Synthesis, characterization, and theoretical studies of new alkynylferrocene and -biferrocene ligands and their platinum-containing dimers and oligomers

A series of disubstituted alkynylferrocenyl and -biferrocenyl ligands (1-4) have been synthesized and these then utilized to form a number of di-, tri -, and oligomeric platinum-containing alkynyl species (5-10). Characterizat ion by spectroscopy and X-ray crystal structure determinations of [{C5H4FeC 5H4C drop CH}(2)] (3), [C6H5{(C2H5)(3)P}(2)PtC drop CC5H4-FeC5H4C drop CPt{ P(C2H5)(3)}(2)C6H5] (5), and [(C6H5Pt{P(C2H5)(3)}(2)C drop C{C5H4Fe(C5H4)(2 )FeC5H4}C drop CPt{P(C2H5)(3)}(2)C6H5)] (8) illustrates their "rigid-rod" s ymmetrical geometries, featuring staggered cyclopentadienyl rings and almos t perfect anti geometry of the ethynyl linkages in each case. Electrochemic al and theoretical (extended Huckel calculations) studies on the metal comp lexes indicate that there is no metallocene-metallocene interaction through the alkynyl-platinum bridges.