Diphenylacetylene and acetylene derivatives of tridecacarbonyltrimethylphosphinetetraosmium

This thesis presents the synthesis and characterization of seven new tetraosmium-alkyne clusters. These clusters are derived from reactions of diphenylacetylene or acetylene with tridecacarbonyltrimethylphosphinetetraosmium. Reactions between C2Ph2 and Os4(CO)13(PMe3) have produced three new compounds: two isomers of Os4¬(μ4-η2-C2Ph2)(CO)11(PMe3) with a trimethylphosphine located on the “wingtip” or “hinge” Os atoms of the osmium core and; Os4(μ3-η2-C2Ph2)(CO)12(PMe3), which is the precursor to the “wingtip” isomer. Three synthetic routes are reported to produce Os4(μ3-η2-C2Ph2)(CO)12(PMe3), one route includes an interconversion between a four- and three- coordinate alkyne. Four new clusters have been characterized from the reaction of C2¬H2 and Os4(CO)13(PMe3). Of these, Os4[μ3-η2-(H)CC(H)}C(O)](CO)12(PMe3) has two isomers and exhibits an unusual bonding moiety, involving a coordinated alkyne bound to a carbonyl ligand; forming an alkyne bridging two Os atoms and a ketone functional group bound to a third Os. The other two clusters, Os4(μ3-η2-C2H2)(CO)12(PMe3) and Os4(μ4-η2-C2H2)(CO)11(PMe3), were produced by the systematic removal of carbonyl ligands.