Yttrium bis(alkyl) and bis(amido) complexes bearing N,O multidentate ligands. Synthesis and catalytic activity towards ring‐opening polymerization of L‐lactide

Methoxy‐modified β‐diimines HL ¹ and HL ² reacted with Y(CH₂SiMe₃)₃(THF)₂ to afford the corresponding bis(alkyl)s [L¹Y(CH₂SiMe₃)₂] ( 1 ) and [L²Y(CH₂SiMe₃)₂] ( 2 ), respectively. Amination of 1 with 2,6‐diisopropyl aniline gave the bis(amido) counterpart [L¹Y{N(H)(2,6‐iPr₂? C₆H₃)}₂] ( 3 ), selectively. Treatment of Y(CH₂SiMe₃)₃(THF)₂ with methoxy‐modified anilido imine HL ³ yielded bis(alkyl) complex [L³Y(CH₂SiMe₃)₂(THF)] ( 4 ) that sequentially reacted with 2,6‐diisopropyl aniline to give the bis(amido) analogue [L³Y{N(H)(2,6‐iPr₂? C₆H₃)}₂] ( 5 ). Complex 2 was “base‐free” monomer, in which the tetradentate β‐diiminato ligand was meridional with the two alkyl species locating above and below it, generating tetragonal bipyramidal core about the metal center. Complex 3 was asymmetric monomer containing trigonal bipyramidal core with trans‐arrangement of the amido ligands. In contrast, the two cis‐located alkyl species in complex 4 were endo and exo towards the O,N,N tridentate anilido‐imido moiety. The bis(amido) complex 5 was confirmed to be structural analogue to 4 albeit without THF coordination. All these yttrium complexes are highly active initiators for the ring‐opening polymerization of L ‐LA at room temperature. The catalytic activity of the complexes and their “single‐site” or “double‐site” behavior depend on the ligand framework and the geometry of the alkyl (amido) species in the corresponding complexes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5662–5672, 2007     

Platinum complexes of oxopurines: cis‐bis(theophyllinato‐N7)bis(triphenylphosphine)platinum(II) and cis‐chloro(theobrominato‐N1)bis(triphenylphosphine)platinum(II) ethanol hemisolvate

The syntheses and structures of two mixed‐ligand complexes of platinum(II) with deprotonated oxopurine bases and tri­phenyl­phosphine are reported, namely the theophyllinate complex cis‐bis(1,2,3,6‐tetra­hydro‐1,3‐di­methyl­purine‐2,6‐dionato‐κN⁷)­bis(tri­phenyl­phosphine‐κP)­platinum(II), [Pt(C₇H₇N₄O₂)₂(C₁₈H₁₅P)₂], (I), and the theobrominate complex cis‐chloro(1,2,3,6‐tetrahydro‐3,7‐dimethylpurine‐2,6‐dionato‐κN¹)­bis(tri­phenyl­phosphine‐κP)­platinum(II) ethanol hemisolvate, [PtCl(C₇H₇N₄O₂)(C₁₈H₁₅P)₂]·0.5C₂H₅OH, (II). In (I), the coordination geometry of Pt is square planar, formed by the two coordinating N atoms of the theophyl­linate anions in a cis arrangement and two P atoms from the tri­phenyl­phosphine groups. In (II), there are two crystallographically independent mol­ecules. They both exhibit a square‐planar coordination geometry around Pt involving one Cl atom, the coordinating N atom of the theobrominate anion and two P atoms from the tri­phenyl­phosphine groups. The two tri­phenyl­phosphine groups are arranged in a cis configuration in both structures. The heterocyclic rings are rotated with respect to the coordination plane of the metal by 82.99 (8) and 88.09 (8)° in complex (I), and by 85.91 (16) and 88.14 (18)° in complex (II). Both structures are stabilized by intramolecular stacking interactions involving the purine rings and the phenyl rings of adjacent tri­phenyl­phosphine moieties.     

Synthesis of Organoplatinum Poly(dendrimer)s: Pronounced Effect of Size and Geometry of Small Organoplatinum Linkers on the Copolymerization Efficiency with Bifunctional Dendritic Macromonomers

The copolymerizations of two series of surface functionalized bis(acetylene) G1–G3 dendrimers, one ( S ‐ Gn ) having a structural rigid skeleton and the other ( L ‐ Gn ) a relatively more flexible architecture, with two platinum linkers, cis‐[(Et₂PCH₂CH₂PEt₂)PtCl₂] ( 2 ) and [Cl(Et₃P)₂Pt‐C?C‐p‐C₆H₄‐]₂ ( 3 ) were investigated. For both series of dendrimers, only linear and/or cyclic oligomers were formed when the cis‐platinum linker 2 was used. However, high molecular weight (100–200 kD) organoplatinum poly(dendrimer)s were obtained from both series when the elongated linear rod‐liked platinum linker 3 was employed and the formation of cyclic oligomers was greatly suppressed for both the structural rigid S ‐ Gn and the structural flexible L ‐ Gn series. These results are in sharp contrast to our earlier findings (S.‐Y. Cheung, H.‐F. Chow, T. Ngai, X. Wei, Chem. Eur. J. 2009 , 15, 2278–2288) obtained by using a shorter linear platinum linker trans‐[Pt(PEt₃)₂Cl₂] ( 1 ), where a larger amount of cyclic oligomers was formed from the structural flexible L ‐ Gn dendrimers. A model was proposed to rationalize how the geometry and size of the platinum linker could control the copolymerization behaviours of these dendritic macromonomers.     

Incorporation of Boron into Uranium Metallacycles: Synthesis,Structure, and Reactivity of Boron-Containing Uranacycles Derived from Bis(alkynyl)boranes

The reaction of uranacyclopropene complex (C₅Me₅)₂U[η²-1,2-C₂(SiMe₃)₂] with B-aryl bis(alkynyl)borane PhB(C≡CPh)₂ led to the first six-membered uranium metallaboracycle, while the reaction with B-amino bis(alkynyl)borane (Me₃Si)₂NB(C≡CPh)₂ afforded an unexpected uranaborabicyclo[2.2.0] complex via [2+2] cycloaddition. The reaction with CuCl revealed the non-innocent property of the rearranged bis(alkynyl)boron species towards oxidant. The reactions with isocyanide DippNC: (Dipp=2,6-iPr₂-C₆H₃) and isocyanate tBuNCO afforded the novel uranaborabicyclo[3.2.0] complexes. All new complexes have been structurally characterized. DFT calculations were performed to provide more insights into the electronic structures and the reaction mechanism.     

Platinum(II) Metallomesogens: New External‐Stimuli‐Responsive Photoluminescence Materials

New dicatenar isoquinoline‐functionalized pyrazoles, [Hpz^R(n,n)iq] (R(n,n)=C₆H₃(OC_nH_2n+1)₂; n=4, 6, 8, 10, 12, 14, 16, 18), have been strategically designed and synthesized to induce mesomorphic and luminescence properties into the corresponding bis(isoquinolinylpyrazolate)platinum(II) complexes [Pt(pz^R(n,n)iq)₂]. Thermal studies reveal that all platinum(II) compounds exhibit columnar mesophases over an exceptionally wide temperature range, above 300 °C in most cases. The photophysical behavior was also investigated in solution and in the solid state. As a consequence of the formation of Pt???Pt interactions, the weak greenish emission of the platinum derivatives turns bright orange in the mesophase. Additionally, the complexes are sensitive to a great variety of external inputs, such as temperature, mechanical grinding, pressure, solvents, and vapors. On this basis, they are used as dopant agents of a polyvinylpyrrolidone or poly(methyl methacrylate) polymer matrix to achieve stimuli‐responsive thin films.     

Reactivity of Cationic Agostic and Carbene Structures Derived from Platinum(II) Metallacycles

This paper describes the formation of new platinacyclic complexes derived from the phosphine ligands PiPr₂Xyl, PMeXyl₂, and PMe₂Ar (Xyl=2,6‐Me₂C₆H₃ and Ar=2,6‐(2,6‐Me₂C₆H₃)₂‐C₆H₃) as well as reactivity studies of the trans‐[Pt(C^P)₂] bis‐metallacyclic complex 1 a derived from PiPr₂Xyl. Protonation of compound 1 a with [H(OEt₂)₂][BAr_F] (BAr_F=B[3,5‐(CF₃)₂C₆H₃]₄) forms a cationic δ‐agostic structure 4 a , whereas α‐hydride abstraction employing [Ph₃C][PF₆] produces a cationic platinum carbene trans‐[Pt{PiPr₂(2,6‐CH(Me)C₆H₃}{PiPr₂(2,6‐CH₂(Me)C₆H₃}][PF₆] ( 8 ). Compounds 4 a and 8 react with H₂ to yield the same 1:3 equilibrium mixture of 4 a and trans‐[PtH(PiPr₂Xyl)₂][BAr_F] ( 6 ), in which one of the phosphine ligands participates in a δ‐agostic interaction. DFT calculations reveal that H₂ activation by 8 occurs at the highly electrophilic alkylidene terminus with no participation of the metal. The two compounds 4 a and 8 experience C–C coupling reactions of a different nature. Thus, 4 a gives rise to complex trans‐[PtH{(E)‐1,2‐bis(2‐(PiPr₂)‐3‐MeC₆H₃)CH?CH}] ( 7 ) that contains a tridentate diphosphine–alkene ligand, through agostic C?H oxidative cleavage and C–C reductive coupling steps, whereas the C–C coupling reaction in 8 involves classical migratory insertion of its [Pt?CH] and [Pt?CH₂] bonds promoted by platinum coordination of CO or CNXyl. The mechanisms of the C?C bond‐forming reactions have also been investigated by computational methods.     

Synthesis,Structural Characterization and Reactivity of a Bis(phosphine)(silyl) Platinum(II) Complex

Treatment of 1,2‐C₆H₄(SiH₃)(SiH₃) ( 1 ) with Pt(dmpe)(PEt₃)₂ (dmpe=Me₂PCH₂CH₂PMe₂) in the ratio of 1:1 leads to the complex {1,2‐C₆H₄(SiH₂)(SiH₂)}Pt^II (dmpe) ( 2 ), which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra‐alkoxy substituted silyl platinum(II) compound ( 3 ). Compounds 2 and 3 are the very rare examples of silyl transition‐metal complexes derived from this chelating hydrosilane ligand. To the best of our knowledge, there are only 6 examples of silyl metal complexes prepared from this ligand with such structural features registered in the Cambridge Structural Database, among them, only one silyl platinum(II) compound is presented. The structures of complexes 2 and 3 were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X‐ray analysis.     

Syntheses and Structures of Terminal Arylalumylene Complexes

Terminal arylalumylene complexes of platinum [Ar‐Al‐Pt(PCy₃)₂] (Ar=2,6‐[CH(SiMe₃)₂]₂C₆H₃ (Bbp) or 2,6‐[CH(SiMe₃)₂]₂‐4‐(tBu)C₆H₂ (Tbb)) have been synthesized either by the reaction of a dialumene–benzene adduct with [Pt(PCy₃)₂], or by the reduction of 1,2‐dibromodialumanes Ar(Br)Al‐Al(Br)Ar in the presence of [Pt(PCy₃)₂]. X‐Ray crystallographic analysis reveals that the Al? Pt bond lengths of these arylalumylene complexes are shorter than the previously reported shortest Al? Pt distance. DFT calculations suggest that the Al? Pt bonds in the arylalumylene complexes have a significantly high electrostatic character.     

Hexanuclear Pt complexes composed of two cyclic triplatinum units connected with 1,4-diphenylene and 1,1′-ferrocenylene spacer

1,4-Bis(dimethylsilyl)benzene reacted with [Pt₃H(PEt₃)₃(μ-PPh₂)₃] at room temperature to yield trinuclear Pt complex [Pt₃(SiMe₂C₆H₄SiMe₂H)(PEt₃)₂(μ-PPh₂)₃] (1a). Heating a solution containing an equimolar mixture of [Pt₃H(PEt₃)₃(μ-PPh₂)₃] and 1a at 60 °C produced a hexanuclear Pt complex [(PEt₃)₂(μ-PPh₂)₃Pt₃(SiMe₂C₆H₄SiMe₂)Pt₃(PEt₃)₂(μ-PPh₂)₃] (2a). Complex 1a was characterized by X-ray crystallography and NMR spectroscopy, while the structure of 2a was determined by X-ray crystallography of single crystals containing 2a and [Pt₃H₂(PEt₃)₂(μ-PPh₂)₄] in 1:1 ratio. [Pt₃(SiMe₂fcSiMe₂H)(PEt₃)₂(μ-PPh₂)₃] (fc = Fe(η⁵-C₅H₄)₂) (1b) and [(PEt₃)₂(μ-PPh₂)₃Pt₃(SiMe₂fcSiMe₂)Pt₃(PEt₃)₂(μ-PPh₂)₃] (2b) were obtained similarly from the reactions of 1,1′-bis(dimethylsilyl)ferrocene with [Pt₃H(PEt₃)₃(μ-PPh₂)₃] and characterized by NMR spectroscopy and elemental analyses.     

Tetraazadibora[3, 3]paracyclophane

Starting from the para‐phenylenediamine derivative HN(SiMe₃)‐C₆H₄‐NH(SiMe₃), a lithiation and subsequent borylation give [(MeO)₂B]N(SiMe₃)‐C₆H₄‐N(SiMe₃)[B(OMe)₂] ( 1 ), the hydridation of which yields Li₂[(H₃B)N(SiMe₃)‐C₆H₄‐N(SiMe₃)(BH₃)] ( 2 ). Applying ZrCl₄ upon 2 initiates a condensation to give the title compound [‐N(SiMe₃)‐p‐C₆H₄‐N(SiMe₃)‐BH‐]₂, a hetero[3, 3]paracyclophane with two N‐B‐N chains that connect the para‐phenylene units. The product 3 crystallizes in the orthorhombic space group P2₁2₁2₁.     

Hemilability and structural considerations in complexes of platinum(II) comprising bis(diphenylphosphanyl)methane monoxide,monosulfide, and monoselenide

The structure of a platinum(II) complex containing (R)-(dimethylamino)ethylnapthyl and bis(diphenylphosphanyl)methane monosulfide ligands, namely, {(R)-1-[1-(dimethylamino)ethyl]napthyl-κ²N,C²}[(diphenylphosphanylmethyl)diphenylphosphine sulfide-κ²P,S]platinum(II) hexafluoridoantimonate dichloromethane monosolvate, [Pt(C₁₄H₁₆N)(C₂₅H₂₂P₂S)][SbF₆]·CH₂Cl₂, was determined. The structural features are compared with analogous platinum bis(diphenylphosphanyl)methane monoxide [dppm(O)] and bis(diphenylphosphanyl)methane monoselenide [dppm(Se)] complexes in relation to their potential hemilability and stereochemical nonrigidity.     

Rare‐Earth‐Metal–Hydrocarbyl Complexes Bearing Linked Cyclopentadienyl or Fluorenyl Ligands: Synthesis,Catalyzed Styrene Polymerization,and Structure–Reactivity Relationship

A series of rare‐earth‐metal–hydrocarbyl complexes bearing N‐type functionalized cyclopentadienyl (Cp) and fluorenyl (Flu) ligands were facilely synthesized. Treatment of [Y(CH₂SiMe₃)₃(thf)₂] with equimolar amount of the electron‐donating aminophenyl‐Cp ligand C₅Me₄H‐C₆H₄‐o‐NMe₂ afforded the corresponding binuclear monoalkyl complex [({C₅Me₄‐C₆H₄‐o‐NMe(μ‐CH₂)}Y{CH₂SiMe₃})₂] ( 1 a ) via alkyl abstraction and C? H activation of the NMe₂ group. The lutetium bis(allyl) complex [(C₅Me₄‐C₆H₄‐o‐NMe₂)Lu(η³‐C₃H₅)₂] ( 2 b ), which contained an electron‐donating aminophenyl‐Cp ligand, was isolated from the sequential metathesis reactions of LuCl₃ with (C₅Me₄‐C₆H₄‐o‐NMe₂)Li (1 equiv) and C₃H₅MgCl (2 equiv). Following a similar procedure, the yttrium‐ and scandium–bis(allyl) complexes, [(C₅Me₄‐C₅H₄N)Ln(η³‐C₃H₅)₂] (Ln=Y ( 3 a ), Sc ( 3 b )), which also contained electron‐withdrawing pyridyl‐Cp ligands, were also obtained selectively. Deprotonation of the bulky pyridyl‐Flu ligand (C₁₃H₉‐C₅H₄N) by [Ln(CH₂SiMe₃)₃(thf)₂] generated the rare‐earth‐metal–dialkyl complexes, [(η³‐C₁₃H₈‐C₅H₄N)Ln(CH₂SiMe₃)₂(thf)] (Ln=Y ( 4 a ), Sc ( 4 b ), Lu ( 4 c )), in which an unusual asymmetric η³‐allyl bonding mode of Flu moiety was observed. Switching to the bidentate yttrium–trisalkyl complex [Y(CH₂C₆H₄‐o‐NMe₂)₃], the same reaction conditions afforded the corresponding yttrium bis(aminobenzyl) complex [(η³‐C₁₃H₈‐C₅H₄N)Y(CH₂C₆H₄‐o‐NMe₂)₂] ( 5 ). Complexes 1 – 5 were fully characterized by ¹H and ¹³C NMR and X‐ray spectroscopy, and by elemental analysis. In the presence of both [Ph₃C][B(C₆F₅)₄] and AliBu₃, the electron‐donating aminophenyl‐Cp‐based complexes 1 and 2 did not show any activity towards styrene polymerization. In striking contrast, upon activation with [Ph₃C][B(C₆F₅)₄] only, the electron‐withdrawing pyridyl‐Cp‐based complexes 3 , in particular scandium complex 3 b , exhibited outstanding activitiy to give perfectly syndiotactic (rrrr >99 %) polystyrene, whereas their bulky pyridyl‐Flu analogues ( 4 and 5 ) in combination with [Ph₃C][B(C₆F₅)₄] and AliBu₃ displayed much‐lower activity to afford syndiotactic‐enriched polystyrene.     

Luminescent Amphiphilic 2,6‐Bis(1‐alkylpyrazol‐3‐yl)pyridyl Platinum(II) Complexes: Synthesis,Characterization, Electrochemical,Photophysical, and Langmuir–Blodgett Film Formation Studies

Two series of novel platinum(II) 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridyl (N5Cn) complexes, [Pt(N5Cn)Cl][X] ( 1 – 9 ) and [Pt(N5Cn)(C?CR)][X] ( 10 – 13 ) (X=trifluoromethanesulfonate (OTf) or PF₆; R=C₆H₅, C₆H₄‐p‐CF₃ and C₆H₄‐p‐N(C₆H₅)₂), with various chain lengths of the alkyl groups on the nitrogen atom of the pyrazolyl units have been successfully synthesized and characterized. Their electrochemical and photophysical properties have been studied. Some of their molecular structures have also been determined by X‐ray crystallography. Two amphiphilic platinum(II) 2,6‐bis(1‐tetradecylpyrazol‐3‐yl)pyridyl (N5C14) complexes, [Pt(N5C14)Cl]PF₆ ( 7 ) and [Pt(N5C14)(C?CC₆H₅)]PF₆ ( 13 ), were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air–water interface. The characterization of such LB films has been investigated by the study of their surface pressure–area (π–A) isotherms, UV/Vis spectroscopy, XRD, X‐ray photoelectron spectroscopy (XPS), FTIR, and polarized IR spectroscopy. The luminescence property of 13 in LB films has also been studied.     

Synthesis and Structures of ansa‐Titanocene Complexes with Diatomic Bridging Units for Overall Water Splitting

The synthesis of a series of ansa‐titanocene dichlorides [Cp′₂TiCl₂] (Cp′=bridged η⁵‐tetramethylcyclopentadienyl) and the corresponding titanocene bis(trimethylsilyl)acetylene complexes [Cp′₂Ti(η²‐Me₃SiC₂SiMe₃)] is described. The ethanediyl‐bridged complexes [C₂H₄(C₅Me₄)₂TiCl₂] ( 2 ‐Cl₂) and [C₂H₄(C₅Me₄)₂Ti(η²‐Me₃SiC₂SiMe₃)] ( 2‐ btmsa; btmsa=η²‐Me₃SiC₂SiMe₃) can be obtained from the hitherto unknown calcocenophane complex [C₂H₄(C₅Me₄)₂Ca(THF)₂] ( 1 ). Furthermore, a heterodiatomic bridging unit containing both, a dimethylsilyl and a methylene group was introduced to yield the ansa‐titanocene dichloride [Me₂SiCH₂(C₅Me₄)₂TiCl₂] ( 3 ‐Cl₂) and the bis(trimethylsilyl)acetylene complex [Me₂SiCH₂(C₅Me₄)₂Ti(η²‐Me₃SiC₂SiMe₃)] ( 3 ‐btmsa). Besides, tetramethyldisilyl‐ and dimethylsilyl‐bridged metallocene complexes (structural motif 4 and 5 , respectively) were prepared. All ansa‐titanocene alkyne complexes were reacted with stoichiometric amounts of water; the hydrolysis products were isolated as model complexes for the investigation of the elemental steps of overall water splitting. Compounds 1 , 2 ‐btmsa, 2 ‐(OH)₂, 3 ‐Cl₂, 3 ‐btmsa, 4 ‐(OH)₂, 3 ‐alkenyl and 5 ‐alkenyl were characterised by X‐ray diffraction analysis.     

Synthesis and Characterization of m‐Terphenyl (1,3‐Diphenylbenzene) Compounds Containing Trifluoromethyl Groups

The bis(silyl)triazene compound 2,6‐(Me₃Si)₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 4 ) was synthesized by double lithiation/silylation of 2,6‐Br₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 1 ). Furthermore, 2,6‐bis[3,5‐(CF₃)₂‐C₆H₃]‐4‐Me‐C₆H₂‐1‐(N?N? NC₄H₈)C₆H₂ derivative 6 can be easily synthesized by a C,C‐bond formation reaction of 1 with the corresponding aryl‐Grignard reagent, i.e., 3,5‐bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I₂ afforded in good yields novel phenyl derivatives, 2,6‐(Me₃Si)₂‐4‐MeC₆H₂? I and 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]‐4‐MeC₆H₂? I ( 5 and 7 , resp.). On the other hand, the analogous m‐terphenyl 1,3‐diphenylbenzene compound 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]C₆H₃? I ( 8 ) could be obtained in moderate yield from the reaction of (2,6‐dichlorophenyl)lithium and 2 equiv. of aryl‐Grignard reagent, followed by the reaction with I₂. Different attempts to introduce the ^tBu (Me₃C) or neophyl (PhC(Me)₂CH₂) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single‐crystal X‐ray diffraction measurements.     

Solvent effect on the stability and properties of platinum-substituted borirene and boryl isomers: The polarizable continuum model

The structure and properties of platinum borirene complex trans-[Cl(PMe₃)₂Pt{μ-BN(SiMe₃)₂C=C}Ph] and its isomer the platinum boryl complex trans–[Cl(PMe₃)₂PtBN(SiMe₃)₂C≡CPh] were investigated theoretically. The solvent effect on the stability, structural parameters, frontier orbital energies, HOMO–LUMO gaps, and hardness of isomers was investigated using the polarizable continuum model (PCM). It was found that borirene isomer is the most stable isomer in the gas phase and solvent. The calculated results show that the presence of solvent reduces the frontier orbital energy of the studied molecules. Geometries obtained from calculations were used to perform NBO analysis.     

Dimeric copper(II) 3,3‐dimethyl­butyrate adducts with ethanol, 2‐methylpyridine, 3‐methylpyridine, 4‐methylpyridine and 3,3‐dimethylbutyric acid

In the crystals of the five title compounds, tetrakis‐(μ‐3,3‐dimethylbutyrato‐O:O′)bis(ethanol‐O)dicopper(II)–ethanol (1/2), [Cu₂(C₆H₁₁O₂)₄(C₂H₆O)₂]·2C₂H₆O, (I), tetrakis(μ‐3,3‐dimethylbutyrato‐O:O′)bis(2‐methylpyridine‐N)di­copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (II), tetrakis‐(μ‐3,3‐dimethylbutyrato‐O:O′)bis(3‐methylpyridine‐N)di‐copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (III), tetrakis‐(μ‐3,3‐dimethylbutyrato‐O:O′)bis(4‐methylpyridine‐N)di‐copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (IV), and tetrakis‐(μ‐3,3‐dimethylbutyrato‐O:O′)bis(3,3‐dimethylbutyric acid‐O)dicopper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₁₂O₂)₂], (V), the di­nuclear Cu^II complexes all have centrosymmetric cage structures and (IV) has two independent molecules. The Cu?Cu separations are: (I) 2.602 (3) Å, (II) 2.666 (3) Å, (III) 2.640 (2) Å, (IV) 2.638 (4) Å and (V) 2.599 (1) Å.     

9,9-二己基芴基四乙炔基聚炔铂的合成及发光性质

Soluble platinum(Ⅱ)polyyne polymers trans-{Pt-[P(C_4H_8N)_3]_2(C≡C)_2R(C≡C)_(2-)}_n and trans-{Pt-[P(C_4-H_3O)_3]_2(C≡C)_2R(C≡C)_(2-)}_n(R=9,9-dihexylfluorene-2,7-diyl)have been prepared in good yields by CuI-catalyzedpolymerization involving the dehydrohalogenating coupling of trans-{PtCl_2[P(C_4H_8N)_3]_2} and trans-{PtCl_2[P-(C_4H_3O)_3]_2} with H(C≡C)_2R(C≡C)_2H,respectively.We report the optical spectroscopy of these polyplatinaynes.The influence of the heavy metal atom in these metal alkynyl systems on the intersystem crossing rate and the spa-tial extent of lowest singlet and triplet excitons was systematically characterized.Our investigations indicate that theorganic triplet emissions can be harvested by the heavy-atom effect which enables efficient intersystem crossingfrom the S_1 singlet excited state to the T_1 triplet excited state.     

Two zinc(II) coordination complexes based on an asymmetric multidentate ligand: syntheses,structures, selective fluorescence sensing of iron(III) ions and thermal analyses

The rational selection of ligands is vitally important in the construction of coordination complexes. Two novel Zn^II complexes, namely bis(acetato‐κO)bis[1‐(1H‐benzotriazol‐1‐ylmethyl)‐2‐propyl‐1H‐imidazole‐κN³]zinc(II) monohydrate, [Zn(C₁₃H₁₅N₅)₂(C₂H₃O₂)₂]·H₂O, ( 1 ), and bis(azido‐κN¹)bis[1‐(1H‐benzotriazol‐1‐ylmethyl)‐2‐propyl‐1H‐imidazole‐κN³]zinc(II), [Zn(C₁₃H₁₅N₅)₂(N₃)₂], ( 2 ), constructed from the asymmetric multidentate imidazole ligand, have been synthesized under mild conditions and characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction analysis. Both complexes exhibit a three‐dimensional supramolecular network directed by different intermolecular interactions between discrete mononuclear units. The complexes were also investigated by fluorescence and thermal analyses. The experimental results show that ( 1 ) is a promising fluorescence sensor for detecting Fe³⁺ ions and ( 2 ) is effective as an accelerator of the thermal decomposition of ammonium perchlorate.     

C−H and C−F Bond Activation Reactions of Fluorinated Propenes at Rhodium: Distinctive Reactivity of the Refrigerant HFO‐1234yf

The reaction of [Rh(H)(PEt₃)₃] ( 1 ) with the refrigerant HFO‐1234yf (2,3,3,3‐tetrafluoropropene) affords an efficient route to obtain [Rh(F)(PEt₃)₃] ( 3 ) by C?F bond activation. Catalytic hydrodefluorinations were achieved in the presence of the silane HSiPh₃. In the presence of a fluorosilane, 3 provides a C?H bond activation followed by a 1,2‐fluorine shift to produce [Rh{(E)‐C(CF₃)=CHF}(PEt₃)₃] ( 4 ). Similar rearrangements of HFO‐1234yf were observed at [Rh(E)(PEt₃)₃] [E=Bpin ( 6 ), C₇D₇ ( 8 ), Me ( 9 )]. The ability to favor C?H bond activation using 3 and fluorosilane is also demonstrated with 3,3,3‐trifluoropropene. Studies are supported by DFT calculations.