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Conformational Rigidity in Complexes [ M Cl( t Bu 2 PH) 3 ] ( M = Rh, Ir)
Author(s) -
Böttcher HansChristian,
Mayer Peter
Publication year - 2017
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201700191
Subject(s) - chemistry , iridium , rhodium , denticity , ligand (biochemistry) , dissociation (chemistry) , crystallography , conformational isomerism , stereochemistry , cyclooctene , nuclear magnetic resonance spectroscopy , nmr spectra database , medicinal chemistry , molecule , crystal structure , catalysis , spectral line , organic chemistry , biochemistry , receptor , physics , astronomy
Reactions of [{ M (μ‐Cl)(coe) 2 } 2 ] ( M = Rh, Ir; coe = cis ‐cyclooctene) with the secondary phosphane t Bu 2 PH under various molar ratios were investigated. Probably, for kinetic reasons, the reaction behavior of the rhodium species differed from that of the iridium analogue in some instances. During these studies complexes [ M Cl( t Bu 2 PH) 3 ] [ M = Rh ( 1 ), Ir ( 2 )] were isolated, and solution variable‐temperature 31 P{ 1 H} NMR studies revealed that these complexes show a conformational rigidity on the NMR time scale. Spectra recorded in the temperature range from 173 to 373 K indicated in each case only one rotamer containing three chemically nonequivalent phosphanes due to the restricted rotation of these ligands about the M –P bonds and the tert ‐butyl substituents around the P–C( t Bu) bonds, respectively. Compound 1 showed in solution already at room temperature in several solvents a dissociation of a phosphane ligand affording the known complex [{Rh(μ‐Cl)( t Bu 2 PH) 2 } 2 ] beside the free phosphane. In contrast to these findings, the iridium analogue 2 remained completely unchanged under similar conditions and exhibited, therefore, some kinetic inertness. For a better understanding of the NMR spectroscopic investigations, the molecular structure of 1 in the solid state was confirmed by X‐ray crystallography.