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Synthesis, Solid‐State Structure and Multinuclear NMR Studies of the New Polyhydrido Iridium Carbonyl Cluster Ir 4 H 4 (μ‐H) 4 (CO) 4 (PPh 3 ) 4
Author(s) -
Garlaschelli Luigi,
Greco Francesco,
Peli Giulia,
Manassero Mario,
Sansoni Mirella,
Gobetto Roberto,
Salassa Luca,
Della Pergola Roberto
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200200690
Subject(s) - chemistry , iridium , hydride , crystallography , infrared spectroscopy , hydrogen , nuclear magnetic resonance spectroscopy , toluene , cluster (spacecraft) , nmr spectra database , ligand (biochemistry) , hydrogen atom , stereochemistry , spectral line , catalysis , organic chemistry , astronomy , biochemistry , physics , receptor , computer science , programming language , alkyl
The carbonyl hydride cluster Ir 4 H 8 (CO) 4 (PPh 3 ) 4 ( 1 ) has been formed in high yield and purity by heating a mixture of Ir 4 (CO) 12 and PPh 3 in toluene at 90 °C under hydrogen at atmospheric pressure. The product has been characterised by microanalysis, spectroscopy (IR, 1 H and 31 P NMR) and X‐ray diffraction. In the solid state one hydrogen, one CO and one triphenylphosphane ligand are terminally bonded to each iridium atom, whereas four hydride ligands are bridging. All the hydrogen atoms were directly located by X‐ray analysis at an average H−Ir distance of 1.55 Å (for the terminal H) and 1.75 Å (for the μ‐H). As shown by 1 H and 31 P NMR spectra, two isomeric forms ( 1A and 1B ) of the cluster are present in CD 2 Cl 2 solution at room temperature, and they do not interconvert in the explored temperature range. However, if a solid sample of the cluster is dissolved at 188 K, only 1A is detected by NMR spectroscopy. The structure of 1B could be proposed on the basis of the T 1 relaxation times of the various hydrides: it results by localised exchange of H and CO around two vertices of the tetrahedral frame. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)