The impact of counterion on the metastable state properties of nitrosyl ruthenium complexes

Abstract

In the present study four new complexes of the trans-[RuNO(NH3)4F]2+ cation with noble-metal anions [PtCl6]2-, [PdCl4]2- and [PtCl4]2-, and perchlorate anion ClO4- were synthesized and characterized by spectroscopic (IR, UV/vis),...

Nitrosyl linkage photoisomerization in heteroleptic fluoride ruthenium complexes derived from labile nitrate precursors

“…New bands of ν(NO) appear at 1778, 1801 and 1784 cm -1 for I, II and II respectively. The shift of the bands are about 130 cm -1 to lower energy from positions of the GS, which is common for ruthenium nitrosyl complexes 2,21,22 . Populations of the MS1 were calculated from a decrease of the area under ν(NO) band of the GS (% MS1 = 100 -(I(ν(NO) GS after )/I(ν(NO) GS before ))•100) and are shown in Table 3.…”

“…The specific temperature (T d , decay temperature) at which the rate of reverse transformation equals 10 -3 s -1 earlier was suggested as a convenient parameter to compare the stability of linkage isomers of different complexes 19 . Our previous investigations clearly demonstrate that complexes with trans-coordinate ON-Ru-F have the highest thermal stability of metastable isomers MS1 among all known nitrosyl complexes [20][21][22] . Cationic complexes trans-[RuNOL 4 F] 2+ (L = NH 3 , Py) with different counterions exhibit decay temperatures of the MS1 in the range 289 -307 K and the main reason of such stability is the high electronegativity of trans-to-NO ligand, which favors the stability of the MS1 isomer 2,20,23,24 .…”

“…But in order to obtain high populations other parameters are involved, including appropriate absorption properties in the three states GS, MS1 and MS2 allowing for efficient transfer GS→MS2→MS1, without corresponding backtransferring processes 48,49 . Also the counter ion can have a significant influence on the maximum achievable population, as has been shown by Cormary et al on a series of trans-[RuNO(py) 4 L] 2+ (L = Cl -, Br -) compounds 50 and on series of trans-[RuNO(NH 3 ) 4 F] 2+ complexes 21 . The intermolecular contacts of the NO ligands are shown in Table S2.…”

“…In order to compare the thermal stability of the MS1 with that found for other compounds, decay temperatures T d are calculated at k = 10 -3 s -1 using Arrhenius law and shown in Table 4 19 . All compounds show very high decay temperatures of MS1 (the highest decay temperature was found in the trans-[RuNO(NH 3 ) 4 F][PdCl 4 ], which equals 307 K 21 ). The high MS1 thermal stability is due to electronegative fluoride ligand in trans-position to NO, which greatly increases the activation energy of the reaction MS1→GS 20,23 .…”

“…Cationic complexes trans-[RuNOL 4 F] 2+ (L = NH 3 , Py) with different counterions exhibit decay temperatures of the MS1 in the range 289 -307 K and the main reason of such stability is the high electronegativity of trans-to-NO ligand, which favors the stability of the MS1 isomer 2,20,23,24 . By changing the counterion the thermal stability of the linkage isomers can be influenced, thereby reaching record high decay temperatures 21 . Therefore, in the framework of our investigations, we aim now to study the influence of changing equatorial ligands on the thermal stability of the linkage isomers MS1 and MS2.…”