Synthesis and characterization of ruthenium(II) complexes incorporating 4′-phenyl-terpyridine and triphenylphosphine

Abstract

The syntheses of two new series of ruthenium(II) complexes incorporating substituted 4′-phenylterpyridine, triphenylphosphine and chloride (A Series) or hydride (B Series) are reported. In both series 4′-phenyl-terpyridine incorporated substituents of varying electronic character at the 4-position: 4`-(4-chlorophenyl)-2,2´:6´,2``-terpyridine (ClPh-tpy); 4`-(4-nitrophenyl)-2,2´:6´,2``-terpyridine (NO 2 Ph-tpy) and 4`-(4-methoxyphenyl)-2,2´:6´,2``-terpyridine (OMePh-tpy). The complexes have been characterized by elemental analysis and UV-Vis, IR and NMR spectroscopy and their electrochemical properties studied. The substituents on the 4′-phenylterpyridine ligand influence the properties of the metal center. For all complexes prepared, λ max of a characteristic low energy band in the UV-Vis spectrum was found to move to shorter wavelengths as the solvent polarity increased (a hypsochromic shift). For the B series complexes, the low energy band was broader and undergoes a small shift to lower frequencies as a result of the substitution of chloride by a hydride. The 1 H-and 31 P-NMR spectra clearly indicate that the geometry of the 4′-phenyl-terpyridine ligand is meridional in the complexes, with the two triphenylphosphines trans to each other. Upon optimization of the experimental procedures the yields increased to 70% for the B series complexes.

Blocking Metal Nanocluster Growth through Ligand Coordination and Subsequent Polymerization: The Case of Ruthenium Nanoclusters as Robust Hydrogen Evolution Electrocatalysts

“…[ 30 ] These two characteristic bands were blue shifted to 286 and 331 nm in Ru 3+ ─TPY─NH 2 owing to the bonding of TPY─NH 2 with Ru 3+ through three near‐coplanar N. [ 31 ] Interestingly, upon TPY‐NH 2 coordination with Ru 3+ , a new broad band at 512 nm was detected, which could be assigned to metal‐ligand charge‐transfer ( MLCT , Ru 3+ ─TPY─NH 2 ) transitions (Figure S5a, Supporting Information). [ 32 ] As shown in Figure S5b (Supporting Information), compared with the TPY─NH 2 fluorescence spectrum, the spectrum of Ru 3+ ─TPY─NH 2 displayed a distinct blue shift from 531 to 502 nm, which is associated with the coordination of TPY─NH 2 with Ru 3+ ions. [ 33 ]…”