Measurements were recorded with
a Bio-Logic SP-150 potentiostat/galvanostat and the EC-Lab software
suite. All experiments were performed in a three-electrode system
cell configuration that consisted of a glassy-carbon (ø = 3.0
mm) as working electrode (CH Instruments, USA), a Pt wire as the counter
electrode (CH Instruments, USA), and an Ag/Ag+ nonaqueous
reference electrode with 0.01 M AgNO3 in 0.1 M [nBu4N][PF6] in acetonitrile
(BASi, USA). The supporting electrolyte, [nBu4N][PF6] was purchased from Sigma-Aldrich,
recrystallized three times using hot ethanol, and stored under dynamic
vacuum for a minimum of 2 days prior to use. All electrochemical measurements
were performed at room temperature in a nitrogen-filled drybox. CV
cells were prepared with 0.50 mM cluster 1, 0.25 mM cluster 2 (cluster
1 and 2 referring to any pair of clusters differing only by two hydroxy
ligands), 0.1 M [nBu4N][PF6], and 50 mM buffer in acetonitrile. OCP was allowed to stabilize
(5 min to 1 h) before titration of 100 μL of cluster 2 into
the CV cell. Automated titrations were carried out by an NE-1000 One
Channel Programmable Syringe Pump for 3–10 repetitions. Upon
the conclusion of electrochemical experiments, ferrocene was added
to the sample as an internal standard and an additional CV was collected.
a Bio-Logic SP-150 potentiostat/galvanostat and the EC-Lab software
suite. All experiments were performed in a three-electrode system
cell configuration that consisted of a glassy-carbon (ø = 3.0
mm) as working electrode (CH Instruments, USA), a Pt wire as the counter
electrode (CH Instruments, USA), and an Ag/Ag+ nonaqueous
reference electrode with 0.01 M AgNO3 in 0.1 M [nBu4N][PF6] in acetonitrile
(BASi, USA). The supporting electrolyte, [nBu4N][PF6] was purchased from Sigma-Aldrich,
recrystallized three times using hot ethanol, and stored under dynamic
vacuum for a minimum of 2 days prior to use. All electrochemical measurements
were performed at room temperature in a nitrogen-filled drybox. CV
cells were prepared with 0.50 mM cluster 1, 0.25 mM cluster 2 (cluster
1 and 2 referring to any pair of clusters differing only by two hydroxy
ligands), 0.1 M [nBu4N][PF6], and 50 mM buffer in acetonitrile. OCP was allowed to stabilize
(5 min to 1 h) before titration of 100 μL of cluster 2 into
the CV cell. Automated titrations were carried out by an NE-1000 One
Channel Programmable Syringe Pump for 3–10 repetitions. Upon
the conclusion of electrochemical experiments, ferrocene was added
to the sample as an internal standard and an additional CV was collected.