A Rationale for the Linear Correlation of Aryl Substituent Effects in Iron(0) Tricarbonyl Complexes Containing α,β-Unsaturated Enone (Chalcone) Ligands

Abstract

A library of iron(0) tricarbonyl complexes containing η4-bound α,β-unsaturated enone ligands [Fe(CO)3(η4-RCHCH−C{Ph}O)] has been prepared to facilitate comprehensive correlation of the electronic withdrawing/donating properties of the substituent, R, with the strength of the metal−ligand interaction. The IR and NMR spectroscopic data proved invaluable in aiding a comprehensive correlation and global understanding of the aryl substituent effects. The frequency of the M−CO bands in the infrared spectra of these species exhibits a linear correlation with the Hammett parameters for the substituents. The coordination shifts in both the 1H and 13C NMR spectra for the ligands exhibit a similar linear relationship. The largest coordination shifts are observed when more electron-withdrawing groups are present, implying that the organic ligand is primarily acting as a π-acid. The structures of six complexes of this type have been determined by single-crystal X-ray diffraction.

π-Acidic alkene ligand effects in Pd-catalysed cross-coupling processes: exploiting the interaction of dibenzylidene acetone (dba) and related ligands with Pd(0) and Pd(ii)

“…An excellent correlation is also seen between the rates and the calculated C=C charge in the dba-4,4¢-Z ligands. 33 Furthermore, related chalcone (p-Z-C 6 H 4 CH=CHPh) ligands show similar electronic effects at Fe • , 38 demonstrating that such ligands 39 could be used in the future to influence steps in classical cross-coupling processes.…”

Modification of the deoxy-myoglobin/carbonmonoxy-myoglobin UV-vis assay for reliable determination of CO-release rates from organometallic carbonyl complexes

“…One needs to factor in CO-RM absorbance to calculate accurate CO release rates and CO quantification. Tricarbonyl(h 4 -chalcone)iron(0) complex 1 13 is an exemplar CO-RM, where processing by Method A (vide supra) provided unsatisfactory results.…”

“…Fig 13. Difference spectra showing the disparity between the calculated spectra and the standard spectra vs. wavelength for 1.…”

17 e−rhenium dicarbonyl CO-releasing molecules on a cobalamin scaffold for biological application

“…Transition metal carbonyl complexes have been predominantly evaluated as CORMs. There are numerous examples available in the literature, [13][14][15][16][17][18][19][20][21][22][23][24][25] of which three molecules have been most extensively investigated in biology and medicine: the lipid-soluble tricarbonyldichlororuthenium(II) dimer ([Ru(CO) 3 Cl 2 ] 2 , CO-RM2), [26][27][28] the water soluble tricarbonylglycinatoruthenium(II) monomer ([Ru(CO) 3 Cl(glycinato)], CO-RM3) [29][30][31][32][33][34] and the boron-containing carboxylic acid Na 2 [H 3 BCO 2 ] salt (CO-RMA1). [35][36][37][38] Treatment of several diseases with these CORMs has shown that the molecules elicit the same type of therapeutic effects as CO gas.…”