Redistribution of reduced thiophene ligands in the conversion of (C{sub 5}R{sub 5})Rh({eta}{sup 4}-C{sub 4}Me{sub 4}S) to [(C{sub 5}R{sub 5})Rh]{sub 3}({eta}{sup 4}, {eta}{sup 1}-C{sub 4}Me{sub 4}S){sub 2}
- Univ. of Illinois, Urbana, IL (United States)
The thermal decomposition of (C{sub 5}Me{sub 5})Rh({eta}{sup 4}S) (1) has been examined by spectroscopic, kinetic, and structural studies. Compound 1 cleanly eliminates free C{sub 4}Me{sub 4}S to give [(C{sub 5}Me{sub 5})Rh]{sub 3}({eta}{sup 4}, {eta}{sup 1}-C{sub 4}Me{sub 4}S){sub 2} (2a). The structure of the analogous compound [(C{sub 5}Me{sub 4}Et)Rh]{sub 3}({eta}{sup 4}, {eta}{sup 1}-C{sub 4}Me{sub 4}S){sub 2} (2b) conists of a pair of (C{sub 5}Me{sub 4}Et)Rh({eta}{sup 4}-C{sub 4}Me{sub 4}S) ligands bound to a central (C{sub 5}Me{sub 4}Et)Rh{sup 1} unit through the sulfur atoms. The conversion of 1 to 2a occurs via a second-order process (in rhodium) with k(60 {degrees}C) = 3.94 x 10{sup -4} M{sup -1}M{sup -1}{center_dot}s{sup -1} which implicates an associative mechanism. Activation parameters are {Delta}H{sup {double_dagger}} = 20.1 {plus_minus} 0.1 kcal/mol and {Delta}S{sup {double_dagger}} =-13.9 {plus_minus} 3.1 cal/mol-K. Dynamic {sup 1}H NMR studies demonstrate that 2a maintains its structure in solution but that it experiences restricted rotation about the two Rh-S bonds. Compound 2a decomposes via a first-order process with k(100 {degrees}C) = 8.94 x 10{sup -6} s{sup -1} to give (C{sub 5}Me{sub 5}){sub 2}Rh{sub 2}C{sub 4}Me{sub 4}S, 3. 20 refs., 4 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 563465
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 5 Vol. 114; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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