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Redox condensation of PPN[Mn2(CO)8(μ-PPh2)] (1; (PPN = N(PPh3)2) with Au2Cl2(μ-P−P) (P−P = (C5H4PPh2)2Fe (dppf), Ph2PC2H4PPh2 (dppe)) gives two hexanuclear Au−Mn clusters [AuMn2(CO)8(μ-PPh2)]2(μ-P−P) (P−P = dppf, (2), dppe (4)), both of which contain a diphosphine bridging two Mn2Au triangles. Complex 2 is formed via an intermediate, AuCl(μ-dppf)[AuMn2(CO)8(μ-PPh2)], (3), which was isolated. Bridge cleavage of 2 occurs at thf reflux with PPh3 and room temperature with P(OEt)3 to give the triangular clusters [(PR3)AuMn2(CO)8(μ-PPh2)] (R = Ph (5), OEt (6)), respectively. The latter exchange of dppf with P(OEt)3 is reversible in solution. Condensation of 1 with AuCl(SMe2) gives an anionic pentanuclear cluster, PPN[Au{Mn2(CO)8(μ-PPh2)}2] (7). Complexes 2 and 7 were structurally characterized by single-crystal X-ray diffractometry. Complex 2, which is centrosymmetric with Fe in dppf at a crystallographic inversion center, consists of a ferrocenylphosphine bridging two heterometallic triangles (Au−Mn = 2.660(1) and 2.776(1) Å; Mn−Mn = 3.049(2) Å). Complex 7 is made up of two planar AuMn2P metallacycles fused at Au at an angle of 85.50(4)°. With crystallographic C 2 symmetry, a twisted-bowtie skeleton resulted with gold at its center. Both Au−Mn (mean 2.806(1) Å) and (PPh2-bridged) Mn−Mn (3.105(2) Å) lengths are significantly longer than those in 2. The Mn−Mn bond of 2 is also significantly longer than that of 1. Fenske−Hall MO calculations on 1, 2, and 7 together with Mn2(CO)8(μ-H)(μ-PPh2) (8) and (PPhMe2)AuMn2(CO)8(PPh2) (9) indicate that aside from 1, all the complexes, including 2 and 7, give a negative overlap population in the Mn−Mn interactions. The Mn−Mn distance appears to be determined by the strength of the AuMn2 interaction and/or the size of H compared to Au. The weaker Mn−Mn and Au−Mn interactions in 7 (as compared to those in 2 and 9, respectively) are likely to be caused by the absence of Au orbital reinforcement in the direction of the Mn2 moiety as a consequence of symmetry.

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Oxidative decarbonylation of Re2(CO)10 by Me3NO in a mixture of THF and MeOH followed by addition of alkyl-chained diphosphine Ph2P(CH2) n PPh2 (PP) (n = 1−4) gives Re2(μ-OMe)2(μ-PP)(CO)6 in 34, 29, 28, and 10% yields, respectively. This methanolytic oxidation across the Re−Re bond provides a general and one-step route for the synthesis of these dirhenium hexacarbonyl complexes with diphosphine and methoxo bridges. The molecular structure of Re2(μ-OMe)2(μ-Ph2PCH2PPh2)(CO)6 was determined by single-crystal X-ray diffraction analysis. It contains two fac-[Re(CO)3] moieties bridged by dppm and two methoxo ligands. The {Re2O2} core is significantly more planar than that in the Fe(C5H4PPh2)2 analogue. That such a dinuclear core is maintained in spite of the different steric demands of the different bridging diphosphines illustrates the great geometric tolerance of the bridging methoxo groups. The fluxionality of the dppm, dppe, and dppp complexes has been studied and compared by molecular modeling and solution 1H NMR spectroscopy. Dynamic laser-light scattering (DLS) shows that the dppe complex aggregates in CH2Cl2 to form small clusters with an average radius of ∼370 nm. The use of a combination of DLS and NMR in organometallic chemistry is unprecedented.