Characterization of (methylcyclopentadienyl)trimethylplatinum and low-temperature organometallic chemical vapor deposition of platinum metal
- Univ. of California, Los Angeles (USA)
({eta}{sup 5}-Methylcyclopentadienyl)trimethylplatinum, ({eta}{sup 5}-MeCp)PtMe{sub 3}, 1 (MeCp = CH{sub 3}C{sub 5}H{sub 4}), is synthesized from trimethylplatinum iodide and sodium methylcyclopentadienide by the method of Fritz and Schwarzhans. By using care in the purification of bis(methylcyclopentadiene) from dicyclopentadiene, a sample of 1 is obtained showing a melting point of 29.5-30.0{degree}C and a vapor pressure of 0.053 Torr at 23{degree}C, {sup 1}H and {sup 13}C NMR spectra have been obtained. Coupling constants to the cyclopentadienyl ring carbons are found to differ, Hz: {sup 195}Pt-{sup 13}C{sub Me} = 13.62, while {sup 195}Pt-{sup 13}C{sub H} = 2.82 or 5.34. Five separate resonances are observed for the ring carbon atoms of the MeCp group in the solid ({sup 1}H){sup 13}C NMR. However, only one signal is observed at {minus}73{degree}C or higher for the 3 methyl groups on Pt, indicating a low barrier for rotation of these groups in the solid state. The principal finding, of significance to the solid-state NMR, is the intermolecular contacts of 3.98, 4.55, and 4.94 {angstrom} between closest ring-carbon atoms on independent molecules in adjacent unit cells. These contacts are too close to permit rotation of the MeCp rings. The ring is pentahapto-bonded with almost identical Pt to ring-carbon distances within the limited accuracy of this determination, {angstrom}, C{sub (Me)}-Pt = 2.266, C{sub (H)}-Pt = 2.260, 2.314, 2.354, and 2.324. For deposition of metallic platinum, a stream of Ar gas at ambient pressure is first saturated with the vapor of 1 at 23{degree}C. This is then conducted into a chamber containing H{sub 2} gas such that the ratio of saturated Ar:H{sub 2} = 4:1. A substrate such as a glass slide or a Si(100) wafer, placed near the outlet of the saturated Ar gas stream and heated to 120{degree}, becomes coated with a film of highly reflective Pt metal.
- OSTI ID:
- 7197763
- Journal Information:
- Journal of the American Chemical Society; (USA), Vol. 111:24; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
PLATINUM
CHEMICAL VAPOR DEPOSITION
DATA ANALYSIS
ELECTRONIC EQUIPMENT
EXPERIMENTAL DATA
MEASURING INSTRUMENTS
MEASURING METHODS
ORGANOMETALLIC COMPOUNDS
THIN FILMS
CHEMICAL COATING
DATA
DEPOSITION
ELEMENTS
EQUIPMENT
FILMS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLATINUM METALS
SURFACE COATING
TRANSITION ELEMENTS
360603* - Materials- Properties
400201 - Chemical & Physicochemical Properties