Photolysis complexes

The corresponding reaction of the isomeric enamide (79) is more complex. Photolysis of this compound in methanol gives the partially demethylated cycliza-tion product (82), with the expected substitution pattern, in 65% yield, together with the desmethoxy-compound (81 R = H) (20%). In benzene, the main product of photolysis is the desmethoxy-bromo-compound (81 R = Br). The mechanism of the cyclization with loss of a methoxy-group may be represented as in structures... 

The reduction of 3,4-dichlorocyclobutene (222) in the presence of metal carbonyls has been utilized to prepare the parent complex [223, MLn = Cr(CO)4, Mo(CO)3, W(CO)3, Fe(CO)3, Ru(CO)3 orCo2(CO)6] (equation 32) .Morerecently, reaction ofNi(CO)4 with 3,4-dihalocyclobutenes (X = Br or I) or with 222 in the presence of AICI3 produced the corresponding (cyclobutadiene)nickel dihalides . Methodology for the preparation of 1,2- or 1,3-disubstituted (cyclobutadiene)Fe(CO)3 complexes from 1,2- or 1,3-disubsli-tuted-3,4-dibromocyclobutenes has been presented - In turn, the substituted dibromo-cyclobutenes are prepared from squaric esters. The reaction of cz5-3,4-carbonyldioxycy-clobutene and substituted variants with l c2(CO)9 orNa2Fe(CO)4 also produces (cyclobu-tadiene)Fe(CO)3 complexes . Photolysis of a-pyrone generates 3-oxo-2-oxabicyclo [2.2.0]hex-5-ene (224) which undergoes photolysis with a variety of metal carbonyls to afford the parent cyclobutadiene complex 223 [MLn = CpV(CO)2, Fe(CO)3, CoCp. or RhCp] (equation 33) 2 0. 

Photosynthesis schemes are available for bis(bipy)Ru(II) complexes Photolysis of [RufbipyljpyjICPFjlj in dichloromethane containing [(n-C H NjY (Y = [NOj], fciO ] , [NCS] , Cl Br , etc.) leads to the stepwise replacement of pyridine to form isolable quantities of the mono ... 

As seen for Co(IIl) complexes, photolysis of disubstituted Rh(III) and Ir(lll) tetraammines often leads to photoisomerizations concomitant with ligand labilization, e.g. ... 

Photosubstitution chemistry dominates in Fe isocyanide complexes . Photolysis ... 

Photosubstitution chemistry dominates in Fe isocyanide complexes . Photolysis of aq Fe(CNCH3)J2+ gives [Fe(CNCH3) (HjO)3E+-... 

Photosynthesis schemes are available for bis(bipy)Ru(II) complexes". Photolysis of... 

But does the photodecomposition of pesticides really take place in the aquatic world Are light-energized transformations of pesticides environmentally important Unfortunately, almost no incontrovertible evidence has been reported. The complex photolysis products of PCP found in rice-paddy water (46) (Figure 6) are sufficiently unusual to make a case, and the sunlight photolysis of diquat (6,7-dihydrodipyrido[l,2-a 2, l -c]pyrazindiium chloride) on plants and in water is so rapid that again the presence of its photolysis products in field samples is to be expected (58). Few other examples are known. 

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