Iodide Ligands Research Articles

Aerobic method for the synthesis of nearly size-monodisperse bismuth nanoparticles from a redox non-innocent precursor

Herein, we report an aerobic synthesis method to produce bismuth nanoparticles (Bi NPs) with average diameters in the range 40–80 nm using commercially available bismuth triiodide (BiI3) as the starting material; the method uses only readily available chemicals and conventional laboratory equipment. Furthermore, size data from replicates of the synthesis under standard reaction conditions indicate that this method is highly reproducible in achieving Bi NP populations with low standard deviations in the mean diameters. We also investigated the mechanism of the reaction, which we determined results from the reduction of a soluble alkylammonium iodobismuthate precursor species formed in situ. Under appropriate concentration conditions of iodobismuthate anion, we demonstrate that burst nucleation of Bi NPs results from reduction of Bi3+ by the coordinated, redox non-innocent iodide ligands when a threshold temperature is exceeded. Finally, we demonstrate phase transfer and silica coating of the Bi NPs, which results in stable aqueous colloids with retention of size, morphology, and colloidal stability. The resultant, high atomic number, hydrophilic Bi NPs prepared using this synthesis method have potential for application in emerging x-ray contrast and x-ray therapeutic applications.

Highly Efficient Inverted Structural Quantum Dot Solar Cells.

Highly efficient PbS colloidal quantum dot (QD) solar cells based on an inverted structure have been missing for a long time. The bottlenecks are the construction of an effective p-n heterojunction at the illumination side with smooth band alignment and the absence of serious interface carrier recombination. Here, solution-processed nickel oxide (NiO) as the p-type layer and lead sulfide (PbS) QDs with iodide ligand as the n-type layer are explored to build a p-n heterojunction at the illumination side. The large depletion region in the QD layer at the illumination side leads to high photocurrent. Interface carrier recombination at the interface is effectively prohibited by inserting a layer of slightly doped p-type QDs with 1,2-ethanedithiol as ligands, leading to improved voltage of the device. Based on this graded device structure design, the efficiency of inverted structural heterojunction PbS QD solar cells is improved to 9.7%, one time higher than the highest efficiency achieved before.

Lanthanoid Pseudo-Grignard Reagents: A Major Untapped Resource.

Pseudo-Grignard reagents PhLnI (Ln=Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at -78 °C in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with a range of bulky N,N'-bis(aryl)formamidines to generate an extensive series of LnII or more rarely LnIII complexes, namely [Eu(DippForm)I(thf)4 ]⋅thf (1), [{EuI2 (dme)2 }2 ] (2), [Eu(XylForm)I(dme)2 ]⋅0.5 dme (3 a), [Eu(XylForm)I(dme)(μ-dme)]n (3 b), [{Eu(XylForm)I(μ-OH)(thf)2 }2 ] (4), [Yb(DippForm)I(thf)3 ]⋅thf (5 a), [Yb(DippForm)I2 (thf)3 ]⋅2 thf (5 b), [{Yb(MesForm)I(thf)2 }2 ] (6), [{Yb(XylForm)I(thf)2 }2 ] (7 a), and [Yb(XylForm)2 I(dme)]⋅dme (7 b) {(Form=ArNCHNAr; XylForm (Ar=2,6-Me2 C6 H3 ), MesForm (Ar=2,4,6-Me3 C6 H2 ), DippForm (Ar=2,6-iPr2 C6 H3 )}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reaction with XylFormH in THF gave 4. Europium complexes 1 and 3 a are seven-coordinate divalent monomers, whilst 3 b is a seven-coordinate dme-bridged polymer. Complex 5 a of the smaller YbII is a six-coordinate monomer, but the related 6 and 7 a are six-coordinate iodide-bridged dimers. 4 is a trivalent seven-coordinate hydroxide-bridged dimer, whereas complexes 5 b and 7 b are seven-coordinate monomeric YbIII derivatives. A characteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand. To illustrate the synthetic scope of the pseudo-Grignard reagents, [Yb(Ph2 pz)I(thf)4 ] (Ph2 pz=3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium(III) iodide [Yb(Ph2 Pz)I2 (thf)3 ] (8) in high yield, whilst metathesis between [Yb(Ph2 pz)I(thf)4 ] and NaCp (Cp=C5 H5 ) gave [Yb(C5 H5 )(Ph2 pz)(thf)]n (9), a nine-coordinate η5 :η5 -Cp-bridged coordination polymer. Reaction of the pseudo-Grignard reagent MeYbI with KN(SiMe3 )2 gave [K(dme)4 ][Yb{N(SiMe3 )2 }3 ] (10) with a charge-separated three-coordinate homoleptic [Yb{N(SiMe3 )2 }3 ]- anion, a complex that could be obtained in high yield by deliberate synthesis from YbI2 and KN(SiMe3 )2 in DME.

Ligand Influence on the Photophysical Properties and Electronic Structures of Tungsten Iodide Clusters

Compounds containing the [Mo6I8L6]2– ion in which L is an inorganic or organic ligand show remarkable photophysical properties. Similar properties were observed for the corresponding compounds based on octahedral tungsten clusters. The properties of these photosensitizers are significantly impacted by the six outer iodide ligands of [W6I8I6]2–. To analyze the role of the outer ligands, we prepared and structurally characterized octahedral tungsten cluster compounds with [W6I8I6]2– and [M6I8L6]2– ions (M = W, Mo; L = para‐toluenesulfonate). The distinct photophysical properties of the clusters were analyzed with respect to their photoluminescence (i.e., phosphorescence) and luminescence quenching in the presence of molecular oxygen. The electronic structures were analyzed through photoelectron spectroscopy to expose differences in the electronic situations of the compounds.

Insertion of carbenoids into X-H bonds catalyzed by the cyclobutadiene rhodium complexes

The cyclobutadiene rhodium complex [(C4Et4)RhCl]2 (generated from [(C4Et4)Rh(p-xylene)]PF6 and BnNEt3Cl) catalyzes the reaction of methyl α-diazophenylacetate with RnX-H compounds to give the insertion products methyl 2-RnX-2-phenylacetates in 70–90% yields (RnX-H = methanol, tert-butylamine, 2,6-diisopropylaniline, morpholine, diallylamine, triethylsilane, triethylamine-borane). The stoichiometric reaction of [(C4Et4)RhI]2 with methyl α-diazophenylacetate gives the intermediate complex (C4Et4)2Rh2(μ-I)2(μ-1-carboxymethyl-1-phenylmethylene), which has a binuclear structure with bridging iodide and carbene ligands. This result indicates that catalytically active carbene species may have more complex structures than the commonly assumed LnM=CR2.

In-Cell Activation of Organo-Osmium(II) Anticancer Complexes.

The family of iodido OsII arene phenylazopyridine complexes [Os(η6‐p‐cym)(5‐R1‐pyridylazo‐4‐R2‐phenyl))I]+ (where p‐cym=para‐cymene) exhibit potent sub‐micromolar antiproliferative activity towards human cancer cells and are active in vivo. Their chemical behavior is distinct from that of cisplatin: they do not readily hydrolyze, nor bind to DNA bases. We report here a mechanism by which they are activated in cancer cells, involving release of the I− ligand in the presence of glutathione (GSH). The X‐ray crystal structures of two active complexes are reported, 1‐I (R1=OEt, R2=H) and 2‐I (R1=H, R2=NMe2). They were labelled with the radionuclide 131I (β−/γ emitter, t1/2 8.02 d), and their activity in MCF‐7 human breast cancer cells was studied. 1‐[131I] and 2‐[131I] exhibit good stability in both phosphate‐buffered saline and blood serum. In contrast, once taken up by MCF‐7 cells, the iodide ligand is rapidly pumped out. Intriguingly, GSH catalyzes their hydrolysis. The resulting hydroxido complexes can form thiolato and sulfenato adducts with GSH, and react with H2O2 generating hydroxyl radicals. These findings shed new light on the mechanism of action of these organo‐osmium complexes.

Halogenated PtIV Complexes from N‐Halosuccinimide Oxidation of PtII Antitumor Drugs: Synthesis, Mechanistic Investigation, and Cytotoxicity

Compared with square‐planar PtII drugs, PtIV‐based anticancer prodrugs are relatively inert under physiological conditions and can be activated after entering cells. The two axial ligands in PtIV complexes provide an opportunity to further functionalize these prodrugs. In recent years, much effort has been devoted to developing new PtIV‐based anticancer prodrugs with higher cytotoxicity but fewer side effects. New synthetic methods, however, are intensely desired for structurally diversified and biologically distinct PtIV complexes. Herein, we utilize N‐halosuccinimides as oxidants and carry out the oxidation reaction on PtII drugs including cisplatin, carboplatin, and oxaliplatin to obtain halogenated PtIV complexes. The related mechanism of the reaction of N‐bromosuccinimide (NBS) with cisplatin in ethanol is thoroughly investigated. N‐chlorosuccinimide is also utilized to obtain the respective dichlorinated PtIV complexes. When N‐iodosuccinimide reacts with PtII drugs, new PtIV compounds containing iodide and succinimide ligands in the axial position are formed. Cytotoxicity test shows that some of the complexes are active against cisplatin‐resistant human ovarian cancer cells. Our study provides a detailed understanding of the reaction mechanism between NBS and cisplatin and offers a more convenient strategy to obtain dichlorinated and new iodinated PtIV anticancer prodrugs.

Crystal structure of (aceto-nitrile-κN)iodido-(2-(naphthalen-1-yl)-6-{1-[(2,4,6-tri-methyl-phen-yl)imino]ethyl}-pyridine-κ2N,N')copper(I).

In the mononuclear title complex, [CuI(C2H3N)(C26H24N2)], the CuI ion has a distorted tetra-hedral coordination environment, defined by two N atoms of the chelating 2-(naphthalen-1-yl)-6-[(2,4,6-tri-methyl-phen-yl)imino]-pyridine ligand, one N atom of an aceto-nitrile ligand and one iodide ligand. Within the complex, there are weak intra-molecular C-H⋯N hydrogen bonds, while weak inter-molecular C-H⋯I inter-actions between complex mol-ecules, help to facilitate a three-dimensional network.

Ligand Exchange Processes in Abnormal N‐heterocyclic Carbene Rhodium Complexes

AbstractRhodium(III) complexes containing a mesoionic and strongly electron‐donating abnormal dicarbene ligand and a phosphine in a facial coordination mode and three ancillary iodide ligands undergo spontaneous solvolysis to give a cationic complex with an iodide in the outer coordination sphere. The availability of this non‐coordinating iodide promotes a halide exchange reaction and in chlorinated solvents such as chlorocyclohexane, chloroethyl benzene, 1,2‐dichloroethane, and benzyl chloride, the metal‐coordinated iodo ligands exchange for chlorides. Mechanistic investigations suggest that the role of the metal is to release the iodide anion, rather than being directly involved in the C–Cl bond activation. The release of the iodide from the metal coordination sphere is promoted by the strong donor ability of the abnormal dicarbene ligand.

One-step synthesis of oxamidato bridged fac-Ru(CO)3 core based dinuclear compounds: Spectroscopic and structural characterisation

Oxamidato bridged fac-Ru(CO)3 core based dinuclear compounds of general formula [I(CO)3Ru(μ-L)Ru(CO)3I] (1–3) were synthesised by oxidative addition of oxamide ligands (H2L = N,N′-dibutyloxamide, N,N′-diphenyloxamide, and N,N′-dibenzyloxamide) and iodine to ruthenium carbonyl (Ru3(CO)12) in one-pot reaction under solvothermal conditions. The dinuclear compounds 1–3 were characterised using elemental analyses, IR, UV–Vis and NMR spectroscopic techniques. All these compounds were structurally characterised by single crystal X-ray diffraction methods. The molecular structure of 1–3 consists of a dinuclear framework in which two Ru(CO)3I units are associated together by a bridging oxamide ligand via NO∩ON bis-chelation. The iodide ligands on two ruthenium centres are oriented in a trans-fashion with respect to each other. The reaction proceeded via formation of an iodido bridged intermediate compound [I(CO)3Ru(μ-I)2Ru(CO)3I]. The present account of research comprises a first set of neutral fac-Ru(CO)3 core based dinuclear compounds containing bis-chelating oxamide ligands obtained in single-step.

Crystal structure of (4-fluoro-phenyl-κC (1))iodido-(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ(2) N,N')palladium(II).

In the title compound, [Pd(C6H4F)I(C6H16N2)], the PdII atom is coordinated by two N atoms from the N,N,N′,N′-tetra­methyl­ethylenedi­amine ligand, a C atom of the 4-fluoro­phenyl group and an iodide ligand in a distorted square-planar geometry, with an average deviation from the least-squares plane through the ligand donor atoms of 0.0159 (2) Å. The angles about the PdII atom range from 83.35 (16) to 178.59 (11)°. In the crystal, weak C—H⋯F and C—H⋯I hydrogen bonds link the mol­ecules into sheets in the bc plane.

Optimization of hydrogen-evolving photochemical molecular devices.

A molecular photocatalyst consisting of a Ru(II) photocenter, a tetrapyridophenazine bridging ligand, and a PtX2 (X=Cl or I) moiety as the catalytic center functions as a stable system for light-driven hydrogen production. The catalytic activity of this photochemical molecular device (PMD) is significantly enhanced by exchanging the terminal chlorides at the Pt center for iodide ligands. Ultrafast transient absorption spectroscopy shows that the intramolecular photophysics are not affected by this change. Additionally, the general catalytic behavior, that is, instant hydrogen formation, a constant turnover frequency, and stability are maintained. Unlike as observed for the Pd analogue, the presence of excess halide does not affect the hydrogen generation capacity of the PMD. The highly improved catalytic efficiency is explained by an increased electron density at the Pt catalytic center, this is confirmed by DFT studies.

AuHg(o-C6H4PPh2)2I]: A Dinuclear Heterometallic Blue Emitter

The heteronuclear AuI/HgII complex [AuHg(o-C6H4PPh2)2I] (1) was prepared by reacting of [Hg(2-C6H4PPh2)2] with [Au(tht)2]ClO4 (1:1) and NaI in excess. The heterometallic compound 1 has been structurally characterized and shows an unusual blue luminescent emission in the solid state. Theoretical calculations suggest that that the origin of the emission arises from the iodide ligand arriving at metal-based orbitals in a Ligand to Metal-Metal Charge Transfer transition.

New rhenium carbonyl cluster complexes containing bridging hydrocarbyl and bridging mercury groups

The new rhenium–mercury complexes [Re2(CO)8(μ-HgI)(μ-η1-C6H5)]2, 2 and [Re2(CO)8[μ-HCC(H)C4H9]2(μ4-Hg), 3 were obtained from the reactions of Re2(CO)8[μ-Au(PPh3)](μ-η1-C6H5), 1 with HgI2 and of Re2(CO)8[μ-HCC(H)C4H9](μ-H) with Hg(C6H5)2, respectively. In the solid state compound 2 is dimer of Re2(CO)8(μ-HgI)(μ-η1-C6H5) that held together by iodide ligands that asymmetrically bridge between the two mercury atoms. Each dirhenium group is formally electronically unsaturated and contains one bridging η1-C6H5 ligand. Compound 3 contains two Re2(CO)8[μ-HCC(H)C4H9]2 groups held together by a quadruply bridging spiro-structured mercury atom.

Hybrid inorganic-organic materials with an optoelectronically active aromatic cation: (C7H7)2SnI6 and C7H7PbI3.

Inorganic materials with organic constituents-hybrid materials-have shown incredible promise as chemically tunable functional materials with interesting optical and electronic properties. Here, the preparation and structure are reported of two hybrid materials containing the optoelectronically active tropylium ion within tin- and lead-iodide inorganic frameworks with distinct topologies. The crystal structures of tropylium tin iodide, (C7H7)2SnI6, and tropylium lead iodide, C7H7PbI3, were solved using high-resolution synchrotron powder X-ray diffraction informed by X-ray pair distribution function data and high-resolution time-of-flight neutron diffraction. Tropylium tin iodide contains isolated tin(IV)-iodide octahedra and crystallizes as a deep black solid, while tropylium lead iodide presents one-dimensional chains of face-sharing lead(II)-iodide octahedra and crystallizes as a bright red-orange powder. Experimental diffuse reflectance spectra are in good agreement with density functional calculations of the electronic structure. Calculations of the band decomposed charge densities suggest that the deep black color of tropylium tin iodide is attributed to iodide ligand to tin metal charge transfer, while the bright red-orange color of tropylium lead iodide arises from charge transfer between iodine and tropylium states. Understanding the origins of the observed optoelectronic properties of these two compounds, with respect to their distinct topologies and organic-inorganic interactions, provides insight into the design of tropylium-containing compounds for potential optical and electronic applications.

Coordinatively Unsaturated T-Shaped Platinum(II) Complexes Stabilized by Small N-Heterocyclic Carbene Ligands. Synthesis and Cyclometalation

The reaction of the N-heterocyclic carbenes (NHCs) IiPr2Me2 and IiPr2 with [PtMe3I]4 does not lead to the clean formation of complexes trans-[PtMeI(NHC)2], as previously found for bulkier NHCs. However, these species can be prepared in high yields by an alternative procedure using the dimethyl species [PtMe2(NHC)2] and iodomethane. The halogenated complexes trans-[PtMeI(NHC)2] have been used as precursors for the formation of the coordinatively unsaturated Pt(II) derivatives [PtMe(NHC)2][SbF6] using AgSbF6 as a halogen abstractor, whereas NaBArF is not reactive enough to completely remove the iodide ligand, leading instead to the dinuclear species [Pt2(μ-I)(Me)2(NHC)4][BArF]. Alternatively, low-coordinate T-shaped complexes [PtMe(NHC)2][BArF] can be prepared by protonation of the dimethyl species [PtMe2(NHC)2] with [H(OEt2)2][BArF]. The complex [PtMe(IiPr2Me2)2][BArF] undergoes a cyclometalation process under mild heating, leading to the derivative [Pt(IiPr2Me2′)(IiPr2Me2)][BArF] (where the prime denotes the cyclometalated ligand). This result is in contrast with the fast cyclometalation observed for the related Pt(II) complex bearing tert-butyl-substituted NHC (ItBu). Different cyclometalation reaction mechanisms have been computationally addressed. DFT calculations indicate that the cyclometalation involving complexes with not very bulky NHCs ligands occurs via cis intermediates. Cyclometalation products bearing tert-butyl-substituted NHCs are kinetically and thermodynamically favored over those involving isopropyl groups.

Combined post-modification of iodide ligands and wide band gap ZnS in quantum dot sensitized solar cells.

Combined post-modification strategy of iodide ligands and wide band gap ZnS layer were employed in quantum dot sensitized solar cells. J-V curves show that the combined post-modification could improve the photoconversion efficiency compared to the single post-modification of ZnS because of the more effective passivation. CdS-sensitized and CdS/CdSe-co-sensitized solar cells both reveal that the assembly structure of QDs/I(-)/ZnS is more beneficial for the efficiency of solar cells than that of QDs/ZnS/I(-). EIS results show that the former structure exhibit higher interface resistance and could suppress electron recombination more powerfully. XPS results reveal that the iodide ligands have different binding energy, which indicates a different coordination state of the iodide atom in these two structures. Finally, 3.28% efficiency and 18.16 mA cm(-2) were achieved for CdS/CdSe QDSCs by applying this combined post-modification.

(η4-Cyclooctatetraene)(η8-cyclooctatetraene)iodidotantalum(V)

The title complex, [Ta(η4-C8H8)(η8-C8H8)I], lies across a crystallographic mirror plane that includes the TaV atom and the iodide ligand. One cyclo­octa­tetra­ene (cot) ring is η4-coordinating and is bis­ected by the mirror plane. The fold angle between the plane of the coordinating butadiene portion and the middle plane of the ring is 27.4 (4)°. An additional minor fold angle of 9.3 (7)° exists between the final plane in the ring and the middle plane. The other cot ring is η8-coordinating and is also cut by the mirror plane. In this case, the ring is disordered over the mirror plane, and one position is modeled with appropriate restraints and constraints with respect to distances, angles and displacement parameters (the second position is generated by symmetry). This ring is nearly planar, with an r.m.s. deviation of only 0.05 Å when all eight C atoms are included in the calculation. Pairs of inter­molecular η8-cot rings are parallel stacked and slightly off center, with a centroid–centroid distance of 3.652 Å. No other significant inter­molecular inter­actions are observed. The compound is of inter­est as the first structurally characterized mixed halogen–cot complex of the group 5 metals and contains the longest terminal Ta—I distance [3.0107 (5) Å] reported to date.

Simple Manual Grinding Synthesis of Highly Luminescent Mononuclear Cu(I)–Iodide Complexes

Abstract Highly luminescent mononuclear copper(I)–iodide complexes [CuI(PPh3)2(L)] have been synthesized by simple manual grinding of copper(I) iodide, PPh3, and N-heteroaromatic ligands (L = isoquinoline, 1,6-naphthyridine, and pyridine). They exhibit different colors of luminescence depending on L affording very high quantum yields (0.63–0.99).

Nickel hexa-yttrium deca-iodide, [NiY6]I10.

Comproportionation reactions of yttrium triiodide, yttrium and nickel led to the formation of the compound [NiY6]I10, which is isostructural with the prototypical [RuY6]I10. In particular, [NiY6]I10 is composed of isolated nickel centered yttrium octa­hedra (site symmetry -1) that are further surrounded by iodide ligands to construct a three-dimensional cluster complex framework. Although this compound has been previously detected by powder X-ray diffraction techniques [Payne & Corbett (1990 ▶). Inorg. Chem. 29, 2246–2251], details of the crystal structure for triclinic [NiY6]I10 were not provided.