Facile Oxidative Addition of C−Cl Bonds to New Neutral and Cationic Rhodium(I)-Bipyridine Complexes

Abstract

Neutral and cationic Rh(dmbpy) systems (dmbpy = 4,4Ј-dimethyl-2,2Ј-bipyridine) were synthesized starting from different metal precursors. [RhCl(dmbpy)(DMSO)] (3) was obtained either from the ethylene precursor [RhCl(dmbpy)(C 2 H 4 )] (1) or directly from [Rh 2 Cl 2 (COE) 4 ] (COE = cyclooctene) in DMSO. The neutral isocyanide complex [RhCl(dmbpy){CNC(CH 3 ) 3 }] (4) was obtained by reaction of 1 with tert-butyl isocyanide. Reaction of dmbpy with [Rh(DMSO) 4 ]PF 6 gave the corresponding cationic complex [Rh(dmbpy)(DMSO) 2 ]PF 6 (5), and the cationic system [Rh(dmbpy){CNC(CH 3 ) 3 } 2 ]BF 4 (6) was prepared starting from [Rh(dmbpy)(HD)]BF 4 (2) (HD = 1,5-hexadiene). All of these complexes were found to activate the C−Cl bond in benzyl

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

“…3-Cl can also be generated by photolysis of 2 in methylene chloride at low temperature (eq 4, Figure b). Oxidative addition of the C–Cl bond of dichloromethane − and chloroform to rhodium­(I) has been observed previously. …”

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

“…3-Cl can also be generated by photolysis of 2 in methylene chloride at low temperature (eq 4, Figure b). Oxidative addition of the C–Cl bond of dichloromethane − and chloroform to rhodium­(I) has been observed previously. …”

Rhodium Complexes Containing a Tridentate Bis(8-quinolyl)methylsilyl Ligand: Synthesis and Reactivity

“…However, the Rh−O distance of 4.384(4) Å is too long to represent a bonding interaction. The Rh−C bond distances (2.093(4) and 2.079(4) Å) fall within the expected range for such Rh−C(benzyl) bonds 4 ORTEP diagram of complex 12 with thermal ellipsoids shown at the 50% probability level.…”

Synthesis, Characterization, and Transition-Metal Complexes of 3,4-Diazaphospholanes

“…For complexes 29 and 27 , treatment with hydrogen gas accelerated the chloride abstraction (Scheme ). Activation of chlorinated solvents by Rh(I) complexes is not unprecedented, − but most examples yield the product of oxidative addition. − ,− Generally, oxidative addition of CH 2 X 2 (X = Cl, Br, I) to Rh(I) is enhanced by electron-donating ligands, but as our data have established (vide supra), the 3,4-diazaphospholanes are electron deficient, which argues against an oxidative addition pathway. Less abundant are examples of methylene chloride activations that only add chlorides to the rhodium, − and to the best of our knowledge, there are no examples of chloride abstractions without a change in formal oxidation state.…”

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

“…3-Cl can also be generated by photolysis of 2 in methylene chloride at low temperature (eq 4, Figure b). Oxidative addition of the C–Cl bond of dichloromethane − and chloroform to rhodium­(I) has been observed previously. …”

Rhodium Complexes Containing a Tridentate Bis(8-quinolyl)methylsilyl Ligand: Synthesis and Reactivity

“…However, the Rh−O distance of 4.384(4) Å is too long to represent a bonding interaction. The Rh−C bond distances (2.093(4) and 2.079(4) Å) fall within the expected range for such Rh−C(benzyl) bonds 4 ORTEP diagram of complex 12 with thermal ellipsoids shown at the 50% probability level.…”

Synthesis, Characterization, and Transition-Metal Complexes of 3,4-Diazaphospholanes

“…For complexes 29 and 27 , treatment with hydrogen gas accelerated the chloride abstraction (Scheme ). Activation of chlorinated solvents by Rh(I) complexes is not unprecedented, − but most examples yield the product of oxidative addition. − ,− Generally, oxidative addition of CH 2 X 2 (X = Cl, Br, I) to Rh(I) is enhanced by electron-donating ligands, but as our data have established (vide supra), the 3,4-diazaphospholanes are electron deficient, which argues against an oxidative addition pathway. Less abundant are examples of methylene chloride activations that only add chlorides to the rhodium, − and to the best of our knowledge, there are no examples of chloride abstractions without a change in formal oxidation state.…”

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

“…3-Cl can also be generated by photolysis of 2 in methylene chloride at low temperature (eq 4, Figure b). Oxidative addition of the C–Cl bond of dichloromethane − and chloroform to rhodium­(I) has been observed previously. …”

Rhodium Complexes Containing a Tridentate Bis(8-quinolyl)methylsilyl Ligand: Synthesis and Reactivity

“…However, the Rh−O distance of 4.384(4) Å is too long to represent a bonding interaction. The Rh−C bond distances (2.093(4) and 2.079(4) Å) fall within the expected range for such Rh−C(benzyl) bonds 4 ORTEP diagram of complex 12 with thermal ellipsoids shown at the 50% probability level.…”

Synthesis, Characterization, and Transition-Metal Complexes of 3,4-Diazaphospholanes

“…For complexes 29 and 27 , treatment with hydrogen gas accelerated the chloride abstraction (Scheme ). Activation of chlorinated solvents by Rh(I) complexes is not unprecedented, − but most examples yield the product of oxidative addition. − ,− Generally, oxidative addition of CH 2 X 2 (X = Cl, Br, I) to Rh(I) is enhanced by electron-donating ligands, but as our data have established (vide supra), the 3,4-diazaphospholanes are electron deficient, which argues against an oxidative addition pathway. Less abundant are examples of methylene chloride activations that only add chlorides to the rhodium, − and to the best of our knowledge, there are no examples of chloride abstractions without a change in formal oxidation state.…”