Ab initio calculations on the bonding properties of isonitrile and nitrile ligands

Abstract

Ab initio calculations have been performed on CNCH3 and NCCH3 to evaluate the change in a-donor and x-acceptor character as a function of molecular geometry. For CNCH3, it is shown that as the CNCHB angle decreases, the x-acceptor character increases markedly, while the x-donor character remains essentially constant. For NCCH3, calculations indicate a potential x-donor character for the ligand; a similar decrease in the NCCH3 angle results in a decrease in n-acceptor capability. The results are discussed in the light of relevant structural, spectroscopic, and kinetic literature data. * Calculations were carried out using the program HONDO (M.

Theoretical studies of transition metal complexes with nitriles and isocyanides

“…Analysis of the linear and angular structures of the nitrile ligand NCMe (Fig. 12 b) demonstrated that acetonitrile exhibits very weak p-acceptor properties due to a small degree of localisation of the p*-MO on the terminal N atom although the energy of the p*-MO of the nitrile ligand determined in the study 48 is comparable with the energy of the p*-MO of the isocyanide ligand. The bent distortion of the NCMe ligand must lead to weakening of its acceptor properties due to the total destabilisation of the p*-MO.…”

“…Hence, the DCD model must be applied to the description of the properties of the nitrile complexes with caution. Finally, analysis of the compositions of the frontier MOs of acetonitrile and methyl isocyanide 48 demonstrated that nitriles are weaker s-donors than isocyanides due to substantially lower energy of the valence occupied s-orbitals of NCR compared to those of CNR.…”

“…The correlation diagrams of the MOs for linear and angular methyl isocyanide 48 show that the bent distortion of the ligand leads to an increase in the energy of the p-MO and this orbital becomes the highest occupied MO, whereas the energy of the p*-MOs decreases (Fig. 12 a).…”

Reactivity of Silyl-Substituted Heterobimetallic Iron–Platinum Hydride Complexes towards Unsaturated Molecules, I Alkyne Insertions into the Platinum-Hydride Bond, Phosphane-Induced σ-Alkenyl–μ-Vinylidene Rearrangements and Formation of μ-Isonitrile Complexes

“…Suitable crystals were obtained by layering a saturated dichloromethane π-acceptor capacity of bridging isonitrile ligands is correlated to the degree of inclination. [19] Because the isonitrile solution with Et 2 O. The iron and platinum centers are linked by a dppm bridge and a metalϪmetal bond, whose complexes 6 represent electron-rich systems due to the presence of two metal centers in low oxidation states with three FeϪPt separation of 2.552(4) Å is almost identical to that of the vinylidene complex [(OC) 3 Fe{µ-CϭC(H)Ph}(µ-phosphorus donors as ligands, a strongly bent isonitrile bridge behaving as a good π-acceptor can at least partially dppm)Pt(PPh 3 )] [2.5503(8) Å ].…”

“…[19] The C(1)ϪNϪC (2) angle is phane ligand on platinum, which would otherwise interfere unfavorably with the 2,6-xylyl group. extremely bent [122.1(8)°], the xylyl group being oriented towards the Fe(CO) 3 moiety.…”