177 Journal of Organometallic Chemistry, 379 (1989) 177-185 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands JOM 20330 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Insertions of diphenylacetylene into cyclopalladated compounds. Crystal structure of [Pd{ (PhC=CPh),C,H,CH,N=CH(2,6-C6HJC12)} zyxwvutsrqponmlkjihgfedcbaZYXWVU B r] Joan Albert, Jaume Granell, Joaquim Sales Departament de Quimica Inorgcinica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain) and Xavier Solans Departamen t de Cristal. logrufia, Mineralogia i Dip&its Minerals, Uniuersitat de Barcelona, Marti i Franq&s s/n 08028 Barcelona (Spain) (Received July 21st, 1989) Abstract The reaction between [Ph{C,H,CH,fi=CH(2,6-C,H,Cl,)}Br], and PhC=CPh gives the bis-insertion compound [Pd{(PhC=CPh),C,H,CH,N=CH(2,6-C,H,CI, } Br] in good yield. This compound crystalliz!s in the monoclinic space group P?!,/a, with a l&757(3), b 15.678(3), c, 12.150(2) A fi 92.83(2)” and Z = 4; R = 0.063 for 2076 reflections. The palladium atom is coordinated to Br, N, C(18), and the centre of the C(15)-C(16) double bond in a distorted square-planar geometry. Introduction Cyclopalladated compounds are valuable intermediates for regioselective organic synthesis. Carbonylation, vinylation, alkylation, and halogenation reactions of these compounds have been much studied [l]. Recently, increasing attention has been paid to the insertion of alkynes into the Pd-C bonds. Insertion of symmetric and asymmetric alkynes into several five- [2,3] and six-membered [4] cyclopalladated complexes with different N-donor ligands, and also into a few S-donor [5] and O-donor [6] derivatives have been reported. Mono-, bis- and tris-insertions of alkynes have been observed, with formation of seven- and nine-membered cyclome- tallated complexes, but usually depalladation occurs and heterocyclic organic mole- cules are formed, some of them closely related to certain natural products. It is accepted that insertion of alkynes into the Pd-C bonds takes place after the alkyne coordination to the metal. Thus cationic species with solvent molecules as ligands react more easily with alkynes. Although several cyclopalladated derivatives of Schiff bases are known, their reactivity with alkynes has been scarcely studied. Pregosin and Albinati [7] observed 0022-328X/89/$03.50 0 1989 Elsevier Sequoia S.A.