Thermoanalytical study of linkage isomerism in coordination compounds. Part III: A DSC study on the effect of counterion on the solid state isomerization of nitro and nitrito linkage isomers of pentaamminecobalt(III) complexes

Thermoanalytical Study of Linkage Isomerism in Coordination Compounds. Part 7. A DSC and DFT Investigation of Solid‐state Linkage Isomerization in Bis(thiocyanato)‐bipyridineplatinum(II) Complex

“…Generally, calculation of the kinetic parameters of the chemical transformations in inhomogeneous solid state is more complicated than that in homogeneous medium . To the best of our knowledge, there is few published work about the kinetic of the thiocyanate linkage isomerization in solution,, and there is no investigation on the kinetic measurements of this interconversion in solid state.…”

A Differential Scanning Calorimetry and Theoretical Study on the Isomerization of trans‐[Co(cyclam)(ONO)2]X (X = PF6–, ClO4–)

“…However, the thermal stability of these linkage isomers is different from those of recently studied related complexes. Our pervious study showed that both chemically prepared pure nitrito and nitro linkage isomers of trans ‐bis(ethylenediamine)cobalt(III) hexafluorophosphate20 and pentaaminecobalt(III) complexes18,19 are metastable states at ambient temperatures and reach an stable equilibrium state at elevated temperatures. In these instances, the stable state is a mixture of the nitro and nitrito isomers as major and minor components, respectively.…”

“…Our previous DSC studies19 showed that the kinetic and thermodynamic parameters of the isomerization depend on the nature of the complex counterions. Also, recent DSC studies on the solid‐state thermal interconversion of Co III nitropentaamine and nitritopentaamine complexes18,19 as well as trans ‐bis(ethylenediamine)20 complexes revealed that the pure nitrito and nitro isomers are both metastable states, which convert to an equilibrium state upon heating. Both nitro and nitrito isomers are present in the stable equilibrium state as major and minor components, respectively.…”

“…The first observation of the photoinduced linkage isomerism of NO 2 ‐containing transition metal complexes was reported in 1955 by Adell, who found that sunlight irradiation of the yellow crystals of [Co(NH 3 ) 5 (NO 2 )]XY complexes resulted in the corresponding red nitrito isomers of [Co(NH 3 ) 5 ONO]XY 12. To date, thermal nitrito–nitro isomerization has been observed in several complexes, including [Co(MeNH 2 ) 5 ONO] 2+ , cis ‐ and trans ‐[Co(MeNH 2 )(NH 3 ) 4 ONO] 2+ , trans ‐[Co(MeNH 2 )(en) 2 ONO] (en = ethylenediamine), cis ‐ and trans ‐[CoL 14 (ONO)] 2+ (L 14 = 6‐methyl‐1,4,8,11‐tetraazacyclotetradecane‐6‐amine),13 cis ‐ and trans ‐[Co(en) 2 (ONO) 2 ] + ,14 cis ‐[Co(en) 2 (ONO)(NO 2 )] + ,15 trans ‐[Co(cyclam)(NH 3 )(ONO)] 2+ (cyclam = 1,4,8,11‐tetraazacyclotetradecane), trans ‐[Co(en)(dien)ONO] 2+ (dien = diethylenetriamine), [Co(en) 2 (NH 3 )ONO] 2+ ,16 cis ‐[Co(NH 3 ) 4 (ONO) 2 ] + and cis ‐[Co(NH 3 ) 4 (ONO)H 2 O] 2+[17] in solution, and also [Co(NH 3 ) 5 ONO]X 2 , [Co(NH 3 ) 5 NO 2 ]X 2 (X = Cl – , Br – , I – , PF 6 – ),18,19 trans ‐[Co(en) 2 (ONO) 2 ]PF 6 , trans ‐[Co(en) 2 (NO 2 ) 2 ]PF 6 ,20 trans ‐[Ni(en) 2 (NO 2 ) 2 ],11 and M(porphyrin)(NO x )21,22 in the solid state. In addition, the photoisomerization of trans ‐[Cr(cyclam) 2 (ONO) 2 ]BF 4 ,23 M(porphyrin)(NO x ),6,24–26 and [Ni(dppe)(η 1 ‐ONO)Cl] [dppe = 1,2‐bis(diphenylphosphanyl)ethane]27 have been studied in the solid state.…”

Synthesis, Characterization and Antibacterial Activity of Novel 1,3-Diethyl-1,3-bis(4-nitrophenyl)urea and Its Metal(II) Complexes

“…Linkage isomerism occurs when an ambidentate ligand (e.g., NO 2 , SCN, CNO, etc.) binds to the metal center [8,9,10]. Nitro-nitrito metal complexes can be regarded as good examples of linkage isomerism, which was first described by Jørgensen and further developed through the syntheses of [(NH 3 ) 5 CoNO 2 ]Cl 2 and [(NH 3 ) 5 CoONO]]Cl 2 complexes by Werner [11].…”