A fractional bond order of 1/2 in Pd(2)(5+)--formamidinate species; the value of very high-field EPR spectra.
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.
Berry
John F
JF
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.
Bill
Eckhard
E
Bothe
Eberhard
E
Cotton
F Albert
FA
Dalal
Naresh S
NS
Ibragimov
Sergey A
SA
Kaur
Narpinder
N
Liu
Chun Y
CY
Murillo
Carlos A
CA
Nellutla
Saritha
S
North
J Micah
JM
Villagran
Dino
D
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
D005559:Formamides; D009942:Organometallic Compounds; D014050:Toluene; D010165:Palladium