Molecular and electronic structures of new iron complexes containing N,S-coordinated o-iminothionebenzosemiquinonate(1-) π radical ligands: An experimental and density functional theoretical study

Electron-Triggered Imine Coupling: Synthesis and Characterization of Three Redox States (0,-1,-2) of a Ni(N2 S2 ) Complex

Metal imine-thiolate complexes, M(NS)2 are known to undergo imine C-C bond formation to give M(N2 S2 ) complexes (M=Co, Ni) containing a redox-active ligand. Although these transfor-mations are not typically quantitative, we demonstrate here that the one-electron reduction of a related Ni bis(imine-thiolate) complex affords the corresponding paramagnetic [Ni(N2 S2 )]- anion (2⋅- ) exclusively; subsequent oxidation with [Cp2 Fe]BF4 then affords a high yield of neutral 2 (Cp=η5 -cyclopentadienyl). Moreover, electrochemical studies indicate that a second one-electron reduction affords the diamagnetic dianion. Both anionic products were isolated and characterized by SC-XRD and their electronic structures were investigated by UV-vis spectro-electrochemistry, EPR and NMR spectroscopy, and DFT studies. These studies show that reduction proceeds primarily on the ligand, with (N2 S2 )4- containing both thiolate and ring-delocalized anions.

Influence of the electronic effect of an ancillary ligand on MMCT and LMCT in localized cyanide-bridged complexes containing non-innocent ligands

For bimetallic MV complexes with non-innocent ligands, the MMCT energy in the localized system decreases significantly while the LMCT energy in the delocalized moiety increases slightly as the electronic effect of ancillary ligands is enhanced.

Synthesis, structure and reactivity with phosphines of Hg(II) ortho-cyano-aminothiophenolate complexes formed via C-S bond cleavage and dehydrogenation of 2-aminobenzothiazoles

Addition of 2-aminobenzothiazole (abt) and substituted derivatives to Hg(OAc)2 leads to the high yield formation of ortho-cyano-aminothiophenolate (ocap) complexes [Hg{SC6H3XN(C≡N)}]n (X = H, Me, Cl, Br, NO2) resulting from dehydrogenation...

Proton-Coupled Electron-Transfer Reactivity Controls Iron versus Sulfur Oxidation in Nonheme Iron-Thiolate Complexes

Reaction of the five-coordinate Fe^II(N₄S) complexes, [Fe^II(iPr₃TACN)(abt^X)](OTf) (abt = aminobenzenethiolate, X = H, CF₃), with a one-electron oxidant and an appropriate base leads to net H atom loss, generating new Fe^III(iminobenzenethiolate) complexes that were characterized by single-crystal X-ray diffraction (XRD), as well as UV-vis, EPR, and Mössbauer spectroscopies. The spectroscopic data indicate that the iminobenzenethiolate complexes have S = 3/2 ground states. In the absence of a base, oxidation of the Fe^II(abt) complexes leads to disulfide formation instead of oxidation at the metal center. Bracketing studies with separated proton-coupled electron-transfer (PCET) reagents show that the Fe^II(aminobenzenethiolate) and Fe^III(iminobenzenethiolate) forms are readily interconvertible by H⁺/e^- transfer and provide a measure of the bond dissociation free energy (BDFE) for the coordinated N-H bond between 64 and 69 kcal mol^-1. This work shows that coordination to the iron center causes a dramatic weakening of the N-H bond and that Fe- versus S-oxidation in a nonheme iron complex can be controlled by the protonation state of an ancillary amino donor.

Synthesis and Reactivity of Iron Complexes with a Biomimetic SCS Pincer Ligand

Recent experimental evidence suggests that the FeMoco of nitrogenase undergoes structural rearrangement during N₂ reduction, which may result in the generation of coordinatively unsaturated iron sites with two sulfur donors and a carbon donor. In an effort to synthesize and study small-molecule model complexes with a one-carbon/two-sulfur coordination environment, we have designed two new SCS pincer ligands containing a central NHC donor accompanied by thioether- or thiolate-functionalized aryl groups. Metalation of the thioether ligand with Fe(OTf)₂ gives 6-coordinate complexes in which the SCS ligand binds meridionally. In contrast, metalation of the thiolate ligand with Fe(HMDS)₂ gives a four-coordinate pseudotetrahedral amide complex in which the ligand binds facially, illustrating the potential structural flexibility of these ligands. Reaction of the amide complex with a bulky monothiol gives a four-coordinate complex with a one-carbon/three-sulfur coordination environment that resembles the resting state of nitrogenase. Reaction of the amide complex with phenylhydrazine gives a product with a rare κ¹-bound phenylhydrazido group which undergoes N-N cleavage to give a phenylamido complex.

Hydrazine functionalized probes for chromogenic and fluorescent ratiometric sensing of pH and F−: experimental and DFT studies

Two novel hydrazine based sensors, BPPIH (N¹,N³-bis(perfluorophenyl)isophthalohydrazide) and BPBIH (N^1′,N^3′-bis(perfluorobenzylidene)isophthalohydrazide), are presented here.

Formation of ortho-cyano-aminothiophenolate ligands with versatile binding modes via facile carbon-sulfur bond cleavage of 2-aminobenzothiazoles at mercury(II) centres

Addition of 2-aminobenzothiazole and substituted derivatives to mercuric acetate in warm ethanol leads to the high yield formation of [Hg{SC6H3XN(C[triple bond, length as m-dash]N)}]n resulting from loss of hydrogen and sulfur-carbon bond cleavage. Addition of phosphines affords a series of complexes in which the new ortho-cyano-aminothiophenolate ligands adopt three different binding modes.

Binuclear ruthenium η6-arene complexes with tetradentate N,S-ligands containing the ortho-aminothiophenol motif

A series of cationic binuclear (η(6)-cymene-Ru)2 complexes with N2S2-ligands were synthesized in 64% to 85% yield by reaction of [Ru(η(6)-cymene)Cl2]2 with bis-S,S'-(ortho-aminothiophenol)-xylenes as BF4(-) and PF6(-) salts. The compounds were studied using NMR, HRMS, UV-vis and IR spectroscopy, EA and inductively coupled plasma (ICP) MS. It was determined that the hinged binuclear Ru complexes were anti and syn diastereomers obtained in 2 : 1 ratio for ortho- and meta-xylylene bridged ligands and in a 1 : 1 ratio for the para-xylylene bridged ligand. An anion effect was found for the presence of NaBF4 with the meta-xylylene bridged system yielding the targeted binuclear Ru complex and a mononuclear Ru complex. This mononuclear S,S'-coordinated η(6)-cymene Ru chloride structure lacked amine-metal coordination and was obtained in a 1 : 3 ratio of anti : syn diastereomers which were insoluble in CH2Cl2 and soluble in DMSO and DMF. X-ray crystallographic analysis was obtained for the N2S2 ligand, 1,2-bis{(2-aminophenyl)thiomethyl}benzene, showing a CS symmetry with amine groups facing outwards with a tilt of 28.95° from the ortho-aminothiophenol pendant ring. The interatomic sulfur-sulfur distance (S-S') is 4.6405 Å within the crystal structure while accommodating a potential metal bite angle from 1.0 Å to 5.9 Å when allowing rotation of the methylene phenyl bond.