Theoretical Characterization of a Highly Electrophilic Carbene

Abstract

The experimental geometry obtained from single-crystal X-ray diffraction data for a metalladiphosphanyl carbene precursor is compared with the results of theoretical calculations made at the ab initio level by using Hartree–Fock (HF) and Density Functional Theory (DFT) methods over the carbene itself. Theoretical geometry optimizations for the singlet ground state of [ Mn(CO)4(PH2)2C: ]+ have been performed with several hybrid functionals and basis sets. Calculated geometries showed a perfect C 2v symmetry in the highest levels of calculation and were somewhat relaxed when compared with the experimental ones; for instance, with the largest basis set, the P–C–P angle found was 124.8°, whereas C–P bond distances were both 1.667 Å, compared to 103.5(3)° and 1.718(5) Å, respectively, from the experimental data. The absence of a ligand attached to the C : atom in the calculated structure, which is present in the form of iodine in the experimental complex, is probably responsible, to a certain extent, for the discrepancies. In addition to the structural computations, in order to theoretically quantify the highly electrophilic character expected for the carbene, electron affinities were calculated and found to be between 6.24 eV and 6.97 eV at different DFT levels of calculation, which confirmed the expectations. In this respect, a comparison with the analogous [Ru(CNH)4(PH2)2C:]2+ carbene is also made, showing the possibility of experimentally trapping the manganese carbene.

A new synthetic route for the preparation of [Os3(CO)10(μ-OH)(μ-H)] and its reaction with bis(diphenylphosphino)methane (dppm): syntheses and X-ray structures of two isomers of [Os3(CO)8(μ-OH)(μ-H)(μ-dppm)] and [Os3(CO)7(μ3-CO)(μ3-O)(μ-dppm)]

“…The former WBI is consistent with the existence of an Os-Os single bond while the latter WBI is best interpreted within a 4c,4e framework involving bond-pair donation to the osmium centers from the bridging hydroxyl and hydride groups. 39,40 Coordination of the dppm ligand in 1 leads to steric crowding about the triply bridged Os-Os vector, and this accounts for B1 as the thermodynamically favored isomer where such contacts are minimized. The assumption concerning the steric environment was corroborated by DFT calculations on several different isomeric forms based on 1.…”

On the Existence of an N-Metalated N-Heterocyclic Carbene: A Theoretical Study

“…The scale factor used for ZPE was 0.9804 . Absolute energies for each compound were rather different by using different calculation levels, as usual; however, relative energies between different compounds were basically constant, with differences no greater than 0.1 kcal mol −1 by exchanging either method or basis set. B3P86/6-311++G(3df,3pd) was the final model adopted for further discussion.…”

Reactions of diphosphine-stabilized Os3 clusters with triphenylantimony: syntheses and structures of new antimony-containing Os3 clusters via Sb–Ph bond cleavage

“…The larger (stronger) WBI for the Os–C(benzylidene) (0.56 versus 0.32) and the Os–H (0.45 versus 0.31) bonds are associated with the Os(1) atom. 36 …”