Cyclodiphosphazane cis{(o-MeOC6H4O)P(mu-NtBu)}2 as a Bridging Bidentate Ligand: Synthesis, Structures of Heterometallic Complexes, and Halogen Exchange Between Rh-Cl and Cu-X (X = Br, I)

摘要

The mononuclear rhodium complexes of cyclodiphosphazane [(cod)RhCl{L-kappa P[] (1a) (L = cis-{(o-MeOC6H4O)P(mu-NtBu))2) and trans-[Rh(CO)Cl{L-kappa P}2] (1b) react in a 1:1 molar ratio with [AuCl(SMe2)] to form the heteronuclear complexes [(cod)RhCl{mu-L-kappa P,kappa P}AuCl] (2) and trans-[Rh(CO)-Cl{mu-L-kappa P,kappa P}2(AuCl)2] (7), respectively, in quantitative yield. The reaction between 1a and CuCl afforded a tetranuclear complex [(cod)RhCl{mu-L-kappa P,kappa P}Cu(mu-Cl)]2 (3). Under similar reaction conditions 1 reacts with 2 equiv. of CuX (X = Br, I) to produce the heteronuclear complexes [(cod)RhBr{mu-L-kappa P, kappa P}Cu(mu-Br)]2 (4) and [((cod)RhI{mu-L-kappa P, kappa P})2Cu(mu-X)2Cu] (X approx= 1:1 mixture of Cl and I disordered over both sites) (5), respectively, in which two molecules of la are bridged by the rhombic, disordered, mixed halide [Cu(mu-X)2Cu] (5: X = Br; 6: X = Cl, I) unit. The crystal structures of 4 and 5 confirm the halogen exchange between the Rh-Cl and CuX (X = Br, I) moieties which leads to the formation of Rh-Br and Rh-I bonds. The heterodinuclear Rh~I/Pd~(II) complex [(cod)RhCl{mu-L-KP,KP}PdCl(eta~3-C3H5)] (6) was synthesized by the reaction of 1a with [PdCl(eta~3-C3H5)]2 in a 2:1 ratio. Reaction of 1b with CuI leads to the formation of the tetranuclear complex [Rh(CO)I{mu-L-kappa P, kappa P}2Cu(mu-I)]2 (8) containing two terminal uncoordinated phosphorus(III) centers irrespective of reactant ratio and reaction conditions. Halogen exchange reaction which leads to the formation of the Rh-I bond was also observed during the preparation of complex 8.