Intrazeolite chemistry of nickel(0) complexes and Ni(0,II) clusters studied by EXAFS, solid state NMR, and FR-IR spectroscopy
Adsorption, thermal decomposition, and reactivity of NI(CO)/sub 4/ in the cage system of dehydrated zeolite Y has been studied with EXAFS and near-edge spectroscopies, in particular monitoring changes in oxidation states and Ni ligation. Ni(CO)/sub 4/ is adsorbed as an intact molecule in cation-free zeolite Y, LiY, and NaY. Symmetry changes of the molecule in LiY and NaY are assigned to the formation of cation--OC-Ni bridges. Thermal treatment of the Ni(CO)/sub 4/NaY adduct leads to loss of CO concomitant with the formation of a bimodal Ni phase. A major part of the Ni forms small clusters (approximately 0.5 to 1.5 nm), in addition to larger crystallites (5-30 nm), sticking at the outer surface of the zeolite crystals. Oxidation of Ni(CO)/sub 4/NaY to NiONaY with molecular oxygen occurs almost to completion below 295 K. The small NiO particles are stable to sintering up to 670 K. Nickel-phosphineNaY adducts have been prepared by direct adsorption from solution (Ni(CO)/sub 3/PMe/sub 3/, Ni(CO)/sub 2/(PMe/sub 3/)/sub 2/), and by synthesis inside the NaY supercage (Ni(CO)/sub 3/PMe/sub 3/, Ni(CO)/sub 3/(PPh/sub 2/CHMe/sub 2/), Ni(CO)/sub 3/P(tau-Bu)/sub 3/, Ni(PMe/sub 3/)/sub x/). The NaYNi(CO)/sub 3/(PPh/sub 2/CHMe/sub 2/) adduct is a ship-in-a bottle complex, i.e., the Ni complex is too large to exit the zeolite supercage. The substitution of carbonyl ligands by phosphines was monitored in the near-edge and EXAFS modulations as well as with /sup 31/P MAS NMR. EXAFS is an excellent method to monitor ligand coordination and provides information that is complimentary to IR spectroscopy.
- Research Organization:
- E.I. du Pont de Nemours and Company, Wilmington, DE (USA)
- DOE Contract Number:
- AS05-80ER10742
- OSTI ID:
- 7247445
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:6; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ADSORPTION
CARBONYLS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COMPLEXES
DATA
DECOMPOSITION
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
FLUORESCENCE
FOURIER TRANSFORM SPECTROMETERS
GRAVIMETRIC ANALYSIS
INFORMATION
INFRARED SPECTRA
ISOTOPES
LIGHT NUCLEI
LUMINESCENCE
MAGNETIC RESONANCE
MEASURING INSTRUMENTS
MICROSCOPY
NICKEL COMPLEXES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
QUANTITATIVE CHEMICAL ANALYSIS
RESONANCE
SORPTION
SPECTRA
SPECTROMETERS
STABLE ISOTOPES
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
TRANSITION ELEMENT COMPLEXES
VALENCE