Rhodium halide complex

The iridium- (and rhodium-) halide complexes may be extracted as ion-pairs with DAM, diphenylguanidine or tribenzylamine [76]. The process has been used as a basis for extraction-spectrophotometric methods of Ir determination. 

Rhodium(I) complexes are effective reagents and/or catalysts for the decarbonylation of acyl halides and aldehydes 9 11,34,195,230,231,236). The compound Rh(PPh3)3Cl, especially, has received considerable attention. The first step in such reactions involves oxidative addition to Rh(I) of the organic molecule, exemplified by the following ... 

One can set up to do this using the competition between dimerization and halogen atom abstraction from RX to form the rhodium(III) halide complex. As a function of [RX], the product ratio is quite easily evaluated. From that, one can get the rate constant ratio but, knowing independently the rate constant for dimerization, it is possible to extract from those data rate constants for reactions of the rhodium(II) complex with these organic halides. The rate constants obtained are listed in Table I. 

The halide exchange protocol also allows the use of other nucleophiles such as activated methylenes. The rhodium iodide complex was found to be the most... 

Indenyl)rhodium(I) complexes, preparation, 7, 184—185 Indium complexes acid halide reactions, 9, 683 in alkene and alkyne allyindations, 9, 693 alkyl, aryl, alkynyls, 3, 288 in alkynylations, 9, 720... 

These early successes with carbonyl complexes of rhenium encouraged me to undertake systematic research on the carbon monoxide chemistry of the heavy transition metals at our Munich Institute during the period 1939-45, oriented towards purely scientific objectives. The ideas of W. Manchot, whereby in general only dicarbonyl halides of divalent platinum metals should exist, were soon proved inadequate. In addition to the compounds [Ru(CO)2X2] (70), we were able to prepare, especially from osmium, numerous di- and monohalide complexes with two to four molecules of CO per metal atom (29). From rhodium and iridium (28) we obtained the very stable rhodium(I) complexes [Rh(CO)2X]2, as well as the series Ir(CO)2X2, Ir(CO)3X, [Ir(CO)3]j (see Section VII,A). With this work the characterization of carbonyl halides of most of the transition metals, including those of the copper group, was completed. 

Few studies have been made of the reactions of this class of complex. The action of bases upon the complexes brings about reductive elimination of hydrogen halide (equation 207).973 However, if this reaction is carried out in dichloromethane it appears that the hydrido ligand reduces the solvent since, although the base hydrochloride is formed, a rhodium(III) complex results (equation 208).953 The action of bromine989 or S02953 also produces hydrogen halide (equations 209 and 210). (The reaction with concentrated nitric acid has already been mentioned in Section 48.6.3.3,ii above.953)... 

There are two monohydrido complexes which have been prepared by the oxidative addition of hydrogen halides to [Rh P(OMe)3 5][BPh4] (equation 223). Two other monohydrido complexes having hydrogen-bonded anions have been prepared by simultaneous substitution of and oxidative addition to dinuclear rhodium(I) complexes (equation 224). The anions give resonances at very low fields in the H NMR spectra of the complexes.1050 The physical properties of the monohydrido complexes are listed in Table 77. 

The other hydrogen halides add oxidatively to rhodium(I) complexes of ditertiary phosphines or arsines giving rise to numerous monohydrido complexes, whose physical properties are also listed in Table 79. However, it is possible to prepare certain monohydrido complexes from rhodium(III) halides. One interesting reaction, carried out under an atmosphere of CO, gives rise to dicar-bonyldichlororhodate(I) salts (equation 241).226... 

Probably the most numerous bimetallic complexes of rhodium are those containing mercury. The complex //-[RhHCl (AsMePh,)3 ] reacts with mercury(II) halides,1351 phenylmercury(II) halides,1352 or mercury(I) halides 351,1352 to produce/ac-rhodium-mercury complexes (145) (equation 333). The physical properties of the products are shown in Table 94. 

Finally, copper(I), silver(I), and mercury(II) triazenides react with selected rhodium(I), iridium(l), and platinum(II) halide complexes to afford metal-metal bonded binuclear triazenide-bridged species 129). 

Enolates can also be prepared by rhodinm-catalyzed isomerization of allylic Uthinm alcoholates, such as 14 (equation 5)". Subsequent treatment of the intermediately formed rhodium hydride complexes (15 and 16) with an electrophile led to the formation of various products. For example, alkyl halides gave a-alkylated ketones (17) in good yields, as shown in Table 4. Interestingly, addition of benzaldehyde under kinetically controlled... 

Delgado, F., Cabrera, A., Gomez-Lara, J. Steric and electronic influences on the reaction mechanism of the catalytic decarbonylation of acid halides in homogeneous phase using rhodium carbonyl complexes. J. Moi. Catai. 1983, 22, 83-87. 

Rhodium(lll) complexes Collaborative studies between van Eldik, Ford and coworkers have led to thorough parameterization of pressure effects on photosolvolysis of the rhodium(III) halopentaammines Rh(NH3)sX + (Eq. 6.18) [39-45]. For these systems LF excitation is followed by rapid intersystem crossing (cDisc 1) to the lowest energy LF state E from which reactive (kp), radiative (k,) and non-radiative (k ) deactivation occur competitively (Fig. 6.10) [41, 46]. Rate constants for individual excited state processes were calculated from phosphorescence quantum yields fl>r, lifetimes r and quantum yields for halide ([Pg.198]

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