Intermediates in the time-resolved and matrix photochemistry of (.eta.5-cyclopentadienyl)rhodium complexes. Roles of alkane activation and rhodium-rhodium bond formation

• Published in: Journal of the American Chemical Society Vol. 111; no. 22; pp. 8373 - 8382
• Main Authors: Belt, Simon T, Grevels, Friedrich Wilhelm, Klotzbuecher, Werner E, McCamley, Andrew, Perutz, Robin N
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.10.1989
• Subjects: 400200 - Inorganic, Organic, & Physical Chemistry; 400500 - Photochemistry; BONDING; CALCULATION METHODS; CHEMICAL ACTIVATION; CHEMICAL REACTIONS; CHEMISTRY; COMPLEXES; DATA; DATA ANALYSIS; DECOMPOSITION; Exact sciences and technology; EXPERIMENTAL DATA; FABRICATION; General and physical chemistry; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; JOINING; MEASURING INSTRUMENTS; MEASURING METHODS; NUMERICAL DATA; PHOTOCHEMICAL REACTIONS; PHOTOCHEMISTRY; PHOTOLYSIS; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); REACTION INTERMEDIATES; RHODIUM COMPLEXES; TRANSITION ELEMENT COMPLEXES; Matrix isolation; Rhodium Carbonyl Complexes; Ultraviolet radiation; Laser beam; Metal metal bond; Dinuclear complex; Hapto complex; Transition metal Carbonyl Complexes; Platinoid Complexes; Kinetics; Pulse photolysis
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00204a008

Pulsed laser photolysis studies of solutions of Cp{sub 2}Rh{sub 2}(CO){sub 3}, CpRh(CO){sub 2}, and CpRh(C{sub 2}H{sub 4})CO (Cp = {eta}{sup 5}-C{sub 5}H{sub 5}) are reported using UV/vis and IR detection. Isotopic labeling and polarized photolysis demonstrates that the Rh{sub 2}(CO){sub 2} unit is planar with CO bridges perpendicular to the RhRh axis. Metal-metal bond fission of Cp{sub 2}Rh{sub 2}(CO){sub 3} is observed only in CO-doped matrices. The major photoproduct of Cp{sub 2}Rh{sub 2}(CO){sub 3} in solution is (CpRh({mu}-CO)){sub 2}, which reacts with CO to re-form starting material. The first observable product of photolysis of CpRh(CO){sub 2} in cyclohexane at room temperature is CpRh(CO)(C{sub 6}H{sub 11})H, formed by insertion of CpRhCO into the solvent C-H bonds within 400 ns. The IR experiments show that photolysis of CpRh(C{sub 2}H{sub 4})CO gives a higher yield of CpRh(CO)(C{sub 6}H{sub 11})H than that from CpRh(CO){sub 2}.