REACTIVITY OF PALLADIUM(II) COMPLEXES WITH BIDENTATE BIS(PHOSPHINE) LIGANDS TOWARD THE OCTAHYDROTRIBORATE(1-) ANION AND DEPENDENCE OF THE REACTION UPON HALIDE ARRANGEMENT - MOLECULAR-STRUCTURE OF THE TRANS-(BIS(DIPHENYLPHOSPHINO)HEXANE)PALLADIUM(II) DICHLORIDE DIMER

The reactivity of the palladium(II) bis(phosphine) complexes, (Ph2P(CH2)nPPh2)PdCl2 (n = 1-6), toward the octahydrotriborate(1-) anion, [B3H8]-, has been investigated. For n = 1-4, the metallaborane (Ph2P(CH2)nPPh2)Pd(B3H7) is produced, although the yield depends upon the organic chain length of the phosphino ligand and is maximized when n = 2. Our observation that no reaction occurs between the [B3H8]- anion and (bis(diphenylphosphino)pentane)- or (bis(diphenylphosphino)hexane)- palladium(II) dichloride leads us to examine the structure of these starting materials. Unlike (Ph2P(CH2)nPPh2)PdCl2 for n = 1-4, which are cis monomers, complexes with n = 5 or 6 are dimeric with a trans arrangement of chloro substituents; the molecular structure of trans-[(Ph2P(CH2)6PPh2)PdCl2]2 is presented: triclinic, P-1BAR; a = 9.448 (2), b = 11.772 (2), c = 16.983 (3) angstrom; alpha = 74.18 (2), beta = 87.14 (2), gamma = 77.59 (2)-degrees; V = 1774.9 (9) angstrom-3, Z = 2; R(F) = 5.17%. A detailed comparison of this structure with those of related complexes is made.