, we have addressed the synthesis of cross-linked resins, having a structure closely related to that of Amberlite IRC-86 [19], starting, however, from triorganotin p-vinylbenzoates rather than acrylates as suitable monomers, since cross-linked polystyrenes proved previously to be convenient insoluble supports giving rise to satisfactory catalytic activities in other organotin systems [13][14][15][16][17][18], unlike Amberlite IRC-86, scoring less satisfactorily. In fact, although it is known [20] that organometallic monomers can inhibit the polymerization process, this synthetic route is nevertheless explored since it enables one to skip further functionalization steps, potentially limited by unfavourable diffusion due to the cross-linking, as observed with Amberlite IRC-86 derivatives [19].…”