Trialkylphosphine molecule

Nickel(II) complexes containing up to four molecules of trialkylphosphines have been prepared by the direct reaction of a nickel(II) salt with the appropriate phosphine in either aprotic or protic solvents. Anaerobic conditions have sometimes been employed in order to avoid oxidation of unstable phosphines whereas dimethoxypropane has occasionally been employed as a dehydrating agent when using hydrated nickel(II) salts. 

Splitting of a Water Molecule by Trialkylphosphine Complexes of Platinum and Rhodium and Its Chemical Applications... 

With chromium, molybdenum, and tungsten carbonyls, 1 and 2 displace two CO molecules and form the trans complexes, (l)2M(CO)4 and (2)2M(CO)4 (M = Mo, Cr and W). As an example, the structure of (l>2Cr(CO)4 is shown in Fig. 6. To provide a measure of the strength of these ligands as electron donors, the C=0 stretching frequencies for these complexes were determined by IR spectroscopy [9]. The frequencies for the molybdenum complexes, and for a number of isostmctural Mo compounds, are shown in Table 1. The data indicate that toward Mo(CO)4 as a reference acid, 1 is about equal to triphenylphosphine in donor ability, whUe 2 is slightly weaker, more resembling a trialkoxyphosphine. The stable carbene isostmctural with 1 is an extremely powerful Lewis base toward molybdenum, however, surpassing even trialkylphosphines. 

Recent developments on acidity characterization of solid acid catalysts, specifically those invoking P solid-state nuclear magnetic resonance (SSNMR) spectroscopy using phosphorus-containing molecules as probes, have been summarized. In particular, various P SSNMR approaches using trimethylphosphine, diphosphines, and trialkylphosphine oxides (R3PO) will be Introduced, and their practical applications for the characterization of important qualitative and quantitative features, namely, type, distribution, accessibility (location/proximity), concentration (amount), and strength of acid sites in various solid acids, will be illustrated. 

Following the arguments mentioned earher, phosphorus-containing molecules, such as TMP and trialkylphosphine oxides (R3PO), should be more desirable as NMR probes. This is owing to the fact that, like H... 

Besides trialkylphosphine oxide (R3PO) molecules, PPhs (11.7 X 7.1 A) [30] has also been applied to probe acid sites in solid acid catalysts. Separate study using molecular mechanical simulations has revealed that the pyramidal shape PPh3 molecule prefers to adsorb on the 12-MR external surface pockets (7.1 X 9.2 A) of the MCM-22 zeolite through partial intrusion (see Fig. 2.33) [77] and is hence only capable of probing acid sites in the external surface pockets. The P MAS NMR spectrum of PPhs adsorbed... 

The derivatization of IPDI is easier to accomplish because of the different reactivities of the two isocyanate groups in the molecule. For example, preferential dimerization of the primary isocyanate group is observed in the trialkylphosphine-catalyzed reaction (46). Trimerization of IPDI in the presence of quaternary ammonium salts affords mainly the isocyanurate trimer (47). Attempted biuret formation from IPDI and Na2S04 IOH2O gives a mixture of ureas and biurets (48). A biuret derivative is also obtained from IPDI and HDA (49). 

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