Alcohol oxidation reactions catalyzed by ruthenium–carbonyl complexes of thioarylazoimidazoles

Alcohols are oxidized by N‐methylmorpholine‐N‐oxide (NMO), Bu^tOOH and H₂O₂ to the corresponding aldehydes or ketones in the presence of catalyst, [RuH(CO)(PPh₃)₂(SRaaiNR′)]PF₆ ( 2 ) and [RuCl(CO)(PPh₃)(S_κRaaiNR′)]PF₆ ( 3 ) (SRaaiNR′ ( 1 ) = 1‐alkyl‐2‐{(o‐thioalkyl)phenylazo}imidazole, a bidentate N(imidazolyl) (N), N(azo) (N′) chelator and S_κRaaiNR′ is a tridentate N(imidazolyl) (N), N(azo) (N′), S_κ‐R is tridentate chelator; R and R′ are Me and Et). The single‐crystal X‐ray structures of [RuH(CO)(PPh₃)₂(SMeaaiNMe)]PF₆ ( 2a ) (SMeaaiNMe = 1‐methyl‐2‐{(o‐thioethyl)phenylazo}imidazole) and [RuH(CO)(PPh₃)₂(SEtaaiNEt)]PF₆ ( 2b ) (SEtaaiNEt = 1‐ethyl‐2‐{(o‐thioethyl)phenylazo}imidazole) show bidentate N,N′ chelation, while in [RuCl(CO)(PPh₃)(S_κEtaaiNEt)]PF₆ ( 3b ) the ligand S_κEtaaiNEt serves as tridentate N,N′,S chelator. The cyclic voltammogram shows Ru^III/Ru^II (~1.1 V) and Ru^IV/Ru^III (~1.7 V) couples of the complexes 2 while Ru^III/Ru^II (1.26 V) couple is observed only in 3 along with azo reductions in the potential window +2.0 to ?2.0 V. DFT computation has been used to explain the spectra and redox properties of the complexes. In the oxidation reaction NMO acts as best oxidant and [RuCl(CO)(PPh₃)(S_κRaaiNR′)](PF₆) ( 3 ) is the best catalyst. The formation of high‐valent Ru^IV=O species as a catalytic intermediate is proposed for the oxidation process. Copyright © 2014 John Wiley & Sons, Ltd.     

Homo‐ and Heterodinuclear Ir and Rh Imine‐functionalized Protic NHC Complexes: Synthetic,Structural Studies,and Tautomerization/Metallotropism Insights

The influence of the potentially chelating imino group of imine‐functionalized Ir and Rh imidazole complexes on the formation of functionalized protic N‐heterocyclic carbene (pNHC) complexes by tautomerization/metallotropism sequences was investigated. Chloride abstraction in [Ir(cod)Cl{C₃H₃N₂(DippN=CMe)‐κN3}] ( 1 a ) (cod=1,5‐cyclooctadiene, Dipp=2,6‐diisopropylphenyl) with TlPF₆ gave [Ir(cod){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 3 a ⁺[PF₆]^?). Plausible mechanisms for the tautomerization of complex 1 a to 3 a ⁺[PF₆]^? involving C2?H bond activation either in 1 a or in [Ir(cod){C₃H₃N₂(DippN=CMe)‐κN3}₂]⁺[PF₆]^? ( 6 a ⁺[PF₆]^?) were postulated. Addition of PR₃ to complex 3 a ⁺[PF₆]^? afforded the eighteen‐valence‐electron complexes [Ir(cod)(PR₃){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 7 a ⁺[PF₆]^? (R=Ph) and 7 b ⁺[PF₆]^? (R=Me)). In contrast to Ir, chloride abstraction from [Rh(cod)Cl{C₃H₃N₂(DippN=CMe)‐κN3}] ( 1 b ) at room temperature afforded [Rh(cod){C₃H₃N₂(DippN=CMe)‐κN3}₂]⁺[PF₆]^? ( 6 b ⁺[PF₆]^?) and [Rh(cod){C₃H₃N₂(DippN=CMe)‐κ²(C2,N_imine)}]⁺[PF₆]^? ( 3 b ⁺[PF₆]^?) (minor); the reaction yielded exclusively the latter product in toluene at 110 °C. Double metallation of the azole ring (at both the C2 and the N3 atom) was also achieved: [Ir₂(cod)₂Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 10 ) and the heterodinuclear complex [IrRh(cod)₂Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 12 ) were fully characterized. The structures of complexes 1 b , 3 b ⁺[PF₆]^?, 6 a ⁺[PF₆]^?, 7 a ⁺[PF₆]^?, [Ir(cod){C₃HN₂(DippN=CMe)(DippN=CH)(Me)‐κ²(N3,N_imine)}]⁺[PF₆]^? ( 9 ⁺[PF₆]^?), 10? Et₂O ? toluene, [Ir₂(CO)₄Cl{μ‐C₃H₂N₂(DippN=CMe)‐κ²(C2,N_imine),κN3}] ( 11 ), and 12? 2 THF were determined by X‐ray diffraction.     

Einkristalluntersuchungen an LiMF6 (M = Rh,Ir), Li2RhF6 und K2IrF6

Single Crystal Investigations on LiMF₆ (M = Rh, Ir), Li₂RhF₆, and K₂IrF₆ LiRhF₆, LiIrF₆, Li₂RhF₆, and K₂IrF₆ were obtained again, but for the first time investigated by single crystal X‐ray methods. Rubyred LiRhF₆ and yellow LiIrF₆ crystallize isostructural in the trigonal space group R3 – C²_3i (Nr. 148) with the lattice parameters LiRhF₆: a = 502.018(7) pm, c = 1355.88(3) pm, Z = 3 and d(Rh–F) = 185.5(1) pm; LiIrF₆: a = 506.148(4) pm, c = 1362.60(2) pm, Z = 3, d(Ir–F) = 187.5(3) pm (LiSbF₆‐Typ). Yellow Li₂RhF₆ crystallizes tetragonal in the space group P4₂/mnm – D¹⁴_4h (Nr. 136) with a = 463.880(8) pm, c = 905.57(2) pm, Z = 2 and d(Rh–F) = 190.3(4)–191.4(3) pm (Trirutil‐Typ). Yellow K₂IrF₆ crystallizes trigonal in the space group P3m1 – D³_3d (Nr. 164) with a = 578.88(7) pm, c = 465.06(5) pm, Z = 1 and d(Ir–F) = 194.0(6) pm, isotypic with K₂GeF₆.     

Einkristallstrukturuntersuchungen an hexagonalen Fluorperowskiten AMIIF3 (MII = Mg,Mn, Fe,Co, Ni)

Single Crystal Structural Studies at Hexagonal Fluoride Perovskites AM^IIF₃ (M^II = Mg, Mn, Fe, Co, Ni) At single crystals of nine fluoride phases AMF₃ the hexagonal perovskite structures were refined by X‐ray methods, of RbNiF₃ below T_C £ 145 K, too. The hexagonal 6 L type (P6₃/mmc, Z = 6) is found at: RbMgF₃ (a = 585.7(1); c = 1426.0(1) pm), CsMnF₃ (624.4(1); 1515.4(4) pm), CsFeF₃ (616.8(1); 1488.4(6) pm), Rb_0.63Cs_0.37CoF₃ (599.1(1); 1460.3(4) pm), RbNiF₃ (128 K: 582.6(1); 1426.4(6) pm), Cs₂BaLiNi₂F₉ (593.1(1); 1447.1(4) pm). Of the hexagonal‐rhombohedral 9 L type (R 3 m, Z = 9) are CsCoF₃ (620.1(1); 2264.0(7) pm) and yellow CsNiF₃ (614.7(1); 2235.3(6) pm), prepared at lower temperatures resp. under high pressure, whereas light green CsNiF₃ (625.5(1); 524.2(1) pm) belongs to the 2 L type (P6₃/mmc, Z = 2). The occurence of these structures and the interatomic distances observed, comparing also normal and high pressure phases, are discussed in connection with the tolerance factor.     

Synthese,Struktur und Eigenschaften der Komplexe [(Me2PhP)3Cl2Re≡N‐IrCl2(C5Me5)], [(Me2PhP)3Cl2Re≡N‐IrCl(COD)], [PPh4][O3Os≡N‐IrCl2(C5Me5)] und [PPh4][O3Os≡N‐IrCl(COD)] mit Nitridobrücken Re≡N‐Ir und Os≡N‐Ir

Synthesis and Crystal Structures of the Complexes [(Me₂PhP)₃Cl₂Re≡N‐IrCl₂(C₅Me₅)], [(Me₂PhP)₃Cl₂Re≡N‐IrCl(COD)], [PPh₄][O₃Os≡N‐IrCl₂(C₅Me₅)], and [PPh₄][O₃Os≡N‐IrCl(COD)] with Nitrido bridges Re≡N‐Ir and Os≡N‐Ir The heteronuclear complexes [(Me₂PhP)₃Cl₂Re≡N‐IrCl₂(C₅Me₅)] ( 1 ), [(Me₂PhP)₃Cl₂Re≡N‐IrCl(COD)] ( 2 ), [PPh₄][O₃Os≡N‐IrCl₂(C₅Me₅)] ( 3 ) and [PPh₄][O₃Os≡N‐IrCl(COD)] ( 4 ) were obtained by the reaction of the nitrido complexes [ReNCl₂(PMe₂Ph)₃] and [OsO₃N]^— with the iridium compounds [IrCl₂(C₅Me₅)]₂ and [IrCl(COD)]₂ in benzonitrile. 1 forms red crystals with the composition 1 ·C₆H₅CN in the monoclinic space group P2₁/c and a = 1264.7(2); b = 1945.3(2); c = 1835.4(1) pm, β = 90.35(1)°, Z = 4. The complex fragment [IrCl₂(C₅Me₅)] in the dinuclear complex is connected by an asymmetric nitrido bridge Re≡N‐Ir to the nitrido complex [ReNCl₂(PMe₂Ph)₃]. The nitrido bridge is characterized by a Re‐N‐Ir bond angle of 179.4(2)° and distances Re‐N = 170.9(4) pm and Ir‐N = 203.3(4) pm. 2 forms brownish red, triclinic crystals with the space group P1¯ and a = 1076.6(2), b = 1373.2(2), c = 1452.4(1) pm, α = 107.513(8), β = 101.843(9), γ = 110.04(1)°, Z = 2. The nitrido bridge to the complex fragment [IrCl(COD)] has a Re‐N‐Ir bond angle of 173, 8(4)° and distances Re‐N = 170, 4(8) pm and Ir‐N = 196, 2(8) pm. 3 crystallizes as monoclinic red crystals in the space group P2₁/n and a = 1449.9(2), b = 906.74(4), c = 2628.9(5) pm, β = 103.50(1)°, Z = 4. The nitrido bridge Os≡N‐Ir is slightly bent (Os‐N‐Ir = 165.0(3)°). The distances are Os‐N = 168.3(5) pm and Ir‐N = 201.9(5) pm. 4 forms dark brown, orthorhombic crystals with the space group P2₁2₁2₁ and a = 704.35(2), b = 1228.17(6), c = 3442.0(4) pm, Z = 4. The distances in the slightly bent nitrido bridge (Os‐N‐Ir = 161.8(4)°) are Os‐N = 169.3(7) pm und Ir‐N = 197.8(7) pm.     

Nickel-, Palladium- und Platinkomplexe funktionalisierter Makrocyclen. Die Kristallstrukturen von [Ni(py2-tasn)(H2O)](ClO4)2, [Pd(py2-tasn)](PF6)2 und [Pt(py2-tasn)](PF6)2. (py2-tasn=4,7-Bis(2-methylpyridyl)-1-thia-4,7-diazacyclononan

The Crystal Structures of [Ni(py₂-tasn)(H₂O)](ClO₄)₂, [Pd(py₂-tasn)](PF₆)₂, and [Pt(py₂-tasn)](PF₆)₂. (py₂-tasn=4,7-Bis(2-methylpyridyl)-1-thia-4,7-diazacyclononane) . The methylpyridyl functionalized macrocyclic ligand 4,7-Bis(2-methylpyridyl)-1-thia-4,7-diazacyclononane, py₂-tasn, forms the stable complexes [Ni(py₂-tasn)(H₂O)]²⁺, [Pd(py₂-tasn)]²⁺, and [Pt(py₂-tasn)]²⁺. They have been isolated in the solid state and characterized by X-ray crystal structure analyses. All five donor atoms of the ligand are bound to the respective metal atom. Ni^II is octahedrally coordinated, with the pyridyl groups in cis-positions, Pd^II and Pt^II are square pyramidally coordinated, with the thioether group in the apical position. The Pd (Pt)—S distances are 290.7(1) and 305.6(3) pm, respectively. Crystal data: [Ni(py₂-tasn)(H₂O)](ClO₄)₄, orthorhombic, space group P2₁2₁2₁, a=843.8(2), b=1 668.8(3), c=1 694.4(3) pm, Z=4, 2 444 unique data, R(R_w)=0.0825(0.0937); [Pd(py₂-tasn)](PF₆)₂: monoclinic, space group P2₁/c, a=694.7(1), b=1 906.5(4), c=1 980.9(4) pm, β=93,43°, Z=4, 5 429 unique data, R(R_w)=0.0351(0.0451); [Pt(py₂-tasn)](PF₆)₂: monoclinic, space group P2₁/n, a=1 080.1(2), b=1 175.0(2), c=2 075.6(4) pm, β=95.32(3)°, Z=4, 5 567 unique data, R(R_w)=0.0667(0.0845).     

Reactivity of ortho‐Substituted Aryl–Palladium Complexes towards Carbodiimides,Isothiocyanates, Nitriles,and Cyanamides

Complexes [Pd(C₆H₃XH‐2‐R′‐5)Y(N^N)] (X=O, NH; Y=Br, I; R′=H, NO₂; N^N=N,N,N′,N′‐tetramethylethylenediamine (tmeda), 2,2′‐bipyridine (bpy), 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy)) react with RN?C?E (E=NR, S) or RC≡N (R=alkyl, aryl, NR′′₂) and TlOTf (OTf=CF₃SO₃) to give, respectively, 1) products of the insertion of the C?E group into the C? Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{κ²‐X,E‐(XC₆H₃{EC(NHR)}‐2‐R′‐4)}(N^N)]OTf or [Pd(κ²‐X,N‐{ZC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{κ²‐C,N‐(C₆H₄{OC(NR)}NHR‐2)}(bpy)]OTf; or 2) products of the insertion of the C≡N group to Pd and N‐protonation, [Pd(κ²‐X,N‐{XC₆H₃(NH?CR)‐2‐R′‐4})(N^N)]OTf.     

Synthese und Struktur von [(Ph3PAu)6Co(CO)2](PF6) und [(Ph3PAu)7Co(CO)2](PF6)2

Synthesis and Structure of [(Ph₃PAu)₆Co(CO)₂](PF₆) and [(Ph₃PAu)₇Co(CO)₂](PF₆)₂ By the reaction of (Ph₃PAu)₄Co[(CO)₃]⁺ with OH^? in the presence of excess Ph₃PAuCl the larger cluster cations [(Ph₃PAu)₆Co(CO)₂]⁺ ( 1 ) and [(Ph₃PAu)₇Co(CO)₂]²⁺ ( 2 ) can be built up with 1 being the main product. 1 crystallizes with PF^?₆ as counterion in the monoclinic space group C2/c with a = 3008.3(6); b = 1339.1(2); c = 2909.4(6) pm; β = 103.08(1)°; Z = 4. The inner core of the cluster cation 1 with the symmetry C₂ has the form of a bicapped trigonal bipyramid with the heteroatom in equatorial position, and distances Au? Au between 280.4(1) and 288.4(1) pm and Co? Au between 254.9(1) and 257.1(2) pm. 2 · (PF₆)₂ crystallizes in the triclinic space group P1 with a = 2155.7(1); b = 1720.6(1); c = 3543.6(1) pm; α = 91.89(1)°; β = 97.51(1); γ = 89.92(1)°; Z = 4. The unit cell contains two symmetry independent cluster cations 2 of about the same geometry. The cluster skeleton Au₇Co can be described as fragment of an icosahedron formed by seven gold atoms with the Co atom in its center. The Au? Au distances range from 274.8(3) to 332.6(3) pm, and the Co? Au distances are 256.8(6) to 264.7(5) pm. The bonding in 1 and 2 is discussed.     

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands,meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

A series of tetragold(I) complexes supported by tetraphosphine ligands, meso‐ and rac‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso‐ and rac‐dpmppm) were synthesized and characterized to show that the tetranuclear Au^I alignment varies depending on syn‐ and anti‐arrangements of the two dpmppm ligands with respect to the metal chain. The structures of syn‐[Au₄(meso‐dpmppm)₂X]X′₃ (X=Cl; X′=Cl ( 4 a ), PF₆ ( 4 b ), BF₄ ( 4 c )) and syn‐[Au₄(meso‐dpmppm)₂]X₄ (X=PF₆ ( 4 d ), BF₄ ( 4 e ), TfO ( 4 f ); TfO=triflate) involved a bent tetragold(I) core with a counter anion X incorporated into the bent pocket. Complexes anti‐[Au₄(meso‐dpmppm)₂]X₄ (X=PF₆ ( 5 d ), BF₄ ( 5 e ), TfO ( 5 f )) contain a linearly ordered Au₄ string and complexes syn‐[Au₄(rac‐dpmppm)₂X₂]X′₂ (X=Cl, X′=Cl ( 6 a ), PF₆ ( 6 b ), BF₄ ( 6 c )) and syn‐[Au₄(rac‐dpmppm)₂]X₄ (X=PF₆ ( 6 d ), BF₄ ( 6 e ), TfO ( 6 f )) consist of a zigzag tetragold(I) chain supported by the two syn‐arranged rac‐dpmppm ligands. Complexes 4 d–f , 5 d–f , and 6 d–f with non‐coordinative large anions are strongly luminescent in the solid state (λ_max=475–515 nm, Φ=0.67–0.85) and in acetonitrile (λ_max=491–520 nm, Φ=0.33–0.97); the emission was assigned to phosphorescence from ³[d_σ*σ*σ*p_σσσ] excited state of the Au₄ centers on the basis of DFT calculations as well as the long lifetime (a few μs). The emission energy is predominantly determined by the HOMO and LUMO characters of the Au₄ centers, which depend on the bent ( 4 ), linear ( 5 ), and zigzag ( 6 ) alignments. The strong emissions in acetonitrile were quenched by chloride anions through simultaneous dynamic and static quenching processes, in which static binding of chloride ions to the Au₄ excited species should be the most effective. The present study demonstrates that the structures of linear tetranuclear gold(I) chains can be modified by utilizing the stereoisomeric tetraphosphines, meso‐ and rac‐dpmppm, which may lead to fine tuning of the strongly luminescent properties intrinsic to the Au^I₄ cluster centers.     

Cyclometalated Iridium(III) and Rhodium(III) Complexes Containing Naphthyridine Ligands: Synthesis,Characterization and Biological Studies

The synthesis, crystal structure, and biological activity of new bis‐cyclometalated compounds [M(ptpy)₂(4‐chloro‐2‐methyl‐1,8‐naphthyridine)]PF₆ [M = Rh ( 1 ); M = Ir ( 2 ); ptpy = 2‐(p‐tolyl)pyridinato] and [M(ptpy)₂(2‐methyl‐1,8‐naphthyridine)]PF₆ [M = Rh ( 3 ); M = Ir ( 4 )] are described. The new compounds were prepared by the reaction of [{M(μ‐Cl)(ptpy)₂}₂] (M = Rh, Ir) with the corresponding naphthyridine ligands. The molecular structures of compounds 1 , 3 , and 4 were confirmed by single‐crystal X‐ray diffraction studies.     

Syntheses,Spectroscopic, Electrochemical,and Third‐Order Nonlinear Optical Studies of a Hybrid Tris{ruthenium(alkynyl)/(2‐phenylpyridine)}iridium Complex

The synthesis of fac‐[Ir{N,C₁′‐(2,2′‐NC₅H₄C₆H₃‐5′‐C?C‐1‐C₆H₂‐3,5‐Et₂‐4‐C?CC₆H₄‐4‐C?CH)}₃] ( 10 ), which bears pendant ethynyl groups, and its reaction with [RuCl(dppe)₂]PF₆ to afford the heterobimetallic complex fac‐[Ir{N,C₁′‐(2,2′‐NC₅H₄C₆H₃‐5′‐C?C‐1‐C₆H₂‐3,5‐Et₂‐4‐C?CC₆H₄‐4‐C?C‐trans‐[RuCl(dppe)₂])}₃] ( 11 ) is described. Complex 10 is available from the two‐step formation of iodo‐functionalized fac‐tris[2‐(4‐iodophenyl)pyridine]iridium(III) ( 6 ), followed by ligand‐centered palladium‐catalyzed coupling and desilylation reactions. Structural studies of tetrakis[2‐(4‐iodophenyl)pyridine‐N,C₁′](μ‐dichloro)diiridium 5 , 6 , fac‐[Ir{N,C₁′‐(2,2′‐NC₅H₄C₆H₃‐5′‐C?C‐1‐C₆H₂‐3,5‐Et₂‐4‐C?CH)}₃] ( 8 ), and 10 confirm ligand‐centered derivatization of the tris(2‐phenylpyridine)iridium unit. Electrochemical studies reveal two ( 5 ) or one ( 6 – 10 ) Ir‐centered oxidations for which the potential is sensitive to functionalization at the phenylpyridine groups but relatively insensitive to more remote derivatization. Compound 11 undergoes sequential Ru‐centered and Ir‐centered oxidation, with the potential of the latter significantly more positive than that of Ir(N,C′‐NC₅H₄‐2‐C₆H₄‐2)₃. Ligand‐centered π–π* transitions characteristic of the Ir(N,C′‐NC₅H₄‐2‐C₆H₄‐2)₃ unit red‐shift and gain in intensity following the iodo and alkynyl incorporation. Spectroelectrochemical studies of 6 , 7 , 9 , and 11 reveal the appearance in each case of new low‐energy LMCT bands following formal Ir^III/IV oxidation preceded, in the case of 11 , by the appearance of a low‐energy LMCT band associated with the formal Ru^II/III oxidation process. Emission maxima of 6 – 10 reveal a red‐shift upon alkynyl group introduction and arylalkynyl π‐system lengthening; this process is quenched upon incorporation of the ligated ruthenium moiety on proceeding to 11 . Third‐order nonlinear optical studies of 11 were undertaken at the benchmark wavelengths of 800 nm (fs pulses) and 532 nm (ns pulses), the results from the former suggesting a dominant contribution from two‐photon absorption, and results from the latter being consistent with primarily excited‐state absorption.     

Über die Kristallstrukturen von CH3PF2H+AsF6− und CH3PF2H+SbF6− und eine einfache Darstellung von CH3PF2

On the Crystal Structures of CH₃PF₂H⁺AsF₆^? and CH₃PF₂H⁺SbF₆^? and a simple Method for Preparation of CH₃PF₂ A simple method for preparation of CH₃PF₂ from CH₃PCl₂ is reported. The phosphonium salts CH₃PF₂H⁺MF₆^? are obtained by the reaction of CH₃PCl₂ with superacidic systems HF/MF₅ (M = As, Sb). CH₃PF₂H⁺SbF₆^? crystallizes in the space group P1 with a = 548.4(4) pm, b = 695.5(8) pm, c = 960.2(9) pm, α = 94.68(5)°, β = 97.19(6)°, γ = 94.41(6)° and Z = 2. CH₃PF₂H⁺SbF₆^? crystallizes in P1 with a = 554.3(3), b = 724.2(4), c = 970.4(5), α = 94.73(4)°, β = 96.14(5)°, γ = 95.30(4)°.     

Cationic Iridium(III) Complex Containing both Triarylboron and Carbazole Moieties as a Ratiometric Fluoride Probe That Utilizes a Switchable Triplet–Singlet Emission

A novel cationic Ir^III complex [Ir(Bpq)₂(CzbpyCz)]PF₆ (Bpq=2‐[4‐(dimesitylboryl)phenyl]quinoline, CzbpyCz = 5,5′‐bis(9‐hexyl‐9H‐carbazol‐3‐yl)‐2,2′‐bipyridine) containing both triarylboron and carbazole moieties was synthesized. The excited‐state properties of [Ir(Bpq)₂(CzbpyCz)]PF₆ were investigated through UV/Vis absorption and photoluminescence spectroscopy and molecular‐orbital calculations. This complex displayed highly efficient orange‐red phosphorescent emission with an emission peak of 583 nm and quantum efficiency of Φ=0.30 in dichloromethane at room temperature. The binding of fluoride ions to [Ir(Bpq)₂(CzbpyCz)]PF₆ can quench the phosphorescent emission from the Ir^III complex and enhance the fluorescent emission from the N^N ligand, which corresponds to a visual change in the emission from orange‐red to blue. Thus, both colorimetric and ratiometric fluoride sensing can be realized. Interestingly, an unusual intense absorption band in the visible region was observed. And the detection of F^? ions can also be carried out with visible light as the excitation wavelength. More importantly, the linear response of the probe absorbance change at λ=351 nm versus the concentration of F^? ions allows efficient and accurate quantification of F^? ions in the range 0–50 μM .     

Decreased Turn‐On Times of Single‐Component Light‐Emitting Electrochemical Cells by Tethering an Ionic Iridium Complex with Imidazolium Moieties

We report a significant decrease in turn‐on times of light‐emitting electrochemical cells (LECs) by tethering imidazolium moieties onto a cationic Ir complex. The introduction of two imidazolium groups at the ends of the two alkyl side chains of [Ir(ppy)₂(dC6‐daf)]⁺(PF₆)^? (ppy=2‐phenylpyridine, dC6‐daf=9,9′‐dihexyl‐4,5‐diazafluorene) gave the complex [Ir(ppy)₂(dC6MIM‐daf)]³⁺[(PF₆)^?]₃ (dC6MIM‐daf=9,9‐bis[6‐(3‐methylimidazolium)hexyl]‐1‐yl‐4,5‐diazafluorene). Both complexes exhibited similar photoluminescent/electrochemical properties and comparable electroluminescent efficiencies. The turn‐on times of the LECs based on the latter complex, however, were much lower than those of devices based on the former. The improvement is ascribed to increased concentrations of mobile counterions ((PF₆)^?) in the neat films and a consequent increase in neat‐film ionic conductivity. These results demonstrate that the technique is useful for molecular modifications of ionic transition‐metal complexes (ITMCs) to improve the turn‐on times of LECs and to realize single‐component ITMC LECs compatible with simple driving schemes.     

Study of the Bonding Modes of Di‐2‐pyridyl ketoxime Ligand towards Ruthenium,Rhodium and Iridium Half Sandwich Complexes

The bonding modes of the ligand di‐2‐pyridyl ketoxime towards half‐sandwich arene ruthenium, Cp*Rh and Cp*Ir complexes were investigated. Di‐2‐pyridyl ketoxime {pyC(py)NOH} react with metal precursor [Cp*IrCl₂]₂ to give cationic oxime complexes of the general formula [Cp*Ir{pyC(py)NOH}Cl]PF₆ ( 1a ) and [Cp*Ir{pyC(py)NOH}Cl]PF₆ ( 1b ), for which two coordination isomers were observed by NMR spectroscopy. The molecular structures of the complexes revealed that in the major isomer the oxime nitrogen and one of the pyridine nitrogen atoms are coordinated to the central iridium atom forming a five membered metallocycle, whereas in the minor isomer both the pyridine nitrogen atoms are coordinated to the iridium atom forming a six membered metallacyclic ring. Di‐2‐pyridyl ketoxime react with [(arene)MCl₂]₂ to form complexes bearing formula [(p‐cymene)Ru{pyC(py)NOH}Cl]PF₆ ( 2 ); [(benzene)Ru{pyC(py)NOH}Cl]PF₆ ( 3 ), and [Cp*Rh{pyC(py)NOH}Cl]PF₆ ( 4 ). In case of complex 3 the ligand coordinates to the metal by using oxime nitrogen and one of the pyridine nitrogen atoms, whereas in complex 4 both the pyridine nitrogen atoms are coordinated to the metal ion. The complexes were fully characterized by spectroscopic techniques.     

Synthese,Struktur und Photochemie von Olefiniridium(I)‐Komplexen mit Acetylacetonatoliganden

Synthesis, Structure, and Photochemical Behavior of Olefine Iridium(I) Complexes with Acetylacetonato Ligands The bis(ethene) complex [Ir(κ²‐acac)(C₂H₄)₂] ( 1 ) reacts with tertiary phosphanes to give the monosubstitution products [Ir(κ²‐acac)(C₂H₄)(PR₃)] ( 2 – 5 ). While 2 (R = iPr) is inert toward PiPr₃, the reaction of 2 with diphenylacetylene affords the π‐alkyne complex [Ir(κ²‐acac)(C₂Ph₂)(PiPr₃)] ( 6 ). Treatment of [IrCl(C₂H₄)₄] with C‐functionalized acetylacetonates yields the compounds [Ir(κ²‐acacR^1,2)(C₂H₄)₂] ( 8 , 9 ), which react with PiPr₃ to give [Ir(κ²‐acacR^1,2)(C₂H₄)(PiPr₃)] ( 10 , 11 ) by displacement of one ethene ligand. UV irradiation of 5 (PR₃ = iPr₂PCH₂CO₂Me) and 11 (R² = (CH₂)₃CO₂Me) leads, after addition of PiPr₃, to the formation of the hydrido(vinyl)iridium(III) complexes 7 and 12 . The reaction of 2 with the ethene derivatives CH₂=CHR (R = CN, OC(O)Me, C(O)Me) affords the compounds [Ir(κ²‐acac)(CH₂=CHR)(PiPr₃)] ( 13 – 15 ), which on photolysis in the presence of PiPr₃ also undergo an intramolecular C–H activation. In contrast, the analogous complexes [Ir(κ²‐acac)(olefin)(PiPr₃)] (olefin = (E)‐C₂H₂(CO₂Me)₂ 16 , (Z)‐C₂H₂(CO₂Me)₂ 17 ) are photochemically inert.     

Synthesis and characterization of iridium polypyridyl complexes with ester groups with potential applications in covalent attachment to metal oxide surfaces

We report the synthesis and characterization of two iridium polypyridyl complexes, [Ir(deeb)₂Cl₂](PF₆) and [Ir(deeb)₂(dpp)](PF₆)₃, where deeb?=?diethyl-2,2′-bipyridine-4,4′-dicarboxylate and dpp?=?2,3-bis(2-pyridyl)pyrazine. From ¹H NMR spectral data, the two deeb ligands are attached to Ir cis to each other. Mass spectra contain fragmentation patterns of the (M-PF₆)⁺ and (M-3PF₆)³⁺ molecular ions for [Ir(deeb)₂Cl₂](PF₆) and [Ir(deeb)₂(dpp)](PF₆)₃, respectively. The electronic absorption spectrum of [Ir(deeb)₂Cl₂](PF₆) shows maxima at 308?nm and 402?nm, which are assigned as ¹π?→?π* and metal-to-ligand charge transfer transitions, respectively. [Ir(deeb)₂(dpp)](PF₆)₃ exhibits peaks due to ¹π?→?π* transitions at 322?nm and 334?nm. [Ir(deeb)₂Cl₂](PF₆) has emission peaks at 538?nm in acetonitrile and 567?nm in the solid state, with lifetimes of 1.71?µs and 0.35?µs, respectively. [Ir(deeb)₂Cl₂](PF₆) has an unusually higher quantum yield than analogous compounds. [Ir(deeb)₂(dpp)](PF₆)₃ has emission peaks at 540?nm in acetonitrile and 599?nm in the solid state with lifetimes of 1.23?µs and 0.14?µs, respectively. Cyclic voltammetry of [Ir(deeb)₂Cl₂](PF₆) yields two reversible couples at ?0.72 and ?0.87?V versus Ag/AgCl, both corresponding to deeb ligand reductions, and a quasi-reversible couple at ?1.48?V corresponding to Ir^3+/+ reduction. Electrochemical reduction of [Ir(deeb)₂(dpp)](PF₆)₃ yields couples at ?0.38, ?0.54, ?0.71, and ?1.33?V, assigned as deeb^0/?, deeb^0/?, dpp^0/?, and Ir^3+/+ reductions, respectively.     

Phosphaniminate von Alkalimetallen: Die Kristallstrukturen von [KNPCy3]4, [KNPCy3]4·2OPCy3, [CsNPCy3]4·4OPCy3 und [Li4(NPPh3)(OSiMe2NPPh3)3(DME)]

The alkalimetal phosphoraneiminates [KNPCy₃]₄, ( 1 ) [KNPCy₃]₄·2OPCy₃ ( 2 ) and [CsNPCy₃]₄·4OPCy₃ ( 3 ) (Cy = cyclohexyl) which are obtainable by the reaction of pottassium amide or cesium amide with Cy₃PI₂ or Cy₃PBr₂ in liquid ammonia, as well as the lithium derivative [Li₄(NPPh₃)(OSiMe₂NPPh₃)₃(DME)] ( 4 ) have been characterized by crystal structure determinations. 4 has been formed by the insertion reaction of silicon greaze (‐OSiMe₂)n into the LiN bonds of [LiNPPh₃]₆ in DME solution (DME = 1, 2‐dimethoxyethane). 1 : Space group P&1macr;, Z = 2, lattice dimensions at 193 K: a = 1389.8(1); b = 1408.1(1); c = 2205.2(2) pm; α = 78.952(10)?; β = 81.215(10)?; γ = 66.232(8)?; R1 = 0.0418. 2 : Space group Pbcn, Z = 4, lattice constants at 193 K: a = 2943.6(2); b = 2048.2(1); c = 1893.8(1) pm; R1 = 0.0428. 3 : Space group Cmc2₁, Z = 4, lattice dimensions at 193 K: a = 2881.6(2); b = 2990.2(2); c = 1883.7(2) pm; R1 = 0.0586. 4 ·1/2DME: Space group R&3macr;c, Z = 12, lattice dimensions at 193 K: a = b = 1583.5(1); c = 11755.3(5) pm; R1 = 0.0495. All complexes have heterocubane structures. In 1‐3 they are formed by four alkali metal atoms and by the nitrogen atoms of the (μ₃‐NPCy₃^‐) groups, whereas 4 forms a "heteroleptic" Li₄NO₃ heterocubane.     

M(H2O)2(4,4′‐bipy)[C6H4(COO)2]·2H2O (M = Mn2+, Co2+) – Zwei isotype Koordinationspolymere mit Schichtstruktur

M(H₂O)₂(4,4′‐bipy)[C₆H₄(COO)₂]·2H₂O (M = Mn²⁺, Co²⁺) – Two Isotypic Coordination Polymers with Layered Structure Monoclinic single crystals of Mn(H₂O)₂(4,4′‐bipy)[C₆H₄(COO)₂]·2H₂O ( 1 ) and Co(H₂O)₂(4,4′‐bipy)[C₆H₄(COO)₂]· 2H₂O ( 2 ) have been prepared in aqueous solution at 80 °C. Space group P2/n (no. 13), Z = 2; 1 : a = 769.20(10), b = 1158.80(10), c = 1075.00(10) pm, β = 92.67(2)°, V = 0.9572(2) nm³; 2 : a = 761.18(9), b = 1135.69(9), c = 1080.89(9) pm, β = 92.276(7)°, V = 0.9337(2) nm³. M²⁺ (M = Mn, Co), which is situated on a twofold crystallographic axis, is coordinated in a moderately distorted octahedral fashion by two water molecules, two oxygen atoms of the phthalate anions and two nitrogen atoms of 4,4′‐biypyridine ( 1 : M–O 219.5(2), 220.1(2) pm, M–N 225.3(2), 227.2(2) pm; 2 : Co–O 212.7(2), 213.7(2) pm, Co–N 213.5(3), 214.9(3) pm). M²⁺ and [C₆H₄(COO)₂)]^2? build up chains, which are linked by 4,4′‐biyridine molecules to yield a two‐dimensional coordination polymer with layers parallel to (001).Thermogravimetric analysis in air of 1 indicated a loss of water of crystallization between 154 and 212 °C and in 2 between 169 and 222 °C.     

Charge Effects in PCP Pincer Complexes of NiII bearing Phosphinite and Imidazol(i)ophosphine Coordinating Jaws: From Synthesis to Catalysis through Bonding Analysis

This contribution reports on a new family of Ni^II pincer complexes featuring phosphinite and functional imidazolyl arms. The proligands ^RPIMC^HOP^R′ react at room temperature with Ni^II precursors to give the corresponding complexes [(^RPIMCOP^R′)NiBr], where ^RPIMCOP^R=κ^P,κ^C,κ^P‐{2‐(R′₂PO),6‐(R₂PC₃H₂N₂)C₆H₃}, R=iPr, R′=iPr ( 3 b , 84 %) or Ph ( 3 c , 45 %). Selective N‐methylation of the imidazole imine moiety in 3 b by MeOTf (OTf=OSO₂CF₃) gave the corresponding imidazoliophosphine [(^iPrPIMIOCOP^iPr)NiBr][OTf], 4 b , in 89 % yield (^iPrPIMIOCOP^iPr=κ^P,κ^C,κ^P‐{2‐(iPr₂PO),6‐(iPr₂PC₄H₅N₂)C₆H₃}). Treating 4 b with NaOEt led to the NHC derivative [(NHCCOP^iPr)NiBr], 5 b , in 47 % yield (NHCCOP^iPr=κ^P,κ^C,κ^C‐{2‐(iPr₂PO),6‐(C₄H₅N₂)C₆H₃)}). The bromo derivatives 3–5 were then treated with AgOTf in acetonitrile to give the corresponding cationic species [(^RPIMCOP^R)Ni(MeCN)][OTf] [R=Ph, 6 a (89 %) or iPr, 6 b (90 %)], [(^RPIMIOCOP^R)Ni(MeCN)][OTf]₂ [R=Ph, 7 a (79 %) or iPr, 7 b (88 %)], and [(NHCCOP^R)Ni(MeCN)][OTf] [R=Ph, 8 a (85 %) or iPr, 8 b (84 %)]. All new complexes have been characterized by NMR and IR spectroscopy, whereas 3 b , 3 c , 5 b , 6 b , and 8 a were also subjected to X‐ray diffraction studies. The acetonitrile adducts 6 – 8 were further studied by using various theoretical analysis tools. In the presence of excess nitrile and amine, the cationic acetonitrile adducts 6 – 8 catalyze hydroamination of nitriles to give unsymmetrical amidines with catalytic turnover numbers of up to 95.