Investigation of Monomeric versus Dimericfac-Rhenium(I) Tricarbonyl Systems Containing the Noninnocent 8-Oxyquinolate Ligand

Abstract

Synthesis and characterization of the dimeric [fac-Re(R-OQN)(CO) 3 ] 2 and monomeric fac-Re(R-OQN)-(CO) 3 (CH 3 CN) complexes are reported where R = unsubstituted, 2-methyl, 5,7-dimethyl, or 5-fluoro and OQN = 8oxyquinolate. Facile solvolysis of the dimeric systems is observed in coordinating media quantitatively yielding the monomer complexes in situ. Due to poor synthetic yields of the dimeric precursors, a direct synthetic strategy for isolation of the acetonitrile monomer complexes with an improved yield was developed. The fac-Re(CH 3 CN) 2 (CO) 3 Cl complex was easily generated in situ as a convenient intermediate to give the desired products in quantitative yield via reaction with the appropriately substituted 8-hydroxyquinoline and tetramethylammonium hydroxide base. Key to the success of this reaction is the precipitation of the product with triflic acid, whose conjugate triflate base is here noncoordinating. Furthermore, isolation of the solvated single crystal [fac-Re(FOQN)(CO) 3 ](μ-Cl)[fac-Re(FHOQN)(CO) 3 ]•CH 3 C 6 H 5 has allowed a unique opportunity to access a possible reaction intermediate, giving insight into the formation of the [fac-Re(R-OQN)(CO) 3 ] 2 dimeric systems. Spectroscopic features (UV−vis, FTIR, and 1 H NMR) of both monomeric and dimeric structures are discussed in terms of the π-electron-donating ability of the oxyquinolate ligand. Interpretation of these electronic effects and the associated steric properties is aided by single-crystal X-ray diffraction, electrochemical, and DFT/TD-DFT computational studies.

Twofac-tricarbonylrhenium(I) azadipyrromethene (ADPM) complexes: ligand-substitution effect on crystal structure

“…Consistent with the effect of the difference in charge density on the metal, the Re1-N4(ACN) bond distance in (2) [2.181 (4) Å ] is similar within 3 to those reported for the neutral complexes [Re(ACN)(L)(CO) 3 ] (L is an 8-oxyquinolate-type ligand; Zhao et al, 2013) and [Re(ACN) 2 (trifluoroacetato-O)(CO) 3 ] (Kia & Fun, 2008), while being longer than in the cationic complex [Re(bpy)(ACN)(CO) 3 ] + [bpy is 2,2 0bipyridine; 2.140 (3) Å ; Chen et al, 2003]. The same type of comparison for (3) shows the Re1-O8(DMSO) bond [2.218 (3) Å ] to be longer than in the corresponding cationic complex [Re(bpy)(DMSO)(CO) 3 ] + (Casanova et al, 2006), as expected.…”

Synthesis and Photochemical Properties of Re(I) Tricarbonyl Complexes Bound to Thione and Thiazole-2-ylidene Ligands

“…The reactions were followed focusing on the downfield signal belonging pyridyl H6 atom. acetonitrile at reflux for 24 h. [49] The IR spectra of these complexes matched identically to that of the final species observed in the ligand exchange of both Re(1)(CO)3Cl and Re(1)(CO)3Br (see Figures S18-19). Photochemical studies were conducted on both Re(1)(CO)3Cl and Re(1)(CO)3Br using the same conditions as previously reported for Re-NHC complexes.…”

Synergistic interaction of Re complex and amine functionalized multiple ligands in metal-organic frameworks for conversion of carbon dioxide

“…The presence of -NH 2 groups and ReTC in Re-MOF-NH 2 (X%) was confirmed through IR spectra (Figs 2e and S6 in the Supplementary Information). The peak at 1655 cm −1 was assigned to the N-H bending mode of the -NH 2 functional group, while those at 2022, 1920, and 1910 cm −1 correspond to the C≡O stretching ones of ReTC 9 , 23 . In addition, the UV-vis spectra and XPS results of Re-MOF-NH 2 (X%) support the presence of ReTC, BPDC-(NH 2 ) 2 , and BPDC (Figs S7 and S8 in the Supplementary Information).…”