Activation of Tri(2-furyl)phosphine by [Ru₄(<i>μ</i>-H)₄(CO)₁₂]: The First Example of Coordinated Furyl and Furyne Ligands at Tetraruthenium Phosphide and Phosphinidene Clusters

Tri(2-furyl)phosphine (PFu3) reacts with [Ru4(μ-H)4(CO)12] (1) in refluxing THF to give, apart from an isomeric pair of the substituton products [Ru4(μ-H)4(CO)10(PFu3)2] (2a and 2b), the μ-phosphido cluster [Ru4(μ-H)2(CO)8(PFu3)2(μ-PFu2)(μ-η1,η2-C4H3O)] (3) and a series of μ3- and μ4-phosphinidene clusters [Ru4(μ-H)2(CO)12-x(PFu3)x(μ3-PFu)] (x = 0 (4), 2 (5), 3 (6)) and [Ru4(μ-H)2(CO)9(PFu3)2(μ4-PFu)(μ3-η1,η1,η2-C4H2O)] (7). In this one-pot reaction, the excellent facility for PFu3 to act as rich sources of furyl, furyne, phosphide (μ-PR2), and phosphinidene (μ3-PR and μ4-PR) fragments on tetrametallic frameworks has been demonstrated. The single-crystal X-ray structures of all new molecules have been determined. The structure of 7 represents the first structurally characterized example of stable furyne-containing cluster complexes of ruthenium. The electrochemical behavior and molecular orbital calculations of these metallophosphorus clusters have been examined as a function of the coordination modes of the phosphorus-containing moieties.