Metal–carbon vibrational modes as a probe of the trans influence in vinylidene and carbonyl rhodium(I) complexes

Mechanistic aspects regarding the formation of metal vinylidenes from alkynes and related reactions

“…According to DFT calculations of trans-[RhF(PMe 3 ) 2 (‚C‚CH 2 )], LUMO in this complex is pz of Ca, as expected, with small anti-bonding contribution from a Rh dp-orbital, whereas the HOMO is mainly composed of dz 2 orbital of Rh [16]. Examination of the m(Rh‚C) band at around 570 cm À1 in FT-Raman spectroscopy of a series of similar complexes has shown that the vinylidene group is a better r-donor and less effective p-acceptor as compared to CO ligand.…”

Selective Cleavage by Acids of One Metal–Carbon σ‐Bond of a Bis(ortho‐platinated) Triarylphosphane: A 31P NMR trans‐Influence Series Based on the Unit Pt(κ2‐C6H3‐5‐Me‐2‐PPh2)(PPh2‐4‐tol)

“…[35] In contrast, the order F -Ͻ Cl -Ͻ Br -Ͻ I -is derived from ν(Rh=C) values in planar rhodium(I) complexes [RhXL(PiPr 3 ) 2 ] (L = C=CH 2 , CO). [84] This represents an example of the well-known dependence of the placement of a ligand in the trans-influence series on the physical method used to assess it. [5] Exceptionally, for the three heavier halides, there is a perfect linear correlation between J(Pt-P B ) and δ(P B ), but fluoride is anomalous.…”

Routes to unique palladium A-frame complexes with a bridging fluoro-ligand

“…This model has been questioned by several research groups, who suggest that fluorine is a very poor p-donor, but the properties of the transition-metal fluorine bond can be explained by its ionic component. 4,11,13 At square-planar d 8 complexes electrostatic interactions lead to a raise in energy of the metal based orbitals. 13 In either case a stabilisation can be achieved by a push/pull interaction induced by a p-acceptor ligand in the trans-position to the fluoride.…”