Structural variation in silver acetylide complexes: Syntheses and X-ray structure determinations of [Ph(3)PAgC CPh](4)center dot 3.5THF and [Me(3)PAgC CSiMe(3)](infinity)

[Ph(3)PAgC=CPh](4) . 3.5THF (2) can be prepared by the reaction of CpAgPPh(3) (1) with lithium phenylacetylide (1:1 equiv), Similarly [Me(3)PAgC=CSiMe(3)]infinity (4) can be prepared by the reaction of CpAgPMe(3) (3) and lithium (trimethylsilyl)acetylide (1:1 equiv). Both complexes have been characterized by elemental analyses, solid-state IR spectroscopy, H-1 and P-31 NMR spectroscopy, and low-temperature X-ray diffraction studies, The structure of 2 consists of a tetranuclear ''flat-butterfly'' core, with the two ''hinge'' silver atoms sigma-bonded to two acetylide fragments, which then pi-complex the apical Ag(PPh(3))(2) fragments, In 4, the smaller steric bulk of the phosphine employed allows this complex to crystallize as a polymer, Rather than being constructed from simple [R(3)PAg(acetylide)] units, both 2 and 4 are formed by the aggregation of(acetylideAg- and Ag(PR(3))(2)(+) fragments. The preparation of complexes 2 and 4 demonstrates the synthetic utility of nucleophilic substitution of CpAgPR(3) in the synthesis of Ag organometallics, The different structural alternatives adopted by 2 and 4 point to the steric bulk of the phosphine ligands being the major influence on the structure of Ag acetylide complexes.