Kinetics of Substitution of Weakly Coordinating Nitrate by Chloride in (η⁵-Cp)Ru(CO)(ER₃)ONO₂ (ER₃ = AsPh₃, PPh₃, P(p-anisyl)₃, PPh₂(o-anisyl), P(OPh)₃) in Dichloromethane

Abstract

The d 6 complexes of formula (η 5 -Cp)Ru(CO)(ER 3 )ONO 2 , where ER 3 ) AsPh 3 , PPh 3 , P(panisyl) 3 , PPh 2 (o-anisyl), and P(OPh) 3 , were prepared by reaction of their chloro analogues with AgNO 3 in CH 2 Cl 2 . They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH 2 Cl 2 in the presence of excess [N(PPh 3 ) 2 + ]Cl -. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh) 3 < PPh 3 < P(p-anisyl) 3 < AsPh 3 , PPh 2 (oanisyl), with k 1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10 -5 s -1 . Activation parameters for conversion of (η 5 -Cp)Ru(CO)(AsPh 3 )ONO 2 to its chloride are ∆H ‡ ) 17(2) kcal/mol and ∆S ‡ ) -21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20-30% without changing the form of the rate law. The complex containing PPh 2 (o-anisyl) was approximately 2 orders of magnitude more reactive (k 1 ) 4.9 × 10 -3 s -1 ). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing ratelimiting conversion of the neutral nitrato complex into a coordinatively unsaturated ionpaired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh 3 nitrato and chloro complexes and for the PPh 3 chloro complex.

Synthesis, structural characterization, electrochemistry and catalytic transfer hydrogenation of ruthenium(II) carbonyl complexes containing tridentate benzoylhydrazone ligands

“…All the complexes display a strong band in the region 1942e1949 cm À1 which is attributed due to the terminally coordinated carbonyl group and is observed at slightly higher frequency than in the precursor complexes. In addition, other characteristic bands due to ruthenium bound PPh 3 /AsPh 3 in the region 1436e1447 cm À1 are also present in the spectra of all the complexes [36]. The IR spectra of all the complexes therefore confirms the coordination mode of the benzoylhydrazone ligand to ruthenium(II) ion via the phenolate oxygen, the azomethine nitrogen and the imidolate oxygen and indicates the presence of PPh 3 /AsPh 3 groups.…”

Synthesis and Systematic Structural Analysis of Cationic Half‐Sandwich Ruthenium Chalcogenocarbonyl Complexes

“…1 H (400 MHz) and 77 Se{ 1 H} NMR (76 MHz) spectra were recorded on a JEOL ECZ 400 spectrometer at ambient temperature. 13 C{ 1 H} NMR (126 MHz) spectra were recorded on aJ EOL JNM-ECA500 spectrometer at ambient temperature. 125 Te { 1 H} NMR spectra were recorded on aJ EOL JNM-ECS300 spectrometer at ambient temperature.…”

“…125 Te { 1 H} NMR spectra were recorded on aJ EOL JNM-ECS300 spectrometer at ambient temperature. Chemical shifts d are reported in ppm and are referenced to the residual 1 Ha nd 13 Cs ignals of CDCl 3 as the internal standard ( 1 HNMR: d = 7.24; 13 CNMR: d = 77.0 ppm) or to the 77 Se signal of PhSeSePh (d = 459.0 relative to MeSeMe at d = 0ppm) [28] and to the 125 Te signal of PhTeTePh (d = 422.0 relative to MeTeMe at d = 0ppm) [29] as external standards. IR spectra were recorded on a JASCO FT/IR-4600 spectrometer with ad iamond-attenuated total reflectance (ATR) unit.…”

“…The molecular structures of 2-CE were successfully determined by single-crystal X-ray diffraction analyses ( (8) ) [13] and [Cp*Ru(CS)(PPh 2 CH 2 C 4 H 7 O 2 ) 2 ][BPh 4 ]( Cp* = h 5 -C 5 Me 5 À ;R u ÀCS: 1.832(4);C ÀS: 1.554(4) ). [14] For 2-CSe,t he Ru1ÀC1 bond [1.827(4) ]i sl onger than that of half-sandwich complex [Cr(h 6 -C 6 H 5 CO 2 Me)(CO) 2 (CSe)] (1.786(11) ), [15] whereas the C1À Se1 bond (1.693(4) )i ss horter than that of the chromium CSe complex [1.728(10) ].…”

Fluoroarylphosphines as ligands

“…For example, multinuclear NMR spectroscopic studies revealed that [(h 5 -C 5 H 5 )Ru(CO){PPh 2 (C 6 H 4 X-2)}] + (X = Cl, Br), formed by silver(I)-mediated chloride abstraction from [(h 5 -C 5 H 5 )RuCl(CO){PPh 2 (C 6 H 4 X-2)}], possessed an intramolecular RuÁ Á ÁX interaction, whereas no RuÁ Á ÁF interaction was observed on chloride abstraction from [(h 5 - [124]. These observations were supported by calculations that revealed that there is no stabilization gained by a RuÁ Á ÁF interaction in the cation [(h 5 -C 5 H 5 )Ru(CO){PPh 2 (C 6 H 4 F-2)}] + , although considerable stabilization arose for the chloride and bromide analogues [125]. Similarly IrÁ Á ÁCl and IrÁ Á ÁBr interactions, but not an IrÁ Á ÁF interaction, are found in [(COD)Ir{PPh 2 (C 6 H 4 X-2)}] + (COD = h 2 ,h 02 -cycloocta-1,5-diene) [126].…”