Neutral and cationic ruthenium carbonyl complexes [Ru(CO)(2,2′-dipyridylamine)(PR3)Cl2] and [Ru(CO)(N–N)(PPh3)2(H)]Cl: synthesis, structural characterization and transfer-hydrogenation

Abstract

The neutral complexes [Ru(CO)(dpa)(PR 3 )Cl 2 ] (R = Ph (1) or p-tol (2); dpa = 2,2 0 -dipyridylamine) were synthesized by the reaction of [Ru(CO)(dmf)(PR 3 ) 2 Cl 2 ] (dmf = N,N-dimethylformamide) and the dpa ligand, while the cationic carbonyl hydride complexes [Ru(CO) (N-N)(PPh 3 ) 2 (H)]Cl were synthesized by reaction of [Ru(CO)(PPh 3 ) 3 Cl(H)] and the appropriate N-N ligand [N-N = 2,2 0 -bipyridine = bipy (3), 2,2 0 -4,4 0 dimethylbipyridine = dmb (4) and 2,2 0 -dipyridylamine = dpa (5)]. The complexes were characterized by NMR ( 31 P, 1 H and HMBC 1 H-31 P), FTIR, elemental analysis and X-ray diffraction. The molecular structure of [Ru(CO)(dpa)(PPh 3 ) Cl 2 ] (1) was determined by X-ray crystallography. The crystal packing is stabilized by strong (CH 3 )O-HÁÁÁCl and N-HÁÁÁOH(CH 3 ) hydrogen bonds between symmetry-related molecules leading to the formation of dimers. Complexes 1-6 were evaluated as pre-catalysts for the reduction of acetophenone under transfer-hydrogenation conditions using isopropanol as hydrogen source, and conversions up to 86 % in 4 h were achieved.

Bifunctional RuII‐Complex‐Catalysed Tandem C−C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents

“…All the chemicals were purchased from Sigma–Aldrich, Alfa Aesar, SD Fine and Spectrochem. 6,6′‐dihydroxy‐2,2′‐bipyridine, 6,6′‐dimethoxy‐2,2′‐bipyridine, [RuHCl(CO)(PPh 3 ) 3 ], [RuCl 2 (PPh 3 ) 3 ], [(2,2′‐bipyridine)Ru(H)(CO)(PPh 3 ) 2 ]Cl ( 1 a ) and [(2,2′‐bipyridine)RuCl 2 (PPh 3 ) 2 ] ( 2 a ) were synthesised according to previously reported literature procedures. 1 H, 13 C and 31 P NMR spectra were recorded on Jeol 400 and 500 MHz spectrometer.…”

The Golden Age of Transfer Hydrogenation

“…Not surprisingly, TH involving ruthenium complexes with bi- or polydentate backbones received ever-increasing attention in the past few years. − Numerous variations and modifications of conventional polydentate ligands including PNNP, − NNN, − CNN, − and NNO types, NNP chelating fragments, and PPPC have been extensively investigated with the aim to explore more efficient ruthenium catalysts. Moreover, the tolerance of these conventional ruthenium catalysts to substrate variations, especially for the functional unsaturated compounds, has been investigated with polydentate ligands.…”

Carboxamide carbonyl-ruthenium(ii) complexes: detailed structural and mechanistic studies in the transfer hydrogenation of ketones

“…In comparison to literature reports, the catalytic activities achieved by Ru1-Ru4 fall within the range of other related Ru(II)-PPh 3 complexes of TOF up to 1.0 Â 10 2 h À1 . [49][50][51][52][53][54][55][56][57] However, the catalytic activities of complexes Ru1-Ru4 are lower compared to some of the highly active ruthenium(II) complexes where the TOFs between 1.0 Â 10 4 -1.0 Â 10 5 h À1 were achieved. 58-61 2.3.4 Investigation of TH reactions using different ketone substrates.…”