Addition of arenediazonium ligands to a PdPd bond: a reinvestigation

Arenediazonium salts [p-YC6H4N2][BF4] (YH, CH3, OCH3, F, NO2) react with the A-frame precursor complexes [Pd2X2(dppm)2] (1) (XCl, Br, I; dppmbis(diphenylphosphino)methane) affording 1:1 adducts.1H and31P NMR spectroscopic data support the formulation of the new complexes as A-frame molecules [Pd2X2(dppm)2(μ-N2-p-C6H4Y)][BF4] (2) containing a symmetrically bridging arenediazenido ligand. The crystal structures of [Pd2I2(dppm)2(μ-N2-p-C6H4CH3)][BF4] (2d) and [Pd2Cl2(dppm)2(μ-N2-p-C6H4F)][BF4] (2f) have been determined by X-ray crystallography. 2d crystallizes in the orthorhombic space group P212121with Z=4 in a unit cell of dimensions a=14.642(4), b=19.166(5), c=21.338(6) Å. The structure was refined to R=0.068 and Rw=0.073 on the basis of 4325 observed reflections with I>3σ(I). 2f crystallizes in the tetragonal space group P43212 with a=14.886(1), c=25.303(8) Å and Z=4. The structure was refined to R=0.039 and Rw=0.043 using 4681 unique reflections and 353 parameters. The formation of [PtPdCl2(dppm)2(μ-N2-p-C6H4F)][BF4] (4) and its solution structure is also described. © 1993.