Rh2[(R)-(+)-MTPA]4 as an NMR auxiliary for the enantiodifferentiation of chiral secondary and tertiary phosphine–borane complexes

Complexation of rhodium(II) tetracarboxylates with aliphatic diamines in solution: 1H and 13C NMR and DFT investigations

“…In addition, we performed a DFT modelling of hypothetical equatorial adducts of 1 with Rh 2 (AcO) 4 and attempted to predict their NMR properties. Selected experimental 1 H and 13 C NMR chemical shifts and complexation shifts together with the complete results of DFT calculations (atomic coordinates, calculated 1 H, 13 C and 15 N chemical shifts) were given as supporting information. Selected calculated 1 H and 15 N chemical shifts were gathered in the Experimental section.…”

“…These salts act as chiral recognition agents. By this, one could determine either the optical purity of a compound or, in certain cases, its absolute configuration . For the proper application of dirhodium methods, it is essential to know the plausible adduct structures and the details of complexation processes.…”

“…These parameters were positive for 1 H (>0 ppm) and either positive or negative for 13 C. In the fast ligand exchange regime, the decrease of Δδ magnitude in the course of titration implied the increase of molar ratio of free ligand to complex. (v) The use of multifunctional amines, such as 1,2-diazabicyclo[2,2,2]octane or 1,3,5,7-tetraazatricyclo [3,3,1,13,7]decane, resulted in polymeric adducts, insoluble in organic solvents. [30] This work is a continuation of our previous investigations and reports some NMR results on the complexation of rhodium(II) tetracarboxylates (Rh-Rh) with some aliphatic diamines (L-L) in CDCl 3 solution ( Fig.…”

Adducts of nitrogenous ligands with rhodium(II) tetracarboxylates and tetraformamidinate: NMR spectroscopy and density functional theory calculations

“…There are two NMR methods based on the ability of dirhodium salts to the formation of axial adducts. The first method makes use of optically pure rhodium(II) tetracarboxylates (usually Mosher's acid salts) as chiral recognition agent and is designed to the determination of optical purity of chiral compounds by NMR methods . The second application allows one to establish the compound configuration ( R or S ) by NMR spectroscopy .…”

“…The first method makes use of optically pure rhodium(II) tetracarboxylates (usually Mosher's acid salts) as chiral recognition agent and is designed to the determination of optical purity of chiral compounds by NMR methods. [2][3][4][5][6][7][8][9][10][11][12] The second application allows one to establish the compound configuration (R or S) by NMR spectroscopy. [13][14][15][16] The latter is based on the careful analysis of NOE interactions between ligand and chiral dirhodium salt core and on the analysis of chemical shift variations in ligand because of the complexation.…”