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Variable Coordination Modes Realized with a Dihydroxyalkyldiphosphane as a Hemilabile Ligand: A Combined 103 Rh‐NMR and Density‐Functional Study
Author(s) -
Bühl Michael,
Baumann Wolfgang,
Kadyrov Renat,
Börner Armin
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19990609)82:6<811::aid-hlca811>3.0.co;2-o
Subject(s) - chemistry , rhodium , ligand (biochemistry) , cationic polymerization , butane , proton nmr , carbon 13 nmr , density functional theory , stereochemistry , center (category theory) , crystallography , computational chemistry , organic chemistry , catalysis , receptor , biochemistry
Cationic rhodium complexes of ( R , R )‐1,4‐bis(diphenylphosphanyl)butane‐2,3‐diol and cyclic diolefins exhibit temperature‐dependent 31 P‐ and 103 Rh‐NMR spectra which are best explained by a hemilabile coordination of one of the hydroxy groups to the rhodium center. A complex with this ligand bound in tridentate fashion is in equilibrium with a species with the common square‐planar ligand arrangement. The 103 Rh‐NMR shift of the fivefold coordinated complex is found almost 500 ppm downfield from that of a fourfold coordinated species. This effect is characteristic for an increase in coordination number. At gradient‐corrected levels of density‐functional theory, a corresponding species with an oxygen‐rhodium contact has been located, together with other isomers. The computed trends in energies and 103 Rh chemical shifts are consistent with the experimental findings.