Molecular hydrogen complexes of the transition metals. 7. Kinetics and thermodynamics of the interconversion between dihydride and dihydrogen forms of W(CO) sub 3 (PR sub 3 ) sub 2 H sub 2 where R = isopropyl and cyclopentyl

Journal Article · Wed May 09 00:00:00 EDT 1990 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00166a020· OSTI ID:6812015

Khalsa, G R.K.; Kubas, G J; Unkefer, C J; Van Der Sluys, L S; Kubat-Martin, K A ^[1]

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1. Los Alamos National Lab., NM (USA)

Kinetic and thermodynamic parameters have been obtained for the equilibrium system H{sub 2}W(CO){sub 3}(PR{sub 3}){sub 2} {rightleftharpoons} W(CO){sub 3}(PR{sub 3}){sub 2}({eta}{sup 2}-H{sub 2}). The systems studied include a newly synthesized complex where R = cyclopentyl. {sup 31}P NMR spin saturation transfer studies over a temperature range of 288-310 K afford values of {Delta}H{double dagger} = 10.1 {plus minus} 1.8 kcal/mol, {Delta}S{double dagger} = {minus}19.9 {plus minus} 6.0 eu, and {Delta}G{double dagger} = 16.0 {plus minus} 0.2 kcal/mol (298 K) for the dihydrogen to dihydride exchange process where R = isopropyl. Exchange between nonequivalent hydrides in the seven-coordinate dihydride complex corresponds to {Delta}G{double dagger} {approx} 11 kcal/mol (253 K) derived from NMR coalescence data. {sup 1}H({sup 31}P) NMR equilibrium studies for the formation of the dihydrogen complex from the dihydride complex over the temperature range 265-309 K produce the following: {Delta}H{degree} = {minus}1.2 {plus minus} 0.6 kcal/mol, {Delta}S{degree} = {minus}1.2 {plus minus} 2.1 eu, and {Delta}G{degree} = {minus}0.80 {plus minus} 0.12 kcal/mol (298 K).

• OSTI ID: 6812015
• Journal Information: Journal of the American Chemical Society; (USA), Vol. 112:10; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
TRANSITION ELEMENTS
HYDROGEN COMPLEXES
DATA ANALYSIS
EXPERIMENTAL DATA
HYDRIDES
KINETICS
MEASURING INSTRUMENTS
MEASURING METHODS
ORGANOMETALLIC COMPOUNDS
THERMODYNAMICS
COMPLEXES
DATA
ELEMENTS
HYDROGEN COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
400201* - Chemical & Physicochemical Properties