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.

A new recipe for the synthesis of diorganotin bis(O-alkylorganophosphonate)s, R12Sn{O(P)(O)(OR1)R}2 [R = R1 = methyl (1); R1 = 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)(OR1)2, 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 R1SnI or R12SnI2 intermediate via the oxidative addition of alkyl iodide on tin. Evidence in support of the formation of organotin species comes from the isolation of Me2Sn{O(P)(O)(OiPr)Me}2 (6) from the direct reaction of tin metal with MeP(O)(OiPr)2 in the presence of methyl iodide. The method has also been extended to isolate Zn{OP(O)(OMe)Me}2 (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.

Synthesis and structural studies of diorganotin(IV)-based coordination polymers bearing silaalkylphosphonate ligands and their transformation into colloidal domains.

The contribution of silaalkylphosphonic acids Me3SiCH2P(O)(OH)2 (1) and Me3SiC(CH3)2P(O)(OH)2 (2) as ligands was demonstrated for the first time by the isolation of new diorganotin(IV) phosphonates Et2Sn{OP(O)(OH)CH2SiMe3}(OSO2Me) (3), (Et2Sn)6{O3PC(CH3)2SiMe3}4(OSO2Me)4 (4), and Et2Sn(O3PCH2SiMe3) (5). X-ray crystallographic studies of 1-4 are presented. The structures of 1 and 2 adopt extended motifs by virtue of P-OH···O═P-type hydrogen bonding interactions. The molecular structure of 3 is composed of a dimer formed by bridging hydrogen phosphonate groups, while the sulfonate group appended on each tin atom acts in a µ2-bridging mode to afford the formation of one-dimensional coordination polymer featuring alternate eight-membered [-Sn-O-P-O-]2 and [-Sn-O-S-O-]2 rings. The asymmetric unit of 4 is composed of two crystallographically unique trinuclear tin phosphonate clusters with a Sn3(µ3-PO3)2 core linked together by coordinative association of a µ2-sulfonate group, while the remaining sulfonates are involved in the construction of a two-dimensional self-assembly. The identity of 1-5 in solution was established by IR and multinuclear ((1)H, (13)C, (31)P, (119)Sn) NMR spectroscopy. The presence of silaalkyl group in 5 imparts unusual solubility in hydrocarbon, aromatic, and ether solvents. As a consequence, the formation of colloidal particles of 5 featuring rodlike morphology was achieved by ultrasonication of a solution in ethanol-chloroform mixture.

The synergy between electrochemical substrate oxidation and the oxygen reduction reaction to enable aerobic oxidation.

Aerobic substrate oxidation reactions catalyzed by a heterogeneous catalyst can be looked upon as two independent half-cell reactions, viz. anodic substrate oxidation and the cathodic oxygen reduction reaction (ORR). In this context, Fe PANI/C, a well-known catalyst for the ORR, is chosen to validate this hypothesis, wherein the anodic reaction is hydrazine oxidation. Fe PANI/C shows excellent activity in terms of the electrochemical ORR and hydrazine oxidation in both alkaline aqueous and non-aqueous media and taken together the aerobic oxidation efficacy of hydrazine-like small organic molecules is correlated with the electrochemical outcomes.

Rare Breast Malignancy Subtypes: A Cytological, Histological, and Immunohistochemical Correlation.

BACKGROUND: Breast malignancies encompass various subtypes which differ in their clinical presentations, outcomes, and response to the treatment regimens. Thus, a proper histological diagnosis and a special mention of the rare histologic subtypes are required to formulate clear recommendations of their treatment protocols. MATERIALS AND METHODS: This is a 1-year retrospective study highlighting the rarely encountered subtypes on the mastectomy specimens received. RESULTS: We encountered only 11 rare cases out of the total 153 mastectomy specimens received. The rare subtypes were as follows mucinous cystadenocarcinoma (0.6%), mucinous carcinoma (0.6%), dermatofibrosarcoma protuberans (0.6%), Squamous cell carcinoma (0.6%), papillary carcinoma (2.6%), medullary carcinoma (0.6%), and malignant mesenchymal tumor (1.3%). CONCLUSION: Our data suggest that these variants are distinct clinicopathological entities with a unique hormonal receptor status. Scant information is available on the rare breast tumor subtypes.

Synthesis, characterization and selective de-esterification of diorganotinbis(O-methylphosphite)s.

A one-pot reaction between di-n-butyl/diethyl/dimethyltin dichloride and dimethylphosphite (MeO)2P(O)H in a solvent free medium (120 °C, 18 h) proceeds smoothly to yield the corresponding diorganotinbis(O-methylphosphite)s, [R2Sn(OP(O)(OMe)H)2]n [R = n-Bu (1), Et (2), Me (3)]. The identity of 1-3 has been established by IR, multinuclear ((1)H, (13)C, (31)P, (119)Sn) NMR, powder X-ray diffraction (PXRD) and X-ray crystallography. The coordination framework in each case adopts a one-dimensional structural motif comprising an infinite array of eight-membered [Sn-O-P-O]2 cyclic rings, with the phosphite ligands acting in a bridging bidentate mode. The structures are extended to two- (for 1) and three-dimensional (for 2, 3) assemblies by virtue of C-H···O hydrogen bonding interactions. The stability and bulk properties of 1-3 have been investigated upon exposure to humid laboratory conditions using (1)H NMR, PXRD and SEM studies. The results conform to a unique chemical modification of 1-3 involving selective de-esterification of P-OMe bonds and the formation of corresponding diorganotinbis(phosphite)s, [R2Sn(OP(O)(OH)H)2]n (1a-3a), as insoluble solids. The results obtained from impedance studies (σ = 10(-4)-10(-6) S cm(-1); E(a) = 0.33-0.42 eV) reveal potential application of 1a-3a as proton conducting materials.