title: Resonance Raman, X-ray Crystallographic, and Magnetic Susceptibility Studies of Metal-Metal-Bonded MoRu and WOs Porphyrin Dimers. 1. Evidence for an Unusual MO Diagram.
abstract: Solution (VT NMR, Evans method magnetic susceptibility, resonance Raman) and solid-state (SQUID magnetic susceptibility, X-ray crystallography) spectroscopic studies of intertriad heterodimeric [(OEP)MoRu(OEP)] (1), [(OEP)WOs(OEP)] (2), and [(OEP)MoRu(TPP)]PF(6) (3(+)) metalloporphyrins are reported (OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato; TPP = 5,10,15,20-tetraphenylporphyrinato). Solution and solid-state magnetic susceptibility data indicate that 1 and 2 contain two unpaired electrons in the ground electronic configuration. The presence of a delta bond in 3(+) has been confirmed by structural characterization. The experimental evidence is consistent with a molecular orbital ordering, sigma < pi < delta < pi < delta, which is different from that seen for homologous metalloporphyrin dimers with homometallic or intratriad heterometallic multiple metal-metal bonds. Resonance Raman data suggest that the heterometallic bonds are slightly stronger than isoelectronic homometallic species.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Département de Recherche Fondamentale sur la Matière Condensée/SCIB, CEA-Grenoble, 38054 Grenoble, France.
authors.forename: James P.
authors.initials: JP
authors.lastname: Collman
authors.forename: S. T.
authors.initials: ST
authors.lastname: Harford
authors.forename: Stefan
authors.initials: S
authors.lastname: Franzen
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Marchon
authors.forename: Pascale
authors.initials: P
authors.lastname: Maldivi
authors.forename: Andrew P.
authors.initials: AP
authors.lastname: Shreve
authors.forename: William H.
authors.initials: WH
authors.lastname: Woodruff