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

The reaction of trans -[Ru(NO)Py 2 Cl 2 (OH)] with concentrated o-phosphoric acid, after washing the mixture with diethyl ether, gave trans- [Ru(NO)Py 2 Cl 2 (H 2 O)]H 2 PO 4 ⋅2H 3 PO 4 ⋅ H 2 O ( 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 2 Cl 2 (H 2 O)]H 2 PO 4 ⋅ H 2 O ( 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 2 P or RuP 2 . Preliminary photoisomerization experiments for trans- [Ru(NO)Py 2 Cl 2 (OH)] and trans- [Ru(NO)Py 2 Cl 2 (H 2 O)]H 2 PO 4 ⋅ H 2 O 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 2 Cl 2 (H 2 O)]H 2 PO 4 ⋅ H 2 O were E a = 90.7 ± 2.4 kJ/mol, log 10 ( k 0 /sec −1 ) = 18.9 ±0.6, and T d = 217 K. Graphical Abstract Synthesis of trans -[Ru(NO)Py 2 Cl 2 (H 2 O)]H 2 PO 4 ·H 2 O and [Ru(NO)Py 2 Cl 2 (H 2 O)]H 2 PO 4 ·2H 3 PO 4 ·H 2 O starting from trans -[Ru(NO)Py 2 Cl 2 (OH)] in nearly quantitative yields is reported. Preliminary photoisomerization experiments for trans -[Ru(NO)Py 2 Cl 2 (OH)] and trans -[Ru(NO)Py 2 Cl 2 (H 2 O)]H 2 PO 4 ·H 2 O 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.