Crown-shaped tetrametallic imidoyl complexes of palladium. X-Ray crystal structure of [{[Pd₂{µ-C(C₆F₅)NMe}₂](µ-Cl)(µ-MeCO₂)}₂]

The complexes [{[Pd2{µ-C(C6F5)NR1}2](µ-X1)(µ-X2)}n](R1= Me or p-tolyl; X1= X2= Cl) and their derivatives (X1= Cl, X2= MeCO2 or CF3CO2; X1= X2= MeCO2 or CF3CO2), obtained by metathetical reactions with the corresponding silver salts, are shown to be tetrametallic (n= 2) by molecularweight determinations. Their structures are discussed on the basis of 1H and 19F n.m.r. data. The crystal structure of the title complex has been solved by X-ray diffraction methods [space group P21/n, a= 14.380(4), b= 19.980(4), c= 15.976(4)Å, β= 103.51(3)°, Z= 4, R′= 0.046 for 5 428 unique observed reflections]. The tetrametallic molecule is crown-shaped. The bond lengths at palladium reflect the strong trans influence of the imidoyl-C atom; the Pd–Cl bonds trans to C are amongst the longest known.