Indium Complexes Research Articles

Facile-chelating amine-assisted synthesis of β-In2S3 nanostructures from a new single-source precursor derived from S-methyl dithiocarbazate

Flake-built 3D β-In2S3 nanostructures were synthesized by thermolysis of S-methyl dithiocarbazate–indium(III) complex precursor in hexamethylenediamine (HMDA). XRD patterns showed that the cubic phase of 3D β-In2S3 remained unchanged but the crystallinity was increased after annealing at 400 °C for 20 min. The products were also characterized by SEM, TEM, and EDS. Based on the experimental results, we propose that the growth of 3D nanostructures is controlled by the stability of the intermediate chelate complex made by indium(III) and solvent. The optical properties of the 3D β-In2S3 nanostructures were also investigated by UV–Vis and PL spectroscopy, which indicated strong quantum confinement effect.

Electronic structure of polymeric [formula omitted]-cyclopentadienyl–indium complexes

The electronic structures of oligomeric and polymeric μ -cyclopentadienyl (Cp)–indium complexes were examined by tight-binding band calculations. On the basis of the band structures, we discuss the delocalization of electrons along the axis of the polymer chain. In order to discuss the application of this polymeric complex to nano/molecular electronic devices, it is important to consider its interaction with a metal electrode. Therefore, we also examined the electronic structures of an oligomeric Cp–In complex adsorbed on a metal slab (Pt or Au).

Indium(I)-Catalyzed Allylation and Crotylation of Imines

The authors report indium-catalyzed allylation, chloroallylation, and crotylation of hydrazones. Although asymmetric allylations are well established, this work is an improvement in addition to less reactive imines. While indium(III) is often used as a Lewis acid, the utilization of indium(I) complexes in catalytic amounts is less common. This well-behaved reaction affords homo­allylic hydrazines in great yields and reportedly higher enantioselectivity than previously observed.

Ensembles of the gallium, indium, and scandium complexes with the macrocycles

Specific features of coordination chemistry of three-charge cations were considered for the formation of ensembles of crown ether 1,4,7,10,13,16-hexaoxocyclooctadecane (18C6) or its complexes M[18C6]+ (M = Na, K) with the gallium, indium, and scandium chloride and thiocyanate complexes. These features were geometric isomerism, disproportionation of molecular forms to ionic ones, and the influence of solvate molecules on the structural features of the supramolecular ensembles. The conditions for the recognition and stabilization of the complexes and the formation of heterometallic polymers were revealed.

Catalytic Asymmetric Synthesis of Substituted 3‐Hydroxy‐2‐Oxindoles

No more double trouble: The competing double-addition pathway was suppressed when chiral scandium(III) and indium(III) complexes were used to catalyze the addition of indoles and other π nucleophiles to N-alkylated and unprotected isatins (see picture). The resulting biologically relevant substituted 3-hydroxy-2-oxindoles were obtained in high yield with high enantioselectivity. Tf=trifluoromethanesulfonyl.

Chemical speciation of oxalato complexes of indium(III)

Chemical speciation of binary complexes of indium(III) with oxalic acid has been investigated pH metrically at 303 K and at an ionic strength of 0.2 mol dm−3. The approximate formation constants have been calculated with the computer program SCPHD utilizing the experimental data obtained by monitoring H+ ion concentration. The formation constants thus obtained are refined with the computer program, MINIQUAD75 using primary alkalimetric data. The selection of the best-fit chemical model is based on the statistical parameters and residual analysis. The major complexes formed are In(C2O4)2−, In(C2O4)33−, [In(C2O4)2OH]2− and [In(C2O4)2 (OH)2]3−. The distribution patterns of the different species with the pH values showed that In(C2O4)2− is the predominant species.

Indium(iii) complexes with o-iminobenzoquinone in different redox states

The indium(III) complexes containing 4,6-di-tert-butyl-N-(2,6-di-iso-propyl-phenyl)-o-iminobenzoquinone (imQ) in dianion o-amidophenolate (AP) (1) or radical-anion o-iminobenzosemiquinolate (imSQ) (3) form and iodide ligands (one in the case of 1 or two in the case of 3) have been obtained in the presence of donor agent (tetramethylethylenediamine (TMED)). The 4,6-di-tert-butyl-N-(2,6-di-iso-propyl-phenyl)-o-amidophenolate-ethyl-indium(III) (2) was obtained by the exchange reaction of disodium o-amidophenolate (APNa2) with I2InEt. Structures of complexes 1, 2 and 3 were determined by X-ray diffraction analysis.

Trinuclear pyridyl functionalised hydroxylaminato complexes of aluminium, gallium and indium

The reaction of the donor functionalised N,N-bis[2-(pyrid-2-yl)ethyl]hydroxylamine [HON(C2H4-o-py)2] and three equivalents of the Lewis-acids AlMe3, GaMe3 or InMe3 resulted in the formation of dimethylhydroxylaminato-metal complexes of the general constitution [MMe2ON(C2H4-o-py)2 x 2 MMe3] with M = Al (1), Ga (2) or In (3) by methane elimination. An alternative method to generate complexes 1 and 2 is the transmetalation of [YCp2ON(C2H4-o-py)2] with an excess of AlMe3 or GaMe3, respectively. All compounds were characterised by elemental analysis, NMR spectroscopy and single-crystal X-ray diffraction. The complexes [GaMe2ON(C2H4-o-py)2 x 2 GaMe3] (2) and [InMe2ON(C2H4-o-py)2 x 2 InMe3] (3) show highly dynamic behaviour in solution with the two pyridine nitrogen atoms changing their coordination to the metal atoms rapidly at ambient temperature. VT 1H NMR experiments showed that this dynamic exchange can be frozen on the NMR time scale. In contrast to 2 and 3, complex 1 does not change its coordination mode at ambient temperature in non-coordinating solvents.

Synthesis, characterization and biological evaluation of In(iii) complexes anchored by DOTA-like chelators bearing a quinazoline moiety

Following previous studies with a DOTA-like bifunctional chelator (H(3)L1) containing an ethylenic linker between the macrocycle backbone and a quinazoline pharmacophore, we synthesized and fully characterized a congener macrocyclic ligand (H(3)L2) having a longer, five-carbon spacer for the linkage of the quinazoline moiety. Both H(3)L1 and H(3)L2 were used to prepare indium(III) complexes aiming at their evaluation as radioactive probes for in vivo targeting of EGFR-TK. The protonation constants (log K(Hi)) of H(3)L2 were determined by potentiometry and UV-Vis spectrophotometry and the values found are 12.18, 9.74, 4.99, 3.91 and 2.53. The stability and protonation constants of InL (L = L1, L2) were also obtained from a combined potentiometry and UV-VIS spectrophotometry study. The reaction of InCl(3) with H(3)L1 and H(3)L2 led to the formation of the well-defined complexes InL1 and InL2, containing In(iii) ions coordinated by a seven (N(4),O(3)) donor atom set. These new complexes were fully characterized by spectroscopic methods (IR, NMR, ESI-MS), HPLC and by X-ray diffraction analysis in the case of InL1. The radioactive congener (111)InL2 was prepared from the reaction of (111)In-chloride with H(3)L2, in high yield and high radiochemical purity. (111)InL2 is a neutral complex that presents a hydrophilic character and exhibits a high in vitro and in vivo stability. H(3)L2 and InL2 do not inhibit the cell growth of A431 cervical carcinoma cells. In this EGFR-expressing cell line, (111)InL2 has shown very low cell internalization. These findings indicate that these DOTA-like chelators are not the best suited bifunctional ligands to obtain In(iii) complexes with adequate biological properties for targeting the EGFR-TK.

Stepwise assembly of a bis-hydroxylaminato gallium–indium complex

A heterobimetallic gallium-indium complex with five-coordinate InMe group bonded via two O and two N atoms to a [GaR(2)ON(Me)(CH(2))(2)N(Me)O](2) macrocycle resulted from the reaction of the OH- and NH-functional bishydroxylaminato complex of gallium, MeN(OH)(CH(2))(2)N(H)(Me)OGaR(2)O-cyclo[N(Me)(CH(2))(2)N(Me)OGaR(2)] (R = (t)Bu) with InMe(3), whereas the reaction of the latter with Me(3)N x AlH(3) affords a gallium hydride with Ga-Ga bonds.

Alternative syntheses of univalent indium salts including a direct route from indium metal

Protonolysis of indium(I) reagents using an [18]crown-6 poly-ether pre-treated with trifluoromethanesulfonic acid (HOTf) provides an efficient route to the known salt [In([18]crown-6)][OTf] in excellent yield. The analogous reaction employing trifluoroacetic acid (HTFA) allows for the isolation of [In([18]crown-6)][TFA], a monovalent indium complex for which the uncrowned salt is not stable at ambient conditions. The direct treatment of indium metal with HOTf, either in the presence or absence of [18]crown-6, provides a high-yield synthetic approach to univalent indium salts that does not require the use of a pre-existing indium(I) reagent.

Chiral Indium Alkoxide Complexes as Initiators for the Stereoselective Ring-Opening Polymerization of rac-Lactide

The indium complex InL(2)N'' has been prepared from the reaction of 2 equiv of ((t)Bu)(2)P(O)CH(2)CH((t)Bu)OH (HL) with InN''(3) (N'' = N(SiMe(3))(2)). This complex reacts with a further equivalent of 2,6-di-tert-butylphenol or HL to afford the adducts InL(2)(OAr) and InL(3), respectively. Confirmation that the anion L(-) exhibits "ligand self-recognition" in the formation of predominantly homochiral complexes RR-InL(2)N'' and SS-InL(2)N'' is obtained from (1)H and (31)P NMR spectroscopic data. However, the self-recognition is less effective at the indium cation, and mixtures of InL(3) complexes with different configurations are observed. Single-crystal X-ray diffraction data confirm the five-coordinate, distorted bipyramidal In center in InL(2)N'' and InL(2)(OAr) as anticipated. Selected crystals of InL(3) show two of the possible configurations: one is the fac-RRR-InL(3) complex, analogous to the lanthanide complexes LnL(3) reported previously (Ln = Y, Eu, Er, Yb); another is the alternative, homochiral mer form RRR'-InL(3). All three complexes are efficient single-component initiators for the ring-opening polymerization of rac-lactide over a wide range of temperatures and monomer-to-initiator ratios, exhibiting reasonable control over the synthesis of isotactic polylactide. Despite its poorly defined structure, InL(3) is the fastest initiator among the three complexes for the polymerization of rac-lactide, and shows the best tacticity control. The polylactide samples have high molecular weights M(n,exp) (between 44 000 and 270 000 g/mol at completion) and narrow polydispersities (as low as 1.25 at completion).

Good optical limiting performance of indium and gallium phthalocyanines in a solution and co-polymer host

The optical limiting characteristics of tetra- and octasubstituted gallium and indium phthalocyanine complexes have been studied by means of the open-aperture Z-scan technique with nanosecond pulses at 532 nm. The nonlinear response demonstrated that all investigated compounds exhibited strong reverse saturable absorption for both solution and solid-state-based experiments. The results showed that the ratio of the excited to ground state absorption cross section κ and effective nonlinear absorption coefficient βeff are largely dependent on the linear absorption coefficient. All compounds in chloroform exhibited almost the same optical limiting performance at the same linear absorption coefficient. Pc/PMMA composite films display a much larger effective nonlinear absorption coefficient, lower ratio of the excited to ground state absorption cross section and lower saturation fluence for optical limiting when compared to the same Pc molecules in solution. All gallium and indium complexes of phthalocyanines are good candidates for optical limiting applications.

Synthesis and structure of novel chiral amido-imine complexes of aluminum, gallium, and indium

The reactions of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN, 1) with tri-iso-butylaluminum, triethylgallium or trimethylindium give the novel amido-imine complexes (Bui—dpp-BIAN)AlBui2 (4), (Et—dpp-BIAN)GaEt2 (5), and (Me—dpp-BIAN)InMe2 (6), respectively. The reaction of (dpp-BIAN)AlI(Et2O) (7) with allyl bromide affords analogous chiral amido-imine derivative (All—dpp-BIAN)AlBrI (8). Hydrolysis of 8 affords the amino-imino compound (All—dpp-BIAN)H (9). The new compounds 4–6, 8, and 9 have been characterized by 1H NMR and IR spectroscopy. The molecular structures of 5, 6, and 9 were determined by single crystal X-ray analysis.

Synthesis and structural studies of gallium(III) and indium(III) complexes of 2-acetylpyridine thiosemicarbazones

Four 2-acetylpyridine 4 N-alkyl thiosemicarbazones, and their Ga(III) and In(III) complexes have been prepared and characterised by fluorescence, UV–Vis, IR, 1H and 13C NMR spectroscopy, mass spectrometry and X-ray crystallographic analysis. Comparison of the crystal structures gave an insight into the nature of the complexes formed, demonstrating a preference for [ ML 2] + type complexes with gallium and [ MLX 3] species with indium. Stability studies on two candidates indicated that complex [InL 3Cl 2MeOH] was stable to chemical degradation for prolonged periods in human serum, giving this complex potential for further biological evaluation.

Indium-catalyzed enantioselective allylation of aldehydes with β-carbonyl allylstannanes: An efficient synthetic method for chiral α-methylene-γ-lactones

The catalytic enantioselective allylation of aldehydes with β-carbonyl allyltributylstannanes in the presence of chiral indium complexes gave the optically active homoallylic alcohols, which can be converted to the corresponding optically active α-methylene-γ-butyrolactones.

InIII and GaIII Complexes of Sugar‐Substituted Tripodal Trisalicylidene Imines: The First 68Ga‐Labelled Sugar Derivative

AbstractGallium and indium complexes derived from salicylaldimines of 1,1,1‐tris(aminomethyl)ethane (TAME) with pendantxylose, glucose and galactose units have been synthesised as model compounds for potential application as radiotracers. The formed neutral complexes have been characterised by NMR spectroscopy, elemental analysis, mass spectrometry and, in the case of the galactose‐bearing InIII complex, by single‐crystal X‐ray structure analysis. Octahedral coordination was observed with the appearance of an equilibrium of Λ‐ and Δ‐isomers at the metal centre. The glucose‐appended ligand was radiolabelled with 68GaIII ions in up to 98 % yield depending on the prevailing pH value. The in vitro stability of the radioactive complex was examined by challenge experiments against apo‐transferrin and blood plasma. Very high stability was observed; even after a period of 2 h, 90 % of the complex could still be detected. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Novel indium(III) complexes with sterically hindered o-iminobenzoquinone

Abstract The first examples of indium(III) derivatives based on sterically hindered 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzoquinone (imQ) were synthesized and characterized in details. The interaction of sodium o-iminobenzosemiquinolate with indium(III) iodide produces bis[4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonato]-iodo-indium(III) (1). The same product 1 was obtained by the reactions of imQ with InI or imQ disodium derivative with indium(III) iodide. The interaction of imQ with InI3 results in the formation of indium(III) compound (2) containing neutral form of o-iminobenzoquinone ligand. Structures of complexes 1 and 2 were determined by X-ray diffraction analysis.

Synthesis, crystal structure, electronic structure, bonding, photoluminescence and spectroscopic property investigations of a mononuclear 1,10-phenanthroline and 5-bromo-salicylate ternary indium(III) complex

The synthesis, X-ray structure, electronic structure, bonding, photoluminescence, spectroscopic property and characterization of an indium(III) complex, [In(Hbsac) 3(phen)] ( 1) (H 2bsac = 5-bromo-salicylic acid, and phen = 1,10-phenanthroline) are presented. Complex 1 is octacoordinate and carboxylate chelating, being novel and rarely reported for main group complexes. The electronic structure, bonding and the charge transfer properties of light excitation and light emission are discussed in detail using first-principles theory, including partial density of states (PDOSs), crystal orbital overlap population (COOP), the density functional theory (DFT/TDDFT) analysis schemes. The charge transfer is mainly π → π ∗ intraligand charge transfer transition (ILCT) for excitation, and π → π ∗ ligand-to-ligand charge transfer transition (LL′CT) for emission in nature.

Indium Complexes Supported by 1,ω-Dithiaalkanediyl-Bridged Bis(phenolato) Ligands: Synthesis, Structure, and Controlled Ring-Opening Polymerization ofl-Lactide

Indium bis(phenolato) complexes [In(L)R(THF)(n)] (L = 1,4-dithiabutanediylbis(4,6-di-tert-butylphenolato) (etbbp), R = Cl, n = 0, 1; L = 1,3-dithiapropanediylbis(6-tert-butyl-4-methylphenolato) (mtbmp), R = Me, n = 1, 2; L = 1,4-dithiabutanediyl-bis(6-tert-butyl-4-methyl-phenolato) (etbmp), R = Me, n = 0, 3; L = etbbp, R = CH(2)SiMe(3), n = 0, 4; L = 1,4-dithiabutanediylbis{4,6-di(2-phenyl-2-propyl)phenolato} (etccp), R = CH(2)SiMe(3), n = 0, 5) were prepared from indium trichloride or from the corresponding tris(alkyl) complexes and 1 equiv of tetradentate 1,omega-dithiaalkanediyl-bridged bis(phenol) LH(2). The monomeric nature of the alkyl indium complexes was shown by X-ray diffraction studies of the complexes [In(mtbmp)Me(THF)] (2), [In(etbbp)(CH(2)SiMe(3))] (4), and [In(etccp)(CH(2)SiMe(3))] (5). Pseudo-octahedral configuration was found for 2, while square pyramidal structure was observed for 4 and 5. The isopropoxy complexes [In(L)(O(i)Pr)] (L = etbbp, 6; etccp, 7) were synthesized starting with indium tris(isopropoxide). Complex 6 crystallized as homochiral dimer of pseudo-octahedral fragments with bridging mu(2)-alkoxide ligands, but in solution two diastereomers were observed. The isopropoxy complexes efficiently initiated the ring-opening polymerization of L-lactide in toluene to give isotactic poly(L-lactides) with narrow molecular weight distribution (M(w)/M(n) = 1.03-1.18).