Redox chemistry of a pair of complexes that contain the bridging bis(diphenylphosphino)methane ligand and the Re26+ and Re24+ cores: Re2(.mu.-Cl)2(.mu.-dppm)2Cl4 and [Re2(.mu.-dppm)2Cl3(NCR)2]PF6 (R = CH3, C2H5, C6H5)
Academic Article
Overview
Identity
Additional Document Info
Other
View All
Overview
abstract
The oxidant NOPF6 has been used to prepare the new paramagnetic dirhenium complexes [Re2(-dppm)2Cl3(NCR)2](PF6)2 (dppm = bis(diphenylphosphino)methane; R = CH3, C2H5, C6H5) from the monocationic precursors. The compounds are derivatives of the Re25+ core. The doubly bonded dirhenium(III) complex Re2Cl6(dppm)2 undergoes a one-electron oxidation with NOX (X = BF4-, PF6-), and a one-electron reduction with cobaltocene, to yield paramagnetic ions with bond orders of 1.5. The resulting monocation and monoanion provide examples of previously unknown types of metal-metal bonds of order 1.5 (2221 and 22221, respectively). The structural identity of the monocation, a rare example of a Re27+ core complex, has been established through an X-ray crystal structure determination on the salt [Re2(-C1)2(-dppm)2Cl4]H2PO4-H3PO4-4H2O. This compound crystallizes in the monoclinic space group C2/c with cell dimensions a = 23.524 (4) , b = 13.354 (3) , c = 19.717 (5) , = 93.60 (2), and Z = 4. The cation possesses crystallographic inversion symmetry. The phosphate groups (also related by inversion symmetry) and the waters are disordered. From 5418 unique data collected with use of Mo K radiation on an Enraf-Nonius CAD-4 diffractometer (2 < 50; -2 scans), 3967 data were considered observed (I > 2(I)). The data were refined by block-diagonal least-squares minimizing w(|Fo|-|Fc|)2 with w = 1/2(F) to an R of 0.051. The Re-Re distance in this complex (2.6823 (6) ) is appreciably longer than that in the parent neutral complex Re2(-Cl)2(-dppm)2Cl4 (2.616 (1) ). 1985, American Chemical Society. All rights reserved.
