Synthesis and characterization of bis(η2-alkyne)dihalogeno-mercury(II) compounds: Crystal structure of [NBu4]2-[{cis-Pt(C6F5) 2(C≡CSiMe3)2}HgBr 2]·CH2Cl2

The reactions of [NBu4]2[cis-Pt(C6F5)2(C[triple bond, length half m-dash]CR)2](R = But or SiMe3) with HgX2(X = Cl, Br or I) in a 1:1 molar ratio afforded the simple monomeric bis(η2-alkyne)mercury(II) compounds [NBu4]2[{cis-Pt(C6F5)2(C[triple bond, length half m-dash]CR)2}HgX2](R = But or SiMe3; X = Cl, Br or I) in which both alkyne units are co-ordinated η2 side-on to the precursor mercury(II) halides. Similar treatment of [NBu4]2[Pt(C[triple bond, length half m-dash]CR)4]·2H2O (R = But or SiMe3) with HgX2 in a 1:2 molar ratio gave the corresponding trinuclear 1:2 adducts. All the complexes have been characterized by analytical and spectroscopic data and, in addition, the molecular structure of [NBu4]2[{cis-Pt(C6F5)2(C[triple bond, length half m-dash]CSiMe3)2}HgBr2]·CH2Cl2 has been determined by X-ray diffraction methods. The structure of the anion shows that the HgBr2 unit is attached to the dianionic fragment [Pt(C6F5)2(C[triple bond, length half m-dash]CSiMe3)2]2– only through η2 side-on co-ordination of the two (trimethylsilyl)ethynyl ligands. The platinum–mercury distance is 3.627(1.5)Å.We thank the Spanish Comision Interministerial de Ciencia y Tecnologia (CICYT) for financial support (Project PB92-0364) and for research grants (to J. R. B. and A. M.).Peer reviewe