Synthesis, thermal properties and photoisomerization of trans-[Ru(NO)Py2Cl2(H2O)]H2PO4⋅H2O

Abstract

The reaction of trans-[Ru(NO)Py 2Cl 2(OH)] with concentrated o-phosphoric acid, after washing the mixture with diethyl ether, gave trans-[Ru(NO)Py 2Cl 2(H 2O)]H 2 PO 4 ⋅2H 3 PO 4 ⋅H 2O (I) in nearly quantitative yield. The structure of this compound was determined by X-ray diffraction analysis: space group P-1. Washing of I with ethanol afforded the dihydrophosphate salt trans-[Ru(NO)Py 2Cl 2(H 2O)]H 2 PO 4 ⋅H 2O (II) (yield 97%). The thermal decomposition of I and II in a helium atmosphere resulted in the formation of ruthenium phosphide RuP as a predominant component along with Ru 2P or RuP 2. Preliminary photoisomerization experiments for trans-[Ru(NO)Py 2Cl 2(OH)] and trans-[Ru(NO)Py 2Cl 2(H 2O)]H 2 PO 4 ⋅H 2O suggested the presence of metastable states. DSC experiments have been carried out for both compounds. The measured kinetic parameters for the metastable decay for trans-[Ru(NO)Py 2Cl 2(H 2O)]H 2 PO 4 ⋅H 2O were E a = 90.7 ± 2.4 kJ/mol, log 10(k 0/sec −1) = 18.9 ±0.6, and T d = 217 K. Synthesis of trans-[Ru(NO)Py2Cl2(H2O)]H2PO4·H2O and [Ru(NO)Py2Cl2(H2O)]H2PO4·2H3PO4·H2O starting from trans-[Ru(NO)Py2Cl2(OH)] in nearly quantitative yields is reported. Preliminary photoisomerization experiments for trans-[Ru(NO)Py2Cl2(OH)] and trans-[Ru(NO)Py2Cl2(H2O)]H2PO4·H2O complexes have been performed, and metastable states have been detected. Heating of phosphate salts of ruthenium pyridine complexes, as synthesized, afford a mixture of nanoscale ruthenium phosphides.