The reactivity of [MoS(4)](2-) (1) toward PMe(3) was explored in the presence and absence of proton donors. Whereas MeCN solutions of (Et(4)N)(2)[MoS(4)] and PMe(3) are stable, in the presence of H(2)S such solutions catalyze formation of H(2) and SPMe(3). Addition of NH(4+) to such solutions afforded MoS(2)(PMe(3))(4) (2), which can be prepared directly from (NH(4))(2)[1]. Compound 2 is reactive toward thiols via a process proposed to involve the initial dissociation of one PMe(3) ligand, a hypothesis supported by the relative inertness of trans-MoS(2)(dmpe)(2). Benzene solutions of 2 react with EtSH to give Mo(2)(mu-S)(mu-SH)(PMe(3))(4)(SEt)(3) (3Et). Analogous reactions with thiocresol (MeC(6)H(4)SH) and H(2)S gave Mo(2)(mu-S)(mu-SH)(PMe(3))(4)(SR)(3) (R = tol, H). Crystallographic analyses of 3Et, 3H, and 3tol indicate dinuclear species with seven terminal ligands and a Mo(2)(mu-SR)(mu-S) core (r(Mo)(-)(Mo) = 2.748(1) A). From reaction mixtures leading to 3Et from 2, we obtained the intermediate Mo(IV)(2)(mu-S)(2)(SEt)(4)(PMe(3))(2) (4), an edge-shared bis(trigonal pyramidal) structure. Compounds 3H and 3Et react further with H(2)S to give Mo(4)(mu(2)-S)(4)(mu(3)-S)(2)(PMe(3))(6)(SH)(2) (5H) and Mo(4)(mu(2)-S)(4)(mu(3)-S)(2)(PMe(3))(6)(SEt)(2) (5Et), respectively. Analogously, W(4)(mu(2)-S)(4)(mu(3)-S)(2)(PMe(3))(6)(SH)(2) was synthesized from a methanol solution of (NH(4))(2)WS(4) with H(2)S and PMe(3). A highly accurate crystallographic analysis of (NH(4))(2)MoS(4) (R(1) = 0.0193) indicates several weak NH.S interactions. 相似文献
By using deuterium labelled compounds and collisional activation spectra the mechanism of the unusually intensive HCl elimination from 2-(β-chloroalkyl)benzoic acid methyl ester as well as the structure of the product ion have been elucidated. It can be shown that the structure of the stable ion (lifetime τ~10?5 s) is best represented by 2-vinyl benzoic acid methyl ester whereas the reactive ion (lifetime τ<10?6 s) at least partially rearranges to a cyclic ion. The hydrogen chloride elimination from 2-(β-chloroalkyl)benzoic acid is apparently a simple 1,2 process. A closer examination reveals that the reaction represents a further example of an unusual neighbouring group participation of the ester function. 相似文献
New Compounds with Garnet Structure. VI. Vanadates The preparation of vanadate-garnets of the following three types is reported: (I) {Na3}[B2III](V3)O12 (BIII = Cr, Sc), (II) {LiCa2}[B2II](V3)O12 (BII = Mg), (III) {Ca2AIII}[Li2] (V3)O12 (AIII = In, Sc). The Cr-compound of type (I) decomposes above 690°C into a mixture of Cr2O3 and NaVO3. The analogous Fe-compound decomposes in a similar way already at 400°C; therefore the preparation by solid state reaction is not possible. Employing larger BIII-ions (Y, Yb, Lu) no garnets of type (I), but mixtures of BIIIVO4 (zircon structure) and Na3BIIIV2O8 are formed. Garnets of type (II) do not exist, when BII are Co and Ni. Mixtures of {Ca3}[LiBII](V3)O12 (garnet structure), LiBIIVO4 (spinel structure) and B3II(VO4)2 are formed. With type (III) for AIII = Y reaction occurs forming a mixture of YVO4, Ca3(VO4)2 and Li3VO4. 相似文献
By means of collisional activation mass spectrometry and semi-empirical molecular orbital calculations (MNDO) it is shown that the [C2H5O2]+ ions from metastable molecular ions of n-pentanoic and hexanoic acid have the structure of carbonyl protonated acetic acid [CH3C(OH)2]+. The MNDO calculated geometries of this ion and some other isomeric forms are given together with the ΔHf0 values. 相似文献
The mass spectrometric investigation of specifically deuterium and 13C labelled 2-trimethylsilyl-l-phenoxyethanes proves that the dissociative ionization of β-silyl-substituted ethane derivatives (loss of PhO?; p-CH3C6H4O?; and C4H?9 from PhOCH2CH2SiMe3, p-MeC6H4OCH2CH2SiMe3 and CH3CH2CH(CH3)CH2-CH2SiMe3, respectively) yields the non-classical bridge ethylene trimethylsilanium ion and not the open-chain isomer. Other stable C5H13Si+? ions, characterised by collisional activation mass spectrometry, are the dimethyl n-propyl silicenium ion and the l-trimethylsilyl ethyl cation, both generated from the molecular ions of CH3CH2CH2Si(Cl)Me2 and CH3CH(Cl)SiMe3 via unimolecular loss of Cl?. 相似文献
In this paper, we present a summary of our work on highly photostable supramolecular ruthenium complexes, which may be incorporated into more complex systems for artificial solar energy conversion. We have used supramolecular chemistry and photochemistry to synthesize highly photostable ruthenium bipyridine coronates and a bipyridazine podate complex and to enhance photoelectron-transfer reactions in physical model systems for artificial photosynthesis. The recent progress of covalent and non-covalent sensitizer-relay assemblies for highly efficient photoelectron transfer is described.
A detailed mechanistic investigation of the binding behavior of cationic species to crow-ether-modified bipyridine derivatives is presented as an example of supramolecular binding in systems for photoelectron transfer. The host properties of the free ligands and the derived bis-heteroleptic ruthenium complexes are compared using UV—visible, luminescence quenching and proton nuclear magnetic resonance titrations. The combination of these three methods confirms that supramolecular binding of cations and the electron relay methylviologen (MV2+) to the complexes can be observed. The binding constants determined are of the order of (1–6) × 104 1 mol−1 for the crown-ether ruthenium complexes and 1 × 102−4 × 103 1 mol−3 for the crown-ether ligands. Single-photon-counting (SPC) investigations give strong indications for the coexistence of different binding mechanisms. The kinetic scheme of Yekta et al. has been adapted to interpret the binding mechanism. 相似文献
The reactions of Group 8, 9 and 10 monocations with phosphane were studied under single-collision conditions in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Fe(+) is completely unreactive, Co(+) reacts slowly and shows both adduct formation and P-H bond activation, and Ni(+) reacts slowly as well but shows adduct formation only. In contrast to their first-row congeners, the investigated second- and third-row transition metal monocations show facile P-H bond activations. Remarkably, extensive dehydrogenations of the collision complexes yield cations MPH(+), MP(2) (+), MP(3)H(+), MP(4) (+) and so on. Exceptional behaviour is shown by the two d(9) cations palladium (whose "dehydrogenation power" is rather limited) and platinum (which gives rise to a great manifold of only partially dehydrogenated species as well). Collision-induced dissociation experiments suggest that P(2) and PH units are formed as ligands. 相似文献