High-pressure infrared spectroscopy

QH )2PCH2P(QHii)2], 120, with CO, the intermediate bimetallic complex 121 could be detected by in situ P HP NMR (Figure 1.42) [247]. Previous attemps to detect 121 by high pressure infrared spectroscopy had proven unsuccessful [248]. 

The Use of High Pressure Infrared Spectroscopy to Study Catalytic Mechanisms... 

I 3 The Use of High Pressure Infrared Spectroscopy to Study Catalytic Mechanisms 3.3.2.3 Exchange between Rh-D and H2... 

Other studies by high-pressure infrared spectroscopy under conditions similar to those used for catalytic CO hydrogenation have been reported by Whyman (50). At 150°C and 290 atm of 1 1 H2/CO in heptane solution the equilibrium... 

Studies of I /Ru stoichiometry previously discussed and shown in Fig. 20 suggest that these two complexes, or at least a catalyst composition of the same stoichiometry, are present during catalysis. Studies of active solutions during catalysis by high-pressure infrared spectroscopy have also confirmed the presence of these complexes (191). Under 544 atm of H2/CO at 230°C in sulfolane solvent, the infrared absorptions for the carbonyl ligands of both complexes are observed clearly. No other carbonyl absorptions are evident. Samples have also been withdrawn from catalytic reactions and cooled immediately to low temperature before analysis by infrared spectroscopy these solutions also are found to contain only [HRu3(CO)j J and [Ru(CO)3I3]. ... 

Hoveyda-types, supported, in olefin metathesis, 12, 716 HP-IR, see High-pressure infrared spectroscopy HP-NMR, see High-pressure nuclear magnetic resonance HTL, see Hole-transporting layer... 

In the decades following the identification of the stoichiometric cobalt binuclear elimination reaction by Heck and Breslow, a number of researchers set out to verify the catalytic analogue. In particular, Whyman [35, 36], Alemdaroglu et al. [37] and Mirbach [38] conducted in situ spectroscopic analyses using high-pressure infrared spectroscopy. All groups observed the simultaneous presence of the mononuclear species HCo(CO)4 and RCOCo(CO)4 with simple alkenes (i.e. R = octyl, cyclohexyl) and the dinuclear complex Co2(CO)g under catalytic alkene hydrofor-mylation conditions. The general conclusion from Whyman and Mirbach was that... 

Haynes A (2005) The use of high pressure infrared spectroscopy to study catalytic mechanisms. In Heaton B (ed) Mechanisms in homogeneous catalysis a spectroscopic approach. Wiley, Weinheim, pp 107-150... 

The form and phase of the active catalyst in all of the examples above for liquid-phase carbonylation remain in some doubt. Rates and selectivities appear to be generally similar to the homogeneous system, but there are few comparative data. Convincing evidence for catalyst immobilization under liquid-phase conditions is currently lacking for carbon and zeolite supports. Such evidence could be provided by continuous flow experiments, by direct sampling vmder reaction conditions, or by using in situ techniques such as high pressure infrared spectroscopy in a batch reactor study. 

Chang, H. -C., Jiang, J. -C, Liou, Y. -C, Hung, C. -H., Lai, T. -Y., Lin, S. -H. (2008c) Local Structures of Water in l-Butyl-3-methylimidazolium Tetrafluoroborate Probed by High-Pressure Infrared Spectroscopy, ASet. Vol. 24 1305-1309. 

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