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7729195 
Journal Article 
pi-Olefin-iridium complexes .24. Photoreactions of [CpM(C2H4)(2)] (M = Rh, Ir) with alkynes - Good source of new pi-complexes 
Muller, J; Akhnoukh, T; Gaede, PE; Guo, AL; Moran, P; Qiao, K 
1997 
Yes 
Journal of Organometallic Chemistry
ISSN: 0022-328X
EISSN: 1872-8561 
Elsevier 
541 
1-2 
207-217 
German 
WOS:A1997YA93500023 
UV irradiation of [CpRh(C2H4)2] in pentane in the presence of alkynes C2R2 [R = Me (a); Et (b)] gives a variety of products, and several compounds have been isolated by chromatography. The η4-benzene complexes [CpRhC6R6] (2a,b) and the rhodacyclopentadienyl species [Cp2Rh2C4R4] (3a,b) were obtained as main products. The isolable but highly reactive complexes [CpRh(C2H4)(C2R2)] (1a,b) act as precursors for 3 and for hexaalkylbenzene, and by hydrolysis during chromatography also give the 1-rhoda-2-oxa-cyclohexa-3,5-diene compounds [Cp2Rh2C4R4O] (6a,b). Further isolated products are the bis(μ-vinyl) compound [Cp2Rh2(C2H3)(C2HMe2)] (4a) as well as the η4-butadiene species [CpRh{C4HR4-C5H4Rh(C2H4)2}] (5a) the formation of which involves the unusual C-H activation of a Cp moiety. From the reaction mixture formed by UV irradiation of [CpIr(C2H4)2] in hexane only the μ-vinyl species [Cp2Ir2(C2H3)2] (7) was isolated, while irradiation in the presence of butyne-2 yielded the η4-hexamethylbenzene complex [CpIrC6Me6] (8). The compounds 2b, 3b, 5a, and 8 were characterised by X-ray crystal analysis. 
rhodium; iridium; alkynes; photochemistry; x-ray crystallography