EDA-NOCV Analysis of Donor-Base-Stabilized Elusive Monomeric Aluminum Phosphides [(L)P-Al(L'); L, L' = cAAC Me , NHC Me , PMe 3 ].

Herein, we report on the stability and bonding analysis of donor-base-stabilized monomeric AlP species ( 1 - 6 ) of the general formula (L)P-Al(L'); [L = cAAC Me , L' = cAAC Me , NHC Me , PMe 3 , (N i Pr 2 ) 2 ( 1-4 ); L = L' = NHC Me , PMe 3 ( 5 and 6 ); cAAC = cyclic alkyl(amino) carbene; NHC = N -heterocyclic carbene]. Energy decomposition analysis coupled with natural orbitals for chemical valence (EDA-NOCV) analysis indicates the synthetic viability of this class of species, stabilized in their singlet ground state, in the laboratory. The C L -P bond is found to be a partial double bond (WBI ∼ 1.45), while the C L /P L -Al bond is a single bond (WBI ∼ 0.42-0.69). These bonds are mostly covalent or dative σ/π bonds depending upon the ligands attached. The central P-Al bond is an electron-sharing covalent polar single bond (WBI ∼ 0.80; P-Al) for 1-4 and a dative σ bond for 5 and 6 (WBI ∼ 0.89-0.93; P-Al). The calculated intrinsic interaction energies of the central P-Al bonds are found to be in the range from -116 to -216 kcal/mol ( 1 - 3 and 5 and 6 ). This value is the highest for compound 3 , possibly due to the push and pull effects from the ligands PMe 3 and cAAC, respectively.