1,721,344 research outputs found
Heteroleptic Chini-Type Platinum Clusters: Synthesis and Characterization of Phosphine Derivatives of [Pt3n(CO)6n]2− (n = 2− 4)
No full textC-S and C-Se Bond Formation at Bridging Vinyliminium Ligands in Diiron Complexes
No full textThe vinyliminium complexes [Fe2{μ-η1:η3-C(R)C(R)CN-(Me)2}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, 3a;R=CO2Me,
3b; R = Ph, 3c) were treated with S8 in the presence oftBuLi,
undergoing fragmentation and affording the corresponding
six-membered metallacyclic complexes [Fe(Cp)(CO){SC-(R)=C(R)C(NMe2)S}] (5a–c). Complexes 5a–c result from
cleavage of the diiron precursor and addition of S to the vi-nyliminium ligand to generate a dithiochelating ligand.
Analogous reactions of the vinyliminium complexes [Fe2{μ-η
1:η3-C(R)C(R)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3](R=
Me,3d; R=CO2Me,3e), which contain a Xyl group (Xyl
= 2,6-Me2C6H3) in place of a methyl, displayed a different
outcome. Complex3dafforded the diiron complex [Fe2{μ-η
1:η3-C(Me)=C(CS2)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2](10),
whereas3eled to the formation of the five-membered metalla-cycle [Fe(Cp)(CO){C{N(Me)(Xyl)}C(CO2Me)C(CO2Me)S}]
(11) together with the diiron complex [Fe2{μ-η
1
:η
3
-C-(CO2Me)=C(S)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2](12). The
formation of 10 and 12 implies C–H and C–C cleavage,
respectively, and C–S bond formation without rupture of the
diiron framework. The vinyliminium complexes3a–dand
also [Fe2{μ-η1:η3-C(Et)C(Et)CN(Me)(CH2Ph)}(μ-CO)(CO)-(Cp)2][SO3CF3](3f) reacted with gray selenium in the pres-ence of tBuLi to afford the five-membered metallacycles [Fe(Cp)(CO){C{N(Me)R}C(R)C(R)Se}] (R = R = Me,13a;R
= Me, R =CO2Me,13b;R=Me, R = Ph,13c; R = Xyl, R =
Me,13d;R=CH2Ph, R=Et,13f) in which one Se atom has
been incorporated into the chelating ligand. The X-ray mo-lecular structures of 5a and13a have been determined
Ligand-interchange reactions between M(iv) (M = Ti, V) oxide bis-acetylacetonates and halides of high-valent group 4 and 5 metals. A synthetic and electrochemical study
Full text linkThe reactions of M’O(acac)2[M’ = Ti, V; acac = acetylacetonato anion] with equimolar amounts of MF5
(M = Nb, Ta) in CH2Cl2 afforded Ti(acac)2F2, 1a, and [V(acac)3][MF6] (M = Nb,4a;M=Ta,4b), respectively.
MOF3 (M = Nb, 2a; M=Ta,2b) were co-produced from MF5/TiO(acac)2. The intermediate species [TaF4{OTi(acac)2}2][TaF6], 3, was intercepted in the course of the formation of 1a from TiO(acac)2/TaF5.
NbCl5 reacted with TiO(acac)2 yielding selectively the previously reported [NbO(acac)Cl2]x, 5, and Ti2(acac)2(μ-Cl)2Cl4, 6. Complex 6 was alternatively obtained from the addition of a two-fold excess of TiCl4 to VO(acac)2. The 1 : 1 reactions of TiX4 (X = F, Cl) with TiO(acac)2 in dichloromethane gave Ti(acac)2X2 (X = F,1a; X = Cl, 1b) and TiOX2 (X = F, 7a; X = Cl, 7b). The 1 : 1 combination of TiX4 (X = F, Cl) with VO(acac)2 led to 1a, band VOX2 (X = F, 8a; X = Cl, 8b). The μ-oxido compounds (C6F5)3B–O–M’(acac)2(M’ = Ti, V) underwent fragmentation by [PF6]- in chlorinated solvent, yielding POF3, 9, and [B(C6F5)3F]-, 10, according to NMR studies; 1a and V(acac)3+, respectively, were detected as the metal-containing species. Electrochemical studies were carried out aiming at the full characterization of the products and the observation of possible degradation pathways
Reactions of TaF5 with Activated Arenes. Synthesis of [4-(OH)-3-(OCH3)C6H3CH(=O-H)][4-(OH)-3-(OCH3)C6H3CHO][TaF6], a Rare Example of Protonated Aldehyde
Full text linkThe rare example of protonated aldehyde salt [4-(OH)-3-(OCH3)C6H3CH(@OAH)][4-(OH)-3-(OCH3)C6H3-
CHO][TaF6], 1, was isolated in the solid state by the reaction of 4-hydroxy-3-methoxybenzaldehyde
(vanillin) with TaF5 in dichloromethane. The product 1 was characterized by X-ray diffraction and IR
spectroscopy. The 1:1 reaction of TaF5 with N,N-dimethylaniline in CH2Cl2 cleanly afforded [TaF4(NMe2-
C6H5)2][TaF6], 2, which was identified by NMR spectroscopy. Attempts of crystallization of 2 resulted in
the isolation of the ammonium salt [NHMe2C6H5][TaF6], 3
Coupling of Isocyanide and mu-Aminocarbyne Ligands in Diiron Complexes Promoted by Hydride Addition
No full textThe diiron μ-aminocarbyne complexes [Fe2{μ-CN(Me)(R)}(μ-CO)(CO)(CNR′)(Cp)2][SO3CF3] (R = R′ = Xyl, 2a; R = Xyl, R′ = Me, 2b; R = Xyl, R′ = But, 2c; R = Xyl, R′ = p-C6H4CF3, 2d; R = Me, R′ = Xyl, 2e; Xyl = 2,6-Me2C6H3), containing an isocyanide ligand, have been obtained via CO replacement with the appropriate CNR′ ligand from [Fe2{μ-CN(Me)(R)}(μ-CO)(CO)2(Cp)2][SO3CF3] (R = Xyl, 1a; R = Me, 1b). Compound 2a, upon treatment with NaBH4 and heating at reflux temperature in THF solution, is transformed into the aminocarbene–aldimine [Fe2{μ-η1(C):η1(N)-CN(Me)(Xyl)CH═N(Xyl)}(μ-CO)2(Cp)2] (3) in moderate yield. The reactions occurs via formation of the formimidoyl complex [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(H)═NXyl}(Cp)2] (4a), which has been isolated by reacting 2a with NaBH4 at 0 °C. Likewise, the formimidoyl complex [Fe2{μ-CN(Me)(R)}(μ-CO)(CO){C(H)═NR′}(Cp)2] (R = Xyl, R′ = Me, 4b; R = Me, R′ = Xyl, 4c) have been obtained from 2b,e, respectively, upon reaction with NaBH4, but these complexes do not convert into the aminocarbene–aldimine complexes analogous to 3. Reactions of 2a with other nucleophiles have been investigated, without obtaining any product similar to 3. Complex 2a reacts with NaCN or with LiPPh2, resulting in isocyanide displacement and formation of [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO)(CN)(Cp)2] (5) and [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO)(PPh2)(Cp)2] (6), respectively. Addition of the organocopper reagent Li2CuCNMe2 to 2a affords the acyl complex [Fe2{μ-CN(Me)(Xyl)}(μ-CO){C(O)Me}(CNXyl)(Cp)2] (7). The thiocarbyne complex [Fe2{μ-CSMe}(μ-CO)(CO)(CNXyl)(Cp)2][SO3CF3] (8), which shows analogies with 2a, reacts with NaBH4, affording the carbene derivative [Fe2 μ-{C(SMe)(H)}(μ-CO)(CO)(CNXyl)(Cp)2] (9). The molecular structures of 2a and 3 have been determined by X-ray diffraction studies
The reactivity of molybdenum pentachloride with ethers: routes to the synthesis of MoIVCl4 adducts, Mo(v) chlorido-alkoxides and Mo(v) oxydo-chlorides
No full textThe reactivity of molybdenum pentachloride, 1, with a selection of mono- and diethers was investigated at room temperature in a non-coordinating solvent (dichloromethane). The Mo(IV) complex MoCl4(OMe2)2, 2, was obtained in 75% yield by the reaction of 1 with an excess of Me2O; similarly, MoCl4(κ2-L) [L = EtOCH2CH2OEt, 6a; MeOCH2CH(Me)OMe, 6b] were prepared in good yields by 1 : 1 combination of 1 with the appropriate diether. MoCl5 reacted with OMePh and Et2O affording variable amounts of RCl (R = Me and Et, respectively); MoCl3(OPh)2, 3, was isolated in 60% yield from 1 and OMePh. The reactions of 1 with OMetBu, OtBu(CH=CH2), MeOCH2CH2OCH2Cl and 1,3-dioxane proceeded with non-selective activation of the organic material. The oxido-complexes Mo2O2Cl4(μ-OMe)2(μ-MeOH), 4, and MoOCl3(MeOH)2, 5, were isolated in modest amounts from 1/OMetBu, whereas MoOCl3(κ2-MeOCH2CH2OCH2Cl), 7, was obtained in 32% yield from 1/MeOCH2CH2OCH2Cl. All of the isolated metal products were characterized by spectroscopic and analytical techniques, and by X-ray diffractometry in the cases of 2, 4, 5, 6b and 7. NMR/GC-MS analyses were carried out in order to outline the fragmentation pathways of the organic reactants
The interaction of molybdenum pentachloride with O- and S-heterocycles
No full textThe 1 : 2 molar reactions of MoCl5, in dichloromethane at room temperature, with tetrahydrofuran (thf ),
tetrahydropyran (thp), dioxane and tetrahydrothiophene (tht) afforded, respectively, [Mo(O)Cl3(thf )]2, 1,
and MoCl4(L)2(L = thp, 2; dioxane, 3; tht, 4), in 81–87% yields. The molecular structures of1, 2and4
were ascertained by X-ray diffractometry. DFT and spectroscopic (IR, NMR) studies were carried out in
order to shed light on thermodynamic and kinetic aspects of the reaction pathways
A simple route to thermally-stable salts of pyrrolidinium-2-carbonylchloride
No full textThe chlorination of the carboxylic acid unit of α-aminoacids is an important reaction in organic synthesis, and the resulting compounds are usually seen as reactive intermediate species. Herein we report a straightforward procedure to obtain [MCl6]- salts (M = Nb, 2a; Ta, 2b) of the L-proline-derivative (pyrrolidinium-2-carbonylchloride). These are stable up to 80 °C, in the solid state as well as in organic solvents. The X-ray structures determined for 2a,b include the first example of a crystallographically-characterized α-ammonium-acylchloride
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