Metallodithiolate ligands play an important role in providing the appropriate electronic environment for the catalytic function of various metalloenzymes; acetyl coA synthase serves as paradigm. Using tetradentate N_(2)S_(2) ligands to bind transition metals, a library of well-characterized synthetic analogues has been established. These metal-bound cis-dithiolates, display a wide range of reactivity, including S-based metallation, oxygenation, and alkylation. Sulfur's affinity for gold(I) is well known and typically follows Pearson's HSAB theory. With this in mind, the NiN_(2)S_(2) moieties were used to synthesize propeller-type nickel-gold complexes within a group of [Ni(N_(2)S_(2))_(x)Au_(y)] ( x = 1 or 2; y = 1, 2, or 4) complexes. The solid-state molecular structures of these square planar cis-dithiolate nickel complexes to which gold(I) is bound contain within them classical aurophilic interactions. Electrochemical studies reveal a positive shift in the Ni^(II/I) couple for the [Ni(N_(2)S_(2))_(x)Au_(y)] complexes as compared to the NiN_(2)S_(2) precursors. The incorporation of the paramagnetic vanadyl ion, [V?O]^(2+), in N_(2)S_(2) motifs has been studied in our laboratory. Previous studies of M(N_(2)S_(2)) complexes where M is Ni^(2+), ZnCl^(+), and Fe(NO) with the W(CO)_(x) reporter unit have been explored to determine the donor ability of these metallodithiolate ligands. According to their response or binding to a tungsten carbonyl unit, we have found that the sulfurs of the dianionic [(V?O)(ema)]^(2-) are activated as nuclephilies. To further investigate the donor ability of the neutral vanadyl-bound thiolate sulfurs, the oxidized {Fe(NO)_(2)}^(9) unit was used. Cleavage of the (?-I)_(2)[Fe(NO)_(2)]_(2) dimer (in the {Fe(NO)_(2)}^(9) form) was achieved with two metalloligands, Ni(bme-daco) and (V?O)bme-daco, and also N-heterocyclic carbene, IMes. Using infrared spectroscopy, the ?(NO) stretching frequencies of the LFe(NO)_(2)I (L = Ni(bme-daco), (V?O)bme-daco, and IMes) complexes were used to report the donor ability of the ligands. Cyclic voltammetry for the LFe(NO)_(2)I complexes show a more accessible {Fe(NO)_(2)}^(9/10) couple for stronger donors. Electron paramagnetic resonance (EPR) measurements of the LFe(NO)_(2)I complexes demonstrate super-hyperfine coupling of the ^(127)I to the unpaired electron on iron, and complex equilibria that indicates dissociation of the metallodithiolate ligand from the dinitrosyl iron unit.
Metallodithiolate ligands play an important role in providing the appropriate electronic environment for the catalytic function of various metalloenzymes; acetyl coA synthase serves as paradigm. Using tetradentate N_(2)S_(2) ligands to bind transition metals, a library of well-characterized synthetic analogues has been established. These metal-bound cis-dithiolates, display a wide range of reactivity, including S-based metallation, oxygenation, and alkylation.
Sulfur's affinity for gold(I) is well known and typically follows Pearson's HSAB theory. With this in mind, the NiN_(2)S_(2) moieties were used to synthesize propeller-type nickel-gold complexes within a group of [Ni(N_(2)S_(2))_(x)Au_(y)] ( x = 1 or 2; y = 1, 2, or 4) complexes. The solid-state molecular structures of these square planar cis-dithiolate nickel complexes to which gold(I) is bound contain within them classical aurophilic interactions. Electrochemical studies reveal a positive shift in the Ni^(II/I) couple for the [Ni(N_(2)S_(2))_(x)Au_(y)] complexes as compared to the NiN_(2)S_(2) precursors.
The incorporation of the paramagnetic vanadyl ion, [V?O]^(2+), in N_(2)S_(2) motifs has been studied in our laboratory. Previous studies of M(N_(2)S_(2)) complexes where M is Ni^(2+), ZnCl^(+), and Fe(NO) with the W(CO)_(x) reporter unit have been explored to determine the donor ability of these metallodithiolate ligands.
According to their response or binding to a tungsten carbonyl unit, we have found that the sulfurs of the dianionic [(V?O)(ema)]^(2-) are activated as nuclephilies. To further investigate the donor ability of the neutral vanadyl-bound thiolate sulfurs, the oxidized {Fe(NO)_(2)}^(9) unit was used.
Cleavage of the (?-I)_(2)[Fe(NO)_(2)]_(2) dimer (in the {Fe(NO)_(2)}^(9) form) was achieved with two metalloligands, Ni(bme-daco) and (V?O)bme-daco, and also N-heterocyclic carbene, IMes. Using infrared spectroscopy, the ?(NO) stretching frequencies of the LFe(NO)_(2)I (L = Ni(bme-daco), (V?O)bme-daco, and IMes) complexes were used to report the donor ability of the ligands. Cyclic voltammetry for the LFe(NO)_(2)I complexes show a more accessible {Fe(NO)_(2)}^(9/10) couple for stronger donors. Electron paramagnetic resonance (EPR) measurements of the LFe(NO)_(2)I complexes demonstrate super-hyperfine coupling of the ^(127)I to the unpaired electron on iron, and complex equilibria that indicates dissociation of the metallodithiolate ligand from the dinitrosyl iron unit.
