A LOSS OF INNOCENCE - CHARGE-TRANSFER INTERACTIONS WITH PH3PNPPH3-ACCEPTOR( AS ELECTRON)

Comparison of [Cat] [CpCr(CO)2PEt3] (Cat = Et4N+ and Ph3PNPPh3+ (PPN+) ) by NMR, visible/UV, and infrared spectroscopy in CH3CN and in THF sh ows that ion pairing for the PPN complex occurs in THF, and that such pairing involves a detectable amount of charge transfer from anion to cation. This causes a rise in the CO stretching frequencies, which can be compared to the values in the fully-oxidized species CpCr(CO)2(PEt 3).. The crystal structure of both compounds shows a decrease in angle C-Cr-C to be the most evident consequence of charge transfer.