Coordination of the Aryldiazo Ligand to Transition Metals. Structure of Chloro(bis(3-diphenylphosphinopropyl)Phenylphosphine)Phenyldiazorhodium Hexafluorophosphate Methylene Chloride Solvate, [Rh(C₆H₅P((CH₂)₃P(C₆H₅)₂)₂)Cl(N₂C₆H₅)][PF₆]-CH₂Cl₂

The structure of [RhLCl(N₆C₆H₅)] [PF₆] where L = the tridentate phosphine ligand C₆PH₅P((CH₂)₃P(C₆H₅)₂)₂ has been determined from three-dimensional X-ray counter data collected on a single crystal of the CH₂Cl₂ solvate. The material crystallizes in space group Ci'-P₁ of the triclinic system with two formula units of the complex and two solvent molecules in a cell of dimensions a = 12.675 (7) Å, b = 13.254 (7) Å, c = 15.092 (10) Å, α = 94.78 (5)°, β = 99.47 (5)°, γ = 112.40 (8)°, and V = 2282.3 ų. The observed and calculated (Z = 2) densities are 1.50 (1) and 1.507 g/cm³, respectively. The structure has been refined (on F) by a full-matrix least-squares procedure to a conventional agreement index of 0.057 for 4031 observations having Fo² > 3σ(Fo²). The structural results reveal an ionic complex consisting of [RhLCl(N₂Ph)] ⁺ cations (Ph = C₆H₅) and PF₆^- anions. The geometry of the cation is distorted tetragonal pyramidal with a basal plane consisting of the chloro ligand and the three P atoms of the tridentate phosphine. The apical coordination site is occupied by a doubly bent aryldiazo ligand and thus affords the first structural example of the aryldiazo analog of NO^-, N₂Ph^-. The doubly bent geometry suggests formulation of the complex as the oxidative adduct of N₂Ph⁺ to Rh^ILCl yielding [Rh^IIILCl(N₂Ph)]⁺. Distances and angles of interest within the cation are as follows: Rh-P, 2.368 (3), 2.274 (3), 2.352 (3) A; Rh-Cl, 2.403 (2) Å; Rh-N(l) (a to Rh), 1.961 (7) Å; N(1)‒N(2), 1.172 (9) Å; N(2)‒C(7) (Ph), 1.445 (11) Å; Rh-N(l)‒N(2), 125.1 (6)°; N(l)‒N(2)‒C(7), 118.9 (8)°. The structural results are compared with those for the corresponding NO complex, [RhLCl(NO)]⁺, and with the parent complex, RhLCl. The implications of the nitrosyl-aryldiazo analogy are discussed.