Solvent-Dependent Hemilability of (2-Diphenylphosphino)Phenol in a Ru(II) para-Cymene System

Abstract

The addition of Ph2P­(2-C6H4OH) to [(η6-p-cymene)­RuCl­(μ-Cl)]2 led to the formation of three distinct products, depending on the experimental conditions. The previously reported [(η6-p-cymene)­RuCl­{κ2 P,O-PPh2(2-C6H4O)}], 1, was obtained in 90% yield using MeOH as the solvent, in the presence of a base (Et3N). Conversely, [(η6-p-cymene)­RuCl­{κ2 P,O-PPh2(2-C6H4OH)}]­Cl, [2]­Cl, was afforded (88% yield) in MeOH without using the base. However, [(η6-p-cymene)­RuCl2{κP-PPh2(2-C6H4OH)}], 3, was the major species in chlorinated solvents. Compounds 1, [2]­Cl, and 3 were characterized by analytical and spectroscopic (IR, NMR) methods. The X-ray structures of [2]+ and 3 were determined, with the latter forming hydrogen bond dimeric units in the solid state. The dissolution of [2]Cl into a series of deuterated solvents, except methanol, led to rapid equilibration between [2]Cl and 3, revealing the hemilabile behavior of the phosphino-phenol ligand. According to Pulsed-Field Gradient Spin Echo (PGSE)-NMR and DFT studies, the dimeric nature of 3 persists in solution; thus, the hydrogen-bonding properties of MeOH are crucial to stabilize [2]Cl with respect to 3, with the latter being 3.4 kcal mol–1 more stable than the former in the gas phase. Compound 1 underwent electrophilic additions by HCl, HBF4, and MeCOCl to give, respectively, [2]Cl (the reverse process being viable with Et3N), [2]­BF4, and the ester [(η6-p-cymene)­RuCl2{κP-PPh2(2-C6H4OCOMe)}], 5. The reaction of 1 with AgNO3 afforded the nitrate complex [(η6-p-cymene)­Ru­(NO3)­{κ2 P,O-PPh2(2-C6H4O)}], 4. Compounds [2]­BF4, 4, and 5 were isolated in the solid state in good to high yields and characterized by elemental analysis and IR and NMR spectroscopy.

Observing the three-dimensional dynamics of supported metal complexes

“…Dynamics have been shown to influence not only enzyme chemistry but also homogeneous catalysis where structural flexibility has been linked to enhanced activity. [22][23][24][25][26][27][28][29][30] Similar arguments have also been made in the case of single-site heterogeneous catalysts. 31 In supported metal catalysis, the rapid dynamics of metal clusters has also been shown to generate short-lived highlyactive species that are thought to dominate catalysis.…”

Frustrated and Realized Hydrogen Bonding in 4-Hydroxy-3,5-ditertbutylphenylphosphine Derivatives

“…Phenolic phosphines such as Ph 2 PC 6 H 4 OH have been used either natively or with chain extenders such as triethylene glycol to enhance solubility for a ruthenium complex for catalysis in water . The confinement of triarylphosphines in microenvironments leading to enhanced performance of catalytic processes as well as a number of studies aimed at enhanced anticancer activity also of ruthenium complexes − have been reported.…”

“…12 1 + X, +Y, +Z; 13 X, Y, 1 + Z. Notes: Calculated by Mercury CSD (using Bondi van der Waals radii).…”

Synthesis and Characterisation of Transition Metal Complexes of a Novel 1,5‐benzodiazepine‐Functionalised Tertiary Phosphine

“…[22] Furthermore, bridge cleavage reactions of metal dimers with P/N-chelating ligands in CH 3 OH have been shown to afford analogous P/N-chelate complexes. [23,24] On this basis we tentatively suggest formation of intermediate B whereby 1 coordinates through both P/N amine donor centres. This is supported by our observation that 1 can behave similarly, as found in [Pt(CH 3 )Cl(P,N-1)] 4, which is readily accessible from [Pt(CH 3 )Cl(η 4 -cod)] and 1.…”