Nagina Amir

Group 12 metal(II) complexes with 1-methylimidazoline-2(3H)-thione (mitH): correlation between crystal structure and physicochemical property

The crystal structures of [ZnX2(mitH)2] (X = Cl (1), Br (2)), [ZnI(mitH)3]I (3), and [CdX2 (mitH)2] (X = Cl (4), Br (5), I (6)) (mitH = 1-methylimizadoline-2(3H)-thione) were determined by X-ray crystallography and all complexes were characterized by IR, far-IR, Raman, and UV–Vis absorption (solid) spectroscopies. All complexes except 3, which have a different ZnIS3 coordination mode, have a distorted tetrahedral geometry with an MX2S2 coordination mode. Each π-character of the C=S bonds (from 37.7 to 45.4%) is smaller than that of free mitH (51.9%). Their M–S–C bond angles (from 97° to 109°) support that the C=S bonds are not a full double bond. Their stretching vibration frequencies of M–S (300–320 cm−1) and M–X (229–290 cm−1) in both far-IR and Raman spectra show the lower energy shifts with increasing weight of metal(II) or halide ions. Similarly, some shifts (from 275 nm for 1 to 293 nm for 6) are also observed in CT transition bands in UV-Vis absorption spectra.

Syntheses, structures, and properties of oxorhenium(V) complexes with 2-, 5-, and/or 7-substituted 8-quinolinolato ligands

Abstract Five mononuclear oxorhenium(V) complexes containing 8-quinolinolato derivatives, [ReOCl2(2-X-5-Y-7-Z-8-Oqn)(PPh3)] (qn= quinoline; PPh3=triphenylphosphine; X=Me, Y=Z=H, 1; X=Z=H, Y=Cl, 2; X=H, Y=Z=Cl, 3; X=H, Y=Cl, Z=I, 4; X=H, Y=Z=Br, 5), were newly synthesized by the reaction of [ReOCl3(PPh3)2] with the corresponding 8-hydroxyquinoline ligands. From X-ray crystal structural analyses, all the obtained complexes have the same geometry; the ReaO bond occupies the trans position to the O atom of the deprotonated 8-hydroxyquinoline ligand. The complexes, which retain their structures in solution, were characterized on the basis of IR, UV–vis, 31P NMR spectra, and cyclic voltammetry. Depending on the existence of 2-Me substituent in the ligands, some stereochemical and electrochemical differences were observed. In contrast to the case of the corresponding 2-methylquinolin-8-ylamido complex [ReOCl2(2-Me-8-HNqn)(PPh3)], substitution reaction of PPh3 to OPPh3 (Ztriphenylphosphine oxide) or pyridine did not take place, reflecting the high stability of the present 8-quinolinolato complexes.

Nickel(II) complexes with Schiff bases derived from salicylaldehyde or pentanedione and 3-aminopropanethiol

Template reactions of salicylaldehyde or pentanedione with 3-aminopropanethiol (Hapt) in the presence of Ni(II) ions are described. When salicylaldehyde was used, a dinuclear Ni(II) complex [Ni(bit′)]2 (2) (H2bit′ = 2-(3′-mercaptopropyliminomethyl)phenol) was obtained instead of the reported trinuclear one [Ni(bit)]3 (1) (H2bit = 2-(2′-mercaptoethyliminomethyl)phenol) containing 2-aminoethanethiol (Haet). Starting from pentanedione, the expected dinuclear complex [Ni(pit′)]2 (H2pit′ = 2-(3′-mercaptopropylimino)pentanol) was not obtained, nor was [Ni(pit)]2 (3) (H2pit = 2-(2′-mercaptoethylimino)pentanol). The complex was found to be a trinuclear Ni(II) complex [Ni{Ni(apt)2}2]2+ (4), as confirmed by elemental analysis, electronic and NMR spectra. Complexes 1 and 3 were also synthesized and their 13C, 1H–1H and 13C–1H NMR spectra are discussed in detail. The X-ray crystal structure of 2 shows that two Ni(II) ions are connected by the thiolate donor atom from each ligand, resulting in a four-membered ring. Differences in reactivity and properties is due to the presence of an additional methylene group in the aminoalkane arm of the ligand.

Linear-Type S-Bridged Trinuclear Complexes with RuIII Ion and Octahedral fac(S)-[M(aet)3] Units (M = RhIII, IrIII; aet = 2-Aminoethethiolate)

ABSTRACT The reactions of fac(S)-[M(aet)3] (M = RhIII, IrIII; aet = 2-aminoethanethiolate) with RuCl3 · 3H2 O in water gave trinuclear complexes, ΔΛ-, ΔΔ/ΛΛ-[Ru{Rh(aet)3}2]3+ ( 1a, 1b ) and ΔΛ-, ΔΔ/ΛΛ-[Ru{Ir(aet)3}2]3+ ( 2a, 2b ). The crystal structure of 2a (NO3)3 · 3H2 O revealed that the central RuIII ion is coordinated by six S atoms from two fac(S)-[Ir(aet)3] units in an octahedral geometry, forming a linear-type S-bridged trinuclear structure. It was found that the UV-Visible (UV-Vis) spectral patterns of all complexes depend upon the terminal fac(S)-[M(aet)3] units. In the electro- and spectroelectrochemistry of these complexes, the Ir trinuclear complex showed a reversible [Ru{Ir(aet)3}2]3+/4+ redox process.

Dichlorooxo(quinoline-8-thiolato-κ2N,S)(triphenylphosphine oxide-κO)rhenium(V) acetone solvate

The complex molecule in the title compound, [Re(C(9)H(6)NS)Cl(2)O(C(18)H(15)OP)].C(3)H(6)O, has distorted octahedral geometry. The Re=O bond occupies the position trans to the triphenylphosphine oxide O atom. The Re-Cl bond trans to the thiolate S atom is longer than that trans to the quinoline N atom, implying a stronger trans influence of the S atom. Intra- and intermolecular pi-pi interactions are also observed between the pi rings in the complex.

Bis(μ‐cyst­amine‐κ4N,S:S′,N′)­bis­[(2‐amino­ethane­thiol­ato‐κ2N,S)­iridium(III)] tetrabromide dihydrate

In the complex cation of the title compound, [Ir2(C2H6NS)2(C4H12N2S2)2]Br4.2H2O, which was obtained by rearrangement of [Re[Ir(aet)3]2]3+ (aet is 2-aminoethanethiolate) in an aqueous solution, two approximately octahedral fac(S)-[Ir(NH2CH2CH2S)3] units are linked by two coordinated disulfide bonds. The complex cation has a twofold axis, and the two non-bridging thiolate S atoms in the complex are located on opposite sides of the two disulfide bonds. Considering the absolute configurations of the two octahedral units (Delta and Lambda) and the four asymmetric disulfide S atoms (R and S), the complex consists of the Delta(RR)Delta(RR) and Lambda(SS)Lambda(SS) isomers, which combine to form the racemic compound.