Carbon-free D4h [Znn(P4)2]2− and [Znn(P4)2]Li2 (n = 2–5): Novel multimetal sandwich complexes

A density functional theory investigation on the possibility of carbon-free multimetal sandwich D4h [Znn(P4)2]2− and [Znn(P4)2]Li2 (n = 2–5) complexes has been performed in this work. The equilibrium geometries, electronic structures, vibrational frequencies, and stabilities of these complexes are researched by B3LYP and BP86 methods at 6-311+G(3df) levels of theory. The series of multimetal sandwich complexes with D4h symmetry are all true minima on the potential energy surface. Natural bond orbital (NBO) analyses for the series of complexes reveal that the Zn–Zn bonds of the title complexes are all typical covalent single bonds, while the bonding between P42− ligands and Znn2+ (n = 2–5) nuclear is mainly ionic. The P–P distance in these complexes is slightly elongated with respect to that in the isolate P42−. These novel multimetal sandwich complexes turn out to be strongly thermodynamically favored in the gas phases and may be targeted in future experiments to expand the structural domain of sandwich-type complexes.