V. S. Petrosyan

The effect of solvent upon the rates and mechanisms of organometallic reactions : III. nqr specta and structures of molecular complexes of methyltin halides and tin tetrahalides

Abstract NQR spectra have been obtained for molecular complexes of methyltin halides or tin tetrahalides containing various electron-donating molecules. The structures have been shown to be a function of the number of methyl groups and halogens present in the methyltin halides and of the nature of the electron donor. An anomalous temperature dependence of the NQR frequencies has been observed in some cases.

The effect of solvent upon the rates and mechanisms of organometallic reactions. : II. Molecular complexes of methyltin halides and tin tetrahalides

Methyltin halides give solid molecular complexes with the organic solvents normally employed in organometallic chemistry. Me3SnBr gives complexes of the type Me3SnBr·L with monodentate ligands (Py, DMSO, DMF, HMPT) and complexes of the type 2Me3SnBr·L with bidentate ligands (dioxane, TMED). Me2SnHal2, MeSnHal3 and SnHal4 give complexes containing either two monodentate ligands or one bidentate ligand.

The effect of the solvent upon the rates and mechanisms of organometallic reactions : V. PMR spectra and structure of molecular complexes of methyltin halides in solutions

The complexation of methyltin halides in electron-donating solvents such as acetone, dioxane, dimethoxyethane, pyridine, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and tetramethylethylenediamine has been studied by means of PMR spectroscopy. Equilibrium constants have been evaluated for Me3SnHal·D (D = donor) complexes. The concentration and temperature dependences of J(119SnC1H) in methyltin halides suggest some conclusions on the electron and spatial structures of complexes in solutions.Abstract The complexation of methyltin halides in electron-donating solvents such as acetone, dioxane, dimethoxyethane, pyridine, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and tetramethylethylenediamine has been studied by means of PMR spectroscopy. Equilibrium constants have been evaluated for Me3SnHal·D (D = donor) complexes. The concentration and temperature dependences of J(119SnC1H) in methyltin halides suggest some conclusions on the electron and spatial structures of complexes in solutions.

Tetramethyl(2-methoxyethyl)cyclopentadienyl complexes of zirconium(iv). Crystal structure of [η5:η1−C5(CH3)4(CH2CH2OCH3)]ZrCl3

Several novel zirconium(iv) complexes with the chelating oxygen-containing cyclopentadienyl ligand, tetramethyl(2-methoxyethyl)cyclopentadiene, have been synthesized. [η5:η1-Tetra-methyl(2-methyl)cyclopentadienyl]trichlorozirconium (2), bis[η5-tetramethyl(2-methoxyethyl)cyclopentadienyl]dichlorozirconium (3), [η5-pentamethylcyclopentadienyl][η5-tetra-methyl(2-methoxyethyl)cyclopentadienyl]dichlorozirconium (4), and [η5-tetra-methyl(2-methylthioethyl)cyclopentadienyl][η5-tetramethyl(2-methoxyethyl)-cyclopentadienyl]dichlorozirconium (5) have been prepared from the corresponding lithium cyclopentadienide (l). The crystal structure of cyclopentadienyl complex2 has been established by X-ray analysis. The coordination O→Zr bond in compound2 exists both in the crystalline state and in solutions. No coordination of this type was observed in complexes3–5. Synthesized complexes2–5 are discussed in comparison with their sulfur-containing analogs.

Alkyl derivatives of platinum and rhodium as intermediates in homogeneous reactions of olefin hydrogenation and isomerisation

Abstract Literature data and results obtained on the mechanisms of olefin hydrogenation and isomerisation using platinum and rhodium complexes, in particular, with PtSn and RhSn bonds were analysed. The role of alkyl derivatives of platinum and rhodium in these reactions is discussed.

The effect of the solvent upon the rates and mechanisms of organometallic reactions: VI. The complexation of dibenzylmercury in solutions studied by PMR spectroscopy

Abstract The concentration and temperature dependence of J(119HgC1H) values for solutions of dibenzylmercury in various solvents show dearly that if the solvent is of the monodentate electron-donating type 1 1 complexes are formed predominantly, the 1 2 complexes existing only at very low temperatures. The results suggest that the 1 1 complexes are very weak and have planar T-shaped structures, whereas the 1 2 complexes are probably tetragonal pyramids. In complexes of the former type the relative content of s-electrons in the HgCH site is higher than in the 1 2 complexes.

Rearrangement of silatranyl- and 3,7,10-trimethylsilatranyloxiranes to silatranylaldehydes and the crystal structure of silatranylacetaldehyde

Abstract Silatranylacetaldehyde N(CH 2 CH 2 O) 3 SiCH 2 CHO and 3,7,10-trimethylsilatranylacetaldehyde N(CH 2 CHMeO) 3 SiCH 2 CHO were prepared in high yields by rearrangement of the corresponding silatranyloxiranes N(CH 2 CHRO) 3 Si CHCH 2 O (R  H, Me), with triethylbromostannane as a catalyst. An X-ray diffraction study of the parent silatranylacetaldehyde revealed the presence, along with the expected silatranylaldehyde, of some of the starting material silatranyl ethylene. Refinement of an appropriate disorder model for C 6 H 12 NO 3 Si (CH 2 CHO) 0.75 (CH 2 ) 0.25 led to R / wR = 0.061/0.046.

The effect of the solvent upon the rates and machanisms of organometallic reactions: VII. A 19F NMR study of complexation of CF3 HgX (X = Cl, I, OCOCF3)

Abstract The concentration and temperature dependence of J ( 199 HgC 19 F) for solutions of CF 3 HgX (X = Cl, I, OCOCF 3 ) in various solvents shows that in inert solvents these molecules exist mainly as non-solvent dimers (X = I or OCOCF 3 ) or as monomers (X = Cl). In strongly coordinated solvents 1 2 complexes are largely formed from CF 3 HgX and the electron-donating solvent molecules. In pyridine solution an equilibrium exists between the 1 1 and 1 2 complexes. Complexes of the type CF 3 HgX·D are T-shaped and have a higher relative content of s -electrons in the HgCF group compared with tetrahedral CF 3 HgX·2D complexes.

Synthesis of silatranyl- and 3,7,10-trimethylsilatranyl-cyclopropanes

Treatment of silatranyl- and 3,7,10-trimethylsilatranyl-ethylenes with diazomethane/Pd(OAc)2 gives the corresponding silatranylcyclopropanes in high yields.

Cis- and trans-influences in octahedral complexes of methyltin trihalides and tin tetrahalides with tertiary phosphines

Abstract By analysis of 1 J ( 119 Sn 31 P) coupling constants for complexes of methyltin trihalides and tin tetrahalides with mono- and bi-dentate tertiary phosphines, it is proposed that strengthening of the SnP bonds occurs when the phosphine is situated in a trans -position to the most electron-donating substituent, and it is accompanied by a concomitant weakening of the cis -SnP bond.