title: A fractional bond order of 1/2 in Pd(2)(5+)--formamidinate species; the value of very high-field EPR spectra.
abstract: Reaction of Pd(2)(DAniF)(4), 1, (DAniF = di-p-anisylformamidinate) with 1 equiv of AgPF(6) in CH(2)Cl(2) at or below -10 degrees C produces the paramagnetic species [Pd(2)(DAniF)4]PF(6), 1-PF(6), that has been studied by X-ray crystallography, UV-vis spectroscopy, electrochemistry, and multifrequency (9.5, 34.5, 110, and 220 GHz) EPR spectroscopy. Upon oxidation of the precursor, the Pd-Pd distance decreases by 0.052 Angstrom from 2.6486(8) to 2.597(1) Angstrom. The EPR spectra show broad signals with line widths of about 1000 G. The spectra collected at high field show a large spread of g tensor components ( approximately 0.03), but these are masked at lower frequencies (9.5 and 34.5 GHz). A reinvestigation using high-field EPR of the p-tolyl analogue, which is the only other structurally characterized Pd(2)(5+) species (Cotton, F. A.; Matusz, M.; Poli, R.; Feng, X. J. Am. Chem. Soc. 1988, 110, 1144), shows that this species, which had been reported to give an isotropic 9.5 GHz EPR spectrum, also gives anisotropic 110 and 220 GHz EPR spectra with a similarly large spread of g tensor components consistent with the unpaired electron residing in a metal-based MO. The results of these studies and calculations using density functional theory are consistent with the oxidation being metal-based, resulting in an uncommon Pd(2)(5+) species with a Pd-Pd bond order of 1/2.
authors.affiliation: Department of Chemistry and Laboratory of Molecular Structure and Bonding, P.O. Box 30012, Texas A and M University, College Station, Texas 77842-3012, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Berry
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.forename: Eberhard
authors.initials: E
authors.lastname: Bothe
authors.forename: F Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Naresh S
authors.initials: NS
authors.lastname: Dalal
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Ibragimov
authors.forename: Narpinder
authors.initials: N
authors.lastname: Kaur
authors.forename: Chun Y
authors.initials: CY
authors.lastname: Liu
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Murillo
authors.forename: Saritha
authors.initials: S
authors.lastname: Nellutla
authors.forename: J Micah
authors.initials: JM
authors.lastname: North
authors.forename: Dino
authors.initials: D
authors.lastname: Villagran
mesh_terms: D016880:Anisotropy; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D005559:Formamides / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014050:Toluene / Q000031:analogs & derivatives
chemical_list: D005559:Formamides; D009942:Organometallic Compounds; D014050:Toluene; D010165:Palladium