ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The two complexes [Ir4(CO)10(diarsine)] (1) and [Ir4(CO)10(1,5-cyclooctadiene)] (2) bear a bidentate ligand chelating one metal atom of the basal face of the Ir4 tetrahedron. However, they differ in fluxional behaviour as observed by 2D-exchange and variable-temperature 13C-NMR. The CO-site exchange with lowest activation energy proceeds via an unbridged intermediate in 2, whereas that in 1 occurs via a concerted edge-bridging of CO's to an alternative face of the metal core. This difference is apparently related to different ground-state geometries: the basal CO's are symmetrically bridging in 2, whereas two CO's are semi-bridging in 1. The molecular structure of 2 was determined by single crystal X-ray diffractometry. The crystals are orthorhombic, space group Pbca, a = 11.651(4), b = 13.118(3), c = 28.64(1)Å. The idealized molecular symmetry is Cs. The diolefin chelates a basal Ir-atom replacing an axial and a radial CO group on the tetrahedral metal-atom framework.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19880710807
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