Stereoregular Polymerization of Phenylacetylenes Catalyzed by [Hydridotris(pyrazolyl)borato]rhodium(I) Complexes

Abstract

Rhodium(I) tris(pyrazolyl)borate complexes TpR2Rh(cod) (R = Me, Ph, i-Pr) were found to serve as efficient catalysts for highly stereoregular polymerization of phenylacetylene derivatives (p-YC6H4C⋮CH; Y = H, Me, Cl, CN, CO2Me, COMe, NO2) to give poly(phenylacetylene) species having a head-to-tail, cis-transoidal structure. The catalytic activity was strongly affected by the substituents (R) at the 3- and 5-positions of the pyrazolyl groups, and the more sterically demanding R groups led to higher catalytic activity.

Diversity in Complexation of [RhI(cod)]+ and [IrI(cod)]+ by Pyridine-Amine-Pyrrole Ligands

“…The activity of 5 in polymeristo be essential for its catalytic activity in the polymerisation ation of phenylacetylene also reflects the occurrence of of phenylacetylene. [9] In accordance with this we observed κ 2 Ϫκ 3 isomerism. L Bzl Ϫ in 6, the Ir-analogue of 5, shows that rhodium complex 5, but not iridium complex 6, is an no sign of pyramidal inversion of N Bzl amine via κ 2 Ϫκ 3 isomactive catalyst for the polymerisation of phenylacetylene erism in solution, and is tridentate in the solid state.…”

“…The mo-coordination of N Py , and thus results in five coordination. lecular mass (M n ) and the high stereoregularity (head-totail cis-transoidal structure) of the obtained poly(phenylacetylene) are similar to those of poly(phenylacetylene) pre-Experimental Section pared with (Tp R2 )Rh I (cod) [9] and other rhodium cataGeneral Methods: All reactions were performed under a nitrogen lysts.…”

Polymerization of phenylacetylene catalysed by RhTp(cod) and RhBp(cod) in ionic liquids: effect of alcohols and of tetraammonium halides

“…12 We have found that ionic liquids, as well as ammonium salts, are efficient co-catalysts, especially in polymerization catalysed by RhTp(cod) (1). Very good results have also been obtained with alcohols as solvents.…”

“…5 Rhodium(I) tris(pyrazolyl)borate complexes with homoand hetero-scorpionates, RhTp (cod), are efficient catalysts of stereoregular polymerization of phenylacetylene derivatives. 12,13 Catalytic activity has been observed only for complexes with substituents (R) in the 3-and 5-positions of the pyrazolyl ring, and the more bulky R-groups usually cause higher catalytic activity. In contrast, rhodium complexes with unsubstituted tris(pyrazolylborate) (Tp) and bis(pyrazolylborate) (Bp) ligands (RhTp(cod) (1), RhBp(cod) (2); Fig.…”

“…1) have, till now, been known as almost inactive. 12 In this paper we describe two rhodium(I) pyrazolyl borates, 1 and 2, as active catalysts when used in ionic liquids or with tetraammonium salts as co-catalysts and alcohols as solvents. The aim of the studies presented in this paper was to construct an active catalytic system for the polymerization of phenylacetylene (Scheme 1) based on rhodium complexes, RhTp(cod) (1) and RhBp(cod) (2).…”