New N-heterocyclic plumbylenes (NHPbs) and their complexes with palladium and platinum by DFT

Following our quest for stable group 14 divalents, novelN-heterocyclic plumbylenes (NHPbs), composed of 2,4,6-cycloheptatriene-2,7-diazaplumbylene (1), benzannulated with one (2), two (3,4), and three benzene rings (5), are compared and contrasted at the density functional theory level. Results indicate that in going from 1 to 5, the absolute values of singlet-triplet energy gap (Delta Es-t) and band gap (Delta EH-L) increase, while nucleophilicity (N), electrophilicity (omega), and chemical potential (mu) decrease. The most benzannulated structure, ([a,c,e]tribenzo)cyclohepta-2,7-diazaplumbylene (5), turns out as the most stable plumbylene for showing the most negative Delta Es-t of - 194.94 kcal/mol. Furthermore,5shows the highest Delta EH-L(- 2.75 eV), with the lowest N(1.31 eV), omega(8.20 eV), mu(- 7.15 eV), and charge of (+ 0.736) on Pb atom. Isodesmic reactions of1-5with common transition metal halides, MX2, give forty new metal complexes of 1(M-X)-5(M-X), where M = Pt and Pd, while X = F, Cl, Br, and I. Their complexation energies (Delta E-Com) indicate that1-5are rather stronger ligands with Pt than Pd. Bader's atoms in molecules (AIM) and NBO analyses show the partial covalent and partial electrostatic nature of Pb-M bonds.