STRUKTURDYNAMISCHE ORGANOMETALL-KOMPLEXE. III. SYNTHESE, STRUKTUR UND BINDUNGSVERHAELTNISSE DER KOMPLEXE (η5-C5H5)Pd(η1-C5H5)PR3

Article abstract of DOI:10.1016/0022-328X(83)85075-X

The complexes (η⁵-C5H5)Pd(η¹-C5H5)PR3 which are prepared from 2(μ-OCOCH3)2 and TlC5H5 are fluxional in solution.According to the 1H and 13C NMR spectra at various temperatures, two dynamic processes occur.The process with the higher activation energy is a ?/? (η⁵/η¹) exchange of the two different cyclopentadienyl ligands, whereas the second one with the lower activation energy presumably is a metallotropic rearrangement (1,2-shift).The coalescence temperature for the η⁵/η¹ exchange depends on the size of the phosphine.The X-ray structural analysis of (C5H5)2PdPPr3ⁱ proves that it exists as a frozen η⁵+η¹ structure in the crystal with the palladium approximately in a square-planar coordination.The η⁵-bonded cyclopentadienyl ring shows some unusual bonding patterns which are obviously electronic in nature.EHT-MO calculations for (η⁵-C5H5)PdCH3(PH3) indicate that in tghis model system alternating C-C distances in the ring and a stronger bond of the metal to one of the five carbon atoms of the C5H5 ligand are to be expected.The calculations suggest that in similar complexes possessing a six-electron donor ligand like C5H5^- and a metal fragment which is isolobal to PdCH3(PH3)⁺, analogous distortions should be observed.Some reactions of the compounds (η⁵-C5H5)Pd(η¹-C5H5)PR3 are described.