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The reactivity of ylide-like phosphasilene 1 [LSi(TMS)═P(TMS), L = PhC(NtBu)2] with group 10 d(10) transition metals is reported. For the first time, a reaction of a phosphasilene with a transition metal that actually involves the silicon-phosphorus double bond was found. In the reaction of 1 with ethylene bis(triphenylphosphine) platinum(0), a complete silicon-phosphorus bond breakage occurs, yielding the unprecedented dinuclear platinum complex 3 [LSi{Pt(PPh3)}2P(TMS)2]. Spectroscopic, structural, and theoretical analysis of complex 3 revealed the cationic silylene (silyliumylidene) character of the silicon unit in complex 3. Similarly, formation of the analogous dinuclear palladium complex 4 [LSi{Pd(PPh3)}2P(TMS)2] from tetrakis(triphenylphosphine) palladium(0) was observed. On the other hand, in the case of bis(cyclooctadiene) nickel(0) as starting material, a distinctively different product, the bis(silylene) nickel complex 5 [{(LSi)2P(TMS)}Ni(COD)], was obtained. Complex 5 was fully characterized including X-ray diffraction analysis. Density functional theory calculations of the reaction mechanisms showed that the migration of the TMS group in the case of platinum and palladium was induced by the oxidative addition of the transition metal into the silicon-silicon bond. The respective platinum intermediate 2 [LSi{Pt(TMS)(PPh3)}P(TMS)] was also experimentally observed. This is contrasted by the reaction of nickel, in which the equilibrium of phosphasilene 1 and the phosphinosilylene 6 [LSiP(TMS)2] was utilized for a better coordination of the silicon(II) moiety in comparison with phosphorus to the transition metal center.

The title quinones, 2,5-bis(4-oxo-2,5-cyclohexadien-1-ylidene)-2,5-dihydrothiophene and its tetraalkyl derivatives, were synthesized via 2-(4-alkoxyphenyl) thiophene and 2,5-bis(4-alkoxyphenyl) thiophene conveniently prepared by using palladium (0)-catalyzed cross coupling reaction of 4-alkoxyaryl halides and thienylzinc chloride. The ground-state structures and redox properties of these quinones were fully characterized based on spectroscopic data (IR, 1 H NMR, 13 C NMR, UV-vis, and MS), X-ray analysis, cyclic voltammetry, CNDO/2 calculation, and EPR spectroscopic investigation

Un deplacement intramoleculaire direct de proton 1,3 est observe dans les derives du cycloheptatriene; ce deplacement s'effectuant via un carbanion ponte par une liaison hydrogene 1,3 qui est un etat de transition plutot qu'un intermediaire

Synthese et etude du comportement electrochimique de bis-[di-t-butyl-3,5 oxo-4 cyclohexadiene-1,5ylidene] ter- et quaterthiophenediylene ainsi que le derive bithiophenylidene-2,2'