Stereoselective formation and catalytic activity of hydrido(acylphosphane)(chlorido)(pyrazole)rhodium(III) complexes. Experimental and DFT studies

摘要: The reaction of [{RhCl(COD)}2] (COD = 1,5-cyclooctadiene) with L pyrazole (Hpz), 3(5)-methylpyrazole (Hmpz) or 3,5-dimethylpyrazole (Hdmpz) and PPh2(o-C6H4CHO) (Rh : L : P 1 : 2 : 1) gives hydridoacyl complexes [RhHCl{PPh2(o-C6H4CO)}(L)2] (1). Stereoselective formation 1-Hpz 1-Hmpz pyrazoles trans to hydrido phosphorus hydrogen bond O-acyl chlorido occur. is a mixture two linkage isomers in 9 : 1 ratio, 5-methylpyrazole ligands one 3- ligand, respectively. Fluxional 1-Hdmpz undergoes metallotropic tautomerization equal amounts 1a-Hdmpz 1b-Hdmpz, chlorido, Complexes 1 readily exchange by afford [RhCl2{PPh2(o-C6H4CO)}(L)2] (2-Hpz, 2-Hmpz 2-Hdmpz) as single cis chloridos N–H⋯Cl bonds. PPh3 PPh2OH affords static [RhHCl{PPh2(o-C6H4CO)}(PPh3)L] (3) [RhHCl{PPh2(o-C6H4CO)}(PPh2OH)L] (4) respectively P-atoms forming 3-Hpz 3-Hmpz contain species while 3-Hdmpz 3a-Hdmpz 3b-Hdmpz. 4, an additional O–H⋯O bond, selectively only the cis-H,Cl all three ligands. 1 : 1 : 2) led P-atoms, [RhHCl{PPh2(o-C6H4CO)}{PPh2(o-C6H4CHO)-κP}L] (5-Hpz, 5a-Hdmpz 5b-Hdmpz), at room temperature, [RhCl{PPh2(o-C6H4CO)}{PPh2(o-C6H4CHOH)}(Hmpz)] (6-Hmpz) [RhCl{PPh2(o-C6H4CO)}2L] (7) evolution refluxing benzene. DFT calculations were used predict correct isomers, their ratios particular intramolecular bonds these complexes. Single crystal X-ray diffraction analysis was performed on 2-Hpz, 7-Hpz. are efficient homogeneous catalysts (0.5 mol% loading) hydrolysis amine– ammonia–borane (AB) generate up 3 equivalents presence air.