Paramagnetic complexes carbon monoxide reactions

The kinetics of the photoeatalytic reduction of NO by CO to CO2, N2O, and N2 over MoOa/Si02 catalysts at ambient temperature has been studied mass-spectroscopically using C labeled carbon monoxide. The kinetic data obtained for CO-NO mixtures of different compositions fit well the proposed redox mechanism, which suggest a paramagnetic complex (Mo ". ..NO ") as reaction intermediate. The formation of this complex is proven by EPR experiments. 

In our previous publication [6], we have reported for the first time on the photocatalytic reduction of NO by carbon monoxide over a Mo03/Si02 catalyst (2.5 wt % of Mo). The reduction proceeds under UV-irradiation (X < 360 nm) at ambient temperature, N2, N2O, and CO2 being the reaction products. A redox reaction mechanism was proposed in [6] consisting of two st es (a) photoinduced reduction of the initial surface Mo to Mo by CO and b) dark oxidation of Mo by NO to yield N2O and N2 and to restore Mo. Both stages can be accomplished separately or combined in one photocatalytic process. A Mo-nitrosyl paramagnetic complex was suggested to be an intermediate in the photocatalytic NO reduction by CO. 

Cu(II) to yield a paramagnetic Cu(II)-thiolate complex/ Carbon dioxide coordinated to Ni(0) may be reduced to CO by R—SH (R = H, alkyl, benzyl, phenyll, or substituted phenyl) providing a model for carbon monoxide dehydrogenase enzyme. The disulfide generated in this reaction reacts further with the Ni(0) complex to give Ni(SR)2/ The kinetics of the reduction of Cr(VI) by l-methionine (represented by RSCH3) provides the rate law (45), with values for /c2... 

Most quinones, instead of forming rr complexes, react with nickel carbonyl yielding salt like materials. With p-benzoquinone, for instance, a nearly black, insoluble, hydroscopic and paramagnetic (ja f = 3.3 B.M.) material of composition Ni(quinone)2 was obtained which is best formulated as Ni (quinone)2 and considered as a metallic quinhydrone type of compound 54). However, duroquinone behaves exceptionally. In a smooth reaction all four molecules of carbon monoxide are evolved and red, crystalline, diamagnetic bis(duroquinone)-nickel (XX) (54) is obtained. This complex is stable in air and begins to decompose without melting at 205° C. It is nearly insoluble in all solvents except dichloromethane, in which it is monomeric. In the infrared spectrum, the quinone C=0 stretching frequency appears at 1577 cm (in free duroquinone it is 1629... 

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