Journal of Physical Chemistry A, Vol.119, No.24, 6326-6332, 2015
Probing the Hydrogen-Bonded Water Network at the Active Site of a Water Oxidation Catalyst: [Ru(bpy)(tpy)(H2O)](2+)center dot(H2O)(0-4)
The infrared- spectra Of gas-phase mass-selected [Ru(bpy)(tpy)(H2O)(2+)(H2O)(0-4) clusters (bPY = 2'2-bipyridine; tpy = 2,2':6,2 ''-terpyridine) in the OH stretching region are reported. These spedieS are formed by 'bringing the homogeneous X water oxidation catalyst [Ru(bpy)(tpy)(H2O](2+) from solution into the gas phase; via electrospray iOnitation (ESI) and reconstructing the water network at the active site by condenging additional water onto., the complex in a cryogenic ion trap. Infrared predissociation spectroscopy is used to probe the structure of these duSters, Via their distinctive OH,stretch frequencies, which are sensitive to the shape and strength of the local hydrogen-bonding network. The analysis of the Spectra, aided by electronic Structure calculations, highlights the formation of strong hydrogen bonds between the aqua ligarid and the solvating water fliolecules in the first solvation shell. These interactions are found to propagate through the subsequent solvation shells and lead to the stabilization of asymmetric solVation motifs. Electronic structure calculations show that these strong, hydrogen bonds- are promoted by Charge transfer from the H atom of the aqua ligand to The Ru-OH2 bond.