Arene-polyfluoroarene π-π stacking between N-heterocyclic carbene ligands of pentamethylcyclopentadienyl group 9 metal complexes

Abstract

Highlights  The crystal structures of the dichloromethane solvates of ( 5pentamethylcyclopentadienyl)rhodium(κC-1-(4-trifluoromethyl-2,3,5,6-the phenyl and trifluoromethyltetrafluorophenyl rings of molecules in a direction perpendicular to the columns and hydrogen bonding between the complex molecules. In contrast those of 1a and 1b display intermolecular lone pair- interactions in the same direction as the hydrogen bonding between the complex molecules. DFT calculations reveal that the - stacking and lone pair- interactions are of approximately the same energy. The difference in the structures arises from the steric requirements of the trifluoromethyl group.

Applications of Transition Metal-Catalyzed ortho-Fluorine-Directed C–H Functionalization of (Poly)fluoroarenes in Organic Synthesis

“…In addition, transition-metal ligated fluorinated benzene compounds have also shown promise as antiproliferative agents against HT29 (colon carcinoma) and MCF-7 (breast adenocarcinoma) . Fluorine-containing organic compounds have also shown tremendous potential in other areas of science and industry such as in agrochemicals (Figure b), − organic light emitting diodes (OLEDs) (Figure c), − electron-transport materials, , crystal engineering, − metal–organic frameworks (MOFs), supramolecular chemistry, semiconducting materials (Figure d), ,, and organic-field-effect transistors (OFETs) (Figure e) . As such, there is a growing demand for the development of novel synthetic methodologies for the generation of these valuable compounds. , In the examples in Figure a,b,e, positions 2 and 6 on the aromatic ring (the ortho positions) are occupied by fluorine.…”

(η5-Pentamethylcyclopentadienyl)iridium{1,3-bis(2,3,4,5,6-pentafluorobenzyl)imidazolin-2-ylidene}dichloride

“…Importantly, these complexes possess catalytic properties [1,2], including for base-free dynamic resolution in combination with an enzyme [3], and display unusual reactivity [4][5][6][7], including carbonfluorine bond activation [8,9]. The structures of some of the complexes have been determined in single-crystal X-ray diffraction studies [5][6][7][8][9][10][11][12][13], but of these, most complexes contain a monofluorinated substituent, and only four bear a perfluorinated aryl substituent. The crystal structure of the dichloromethane solvate of the complex Cp*IrCl 2 {κC-C 6 H 5 CH 2 NC 3 H 2 NCH 2 C 6 F 5 } (1) (Figure 1) [13] display a number of short intermolecular distances that suggest significant attractive interactions: π-π stacking between the phenyl ring of molecule of 1 and the pentafluorophenyl ring of another, hydrogen bonding between the hydrogen atoms of the imidazolin-2-ylidene ring of one molecule of 1 and the chloride ligands of another, hydrogen bonding between the hydrogen atoms of a dichloromethane molecule and the chloride ligands, and an interaction between one of the chlorine atoms of dichloromethane and the C 5 ring of the pentamthylcyclopentadienyl ligand of 1.…”

Arylation of aldehydes catalyzed by fluorinated NHC–Rh(i) complexes

“…[39][40][41][42][43] Furthermore, fluorinated-organic compounds exhibit interesting supramolecular interactions, for instance, they form hydrogen bonds with H-Y donors, [44][45][46][47][48][49] and in the case of aromatic fluorinated-molecules, they promoted the formation of p-p interactions with electron rich arenes. [50][51][52][53][54] Complexes with ligands that promote hydrogen bonding or p-p interactions were very interesting, since both interactions affect the catalytic activity [55][56][57] and selectivity of the catalysts. 58,59 Thus, for our study we selected NHC ligands derived from imidazo [1,5-a]pyridine due to their facile preparation, as well as the formation of very stable complexes, and the wide range of fluorinated-anilines commercially available.…”