Rhodium photochemistry

Like the ammines, rhodium complexes of ligands like bipy and phen have a significant photochemistry. Therefore, on irradiation, solutions of cw-[Rh(L-L)2X(H20)]2+ (X = halogen) gradually convert to c/s-[Rh(L-L)2X(H20)]2+, though much more slowly than with the ammines [101]. 

Ihmels H, Otto D (2005) Intercalation of Organic Dye Molecules into Double-Stranded DNA - General Principles and Recent Developments. 258 161-204 lida H, Krische MJ (2007) Catalytic Reductive Coupling of Alkenes and Alkynes to Carbonyl Compounds and Imines Mediated by Hydrogen. 279 77-104 Imai H (2007) Self-Organized Formation of Hierarchical Structures. 270 43-72 Indelli MT, Chiorboli C, Scandola F (2007) Photochemistry and Photophysics of Coordination Compounds Rhodium. 280 215-255 Indelli MT, see Chiorboli C (2005) 257 63-102 Inoue Y, see Borovkov VV (2006) 265 89-146 Ishii A, Nakayama J (2005) Carbodithioic Acid Esters. 251 181-225... 

Fischer-type carbenes, 8, 218 iV-heterocyclic carbenes, 8, 219 non-heteroatom carbenes, 8, 217 overview, 8, 197—268 photochemistry, 1, 252 with Re(I), 5, 900 with rhodium, 7, 184 rotation, dynamic NMR studies, 1, 420 in Ru and Os half-sandwich preparations, 6, 575 silver-catalyzed insertions, 9, 568 with silver(I), 2, 203 as spectator ligands, 1, 66... 

Table 6, entry 48) whereas alkene isomerization is very slow [52]. Photochemistry is also used in the rhodium-catalyzed alkylborylation of alkanes in which boroalk-anes (Table4, entry 49) are obtained [53], An example of a gas-phase reaction is the photochemical mercury-catalyzed hydroxymethylation of cyclohexane to hydroxymethylenecyclohexane (Table 6, entry 50). This reaction is an example of the abstraction of a hydrogen atom from an alkane by an excited metal atom [54]. 

The synthesis and photochemistry of related rhodium(lll) bis(alkyl) complexes cA,cA-[Rh(R)2(I)(CO)(dmb)] (R = Me, Tr) have been studied. The complexes showed an IT (tv - r (dmb)) absorption band at ca. 295 nm. There was another band at ca. 370nm for both complexes, which was assigned to an XTCT (p(l)7r (dmb)) transition. Irradiation of both complexes in solution resulted in Rh-R bond homolysis, as evidenced by IR, UV-vis, and spin-trap EPR investigations. The photoreaction was proposed to occur after crossing from the XLCT state to the reactive SBLCT state. 

Reviews have appeared of the photophysics of molybdenum complexes, primary and secondary processes in organometallic chemistry, flash photolysis of Pe(CO)5 and Cr(CO)g, dinuclear manganese carbonyl compounds, the photochemistry of metal complexes isolated in low temperature matrices, cluster complexes, diene complexes, photoproduction of coordinativeiy unsaturated species containing rhodium or iridium, and redox chemiluminescence of organometallic compounds.Synthetic and metal organic photochemistry in industry has also been reviewed. 

Ruthenium complexes used to lead research in photochemistry of metal compounds, but rhodium complexes have recently overtaken them as the key target compounds due to their applications in OLEDs. This is a lively and ever-changing field for example, over 90% of luminescent iridum(III) complexes have been reported only in the six years to the beginning of 2009. With their luminescence tuneable through ligand choice, iridium complexes are firm candidates for optical display applications. 

Although sensitizer/relay/catalyst schemes have become very popular, alternative approaches exploiting homogeneous photochemistry are being studied. Reactions in which radical ions or carbanions are generated by illumination have been discussed, and the interesting properties of polynuclear rhodium... 

Rhodium and Iridium.—Ford16 has discussed the deficiencies of the ligand-field model for d9 systems14 when applied to RhUI photochemistry. In particular he criticizes (i) the neglect of possible variations in the efficiency of radiationless processes in estimating the relative quantum yields for the reactions of the photo-excited states and (ii) the use of crystal-field parameters derived from the ground-state configuration. 

Further Studies of the Spectroscopic Properties and Photochemistry of Binuclear Rhodium(I) Isocyanide Complexes... 

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