The Rh(III) and Ir(III) pentamethylcyclopentadienyl compounds [M(Cp*)(κ2-Ph2Bp)Cl] (M = Rh, 1; M = Ir, 4) were readily prepared from interaction of the salt K[Ph2Bp] (Ph2Bp = diphenylbis(pyrazolyl)borate) and the [M(Cp*)Cl2]2 dimer precursors in dichloromethane under anhydrous conditions. When the same reactions were carried out in non-anhydrous conditions by using acetonitrile as solvent, we observed, in the case of Rh, both B–N bond hydrolysis and Rh–C(Ph) bond activation with the formation of the hydroxy(pyrazolyl)borate complex [Rh(Cp*)(Ph){κ2-(pz)(OH)BPh2}] (2). In contrast, in the case of Ir only B–N hydrolysis was observed and the ionic species [Ir(Cp*)(Hpz){κ2-(pz)(OH)BPh2}]Cl (5) was obtained, upon coordination of the liberated Hpz. Additionally, by reaction of 1 with AgClO4 in acetonitrile, the ionic [Rh(Cp*)(Ph){κ2-(pz)(OH)B(OH)}]ClO4 (3) was isolated. Complexes 1–3 and 5 have been structurally characterized by X-ray crystallography. Spectral studies have been performed for all species, together with a computational DFT modeling investigation. A decomposition mechanism for the diphenylbis(pyrazolyl)borate ligand in the different complexes is proposed.
Boron functionalization and unusual B-C bond activation in rhodium(III) and iridium(III) complexes with diphenylbis(pyrazolylborate) ligands (Ph2Bp)
PETTINARI, RICCARDO;PETTINARI, CLAUDIO;MARCHETTI, FABIO;Mosconi, Edoardo;De Angelis, Filippo
2013
Abstract
The Rh(III) and Ir(III) pentamethylcyclopentadienyl compounds [M(Cp*)(κ2-Ph2Bp)Cl] (M = Rh, 1; M = Ir, 4) were readily prepared from interaction of the salt K[Ph2Bp] (Ph2Bp = diphenylbis(pyrazolyl)borate) and the [M(Cp*)Cl2]2 dimer precursors in dichloromethane under anhydrous conditions. When the same reactions were carried out in non-anhydrous conditions by using acetonitrile as solvent, we observed, in the case of Rh, both B–N bond hydrolysis and Rh–C(Ph) bond activation with the formation of the hydroxy(pyrazolyl)borate complex [Rh(Cp*)(Ph){κ2-(pz)(OH)BPh2}] (2). In contrast, in the case of Ir only B–N hydrolysis was observed and the ionic species [Ir(Cp*)(Hpz){κ2-(pz)(OH)BPh2}]Cl (5) was obtained, upon coordination of the liberated Hpz. Additionally, by reaction of 1 with AgClO4 in acetonitrile, the ionic [Rh(Cp*)(Ph){κ2-(pz)(OH)B(OH)}]ClO4 (3) was isolated. Complexes 1–3 and 5 have been structurally characterized by X-ray crystallography. Spectral studies have been performed for all species, together with a computational DFT modeling investigation. A decomposition mechanism for the diphenylbis(pyrazolyl)borate ligand in the different complexes is proposed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
