Mononuclear rhenium carbonyls on magnesia: characterization of the metal-support interface by extended x-ray absorption fine structure spectroscopy

Structure and Reactivity of a Mononuclear Gold‐Complex Catalyst Supported on Magnesium Oxide

“…Extended X‐ray absorption fine structure (EXAFS) results characterizing 1 (measured at the Au L III edge, 11 919 eV, Table 2), show that in the surface complex the gold center was also bonded to two oxygen atoms. These are inferred to be part of the MgO surface (although the exact bonding sites are unknown), because the AuO separation was found to be 2.16 Å (vs. 2.08 Å in 2 21), typical of MO bonding distances in other zeolite‐ and oxide‐supported mononuclear metal complexes (e.g., [Rh(CO) 2 {OAl}{OSi}] (supported on highly dealuminated zeolite Y), 2.15 Å;3b [Ru(CO) 2 {OAl} 2 ] (on γ‐Al 2 O 3 ), 2.17 Å;22 and [Re(CO) 3 {OMg}{HOMg} 2 ] (on MgO), 2.13 Å3a, 23). Another Au–O contribution in the EXAFS spectrum of 1 was found at a nonbonding distance of 2.85 Å (with a coordination number of 0.9), along with another (weak) contribution tentatively identified as Au–Mg ( N =0.9, 2.72 Å).…”

Synthesis and characterization of catalytic iridium nanoparticles in imidazolium ionic liquids

“…Note that this bond distance is slightly shorter than those observed by EXAFS for Ir-O bonds in iridium particles deposited on metal oxides [52]. This relatively short metal-oxygen distance may be explained by the interaction of metal atoms with small positive charges with oxygens of the interface [53,54].…”

Prototype Supported Metal Cluster Catalysts: Ir4 and Ir6

“…[13,19] The data consistently indicate IrÀO support distances of approximately 98 www.chemcatchem.org 2.1 , matching typical IrÀO bonding distances. [36,37] Such results are the norm for Group 8 metal carbonyl complexes on oxides [13,14,23,[26][27][28][32][33][34] and zeolites; [9,[10][11][12]19] the nearness of the Ir atom to the support implies a significant distortion of the position of the CO ligands from those in isolated iridium carbonyl clusters.…”