Dihydrogen Complexes of Rhodium: [RhH2(H2)x(PR3)2]+ (R = Cy, iPr; x = 1, 2)
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- 作者：Michael J. Ingleson ; Simon K. Brayshaw ; Mary F. Mahon ; Giuseppe D. Ruggiero ; and Andrew S. Weller
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：May 2, 2005
- 年：2005
- 卷：44
- 期：9
- 页码：3162 - 3171
- 全文大小：194K
- 年卷期：v.44,no.9(May 2, 2005)
- ISSN：1520-510X
文摘
Addition of H2 (4 atm at 298 K) to [Rh(nbd)(PR3)2][BArF4] [R = Cy, iPr] affords Rh(III) dihydride/dihydrogen complexes.For R = Cy, complex 1a results, which has been shown by low-temperature NMR experiments to be the bis-dihydrogen/bis-hydride complex [Rh(H)2(
mages/gifchars/eta.gif" BORDER=0 >2-H2)2(PCy3)2][BArF4]. An X-ray diffraction study on 1a confirmed the {Rh(PCy3)2} core structure, but due to a poor data set, the hydrogen ligands were not located. DFT calculations at theB3LYP/DZVP level support the formulation as a Rh(III) dihydride/dihydrogen complex with cis hydride ligands. ForR = iPr, the equivalent species, [Rh(H)2(mages/gifchars/eta.gif" BORDER=0 >2-H2)2(PiPr3)2][BArF4] 2a, is formed, along with another complex that wasspectroscopically identified as the mono-dihydrogen, bis-hydride solvent complex [Rh(H)2(mages/gifchars/eta.gif" BORDER=0 >2-H2)(CD2Cl2)(PiPr3)2][BArF4] 2b. The analogous complex with PCy3 ligands, [Rh(H)2(mages/gifchars/eta.gif" BORDER=0 >2-H2)(CD2Cl2)(PCy3)2][BArF4] 1b, can be observedby reducing the H2 pressure to 2 atm (at 298 K). Under vacuum, the dihydrogen ligands are lost in these complexesto form the spectroscopically characterized species, tentatively identified as the bis hydrides [Rh(H)2(L)2(PR3)2][BArF4] (1c R = Cy; 2c R = iPr; L = CD2Cl2 or agostic interaction). Exposure of 1c or 2c to a H2 atmosphereregenerates the dihydrogen/bis-hydride complexes, while adding acetonitrile affords the bis-hydride MeCN adductcomplexes [Rh(H)2(NCMe)2(PR3)2][BArF4]. The dihydrogen complexes lose [HPR3][BArF4] at or just above ambienttemperature, suggested to be by heterolytic splitting of coordinated H2, to ultimately afford the dicationic clustercompounds of the type [Rh6(PR3)6(mages/entities/mgr.gif">-H)12][BArF4]2 in moderate yield.