Reactivity of Elemental Tin and Zinc toward Organophosphonic Acid Dialkyl Esters: A New One-Pot Recipe for the Synthesis of Coordination Assemblies Derived from O-Alkylorganophosphonate Ligands

Abstract

A new recipe for the synthesis of diorganotin bis(O-alkylorganophosphonate)s, RSn{O(P)(O)(OR)R} [R = R = methyl (1); R = ethyl and R = methyl (2), allyl (3), 2-thienyl (4), benzyl (5)], has been developed from the direct reaction of elemental tin (powder) with organophosphonic acid dialkyl esters, RP(O)(OR), in the presence of a catalytic amount of potassium iodide under ambient conditions (130 °C, 18-20 h). The key steps in the proposed catalytic cycle involve the monodealkylation of phosphonate diester and in situ generation of a RSnI or RSnI intermediate via the oxidative addition of alkyl iodide on tin. Evidence in support of the formation of organotin species comes from the isolation of MeSn{O(P)(O)(OPr)Me} (6) from the direct reaction of tin metal with MeP(O)(OPr) in the presence of methyl iodide. The method has also been extended to isolate Zn{OP(O)(OMe)Me} (7) using metallic zinc as the precursor. All of the compounds have been characterized by IR and NMR studies as well as X-ray crystallography for 2, 4, 6, and 7.

Formation of Metal-Based 21- and 22-Membered Macrocycles from Dinuclear Organotin Tectons and Ditopic Organic Ligands Carrying Carboxylate or Dithiocarbamate Groups

“…The opportunities related to assemblies based on the combination of metal ions and organic ligands are exponentially increasing as seen from the number of publications in this field. − This can be attributed to the large number of metals in the periodic table of the elements with varying properties such as coordination number and geometry, oxidation state, color, magnetic moments, etc., which, in combination with organic ligands, give an almost infinite number of zero-, one-, two-, and three-dimensional (0D, 1D, 2D, and 3D) aggregates. − …”

“…At the beginning of the 21st century, organotin compounds started to receive attention in the field of metal-coordination driven self-assembly, and since then, the number of reports on macrocyclic, cage-type, and infinite 1D, 2D, and 3D coordination polymers is increasing. When compared to constructs derived from non-organometallic metal complexes, assemblies carrying organic groups attached by covalent binding to the metal atom are appealing due to the opportunity of structural and functional modification.…”

“…The possibility of modifying the chemical composition of the substituents attached to the metal enables one to vary the electronic and steric properties around the metal atom and to functionalize the interior and periphery of the resulting molecules, which is important for potential applications such as adsorption, molecular recognition, supramolecular catalysis, etc . Organotin compounds exhibit relatively inert metal–carbon bonds with aliphatic and aromatic substituents and can be frequently manipulated under non-inert conditions. − Moreover, the coordination chemistry of organotin compounds is quite predictable, in particular when bidentate ligands such as carboxylates or dithiocarbamates are used. Diorganotin dicarboxylates and bis-dithiocarbamates, i.e., R 2 Sn­(OOCR) 2 and R 2 Sn­(dtc) 2 , are generally six-coordinate complexes with skewed-trapezoidal bipyramidal coordination environments, while the triorganotin analogues are essentially four-coordinate with distorted tetrahedral geometry, i.e., R 3 Sn­(OOCR) and R 3 Sn­(dtc). , …”

Organotin Phosphates Assembled from a Sterically Hindered Organophosphate, ArOP(O)(OH)2, (Ar = 2,6-(CHPh2)2-4-i-Pr-C6H2): Syntheses and Structures

“…The structural diversity of organooxotin compounds is extremely impressive and is achieved by surprisingly simple reactions involving an organotin precursor (organotin chlorides, -oxides, -hydroxides, and -oxide-hydroxides) and an appropriate protic acid (carboxylic acids, phosphinic acids, sulfonic acids, phosphonic acids, and phosphoric acid monoester). − Among the phosphorus-based acids, interestingly, phosphinic [R 2 P­(O)­(OH)] and phosphonic acids [RP­(O)­(OH) 2 ] have received much greater attention than phosphates [ROP­(O)­(OH) 2 ]. − On the other hand, it is well-known that the P–O linkage in phosphates makes these ligands more flexible because of the hinge oxygen atom compared to many phosphonic acids where the phosphorus atom is directly linked to the organic unit . Indeed, previous studies on the reactions of phosphates with organotin substrates, though sparse, have already revealed significant structural variation .…”

Tailoring Structural Diversity in Dimethyltin Carboxylates by the pH-Controlled Hydrothermal Approach

“…Our previous studies have been devoted to develop new methods for the synthesis of higher-dimensional diorganotin­(IV) coordination assemblies derived from mixed-ligand phosphonate and sulfonate ligands . The method relies upon a two-step approach involving the synthesis of diorganotin­(alkoxy)­alkanesulfonates, [R 2 Sn­(OR)­OSO 2 R] n (R = alkyl), and subsequent reaction of these reactive precursors with phosphonic acid under mild conditions.…”