Ru-η6-benzene-phosphine complex-catalyzed transfer hydrogenation of ketones

Dichlorido(η6-p-cymene)[tris(4-methoxyphenyl)phosphane]ruthenium(II)

The title compound, [RuCl₂(C₁₀H₁₄)(C₂₁H₂₁O₃P)] crystallizes with two independent complex mol­ecules in the asymmetric unit. In the crystal, weak C—H⋯Cl/O/π inter­actions are observed.

The title compound, [RuCl₂(C₁₀H₁₄)(C₂₁H₂₁O₃P)], crystallizes with two complex mol­ecules in the asymmetric unit. The Ru^II atom has a classical three-legged piano-stool environment being coordinated by a cymene ligand [Ru—centroid = 1.707 (2)/1.704 (2) Å], a tris­(4-meth­oxy­phen­yl)phosphane ligand [Ru—P = 2.3629 (15)/2.3665 (15) Å] and two chloride atoms with the Ru—Cl bonds adopting two distinct values of 2.4068 (16)/2.4167 (16) and 2.4016 (15)/2.4244 (16) Å. The effective cone and solid angles for the phosphane ligands were calculated to be 149.5/150.2° and 25.3/25.6°, respectively. In the crystal, weak C—H⋯Cl/O/π inter­actions are observed. The crystal was refined as a two-component twin.

Transfer Hydrogenation from 2-propanol to Acetophenone Catalyzed by [RuCl2(η6-arene)P] (P = monophosphine) and [Rh(PP)2]X (PP = diphosphine, X = Cl−, BF4−) Complexes

The reduction of ketones through homogeneous transfer hydrogenation catalyzed by transition metals is one of the most important routes for obtaining alcohols from carbonyl compounds. The interest of this method increases when opportune catalytic precursors are able to perform the transformation in an asymmetric fashion, generating enantiomerically enriched chiral alcohols. This reaction has been extensively studied in terms of catalysts and variety of substrates. A large amount of information about the possible mechanisms is available nowadays, which has been of high importance for the development of systems with excellent outcomes in terms of conversion, enantioselectivity and Turn Over Frequency. On the other side, many mechanistic aspects are still unclear, especially for those catalytic precursors which have shown only moderate performances in transfer hydeogenation. This is the case of neutral [RuCl2(η6-arene)(P)] and cationic [Rh(PP)2]X (X = anion; P and PP = mono- and bidentate phosphine, respectively) complexes. Herein, a summary of the known information about the Transfer Hydrogenation catalyzed by these complexes is provided with a continuous focus on the more relevant mechanistic features.

Optically active P5-deltacyclenes: selective oxidation, ligand properties, and a diastereoselective rearrangement reaction

Cage-chiral tetra-tert-butyl-P5-deltacyclene is accessible as a pair of highly enriched enantiomers and . The only secondary phosphorus atom P1 of the cage can be selectively oxidized by reaction with t-BuOOH. The P1-oxo species and , allow the direct determination of their ee values. Oxidation occurs with the complete retention of the optical activity of the compounds. The chiroptical properties of and are strongly dominated by their cage chirality, the oxygen atom does not contribute significantly. Elemental sulfur and selenium oxidize P5 with high preference to yield P5-thio- and P5-seleno-P5-deltacyclenes and of the intact cages again. Longer reaction time and more than stoichiometric amounts of selenium, leads to tri-seleno-P5-tetracycloundecane , a partially opened oxidized rearrangement product. The ligand properties of racemic were determined. Diphosphetane phosphorus atom P2 of is the active donor center to bind a Cr(CO)5 fragment, but a tautomerization of takes place if [(benzene)RuCl2]2 is added. A hydrogen atom migrates from P1 to the oxygen atom to form a phosphinous acid ligand. The lone pair of P1 is regenerated and acts as the active ligand function of the cage in this case. As for , the base n-BuLi induces an efficient cage rearrangement reaction of , where P1 and the neighboring carbon atom C4 containing its t-Bu substituent change places. C4 moves to its new position without breaking the bond with P5, this way forming the novel P1-oxo-P5-norsnoutene cage in a highly diastereoselective process.

Ruthenium complexes of P-stereogenic phosphines with a heterocyclic substituent

Optically pure P-stereogenic monophosphorus ligands containing a heterocyclic substituent have been prepared. They have been coordinated to Ru-η⁶-arene moieties in which the ligands act as mono- or bidentate. The complexes catalyse asymmetric transfer hydrogenation reactions with up to 70% ee.

Half-sandwich Ru(η6-C6H6) complexes with chiral aroylthioureas for enhanced asymmetric transfer hydrogenation of ketones – experimental and theoretical studies

The efficiency of Ru–benzene complexes towards ATH of ketones was studied.

(η(6)-Benzene)-dichlorido(dicyclo-hexyl-phenyl-phosphane)ruthenium(II) benzene sesquisolvate

The asymmetric unit of the title compound, [RuCl2(C6H6)(C18H27P)]·1.5C6H6, contains one mol-ecule of the Ru(II) complex and one and a half solvent molecules as one of these is located about a centre of inversion. The Ru(II) atom has a classical three-legged piano-stool environment being coordinated by an η(6)-benzene ligand [Ru-centroid = 1.6964 (6) Å], two chloride ligands with an average Ru-Cl bond length of 2.4138 (3) Å and a dicyclo-hexyl-phenyl-phosphane ligand [Ru-P = 2.3786 (3) Å]. The effective cone angle for the phosphane was calculated to be 158°. In the crystal, weak C-H⋯Cl hydrogen bonds link the Ru(II) complexes into centrosymmetric dimers. The crystal packing exhibits intra- and inter-molecular C-H⋯π inter-actions resulting in a zigzag pattern in the [101] direction.

(η(6)-Benzene)-(benzyl-diphenyl-phos-phane)dichloridoruthenium(II)

In the title compound, [RuCl₂(C₆H₆)(C₁₉H₁₇P)], the Ru^II atom has a distorted pseudo-octa­hedral coordination environment with the metrical parameters around the metallic core as Ru—centroid(η⁶-benzene) = 1.6894 (11) Å, Ru—P = 2.3466 (6), Ru—Cl(avg.) = 2.4127 (7) Å; Cl—Ru—Cl = 88.07 (2) and Cl—Ru—P = 82.77 (2), 87.65 (2)°. The effective cone angle for the benzyl­diphenyl­phosphane was calculated to be 143°. In the crystal C—H⋯Cl and C—H⋯π inter­actions are observed.