Evaluation of the σ‑Donation from Group 11 Metals (Cu, Ag, Au) to Silane, Germane, and Stannane Based on the Experimental/Theoretical Systematic Approach

Reactions of group 11 metal chlorides (CuCl, AgCl, AuCl) with {(o-Ph2P)­C6H4}3E­(F) (E = Si (1), Ge (2), Sn (3)) provide a complete series of metallasilatrane [{(o-Ph2P)­C6H4}3(F)­Si]­MCl (E = Cu (4), Ag (5), Au (6)), metallagermatrane [{(o-Ph2P)­C6H4}3(F)­Ge]­MCl (E = Cu (7), Ag (8), Au (9)), and metallastannatrane [{(o-Ph2P)­C6H4}3(F)­Sn]­MCl (E = Cu (10), Ag (11), Au (12)) complexes. Structural analyses clearly show the presence of M→E interactions in all of these complexes and establish the presence of periodicity; heavier group 14 elements E act as stronger electron acceptor ligands, and heavier group 11 metals exhibit higher donor ability toward ER4. Density functional theory calculations fully support these trends and suggest that σ-acceptor ability of saturated (four-coordinate) heavier group 14 element compounds toward group 11 metals is related to σ*­(E–F) molecular orbital levels, which mainly depend on the deviation of the geometry around E from tetrahedral geometry to trigonal bipyramidal.