Multidimensional Quantum Dynamical Study of β-Hydrogen Transfer in a Cationic Rhodium Complex

Abstract

The dynamics of migratory insertion and beta-hydrogen elimination in the cationic complex [CpRh(PH3)H(C2H4)]+ is studied from a quantal point of view. On the basis of DFT results for the relevant stationary points of the potential energy surface, three coordinates are identified that vary strongly during the reaction. A suitable three-dimensional grid, along with an appropriate kinetic energy operator, are constructed that are employed in the subsequent wave packet propagations. The latter are performed in the spirit of transition state spectroscopy and start from the various saddle points of the potential energy surface. Vibrational periods and lifetimes for these elementary processes, relevant to homogeneous catalysis, are obtained in this way for the first time. This work is considered to provide the basis for a subsequent treatment of equilibrium rate constants and to shed new light on the electronic factors governing these prototypical reaction steps.

Coordination of Ethylene to a Zwitterionic Rh(III) Half-Sandwich Complex: Influence of Ambiphilic Ligands on Reactivity

“…The geometry of π-complex 4 was optimized with the B3LYP hybrid functional and the combined SDD(Rh)/6-31 g**(C,H,Al,P) basis set and is shown in Figure , where most of the hydrogen atoms have been omitted for simplicity. The C−C bond distance for coordinated ethylene of the optimized complex is 1.397 Å, a value which falls between those obtained for the CpRhH(C 2 H 4 )PH 3 (1.408 Å and 1.391 Å) and CpRhMe(C 2 H 4 )PH 3 (1.391 Å) model complexes.…”

Influence of Ligands on the Dynamics of Hydrogen Elimination in Cationic Complexes of Co and Rh

“…This enabled us to determine time constants for the motion along the reaction path, as well as lifetimes arising from hydrogen elimination, for two cationic Co and Rh complexes for the first time . While this initial study was based on the quantum dynamics on a one-dimensional reaction path following a Franck−Condon (FC) type excitation, this treatment has subsequently been extended to two and three nuclear degrees of freedom, and their interplay with the motion along the reaction coordinate has been established …”

Exact and constrained kinetic energy operators for polyatomic molecules: The polyspherical approach

“…In Ref. [198], this strategy was adopted to calculate the KEO in order to undertake a first quantum dynamical study of migratory insertion and hydrogen elimination in a representative metal complex [CpRh(P H 3 )H(C 2 H 4 )] + . As for ethene, it was first necessary to identify a set of relevant coordinates.…”

“…If we keep only six internal polyspherical coordinates, as suggested in Ref. [198], R H , θ, ϕ, R (the length of −−−−→ GG RhH ), R CC (the distance between the two C atoms in C 2 H 2 ), and γ (the third Euler angle of the subsystem C 2 H 2 that is depicted in Figure ), the 'main' term of the final KEO for total J = 0 reads…”

“…In Ref. [198], the 'correction' and the extra-potential term were neglected. The successive separation into subsystems and the use of Jacobi vectors joining the different subsystems ( R 1 2 , R) allows the active coordinates to strongly decouple the active coordinates from the rest of the system in the KEO.…”