- No file added yet -
Rigid-Rod Polymers, Oligomers, and Model Complexes with Pt−Pt Bonds in the Backbone
journal contribution
posted on 1996-12-10, 00:00 authored by Michael J. Irwin, Guochen Jia, Jagadese J. Vittal, Richard J. PuddephattReaction of
[Pt2Cl2(μ-dppm)2], dppm
= Ph2PCH2PPh2, with
PhC⋮CH in methanol gives
[Pt2Cl2(μ-dppm)2(μ-PhCCH)],
1, or, in the presence of base,
[Pt2(C⋮CPh)2(μ-dppm)2],
2, or
[Pt2(C⋮CPh)2(μ-dppm)2(μ-PhCCH)],
4. Complex 2 reacts with chlorinated
solvents to re-form
[Pt2Cl2(μ-dppm)2],
but in the presence of base,
[Pt2(C⋮CPh)2(μ-dppm)2(μ-OH···Cl)],
3,
may be formed. Complexes 1 and 3 have been
characterized by X-ray structure determinations, and the conditions for formation of 2 have been
optimized as a model reaction for
polymer formation by using diacetylenes. Reaction of
[Pt2Cl2(μ-dppm)2]
with HC⋮CArC⋮CH
in methanol in the presence of base gives insoluble oligomers
characterized as Cl-[Pt2(μ-C⋮CArC⋮C)2(μ-dppm)2]x[Pt2Cl(μ-dppm)2],
5, that is as a diacetylide bridged oligomer
with
chloride end groups; depending on the diacetylide used x
varies from ca. 3−12. Cationic
polymers
[Pt2(μ-dppm)2(μ-L-L)]x(BF4)2x,
6 or 7, are formed by reaction of
[Pt2Cl2(μ-dppm)2]
with diisocyanide ligands C⋮NArN⋮C or with the diphosphine ligand
Ph2PC6H4PPh2,
respectively. In contrast, the diphosphine ligand
i-Pr2PC6H4C6H4P-i-Pr2,
having a longer
spacer group, gives the cyclic complex
[Pt2(μ-dppm)2(μ-i-Pr2PC6H4C6H4P-i-Pr2)]2(BF4)4.
The
polymeric complexes 5−7 are insoluble or
sparingly soluble in common organic solvents.
They represent rare examples of conjugated, rigid-rod oligomers or
polymers with metal−metal bonds in the backbone.
