Models for reactions of acetylene on platinum(111): a vinyl(acetylene)triplatinum complex and evidence for an ethylidyne intermediate
Reaction of (Pt/sub 3/(..mu../sub 3/-H)(..mu..-dppm)/sub 3/)/sup +/ (1) with excess acetylene gives (Pt/sub 3/(CH=CH/sub 2/)(..mu../sub 3/-eta/sup 2/(parallel)-HCCH)(..mu..-dppm)/sub 3/)/sup +/, where dppm = Ph/sub 2/PCH/sub 2/PPh/sub 2/. Deuterium-labeling studies indicate that H-D scrambling occurs within the vinyl group but not in the acetylene ligand. For example, (Pt/sub 3/(..mu../sub 3/-D)(..mu..-dppm)/sub 3/)/sup +/ with HCCH gave (Pt/sub 3/(CH==CH/sub 7/-d/sub 1/)(..mu../sub 3/-eta/sup 2/(parallel)-HCCH)(..mu..-dppm)/sub 3/)/sup +/, in which the deuterium label was distributed randomly in all three possible positions in the vinyl group. It is possible that this scrambling occurs by way of a short-lived ethylidyne intermediate. The complex is fluxional, due to rotation of the acetylene ligand, at room temperature. Similar reaction of 1 with excess propyne gives (Pt/sub 3/(CH=CHMe)(..mu../sub 3/-eta/sup 2/(**)-MeCCH)(..mu..-dppm)/sub 3/)/sup +/, but this complex is not fluxional at room temperature and is formed selectively by cis insertion of propyne into the Pt-H groups. There is a strong resemblance to the chemistry resulting from chemisorption of acetylene on a Pt(111) surface, thus providing a clear example of the value of coordinatively unsaturated clusters as mimics of metal surfaces.
- Research Organization:
- Univ. of Western Ontario, London (Canada)
- OSTI ID:
- 6969945
- Journal Information:
- Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 7:7; ISSN ORGND
- Country of Publication:
- United States
- Language:
- English
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Models for reactions of acetylene on platinum (111): the. mu. /sub 3/-eta/sup 2/-acetylene derivative
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ALKYNES
CATALYSTS
CHEMICAL REACTIONS
DATA
DEUTERIUM COMPOUNDS
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
LABELLING
MATHEMATICAL MODELS
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM
PLATINUM METALS
REACTION INTERMEDIATES
SURFACE PROPERTIES
SURFACES
TRANSITION ELEMENTS