H2S gas interaction with Pt(II)-containing polymetallaynes of selected chain length: an XPS and EXAFS study

The interaction between gaseous H2S and the surface of several metal-containing oligomers, investigated by emission and absorption spectroscopies, is presented and discussed. The polymetallayne trans-{Cl-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]9Pt(PBu3)2Cl} and related model molecules, i.e. the binuclear transition metal dialkynyl bridged Pt(II) square planar complex trans, trans-[ClPt(PBu3)2(CC-C6H4-C6H4-CC)Pt(PBu3)2Cl], the tetranuclear linear oligomer trans-{Cl-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]3Pt(PBu3)2Cl}, the tetranuclear cyclic oligomer cis-[Pt(PBu3)2(CC-C6H4-C6H4-CC)]4, were exposed to hydrogen sulfide and then investigated by X-ray photoelectron (XPS) and X-ray absorption (XAS) spectroscopies, in order to shed light on the gas/polymer interaction associated to the sensing properties of these materials. XPS measurements evidenced the presence of S in the polymetallayne samples exposed to H2S, and the measured S2p binding energy values correlate with H2S adsorbed by means of sulfur atoms chemically bonded to metal atoms, owing to the formation of sulfur-containing adducts. XAS data analysis suggested a square-pyramidal geometry around the transition metal with H2S in the apical position for the pentacoordinated platinum units.