The crystal structure of the dimeric complex (C₈H₁₁PdCl)₂

Abstract

The structure of the dimeric complex (CaHnPdCI)2 has been determined by X-ray analysis. The crystals are rhombohedral, space group R3, with a= 27.155, c= 6"669/~, Z= 9 (hexagonal axes). The intensities were collected on a four-circle diffractometer with Mo Ka radiation. The structure was solved by the heavy-atom method and refined by full-matrix least squares to a final R of 0.048 for 731 non-zero reflexions. This complex obtained from cycloocta-l,5-diene is shown to have a tr-allyl structure.

Versatility of Iminophosphoranes and Noninnocent Behavior of the 1,5-Cyclooctadiene Ligand in Palladium(II) Complexes. Synthesis of σ-Allyl Derivatives

“…The disordered cyclooctadienyl ligand is σ-bonded through the carbon atom C(5AB); there is a nonbonded olefinic group [C(6AB)−C(7A) in the congener shown in Figure ] and a bonded olefinic fragment [C(1A)−C(2AB)]. The different Pd−C bond distances are almost identical, within experimental error, to those reported previously for the η 1 -η 2 -cyclooctadienyl ligand in a dinuclear complex 15c…”

“…The other singular fact about 4 and 5 is the generation of the cyclooctadienyl ligand from the coordinated 1,5-cyclooctadiene by deprotonation with an external base . A plausible mechanism for this process is presented in Scheme and could involve the exo nucleophilic attack of the iminophosphorane (through the iminic N atom) on one olefinic CC bond, giving a σ-alkyl intermediate similar to those reported with phosphorus ylides. 4a,b Once the C−N coupling has taken place, this intermediate could undergo intramolecular deprotonation on the methylene adjacent to the attack position, giving the amino−phosphonium unit and the dichloro η 1 -η 2 -cyclooctadienyl Pd(II) derivative.…”

“…While 31 P NMR data clearly show the presence of the aminophosphonium unit in solution, and 1 H NMR data suggest the perseverance of the hydrogen bond, also in solution, 13 C NMR data indicate that the allyl unit on the cyclooctadienyl ligand is η 1 -σ bonded. The clear shielding of the coordinated CC olefinic bond with respect to the free olefin and the appearance of the metalated Pd C H signal in the alkylic region are strong evidence for the η 1 -allyl−η 2 -olefin bonding mode of the cyclooctadienyl ligand …”

“…The reaction of 4 with AgClO 4 (1:1 molar ratio) in MeOH gives the mixture of the amino−phosphonium salt 6 , the known organometallic 7 , and AgCl. All components of this mixture could be isolated in pure form by adequate choice of solvents (see Experimental Section).…”

Synthesis, Solution Dynamics, and Crystal Structures of (2,2‘:6‘,2‘‘-Terpyridine)(η1- and η3-allyl)palladium(II) Complexes

“…The palladium atom lies approximately in the plane defined by N1, N2, N3, and C16, with a deviation of 0.0253(5) Å. The C−C bonds and angles of the allyl fragment are unexceptional when compared with other examples of transition-metal η 1 -allyl complexes described in the literature …”