DI-μ-CHLORODICHLOROBIS(η4-TETRAKIS-p-METHOXYPHENYLCYCLOBUTADIENE)DIPALLADIUM: X-RAY STRUCTURE DETERMINATION, SPECTROSCOPIC PROPERTIES, AND REACTIONS WITH NUCLEOPHILES

Article abstract of DOI:10.1016/S0022-328X(00)85577-1

Reaction of bis-p-methoxyphenylacetylene (An2C2) with Na2 gave <(η⁴-An4C4Pd)2Cl3>0.5 which with HCl gave <(An4C4Pd)2Cl4> (6).The complexes <(An4C4Pd)2Y4> (Y=Br, I, NCS, or NCO) were obtained by metathesis.Reaction of 6 with NaN3 gave the η³-cyclobutenyl complex Na<<(N3)An4C4Pd>(N3)Cl>.With other nucleophiles OR^- (6) gave the dinuclear η³-cyclobutenyl complexes <<(RO)An4C4Pd>2Cl2> (R=H, Me, Et, Prⁱ or COCH3); AgPF6 in the presence of L (MeCN, Bu-tNC, Me2NC, Me2C2 or py) gave <(η⁴-An4C4Pd)2Cl2L2>2 and in the presence of bipy gave <η⁴-An4C4Pd(bipy)Cl>PF6.The X-ray crystal structure of the dinuclear complex 6 showed each Pd to be η⁴-coordinated to a square planar cyclobutadiene, and bound to three chlorines (two bridging and one terminal).The far IR spectra provide a useful guide to the structures of many of these complexes, but 6 is remarkable in that the spectrum between 200 and 300 cm^-1 changes dramatically on grinding.