Indium Centers Research Articles

Organometallic sesquialkoxides of aluminium, gallium and indium.

Organometallic sesquihalides of aluminium are important intermediates in technical processes. However, those compounds and their homologues with gallium or indium centers have not been structurally characterized so far. On the other hand organometallic sesquialkoxides have been isolated. The major synthetic routes and the structures of the corresponding products will be discussed. Furthermore, cage-contructiveness reactions having sesquialkoxides as educts will be shown. Discussion will focus primarily on the syntheses, the spectroscopic findings and a structural comparison. Especially the structural motifs deserve attention because of the structural connection to the well-known earth metal alkoxides.

New class of holographic materials based on semiconductor CdF2 crystals with bistable centers: III. Mechanisms of recording and decay of holographic gratings

The mechanisms of recording and decay of holographic gratings in CdF2 crystals with bistable gallium or indium centers are considered. The analysis of the decay kinetics allows one to determine potentialities and conditions for using these crystals both for static recording of holograms and for holography in real time. This time scale is fairly broad and covers the time range from 1 s to 10 μs or shorter. Energy characteristics of the bistable centers, namely, the binding energies of the deep and shallow levels and heights of the barriers between them, are refined.

The synthesis and structural characterisation of the first phosphavinyl–Group 13 complexes

The bisphosphavinyl indium complex, [CyIn{C( t Bu)PCy} 2], has been prepared from the reaction of two equivalents of [CyPC( t Bu)MgCl(OEt 2)] with CyInBr 2. Its crystal structure shows it to be monomeric with a trigonal planar indium centre. The reactions of [CyPC( t Bu)MgCl(OEt 2)] with MX 3, M=Al, Ga or In, X=Cl or Br, leads to facile phosphavinyl coupling reactions and the formation of the diphosphametallobicyclo[1.1.1]pentane complexes, [M{C 2( t Bu) 2P 2Cy 2}{C( t Bu)PCy}], which contain terminal phosphavinyl ligands.

The structure of the [Et 2In( μ, λ-O 2C)–C 6H 4–2–NH 2] ∞ coordination polymer: Competition of intramolecular hydrogen bonding with metal–ligand coordination preferences in determining the molecular and crystal structure

The X-ray structure analysis of [Et 2In( μ, λ-O 2C)–C 6H 4–2–NH 2] n ( 1) reveals an extended one-dimensional chain comprised of an array of five-coordinate indium centers. The chain unit repeated along two-fold screw axis is defined by the diethylindium moiety chelated asymmetrically by the carboxylate group with one of the two carboxylate oxygens acting as bridge to the next indium center in the chain. The NH 2 group does not participate in the coordination of the metal center but is involved in an intermolecular hydrogen bond.

General Synthesis of Homoleptic Indium Alkoxide Complexes and the Chemical Vapor Deposition of Indium Oxide Films

A general synthetic route to homoleptic indium alkoxide complexes was developed, and one of the new compounds was used as a precursor to transparent, conductive indium oxide films. The amide complex In[N-t-Bu(SiMe3)]3 reacted with t-BuOH, EtMe2COH, Et2MeCOH and i-PrMe2COH to yield the dimers [In(μ-OR)(OR)2]2 (R = t-Bu, CMe2Et, CMeEt2, and CMe2i-Pr) in high yield. Similar reactions of In[N-t-Bu(SiMe3)]3 with the less bulky alcohols i-PrOH and Et2HCOH yielded, respectively, insoluble [In(O-i-Pr)3]n and the tetramer In[(μ-OCHEt2)2In(OCHEt2)2]3, which has a six-coordinate central indium atom surrounded by three four-coordinate indium atoms. The compounds [In(O-i-Pr)3]n and In[(μ-OCHEt2)2In(OCHEt2)2]3 were also prepared by reacting [In(μ-O-t-Bu)(O-t-Bu)2]2 with an excess of the respective alcohols. Attempts to prepare the previously reported oxo cluster In5(μ5-O)(μ3-O-i-Pr)4(μ2-O-i-Pr)4(O-i-Pr)5 by thermally decomposing [In(O-i-Pr)3]n failed. The reaction between In[N-t-Bu(SiMe3)]3 and 2,6-diisopropylphenol afforded the bis tert-butylamine adduct In(O-2,6-i-Pr2C6H3)3(H2N-t-Bu)2. The evidence suggests that the tert-butylamine ligands in In(O-2,6-i-Pr2C6H3)3(H2N-t-Bu)2 resulted from a secondary reaction between HN-t-Bu(SiMe3) and 2,6-diisopropylphenol. The powerful donor p-(dimethylamino)pyridine (p-Me2Npy) reacted with [In(μ-O-t-Bu)(O-t-Bu)2]2 to yield 5-coordinate In(O-t-Bu)3(p-Me2Npy)2 and with the more sterically encumbered complex [In(μ-OCMeEt2)(OCMeEt2)2]2 to yield four-coordinate In(OCMeEt2)3(p-Me2Npy). In addition, [In(μ-O-t-Bu)(O-t-Bu)2]2 reacted with 2,2,6,6-tetramethyl-3,5-heptanedione (t-Bu2-β-diketone) to afford (t-BuO)2In(μ-O-t-Bu)2In(t-Bu2-β-diketonate)2, which has four- and six-coordinate indium centers and virtual C2 symmetry. X-ray crystallographic studies were carried out for [In(μ-O-t-Bu)(O-t-Bu)2]2, In[(μ-OCHEt2)2In(OCHEt2)2]3, In(O-2,6-i-Pr2C6H3)3(H2N-t-Bu)2·1/2C7H9, In(O-t-Bu)3(p-Me2Npy)2·1/2Et2O, In(OCMeEt2)3(p-Me2Npy), and (t-BuO)2In(μ-O-t-Bu)2In(t-Bu2-β-diketonate)2. The t-amoxide complex [In(OCMe2Et)3]2 and oxygen were used as precursors to deposit transparent, highly conductive indium oxide films on silicon, glass, and quartz substrates at substrate temperatures of 300−500 °C in a low-pressure chemical vapor deposition process. A backscattering spectrum indicated the film deposited at 500 °C was stoichiometric In2O3 (O/In = 1.46 ± 0.07). The films were transparent in the visible region (>75%) and had resistivities as low as 9.1 × 10-4 Ω cm. X-ray diffraction studies indicated the films deposited on glass were cubic and highly (100) oriented.

New Types of Base-Stabilized Alkyl Aluminum, Gallium, and Indium Complexes

Novel dinuclear metal complexes with the general formula [(Me2M){NC5H4 C(R)NNC6H5}(MMe3)] (M = Al, R = CH3 (1); M = Ga, R = CH3 (2); M = Al, R = H (3); M = Ga, R = H (4)) result when 2-pyridinecarboxaldehyde phenyl hydrazone ligands are mixed with trimethylaluminum and -gallium. The decagallium complex (GaMe2)8(GaMe)2(μ4-O)2(μ3-O)4(C12H10N3)2 (5) was isolated during the synthesis of 4 as a minor orange product. Three dinuclear metal compounds of the general formula [(Me2M)(SC4H3CHNNC6H5)]2 (M = Al (6); M = Ga (7); M = In (8)) were synthesized by the methane elimination reaction of thiophenecarboxaldehyde phenylhydrazone with trimethyl aluminum, -gallium, and -indium. The μ4-oxo complex [(Me2In)2(OC4H3CH NNC6H5)]2O (9) was prepared via the reaction of furancarboxaldehyde phenylhydrazone with trimethylindium. The X-ray crystal structures of 1, 4, 5, 7, and 9 are described. The structural data revealed that 5 is a decanuclear gallium compound that contains an eight-membered Ga4O4 cyclic core and that 9 is a tetranuclear indium compound with a weak interaction between the pendant furan and the indium center.

(Phosphacyclopentadienyl)indium(I) Derivatives: Synthesis and X-ray Crystal Structure of [In(η5-P3C2But2)

Co-condensation of indium vapor and tert-butylphosphaethyne at 77 K yields two new, volatile In-(1) complexes: [In(?5-P3C2But2)] (1) and [In(?5-P2C3But3)] (2). A single-crystal X-ray diffraction experiment on 1 reveals a discrete molecular structure, involving half-sandwich coordination of the P3C2But2 ring around the indium center. 1 may be independently prepared by treating InI with the newly synthesized, base-free ligand salt K(P3C2But2).

Structural characterization of an ordered crystalline modification of [In(SePh)3

A triclinic modification of [In(SePh)3]∞ has been structurally characterized by X-ray diffraction, demonstrating that it is chemically distinct from a previously reported monoclinic form. Thus, triclinic [In(SePh)3]∞ is crystallographically ordered and contains five-coordinate trigonal bipyramidal indium centers with asymmetrically bridging [SePh] ligands, whereas the monoclinic form is disordered and contains six-coordinate octahedral indium centers with symmetrically bridging [SePh] ligands.

Molecular structure of [CpFe(CO) 2 ] 3 In

The molecular structure of [CpFe(CO)2]3In (Cp=η5-C5H5) has been determined and contains a planar, three-coordinate indium center bound to three CpFe(CO)2 moieties by unsupported In–Fe bonds. The orientation of the CpFe(CO)2 units relative to the Fe3In plane precludes π-type interaction between iron and indium, while comparison with the isostructural gallium analog suggests the orientation of the CpFe(CO)2 units is controlled by the size of the central atom and the inter-ligand steric repulsion. Crystal data: monoclinic, monoclinic, C2/c, a = 26.911(5), b = 10.838(2), c = 16.474(3)A, β = 111.63(3)°, V = 4465(2)A3 and, Z = 8.

Electronic level diagram and structure of metastable centers in CdF2:Ga and CdF2:In semiconducting crystals

A study is reported of the optical properties of wide-gap, predominantly ionic cadmium fluoride crystals in photo-and thermally stimulated transformations of metastable indium and gallium centers. An analysis of these properties leads one to a conclusion of gallium having two metastable states (two types of deep centers). The deep-center binding energies and the barriers separating the shallow (hydrogenic) and deep centers have been determined for both impurities. Configuration-coordinate diagrams are developed, and microscopic models for the deep centers are proposed. It is concluded that these centers are identical with the metastable DX centers in typical semiconducting crystals. Thus cadmium fluoride is the most ionic among the crystals where DX centers have thus far been found. The potential of using such crystals for optical information recording is discussed.

TriorganoazidometalatesCompounds with Unusual Structural Motifs

The reaction of Ga(CH2Ph)3 with CsN3 in THF gives, after recrystallization from toluene, the metalate [Cs(toluene)0.5{(PhCH2)3GaN3}] (1), whereas the corresponding reaction of In(CH2Ph)3 with CsN3 in THF yields, after recrystallization from toluene, the solvent-free salt Cs[(PhCH2)3InN3] (2). 1 and 2 have been characterized by NMR, IR, and MS techniques as well as by X-ray analyses. According to the X-ray structure determination, 1 and 2 can be described as coordination polymers [1]n and [2]n in the solid state. [1]n consists of layers, packed along the crystallographic a-axis. The monomers 1 are connected by Cs···N3 and Cs···aryl contacts to form polymeric sheets. [2]n mainly consists of chains aligned along the directions [011] and [011̄]. Here, the monomers 2 are connected by Cs···phenyl contacts. In addition, weak In···N3 interactions of 2.901(5) Å are observed, leading to a strongly distorted trigonal bipyramidal coordination sphere of the indium center (angular sum, equatorial plane, 355°) and to a cross-linking of the chains in the direction [100].

Thiosemicarbazone Complexes of Indium with New Modes of Coordination: X-ray Crystal Structure of {(Me2In)2[NC5H4CMeNNC(S)NC6H5]2}(InMe)

The trinuclear complex {(Me2In)2[NC5H4CMeNNC(S)NC6H5]2}(InMe) (3) has been prepared. X-ray analysis reveals that the two indium moieties are coordinated to the three nitrogen atoms in the ligand and the one indium moiety is attached to the two nitrogen and two sulfur atoms of the two ligands. The trinuclear nature and unusual distorted-square-pyramidal coordination geometry of the indium centers for 3 were confirmed through single-crystal X-ray diffraction analyses.

Paramagnetic susceptibility of additively colored CdF2:In photochromic crystals

The paramagnetic susceptibility Kpara of CdF2:In crystals with metastable indium centers has been measured in darkness after photobleaching the crystals in visible light in the temperature interval 4–300 K. For crystals cooled in darkness to liquid-helium temperature Kpara is wholly determined by the accompanying impurity Mn2+ with magnetic moment J=5/2. Illumination of the crystals leads to the appearance of an induced signal δKpara due to the formation of centers with J=1/2. The results of the experiments indicate the absence of paramagnetism in the deep state of the indium center and its existence in the shallow (donor) state, i.e., they confirm the two-electron (negative-U) nature of the deep indium level in CdF2.

A New In4 Cluster with Short InIn Bonds in Trigonal‐Planar In(InTrip2)3

Trigonal-planar coordination is seen for the indium center in In(InTrip2)3 (1) (Trip  2,4,6-iPr3C6H2), the first indane with three unusually short bonds to indium substituents. The compound is obtained by the reduction of the diindane Trip2InInTrip2 with lithium metal. In contrast, reduction of the aluminum and gallium analogs gives the [Trip2MMTrip2]− anions, which have a MM π-bond order of 0.5.

A new synthesis of acetato porphyrinato indium(III) from indium(III) oxide and X-ray crystal structures of In(tpyp)(OAc) and In(tmpp)(OAc)

The indium porphyrin complexes [In(tpp)(OAc), In(tpyp)(OAc), In(tmpp)(OAc)] were prepared in good yields by refluxing the respective porphyrin (tpp, tpyp, tmpp) with In 2O 3 in acetic acid containing sodium acetate. The structures of In(tpyp)(OAc) and In(tmpp)(OAc) were determined by a single-crystal X-ray structure analysis. The indium atom is displaced 0.731 Å from the mean porphyrin plane (C 20N 4). The geometry around the indium centre of the In(tpyp)(OAc) molecule has In(1)-O(l) = 2.185(6), In(1)-O(2) = 2.412(6) and average In(l)-N p= 2.177(5) Å. This indicates that an asymmetric-bidentate acetato group is coordinated to the indium(III) atom in In(tpyp)(OAc). In the structure of In(tmpp)(OAc) the indium(1)-oxygen distances are In(l)-O(6) = 2.31(1) and In(1)-O(5) = 2.31(1) Å, whereas the indium(l) atom lies 0.697 and 0.758 Å from the four porphyrin nitrogens (4 N p) and the 24-atom porphyrin plane (C 20N 4), respectively. This indicates that In(1)(tmpp)(OAc) contains a symmetric bidentate binding of the acetate ligand.

Synthese und Eigenschaften von Benzylgallium(indium)-Verbindungen. Die Kristallstrukturen von [(PhCH2)2GaBr]2, [(PhCH2)2GaN(H)t-Bu]2 und [PhCH2InCl2(THF)2] / Synthesis and Properties of Benzylgallium(indium) Compounds. The Crystal Structures of [(PhCH2)2GaBr]2, [(PhCH2)2GaN(H)t-Bu]2 and [PhCH2InCl2(THF)2

(PhCH2)2GaBr (1) can be obtained by the redistribution reaction of GaBr3 with Ga(CH2Ph)3 in a molar ratio 1:2. Treatment of 1 or (PhCH2)2GaCl with one equivalent of LiN(H)t-Bu gives the diorganogallium amide [(PhCH2)2GaN(H)t-Bu]2 (2). The toluene-insoluble PhCH2InCl2 can be structurally investigated after dissolving in THF and crystallization as [PhCH2InCl2(THF)2] (3). 1 - 3 were characterized with NMR, IR and MS techniques as well as by X-ray structure determinations. 1 forms two crystallographic independent dimers while 2 is a centrosymmetric dimer in the solid state. 3 is a monomer with a trigonal-bipyramidal coordination sphere at the indium center.

Dimethylindium octahydrotriborate, Me2InB3H3: synthesis, crystal structure and spectroscopic properties of a volatile indium hydride

Reaction between trimethylindium and tetraborane(10) at room temperature yields the volatile, viscous liquid dimethylindium octahydrotriborate, the first reported example of a volatile indium hydride; spectroscopic properties of the vapour indicate a molecular structure akin to that of Me2A1B3H8 although the crystal structure implies a more ionic formulation, [Me2In]+[B3H8]–, with the coordination at each indium centre being augmented via secondary intermolecular interactions with terminal hydrogen atoms.

Synthetic and structural studies on organotransition metal-indium thiocyanate complexes

The reaction between In(NCS) 3 and two equivalents of Na[Mo(CO) 3(η-C 5H 5)] afforded the indium thiocyanate complex [In(NCS){Mo(CO) 3(η-C 5H 5)} 2] ( 2). The complexes [In(NCS){Fe(CO) 2(η-C 5H 5)} 2] ( 3) and [In(NCS){W(CO) 3(η-C 5H 5)} 2] ( 4) were prepared similarly. The reaction between 2 and OPPh 3 afforded the complex [In(NCS)(OPPh 3) {Mo(CO) 3(η-C 5H 5)} 2] ( 5) and that between 3 and 4-picoline afforded [In(NCS)(4-picoline){Fe(CO) 2(η-C 5H 5)} 2] ( 6) both of which were characterized by X-ray crystallography. In 5 and 6, the indium centres are four-coordinate with a distorted tetrahedral coordination geometry and the thiocyanate groups are bonded through the nitrogen atom. The reaction between 2 and [K(18-crown-6)][SCN] affords the ionic complex [K(18-crown-6)] [In(NCS) 2{Mo(CO) 3(η-C 5H 5)} 2] ( 7) which has also been characterized by X-ray crystallography.

Syntheses and X-ray crystal structures of [bis{(3,5-dimethylpyrazolyl) 3hydridoborato}In]I and [bis{(pyrazolyl) 3methylgallato}In][InI 4

The preparation and X-ray crystal structures of [(HB(pz*) 3) 2In]I and [(MeGa(pz) 3) 2In][InI 4] (pz = pyrazole, pz* = 3,5-dimethylpyrazole) are described. The cations of these complexes correspond to the unknown indocene cations [η 5-C 5R 5In] + (R = H, Me). The indium centre has fac-fac octahedral coordination from the tridentate ligand. The In—N distances are 2.225–2.273(5) Å for the borate and 2.207–2.228(13) Å for the gallate.

Synthetic and structural studies on organoruthenium–indium complexes

The synthesis and X-ray crystal structure of the triruthenium–indium complex [In{Ru(CO)2(η-C5H5)}3]1 are described. Complex 1 comprises a trigonal-planar indium centre bonded to three Ru(CO)2(η-C5H5) fragments by unsupported In–Ru bonds. The magnitude of the In–Ru bond lengths are discussed with respect to π bonding vs. ionic bonding in this and related compounds, and the possibility of π bonding is also addressed with regard to the orientations of the Ru(CO)2(η-C5H5) fragments in 1. The syntheses of the diruthenium complexes [InCl{Ru(CO)2(η-C5H5)}2] and [N(PPh3)2][InCl2{Ru(CO)2(η-C5 H5)}2] are also described together with the X-ray crystal structure of the former.