# Bis‐Dichlorosilyl Functionalized C4‐Cumulene With Unique Bonding Scenario

## TL;DR

This paper describes a new compound with unique silicon-carbon bonding and explains its structure and bonding using advanced computational methods.

## Contribution

The paper reveals unprecedented chemical bonding in a silylene-functionalized C4-cumulene using EDA-NOCV analysis.

## Key findings

- Compound 2 has electron-sharing and dative covalent sigma bonds between the Ph2C4 fragment and silyl-amidine groups.
- The bonding is due to the electron-deficient olefin and electron-rich N-donating groups on silicon atoms.
- Compound 2 shows unique bonding compared to previously reported compound 3.

## Abstract

This work reports the preparation and computational investigation of a bis‐dichlorosilyl functionalized C4‐cumulene (2), which was synthesized by employing Amidinato‐chlorosilylene, L(Cl)Si: (L = PhC(N
t
Bu)2). Compound 2 was characterized by single‐crystal X‐ray diffraction, mass spectrometry, and NMR spectroscopy. The stability, distribution of spin densities, and the nature of Si‐C bonds of 2 were studied by employing natural bond orbital (NBO) analysis, atoms in molecules (AIM), and energy decomposition analysis‐natural orbital for chemical valence (EDA‐NOCV). The EDA‐NOCV analysis showed that compound 2 possesses electron‐sharing covalent sigma and dative covalent sigma bonds (Si↔C and C→Si) between the Ph2C4 fragment in the anionic doublet state and silyl‐amidine groups in the cationic doublet state. This may be due to the electron‐deficient nature of olefin and electron‐rich N‐donating functional groups on silicon atoms. Compound 2 displays unprecedented chemical bonding in this class of compounds as predicted by EDA‐NOCV calculations. We have also compared the bonding situation of compound 2 with a previously reported compound 3.

Herein, we report a silylene‐functionalized C4‐cumulene (2) and investigate its bonding scenario employing computational methods such as NBO analysis, AIM, and energy decomposition analysis‐natural orbital for chemical valence (EDA‐NOCV). The EDA‐NOCV analysis showed that compound 2 prefers to possess electron‐sharing covalent sigma and dative covalent sigma bonds (Si↔C and C→Si) between Ph2C4 fragment in the anionic doublet state and silyl‐amidine groups in cationic doublet state. This may be due to the electron‐deficient nature of olefin and electron‐rich N‐donating functional groups on silicon atoms. Compound 2 displays unprecedented chemical bonding in this class of compounds as predicted by EDA‐NOCV calculations. We have also compared the bonding situation of compound 2 with a previously reported compound 3.