The reactions of the disodium salt of the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) ligand with one equivalent of Me2AlCl in diethyl ether, toluene, and benzene produced the complexes [Na(Et2O)2(dpp-BIAN)AlMe2] (1), [Na(eta6-C7H8)(dpp-BIAN)AlMe2] (2) and [Na(eta6-C6H6)(dpp-BIAN)AlMe2] (3), respectively. Recrystallization of 1 from hexane afforded solvent-free [{Na(dpp-BIAN)AlMe2}n] (4) or [Na(Et2O)(dpp-BIAN)AlMe2] (5) depending on the temperature of the solvent. The molecular structures of 1-5 have been determined by single-crystal X-ray diffraction. The sodium cation coordinates either one of the naphthalene rings (1) or the diimine part of the dpp-BIAN ligand (2-5). In the complexes 2 and 3, the sodium cation additionally coordinates the toluene (2) or benzene molecule (3) in an eta6-fashion. 相似文献
The neutral pentacoordinate silicon(IV) complexes 8 and 9 with an SiO2N3 skeleton and the neutral hexacoordinate silicon(IV) complex 10.1/2 CH3CN with an SiO4N2 skeleton were synthesized, starting from tetra(cyanato-N)silane or tetra(thiocyanato-N)silane. Compounds 8 and 9 contain one tridentate dianionic ligand derived from 4-[(2-hydroxyphenyl)amino]pent-3-en-2-one and two monodentate singly charged cyanato-N or thiocyanato-N ligands bound to the silicon(IV) coordination center, whereas the silicon(IV) center of 10 is coordinated by two of these tridentate dianionic ligands. All compounds were characterized by single-crystal X-ray diffraction and solid-state and solution NMR spectroscopy. To get more information about the stereochemistry of the compounds studied, the experimental investigations were complemented by computational studies. 相似文献
The use of pincer ligands to access non-VSEPR geometries at main-group centers is an emerging strategy for eliciting new stoichiometric and catalytic reactivity. As part of this effort, several different tridentate trianionic substituents have to date been employed at a range of different central elements, providing a patchwork dataset that precludes rigorous structure–function correlation. An analysis of periodic trends in structure (solid, solution, and computation), bonding, and reactivity based on systematic variation of the central element (P, As, Sb, or Bi) with retention of a single tridentate triamide substituent is reported herein. In this homologous series, the central element can adopt either a bent or planar geometry. The tendency to adopt planar geometries increases descending the group with the phosphorus triamide ( 1 ) and its arsenic congener ( 2 ) exhibiting bent conformations, and the antimony ( 3 ) and bismuth ( 4 ) analogues exhibiting a predominantly planar structure in solution. This trend has been rationalized using an energy decomposition analysis. A rare phase-dependent dynamic covalent dimerization was observed for 3 and the associated thermodynamic parameters were established quantitatively. Planar geometries were found to engender lower LUMO energies and smaller band gaps than bent ones, resulting in different reactivity patterns. These results provide a benchmark dataset to guide further research in this rapidly emerging area. 相似文献
The chiral thallium amidinium cyclopentadiene-N-ylide complexes [C5(CO2Me)4{ArNC(Ar")NAr}]Tl were synthesized and structurally characterized by X-ray diffraction analysis and NMR spectroscopy. In these complexes, an unusual mode of coordination of the thallium atom was found, viz., the thallium atom is coordinated by both the side-chain nitrogen atom (N—Tl, 2.833(6) ) and the system of the cyclopentadienyl ring (Tl—Cp, 2.887(4) 5-bonding). 相似文献
The polyfunctional (H)PNX (X = O or N) ligands 1 and 2 react with [Rh(CO)2Cl]2 to give the corresponding chloro carbonyl complexes {Rh[κ2-(H)PN](CO)Cl} (1a and 2a), where the neutral ligands coordinate in a κ2-PN bidentate fashion, the square planar coordination being completed by the CO trans to N and the chloride trans to P. In chloroform solution 1a maintains its original structure, while 2a partially transforms into the cationic species {Rh[κ3-(H)PNO](CO)}Cl. The chloroform solutions of 1a and 2a react with AgPF6 to give the purely cationic species {Rh[κ3-(H)PNO](CO)}PF6 ([1a]+ and [2a]+), while addition of Et3N originates the neutral species {Rh[κ3-PNN′](CO)} (1b and 2b). All the complexes have been characterized by microanalysis, IR, 1H NMR as well as 31P{1H} NMR spectroscopy. The X-ray structures of ligand 1 and complex 1b are also reported. 相似文献
A synthetic route to tetradentate chiral N(4) ligands has been developed with the aim to study the potential of corresponding iron and manganese complexes as catalysts for enantioselective epoxidation. These ligands, which contain two oxazoline rings and two trialkylamino groups as coordinating units, are readily prepared in enantiomerically pure form by the reaction of chiral 2-chloromethyloxazolines with achiral N,N'-dimethylethane-1,2-diamine or chiral (R,R)-N,N'-dimethylcyclohexane-1,2-diamine. The ligands derived from N,N'-dimethylethane-1,2-diamine reacted with anhydrous metal halides MnCl(2) and FeCl(2) in a stereoselective manner to give octahedral mononuclear complexes that have the general formula Delta-[(L)MCl(2)]. In contrast, the ligands derived from N,N'-dimethylcyclohexane-1,2-diamine formed complexes with different coordination modes depending on the diastereomer employed: in one case the metal ion was found to be pentacoordinate, in the other case a hexacoordinated complex was observed. The structure of a series of Fe and Mn complexes was determined by X-ray analysis. The coordination chemistry of these ligands was further studied by X-ray and NMR analyses of the diamagnetic isostructural complexes [(L)ZnCl(2)]. Analogous ionic complexes, which were prepared by removing chloride with silver trifluoromethanesulfonate or hexafluoroantimonate, were tested as catalysts for the epoxidation of olefins. 相似文献
The ability of substituted carbazol‐9‐yl systems to ligate in σ fashion through the amido N‐donor, or to adopt alternative coordination modes through the π system of the central five‐membered ring, can be tuned by systematic variation in the steric demands of substituents in the 1‐ and 8‐positions. The differing affinities of the two modes of coordination for hard and soft metal centres can be shown to influence not only cation selectivity, but also the redox properties of the metal centre. Thus, the highly sterically sterically demanding 1,3,6,8‐tetra‐tert‐butylcarbazolyl ligand can be used to generate the structurally characterised amido‐indium(I) complex, [{(tBu4carb)In}n], (together with its isostructural thallium counterpart) in which the metal centre interacts with the central pyrrolyl ring in η3 fashion [d(In? N)=2.679(3) Å; d(In? C)=2.819(3), 2.899(3) Å]. By contrast, the smaller 3,6‐di‐tert‐butylcarbazolyl system is less able to restrict the metal centre from binding at the anionic nitrogen donor in the plane of the carbazolyl ligand (i.e. in σ fashion). Analogous chemistry with InI precursors therefore leads to disproportionation to the much harder InII [and In0], and the formation of the mixed‐valence product, [In2{In2(tBu2carb)6}], a homoleptic molecular [In4(NR2)6] system. This chemistry reveals a flexibility of ligation for carbazolyl systems that contrasts markedly with that of the similarly sterically encumbered terphenyl ligand family. 相似文献
Fit for a king : Cationic complexes of GeII can be prepared by using crown ethers to stabilize and protect the germanium center. Three different crown ethers were employed: [12]crown‐4 (see structure, Ge teal, O red, C gray), [15]crown‐5, and [18]crown‐6. The structures of the cationic complexes depend on the cavity size of the crown ether and on the substituent on germanium.
A crown for germanium : Neutral aza‐ and oxamacrocycles enable stabilization of halide‐free germanium(II) dications (see structure, Ge teal, N blue, C gray). The resulting structures show a marked dependence upon the denticity, donor type, and ring size of the macrocycle.
A series of spirooxazine-containing 2,2'-bipyridine ligands and their rhenium(i) tricarbonyl complexes has been designed and synthesized, and their photophysical, photochromic and electrochemical properties have been studied. The X-ray crystal structures of two of the complexes have been determined. Detailed studies showed that the emission properties of the complexes could readily be switched through photochromic reactions. 相似文献
Manganese alkyl complexes stabilised by 2,6-bis(N,N'-2,6-diisopropyl-phenyl)acetaldiminopyridine ((iPr)BIP) have been selectively prepared by reacting suitable alkylmanganese(II) precursors, such as homoleptic dialkyls [(MnR(2))(n)] or the corresponding THF adducts [{MnR(2)(thf)}(2)] with the mentioned ligand. For R=CH(2)CMe(2)Ph or CH(2)Ph, formally Mn(I) derivatives are produced, in which one of the two R groups migrates to the 4-position of the central pyridine ring in the (iPr)BIP ligand. In contrast, a true dialkyl complex [MnR(2)((iPr)BIP)] can be isolated for R=CH(2)SiMe(3). In solution, this compound slowly evolves to the corresponding Mn(I) monoalkyl derivative. A detailed study of this reaction provides insights on its mechanism, showing that it proceeds through successive alkyl migrations, followed by spontaneous dehydrogenation. Protonation of [Mn(CH(2)SiMe(3))(2)((iPr)BIP)] with the pyridinium salt [H(Py)(2)][BAr'(4)] (Ar'=3,5-C(6)H(3)(CF(3))(2)) leads to the cationic species [Mn(CH(2)SiMe(3))(Py)((iPr)BIP)](+). Alternatively, the same complex can be produced by reaction of the pyridine complex [{Mn(CH(2)SiMe(3))(2)(Py)}(2)] with the protonated ligand salt [H(iPr)BIP](+)[BAr'(4)](-). This last reaction allows the synthesis of analogous cationic alkylmanganese(II) derivatives, when precursors of type [MnR(2)((iPr)BIP)] are not available. Treatment of these neutral and cationic (iPr)BIP alkylmanganese derivatives with a range of typical co-catalysts (modified methylaluminoxane (MMAO), B(C(6)F(5))(3), trimethyl or triisobutylaluminum) does not lead to active ethylene polymerisation catalysts. 相似文献
Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HLMe, HLPh, HLMe3 and HLPh3, [HL = N-(2-pyridylmethyl)acetamide; HLMe = N-(2-pyridylmethyl)propionamide; HLPh = 2-phenyl-N-(2-pyridylmethyl)acetamide; HLMe3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HLPh3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)2(OTf)2] (1), [Cu(HLMe)2](ClO4)2 (2), [Cu(HL)2Cl]2[CuCl4] (3), [Cu(HLMe3)2(THF)](OTf)2 (4), [Cu(HLMe3)2(H2O)](ClO4)2 (5a and 5b), [Cu(HLPh3)2(H2O)](ClO4)2 (6), [Cu(HL)(2,2′-bipy)(H2O)](ClO4)2 (7), and [Cu(HLPh)(2,2′-bipy)(H2O)](ClO4)2 (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures. 相似文献
The Crystal Structure of (N,N-Diethyl-N′-benzoylselenoureato)thallium(I) . Tl(C12H15N2OSe) exists in a dimeric form and crystallizes in the triclinic space group P-1. The cell parameters are a = 6.501(6), b = 9.901(7), c = 12.233(9) Å, α = 91.59(2), β = 80.11(6), γ = 85.28(5)° and Z = 2. The structure was solved with Patterson and direct methods and was refined to a final R-value of 5.30%. Two complex molecules are connected by Tl? Se bonds to form a planar four membered ring with diagonally arranged Tl and Se atoms. The considerably bended chelate rings are nearly at right angle to the central four membered ring. The Tl? Se bond lengths are 3.105(3) and 3.118(3) Å, the Tl? O bond length is 2.532(9) Å. 相似文献