Carbon-Phosphorus Bond Activation of Tri(2-thienyl)phosphine at Dirhenium and Dimanganese Centers

Reaction of [Re-2(CO)(9)(NCMe)] with tri(2-thienyl)phosphine (PTh3) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re-2(CO)(9)(PTh3)] (1), [Re-2(CO)(8)(NCMe)(PTh3)] (2), and [Re-2(CO)(8)(PTh3)(2)] (3). Complex 2 was also obtained from the room-temperature reaction of [Re-2(CO)(8)(NCMe)(2)] with PTh3 and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene affords [Re-2(CO)(8)(mu-PTh2)(mu-eta(1):kappa(1)-C4H3S)] (4) and [Re-2(CO)(7)(PTh3)(mu-PTh2)(mu-H)] (5), respectively, both resulting from carbon-phosphorus bond cleavage of a coordinated PTh3 ligand. Reaction of [Re-2(CO)10] and PTh3 in refluxing xylene gives a complex mixture of products. These products include 3-5, two further binuclear products, [Re-2(CO)(7)(PTh3)(mu-PTh2)(mu-eta(1):kappa(1)-C4H3S)] (6) and [Re-2(CO)(7)(mu-kappa(1):kappa(2)-Th2PC4H2SPTh)(mu-eta(1):kappa(1)-C4H3S )] (7), and the mononuclear hydrides [ReH(CO)(4)(PTh3)] (8) and trans-[ReH(CO)(3)(PTh3)(2)] (9). Binuclear 6 is structurally similar to 4 and can be obtained from reaction of the latter with 1 equiv of PTh3. Formation of 7 involves a series of rearrangements resulting in the formation of a unique new diphosphine ligand, Th2PC4H2SPTh. Reaction of [Mn-2(CO)(10)] with PTh3 in refluxing toluene affords the phosphine-substituted product [Mn-2(CO)(9)(PTh3)] (10) and two carbon-phosphorus bond cleavage products, [Mn-2)(CO)(6)(mu-PTh2)(mu-eta(1):eta(5)-C4H3S)] (11) and [Mn-2(CO)(5)(PTh3)(mu-PTh2)(mu-PTh2)(mu-eta(1):eta(5)-C4H3S)] (12). Both 11 and 12 contain a bridging thienyl ligand that is bonded to one manganese atom in a eta(5)-fashion. The molecular structures of eight of these new complexes were established by single-crystal X-ray diffraction studies, allowing a detailed analysis of the disposition of the coordinated ligands.