The Potential of Molybdenum Complexes Bearing Unsubstituted Heterodiatomic Group 15 Elements as Linkers in Supramolecular Chemistry

Abstract

The reactions of tetrahedral molybdenum complexes bearing unsubstituted heterodiatomic Group 15 elements, [Cp₂ Mo₂ (CO)₄ (μ,η² :η² -PE)] (Cp=C₅ H₅ ; E=As (1), Sb (2)), with Cu^I halides afforded seven unprecedented neutral supramolecular assemblies. Depending on the Mo₂ PE units and the Cu^I halide, the oligomers [⟨{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η² :η¹ -PE}⟩₄ ⟨{CuX}{Cu(μ-X)}⟩₂ ] (E=As (X=Cl (3), Br (4)); E=Sb (X=Cl (6), Br (7))) or the 1D coordination polymers [{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η¹ :η¹ -PAs}{Cu(μ-I)}]_n (5) and [{Cp₂ Mo₂ (CO)₄ }{μ₄ ,η² :η² :η² :η¹ -PSb}₂ {Cu(μ-X)}₃ ]_n (X=I (8), Br (9)) are accessible. These solid-state aggregates are the first and only examples featuring the organometallic heterodiatomic Mo₂ PE complexes 1 and 2 as linking moieties. DFT calculations demonstrate that complexes 1 and 2 present a unique class of mixed-donor ligands coordinating to Cu^I centers via the P lone pair and the P-E σ-bond, revealing an unprecedented coordination mode.

Keywords: antimony; arsenic; copper; heterodiatomic units; phosphorus.