Ruthenium-Catalyzed Cross-Metathesis of Trisubstituted Vinylsilanes with Light Alkenes

In the cross-metathesis reaction of tri(methyl, ethoxy)vinylsilanes with propene and/or 1-butene catalyzed by RuCl₂(PPh₃)₃ activated in benzene at 115–130 °C, a series of l-alkenylsilanes of general formula CH₃(CH₂)_mCH = CHSiMe_3−n(OEt)_n, where m=0, 1, and n=0–3 (1-silyl-1-alkenes), as well as of formula CH₂=C(Me)SiMe_3−n(OEt)_n, where n=1, 2 (2-silyl-1-alkenes), were obtained. Additional products determined were allysilanes of general formula CH₂=CHCH₂SiMe_3−n(OEt)_n and CH₃CH= CHCH₂SiMe_3−n(OEt)_n, where n=1–3. © 1997 John Wiley & Sons, Ltd.     

Synthesis,characterization and acceptor behavior of n-butyltin(IV)-2,4-dimethylphenoxides

The n-butyltin(IV) complexes, n-BuSnCl_3?x(OC₆H₃(CH₃)₂-2,4) _x (where x?=?1–3), have been synthesized in quantitative yields by employing the reaction of n-BuSnCl₃ with 2,4-dimethylphenol and sodium acetate in methanol and benzene solvents at room temperature. The complexes have been characterized by elemental analysis, molar conductivity, and FT-IR, ¹H- and ¹³C-NMR, and mass spectral studies. Thermal behavior has been studied by TG–DTA techniques. Lewis acid character of n-BuSn(OC₆H₃(CH₃)₂-2,4)₃ has been investigated by reacting it with bases such as 2,2′-bipyridine and 1,10-phenanthroline (B), Ph₃PO and Ph₃AsO (LO) and phosphorus and arsenic donors Ph₃P, Ph₃As, and As(SPh)₃ (L). The formation of 1?:?1 and 1?:?2 (metal?:?base) coordination compounds [n-BuSn(OC₆H₃(CH₃)₂-2,4)₃·B] and n-[BuSn(OC₆H₃(CH₃)₂-2,4)₃·2LO/2L] has been authenticated by physicochemical and IR spectral studies. In order to infer the biological relevance of newly synthesized complexes, the antibacterial activity has been assayed against six bacterial strains Klebsiella pneumoniae, Staphylococcus epidermidis, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi, and Escherichia coli. In this study, n-BuSnCl₂(OC₆H₃(CH₃)₂-2,4) and n-BuSnCl(OC₆H₃(CH₃)₂-2,4)₂ showed better activity than precursor and ligand, while n-BuSn(OC₆H₃(CH₃)₂-2,4)₃ did not exhibit improved activity.     

Co-hydrolysis products of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions: Part 2 [1]

²⁹Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O^–)_4/2 and CH₃Si(O^–)_3/2 units, (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that ²⁹Si NMR peaks due to Si(OSi)₃(O^–) units shift to lower frequencies by replacement of the adjacent Si(O^–)_4/2 units by CH₃Si(O^–)_3/2 units, in other words, with increasing m value in Si[OSi(O^–)₃]_{3 – m} [OSi(CH₃) (O^–)₂] _m (O^–) (m=0–2). Peaks from CH₃ Si(OSi)₃ units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH₃Si(O^–)_3/2 units in the cubic octameric siloxane framework of (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=2, 3), for both of which three isomers are present, have been estimated.     

Two- and three-dimensional coordination complexes constructed by 2-(1H-imidazol-1-methyl)-1H-benzimidazole: syntheses,structures, and fluorescent properties

Two new complexes, {[Zn(imb)(SO₄)]·H₂O}_n (1) and {[Cd₂(imb)₂(SO₄)₂(H₂O)]·CH₃OH}_n (2) (imb?=?2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been solvothermally synthesized. Single-crystal X-ray diffraction shows that 1 displays a 2-D (4,4) network, which is further extended to a 3-D supramolecular structure by hydrogen bonding interactions. Complex 2 exhibits a 3-D framework with (3,5)-connected (4²·6)₂(4²·6⁵·8³)₂ topology. The results indicate that changing metal ions can influence the coordination modes of sulfate, and then affect the structures of the complexes. In addition, IR and UV–vis spectra, powder X-ray diffraction patterns, thermogravimetric analyses, and fluorescent properties of both complexes have been investigated.     

Assembly and Dissociation of Α-Cyclodextrin [2]Pseudorotaxanes with α,ω-Bis(N-(N,N′-dimethylethylenediamine)alkane Threads

A series of novel bischelate bridging ligands, CH₃NH(CH₂)₂N(CH₃)(CH₂)_nN(CH₃)(CH₂)₂NHCH₃ (n = 9, 10, 11, and 12) were synthesized as hydrochloride salts and characterized by elemental analyses, electrospray mass spectrometry, and ¹H and ¹³C NMR spectroscopy. These ligands form [2]pseudorotaxanes with α-cyclodextrin (α-CD) and the stability constants have been determined from ¹H NMR titrations in D₂O. The kinetics and mechanism of the assembly and dissociation of a [2]pseudorotaxane in which α-CD has been threaded by the CH₃NH₂(CH₂)₂N(CH₃)(CH₂)₁₂N(CH₃)(CH₂)₂NH₂CH₃²⁺ ligand were determined in aqueous solution using ¹H NMR spectroscopy. A weak inclusion of the dimethylethylenediamine end group precedes the passage of the α-CD onto the hydrophobic dodecamethylene chain.     

Supramolecular interactions and structural transformations in the metal-organic sorbent-acetone nanoreactor system

By the ¹H NMR and Raman spectroscopy data it is shown that in the porous inclusion compound of Zn₂(C₈H₄O₄)₂[(N₂(CH₂)₆))]·n(CH₃)₂CO (n ≈ 0–4.7) acetone molecules exist in two structural forms: ketonic (CH₃)₂CO, for which the ¹H NMR chemical shift value is δ^ket = 0.8 ppm, and enolic CH₃C(O)=CH₂, for which δ^en(OH) = 11 ppm, δ^en(CH₂) = 8.9 ppm, and δ^en(CH₃) = 1.6 ppm are found, the average value over three proton sites being <δ^en> = 5.6 ppm. A sharp difference in chemical shift values for the keto and enol forms of acetone in the inclusion compounds can be assigned to the effect of structural chemical conditions in two types of adsorption centers.     

Photochemical reactions of Re(CO)5Br with Ph2P(CH2) n PPh2 (n = 1, dppm; 2, dppe; 3, dppp)

The new complexes fac-[Re(CO)₃Br{Ph₂P(CH₂) _n PPh₂}] (1a–3a) [(1a), n = 1; (2a), n = 2; (3a), n = 3] and [Re₂(CO)₈Br₂{-Ph₂P(CH₂) _n PPh₂}] (1b–3b) [(1b), n = 1; (2b), n = 2; (3b), n = 3] have been prepared by the photochemical reaction of Re(CO)₅Br with Ph₂P(CH₂) _n PPh₂ (n = 1, dppm; 2, dppe; 3, dppp). The complexes have been characterized by elemental analysis, mass spectroscopy, f.t.-i.r. and ³¹P-[¹H]-n.m.r. spectrometry. The spectroscopic studies suggest cis-chelate bidentate coordination of the ligand in fac-[Re(CO)₃Br{Ph₂P(CH₂) _n PPh₂}] (1a–3a) and cis-bridging bidentate coordination of the ligand between two metals in [Re₂(CO)₈Br₂{cis--Ph₂P(CH₂) _n PPh₂}] (1a–3a).     

以2-(1-吡唑基甲基)吡啶类化合物为配体的羰基钼、钨衍生物的合成及结构

合成了2-[1-(3-叔丁基)吡唑基甲基]吡啶(CH2(Py)(3-ButPz)),并研究了羰基钼(钨)与该配体及其类似物2-(1-吡唑基甲基)吡啶(CH2(Py)(Pz))和2-[1-(3,5-二甲基)吡唑基甲基]吡啶(CH2(Py)(3,5-Me2Pz))的反应,合成了6个含双齿螯合的2-(1-吡唑基甲基)吡啶类配体的四羰基金属衍生物CH2(Py)(3-ButPz)M(CO)4,CH2(Py)(Pz)M(CO)4和CH2(Py)(3,5-Me2Pz)M(CO)4(M=Mo或W)。当用SnCl4处理CH2(Py)(3,5-Me2Pz)M(CO)4时,Sn-Cl键对金属中心发生氧化加成得到2个杂双核金属有机化合物CH2(Py)(3,5-Me2Pz)M(CO)3(Cl)SnCl3。所有新化合物均通过了红外和核磁的表征,CH2(Py)(3-ButPz)W(CO)4和CH2(Py)(3,5-Me2Pz)W(CO)3(Cl)SnCl3的结构还得到了X-射线单晶衍射的确证。用循环伏安法测定了四羰基金属衍生物的电化学性质。     

Polymerization of 1-(trimethylsilyl)-1-propyne homologs containing two silicon atoms by tantalum- and niobium-based catalysts

Polymerization of new 1-(trimethylsilyl)-1-propyne homologs containing two silicon atoms [CH₃C?CSi(CH₃)₂CH₂Si(CH₃)₃ and CH₃C?CSi(CH₃)₂CH₂CH₂Si(CH₃)₃] was investigated by use of Ta and Nb catalysts. CH₃C?CSi(CH₃)₂CH₂Si(CH₃)₃ was polymerized quantitatively by TaCl₅ alone to provide a polymer having molecular weight over 10⁶. CH₃C?CSi(CH₃)₂CH₂CH₂Si(CH₃)₃ was polymerized in good yield by an equimolar mixture of TaCl₅ with an appropriate organometallic cocatalyst such as Ph₄Sn to give a polymer with molecular weight of ca. 4 X 10⁵. Nb catalysts were less active toward these monomers than the corresponding Ta catalysts. These two kinds of polymers had alternating double bonds along the main chain according to IR and ¹³C-NMR spectra. Both polymers were white solids completely soluble in low-polarity solvents like toluene, and solution casting afforded uniform, tough films. These polymers were thermally fairly stable, and their softening points were above 350°C. Films of these polymers showed smaller oxygen permeability coefficients [P = 4 × 10^?9 – 8 × 10^?9 cm³(STP) · cm/(cm²·sec·cmHg)] but larger separation factors [(P/P) = 3.4 – 3.6] than a poly[1-(trimethylsilyl)-1-propyne] film.     

Ionic Transformations in Extremely Nonpolar Fluorous Media: Easily Recoverable Phase‐Transfer Catalysts for Halide‐Substitution Reactions

Solutions of the fluorous alkyl halides R_f8(CH₂)_mX (R_fn=(CF₂)_n?1CF₃; m=2, 3; X=Cl, Br, I) in perfluoromethylcyclohexane or perfluoromethyldecalin are inert towards solid or aqueous NaCl, NaBr, KI, KCN, and NaOAc. However, halide substitution occurs in the presence of fluorous phosphonium salts (R_f8(CH₂)₂)(R_f6(CH₂)₂)₃P⁺X^? (X=I ( 1 ), Br ( 3 )) and (R_f8(CH₂)₂)₄P⁺I^? (10 mol %), which are soluble in the fluorous solvents under the reaction conditions (76–100 °C). Stoichiometric reactions of a) 1 with R_f8(CH₂)₂Br and b) 3 with R_f8(CH₂)₂I were conducted under homogenous conditions in perfluoromethyldecalin at 100 °C and yielded the same R_f8(CH₂)₂I/R_f8(CH₂)₂Br equilibrium ratio (≈60:40). This shows that ionic displacements can take place in extremely nonpolar fluorous phases and suggests a classical phase‐transfer mechanism for the catalyzed reactions. Interestingly, the nonfluorous salt (CH₃(CH₂)₁₁)(CH₃(CH₂)₇)₃P⁺I^? ( 4 ) also catalyzes halide substitutions, but under triphasic conditions with 4 suspended between the lower fluorous and upper aqueous layers. NMR experiments established very low solubilities in both phases, which suggests interfacial catalysis. Catalyst 1 is easily recycled, optimally by simple precipitation onto teflon tape.     

Synthesis of 2‐aminomethylpiperidine ruthenium(II) phosphine complexes and their applications in transfer hydrogenation of aryl ketones

The complex trans,cis‐[RuCl₂(PPh₃)₂(ampi)] (2) was prepared by reaction of RuCl₂(PPh₃)₃ with 2‐aminomethylpiperidine(ampi) (1). [RuCl₂(PPh₂(CH₂)_nPPh₂)(ampi) (n = 3, 4, 5)] (3–5) were synthesized by displacement of two PPh₃ with chelating phosphine ligands. All complexes (2–5) were characterized by ¹ H, ¹³C, ³¹P NMR, IR and UV‐visible spectroscopy and elemental analysis. They were found to be efficient catalysts for transfer hydrogen reactions. Copyright © 2012 John Wiley & Sons, Ltd.     

Polymerization of silicon-containing acetylenes. 5. Polymerization of 1-silyl-1-propynes by TaCl5-based catalysts

Polymerization of homologues of 1-(trimethylsilyl)-1-propyne [CH₃C?CSi(CH₃)₃] was studied. CH₃C?CSi(CH₃)₂(n-C₆H₁₃) ( I ) polymerized with 1 : 1 mixtures of TaCl₅ and organometallic cocatalysts (e.g., Ph₄Sn and Ph₃Bi) to produce in good yields a polymer having a weight-average molecular weight (M _w) over 1 × 10⁶. CH₃C?CSi(CH₃)₂ Ph ( II ) and CH₃C?CSi(C₂H₅)₃ ( III ) formed polymers having M _w's of ～ 5 × 10⁵ in moderate yields in the presence of TaCl₅-based catalysts. In contrast, none of CH₃C?CSi(CH₃)₂(i-C₃H₇), CH₃C? CSi(CH₃)₂(t,-C₄H₉), C₂H₅C?CSi(CH₃)₃, and n,-C₄H₉C?CSi(CH₃)₃ polymerized, which is attributed to the steric effect of the monomers. Some other 1-silyl-1-propynes also failed to polymerize. The three new polymers formed from ( I )–( III ) had the structure \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} [{\rm CCH}_{\rm 3} \hbox{=\hskip-2pt=} {\rm C(SiRR'R''}\rlap{--} ]_n$\end{document} according to IR and ¹³C-NMR spectra. They were white solids, soluble in low-polarity solvents (e.g., toluene and chloroform) and stable enough in air at room temperature.     

Ferrocene-carboxylate coordination complexes bridged by different N-containing ligands

Six new coordination complexes, [Cd(η ²-OOCCH=(CH₃)CFc)₂(bix)]₂·(CH₃OH)_0.5 (1), [Zn(η ²-OOCCH=(CH₃)CFc)(η ¹-OOCCH=(CH₃)CFc)(bix)]₂·(H₂O)_0.5 (2), [Zn(η ²-OOCCH=(CH₃)CFc)₂(pbbm)]₂·(CH₃OH)₂ (3), {[Mn(η ¹-OOCCH=(CH₃)CFc)₂(bbbm)(H₂O)₂]·(CH₃OH)₃}_n (4), {[Cd(η ¹-OOCCH=(CH₃)CFc)₂(bbbm)]·(CH₃OH)₂}_n (5), and [Cd(η ²-OOCCH=(CH₃)CFc)₂(pmbbm)]_n (6) {Fc?=?(η ⁵-C₅H₄)Fe(η ⁵-C₅H₄), bix?=?1,4[bis(imidazol-1-ylmethyl)benzene], pbbm?=?1,1′-[(1,4-propanediyl)bis-1H-benzimidazole], bbbm?=?1,1′-[(1,4-butanediyl)bis-1H-benzimidazole)], pmbbm?=?1,1′-[(1,4-pentanediyl)bis-1H-benzimidazole]}, were prepared and characterized. X-ray crystallographic analysis reveals that 1–3 are dimers bridged by bix and pbbm. Complexes 4–6 are one-dimensional (1-D) structures bridged by bbbm and pmbbm, respectively. Various π–π interactions were discovered in 1–6 that make significant contributions to molecular self-assembly. Solution differential pulse voltammetry of 1–6 indicates that the half-wave potentials of the ferrocenyl moieties in these complexes shift to positive potential compared with that of 3-ferrocenyl-2-crotonic acid.     

Syntheses,crystal structures,and fluorescent properties of 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate ligands

Two new complexes, {[Cd(btec)_0.5(imb)(CH₃OH)]·CH₃OH}_n (1) and {[Cd(btec)_0.5(H₂btec)]·(H₂imb)·2H₂O}_n (2) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, imb = 2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Both complexes exhibit 2-D network structures. In 1, each 1,2,4,5-benzenetetracarboxylate links four Cd²⁺ cations, and each Cd²⁺ cation connects two 1,2,4,5-benzenetetracarboxylates, to form a 2-D layer, with the imb ligands located on each side of the 2-D layer. In 2, there are two kinds of 1,2,4,5-benzenetetracarboxylates in the structure. One kind is completely deprotonated and acts as hexadentate linkers, leading to a 2-D layer. The other kind is only doubly deprotonated and decorates each side of the 2-D layer. In 2, imb is protonated, forming (H₂imb)²⁺ cations that only cocrystallize with the negatively charged Cd coordination polymer ({[Cd(btec)_0.5(H₂btec)]^2?}_n), but does not coordinate to the Cd²⁺ cations. IR spectra, PXRD patterns, thermogravimetric analyses, and fluorescent properties of 1 and 2 have also been determined.     

Beiträge zur chemie des iodpentafluorids teil III. Chelatisierung und strukturisomerie bei α,β-methylierten IOD(V)-α,β-ethandiolat-fluoriden

We report metathetical reactions of IF₅ with series of α,β-trimethylsilylated ethanediolates with increasing numbers of CH₃-groups in α- and β-positions. Short lived intermediates IF₄[OC₂H_4?n(CH₃)_nO]X with X = Si(CH₃)₃ or IF₄ and stable chelates IF₃[OC₂H_4?n(CH₃)_nO] and IF[OC₂H_4?n(CH₃)_nO]₂ (n = 0–4) are observed and characterized. Time and temperature dependence of ¹⁹F-NMR-spectra in relation to degree of methylation, arrangement and stereo-chemistry are discussed referring to previously published mono- and polynuclear I(V)-compounds containing a series of monodentate alcoholates CH_3?n(CH₃)_nO^? and (CH₃)₃CCH₂O^? (n = 0,2,3) [1,2] and of bidentate alcoholates ^?O(CH₂)_nO^? (n = 2,3,4,5,6,12) [1]. In contrast to aliphatic α,β-diolates the aromatic diolates 1,2-C₆H₄(O^?)₂, 1,2-C₆Cl₄(O^?)₂ rapidly undergo redox reactions even at low temperatures.     

Construction of Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,4-benzenedicarboxylate

Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic^2?), [CdCl(bdic)_1/2(imb)₂]_n (1), {[Cd(bdic)(imb)(H₂O)]·DMF·2H₂O}_n (2), and [Cd(bdic)(imb)]·3H₂O}_n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic^2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic^2?(A) and bdic^2?(B) anions link the binuclear [Cd₂(imb)₂(H₂O)₂] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 1–3 exhibit good fluorescence in the solid state at room temperature.     

Silicon‐terminated telechelic oligomers by ADMET chemistry: Synthesis and copolymerization

Methoxydimethylsilane and chlorodimethylsilane‐terminated telechelic polyoctenomer oligomers (POCT) have been prepared by acyclic diene metathesis (ADMET) chemistry using Grubbs' ruthenium Ru(Cl₂)(CHPh)(PCy₃)₂ [Ru] or Schrock's molybdenum Mo(CH CMe₂Ph)(N 2,6 C₆H₃ i Pr₂)(OCMe(CF₃)₂)₂ [Mo] catalysts. These macromolecules have been characterized by FTIR, ¹H‐, ¹³C‐, and ²⁹Si‐NMR spectroscopy. The molecular weight distributions of these polymers have been determined by GPC and vapor pressure osmometry (VPO). The number‐average molecular weight (M_n) values of the telechelomers are dictated by the initial ratio of the monomer to the chain limiter. The termini of these oligomers (M_n = 2000) can undergo a condensation reaction with hydroxy‐terminated poly(dimethylsiloxane) (PDMS) macromonomer (M_n = 3300) [HO Si(CH₃)₂ O { Si(CH₃)₂O }_x  Si(CH₃)₃], producing an ABA‐type block copolymer, as follows: (CH₃)₃SiO [ Si(CH₃)₂O ]_x [ CHCH (CH₂)₆ ]_y [ OSi(CH₃)₂ ]_x OSi(CH₃)₃. The block copolymers were characterized by ¹H‐ and ¹³C‐NMR spectroscopy, VPO, and GPC, as well as elemental analysis, and were determined by VPO to have a M_n of 8600. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 849–856, 1999     

Electronic Effects in X(CH2)nY Homologous Series by NMR and Quantum Chemistry

The ^79,81Br NQR spectra of compounds of the Br(CH₂) _n COOH (n = 1-5) and Br(CH₂) _n COOSi·(CH₃)₃ (n = 1, 2, 4, 5) homologous series were measured at 77 K. The NQR frequencies of compounds of the first series as n increases to 3 and then oscillate. The ³⁵Cl NQR frequencies of Cl(CH₂) _n Cl series molecules, estimated from the Cl3p populations resulting from RHF/6-31G(d) calculations, steadily decrease as n increases from 1 to 10. No oscillation of calculated ³⁵Cl frequencies was revealed for compounds of the latter series (by contrast to experimental observations). The calculation results give no way to deducing the mechanism of the oscillation effect.     

Homometallic glycolates containing hydroxyl functionality for anchoring another metal: synthesis and characterization of heterometallic alkoxide–glycolates of Ti and Zr incorporating Al and Nb

Reaction of Ti(OPrⁱ)₄ with 2-methyl-2,4-pentanediol [HOGOH, where G = CMe₂CH₂CH(Me)] in 1?:?3 M ratio under reflux afforded the monomeric [Ti(OGO)(OGOH)₂] (1), which on further reactions with [Al(OPrⁱ)₃] or [Nb(OPrⁱ)₅] in 1?:?1 and 1?:?2 M ratios afforded heterometallic derivatives, [Ti(OGO)₃{M(OPrⁱ)_n?2}] and [Ti(OGO)₃{M(OPrⁱ)_n?1}₂] [where M = Al (n = 3), Nb (n = 5)], respectively. Similar reactions of Zr(OPrⁱ)₄?PrⁱOH with a number of glycols [HOGOH, where G = CH(Me)CH(Me), CMe₂CMe₂, CMe₂CH₂CH(Me)] yielded dimeric [Zr₂(OGO)₂(OGOH)₄]. [Zr₂(OGO)₆{M(OPrⁱ)_n?2}₂] and [Zr₂(OGO)₄(OGOH)₂M(OPrⁱ)_n?2] [M = Al (n = 3), Ti (n = 4), Nb (n = 5)] were prepared by 1?:?2 and 1?:?1 reactions, respectively, of [Zr₂(OGO)₂(OGOH)₄] with Al(OPrⁱ)₃, Ti(OPrⁱ)₄, or Nb(OPrⁱ)₅. Surprisingly, a 1?:?2 reaction of [VO(OPrⁱ)₃] with 2,2-diethyl-1,3-propanediol in benzene followed a different reaction and produced a neutral tetranuclear derivative [V₄(O)₄(μ-OCH₂CEt₂CH₂O)₂(OCH₂CEt₂CH₂O)₄] (18). All of these derivatives were characterized by elemental analysis, molecular weight measurements, FT-IR, and ¹H NMR (and wherever possible, by ²⁷Al or ⁵¹V NMR) spectroscopic studies. The derivatives [Zr₂(OCMe₂CH₂CH(Me)O)₂(OCMe₂CH₂CH(Me)OH)₄] (9 and 18) were additionally characterized by single-crystal X-ray structure analysis.     

Synthesis and Spectroscopic Characterization of Two Different Types of Heterobimetallic Glycolate Complexes of Niobium(V)

An entirely new class of heterobimetallic homoleptic glycolate complexes of the type Nb(OGO)₃{Ta(OGO)₂} [where G=CMe₂CH₂CH₂CMe₂ (G¹) (3); CMe₂CH₂ CHMe(G²) (4); CHMeCHMe (G³) (5); CH₂CMe₂CH₂ (G⁴) (6); CMe₂CMe₂(G⁵) (7); CH₂CHMeCH₂ (G⁶) (8); CH₂CEt₂CH₂ (G⁷) (9); CH₂CMe(Prⁿ)CH₂ (G⁸) (10)] have been prepared by the reactions of Nb(OGO)₂(OGOH) [G=G¹ (1a); G² (1b); G³ (1c); G⁴ (1d); G⁵ (1e); G⁶ (1f); G⁷ (1g); G⁸ (1h)] with Ta(OGO)₂ (OPrⁱ) (G=G¹ (2a); G² (2b); G³ (2c); G⁴ (2d); G⁵ (2e) G⁶ (2f); G⁷ (2g); G⁸ (2h). In addition to the novel derivatives (2)–(10), our earlier investigations on heterobimetallic glycolate-alkoxide derivatives have been extended to derivatives of the type Nb(OGO) [where M=A1 n=3, G=G³ (11);G⁴ (12); G⁶ (13) G⁷ (14); G^s (15); G⁹=CH₂CH₂CH₂ (16) and M=Ti (n=4, G=G⁴) (17), Zr(n=4,G=G⁴) (18)], which are conveniently prepared by the reactions of metalloligands Nb(OGO)₂(OGOH) [G=G³ (1c); G⁴ (1d); G⁶ (1f); G⁷ (1g); G⁸ (1h); G⁹ (1i)] with different metal alkoxides. All of these new complexes have been characterized by elemental analyses, molecular weight determinations, and spectroscopic (I.r. and ¹H, ²⁷Al-n.m.r.) studies. Structural features of the new derivatives have been elucidated on the basis of molecular weight and spectroscopic data.