The Wonder of Palladium Catalysis: From Carbon-Carbon to Metal-Carbon Bond Formation. An Opportunity of Getting Astonishment from Reality

Abstract

By the use of the Stille coupling it has been possible to assemble a variety of acetylene and (Z)-1,3-enyne bridged bis(cyclopentadienyl) metal complexes. In the course of these studies it was accidentally found that palladium can also promote the formation of metal-carbon bonds. By combining these two procedures a variety of polymetallaacetylide blocks and tethers can be formed. A new one pot procedure from aromatic iodides to ethynylstannanes offers a convenient access to polyacetylene and polymetallaacetylene polymers.

Preparation of models and oligomers of metal alkynyls

“…Even the addition of a larger amount of Pd catalyst to the reaction mixture did not improve the yield; in some cases a reverse effect was observed, in fact [10]. Indeed, it has not been possible so far to achieve the selective formation of either mono-(6, 7) or di-substituted (4,5) products. It is very likely that Pd(PPh 3 ) 4 catalyses the transformations of 2Á/3 into 6 Á/7 and of 6 Á/7 into 4Á/5 as well as the reverse processes.…”

“…Since metallaacetylide moieties can be prepared by coupling of metal-halides and trialkyltinacetylides by palladium catalysis [5], we have focussed our attention on the possibility of extending the EOP method to the preparation of ethynylaromatic Á/ethynylmetallo copolymers [Ã/C Å/C Ã/Ar Ã/C Å/C Ã/M(L) m Ã/] n , as indicated in path a 2 of Fig. 1.…”

An efficientone-pot access to poly(arylene ethynylene) homopolymers: Use of the Bu3Sn?moiety as a recyclable carrier to introduce the ethynyl unit into the chain

“…Conjugated poly(arylene ethynylene) polymers constitute a particularly interesting subset of this class of materials, because the spacing of the aromatic moieties with the electron‐rich acetylide moiety should enhance both electron density and conjugation—thus delocalization—throughout the polymer chain and, consequently their related properties. Within this frame, in the last few years we became interested in the study of palladium catalyzed processes to improve methods and to disclose new approaches to highly ethynylated materials 2…”

The luminescent and scintillation properties of YAlO3 and YAlO3:Ce single crystalline films grown by liquid phase epitaxy from BaO‐based flux

“…Fischer and co‐workers126, 127 have also utilized similar Stille‐coupling techniques to form heterobimetallic complexes with propynylidene and pentadiynylidene bridges (see Section 8). The role of palladium catalysis in CC and MC bond formation, with particular focus on alkynes, was well summarized by Lo Sterzo in 1999 128…”