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

Related Subjects

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