In aqueous solutions of titanium(III) between pH 1.0 and 3.5 a single line e.s.r. signal is recorded with g = 1.9408 ± 0.001 and linewidth 95 ± 3 G. Evidence is presented in support of a hydrolyzed ...metal ion complex Ti(OH)
2
(H
2
O)
4
+
as the likely active species.
Strongly acidic aqueous solutions of titanium(III) chloride, bromide, iodide, or sulfate (0.02 M metal ion) provide no detectable e.s.r. signal at room temperature. In the frozen solution (77 K) an ...identical spectrum is observed from each sample with Formula: see text A maximum signal is observed at 6–8 M added anion, indicating not all titanium(III) species are e.s.r. active. Analysis indicates that the local symmetry of the Ti
3+
(3d
1
) ions providing the signal is D
3
. It is proposed that these ions are Ti(H
2
O)
6
3+
species located in sites in the ice structure subject to a strong asymmetric electric field from nearby counter ions. Since the spectrum is independent of anion, the counter ions are unlikely to be in the first or second coordination shell of the Ti
3+
.
In aqueous solutions of titanium(III) between pH 1.0 and 3.5 a single line e.s.r. signal is recorded with g = 1.9408 ± 0.001 and linewidth 95 ± 3 G. Evidence is presented in support of a hydrolyzed ...metal ion complex Ti(OH)
2
(H
2
O)
4
+
as the likely active species.
At pH 1.0-1.6 aqueous titanium(III) solutions containing added fluoride ion exhibit e.s.r. signals of trans-Ti(H
2
O)
4
F
2
+
, g = 1.9460 ± 0.0005, a
Ti
= 17.9 ± 0.2 G. The variation in the ...intensity of the optical and e.s.r. spectra with added fluoride ion indicate > 90% conversion to the complex at Ti:F = 1:2. The trans geometry of the complex is established from the spectrum in D
2
O, a 1:2:1 triplet with a
F
= 7.5 ± 0.5 G, and from the axial symmetry (D
4h
) apparent in the frozen solution spectrum,
The optical spectrum shows two bands assigned to the
2
B
2g
→
2
B
1g
(15 200 cm
−1
) and
2
B
2g
→
2
A
1g
(23 300 cm
−1
) transitions. Calculations based on the e.s.r. and optical spectra suggest covalent character in the in-plane π and σ bonding of the complex.A des pH allant de 1.0 à 1.6, des solutions aqueuses de titane(III) contenant des ions fluorures ajoutés, montrent un signal r.p.e. du Ti(H
2
O)
4
F
2
+
-trans, g = 1.9460 ± 0.0005, a
Ti
= 17.9 ± 0.2 G. On note une variation de l'intensité des spectres optique et r.p.e. lorsqu'on ajoute des ions fluorures; cette variation indique que la conversion vers le complexe est plus grande que > 90% lorsque la concentration de Ti:F = 1:2. On a établi que le complexe possède la géométrie trans en se basant sur le spectre dans le D
2
O alors qu'on observe un triplet 1:2:1 avec a
F
= 7.5 ± 0.5 G et aussi sur l'existence d'une symétrie axiale (D
4h
) observée pour le spectre de la solution congelée
Strongly acidic aqueous solutions of titanium(III) chloride, bromide, iodide, or sulfate (0.02 M metal ion) provide no detectable e.s.r. signal at room temperature. In the frozen solution (77 K) an ...identical spectrum is observed from each sample with
A maximum signal is observed at 6-8 M added anion, indicating not all titanium(III) species are e.s.r. active. Analysis indicates that the local symmetry of the Ti
3+
(3d
1
) ions providing the signal is D
3
. It is proposed that these ions are Ti(H
2
O)
6
3+
species located in sites in the ice structure subject to a strong asymmetric electric field from nearby counter ions. Since the spectrum is independent of anion, the counter ions are unlikely to be in the first or second coordination shell of the Ti
3+
.
