The theoretical study on nickel(II) amide complexes of carbon and carbene: new suggested molecules as fertilizers for plants

Nguyen Thi Ai Nhung, Huynh Thi Phuong Loan, Le Thi Hoa, Tran Thai Hoa, Tran Duong, Vo Van Tan, Dang Tan Hiep, Pham Van Tat, Duong Tuan Quang

Abstract


Quantum chemical calculations at the gradient-corrected (BP86) density-functional theory (DFT) with various basis sets (SVP, TZVPP, TZ2P+) are carried out to calculate for the first time the bonding situation of nickel(II) amidecomplexes of carbon Ni(NH2)2–C(PH3)2 (Ni2-CP2) and carbene Ni(NH2)2–NHCMe (Ni2-NHCMe). The nature of the (NH2)2Ni–C(PH3)2 and (NH2)2Ni–NHCMe bonds was analyzed with charge- and energy decomposition methods. The calculated equilibrium structure of carbon complex Ni2-CP2 shows that ligand C(PH3)2 (CP2) are bonded in a tilted orientation relative to the fragment Ni(NH2)2 with the bending angle, α, of Ni2-CP2 is 146.1°. In contrast to this, the carbene complex Ni2-NHCMe possesses end-on-bonded NHCMe ligand with the bending angle, α, is 180°. The bond dissociation energy (BDE) for the Ni2-CP2 bond is slightly higher than for the Ni2-NHCMe bond. The low-valent chemistry of nickel(II) amide in Ni2-CP2 always receives electrons from the s lone-pair orbital of C(PH3)2 and the Ni-C bond has a small contribution from (NH2)2Ni←C(PH3)2 π-donation. Although the carbon ligand has two lone-pairs orbitals for donation but the structure of carbon complex exhibits an unusual bonding at nickel(II) amide fragment. The EDA-NOCV results suggest that the CP2 ligand in the Ni2-CP2 is very strong s-donor and strong π-donor. The NHCMe ligand has only one lone pair for donation and the NHCMe ligand in the Ni2-NHCMe is strong s-donor and strong π-donor. The first results of this work not only give details the structures and chemical bonding of the molecules investigated, but also open up a field of research in the preparation of new molecules as fertilizers for plants.

Keywords. Carbon, carbene, BDE; DFT; Bond dissociation energies (BDEs); Energy decomposition analysis (EDA); Natural Orbitals for Chemical Valence (NOCV).

Keywords


Carbon, carbene, BDE; DFT; Bond dissociation energies (BDEs); Energy decomposition analysis (EDA); Natural Orbitals for Chemical Valence (NOCV).