C,N-chelated organotin(IV) trifluoromethanesulfonates: Synthesis, characterization and preliminary studies of its catalytic activity in the direct synthesis of dimethyl carbonate from methanol and CO2

(N),C,N-Coordinated Heavier Group 13-15 Compounds: Synthesis, Structure and Applications

The aim of this review is to summarize recent achievements in the field of (N),C,N-coordinated group 13-15 compounds not only regarding their synthesis and structure, but mainly focusing on their potential applications. Relevant compounds contain various types of N-coordinating ligands built up on an ortho-(di)substituted phenyl platform. Thus, group 13 and 14 derivatives were used as single-source precursors for the deposition of semiconducting thin films, as building blocks for the preparation of high-molecular polymers with remarkable optical and chemical properties or as compounds with interesting reactivity in hydrometallation processes. Group 15 derivatives function as catalysts in the Mannich reaction, in the allylation of aldehydes or activation of CO₂ . They were used as transmetallation reagents in transition metal catalysed coupling reactions. The univalent species serve as ligands for transition metals, activate alkynes or alkenes and are utilized as catalysts in the transfer hydrogenation of azo-compounds.

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

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.

Neutral and cationic phosphine and arsine complexes of tin(iv) halides: synthesis, properties, structures and anion influence

The reaction of trans-[SnCl₄(PR₃)₂] (R = Me or Et) with trimethylsilyltriflate (TMSOTf) in CH₂Cl₂ solution substitutes one chloride to form [SnCl₃(PR₃)₂(OTf)]; addition of excess TMSOTf does not substitute further chlorides. The complexes have been fully characterised by microanalysis, IR and multinuclear NMR (¹H, ¹³C{¹H}, ¹⁹F{¹H}, ³¹P{¹H}, ¹¹⁹Sn) spectroscopy. The crystal structure of [SnCl₃(PMe₃)₂(OTf)] revealed mer-chlorines and trans-phosphines. In contrast, trans-[SnBr₄(PR₃)₂], [SnCl₄{Et₂P(CH₂)₂PEt₂}], [SnCl₄{o-C₆H₄(PMe₂)₂}] and [SnCl₄{o-C₆H₄(AsMe₂)₂}] did not react with TMSOTf in CH₂Cl₂ solution even after 3 days. The arsine complexes, [SnX₄(AsEt₃)₂] (X = Cl, Br), were confirmed as trans-isomers by similar spectroscopic and structural studies, while attempts to isolate [SnI₄(AsEt₃)₂] were unsuccessful and reaction of SnX₄ with SbR₃ (R = Et, ⁱPr) resulted in reduction to SnX₂ and formation of R₃SbX₂. trans-[SnCl₄(AsEt₃)₂] is converted by TMSOTf into [SnCl₃(AsEt₃)₂(OTf)], whose X-ray structure reveals the same geometry found in the phosphine analogues, with the triflate coordinated. The salts, [SnCl₃(PEt₃)₂][AlCl₄] and [SnCl₂(PEt₃)₂][AlCl₄]₂ were made by treatment of [SnCl₄(PEt₃)₂] with one and two mol. equivalents, respectively, of AlCl₃ in anhydrous CH₂Cl₂, whereas reaction of [SnCl₄(AsEt₃)₂] with AlCl₃ produced a mixture including Et₃AsCl₂ and [Et₃AsCl][Sn(AsEt₃)Cl₅] (the latter identified crystallographically). In contrast, using Na[BAr^F] (BAr^F = [B{3,5-(CF₃)₂C₆H₃}₄]^-) produced [SnCl₃(PEt₃)₂][BAr^F] and also allowed clean isolation of the arsine analogue, [SnCl₃(AsEt₃)₂][BAr^F]. [SnCl₄{o-C₆H₄(PMe₂)₂}] also reacts with AlCl₃ in CH₂Cl₂ to form [SnCl₃{o-C₆H₄(PMe₂)₂}][AlCl₄] and [SnCl₂{o-C₆H₄(PMe₂)₂}][AlCl₄]₂. Multinuclear NMR spectroscopy on the [AlCl₄]^- salts show that δ³¹P and δ¹¹⁹Sn move progressively to high frequency on conversion from the neutral complex to the mono- and the di-cations, whilst ¹J(¹¹⁹Sn-³¹P) follow the trend: [SnCl₃{o-C₆H₄(PMe₂)₂}]⁺ > [SnCl₄{o-C₆H₄(PMe₂)₂}] > [SnCl₂{o-C₆H₄(PMe₂)₂}]²⁺. DFT studies on selected complexes show only small changes in ligand geometries and bond lengths between the halide and triflate complexes, consistent with the X-ray crystallographic data reported and the HOMO and LUMO energies are relatively unperturbed upon the introduction of (coordinated) triflate, whereas the energies of both are ca. 4 eV lower in the cationic species and reveal significant hybridisation across the pnictine ligands.

Triorganotin(iv) cation-promoted dimethyl carbonate synthesis from CO2and methanol: solution and solid-state characterization of an unexpected diorganotin(iv)-oxo cluster

NovelC,N-chelated organotin(iv) complexes bearing weakly coordinating carborane moieties were prepared and used as a catalyst precursor for the direct synthesis of dimethyl carbonate (DMC) from CO₂and methanol.

Dimethyl carbonate synthesis from carbon dioxide using ceria–zirconia catalysts prepared using a templating method: characterization, parametric optimization and chemical equilibrium modeling

In this paper, a series of Ce_xZr_1−xO₂ solid solution spheres were synthesized by exo- and endo-templating methods and tested for dimethyl carbonate (DMC) synthesis using direct conversion of CO₂.

C,N-Chelated organotin(iv) azides: synthesis, structure and use within click chemistry

Novel organotin(iv) azides were employed as building blocks to prepare various organotin(iv) tetrazolides or triazolides.

Recent advances in dialkyl carbonates synthesis and applications

Dialkyl carbonates are important organic compounds and chemical intermediates with the label of "green chemicals" due to their moderate toxicity, biodegradability for human health and environment. Indeed, owing to their unique physicochemical properties and versatility as reagents, a variety of phosgene-free processes derived from CO or CO2 have been explored for the synthesis of dialkyl carbonates. In this critical review, we highlight the recent achievements (since 1997) in the synthesis of dialkyl carbonates based on CO and CO2 utilization, particularly focusing on the catalyst design and fabrication, structure-function relationship, catalytic mechanisms and process intensification. We also provide an overview regarding the applications of dialkyl carbonates as fuel additives, solvents and reaction intermediates (i.e. alkylating and carbonylating agents). Additionally, this review puts forward the substantial challenges and opportunities for future research associated with dialkyl carbonates.

Comparison of reactivity of C,N-chelated and Lappert’s stannylenes with trimethylsilylazide

Two mixed amido-azido tin(IV) species bearing either C,N-chelating or bulky amido ligands were prepared by the reaction of the corresponding stannylene (e.g., Sn[N(SiMe3)2]2 (1) or (LCN)2Sn (2, LCN = 2-(N,N-dimethylaminomethyl)phenyl)) with Me3SiN3. Both products of the oxidative addition, Sn[N(SiMe3)2]3N3 (3) and (LCN)2Sn[N(SiMe3)2]N3 (5), respectively, were fully characterized by both multinuclear NMR spectroscopy and XRD analysis. Heating of a mixture of 2 and Me3SiN3 up to 100 °C lead to the formation of a novel dimeric species (LCN)2Sn(μ-NSiMe3)2Sn(LCN)2 (4), where the two tin atoms are bridged by two NSiMe3 ligands, thus forming a four-membered diazadistannacycle. DFT calculations were also carried out to support the proposed reaction mechanisms.