Five- and six-membered platinacycles derived from phenantryl and anthracenyl imines

The reaction of [Pt₂Me₄(μ-SMe₂)₂] with ligands Me₂NCH₂CH₂NCHAr (2a, Ar=9-phenantryl; 2b, Ar=9-anthracenyl) carried out in acetone at room temperature produced the corresponding compounds [PtMe₂{9-(Me₂NCH₂CH₂NCH)C₁₄H₉}] (3) in which the imines act as bidentate [N,N^′] ligands. Refluxing toluene solutions of compounds 3 gave cyclometallated [C,N,N^′] compounds [PtMe{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (4) as a mixture of two isomers containing either a five- or a six-membered metallacycles for 3a and as a single isomer containing a six-membered metallacycle for 3b. The reactions of compounds 4 with acetyl chloride and with methyl iodide produced, respectively, compounds [PtCl{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (5) and [PtMe₂I{9-(Me₂NCH₂CH₂NCH)C₁₄H₈}] (6). All compounds were characterised by NMR spectroscopies and analytical data.     

Reactivity of titanium imidazolin-2-iminato complexes with 2,6-diisopropylaniline and 2-{(2,6-diisopropylphenyl)-iminomethyl}pyrrole

Abstract

We report the reactions of imidazolin-2-iminato titanium complexes [(Im^RN)Ti(NMe₂)₃] (R = Mes, 2b; R = Dipp, 2c; Mes = mesityl, Dipp = 2,6-diisopropylphenyl) with 2,6-diisopropylaniline in a 1:3 molar ratio to yield the titanium imido complexes of composition [(Im^RNH)Ti = N(^Dipp)(HN^Dipp)₂] (R = Mes, 3b; R = Dipp, 3c) in good yield by the Ti-Niminato bond cleavage at 60 °C. In contrast, the reaction of [(Im^RN)Ti(NMe₂)₃] with 2,6-diisopropylaniline in a 1:1 molar ratio afforded mono-substituted products [(Im^RN)Ti(NMe₂)₂(HN^Dipp)] (R = Mes, 4b; R = Dipp, 4c) in good yield. The reaction of [(Im^RN)Ti(NMe₂)₃] with the iminopyrrole ligand [2-(2,6-iPr₂C₆H₃-N = CH)C₄H₃NH] (N^DippPyH) in a 1:1 ratio afforded mixed ligands, titanium complexes [(Im^RN)Ti(NMe₂)₂(N^Dipp-Py)] (R = tBu, 5a; R = Dipp, 5c) with imidazolin-2-iminato and iminopyrrolide ligands. Molecular structures of 3b, 3c, 4c, 5a, and 5c were determined by single-crystal X-ray analysis. The solid-state structures of 3b and 3c clearly indicate the formation of true Ti = N double bonds, measuring 1.730(2) Å and 1.727(1) Å, respectively. The solid-state structures of 5a and 5c reveal the formation of five-coordinate titanium complexes.     

Coordination Chemistry of Tetrakis(diphenylphosphinomethyl)methane: Binuclear,Tetranuclear and Polymeric Complexes

The ligand tetrakis(diphenylphosphinomethyl)methane, tpmm, binds in a η², η²- bridging mode to square planar platinum(II) or palladium(II) centers to give complexes such as [Pt₂Me₄(μ-tpmm)] or [Pd₂Cl₄(μ-tpmm)]. These complexes yielded triflate derivatives [Pt₂Me₂(OTf)₂(μ-tpmm)] or [Pd₂(OTf)₄(μ-tpmm)], and displacement of triflate by a bipyridine ligand then gave the cationic polymers [{Pt₂Me₂(μ-LL)(μ-tpmm)}_n]²ⁿ⁺ or the cationic network materials [{Pd₂(μ-LL)₂(μ-tpmm)}_n]⁴ⁿ⁺, LL=4,4’-bipyridine or 1,3-C₆H₄(CONH-4-C₅H₄N)₂. Ligand tpmm reacts with copper(I) iodide to give [Cu₄I₄(μ-tpmm)₂] or with silver(I) triflate to give [Ag₂(OTf)₂(μ-tpmm)], which then reacts with LL=1,3-C₆H₄(CONH-4-C₅H₄N)₂ to give the polymeric complex [{Ag₂(μ-LL)(μ-tpmm)}_n]²ⁿ⁺. The structure determination of [Cu₄I₄(μ-tpmm)₂] shows that it contains two isomeric forms with the tpmm ligands in either the η², η²- or η³, η¹- bridging mode.     

The synthesis of platinum and palladium cluster compounds with isocyanide or functionalised phosphine ligands. Crystal structures of [Pt5(CO)(μ-CO)5{Ph2PCH2C(O) Ph}4 and [Pt5(μ-CNC6H3Me2-2, 6)3(CNC6H3Me2-2, 6)5 {Ph2PCH2C(O) Ph}2]

The reaction of the ketophosphine ligand Ph₂PCH₂C(O)Ph (P～O) with [PtCl₂(NCMe)₂] and carbon monoxide in THF in the presence of an excess of zinc afforded the 70 electron pentanuclear cluster [Pt₅(CO)(μ-CO)₅(P～O)₄] (1). Reaction of the palladium(0) complex [Pd₂(dba)₃] CHCl₃ (dba = dibenzylideneacetone) with Ph₂PCH₂C(O)R [R = Ph or C₅H₄Fe(C₅H₅)] under SO₂ led to the pentapalladium cluster compounds [Pd₅(μ₃-SO₂)₂ (μ-SO₂)₂ {Ph₂PCH₂C(O)R}₅] (2a,R = Ph;2b,R = C₅H₄Fe(C₅H₅)), Cluster (1) reacts with 2,6-xylyl isocyanide, CNC₆H₃Me₂-2,6 to give a red cluster of formula [Pt₅(μ-CNC₆H₃Me₂-2, 6)₃ (CNC₆H₃Me₂-2, 6)₅ (P～O)₂] (3) and a green complex (4). The corresponding complexes (6) and (7) were also obtained by using PPh₃ instead of P～O. Clusters (2a) and (2b) react with [NEt₃Bz] Cl to give[NEt₃Bz][Pd₃(μ-SO₂)₂ (μ-Cl){Ph₂PCH₂C(O)R}₃](8a,R = Ph;8b,R = C₅H₄Fe(C₅H₅)). The molecular structures of (1) and (3) were determined by single-crystal X-ray diffraction analyses.     

Palladium(II) complexes of Y,C,Y‐chelated phosphines: synthesis,structure, and catalytic activity in Suzuki–Miyaura reaction

The phosphines L¹PPh₂ (1) and L²PPh₂ (2) containing different Y,C,Y‐chelating ligands, L¹ = 2,6‐(^tBuOCH₂)₂C₆H₃^? and L² = 2,6‐(Me₂NCH₂)₂C₆H₃^?, were treated with PdCl₂ and di‐µ‐chloro‐bis[2‐[(N,N‐dimethylamino)methyl]phenyl‐C,N]‐dipalladium(II) and yielded complexes trans‐{[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}₂PdCl₂ (3), {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂} PdCl₂ (4), {[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}Pd(Cl)[2‐(Me₂NCH₂)C₆H₄] (5) and {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}Pd(Cl)[2‐(Me₂NCH₂)C₆H₄] (6) as the result of different ability of starting phosphines 1 and 2 to complex PdCl₂. Compounds 3–6 were characterized by ¹H, ¹³C, ³¹P NMR spectroscopy and ESI‐MS. The molecular structures of 3,4 and 6 were also determined by X‐ray diffraction analysis. The catalytic activity of complexes 3–6 was evaluated in the Suzuki‐Miyaura cross‐coupling reaction. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of secondary ligand on structures and topologies of lanthanide coordination polymers with 1,3,5-triazine-2,4,6-triamine hexaacetic acid

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln₄(TTHA)₂(pzac)(H₃O)₂(H₂O)]·5H₂O (Ln = Pr (1a) and Nd (1b)), [Sm₈(TTHA)₄(pzac)_0.5(H₃O)(H₂O)_7.5]·4H₂O (2), [Ln₄(HTTHA)₂(SO₄)(H₂O)₄]·5H₂O (Ln = Pr (3a) and Nd (3b)), where H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H₂pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H₆TTHA as the primary ligand and either the in situ generated pzac^2? or sulfate as the secondary ligands. The influence of the deprotonated H₆TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.     

Reactions of [Pd(C6F5)2(CNR)2] with [PdCl2(NCPh)2]. Insertion of p-MeC6H4NC into Pd-C6F5 bonds

[Pd(C₆F₅)₂(CNR)₂] (R = Cy, Bu^t, p-MeC₆H₄ (p-Tol)) react with [PdCl₂(NCPh)₂] to give [Pd₂(μ-Cl)₂(C₆F₅)₂(CNR)₂]. In refluxing benzene insertion of isocyanide into the C₆F₅Pd bonds occurs only for R = p-Tol, to give a imidoyl bridged polynuclear complex cis-[Pd₂ (μ-Cl)₂[μ-C(C₆F₅) = N(Tol-p)]_2n]. This complex reacts with (a) Tl(acac) to give [Pd₂{μ-C(C₆F₅) = N(Tol-p)}₂(acac)₂]; (b) neutral monodentate ligands to afford dimeric complexes [Pd₂{μ-C(C₆F₅) = N(Tol-p)}₂Cl₂L₂] (L = NMe₃, py, 4-Me-py, SC₄H₈), and (c) isocyanides to give insoluble complexes of the same composition which are thought to be polymeric, [$\text{Pd}$(CNR)Cl{μ-C(C₆F₅) = $\text{N}$(p-Tol)}]_n (R = p-Tol, Me, Bu^t). Thermal decomposition of cis-[Pd₂ (μ-Cl)₂ [μ-C(C₆F₅) = N( p-Tol)]_2n] gives the diazabutadiene species (p-Tol)NC(C₆F₅)C(C₆F₅)N(p-Tol) in high yield.     

Crystal and Molecular Structure of [2,6‐(Me2NCH2)2C6H3]2SnF2, an Intramolecularly Coordinated Diorganotin Difluoride

Single‐crystal X‐ray diffraction analysis of [2,6‐(Me₂NCH₂)₂C₆H₃]₂SnF₂ reveals that only one of the two dimethylaminomethyl groups of each pincer‐type ligands [2,6‐(CH₂NMe₂)₂C₆H₃]^? is coordinated to the tin atom at Sn‐N distances of 2.576(2) and 2.470(2) Å, inducing chirality of the latter. The tin atom exhibits a distorted octahedral trans(C,C)cis(N,N)cis(F,F) configuration. Extensive intra‐ and intermolecular C‐H···F hydrogen bonding is observed with the latter giving rise to formation of polymeric chains.     

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

The reaction of 2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃I (2) with Pd₂(dba)₃ produced the NCN diamine pincer complex [2,6-(2-Me₂{NCH₂}C₆H₄)₂C₆H₃PdI] (3) by an oxidative addition route. The structural analysis of ligand precursor 2 revealed a syn-conformation in the solid state. Single crystal X-ray analysis of complex 3 revealed a conventional square planar geometry about the palladium center and a global C₂ symmetric structure. Variable temperature and concentration NMR spectroscopic studies of complex 3 suggest an equilibrium between 3 and the dinuclear species [{2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃Pd}₂μ²-I]I in CDCl₃ solution. An unusual carbonate complex [{2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃Pd}₃μ³-CO₃]I₃ (4) was also structurally characterized as a minor product during synthesis of 3.     

Ouebergangsmetall-substituierte phosphane,arsane und stibane: LI. Bis-metallate Na2{Me2Si[(C5H4)(CO)3M]2} (M = Mo,W): darstellung und umwandlung in neutralkomplexe Me2Si[(C5H4)(CO)3MR]2 (R = Me,AsMe2) mit σ-gebundener dimethylarsenido- oder methylgruppe

The bis(sodium-metallates) Na₂{Me₂Si[(C₅H₄)M(CO)₃]₂} (4a: M = Mo, 4b, M = W), in which the metal centres are linked by their cyclopentadienyl ligands through a Me₂Si unit are obtained by the reaction of Na₂[(C₅H₄)₂SiMe₂] (2) with two moles M(CO)₆ (3a: M = Mo; 3b: M = W). Treatment of 4a with Me₂AsCl leads to the formation of the bis(metalloarsane) Me₂Si[(C₅H₄(CO)₃^- MoAsMe₂]₂ (5), which is quarternized by MeI at the arsenic atoms to give the dicationic complex {Me₂Si[(C₅H₄)(CO)₃MoAsMe₃]₂}I₂ (7). In reactions with the ylide Me₃PCH₂ cleavage of the MoAs bonds occurs, followed by transylidation to yield the bis(phosphonium metallate) [Me₄P]₂ {Me₂Si[(C₅H₄)Mo- (CO)₃]₂} (10) and Me₃PCHAsMe₂ (9). From 4a, 4b and MeI the dinuclear methyl complexes Me₂Si[(C₅H₄)(CO)₃MMe]₂ (6a: M=Mo; 6b: M=W) are obtained.     

Chemistry of N,N-Dimethylaminoalkylchalcogenolate Complexes of Palladium(II) and Platinum(II)

Abstract

Four different series of N,N-dimethylaminoalkylchalcogenolates, viz. Me₂NCH₂ CH₂E^?, Me₂NCH(Me)CH₂E^?, Me₂NCH₂CH(Me)E^?, and Me₂NCH₂CH₂CH₂E^? (E = S, Se, Te), (referred as E^∩N) have been synthesized and characterized. Their reactions with palladium(II) and platinum(II) precursors have been explored. Complexes of the general formula, [MCl(E^∩N)]_n, [MCl(E^∩N)₂]_n, [MCl(E^∩N)(PR₃)], [M₂Cl₂(μ-E^∩N)₂(PR₃)₂], [M₂(μ-E^∩N)₂(P^∩P)₂]²⁺, etc. have been isolated. All the complexes have been characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te, ¹⁹⁵Pt), UV-vis, and FAB mass spectral data. A weak absorption in the electronic spectra of [MCl(E^∩N)(PR₃)] has been attributed to metal mediated ligand-to-ligand charge transfer and showed pronounced chalcogen dependence being red shifted on moving from S → Se → Te. Structures of several complexes have been established by X-ray diffraction analyses. Thermal behavior of some of these complexes has been investigated by TGA.     

Computational Study of Bridge Splitting,Aryl Halide Oxidative Addition to PtII,and Reductive Elimination from PtIV: Route to Pincer-PtII Reagents with Chemical and Biological Applications

Density functional theory computation indicates that bridge splitting of [Pt^IIR₂(μ-SEt₂)]₂ proceeds by partial dissociation to form R₂Pt^a(μ-SEt₂)Pt^bR₂(SEt₂), followed by coordination of N-donor bromoarenes (L-Br) at Pt^a leading to release of Pt^bR₂(SEt₂), which reacts with a second molecule of L-Br, providing two molecules of PtR₂(SEt₂)(L-Br-N). For R=4-tolyl (Tol), L-Br=2,6-(pzCH₂)₂C₆H₃Br (pz=pyrazol-1-yl) and 2,6-(Me₂NCH₂)₂C₆H₃Br, subsequent oxidative addition assisted by intramolecular N-donor coordination via Pt^IITol₂(L-N,Br) and reductive elimination from Pt^IV intermediates gives mer-Pt^II(L-N,C,N)Br and Tol₂. The strong σ-donor influence of Tol groups results in subtle differences in oxidative addition mechanisms when compared with related aryl halide oxidative addition to palladium(II) centres. For R=Me and L-Br=2,6-(pzCH₂)₂C₆H₃Br, a stable Pt^IV product, fac-Pt^IVMe₂{2,6-(pzCH₂)₂C₆H₃-N,C,N)Br is predicted, as reported experimentally, acting as a model for undetected and unstable Pt^IVTol₂{L-N,C,N}Br undergoing facile Tol₂ reductive elimination. The mechanisms reported herein enable the synthesis of Pt^II pincer reagents with applications in materials and bio-organometallic chemistry.     

Unexpected results of the reactions of manganese and vanadium β-diketiminate halide complexes with Na[HBEt3]

The reaction of [(^Menacnac^Dipp)Mn(μ-Cl)]₂(2) (^Menacnac^Dipp = HC(C(Me)NDipp)₂; Dipp = 2,6-Prⁱ₂C₆H₃) with sodium triethylborohydride in a toluene—THF mixture afforded the complex [(^Menacnac^Dipp)Mn(μ-H)₂BEt₂(THF)] (3). The reaction of 2 with Na[HBEt₃] in toluene under THF-free conditions gave a mixture of products. The set and the ratio of these products in the resulting crystalline mixture were established by quantitative powder X-ray diffraction analysis: [(^Menacnac^Dipp)Mn(μ-H)]₂(1), [(^Menacnac^Dipp)?Mn(μ-H)₂BEt₂] (4), and unreacted compound 2 in the ratio of 15:4:1 and traces of an unknown crystalline phase. The reaction of [(^Menacnac^Dipp)VCl₂] (5) with Na[HBEt₃] yielded the compound [(^Menacnac^Dipp)V(μ-H)(μ,κ^1:1?C:C′?C₂H₄)BEt₂] (6) containing the unusual ligand [HBEt₂(CH₂CH₂)]^2?. The vanadium analog of compound 3, [(^Menacnac^Dipp)V(μ-H)₂BEt₂(THF)] (7), was isolated in one experiment. Besides. a small amount of the complex [(^Menacnac^Dipp)V(μ-H)BEt₃(THF)] (8) was detected in the mixture of crystalline products. The structures of compounds 3, 4, 6, 7, and 8 were determined by single-crystal X-ray diffraction.

     

Synthesis and cytostatic activity of Pt(II) complexes of intramolecularly coordinated phosphine and stibine ligands

The intramolecularly coordinated phosphine and stibine ligands L¹PPh₂ ( 1 ), L²PPh₂ ( 2 ) and L²SbPh₂ ( 3 ) containing Y,C,Y‐chelating ligands, L¹ = 2,6‐(^tBuOCH₂)₂C₆H₄^? and L² = 2,6‐(Me₂NCH₂)₂C₆H₄^?, were prepared and characterized. The treatment of these ligands 1 , 2 , 3 with PtCl₂ yielded complexes trans‐{[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}₂PtCl₂ (4), cis‐{[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}PtCl₂ (5), and cis‐{[2,6‐(Me₂NCH₂)₂C₆H₃]SbPh₂}PtCl₂ (6) as the result of different ability of the starting compounds 1 , 2 , 3 to complex platinum centre. Compounds 1 , 2 , 3 , 4 , 5 , 6 were characterized by ¹H, ¹³C and ³¹P NMR spectroscopy and electrospray ionization mass spectrometry, and molecular structures of 3 , 4 , 5 , 6 were determined by X‐ray diffraction analysis. The substitution reactions of complexes 4 , 5 , 6 were also studied. The reaction of 5 and 6 with NaI yielded complexes {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}PtI₂ ( 7 ) and {[2,6‐(Me₂NCH₂)₂C₆H₃]SbPh₂}PtI₂ ( 8 ), while the same reaction of 4 with NaI did not proceed. As the compounds 7 and 8 structurally resemble cisplatin, complex {{[2‐(Me₂NCH₂)‐6‐(Me₂NHCH₂)C₆H₃]PPh₂}PtCl₂}⁺Cl^? ( 9 ) was prepared as water‐soluble platinum complex. The cytotoxic effect of complex 9 was evaluated on human T‐lymphocytic leukemia cells MOLT‐4 (IC₅₀ = 27.6 ± 1.8 µmol l^?1) and human promyelocytic leukemia HL‐60 (IC₅₀ = 55.9 ± 4.9 µmol l^?1). Copyright © 2012 John Wiley & Sons, Ltd.     

Syntheses and Reactions of Dimolybdenum Alkyne Compounds Containing Functionally Substituted Ligands. The Crystal Structure of [Co2Mo2(μ4-CHCH)(μ-CO)4(CO)4-(η5-C5H4C(O)Me)2]

Abstract

Three dimolybdenum alkyne complexes containing functionally substituted ligands [Mo₂(μ-CHCH)(CO)₄(η⁵?C₅H₄C(O)R)₂] [R ? OEt, (1a); R ? Me, (1b); R ? Ph, (1c)] were synthesized by reactions of acetylene with in situ generated metal-metal triply bonded complexes [Mo(CO)₂(η⁵?C₅H₄C(O)R)]₂ (R ? OEt, Me, Ph). Further reaction of (1a), (1b) or (1c) with Co₂(CO)₈ in refluxing toluene gave another three new butterfly compounds [Co₂Mo₂-(μ₄-CHCH)(μ-CO)₄(CO)₄(η⁵-C₅H₄C(O)R)₂] [R ? OEt, (2a); R ? Me, (2b); R ? Ph, (2c)]. The resulting compounds were characterized by elemental analyses, IR, ¹H NMR and MS. The crystal structure of (2b) was determined by single-crystal X-ray analysis. The results indicate that the existence of functional groups on the cyclopentadienyl ring has an influence on the reactivity of this type of complex.     

Hypercoordinated diorganoantimony(III) compounds of types [2-(Me2NCH2)C6H4]2SbL and [PhCH2N(CH2C6H4)2]SbL (L = Cl,ONO2, OSO2CF3). Synthesis,structure and catalytic behaviour in the Henry reaction

The compounds [2-(Me₂NCH₂)C₆H₄]₂SbL (L = ONO₂ ( 2 ), OSO₂CF₃ ( 3 )) and [PhCH₂N(CH₂C₆H₄)₂]SbL (L = ONO₂ ( 5 ), OSO₂CF₃ ( 6 )) were prepared by reacting [2-(Me₂NCH₂)C₆H₄]₂SbCl ( 1 ) and [PhCH₂N(CH₂C₆H₄)₂]SbCl ( 4 ), respectively, with the appropriate silver(I) salt in a 1:1 molar ratio. The new species 2 – 6 were structurally characterized in solution using multinuclear NMR and in the solid state using infrared spectroscopy. The solid-state structures for compounds 2 , 4 and 6, as well as for the hydrolysis ionic product [{2-(Me₂N⁺HCH₂)C₆H₄}{2-(Me₂NCH₂)C₆H₄}SbOH][CF₃SO₃]⁻ ( 3h ) were determined using single-crystal X-ray diffraction. Medium to strong intramolecular N→ Sb interactions were observed in all these four compounds, thus resulting in hypercoordinated organoantimony(III) species 14-Sb-6 in 2 and 10-Sb-4 in the cation of 3h and in 4 and 6 . Compounds 1 – 6 and the starting amines PhCH₂NMe₂ and PhCH₂N(CH₂C₆H₄Br-2)₂ were investigated as catalysts in the Henry (nitroaldol) addition of nitromethane to benzaldehyde. The activity of compounds 1 – 6 resulted as an effect of the cooperation of the positively charged antimony with the negatively charged nitrogen.     

Synthesis of new functionalized 5,5-dimethyl-1-pyrroline 1-oxides and their investigation as spin traps

The reactions of 5,5-dimethyl-3-oxo-1-pyrroline 1-oxide (3-oxo-DMPO, 1) with NH₂OH and N₂H₄ afforded oxime (2a) and hydrazone (2b), respectively. The reaction products were studied as spin traps for the short-lived radicals HO^·, Ph^·, PhCO₂ ^·, NC(Me₂)C^·, and NC(Me₂)CO^·. The nitroxides generated in the reactions of the above-mentioned short-lived radicals with nitrones 1 and 2a,b were characterized by ESR spectroscopy. Of these nitrones, oxime 2a is the most effective radical trap.     

Synthesis and structural characterization of mono- and dinuclear NiII and PdII complexes derived from tetradentate 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene

The reaction of Schiff base 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene (L) with either NiCl₂·6H₂O or [Pd^IICl₂(CH₃CN)₂]/Na[BF₄] in 1?:?1 stoichiometry yielded mononuclear ionic complexes, trans-[Ni^II(L)(H₂O)₂]Cl₂·3H₂O (1·3H₂O) and [Pd^II(L)][BF₄]₂ (2), respectively; the reaction of L with [Pd^IICl₂(CH₃CN)₂] in 1?:?2 ratio yielded dinuclear cis-[Pd^II ₂(μ-L)Cl₄] (3). Complexes 1–3 were characterized by vibrational spectroscopy and X-ray diffraction; diamagnetic 2 and 3 were also characterized by NMR in solution. The molecular structures of 1 and 2 displayed tetradentate coordination of L with formation of two five-membered and one six-membered chelate rings for both complexes. In 3, L showed bidentate coordination mode for each pyridylimine toward Pd^II. Complex 1 has distorted octahedral geometry around Ni^II and an extended hydrogen-bond network; distorted square planar geometry around Pd^II in 2 and 3 was observed.     

Ringsubstituierte [1]titanocenophane

The ring-substituted bis(cyclopentadienyl)silanesMe ₂Si(C₅H₅) (MeC₅H₄) (1a) andMe ₂Si(MeC₅H₄)₂ (2a) could be prepared by the reactions ofMe ₂SiCl₂ with C₅H₅Na andMeC₅H₄Na or only withMeC₅H₄Na, respectively. Metallation of1 a or2 a withn-BuLi and following reaction with TiCl₄ led to the first ringsubstituted [1]titanocenophanes,Me ₂Si(C₅H₄) (MeC₅H₃)TiCl₂ (1 b) orMe ₂Si(MeC₅H₃)₂ TiCl₂ (2 b), respectively. On reaction with NaI,1 b yieldedMe ₂Si(C₅H₄) (MeC₅H₃)TiI₂ (1 c). Structural assignments of the compounds could be made on the basis of their¹H NMR spectra.

     

基于一个四羧酸配体构筑的具有(4,8)-连接的镧系金属-有机框架材料及对小分子的检测试验

以3,3'',5,5''-四-（羧基苯基）联苯为配体（H₄L）,与镧系金属Ln（Ⅲ）盐反应,自组装形成了5个具有三维孔洞结构的镧系金属-有机框架材料：{[Ln₃L₂(H₂O)₇]·(OH)·10DMA}_n(Ln=Gd (1a); Ln=Ho(2a), {[Ln₃L₂(H₂O)₃]·(OH)·mDMA}_n (Ln=Er,m=10(1b); Ln=Yb, m=9(2b); Ln=Lu, m=10(3b))。单晶X射线衍射分析表明,这些MOFs属于2种系列的类质同晶化合物,分别属于正交晶系Ccca空间群和单斜晶系C2/c空间群。有机小分子溶剂交换荧光研究发现,2b对小分子二氯甲烷和甲苯荧光有增强效应,表现出良好的荧光探测功能。