Linkage isomerization of (urea)pentaammineruthenium(III) and inter- vs intramolecular substitution on ruthenium(III)

Journal Article · Wed Sep 25 00:00:00 EDT 1985 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00214a023· OSTI ID:6142305

Fairlie, D P; Taube, H

The selective syntheses, characterization, and reactivities of pentaammineruthenium(III) complexes of N- and O-bound urea are described. Under conditions where the coordinated urea ligand is not deprotonated (pH < 2), the N-bonded isomer rearranges intramolecularly to the thermodynamically more stable O-bonded isomer (k/sub obsd/ = 9.1 x 10/sup -3/ s/sup -1/, 1.0 M CF/sub 3/SO/sub 3/H, 25.0/sup 0/C) without detectable parallel reactions. The N-bound form is much more acidic than the O-bound form (pK/sub a/ = 1.80 +/- 0.05, 25/sup 0/C, ..mu.. = 1.0 M (KCl); vs pK/sub a/ > 10), and the ratio of the former to the latter increases with pH according to the relation (K/sub a/ + (H/sup +/))/(H/sup +/). In aqueous media when pH > pK/sub a/, a facile intramolecular O- to N-linkage isomerization occurs (k/sub obsd/ = 1.3 x 10/sup -3/ s/sup -1/, pH 6.2, 0.1 M NaMes, ..mu.. = 1.0 M (NaCF/sub 3/SO/sub 3/), 25.0/sup 0/C) together with some parallel aquation of the O-bonded isomer (15%). The equilibrium governing the distribution of linkage isomers (K/sub eq/ = k/sup NO//k/sub s//sup ON/ approx. 9) hence favors O-coordination of the neutral urea molecule to Ru(III), but this preference is much less, as observed for Rh(III) (K/sub eq/ approx. 1), than that for the smaller first-row transition metals, Co(III) (approx. 240) and Cr(III) (> 10/sup 5/). In aqueous acid, ((NH/sub 3/)/sub 5/RuOC(NH/sub 2/)/sub 2/)/sup 3 +/ aquates to give ((NH/sub 3/)/sub 5/RuOH/sub 2/)/sup 3 +/ and urea. 44 references, 3 figures, 1 table.

• Research Organization: Stanford Univ., CA (United States)
• OSTI ID: 6142305
• Journal Information: Inorg. Chem.; (United States), Vol. 24:20
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
AMMINES
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
THERMODYNAMIC PROPERTIES
RUTHENIUM
RUTHENIUM COMPLEXES
UREA
EQUILIBRIUM
EXPERIMENTAL DATA
ISOMERIZATION
LIGANDS
NITROGEN
OXYGEN
PH VALUE
AMIDES
CARBONIC ACID DERIVATIVES
COMPLEXES
DATA
ELEMENTS
INFORMATION
KINETICS
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM METALS
REACTION KINETICS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
400201* - Chemical &amp; Physicochemical Properties
360104 - Metals &amp; Alloys- Physical Properties