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The oxidative addition reaction of ditellurides R₂Te₂ [R = ⁿBu, Ph, Th (2-thienyl, C4H3S)] to [Pt(η²-nb)(dppn)] (nb = norbornene, dppn = 1,2-bis(diphenylphosphano)naphthalene) was found to afford [Pt(TeR)₂(dppn)] [R = ⁿBu (1), Ph (2), Th (3)] and [Pt(TeR)(R)(dppn)] [R = Ph (4), Th (5)] as a result of the cleavage of the Te-Te or C-Te bond, respectively. The reactions and the product distributions were monitored by 31P{1H} NMR spectroscopy. The spectral interpretation was assisted by the high-yield preparation of [Pt(TePh)₂(dppn)] (2) and [Pt(TeTh)₂(dppn)] (3) by ligand exchange reactions from [PtCl₂(dppn)], and by the crystal structure determinations and spectral characterizations of 2 and 3. Two series of reactions were carried out both at room temperature and at −80 °C. One involved the addition of the toluene solution of R₂Te₂ to that of [Pt(η²-nb)(dppn)], and the other the addition of [Pt(η²-nb)(dppn)] solution to the R₂Te₂ solution. The oxidative addition of ⁿBu₂Te₂ to [Pt(η²-nb)(dppn)] yielded solely [Pt(TenBu)₂(dppn)]. In case of Ph₂Te₂ and Th₂Te₂, the reaction of equimolar amounts of ditelluride and [Pt(η²-nb)(dppn)] afforded only [Pt(TeR)(R)(dppn)] (R = Ph, Th), but when an excess of R₂Te₂ was used, the addition of [Pt(η²-nb)(dppn)] to the ditelluride resulted in the formation of a mixture of [Pt(TeR)₂(dppn)] and [Pt(TeR)(R)(dppn)] with the latter the main component. An excess of R₂Te₂ and the lowering of the temperature favoured the formation of [Pt(TeR)₂(dppn)]. The reaction energetics in toluene was calculated at revPBE/def2-TZVP(-f) level of theory. The increase of the electron withdrawing nature of the organic substituent rendered [Pt(TeR)(R)(dppn)] increasingly stable with respect to [Pt(TeR)₂(dppn)]. The computation of the energy profiles of the likely pathways of the oxidative addition indicated that concurrent formation of [Pt(TeR)₂(dppn)] and [Pt(TeR)(R)(dppn)] (R = Ph, Th) may be more likely than the formation of the latter due to the de

The iridium(I) complexes [IrCl(Me2PhP)3] (1), [Ir(Me2PhP)4]Cl (2), [Ir(Me2PhP)4]I (3), and [Ir(Me2PhP)4]PF6 (4) are prepared from the iridium(I) precursors [IrX(coe)2]2 (X = Cl, I). Complex 1 reacts reversibly with CO2 to form the metallacyclic compound [IrCl(C2O4-k2C,O)(Me 2PhP)3] (5), which was characterized by NMR and IR measurements as well as elemental analysis. Additionally, [mer-Ir(Cl) 2(H)(Me2PhP)3] (6) and [mer-Ir(CO 3)(H)(Me2PhP)3] (7) are formed as side products from water present in the used CO2 and the solvents. Compound 2 yields similar results. When the iodo compound 3 is used, the cationic compound [Ir(I)(H)(Me2PhP)4]+I- (9) is formed as one of the products. Molecular structures of 1, 2, 5, and 9 are presented. © 2010 American Chemical Society.

The reaction of 1,1-bisdiphenylphosphinomethane (dppm, 4 eq.) with [IrCl(coe)2]2 results in a solvent dependent equilibrium from which the complexes [IrCl(dppm)(dppm-H)(H)] (1) and [Ir(dppm) 2]Cl (2) were isolated. When 2 is dissolved in methanol, [IrCl(dppm)2(H)][OCH3] (4) is formed as dominant species in solution. The C-H activation reaction which leads to 1 and 4 can be suppressed by adding an additional dppm ligand per iridium center resulting in the formation of [Ir(dppm)3]Cl (5). If the reaction of dppm with [IrX(coe)2]2 (X = Cl, I) is performed under an atmosphere of CO2 the complexes [IrX(dppm)(H){(Ph2P) 2C-COOH}] (6: X = Cl; 7: X = I) are formed by a CH activation/CO 2 carboxylation sequence. The reaction of 6 with NH4PF yields [IrCl(dppm)2(H)]PF6.(10). Additionally the lithium compounds [Li(dme)2(dppm-H)] (3) and [Li(dme){(Ph2P) 2CHCOO}]2 (8) were prepared for comparison. The molecular structures of the compounds 1, 3, 5, 7, 8 and of the related iridium complex [IrCl(dppm)2(H)]I (11) are reported. © The Royal Society of Chemistry 2010.

Background There are many nucleoside metal complexes known. According to observations made, only very few of them reveal their central ion to be co-ordinated by the sugar part of their molecules. The regio- and stereospecific exchange of the hydroxyl groups at the sugar moiety by chelating units improves its complexation ability and should give access to a new class of chiral ligands. Results In this paper we present the synthesis of 3',5'-diamino substituted thymidines with ribo- as well as xylo-configuration and the preparation of copper(II) complexes derived from their corresponding Schiff bases. Starting from thymidine, the amino derivatives were prepared in a three and four step reaction sequence respectively. The absolute configuration of the ligands was proved by the three-bond 1H-1H spin spin coupling constants 3J obtained by NMR-studies. Condensation of the amino derivatives with salicylic aldehydes resulted in the corresponding diimines, which represent a new class of chiral salen-type ligands. All ligands formed uncharged stable copper(II) complexes. The structure of 3',5'-bis(3,5-di-tert-butylsalicylaldiminato)-3',5'-dideoxyxylothymidine-copper(II) could be determined by single crystal X-ray structure analysis. The copper centre in this complex has distorted tetrahedral coordination geometry. Conclusion For the synthesis of 3',5'-diamino-3',5'-dideoxy thymidines with xylo- as well as ribo-configuration an effective synthesis pathway has been developed. Their corresponding salicylidene imines form stable coordination compounds with copper(II) ions. They represent the first salen type complexes of nucleosides with this substitution pattern., Applied Sciences

A series of novel S,N-heterocyclic (thiazolyl) substituted carboximidamides 3 and 4 was synthesized in yields up to 82% from specific triazinium salts 1 and primary or secondary amines 2 which additionally bear pyridine or imidazole units. These carboximidamides are used as tailor-made ligands for the complexation of Cu(II) and Zn(II). The coordination behavior of 3 and 4 and the properties of the resulting metal complexes are affected a significant extent especially by the nature of these amine substituents. The most important structural feature of the novel complexes is that the ligation of the metal cations is achieved by a 1,3,5-triazapentadienyl anion system, compare the X-ray structure of the model complex Cu-4d. Analogous Zn(II) complexes 5, 6a, 6b, 6c, 7a, and 7b were obtained from carboximidamides 3, 4a, 4b, 4c, 4d, and 4e after reaction with diethylzinc. Interestingly, these Zn(II) complexes possess an intrinsic activity to catalyze the copolymerization of cyclohexene oxide and carbon dioxide to give polycarbonates 15 (TON up to 113; Turn Over Number: moles of substrate 14 consumed per moles of zinc. Molecular weights: up to 206â103 Da). Contaminations of 15 by polyethers are produced only in remarkably small amounts.

Starting with bis([1,3,4]thiadiazolo)[1,3,5]triazinium halides 1, a novel class of heterocyclic compounds, the [1,3,4]thiadiazolo[2,3-d][1,2,4]triazolo[1,5-a][1,3,5]triazinium halides 5 were prepared. The reaction between 5 and primary or secondary amines 6 yielded highly substituted guanidines 8 and fused tricyclic bis([1,2,4]triazolo)[1,5-a:10,50-d][1,3,5]triazinium halides 9. The formation of the reactive triazinium-imidothioate zwitterions 7, which is controlled by the influence of negative hyperconjugation, was proven by NMR data and the X-ray structure of 7c. The subsequent ring-closure/ring-opening steps can be understood in terms of an SN(ANRORC) process accompanied by intramolecular proton-transfer reactions. The zwitterions 7 were reacted with EtI forming cationic derivatives 10 or hydrolyzed at pH 6–7 to give novel heterocyclic ethanethioamide 11.