Carbon–arsine and carbon–antimony bonds activation of AsPh3 and SbPh3 at dimanganese and dirhenium centers in bimetallic clusters
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The reactivity of [M 2 (CO) 8 (NCMe) 2 ] (Mn, Re) with EPh 3 (E = As, Sb) has been illustrated. Bimetallic manganese-arsenic complexes, [Mn 2 (CO) 7 (µ-AsPh 2 )(AsPh 3 )(µ-H)] ( 1 ) and [Mn 2 (CO) 8 (µ-AsPh 2 ) 2 ] ( 2 ) were produced from the reaction of [Mn₂(CO) 8 (NCMe) 2 ] with AsPh 3 in refluxing toluene. The controlled experiment shows that 1 is a precursor of 2 . It can be speculated that activation of one phenyl group from the coordinated AsPh 3 of 1 formed a second bridging (µ-AsPh 2 ) ligand. The cleaved phenyl group most probably combines with the departed edge-bridging hydride to produce benzene as a byproduct. In contrast, a similar reaction with SbPh 3 gave [Mn 2 (CO) 8 (µ-SbPh 2 ) 2 ] ( 3 ) as the sole product. On the other hand, identical reaction of [Re₂(CO) 8 (NCMe) 2 ] and AsPh 3 resulted a new type of rhenium-arsenic bimetallic complex [Re 2 (CO) 5 (σ-Ph)(µ-MeCO 2 )(µ-AsPh 2 ) 2 ] ( 5 ) along with two previously reported hydride compounds [Re 2 (CO) 6 (AsPh 3 ) 2 (µ-AsPh 2 )(µ-H)] ( 4 ) and [Re(CO) 4 (AsPh 3 )H] ( 6 ). The coordination mechanism of the µ-MeCO 2 ligand is unknown, as the source of MeCO 2 is unpredictable. However, we have observed similar incidents in Os 3 -dithiocarbamate chemistry. At this end, we believe C–CN bond activation, followed by a coupling of a CO 2 molecule from the atm osphe re, produces MeCO 2, which is a four-electron donor ligand. Molecular structures of the new products 1 , 3 , and 5 were unambiguously established through spectroscopic data and single-crystal X-ray diffraction studies. The bonding in these new complexes has been examined by density functional theory (DFT) calculations.
