Molecular hydrogen complexes. 5. Electronic control of eta/sup 2/-H/sub 2/ versus dihydride coordination. Dihydride structure of MoH/sub 2/(CO)(R/sub 2/PC/sub 2/H/sub 4/PR/sub 2/)/sub 2/ for R = Et, i-Bu versus eta/sup 2/-H/sub 2/ for R = Ph
Since their discovery, new examples of transition-metal molecular-hydrogen (M-eta/sup 2/-H/sub 2/) complexes have been established at an increasingly rapid pace, including several complexes previously formulated as classical hydrides (e.g., FeH/sub 4/ (PEtPh/sub 2/)/sub 3/). Equilibrium between dihydrogen and dihydride ligands has been observed in solution, /sup 2a,2d/ emphasizing that eta/sup 2/-H/sub 2/ complexes can be considered tautomers of hydrides and not merely arrested intermediates in hydride formation. Much remains to be learned about these complexes which represent the first examples of coordination of a sigma bond to a metal. In particular, the electronic (e.g., ligand basicity) and steric (ligand bulk) factors which stabilize H/sub 2/ binding are not yet completely understood. The authors report here the preparation of a series of complexes in which the fate of hydrogen addition (eta/sup 2/-H/sub 2/ versus dihydride binding) rests primarily upon the basicity of the metal center as dictated by the electron-donating ability of ancillary phosphine ligands.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- OSTI ID:
- 7256183
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 109:26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN COMPLEXES
CHEMICAL PREPARATION
MOLYBDENUM COMPLEXES
EXPERIMENTAL DATA
LIGANDS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PH VALUE
PHOSPHINES
COMPLEXES
DATA
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
PHOSPHORUS COMPOUNDS
RESONANCE
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties