Photo- and thermochemistry of cis-(Cr(en)/sub 2/F/sub 2/)/sup +/ and cis-(Cr(en)/sub 2/F(H/sub 2/O))/sup 2 +/ in acidic aqueous solution

Journal Article · Wed Dec 02 00:00:00 EST 1987 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00271a012· OSTI ID:5476934

Herbert, B; Reinhard, D; Saliby, M J; Sheridan, P S

The cis-(Cr(en)/sub 2/F/sub 2/)/sup +/ ion is shown to undergo three consecutive aquations in acidic aqueous solution, leading to cis-(Cr(en)/sub 2/F(H/sub 2/O)/sup 2 +/, (Cr(en)(en-H)F(H/sub 2/O)/sub 2/)/sup 3 +/, and (Cr(en)F(H/sub 2/O)/sub 3/)/sup 2 +/, respectively. Kinetic studies of the first reaction confirm earlier findings of an acid-catalyzed and an acid-independent path (k/sub obsd/ = k/sub 0/ + k/sub 1/(H/sup +/), with k/sub 0/ = 6.3 x 10/sup -4/ s/sup -1/ and k/sub 1/ = 4.8 x 10/sup -3/ M/sup -1/s/sup -1/ at 70/sup 0/C; for k/sub obsd/, ..delta..H* = 90.8 +/- 1.0 kJ mol/sup -1/ and ..delta..S* = -40.7 +/- 2.4 J mol/sup -1/ K/sup -1/). Ring opening upon aquation of cis-(Cr(en)/sub 2/F(H/sub 2/O))/sup 2 +/ is not acid catalyzed (k = 1.88 x 10/sup -4/ s/sup -1/ at 70/sup 0/C, ..delta..H* = 83.4 +/- 1.9 kJ mol/sup -1/, and ..delta..S* = 74.0 +/- 3.8 J mol/sup -1/ K/sup -1/). Ligand field irradiation of cis-(Cr(en)/sub 2/F/sub 2/)/sup +/ in acidic solution causes efficient (phi = 0.35 +/- 0.04) amine labilization; the resulting (Cr(en)(en-H)F/sub 2/(H/sub 2/O))/sup 2 +/ loses monodentate ethylenediamine when heated in solution. The cis-(Cr(en)/sub 2/F(H/sub 2/O))/sup 2 +/ ion is also photosensitive, generating (Cr(en)(en-H)F(H/sub 2/O)/sub 2/)/sup 3 +/ and (Cr(en-H)/sub 2/F/sub 2/(H/sub 2/O)/sub 2/)/sup 2 +/ in successive photoinduced aquations. The photochemical results are discussed in terms of available photoliability models.

• Research Organization: Colgate Univ., Hamilton, NY
• OSTI ID: 5476934
• Journal Information: Inorg. Chem.; (United States), Vol. 26:24
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHROMIUM COMPLEXES
HYDRATION
PHOTOCHEMISTRY
THERMODYNAMIC PROPERTIES
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
PH VALUE
CHEMISTRY
COMPLEXES
DATA
DISPERSIONS
INFORMATION
KINETICS
MIXTURES
NUMERICAL DATA
PHYSICAL PROPERTIES
REACTION KINETICS
SOLUTIONS
SOLVATION
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry