Pseudopotential multireference single and double excited configuration interaction calculations of nickel-containing molecules. 4. HNiSiH sub 3 and HNiAlH sub 3 as minimum models of H chemisorption on a supported Ni atom

Journal Article · Thu Jun 13 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100165a037· OSTI ID:5975714

Haberlandt, H; Ritschl, F ^[1]; Pacchioni, G ^[2]

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1. Central Inst. of Physical Chemistry, Berlin (West Germany)
2. Univ. di Milano (Italy)

The chemisorption of atomic H on a Ni atom bound to SiH{sub 3} or AlH{sub 3} supporting fragments has been investigated by means of pseudopotential CI calculations. The two systems investigated, H-Ni-SiH{sub 3} and H-Ni-AlH{sub 3}, can be considered as minimum models of strong (SMSI) and weak (WMSI) metal-support interactions, respectively. It is found that the presence on the SiH{sub 3} support of a singly occupied dangling bond, not present on AlH{sub 3}, is the key factor determining the strong metal-support interaction. By this interaction, the Ni atom binds the adsorbed H atom less strongly than in the free NiH molecule. The chemisorption of H decreases also the Ni-substrate bond strength. This result, however, is found only after inclusion of correlation effects. Uncorrelated calculations show the opposite trend, that is, a reinforcement of both Ni-H and Ni-support bonds by H chemisorption. This contradictory result is probably the consequence of the different SCF and CI energy separation between the Ni 3d{sup 8}4s{sup 2} and 3d{sup 9}4s{sup 1} configurations. The formation of two covalent bonds, as in H-Ni-SiH{sub 3}, implies that the metal atom assumes a 3d{sup n}4s{sup 2}-like configuration more suitable to form directional 4sp hybrid orbitals. The case of Ni is compared with the limiting situations of Fe (3d{sup 6}4s{sup 2}) and Cu (3d{sup 10}4s{sup 1}) to generalize the conclusions about the electronic mechanisms with the limiting situations of Fe (3d{sup 6}4s{sup 2}) and Cu (3d{sup 10}4s{sup 1}) to generalize the conclusions about the electronic mechanisms of SMSI. For the model of WMSI, the authors found that in their system the interaction of a supported Ni with the approaching H atom induces the rupture of the Ni-substrate bond and the formation of a Ni-H molecule which easily desorbs from the surface.

• OSTI ID: 5975714
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:12; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN
CHEMISORPTION
NICKEL COMPOUNDS
SORPTIVE PROPERTIES
ALUMINIUM HYDRIDES
CONFIGURATION INTERACTION
ELECTRONIC STRUCTURE
MATHEMATICAL MODELS
MOLECULAR MODELS
NICKEL
NICKEL HYDRIDES
POTENTIAL ENERGY
SILANES
SUPPORTS
THEORETICAL DATA
ALUMINIUM COMPOUNDS
CHEMICAL REACTIONS
DATA
ELEMENTS
ENERGY
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
MECHANICAL STRUCTURES
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
SEPARATION PROCESSES
SILICON COMPOUNDS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties