“…The 1 H NMR spectral data of cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are given in the Experimental Section, and the peaks are assigned according to the following diagram: When compared to the free uncoordinated ligand, the H6 proton of the cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ complex shows a significant downfield shift (8.7 and 9.1 ppm, respectively), which is consistent with a cis arrangement where the π-cloud of the adjacent ligand induces a diamagnetic anisotropic effect. The 1 H NMR data clearly indicate that the pyridines within each bpy ligand in cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are magnetically nonequivalent. − As a result, out of the possible 8-proton resonance peaks, seven distinct bands were observed in DMSO solvent with the peaks for the H5 and H4‘ protons overlaping. …”
Section: Resultsmentioning
confidence: 98%
“…The 1 H NMR data clearly indicate that the pyridines within each bpy ligand in cis-[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are magnetically nonequivalent. [30][31][32] As a result, out of the possible 8-proton resonance peaks, seven distinct bands were observed in DMSO solvent with the peaks for the H5 and H4′ protons overlaping.…”
Rapid-scan stopped-flow kinetic studies show that the
multielectron oxidation of coordinated ammonia in
cis-[Ru(bpy)2(NH3)2]2+
by acidic (pH 0.5−1.3) aqueous chlorine provides the nitrosyl complex
cis-[Ru(bpy)2(NH3)(NO)]3+ as the final product. The first step in this
process involves the metal-centered oxidation of
cis-[Ru(bpy)2(NH3)2]2+ to
cis-[Ru(bpy)2(NH3)2]3+,
and the rate law for this process is −d[Ru(II)]/dt
=
2k
1[Ru(II)][Cl2]
with the
second order rate constant, k
1, as (1.1 ± 0.1)
× 103 M-1
s-1. Independent studies conducted on
the cis-[Ru(bpy)2(NH3)2]3+ complex show that
conversion to the nitrosyl complex follows an A → B → C type
consecutive pathway
with k
slow and k
fast
components, respectively. In the pH range of 0.5−2.8, the
k
slow process follows a competitive
pathway where both Cl2 and HOCl react with deprotonated
coordinated ammonia. The rate law for the
k
slow process
has the form k
slow =
{(k
2[H+][Cl-]
+
k
3
K
Cl)/(K
Cl
+
[H+][Cl-])}([Cl2]tot/[H+]),
where K
Cl corresponds to the
equilibrium
constant for the hydrolysis of Cl2. The rate constant
k
2, corresponding to the Cl2 term,
is 6.5 ± 0.3 s-1 while the
rate constant k
3, corresponding to the HOCl
reaction, is 2.0 ± 0.2 s-1. The
k
fast process involves further
oxidation
of intermediate B by Cl2. The intermediate of this
reaction is speculated as either a nitrene, nitrido, or
chloroamine
complex. The kinetic studies indicate that the conversion of this
unidentified intermediate to the final nitrosyl complex
proceeds through a fast preequilibrium, involving deprotonation of the
intermediate, followed by a direct attack by
Cl2. The rate law corresponding to the
k
fast process has the form
k
fast =
[k
4
K
int[Cl2]tot[H+][Cl-]]/[{K
int
+
[H+]}{[H+][Cl-]
+ K
Cl}], the equilibrium constant
K
int for the deprotonation process is 0.11 ±
0.04 M, and the rate
constant k
4 is (7.8 ± 1.5) × 102
M-1
s-1.
“…The 1 H NMR spectral data of cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are given in the Experimental Section, and the peaks are assigned according to the following diagram: When compared to the free uncoordinated ligand, the H6 proton of the cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ complex shows a significant downfield shift (8.7 and 9.1 ppm, respectively), which is consistent with a cis arrangement where the π-cloud of the adjacent ligand induces a diamagnetic anisotropic effect. The 1 H NMR data clearly indicate that the pyridines within each bpy ligand in cis -[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are magnetically nonequivalent. − As a result, out of the possible 8-proton resonance peaks, seven distinct bands were observed in DMSO solvent with the peaks for the H5 and H4‘ protons overlaping. …”
Section: Resultsmentioning
confidence: 98%
“…The 1 H NMR data clearly indicate that the pyridines within each bpy ligand in cis-[Ru(bpy) 2 (NH 3 ) 2 ] 2+ are magnetically nonequivalent. [30][31][32] As a result, out of the possible 8-proton resonance peaks, seven distinct bands were observed in DMSO solvent with the peaks for the H5 and H4′ protons overlaping.…”
Rapid-scan stopped-flow kinetic studies show that the
multielectron oxidation of coordinated ammonia in
cis-[Ru(bpy)2(NH3)2]2+
by acidic (pH 0.5−1.3) aqueous chlorine provides the nitrosyl complex
cis-[Ru(bpy)2(NH3)(NO)]3+ as the final product. The first step in this
process involves the metal-centered oxidation of
cis-[Ru(bpy)2(NH3)2]2+ to
cis-[Ru(bpy)2(NH3)2]3+,
and the rate law for this process is −d[Ru(II)]/dt
=
2k
1[Ru(II)][Cl2]
with the
second order rate constant, k
1, as (1.1 ± 0.1)
× 103 M-1
s-1. Independent studies conducted on
the cis-[Ru(bpy)2(NH3)2]3+ complex show that
conversion to the nitrosyl complex follows an A → B → C type
consecutive pathway
with k
slow and k
fast
components, respectively. In the pH range of 0.5−2.8, the
k
slow process follows a competitive
pathway where both Cl2 and HOCl react with deprotonated
coordinated ammonia. The rate law for the
k
slow process
has the form k
slow =
{(k
2[H+][Cl-]
+
k
3
K
Cl)/(K
Cl
+
[H+][Cl-])}([Cl2]tot/[H+]),
where K
Cl corresponds to the
equilibrium
constant for the hydrolysis of Cl2. The rate constant
k
2, corresponding to the Cl2 term,
is 6.5 ± 0.3 s-1 while the
rate constant k
3, corresponding to the HOCl
reaction, is 2.0 ± 0.2 s-1. The
k
fast process involves further
oxidation
of intermediate B by Cl2. The intermediate of this
reaction is speculated as either a nitrene, nitrido, or
chloroamine
complex. The kinetic studies indicate that the conversion of this
unidentified intermediate to the final nitrosyl complex
proceeds through a fast preequilibrium, involving deprotonation of the
intermediate, followed by a direct attack by
Cl2. The rate law corresponding to the
k
fast process has the form
k
fast =
[k
4
K
int[Cl2]tot[H+][Cl-]]/[{K
int
+
[H+]}{[H+][Cl-]
+ K
Cl}], the equilibrium constant
K
int for the deprotonation process is 0.11 ±
0.04 M, and the rate
constant k
4 is (7.8 ± 1.5) × 102
M-1
s-1.
“…The same arguments apply to the other two terms which appear in eq 19, and so to lowest nonvanishing order we may write the contribution to the dipole strength which arises from static-vibrational interactions as Z)VS(A->-J) = DrVS(A-»J) (21) Note that the additivity properties with respect to the vibrational perturbations are preserved in eq 21. Since the magneto-optical B term has the same symmetry properties as the dipole strength, we may write ß( ->J) as S(A^J) = SV(A^J) + BS(A^J) + fivs(A-*J) + higher-order terms = *,V(A-J) + Srs(A-J) r + 5rVS(A-*-J) + higher-order terms (22) Here Bf is the purely vibrational contribution of the nontotally symmetric normal mode Qr to the B term associated with the | A) -| J) transition, 5rs is the purely static contribution of £/(T), and Brws is the contribution of static-vibrational interactions. Brws is of second order in the normal coordinate Qr and first order in the totally symmetric component of the static perturbation.…”
range of solvent effects and demonstrate that back-bonding from ruthenium(II) can indeed increase electron density at remote ligand sites. The protonated species, as well as the Co(III) and Rh(III) complexes, manifest significant charge withdrawal. The 7-carbon resonances are much larger than solvent effects and indicate electron density depletion in the order H+ > Co(III) > Rh(III) and increase with Ru(II) > Fe(II).The effect of substituents indicates that the extent of charge delocalization by x back-bonding is greatest for the ligand which is most depleted in electron density. Thus, one expects that fV-methylpyrazinium and the pyrazinium ion would be more stabilized than pyrazine by the x back-bonding of pentaammineruthenium(II), as found by Malin et al. for the corresponding pentacyanoferrate(II) complexes,4 supporting an earlier conclusion2 that the most important factor in causing the increased basicity of pyrazine when it is complexed to Ru(II) is the stabilization of the protonated pyrazine by the ruthenium center.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
