Multimetallic Alkaline-Earth Hydride Cations

Reactions of dimeric β-diketiminato (BDI) magnesium and calcium hydrides with [(BDI)Mg]+[Al{OC(CF3)3}4]- provide ionic multimetallic hydride derivatives, which have been characterized by single-crystal X-ray diffraction analysis. The exclusively magnesium centered species comprises a cation in which two [(BDI)Mg]+ units are connected by a single μ2-bridging hydride. In contrast, the greater lability of the calcium-containing system is underscored by the isolation of a cyclic heterotrimetallic species in which a CaH2 moiety is coordinated by a molecule of benzene and an aryl substituent of a [{(BDI)Mg}2H]+ cation. The homometallic dimagnesium species displays a greater facility toward reaction with diphenylacetylene than neutral [(BDI)MgH]2, although the resultant crystallographically characterized vinyldimagnesium cation equilibrates into a complex mixture of neutral and ionic species in solution. An initial assessment of both systems for the hydrosilylation of 1-hexene and diphenylacetylene evidences an inferior catalytic performance of [(BDI)MgH]2 in isolation.</p

Facile kinetic induction of a dihydropyridide to pyrrolide ring contraction

A sterically demanding N-aryl carbodiimide reacts with magnesium 1,4-dihydropyridides to initiate heterocyclic ring contraction and pyrrolide formation under unprecedentedly mild conditions.</p

Reactions of bis(tetrazole)phenylenes:Surprising Formation of Vinyl Compounds from Alkyl halides.

The reactions of 1,2-bis(tetrazol-5-yl)benzene (1), 1,3-bis(tetrazol-5-yl)benzene (2), 1,4-bis(tetrazol-5-yl)benzene (3), 1,2-(Bu3SnN4C)2C6H4 (4), 1,3-(Bu3SnN4C)2C6H4 (5) and 1,4-(Bu3SnN4C)2C6H4 (6) with 1,2-dibromoethane were carried out by two different methods in order to synthesise pendant alkyl halide derivatives of the parent bis-tetrazoles. This lead to the formation of several alkyl halide derivatives, substituted at either N1 and N2 on the tetrazole ring, as well as the surprising formation of several vinyl derivatives. The crystal structures of both 1,2-[(2-vinyl)tetrazol-5-yl)]benzene (1-N, 2-N’) (1b) and 1,3-bis[(2-bromoethyl)tetrazol-5-yl]benzene (2-N, 2-N’) (5d) are discussed

Synthesis and spectroscopic characterization of new mixed-metal, mixed-chalcogenide clusters [Fe<SUB>2</SUB>W(CO)<SUB>10</SUB>(μ<SUP>3</SUP>-Se)(μ<SUP>3</SUP>-E)](E = Te or S). Structures of [Fe<SUB>2</SUB>M(CO)<SUB>10</SUB>(μ<SUP>3</SUP>-Se)(μ<SUP>3</SUP>-E)](M = W, E = Se or Te; M = Mo, E = Se)

The room-temperature reaction of [Fe2(CO)6(μ-SeTe)] and [Fe2(CO)6(μ-SSe)] with freshly prepared [W(CO)5(thf)](thf = tetrahydrofuran) yielded the new mixed-metal, mixed-chalcogenide clusters [Fe2W(CO)10(μ3-Se)(μ3-E)](E = Te 1 or S 2). Compounds 1 and 2 were characterized by IR and 13C, 77Se and 125Te NMR spectroscopy. The crystal structure of 1 was elucidated by X-ray diffraction methods. The previously reported compounds [Fe2W(CO)10(μ3-Se)2]3 and [Fe2Mo(CO)10(μ3-Se)2]4 were further characterized by 77Se NMR spectroscopy and single-crystal X-ray analysis. Clusters 1, 3 and 4 are isostructural and isomorphous (in the solid state). The structure consists of square-pyramidal Fe2WSeTe, Fe2WSe2 and Fe2MoSe2 cores respectively, and in each case the heterometal atom (W for 1 and 3 and Mo for 4) occupies the apical site

Room temperature regioselective catalytic hydrodefluorination of fluoroarenes with trans-[Ru(NHC)4H2] through a concerted nucleophilic Ru−H attack pathway

The authors acknowledge the EPSRC (grant EP/J009962/1, DTA) for financial supportThe efficient and highly selective room temperature hydrodefluorination (HDF) of fluoroarenes by the trans-[Ru(IMe4)4H2] catalyst, 3 , is reported. Mechanistic studies show 3 acts directly in catalysis without any ligand dissociation and DFT calculations indicate a concerted nucleophilic attack mechanism. The calculations fully account for the observed selectivities which corroborate earlier predictions regarding the selectivity of HDF.PostprintPeer reviewe

Alkaline-Earth Derivatives of Diphenylphosphine-Borane

Treatment of β-diketiminato (BDI = HC{C(CH3)Ndipp)}2 where dipp = 2,6-iPr2C6H3) magnesium butyl [(BDI)MgBu] (I) and calcium hexamethyldisilazide [(BDI)Ca{N(SiMe3)2}] (II) complexes with equimolar quantities of diphenylphosphine-borane, Ph2PH·BH3, results in the formation of the respective alkaline earth (Ae) phosphidoborane derivatives [(BDI)Mg(Ph2PBH3)]2 (6a) and [(BDI)Ca(Ph2PBH3)] (7a). Although satisfactory single crystals of 7a could not be obtained, 6a was crystallographically characterized and both compounds display similar NMR spectra. The dimeric Ae-hydride complexes [(BDI)AeH]2 (IIIa, Ae = Mg; IIIb, Ae = Ca) react with substoichiometric quantities of Ph2PH·BH3, allowing the crystallization of the dimeric Mg and trimeric Ca phosphidoborane species [(BDI)Mg(H)(H3BPPh2)Mg(BDI)] (8) and [{(BDI)Ca}3(H)(H3BPPh2)2] (9). In the absence of coordinating Lewis bases, compounds 6a, 7a, 8, and 9 display dynamic solution-state behavior (in benzene and toluene), while addition of THF furnishes the monomeric adducts [(BDI)Mg(H3BPPh2)·THF] (6b) and [(BDI)Ca(H3BPPh2)·THF] (7b). Addition of Ph2PH·BH3 to compound 6a results in BH3 transfer to eliminate Ph2PH and generate the phosphinodiboronate complex [(BDI)Mg{(H3B)2PPh2}]2 (10) in preference to dehydrocoupling of the phosphidoborane and phosphine-borane reagents.</p