In search for a hydride‐carbene bond

Abstract

By presenting a large group of dimers featuring hydride-carbene bond between silane and various carbenes, we show that electrophilic properties of singlet carbenes can manifest also to a hydridic, ie, negatively charged, hydrogen atom of a hydride. This type of interaction is traced by the corresponding bond path in 18 cases. However, taking into account the fact that in the case of large interatomic distances, the electrostatic potential maps are better indicators of dominant intermolecular interactions, it is shown that the amount of dimers with the hydride-carbene bond is even larger, as indicated by both the proximity and correct orientation of the -hole on the carbene carbon atom and the negative surface of the hydridic hydrogen of the silane molecule. The hydride-carbene bond is weak, especially when compared with the hydride-triel bond also involving the silane. In contrast to the latter, the intermolecular charge transfer is negligible. Moreover, the local electrostatic interaction involving the carbene carbon's -hole is not necessarily predominant in stabilization of all the carbene· · ·silane complexes.

Physical nature of silane⋯carbene dimers revealed by state‐of‐the‐art ab initio calculations

“…Bending of the C⋯HSi contact allows interaction between the negative electrostatic potential ring located around the SiH bond of the silane and the positive π ‐hole on the carbene carbon. However, as already mentioned in the introduction, it has been shown that the local electrostatic interaction involving this π ‐hole is not necessarily predominant in stabilization of carbene⋯silane complexes. Also, fairly long intermolecular distances (ca.…”

“…Nonlinearity of the C⋯HSi contact has been previously explained by reference to the electrostatic potential maps. One of these maps is shown in Figure for an example SiH 4 ⋯CCl 2 dimer.…”

“…Calculations were performed for four fully optimized ( ω B97X‐D/6‐311++G(2df,2pd)) silane⋯carbene dimers, where carbenes are CHCl, CCl 2 , CMeCN (MeCH 3 ), and cyclopropanylidene. In order to increase the accuracy of the optimization procedure and numerical integration, cutoffs on forces and step size that are used to determine convergence were additionally tightened (0.000015 and 0.000010 for maximum force and its root mean square, respectively, and 0.000060 and 0.000040 for maximum displacement and its root mean square, respectively), and integration grid was increased to the (99, 590) one (UltraFine in Gaussian 09) having 99 radial shells and 590 angular points per shell.…”

“…As mentioned in Introduction, some previous results suggested that interactions between silane and carbenes may be mainly of dispersive nature, which is why a very accurate description of the dispersion term is particularly important. Computation of this contribution using t 2 amplitudes from the CCD method leads to the next variants of the SAPT method: SAPT2 + (3)(CCD) δ MP2 and SAPT2 + 3(CCD) δ MP2—the most accurate methods currently used to decompose the interaction energy .…”

“…J.) has for the first time presented theoretical proof of existence of a hydride‐carbene bond, that is, an interaction between a hydridic, that is, partially negatively charged, hydrogen atom, and a singlet carbene . Thus, it has been shown that electrophilic properties of singlet carbenes can manifest not only to nitrogen and phosphorus atoms but also to a hydridic hydrogen of a hydride molecule.…”