The first water soluble metal-enediyne complexes: Structural characterization of trans-[Os(en)(2)(eta(2)-L)Br](+) Br- (en equals ethylenediamine, L equals cis-1,6-bistrimethylsilyl-3-ene-1,5-diyne)

The first water soluble metal-enediyne complexes have been prepared by displacement of the dihydrogen ligand of [Os(II(en)(2)(eta(2)-H-2)(H2O)](OTF)(2) (en = ethylenediamine, OTf = CF3SO3-), 1, with an enediyne molecule, cis-l,6-bistrimethylsilyl-3-ene-1,5-diyne, 2. Different a donor ligands can be introduced to the trans position of the enediyne ligand to prepare different metal-enediyne complexes. The single crystal X-ray analysis of trans-[Os(en)(2)(eta(2)-L)Br](+) Br- (L = cis-1,6-bistrimethylsilyl-3-ene-1,5-diyne), 4, shows that the osmium(II)(en)(2) moiety binds specifically to the double bond of the enediyne molecule. This structure represents a new mode of metal-enediyne coordination, 4 crystallizes in the monoclinic space group P2(1)/a, with Z = 4, a = 13.150(2) Angstrom, b = 11.384(4)Angstrom, c = 18.413(9)Angstrom, and beta = 100.74(2)degrees. The structure was solved by direct methods and refined to conventional agreement indices R = 0.054 and R(w) = 0.048 with 2880 unique reflections for which I > 3 sigma(I).