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

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AbstractThe mononuclear rhodium complexes of cyclodiphosphazane [(cod)RhCl{L‐κP}] (1a) (L = cis‐{(o‐MeOC6H4O)P(μ‐NtBu)}2) and trans‐[Rh(CO)Cl{L‐κP}2] (1b) react in a 1:1 molar ratio with [AuCl(SMe2)] to form the heteronuclear complexes [(cod)RhCl{μ‐L‐κP,κP}AuCl] (2) and trans‐[Rh(CO)Cl{μ‐L‐κP,κP}2(AuCl)2] (7), respectively, in quantitative yield. The reaction between 1a and CuCl afforded a tetranuclear complex [(cod)RhCl{μ‐L‐κP,κP}Cu(μ‐Cl)]2 (3). Under similar reaction conditions 1 reacts with 2 equiv. of CuX (X = Br, I) to produce the heteronuclear complexes [(cod)RhBr{μ‐L‐κP,κP}Cu(μ‐Br)]2 (4) and [((cod)RhI{μ‐L‐κP,κP})2Cu(μ‐X)2Cu] (X ≈ 1:1 mixture of Cl and I disordered over both sites) (5), respectively, in which two molecules of 1a are bridged by the rhombic, disordered, mixed halide [Cu(μ‐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 RhI/PdII complex [(cod)RhCl{μ‐L‐κP,κP}PdCl(η3‐C3H5)] (6) was synthesized by the reaction of 1a with [PdCl(η3‐C3H5)]2 in a 2:1 ratio. Reaction of 1b with CuI leads to the formation of the tetranuclear complex [Rh(CO)I{μ‐L‐κP,κP}2Cu(μ‐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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)