Secondary Oxide Phosphines to Promote Tandem Acyl-Alkyl Coupling/Hydrogen Transfer to Afford (Hydroxyalkyl)rhodium Complexes. Theoretical and Experimental Studies.

Title Secondary Oxide Phosphines to Promote Tandem Acyl-Alkyl Coupling/Hydrogen Transfer to Afford (Hydroxyalkyl)rhodium Complexes. Theoretical and Experimental Studies.
Authors V. San Nacianceno; L. Ibarlucea; C. Mendicute-Fierro; A. Rodríguez-Diéguez; J.M. Seco; A.J. Mota; M.A. Garralda
Journal Inorg Chem
DOI 10.1021/acs.inorgchem.8b00320
Abstract

Acyl(?-norbornenyl)rhodium(III) dimer [Rh(?-Cl)(CHNCO)(CH)L] (1) (CH = ?-norbornenyl; L = 4-picoline, isoquinoline) reacts with diphenylphosphine oxide (SPO) to undergo a one-pot reaction involving (i) cleavage of the chloride bridges and coordination of the phosphine, (ii) C-C bond coupling between acyl and norbornenyl in a 18e species, and (iii) ligand-assisted outer-sphere O(P)-to-O(C) hydrogen transfer, to afford mononuclear 16e species [RhCl{(CHNC(O)CH)(PhPO)H}(L)] (2) containing a quinolinyl-(norbornenylhydroxyalkyl) fragment hydrogen-bonded to a ?- P-phosphinite ligand. Pentacoordinated 2, which adopt a distorted trigonal bipyramidal structure, are kinetic reaction products that transform into the thermodynamic favored isomers 3. Structures 3 contain an unusual weak ?-C anagostic interaction involving the rhodium atom and one carbon atom of the olefinic C-H bond of the norbornenyl substituent in the chelating quinolinyl-hydroxyalkyl moiety. Their structure can be described as pseudoctahedral, through a 5 + 1 coordination, with the anagostic interaction in a trans disposition with respect to the phosphorus atom of the phosphinite ligand. Complexes were characterized in solution by NMR spectroscopy and electrospray ionization mass spectrometry. Complex [RhCl{(CHNC(O)CH)(PhPO)H}(4-picoline)] (3a) was also identified by X-ray diffraction. Density functional theory calculations confirm the proposed structures by a plausible set of mechanisms that accounts for the 1 (monomer) ? 2 ? 3 transformation. Lowest-energy pathways involve reductive elimination of quinolinylnorbornenylketone, still coordinated in the rhodium(I) species thus formed, followed by O-to-O hydrogen transfer from ?- P-SPO to the sp hybridized carbonyl group (formal alkoxide) avoiding the otherwise expected classical release of ketone. Theoretical C NMR studies also confirm the experimental spectral data for the considered structures.

Citation V. San Nacianceno; L. Ibarlucea; C. Mendicute-Fierro; A. Rodríguez-Diéguez; J.M. Seco; A.J. Mota; M.A. Garralda.Secondary Oxide Phosphines to Promote Tandem Acyl-Alkyl Coupling/Hydrogen Transfer to Afford (Hydroxyalkyl)rhodium Complexes. Theoretical and Experimental Studies.. Inorg Chem. 2018. doi:10.1021/acs.inorgchem.8b00320

Related Elements

Rhodium

See more Rhodium products. Rhodium (atomic symbol: Rh, atomic number: 45) is a Block D, Group 9, Period 5 element with an atomic weight of 102.90550. Rhodium Bohr ModelThe number of electrons in each of Rhodium's shells is [2, 8, 18, 16, 1] and its electron configuration is [Kr] 4d8 5s1. The rhodium atom has a radius of 134 pm and a Van der Waals radius of 195 pm. Rhodium was discovered and first isolated by William Wollaston in 1804. In its elemental form, rhodium has a silvery white metallic appearance. Elemental RhodiumRhodium is a member of the platinum group of metals. It has a higher melting point than platinum, but a lower density. Rhodium is found in ores mixed with other metals such as palladium, silver, platinum, and gold. Rhodium is primarily used as the catalyst in the three-way catalytic converters of automobiles it is also highly valued in jewelry. The name Rhodium originates from the Greek word 'Rhodon,' which means rose.

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