Synthesis and reactivity of ((eta/sup 5/-C/sub 5/R/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ (R = H, CH/sub 3/) complexes of naphthalene, anthracene, pyrene, chrysene, and azulene. Kinetic studies of arene displacement reactions in acetonitrile solutions

Journal Article · Wed Jul 16 00:00:00 EDT 1986 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00235a008· OSTI ID:6539573

McNair, A M; Mann, K R

The synthesis and characterization of new ((eta/sup 5/-C/sub 5/H/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ and ((eta/sup 5/-C/sub 5/(CH/sub 3/)/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ complexes are reported (arene = naphthalene, anthracene, pyrene, chrysene, azulene). Kinetic studies of arene displacement by acetonitrile for five of these complexes are reported. The values obtained for k/sub obsd/ range from 1.3 x 10/sup -2/ s/sup -1/ to 4.6 x 10/sup -6/ s/sup -1/ in 2.73 M CH/sub 3/CN. The differences between the rates observed for the C/sub 5/H/sub 5//sup -/ complexes and the C/sub 5/(CH/sub 3/)/sub 5//sup -/ compound are explained in terms of an associative mechanism. Rate constants for the ruthenium compounds containing pyrene and chrysene were found to be approximately 4 orders of magnitude larger, respectively, than those for the corresponding Fe complexes. This is believed to be an effect of the difference in the sizes of the two metals and their subsequent susceptibility toward nucleophilic attack. The temperature and concentration dependence of the rate constant k was studied for the reaction of (eta/sup 5/-C/sub 5/(CH/sub 3/)/sub 5/)Ru(eta/sub 6/-anthracene))/sup +/ with CH/sub 3/CN. The ..delta..S double dagger of -13.3 (9) eu and ..delta..H double dagger = +14.9 (3) kcal/mol confirm the associative nature of the displacement reaction. The straight-line plot obtained for k/sub obsd/ vs. (CH/sub 3/CN) is consistent with a rate equation of the general form rate = k(M)(CH/sub 3/CH) where (M) is the concentration of the metal complex. Two mechanisms consistent with the data are proposed and discussed; on includes a preequilibrium between a eta/sup 6/-arene metal complex and a eta/sup 4/-arene species, while the other involves direct nucleophilic attack on the metal-center of the eta/sup 6/ complex.

• Research Organization: Univ. of Minnesota, Minneapolis
• DOE Contract Number: AC02-83ER13103
• OSTI ID: 6539573
• Journal Information: Inorg. Chem.; (United States), Vol. 25:15
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTHRACENE
CHEMICAL PREPARATION
CHEMICAL REACTIONS
AZULENE
CHRYSENE
FLUORINE COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHOSPHORUS COMPOUNDS
PYRENE
RUTHENIUM COMPLEXES
AROMATICS
COMPLEXES
CONDENSED AROMATICS
HALOGEN COMPOUNDS
HYDROCARBONS
ORGANIC COMPOUNDS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties