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A number of dialkyltin(1V) salts of phosphorus oxy-acids R2Sn(P02H2)2 (R = CH,, C2H5, 11-CqHg), R2SnP03X (R = CH,, CzH5, 11-C4Hg, X = H ; R = CH,, X = F, OH), and [(CH3)2Sn]3(P04)2 have been prepared in aqueous solution from the appropriate dialkyltin(1V) dichloride and the sodium salts of phosphorus oxy-acids.Infrared and L19Sn Mossbauer spectra of the dialkyltin dihypophosphites, R2Sn(P02H2)2, are consistent with hexacoordination for tin with the alkyl groups in trata-octahedral positions and bidentate bridging hypophosphite groups coordinated through oxygens. For the dialkyltin phosphites, R2SnP03X, polymeric structures with a non-linear R2Sn arrangement are involved, and the magnetic hyperfine Mossbauer spectrum (X = F) is consistent with either distorted tratls-octahedral or distorted trigonal bipyramidal structures (with both apical or both equatorial methyl groups). In [(CH3)2Sn]3(P0,)2 the three tin environments are indistinguishable by Mossbauer spectroscopy, but the high value of the asymmetry parameter q 2. 0.8 suggests penta-rather than hexacoordination about tin, for which a t least one three-coordinate oxygen per formula unit must be invoked.Un nombre de sels de dialkylstannates d'oxy-acides de phosphore R2Sn(P02H2)2 (R = CH3, CZHS, rr-C4Hg), R2SnP03X (R = CH3, C2HS, n-C4H9, X = H; R = CH3, X = F, OH) et [(CH3)2Sn13(P04)2 ont ete prepare en solution aqueuse a partir ~L I dichlorure de dialkylstannate adCquat et des sels de sodium des oxy-acides de phosphore. L'infrarouge et le spectre de Mossbauer de "'Sn des dihypophosphites de dialkylstannate, R2Sn(P02H2)2, sont consistants avec I'hexacoordination de I'Ctain avec les groupes alkyles dans des positions octahkdrique-rrans avec les groupes hypophosphites bidentates formant des ponts par coordination avec les oxygenes. En ce qui concerne les phosphites de dialkylstannate, R2SnP03X, des structures polymCriques avec une non-linearit6 pour les arrangements du RzSn sont impliqukes, et le spectre magnetique hyperfin de Mossbauer (X = F), est consistant soit avec une forme octahedrique-tratrs distordue, ou une forme bipyramidale trigonale distordue (avec les deux groupes methyles apicaux, ou Cquatoriaux). Dans [(CH3)2Sn]3(P04)2, les trois Ctains environnants sont indistinguables par la spectroscopie de Mossbauer, mais la grande v a l e~~r du parametre assymktrique 11 E 0.8 suggere une pentacoordination plutdt qu'une hexacoordination par rapport a I'Ctain, pour conclure enfin que I'un des trois oxygenes coordinants par unite de formule doit &tre invoquk.[Traduit par le journal]Can.

Trimethyltin hypophosphite, Me3SnPO2H2, bis(trimethyltin) phosphite dihydrate, (Me3Sn)2PO3H.2H2O, and bis(triphenyltin) phosphite, (Ph3Sn)2PO3H, have been obtained from the organotin chloride and aqueous solutions of the sodium salt of the corresponding phosphorus oxy-acid. (Me3Sn)2PO3H.2H2O can be dehydrated under vacuum at 25 °C, but disproportionation occurs on heating. Tris(trimethyltin) orthophosphate, (Me3Sn)3PO4, was prepared from trimethyltin chloride and silver phosphate in methanol and gave an adduct formulated as [Formula: see text] after recrystallization from 1,4-dioxane. Vibrational spectra and Mössbauer data for Me3SnPO2H2 are consistent with a trigonal bipyramidal structure in which planar Me3Sn groups are bridged symmetrically by PO2H2 groups. The Mössbauer spectra of (Me3Sn)2PO3H, (Ph3Sn)2PO3H, and (Me3Sn)2PO3H.2H2O suggest that the two tin atoms are in similar (probably pentacoordinate) environments, implying at least one three coordinate oxygen per formula unit. For (Me3Sn)3PO4, the vibrational spectra, Mössbauer data, and physical properties are consistent with a weakly associated structure in which all three tin atoms are in similar environments. It is suggested that association is achieved via the phosphoryl (P=O) oxygen atom, which is weakly coordinated to three tin atoms leading to a distortion of the tetrahedral arrangement around tin towards trigonal bipyramidal.

Short oligocytidylates can act as templates for the self-condensation of guanosine 5'-phosphorimidazolide. In the absence of a catalytic metal ion or in the presence of Pb2+ a noticeable template effect is already observed with the dimer and the yield of long oligomers reaches a plateau with a hexamer template. Short templates give oligomers longer than the template length. The products are predominantly 2'-5' linked for the Pb2+-catalyzed reaction while mixed linkages are observed in the uncatalyzed reaction. In the presence of Zn2+, a template effect is first observed with the pentamer and is maximal by the heptamer. The products are predominantly 3'-5' linked. Oligomers shorter than or as long as the template are obtained in substantial yield, and longer products in much lower yields.