Terminal Chloride Ligands Research Articles

The Bulk Breast Cancer Cell and Breast Cancer Stem Cell Activity of Binuclear Copper(II)-Phenanthroline Complexes.

Mononuclear copper(II)-phenanthroline complexes have been widely investigated as anticancer agents whereas multinuclear copper(II)-phenanthroline complexes are underexplored. Here the synthesis and characterisation of two new binuclear copper(II)-phenanthroline complexes 1 and 2 is reported, comprising of 2,9-dimethyl-1,10-phenanthroline or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, terminal chloride ligands, and bridging chloride or hydroxide ligands. The binuclear copper(II) complex containing 2,9-dimethyl-1,10-phenanthroline 1 displays nanomolar toxicity towards bulk breast cancer cells and breast cancer stem cells (CSCs) grown in monolayers, >50-fold greater than cisplatin (an anticancer metallodrug) and salinomycin (a gold-standard anti-CSC agent). Spectacularly, 1 exhibits >100-fold greater potency toward three-dimensionally cultured mammospheres than cisplatin and salinomycin. Mechanistic studies show that 1 evokes breast CSC apoptosis by elevating intracellular reactive oxygen species levels and damaging genomic DNA (possibly by an oxidative mechanism). To the best of our knowledge, this is the first study to probe the anti-breast CSC properties of binuclear copper(II)-phenanthroline complexes.

Crystal structure of hexa-kis-(N,N-di-methyl-form-amide-κO)iron(III) μ-chlorido-bis-(tri-chlorido-cadmium).

The title compound, [Fe(C3H7NO)6][Cd2Cl7], crystallizes in the trigonal space group R and is assembled from discrete [Fe(DMF)6]3+ cations (DMF = N,N-di-methyl-formamide) and [Cd2Cl7]3- anions. In the cation, the iron(III) atom, located on a special position of site symmetry, is coordinated by six oxygen atoms from DMF ligands with all Fe-O distances being equal [2.0072 (16) Å]. A slight distortion of the octa-hedral environment of the metal comes from the cis O-Fe-O angles deviating from the ideal value of 90° [86.85 (7) and 93.16 (7)°] whilst all the trans angles are strictly 180°. The central Cl atom of the [Cd2Cl7]3- anion is also located on a special position of site symmetry and bridges two corner sharing, tetra-hedrally coordinated CdII atoms. The two Cd atoms and the central Cl atom are colinear. The two sets of terminal chloride ligands on either side of the dumbbell-like anion are rotated relative to each other by 30°. In the crystal, the cations and anions, stacked one above the other along the c-axis direction, are held in place principally by electrostatic inter-actions. There are also C-H⋯Cl and C-H⋯O inter-actions, but these are rather weak. Of the six crystal structures reported to date for ionic salts of [Fe(DMF)6] n+ cations (n = 2, 3), five contain FeII ions. The title compound is the second example of a stable compound containing the [Fe(DMF)6]3+ cation. The existence of both [Fe(DMF)6]2+ and [Fe(DMF)6]3+ cations shows that the DMF ligand coordination sphere can accommodate changes in the charge and spin states of the metal centre.

Arene platinum group metal complexes containing imino-quinolyl ligands: synthesis and antibacterial studies

Imino-quinolyl Schiff-base ligands have been prepared by the condensation reaction of substituted 2-aminopyridine and quinoline-2-carbaldehyde. The reaction of [(arene)MCl2]2 with imino-quinolyl Schiff-base ligands leads to the formation of cationic complexes [(arene)M(L)Cl]+ (1–12). Single crystal X-ray diffraction studies were used to confirm the coordination mode and structures of these complexes. The molecular structures of these complexes revealed that they adopt characteristic three-legged piano stool geometry with the metal coordinating through a terminal chloride and imino-quinolyl ligands in a bidentate chelating NN′ fashion. The ligand coordinates to the metal center through the nitrogen of the quinoline and the imine nitrogen forming a five-membered metallacycle. These compounds were evaluated for their in vitro antibacterial activity by the agar well diffusion method against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae strains. Results show that all the ligands and complexes inhibited the growth of bacteria.

Synthesis and Characterization of a μ‐Oxo‐Bridged Diferric Complex: An Attempt to Influence the Configuration by Changing the Spacer

The μ‐oxo‐bridged diferric complex [(susanPr){FeIIICl(μ‐O)FeIIICl}](ClO4)2 was synthesized and characterized by single‐crystal X‐ray diffraction, elemental analysis, FT‐IR, UV/Vis/NIR, and Mössbauer spectroscopies as well as magnetic and electrochemical measurements. The properties are compared to the corresponding values for the complex [(susan){FeIIICl(μ‐O)FeIIICl}](ClO4)2, which exhibits a central ethylene spacer, whereas [(susanPr){FeIIICl(μ‐O)FeIIICl}](ClO4)2 has a propylene spacer. Both complexes exhibit a trans configuration of the two terminal chloride ligands. This configuration induces more steric demand in the case of the propylene spacer, which results in a rotation of the two octahedral units along the Fe–(μ‐O)–Fe axis and a tilting of the Fe–N bonds of the diamine spacer. The iron bond lengths are only slightly elongated by the steric demand of the propylene spacer, which is reflected by almost no change in the Mössbauer spectrum. However, the UV/Vis/NIR spectra show a stronger ligand field for [(susanPr){FeIIICl(μ‐O)FeIIICl}](ClO4)2. The slightly longer iron bond lengths result in less electron donation, which is reflected by an anodic shift of 120 mV for the oxidation of the complex. This comparison provides more information on the variation of the properties of the diferric complexes by slight changes in the second coordination sphere.

Ni(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH.

We report the solution and structural chemistry of nickel(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH (PCH[double bond, length as m-dash]NOH). PCH[double bond, length as m-dash]NOH invariably binds in a bidentate manner as illustrated by cis-Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and cis-[Ni(PCH[double bond, length as m-dash]NOH)2]2+ (as its BF4- salt). Treatment of PCH[double bond, length as m-dash]NOH with Ni(OAc)2(H2O)4 gave charge-neutral trans-[Ni(PCH[double bond, length as m-dash]NO)2]0. Treatment of trans-[Ni(PCH[double bond, length as m-dash]NO)2]0 with BF3 gave [Ni(PCH[double bond, length as m-dash]NO)2BF2]BF4. The cation features a planar NiP2N2 center wherein the pair of oximate groups are linked by the difluoroboryl center. The 1 : 1 complexes of the oxime and the oximate are illustrated by [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2 and [Ni(C6F5)(PCH[double bond, length as m-dash]NO)]2, which feature five- and four-coordinate Ni(ii) centers, respectively. All complexes in this series hydrolyze to give the trinickel oxo-phosphine-oximate complex [Ni3(PCH[double bond, length as m-dash]NO)3O]+. One feature of the PCH[double bond, length as m-dash]NOH ligand is its wide bite angle combined with its protic OH center. These aspects are manifested in the structures of Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2, which show intramolecular hydrogen bonding to terminal chloride ligands.

Crystal structure of chlorido-(dimethyl sulfoxide-κS)bis-[4-(pyridin-2-yl)benzaldehyde-κ3C2,N]iridium(III) aceto-nitrile monosolvate.

The title compound, [IrCl(C12H8NO)2{(CH3)2SO}]·H3CCN or [IrCl(fppy)2(DMSO)]·H3CCN [where fppy is 4-(pyridin-2-yl)benzaldehyde and DMSO is dimethyl sulfoxide], is a mononuclear iridium(III) complex including two fppy ligands, a sulfur-coordinating DMSO ligand, and one terminal chloride ligand that define a distorted octa-hedral coordination sphere. The complex crystallizes from 1:1 DMSO-aceto-nitrile as an aceto-nitrile solvate. In the crystal, weak C-H⋯O and C-H⋯N hydrogen-bonding inter-actions between adjacent complexes and between the aceto-nitrile solvent and the complex consolidate the packing.

A novel pentacoordinated cadmium compound:catena-poly[benzyltriethylammonium [[chloridocadmate(II)]-di-μ-chlorido

The structure of the title one-dimensional ABX3-type organic-inorganic hybrid complex, {(C13H22N)[CdCl3]}n, consists of benzyltriethylammonium cations and one-dimensional anionic {[CdCl3](-)}n chains, in which the Cd(II) centres are in an unusual two-layer five-coordinated arrangement. The Cd(II) atom is pentacoordinated by four bridging and one terminal chloride ligand, forming a slightly distorted trigonal bipyramidal ClCd(μ-Cl)4 arrangement. The trigonal bipyramid is linked by two opposite shared faces, giving rise to a zigzag linear anionic {[CdCl3](-)}n chain. The benzyltriethylammonium cations are located in the inter-space of the inorganic network. There are C-H···Cl hydrogen bonds present and these play a crucial role in linking the organic cations and inorganic layers, and also help assemble the components into a three-dimensional network.

Bis{tris[(1H-benzimidazol-3-ium-2-yl)methyl]amine} tetraaquaocta-μ2-chlorido-octachloridopentacadmate(II) monohydrate

The title compound, (C₂₄H₂₄N₇)₂[Cd₅Cl₁₆(H₂O)₄]·H₂O, contains a [Cd₅Cl₁₆(H₂O)₄]⁶⁻ anion, two triply protonated tris[(1H-benzimidazol-3-ium-2-yl)methyl]amine cations and one solvent water molecule. The structure of the anion is a novel chloride-bridged pentanuclear cluster. The five unique CdII centres have quite different coordination environments. Two of the central hexacoordinated CdII cations have a CdOCl₅ chromophore, in which each CdII cation is ligated by four bridging chloride ligands, one terminal chloride ligand and one water molecule, adopting a distorted octahedral environment. The third central CdII cation is octahedrally coordinated by four bridging chloride ligands and two water molecules. Finally, the two terminal CdII cations are pentacoordinated by two bridging and three terminal chloride ligands and adopt a trigonal-bipyramidal geometry. A three-dimensional supramolecular network is formed through intra- and intermolecular O-H∙∙∙O, O-H∙∙∙Cl, N-H∙∙∙Cl and N-H∙∙∙O hydrogen bonds and π-π interactions between the cations and anions.

Di-μ-chlorido-bis[(2-aminobenzamide-κ2N2,O)chloridocopper(II)

The title compound, [Cu2Cl4(C7H8N2O)2], crystallizes as discrete [CuLCl2]2 (L = 2-amino­benzamide) dimers with inversion symmetry. Each CuII ion is five-coordinated and is bound to two bridging chloride ligands, a terminal chloride ligand and a bidentate 2-amino­benzamide ligand. The crystal structure exhibits alternating layers parallel to (010) along the b-axis direction. In the crystal, the components are linked via N—H⋯Cl hydrogen bonds, forming a three-dimensional network. These inter­actions link the mol­ecules within the layers and also link the layers together and reinforce the cohesion of the structure.

Copper(II) Complexes of N,N‐Diisopropylpicolinamide – Solvatochromic and Thermochromic Phase Change of a Monomeric Complex to a Ferromagnetically Coupled Dimeric Complex

AbstractThe synthesis and characterization of mononuclear [Cu(L)2(Cl)2] (1), dinuclear [{CuCl(L)}2(μ‐Cl)2] (2), and another mononuclear complex [Cu(L)2(ClO4)2] (3) with a bidentate N,N‐diisopropylpicolinamide ligand (abbreviated L) are described. Complexes 1 and 2 were obtained from the same reaction mixture and show thermo‐ and solvatochromic behavior. Complex 1 shows irreversible thermochromism by changing into 2 upon heating at 160 °C. These two complexes also show solvatochromism in various solvents. The coordination geometry of the metal ions in 1 and 3 is distorted octahedral, whereas 2 has CuII ions in a distorted square‐pyramidal geometry. Variable‐temperature magnetic susceptibility measurements for the dinuclear copper complex show a ferromagnetic interaction between the CuII ions. The chromotropism has been attributed to a change in geometry from octahedral with terminal chloride ligands to a distorted square‐pyramidal coordination with bridging chloride ions.

A novel cadmium(II) coordination polymer containing two kinds of independent one-dimensional chain

The structure of the title compound, catena-poly[[cadmium(II)-di-μ-chlorido-μ-(1,4-diazoniabicyclo[2.2.2]octane-1-carboxylato)] [[aquachloridocadmium(II)]-di-μ-chlorido] dihydrate], {[Cd(C₈H₁₅N₂O₂)Cl₂][CdCl₃(H₂O)]·2H₂O}n, contains two kinds of independent one-dimensional chain, viz. {[Cd(C₈H₁₅N₂O₂)Cl₂]⁺}n and {[CdCl₃(H₂O)]⁻}n, and uncoordinated water molecules. Each CdII cation in the {[Cd(C₈H₁₅N₂O₂)Cl₂]⁺}n chain is octahedrally coordinated by two pairs of bridging chloride ligands and two O atoms from different bridging carboxylate groups. CdII cations in the {[CdCl₃(H₂O)]⁻}n chain are also octahedrally surrounded by four bridging chloride ligands, one terminal chloride ligand and one coordinated water molecule. Hydrogen bonds between solvent water molecules and these two independent chains generate a three-dimensional framework containing two-dimensional zigzag layers.

Stabilizing the [RSn(μ2-O)SnR] Motif through Intramolecular N→Sn Coordination. Synthesis and Characterization of [(RSn)2(μ2-O)(μ2-FcCOO)2(η-FcCOO)2]·THF and {(RSn)2(μ2-O)[(t-BuO)2PO2]2Cl2}·THF·2H2O (R = 2-(Phenylazo)phenyl)

The reactions of RSnCl3 (1; R = 2-(phenylazo)phenyl) with FcCOOH or di-tert-butyl phosphate in refluxing THF afforded the monoorganodistannoxanes [(RSn)2(μ2-O)(μ2-FcCOO)2(η-FcCOO)2]·THF (2) and {(RSn)2(μ2-O)[(t-BuO)2PO2]2Cl2}·THF·2H2O (3). The molecular structure of 2 contains seven-coordinate tin centers in a distorted-pentagonal-bipyramidal geometry, while 3 contains six-coordinate tin centers in a distorted-octahedral geometry. In the dinuclear compounds 2 and 3 the two tin centers are bridged by a μ2-O unit, affording a rare Sn–O–Sn motif among monoorganostannoxanes. In addition, each tin is also intramolecularly coordinated to the nitrogen atom of the 2-phenylazophenyl substituent (N→Sn). Further, in 2, the two tin centers are bridged by two isobidentate ferrocenecarboxylate ligands; each tin center also is bound to a chelating ferrocenecarboxylate ligand. On the other hand, in 3, while the two tin centers are bridged by two isobidentate di-tert-butyl phosphate ligands, each tin center also has a terminal chloride ligand.

A potential molecular ferroelectric material: poly[[bis(1-aza-4-azoniabicyclo[2.2.2]octane)di-μ3-chlorido-tetra-μ2-chlorido-dichloridotricadmium(II)] dihydrate

The title compound, {[Cd3(C6H13N2)2Cl8]·2H2O}n, consists of pendant protonated cationic diamine ligands bonded to an anionic one-dimensional coordination polymer chloridocadmate scaffold. Each coordination chain features two kinds of Cd(II) centre, each with distorted octahedral coordination geometry. One Cd(II) cation lies on a centre of inversion and is coordinated by six bridging chloride ligands, while the other is coordinated by four bridging chloride ligands, one terminal chloride ligand and a 1-aza-4-azoniabicyclo[2.2.2]octane aza N atom. This gives a reversible corner-sharing half-cubic linear polymer that lies along the crystallographic a direction. The chains interact through hydrogen bonding with solvent water, with each water molecule accepting one N-H...O interaction from a cation and donating to two O-H...Cl interactions with anionic chains, thus linking three separate chains and completing the packing structure.

Synthesis and Characterization of Palladium Complexes Supported by an NPN-Phosphido Ancillary Ligand

The PdII coordination chemistry of the phosphido ligand [(2-Me2NC6H4)2P]− (NPN) is reported, along with the results of studies documenting the utility of such complexes as catalyst precursors for the Heck arylation of olefins. Examples of κ1-, κ2-, and κ3-NPN coordination to Pd are described. The secondary phosphine (NPN)H (1) was reacted with 0.5 equiv of [(C3H5)PdCl]2 to afford the dimeric species [(κ2-NPN)PdCl]2 (2) in 96% yield. Similarly, the reaction of 1 with 0.33 equiv of [Pd(OAc)2]3 led to the formation of dimeric [(κ2-NPN)PdOAc]2 (3) in 98% yield. Complexes 2 and 3 were both crystallographically characterized to reveal dipalladium species that feature bridging phosphido groups, as well as terminal chloride and acetate ligands, respectively. Treatment of 3 with Me3SiOTf resulted in the formation of the analogous triflate complex [(κ2-NPN)PdOTf]2 (4; 78% yield). Treatment of 2 with (C3H5)MgCl afforded the thermally sensitive, phosphido-bridged complex [(κ1-NPN)Pd(η3-C3H5)]2 (5) in 87% yield. The s...

Cl5Ta(μ-O)TaCl3{iPrS(CH2)2SiPr}] and [(TaCl4)2(μ-O)(μ-Me2Se2)]: two chalcogenoether complexes of Ta2OCl8with very different geometries

The title compounds, [1,2-bis(isopropylsulfanyl)ethane-2κ(2)S,S']octachlorido-1κ(5)Cl,2κ(3)Cl-μ-oxido-ditantalum(V), [Ta(2)Cl(8)O(C(8)H(18)S(2))], (I), and μ-dimethyldiselane-κ(2)Se:Se'-μ-oxido-bis[tetrachloridotantalum(V)], [Ta(2)Cl(8)O(C(2)H(6)Se(2))], (II), contain six-coordinate Ta(V) centres linked by a nonlinear oxide bridge. Compound (I) contains one Ta(V) centre bonded to a chelating dithioether and three terminal chloride ligands, with the second Ta(V) centre bonded to five terminal chloride ligands. In (II), two tetrachloridotantalum(V) residues are bridged by the diselenide, giving a puckered five-membered Ta/O/Ta/Se/Se ring. The Ta-O distances in the bridges are short in both compounds, indicating that significant multiple-bond character is retained despite the deviation from linearity, and the bond lengths reveal a clear trans influence order of O > Cl > S > Se on the hard Ta(V) centre. The structures are compared with the [Ta(2)Cl(10)O](2-) anion, which contains a linear oxide bridge.

(1R*,2S*)-N-Benzyl-2-phenyl-1-(pyridin-2-yl)-N-(pyridin-2-ylmeth-yl)ethane-1,2-diamine]-dichloridozinc(II).

In the mononuclear zinc title complex, [ZnCl2(C26H26N4)], the ZnII ion is surrounded by three N atoms from a (1R*,2S*)-N 1-benzyl-2-phenyl-1-(pyridin-2-yl)-N 2-(pyridin-2-ylmeth­yl)ethane-1,2-diamine (BPPPEN) ligand and two terminal chloride ligands, resulting in a highly distorted environment around the metal atom. The calculated τ parameter of 0.42 indicates that the coordination geometry is approximately square-pyramidal. Hydrogen bonds involving centrosymmetric N—H⋯Cl inter­actions form dimeric structures. The mol­ecules are stacked along the a and b axes.

Study of complexes of platinum group metals containing nitrogen bases derived from pyridine aldehydes: Interesting molecular structures with unpredicted bonding modes of the ligands

A series of mono-cationic dinuclear half sandwich ruthenium, rhodium and iridium metal complexes have been synthesized using ((pyridin-2-yl)methylimino)nicotinamide ( L1) and ((picolinamido)phenyl)picolinamide ( L2) ligands: [(η 6-arene) 2Ru 2(μ- L1)Cl 3] + (arene = C 6H 6, 1; p- iPrC 6H 4Me, 2; C 6Me 6, 3), [(η 5-C 5Me 5) 2M 2(μ- L1)Cl 3] + (M = Rh, 4; Ir, 5), and [(η 6-arene) 2Ru 2(μ- L2)(μ-Cl)] + (arene = C 6H 6, 6; p- iPrC 6H 4Me, 7; C 6Me 6, 8), [(η 5-C 5Me 5) 2M 2(μ- L2)Cl 2] + (M = Rh, 9; Ir, 10). All the complexes have been isolated as their hexafluorophosphate salts and fully characterized by use of a combination of NMR and IR spectroscopy. The solid state structure of three representatives 4, 6 and 9 has been determined by X-ray crystallographic studies. Interestingly, in the molecular structure of 4, the first metal is bonded to two nitrogen atoms whereas the second metal center is coordinated to only one nitrogen atom with two terminal chloride ligands. Fascinatingly in the case of the complexes with the symmetrical ligand L2, both ruthenium centers having η 6-arene groups are bonded to nitrogen atoms with a bridging chloride atom between the two metal centers, whereas the metals with η 5-Cp∗ groups are bonded to the ligand N,O and N,N fashion.

W3Cl10(Hg2Cl2)2, A Reactive One-Dimensional Polymer of Triangular Tritungsten Clusters with Terminal and Intercluster-Bridging Mercurous Chloride Ligands: Main Group Metal Halide By-Products as Versatile Ligands in Reductive Synthesis of Early Transition Metal Halide Clusters

Solid-state reduction of WCl6 with Hg followed by incomplete sublimation of mercury chlorides generated the tritungsten decachloride—mercury chloride adducts W3Cl10(Hg2Cl2)2−x(HgCl2)x. Thermal equilibration of the solid-state products followed by sublimation of HgCl2 afforded single crystals that include the mercurous chloride adduct W3Cl10(Hg2Cl2)2. Single-crystal diffractometry revealed a one-dimensional polymer of tritungsten decachloride triangular clusters with novel terminal and inter-cluster-bridging ClHgHgCl ligands. The W3 cluster core has similar metrics to that of the benzyltriethylammonium salt of W3(μ3-Cl)(μ-Cl)3Cl9 3−. W3Cl10(Hg2Cl2)2 is the first reported adduct of the binary tungsten chloride W3Cl10. The ClHgHgCl ligands are more labile that the terminal chlorine atoms of W3(μ3-Cl)(μ-Cl)3Cl9 3−. These results demonstrate diverse roles and potential utility of main group element halide by-product ligands in solid-state reductions of transition metal halides.

Homoleptic Tris(Pyridyl Pyrazolate) IrIII Complexes: En Route to Highly Efficient Phosphorescent OLEDs

Treatment of the metal reagent IrCl(3)nH(2)O with two equivalents of 2-pyridyl pyrazole (N;N)H (3-tert-butyl-5-(2-pyridyl) pyrazole, (bppz)H and 3-trifluoromethyl-5-(2-pyridyl) pyrazole, (fppz)H), afforded the isomeric Ir(III) metal complexes with a general formula cis-[Ir(bppz)(2)Cl(2)]H (2 a), trans-[Ir(bppz)(2)Cl(2)]H (3 a), cis-[Ir(fppz)(2)Cl(2)]H (2 b), and trans-[Ir(fppz)(2)Cl(2)]H (3 b). Single-crystal X-ray diffraction studies on 2 b and 3 a revealed the coexistence of two pyrazolate chelates and two terminal chloride ligands on the coordination sphere. Subsequent reactivity studies confirmed their intermediacy to the preparation of homoleptic mer-[Ir(bppz)(3)] (1 a) and mer-[Ir(fppz)(3)] (1 b) that showed dual intraligand and ligand-to-ligand charge-transfer phosphorescence at room temperature. To attain bright, room-temperature phosphorescence further, we then synthesized two isoquinolinyl pyrazolate complexes, mer-[Ir(bipz)(3)] (4 a) and mer-[Ir(fipz)(3)] (4 b) ((bipz)H=3-tert-butyl-5-(1-isoquinolyl) pyrazole and (fipz)H=3-trifluoromethyl-5-(1-isoquinolyl) pyrazole). Their orange luminescence is mainly attributed to the mixed MLCT/pipi* transition, and the quantum yields were as high as 86 (4 a) and 50 % (4 b) in degassed CH(2)Cl(2) solution at RT. The organic light-emitting diodes (OLEDs) were then fabricated by using 4 a as a dopant, giving orange luminescence with CIE(x,y)=0.55, 0.45 (CIE(x,y)=the 1931 Commission Internationale de L'Eclairage (x,y) coordinates) and peak efficiencies of 14.6 % photon/electron, 34.8 cd A(-1), 26.1 lm W(-1). The device data were then compared with the previously reported heteroleptic complex [Ir(dfpz)(2)(bipz)] (5) ((dfpz)H=1-(2,4-difluorophenyl) pyrazole), revealing the possible effect of the bipz chelate and phosphor design on the overall electrophosphorescent performance, which can be understood by the differences in the carrier-transport properties.

Dinuclear Chlorido‐, Alkyl(chlorido)‐, and Hydridoyttrium Complexes Supported by μ‐Bridging‐Silyl‐Linked Bis(amidinate) Ligands

AbstractA chloridoyttrium complex supported by a silyl‐linked bis(amidinate) ligand, [(Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2)2(YCl)2(μ‐Cl)]–[Li(thf)4]+ (2) (thf = tetrahydrofuran), was synthesized by the reaction of equimolar amounts of anhydrous YCl3 and lithium amidinate [(Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2)2Li3]–[Li(thf)4]+ (1) in thf at 20 °C. Complex 2 was isolated after recrystallization from a thf/hexane mixture in 72 % yield. Single‐crystal X‐ray structure analysis has revealed that 2 is a dinuclear compound composed of a discrete complex anion [(Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2)2(YCl)2(μ‐Cl)]–, containing one μ‐bridging and two terminal chloride ligands, and a cation [Li(thf)4]+. The formation of a dimeric structure results from the coordination of amidinate fragments of the same dianionic ligand on two different yttrium ions and the presence of a μ‐bridging chloride ligand. Alkylation of 2 with one equivalent of Me3SiCH2Li in toluene afforded an alkyl(chlorido)yttrium complex, [Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2]2[Y(thf)](μ‐Cl)[Y(CH2SiMe3)] (3). X‐ray crystal structure investigation has shown that 3 is a dimeric complex as a result of the “spanning” coordination mode of the ansa‐bis(amidinate) ligands and the presence of one μ2‐chloride ligand, while the alkyl group remains terminal. Treatment of the in situ generated alkyl derivative [Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2]2[Y(CH2SiMe3)]2 (4) with PhSiH3 in toluene results in the formation of the corresponding hydridoyttrium complex [Me2Si{NC(Ph)N(2,6‐iPr2–C6H3)}2Y(μ‐H)]2 (5), which was isolated after recrystallization from toluene in 73 % yield. According to the X‐ray crystal structure analysis, 5 adopts a dimeric structure with two μ‐bridging bis(amidinate) and two μ2‐hydrido ligands.