Photoinduced linkage isomerism

In recent years, the photoinduced linkage isomerization reactions of bound nitrosyl appearing in different complexes have been... 

Figure 32 Proposed mechanism for photoinduced linkage isomerization reactions of toluene solution of (TPP)Mn(ONO) (8). Reproduced with permission from Ref. (8). Copyright 2010 American Chemicai Society.

In recent years, the investigation of photoinduced linkage isomerism has become intrinsically hnked to the new method of photocrystallography [17]. Photocystallography is a rapidly developing technique that enables the full three-dimensional structure of a molecule, in a crystalhne environment, to be determined by X-ray crystallography when the molecule has been photoactivated into a shortlived excited state. Similarly, X-ray absorption (XAFS) can be used to provide structural details of excited state molecules in the solid state or in solution. In the... 

Photoinduced linkage isomerization of cobalt(III) ammine complexes has also been observed when one of the ligands is ambidentate. These reactions are shown in generalized form in Eq. (2.21). Two such examples that have received attention are the photoinduced isomerization of the thiocyanate and the nitrite ligands [Eqs. (2.22) and (2.23)] ... 

Naumov, P., Makreski, P. and Jovanovski, G. (2007) Direct atomic scale observation of linkage isomerization of As4S4 clusters during the photoinduced transition of realgar to pararealgar. Inorganic Chemistry, 46(25), 10624-31. 

Bitterwolf has studied the effects of Hght on linkage isomerization in some metal (Mn, Re) cylopentadienyl dicarbonyl nitrosyls of the form [CpM(CO)2(NO)] (M = Mn, Re) and [(MeCp)Mn(CO)2(NO)] ( 5 i . Figure 9 shows the complexes that were investigated and illustrates how the photoinduced products were generated. In a typical experiment, the sample was dissolved in a triethyloctylammonium hexafluorophosphate solution and frozen to ca. 90 K in a glass cryostat and the IR of the sample... 

Unlike (TPP)Mn(NO), the five-coordinate (TPP)Mn(ONO) complex undergoes linkage isomerization to (TPP)Mn(N02) following laser flash photolysis of a toluene solution of (TPP)Mn(ONO) (i66). The proposed mechanism involves the photoinduced dissociation of the axial ligand to (TPP)Mn and NO2. (TPP)Mn andN02 then recombine to form (TPP)Mn(N02). The latter complex readily isomeiizes back to the structurally characterized ground state (TPP)Mn(ONO) compound (Figure 32) (48). 

Scheme 3 Photoinduced cis-trans isomerization of complexes with C = N linkages...

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