219815-69-7Relevant academic research and scientific papers
Olefin complexes of low-valent rhenium
Choualeb, Aldjia,Blacque, Olivier,Schmalle, Helmut W.,Fox, Thomas,Hiltebrand, Thomas,Berke, Heinz
, p. 5246 - 5261 (2008/03/18)
Replacement of the MeCN group in the acetonitrile-cis-dibromo(nitrosyl)- trans-bis(phosphane)rhenium compounds 1a,b (R = iPr a, R = Cy b) with ethylene afforded the olefin derivatives [Re(η2-H2C=CH 2) (NO) (PR3)2Br2] (2a,b) (R = iPr a, R = Cy b). Compound 1a could be converted into the dimethyl species [Re(MeCN)(NO)(PiPr3)2Me2] (3a) applying MeLi in toluene; the related methylation of 1b, however, failed. Abstraction of a Br- ion from 1a,b with [Na][BAr′4] in acetontrile yields the air-stable salts [Re(MeCN)2(NO)(PR3) 2Br]+[BAr′4]- (4a,b) (R = iPr a, R = Cy b) and under 1 bar of H2 complexes 1a,b were converted into the known dihydrogen species [Re(η2-H2)(NO)(PR 3)2(Br)2] (5a,b) (R = iPr a, R = Cy b). Reduction of [Re(MeCN)(NO)(PR3)2Br2] (1a,b) with Na/Hg under 1 bar of C2H4 afforded the butadiene complex [Re(η4-C4H6)(η2- H2C=CH2)(NO)(PR3)2] (6a,b) (R = iPr a, R = Cy b) via oxidative coupling of two coordinated ethylene groups followed by double β-H shift and subsequent reductive H2 elimination from the formed dihydride complex. Reduction of the complexes [Re(CO)(NO)(PR 3)2Cl2] (7a,b) (R = iPr a, R = Cy b) with Na/Hg yields the pentacoordinate species [Re(CO)(NO)(PR3) 2(η2-H2C=CH2)] (8a,b) (R = iPr a, R = Cy b) under the same conditions as for 6a,b. Reaction of 8a with 1 equiv. of B(C6F5)3 leads to the [Re(CO) 2{NOB(C6F5)3}(PiPr3) 2] compound (9a) and to the carbonyl nitrosyl complexes [Re(CO) 2(NO)(PiPr3)2] (10a) with evolution of ethylene. The same reaction of 8a and 8b, but applying 1 bar of CO, leads to exclusive formation of 9a,b. Complexes 4a, 4b, 6b, 8a, 9a, and 9b were characterized by X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
