Structural Investigations of trans-Rh(PY₃)₂(CO)X (X = F, Cl, NCO; Y = H, Me, Ph) Using Density Functional Theory and X-ray Analysis

Abstract

A study of trans-Rh(PY 3 ) 2 (CO)X (X ) F, Cl; Y ) H, Me) and trans-Rh(PH 3 ) 2 (CO)NCO using density functional theory is presented together with the results of new high-resolution, low-temperature x-ray data analysis of trans-Rh(PPh 3 ) 2 (CO)X (X ) F, NCO). In our calculations, we employed the Becke-exchange functional with the Lee, Yang, and Parr correlation functional (B-LYP) and the double-plus polarization basis set (DZP). Our optimized complexes have a slightly distorted square-planar structure with moderate bending of the phosphine ligands toward the uninegative ligand X -. The predicted structures compare favorably with experimental data for trans-Rh(PPh 3 ) 2 (CO)X (X ) F, Cl, NCO). New X-ray data for trans-Rh(PPh 3 ) 2 -(CO)X (X ) F, NCO) clearly indicate a nonlinear configuration of P-Rh-P atoms, in agreement with our calculations. The apparent linear configuration of P-Rh-P atoms recently reported for the structure of the orthorhombic form of trans-Rh(PPh 3 ) 2 (CO)Cl is most likely an artifact resulting from the disorder and symmetry imposed by the space group of the crystal structure. Computationally predicted vibrational frequencies ν(C-O) and ν(C-N) (for X ) NCO) compare well with solution-phase FTIR data.

Diminished electron density in the Vaska-type rhodium(I) complextrans-[Rh(NCBH3)(CO)(PPh3)2]

“…This can result from less effective orbital overlap between the Rh I atom and the CO ligand due to competition between CO and BH 3 CN À for -backbonding with the Rh I atom. The relationship between the Rh-C and C-O bond lengths was demonstrated previously based on computational and experimental results, namely that the shorter the Rh-C bond length, the longer the C-O bond length (Wierzbicki et al, 1996). Experimental results (Table 3) indicate that this relationship is also observed in the trans-[RhX(CO)(PPh 3 ) 2 ] (X = F, Cl, I, NCO or BH 3 CN) complexes.…”

A crystallographic and DFT study on Vaska-type trans-[Rh(CO)Cl(PR3)2] complexes containing flexible ligands: The molecular structure of trans-[Rh(CO)Cl{P(OC6H5)3}2]

“…The bond distances and angles from crystal structures were in agreement with the values predicted theoretically [36]. Similarly, theoretical calculations on trans-[Rh(CO)Cl(PPh 3 ) 2 ] predicted small energy differences between the staggered and eclipsed conformations, with the eclipsed conformation more stable [37].…”

“…Data obtained from the various geometrical optimizations are summarized in Table 5 as well as the appropriate geometrical parameters from the crystallographic data. For comparison the data on previously calculated structures of trans-[Rh(CO)Cl(PY 3 ) 2 ] (Y = H, Me) [37] are also included in Table 5.…”

Synthesis and reactivity of rhodium fluoro complexes

“…The rhodium fluoro complexes 2, 5 and 6 have been described before and have been identified by their NMR spectroscopic and crystallographic data [21,27,29]. However, in the case of [RhF(PEt 3 ) 3 ] (5), spectra with a better resolution have been obtained (Fig.…”