Insertion reaction between planar chiral cyclopalladated derivatives of ferrocene and diphenylacetylene

The reaction between diphenylacetylene and the planar chiral halogeno-bridged cyclopalladated compounds of ferrocene, [Pd{(eta(5)-C5H3C(CH3)=NNCH2CH2CH2CHCH2OCH3)Fe(eta(5)-C5H5)}(mu-X)](2) [X = Cl: syn-(-)-(S-p,R,R,S-p)-1, syn-(-)-(R-p,R,R, R-p)-1, syn-(+)-(R-p,S,S,R-p)-1 and syn-(-)-(S-p,S,S,S-p)-1; X = Br: symz-(-)-(S-p,R,R,S-p)-2, syn-(-)-(R-p,R,R,R-p)-2, syn-(+)-(R-p,S,S,R-p)-2 and syn-(-)-(S-p,S,S,S-p)-2], afforded monomeric products in which one or two alkynes had been inserted into the Pd-C bond. Mono-insertion of alkyne occurred when reacting these compounds with stoichiometric amounts of diphenylacetylene, whereas bi-insertion was achieved with excess diphenylacetylene. The structures of mono-insertion compounds [PdX(eta(5)-C5H3(PhC=Ph)C(CH3)=NNCH2CH2CH2CHCH2OCH3)Fe(eta(5)-C5H5)] X = Cl: (-)-S-p,S)-3; X = Br: (-)-(S-p,S)-4] and bi-insertion compounds [PdX(eta(5)-C5H3 {eta(3)-(PhC=C(Ph)-(Ph)C=CPh)}C(CH3)=N NCH2CH2CH2CHCH2OCH3)Fe(eta(5)-C5H5)] [X = Cl: (-)-(S-p,R)-5, (+)-(R-p,S)-5; X = Br: (-)-(S-p,R)-6, (+)-(R-p,R)-6] have been determined by single-crystal X-ray analysis. (C) 1999 Elsevier Science S.A. All rights reserved.