625079-84-7Relevant articles and documents
Carbon monoxide coordination and reversible photodissociation in copper(I) pyridylalkylamine compounds
Fry, H. Christopher,Lucas, Heather R.,Sarjeant, Amy A. Narducci,Karlin, Kenneth D.,Meyer, Gerald J.
, p. 241 - 256 (2008/10/09)
Systematic studies of CO coordination and photodissociation have been carried out for a series of copper(I) carbonyl compounds possessing tripodal tetradentate ligands, [CuI(L)(CO)]B(C6F5) 4 (L = Me2N-TMPA (1Me2N), MeO-TMPA (1 MeO), H-TMPA (1H), PMEA (2pmea), PMAP (2 pmap), BQPA (3bqpa). Detailed structural, electrochemical, and infrared characterization has been accomplished. In addition, various experimental techniques were utilized to determine equilibrium binding constants (KCO), association (kCO), and dissociation (k -CO) rate constants, as well as the thermodynamic (ΔH ○, ΔS○) and activation parameters (ΔH?, ΔS?) that regulate these processes. With increased ligand-electron-donating ability, greater π back-bonding results in stronger Cu-CO bonds, leading to KCO values on the order 1 Me2N-CO > 1MeO-CO > 1H-CO. With systematic synthetic expansion of the five-membered chelate rings like 1 R to six-membered chelate rings like 2R, the stability of the CO adduct decreases, 1H-CO > 2pmea-CO > 2 pmap-CO. The CO-binding properties of 3bqpa did not follow trends observed for the other compounds, presumably because of its bulkier ligand framework. Through solid- and solution-state analyses, we concluded that the photolabile carbonyl species in solution possess a tridentate coordination mode, forming strictly five-membered chelate rings to the copper ion with one dangling arm of the tripodal ligand. Carbon monoxide reversibly photodissociated from complexes 1Me2N-CO, 1HeO-CO, 1H-CO, and 3bqpa-CO in coordinating (CH3CN) and weakly coordinating (THF) solvent but not from 2pmea-CO and 2pmap-CO. Comparisons to O2-binding data available for these copper complexes as well as to small molecule (O2, CO, NO) reactions with hemes and copper proteins are discussed.
The rate of O2 and CO binding to a copper complex, determined by a flash-and-trap technique, exceeds that for hemes.
Fry, H Christopher,Scaltrito, Donald V,Karlin, Kenneth D,Meyer, Gerald J
, p. 11866 - 11871 (2007/10/03)
The observation and fast time-scale kinetic determination of a primary dioxygen-copper interaction have been studied. The ability to photorelease carbon monoxide from [Cu(I)(tmpa)(CO)](+) in mixtures of CO and O(2) in tetrahydrofuran (THF) between 188 and 218 K results in the observable formation of a copper-superoxide species, [Cu(II)(tmpa)(O(2)(-))](+) lambda(max) = 425 nm. Via this flash-and-trap technique, temperature-dependent kinetic studies on the forward reaction between dioxygen and [Cu(I)(tmpa)(thf)](+) afford activation parameters DeltaH = 7.62 kJ/mol and DeltaS = -45.1 J/mol K. The corresponding reverse reaction proceeds with DeltaH = 58.0 kJ/mol and DeltaS = 105 J/mol K. Overall thermodynamic parameters are DeltaH degrees = -48.5 kJ/mol and DeltaS degrees = -140 J/mol K. The temperature-dependent data allowed us to determine the room-temperature second-order rate constant, k(O2) = 1.3 x 10(9) M(-1) s(-1). Comparisons to copper and heme proteins and synthetic complexes are discussed.
