Synthesis, Structure, and Hydrophosphorylation of π-Complexes of Hexacarbonyltungsten(0) with Cyclohexanone, Cyclohexanethione, and N-Cyclohexylideneaniline

Abstract

New carbonyl π-complexes of tungsten(0) with cyclohexanone, cyclohexanethione, and N-cyclohexylideneaniline were synthesized. Geometric and electronic parameters of the ligands, as well as energy parameters of the complex formation process, were determined by quantum-chemical calculations. Hydrophosphorylation with diethyl phosphonate changed the reactivity of coordinated N-cyclohexylideneaniline, while no analogous effect was observed for cyclohexanone and cyclohexanethione.An actual problem of modern chemistry is selective functionalization of compounds possessing several potential reaction centers; solution of this problem makes it possible to develop procedures for targetoriented synthesis of polyfunctional organic and organometallic compounds with a specified structure. A promising method for design of new organophosphorus compounds is based on hydrophosphorylation reactions involving multiple carbon-heteroelement bonds in α,β-unsaturated oxo, thioxo, and imino derivatives. These reactions lead to formation of the corresponding unsaturated α-hydroxy, α-amino, and α-sulfanyl phosphonates which attract interest from the viewpoint of their practical applications. In addition, they are convenient intermediate products for further modifications [1]. However, the synthesis of such compounds is often complicated due to competition between carbon-carbon and carbon-heteroelement bonds in the hydrophosphorylation processes [1-4].Chemo-and regioselectivity in reactions of polyenes and heteropolyenes may be controlled via their functionalization within the coordination sphere of organometallic compounds [5]. We previously reported that oxo, aza, and thioxo dienes coordinated to zerovalent chromium subgroup metals take up dialkyl phosphonates at the double carbon-heteroelement bond, regardless of the mode of heterodiene coordination to the metal center [4, 6-8]. On the other hand, phosphorylation of unsaturated compounds as free ligands follows mainly the Pudovik scheme: P-H compounds add as a rule at the carbon-carbon bond. Our studies on numerous η x -heterodiene complexes with various x values showed that the reasons for change in the reactivity of heteropolyenes coordinated to a transition metal include not only steric factors (shielding of a potential reaction center by the metal-ligand moiety) but primarily variation of the electronic structure of the ligand due to its coordination to metal. First of all, this is distortion of conjugation in the heterodiene system of unsaturated ketones and their analogs within the coordination sphere of transition metals, as was confirmed by the results of nonempirical quantumchemical calculations [9].In the present work we examined variations in the geometric and electronic structure of unsaturated systems possessing double carbon-oxygen, carbon-sulfur, and carbon-nitrogen bonds due to their coordination to metal complexes. We also studied the effect of coordination with metals on the reactions of the ligands with diethyl phosphonate. The study was performed using IR spectroscopy...

One Pot Synthesis of tetrahydroquinoline-5-thiones and Evaluation of their Antimicrobial Activities

“…15,16 The structures of 2a-d were confirmed by spectroscopic data and elemental analyses. EI-MS gave molecular ion peaks related to the molecular weight of the suggested structures.…”

“…The formation of compounds 2a-d is emphasised by the precedence of the activity of sulfur atom in the oxidation under acidic conditions. 15,16 The structures of 2a-d were confirmed by spectroscopic data and elemental analyses. EI-MS gave molecular ion peaks related to the molecular weight of the suggested structures.…”

Synthesis of Mesityl Oxide π-Complexes with Metals of Chromium Subgroup and with Iron. Theoretical and Experimental Investigation of the Ligand Dissociation Energy

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