Indium Complexes Research Articles

One-pot total syntheses of natural products containing a THP-ring backbone: (±)-centrolobine and (±)-civet cat secretion

A one-pot strategy is devised and applied to the total syntheses of natural products with a THP-ring backbone. A special feature of this one-pot synthesis is the recyclability of the indium complex byproduct generated from the indium-mediated allylation reaction for concurrent catalysis in subsequent steps. Centrolobine and civet cat secretion are synthesized via this new method in overall yields of 58% and 23%, respectively.

H-bonding of complex indium thiocyanates with crown ether molecules

Supramolecular ensembles [In(H2O)4(NCS)2][In(H2O)2(NCS)4] · 2(18C6) (I) and [In(H2O)3(NCS)3] · 18C6 (II) are synthesized and identified by the data of elemental analyses, IR spectra, and X-ray structure analysis for structure I and X-ray phase analysis for structure II. In spite of specific features of the H-bonding of the 18C6 molecules with the cationic, molecular, or anionic indium complexes, chain motives are observed in structures I and II.

Diorgano-gallium and -indium complexes with salen ligands: Synthesis, characterization, crystal structure and C–C coupling reactions

Abstract The reactions of triorgano-gallium and -indium etherate with salen ligands in benzene afforded complexes of the type [R2MOC6H4CR′ NCH2–]2, (R/M/R′ = Me/Ga/H (1), Et/Ga/H (2), Me/In/H (3), Et/Ga/Me (4)) in nearly quantitative yields. These complexes have been characterized by elemental analysis, IR, UV–Vis, NMR (1H and 13C{1H}) and mass spectral data. The organogallium complexes showed photoluminescence in blue-green region. The complex, [(Me2Ga)2(O–(C6H4)CH N–CH2–)2] on recrystallization from benzene–hexane and dichloromethane gave orthorhombic and monoclinic forms, respectively. Both the forms are dimeric with gallium atoms acquiring a distorted tetrahedral configuration defined by two methyl groups, phenolate oxygen and azomethene nitrogen. The complexes [(Me2Ga)2(O–(C6H4)CH N–CH2–)2] and [(Me2In)2(O–(C6H4)CH N–CH2–)2] have been employed as alkylating agent for C–C coupling reaction of 1-bromonaphthalene in presence of PdCl2(PPh3)2.

Dihalogen–halogenomethyl complexes of indium(III) X2InCH2X (X=Br, I): Simultaneous coordination of soft and hard ligands

The reaction of halogenomethyl–dihalogen–indium(III) compounds X 2 InCH 2 X (X = Br, I) with dialkylsulfides, R2S opened the facile access to dialkylsulfonium methylide complexes of InX 3 of general structure X 3 (L)InCH 2 SR 2 (L = (CH 3 ) 2 SO, (C 6 H 5 ) 3 PO). Halogenomethyl–dihalogen–indium(III) compounds X 2 InCH 2 X (X = Br, I) obtained from indium monohalides and methylene dihalides were reacted with the soft donor ligands dialkylsulfides, R 2 S (R = CH 3 , CH 2 Ph) to afford the corresponding dialkylsulfonium methylide complexes of InX 3 , X 3 InCH 2 SR 2 (X = Br, R = CH 3 , 1 ; X = I, R = CH 3 , 2 ; X= I, R = CH 2 Ph, 3 ). Compound 1 was reacted with the hard donor ligands dimethylsulfoxide or triphenylphosphine oxide to give the corresponding 1:1 adduct, Br 3 (L)InCH 2 S(CH 3 ) 2 (L = (CH 3 ) 2 SO, 4 ; L = (C 6 H 5 ) 3 PO, 5 ). Compounds 1 – 5 were fully characterized in solution by NMR spectroscopy and in the solid state by X-ray methods.

Preparation, Characterization and Antimicrobial Properties of Some Indium(III) And Thallium(I) Complexes with Active Schiff Base Ligands

Article Preparation, Characterization and Antimicrobial Properties of Some Indium(III) And Thallium(I) Complexes with Active Schiff Base Ligands was published on August 1, 2009 in the journal Main Group Metal Chemistry (volume 32, issue 4).

Synthesis, characterisation and structures of thio-, seleno- and telluro-ether complexes of indium(III) halides

The indium(III) halo-bridged octahedral dimers [InX(2)(L-L)(mu-X)(2)InX(2)(L-L)] (X = Cl: L-L = MeS(CH(2))(2)SMe, MeSe(CH(2))(2)SeMe, (n)BuSe(CH(2))(2)Se(n)Bu), the ionic trans-[InX(2)(L-L)(2)][InX(4)] (X = Cl: L-L = (i)PrS(CH(2))(2)S(i)Pr; X = Br: L-L = MeS(CH(2))(2)SMe, (i)PrS(CH(2))(2)S(i)Pr, MeSe(CH(2))(2)SeMe), cis-[InCl(2)(thiamacrocycle)][InCl(4)] (thiamacrocycle = [12]aneS(4) or [14]aneS(4)) and the neutral, octahedral [InCl(3)([9]aneS(3))] and [InCl(3){MeC(CH(2)SMe)(3)}] were obtained in good yield by the reaction of 1:1 molar ratios of InX(3) with the ligand in anhydrous CH(2)Cl(2) solution. The distorted tetrahedral [InX(3)(Me(2)Se)] (X = Cl, Br or I) and [InX(3)(Me(2)Te)] (X = Br or I) were obtained from 1:3 and 1:2 molar ratios respectively of InX(3) and Me(2)E (E = Se or Te) also in CH(2)Cl(2). The ligand-bridged, distorted tetrahedral dimers [(InCl(3))(2){micro(2)-o-C(6)H(4)(CH(2)SMe)(2)}] and [(InCl(3))(2){micro(2)-MeTe(CH(2))(3)TeMe}] are formed even from a 1:1 In:ligand ratio. Key structure types were confirmed from crystal structures of [InCl(2){RSe(CH(2))(2)SeR}(micro-Cl)(2)InCl(2){RSe(CH(2))(2)SeR(2)}] (R = Me or (n)Bu), trans-[InX(2){(i)PrS(CH(2))(2)S(i)Pr}(2)][InX(4)] (X = Cl or Br), trans-[InBr(2){MeSe(CH(2))(2)SeMe}(2)][InBr(4)], cis-[InCl(2)([14]aneS(4))][InCl(4)] and [InBr(3)(Me(2)Se)]. The bulk complexes have been characterised by IR and Raman spectroscopy and microanalyses, while (1)H, (77)Se{(1)H} and (125)Te{(1)H} NMR spectroscopy show that the compounds are extremely labile in solution and undergo rapid dynamic exchange equilibria. Comparisons are drawn between these structurally rather diverse In(III) chalcogenoether complexes and the corresponding Ga(III) species (all of which are neutral and involve distorted tetrahedral coordination). The reaction of TlCl(3) with Me(2)E (E = Se or Te) shows that chlorination of Me(2)E rather than adduct formation occurs, while no reaction occurred between TlCl(3) and Me(2)S, consistent with Tl(III) being a very poor Lewis acid.

Complexes of four-membered group 13 metal(I) N-heterocyclic carbene analogues with platinum(II) fragments

A series of fluorinated bis(aryl)platinum(II) complexes, cis-[Pt(Ar(f))2(1,5-C6H10)] (Ar(f) = p-C6HF4, p-C6(OMe)F4 or C6H2F(3-)2,4,6) were reacted with the four-membered gallium(I) or indium(I) heterocycles, [:E{[N(Ar)]2CN(C6H11)2}] (E = Ga or In, Ar = C6H3Pr(i)(2-)2,6) under various stoichiometries. These yielded either the 2:1 complexes, cis-[Pt(Ar(f))2{Ga{[N(Ar)]2CN(C6H11)2}}2], trans-[Pt(C6H2F(3-)2,4,6)2{Ga{[N(Ar)]2CN(C6H11)2}}2] and trans-[Pt(Ar(f))2{In{[N(Ar)]2CN(C6H11)2}}2], or the 3:1 complexes, trans-[Pt(Ar(f))2{In{[N(Ar)]2CN(C6H11)2}}3] (Ar(f) = p-C6HF4 or p-C6(OMe)F4), all of which were crystallographically characterised. The differing outcomes of these reactions are explained in terms of the lesser nucleophilicity and greater electrophilicity of the indium heterocycle relative to its gallium counterpart. In the solid state, and in solution, the 3:1 indium complexes exhibit strong intramolecular In...F interactions which are indicative of their heterocyclic ligands displaying rare examples of "Lewis amphoteric" behaviour. An unusual platinum(0) complex in which the indium(I) heterocycle acts as a mu3-bridging ligand, [{Pt(norbornene)}3{mu3-In{[N(Ar)]2CN(C6H11)2}}2], was also prepared and structurally authenticated.

On the Nature of Organoindium Intermediates: the Formation of Readily Isolable Difluoropropargylindium Reagents and their Regioselectivity Towards Electrophilic Substitutions

The structure and reactivity of intermediate propargylindium complexes have been investigated. Their reaction with electrophiles produced a difluoroalkyne or -allene, depending on the nature of the electrophiles. A mechanism based on the Curtin-Hammett principle was invoked to explain this phenomenon. A newly proposed mechanism on the formation of indium(III) complexes, through the intermediacy of indium(I) species, could help to explain the reaction of indium with 1,1,1-difluorobromo-2-alkynes in the presence of aldehydes.

Template and pH‐Mediated Synthesis of Tetrahedral Indium Complexes [Cs⊂{In4(L)4}]+ and [In4(HNL)4]4+: Breaking the Symmetry of N‐Centered C3 (L)3− To Give Neutral [In4(L)4

Molekulare Überraschungseier entstehen aus den tripodalen siebenzähnigen Tris(1,3-diketonaten) L3− mit zentralem N-Atom in Gegenwart von Indiumionen. Die tetraedrischen Komplexe enthalten ein Caesiumion ([Cs⊂{In4(L)4}]+, siehe Bild) oder vier Protonen. Durch Deprotonierung von [In4(HNL)4]4+ entsteht der leere Käfig [In4(L)4], in dem die Symmetrie des ursprünglich C3-symmetrischen tripodalen Liganden verringert ist.

Preparation, Characterization, and Structural Systematics of Diphosphane and Diarsane Complexes of Indium(III) Halides

The ligands o-C6H4(PMe2)2 and o-C6H4(AsMe2)2 (L-L) react with anhydrous InX3 (X = Cl, Br, or I) in a 2:1 InX3/ligand ratio to form [InX2(L-L)][InX4] containing distorted tetrahedral cations, established by X-ray crystal structures for L-L = o-C6H4(PMe2)2 (X = Br or I) and o-C6H4(AsMe2)2 (X = I). IR, Raman, and multinuclear NMR ((1)H, (31)P, (115)In) spectroscopy show that these are the only species present in solution in chlorocarbons and in the bulk solids. The products from reactions in a 1:1 or 1:2 molar ratio are more diverse and include the halide-bridged dimers [In2Cl6{o-C6H4(PMe2)2}2] and [In2X6{o-C6H4(AsMe2)2}2] (X = Cl or Br) and the distorted octahedral cation trans-[InBr2{o-C6H4(PMe2)2}2][InBr4]. The neutral complexes partially rearrange in chlorocarbon solution, with multinuclear NMR spectroscopy revealing [InX4](-) among other species. The iodo complexes trans-[InI2(L-L)2][InI4(L-L)] contain rare examples of six-coordinate anions, as authenticated by an X-ray crystal structure for L-L = o-C6H4(PMe2)2. Two species of formula [In2Cl5(L-L)2]n[InCl4]n (L-L = o-C6H4(PMe2)2 and o-C6H4(AsMe2)2) were identified crystallographically and contain polymeric cations with six-coordinate indium centers bonded to one chelating L-L and a terminal chlorine, linked by alternating single and double chlorine bridges into chains. The complicated chemistry of InX3 with these two rigid chelates is contrasted with that of the flexible diphosphane Et2P(CH2)2PEt2, which forms [In2Cl6{Et2P(CH2)2PEt2}2], and with more sterically demanding o-C6H4(PPh2)2 (Sigl et al. Eur. J. Inorg. Chem. 1998, 203-210). The results also contrasted with those found for GaX3 with the same ligands (Cheng et al. Inorg. Chem. 2007, 46, 7215-7223).

Highly Fluorescent Group 13 Metal Complexes With Cyclic, Aromatic Hydroxamic Acid Ligands

The neutral complexes of two ligands based on the 1-oxo-2-hydroxy-isoquinoline motif with group 13 metals (Al, Ga, In) show bright blue-violet luminescence in organic solvents. The corresponding transition can be attributed to ligand-centered singlet emission, characterized by a small Stokes shifts of only a few nanometers combined with lifetimes in the range between 1 and 3 ns. The fluorescence efficiency is high, with quantum yields of up to 37% in benzene solution. The crystal structure of one of the indium(III) complexes (trigonal space group R3, a = b = 13.0384(15) A, c = 32.870(8) A, alpha = beta = 90 degrees , gamma = 120 degrees , V = 4839.3(14) A (3), Z = 6) shows a six-coordinate geometry around the indium center, which is close to trigonal-prismatic, with a twist angle between the two trigonal faces of 20.7 degrees . Time-dependent density functional theory calculations (Al and Ga, B3LYP/6-31G(d); In, B3LYP/LANL2DZ) of the fac and mer isomers with one of the two ligands indicate that there is no clear preference for either one of the isomeric forms of the metal complexes. In addition, the metal centers do not have a significant influence on the electronic structure nor, as a consequence, on the predominant intraligand optical transitions.

Neutral and Cationic Trimethylsilylmethyl Complexes of Indium

The trimethylsilylmethyl indium complex [In(CH2SiMe3)3] (1) was studied by single-crystal X-ray structure analysis at low temperature and shown to be weakly associated as dimeric units with a long indium−carbon bond in the bridges. The bis(trimethylsilylmethyl) cation [In(CH2SiMe3)2(THF)3][B(C6F5)4] (2) was prepared by protonolysis of the neutral complex [In(CH2SiMe3)3] with [NPhMe2H][B(C6F5)4] in THF. Crystal structure analysis revealed that mononuclear 2 adopts a square-pyramidal geometry.

Novel Chemically Modified Analogues of Neuropeptide Y for Tumor Targeting

The successful use of peptides as potential radiopharmaceuticals essentially requires the modification of the bioactive peptide hormones to introduce chelators for radiolabeling. In this study, four Y 1/Y 2 receptor-selective NPY analogues with different receptor subtype specificities have been investigated. For in vitro studies, the cold metal surrogate was used. Gallium and indium complexes were introduced by using 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid as bifunctional chelator. The peptides were synthesized by solid-phase peptide synthesis (SPPS), the chelator was coupled either at the N-terminus or at the N(epsilon) side chain of Lys(4) of the resin-bound peptide, and the labeling was performed in solution after cleavage. Competitive binding assays showed high binding affinity of the receptor-selective analogues at NPY receptor expressing cells. To test internalization of the novel peptide analogues and the metabolic stability in human blood plasma, the corresponding 5(6)-carboxyfluorescein (CF) analogues were prepared and investigated. One of the most promising analogues, the Y 1-receptor selective [Lys(DOTA)(4), Phe(7), Pro(34)]NPY was labeled with (111)In and injected into nude mice that bear MCF-7 breast cancer xenografts, and biodistribution studies were performed. In vitro and in vivo studies suggest that receptor-selective analogues of NPY have promising characteristics for future applications in nuclear medicine for breast tumor diagnosis and therapy.

The Thermodynamic Characteristics of Sublimation of Aluminum and Indium Complexes with Tetraphenylporphin according to the High-Temperature Mass Spectrometry Data

The thermodynamic characteristics of vaporization of meso-tetraphenylporphin complexes (X)MTPP (M = Al, In; X = Cl, OH; TPP is the meso-tetraphenylporphin H2TPP dianion) were studied by the Knudsen effusion method with mass spectrometric control of vapor composition. Chloride complexes sublimed as monomers over the temperature range 480–590 K. The hydroxo complex of aluminotetraphenylporphin was transferred into the gas phase in the form of the μ-oxo dimer. The temperature dependences of saturated vapor pressure were used to determine the enthalpies of sublimation of metalloporphyrins, which were found to be 203 ± 3.5 and 207 ± 6 kJ/mol for the chloride complexes of In and Al, respectively, and 206 ± 8 and 406 ± 40 kJ/mol for the monomer and μ-oxo dimer of (hydroxy)aluminum(III)porphyrin, respectively. The thermodynamic parameters of vaporization and the melting point of (OH)AlTPP were also determined (ΔvapH° = 116 ± 6 kJ/mol, ΔapS° = 72 ± 11 J/(mol K), and Tm = 579 K). Composition-thermodynamic property correlations were analyzed for metalloporphyrins.

Group 13 metal(i) and (ii) guanidinate complexes: effect of ligand backbone on metal oxidation state and coordination sphere

Reactions of lithium salts of the bulky guanidinate and phosphaguanidinate ligands, [ArNC(ER2)NAr]− (ER2 = NPri2 (Priso−), cis-NC5H8Me2-2,6 (Pipiso−) or P(C6H11)2 (PGiso−); Ar = C6H3Pri2-2,6), with group 13 metal(I) halides have been carried out. All reactions with TlBr led to monomeric thallium(I) complexes, [Tl{ArNC(ER2)NAr}], in which the ligand chelates the metal in an N,arene-fashion. The reactions with InCl led to mixed results and the isolation of the dimeric indium(II) complexes, [{InCl(Priso)}2] and [{InCl(Pipiso)}2], and the monomeric indium(I) species, [In(Pipiso)] and [In(PGiso)]. The ligands of the latter two complexes exhibit differing coordination modes in the solid state, namely N,N′-chelating and N,arene-chelating, respectively. The reactions with “GaI” were less successful and gave only low yields of the poorly characterised gallium(II) complexes, [{GaI(Priso)}2] and [{GaI(Pipiso)}2]. This study has shown that the related ligand, [ArNC{N(C6H11)2}NAr]− (Giso−) is superior for the stabilisation of group 13 metal(I) complexes. The oxidative additions of I2 or SiMe3I to one such complex, [Ga(Giso)], yielded the gallium(III) compounds, [GaI2(Giso)] and [GaI(SiMe3)(Giso)].

Enantioselective Allylation Catalyzed by Indium Complexes

Enantioselective Allylation Catalyzed by Indium Complexes

Synthesis, Characterization, and Photophysical Properties of Luminescent Gallium and Indium Complexes Constructed using Tridentate 6-Azolyl-2,2′-bipyridine Chelates

Three systematically functionalized 6-azolyl-2,2′-bipyridine ligands were prepared from reactions initiated by 6-cyano-2,2′-bipyridine. These ligands readily reacted with the metal alkyl reagents GaMe3 and InMe3 to afford the pentacoordinate complexes [(fpzbpy)MMe2] (1a, M = Ga; 1b, M = In), [(ftzbpy)MMe2] (2a, M = Ga; 2b, M = In), and [(N4bpy)MMe2] (3a, M = Ga; 3b, M = In), in which (fpzbpy)H, (ftzbpy)H, and (N4bpy)H denote 6-pyrazolyl-, 6-triazolyl-, and 6-tetrazolyl-substituted 2,2′-bipyridine, respectively. These complexes exhibited moderate blue-green emission ranging from 412 to 493 nm. On the other hand, treatment of the bidentate 2-pyridyl tetrazole ligand (pyN4)H with InMe3 afforded the bridged dimer [Me2In(pyN4)]2 (4). Calculation based on time-dependent density function theory (TDDFT) showed that the S1 state of complexes 1−3 is mainly attributed to an allowed intraligand π → π* electronic transition located at tridentate chelating moieties, together with a small contribution (<10%) of gallium (or indium) → π* (ligand) charge transfer transition. Accordingly, the corresponding emission properties of 1a−3a (or 1b−3b) can be rationalized using the correlation between the substituent effect of azolyl groups and the relative HOMO/LUMO energy level.

Enantioselective Allylation of Ketones Catalyzed by N,N′‐Dioxide and Indium(III) Complex.

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Gallium(III) and indium(III) dithiolate complexes: Versatile precursors for metal sulfides

The chemistry of classical and organometallic complexes of gallium and indium with dithiolate ligands, i.e., dithiocarboxylates, xanthates, dithiocarbamates, dithiophosphates, dithiophophinates and dithioarsenates, has been reviewed. Synthesis, spectroscopic and structural aspects of these complexes are described. Their emerging role as single source molecular precursors for the preparation of metal sulfide thin films and nano-particles has been discussed.

Germanates of 1D Chains, 2D Layers, and 3D Frameworks Built from Ge–O Clusters by Using Metal‐Complex Templates: Host–Guest Symmetry and Chirality Transfer

The self-assembly of Ge-O polyhedra by metal-complex templates leads to initial examples of open germanate structures under mild solvothermal conditions. These materials are constructed from Ge-O cluster building blocks (Ge7X19 (X = O, OH, or F) or Ni@Ge14O24(OH)3) and span the full range of dimensionalities from 1D chains of Ge7O13(OH)2F3 x Cl x 2 [Ni(dien)2] (FJ-6) to 2D layers of Ge7O14F3 x 0.5 [In(dien)2] x 0.5 H3dien x 2 H2O (1) and 3D frameworks of Ni@ Ge14O24(OH)3 x 2 [Ni(L)3] (FJ-1 a/FJ-1 b) (dien = diethylenetriamine, L = ethylenediamine (en) or 1,2-diaminopropane (enMe)). The Ge7X19 cluster in FJ-6 and 1 is formed by condensation of four GeX4 tetrahedra, two GeX5 trigonal bipyramids, and one GeX6 octahedron with a mu3-O atom at the center of the cluster, whereas the Ni@ Ge14O24(OH)3 cluster in FJ-1 a/FJ-1 b is formed by condensation of nine peripheral GeO4 tetrahedra and five interior GeO3Ni units with one mu5-Ni atom at the center of the cluster. FJ-6 is characterized by a pair of racemic Ge7O14(OH)2F3 cluster chains and represents only one example of 1D germanates; 1 exhibits unique germanate layers with uniform 10-membered-ring apertures encapsulating an unknown indium complex, and the framework structure of FJ-1 a/FJ-1 b with large 24-membered-ring channels is the first example of porous materials that contain metal-metal bonds (Ge2+-Ni+). These initial examples of germanates from metal-complex templates provide a useful model system for understanding the mechanisms of host-guest interactions, which may further facilitate the design and development of new porous materials "on demand". It is shown that the symmetry and configuration of the guest metal complex can be imprinted onto the host inorganic framework through hydrogen bonding between host and guest.