Crystal structures of five 1-alkyl-4-aryl-1,2,4-triazol-1-ium halide salts.

The asymmetric units for the salts 4-(4-fluoro-phen-yl)-1-isopropyl-1,2,4-triazol-1-ium iodide, C11H13FN3 (+)·I(-), (1), 1-isopropyl-4-(4-methyl-phen-yl)-1,2,4-triazol-1-ium iodide, C12H16N3 (+)·I(-), (2), 1-isopropyl-4-phenyl-1,2,4-triazol-1-ium iodide, C11H14N3 (+)·I(-), (3), and 1-methyl-4-phenyl-1,2,4-triazol-1-ium iodide, C9H10N3 (+)·I(-), (4), contain one cation and one iodide ion, whereas in 1-benzyl-4-phenyl-1,2,4-triazol-1-ium bromide monohydrate, C15H14N3 (+)·Br(-)·H2O, (5), there is an additional single water mol-ecule. There is a predominant C-H⋯X(halide) inter-action for all salts, resulting in a two-dimensional extended sheet network between the triazolium cation and the halide ions. For salts with para-substitution on the aryl ring, there is an additional π-anion inter-action between a triazolium carbon and iodide displayed by the layers. For salts without the para-substitution on the aryl ring, the π-π inter-actions are between the triazolium and aryl rings. The melting points of these salts agree with the predicted substituent inductive effects.

Synthesis of a phosphapyracene via metal-mediated cyclization: structural and reactivity effects of acenaphthene precursors.

Metal-mediated synthesis of a new heterocycle, 1-phenyl-phosphapyracene (Ph-4, Ph-PyraPhos), by tandem phosphination/cyclization of peri-substituted 5-bromo-6-chloromethylacenaphthene (3) was investigated for comparison to Pt-catalyzed formation of 1-phosphaacenaphthenes (2, AcePhos) from the analogous naphthalene precursor (1). Reaction of PH2Ph with , NaOSiMe3 and a Cu catalyst gave ; a Pt catalyst yielded PHPh(CH2Ar) (Ph-11, Ar = 5-Br-acenaphthyl). Deprotonation of a complex of this secondary phosphine, [Pt((R,R)-Me-DuPhos)(Ph)(PHPh(CH2Ar))][PF6] (17), generated the phosphido intermediate Pt((R,R)-Me-DuPhos)(Ph)(PPhCH2Ar) (Ph-8), which cyclized to give [Pt((R,R)-Me-DuPhos)(Ph)(Ph-PyraPhos)][PF6] (18). Treatment of P-8 with silver triflate gave 18 and the cyclometalated phosphine complex [Pt((R,R)-Me-DuPhos)(κ(2)-(P,C)-5-Ph2PCH2-6-C12H8)][PF6] (21), which might form via Pt(iv) intermediates. The effects of the added "ace" bridge on structure and reactivity are discussed.

Crystal structures of 2,6-bis-[(1H-1,2,4-triazol-1-yl)meth-yl]pyridine and 1,1-[pyridine-2,6-diylbis(methyl-ene)]bis-(4-methyl-1H-1,2,4-triazol-4-ium) iodide triiodide.

In the structures of the 2,6-bis-(1,2,4-triazoly-3-yl)methyl-substituted pyridine compound, C11H11N7, (I) and the iodide triiodide salt, C13H17N7 (2+)·I(-)·I3 (-), (II), the dihedral angles between the two triazole rings and the pyridine ring are 66.4 (1) and 74.6 (1)° in (I), and 68.4 (2)° in (II), in which the dication lies across a crystallographic mirror plane. The overall packing structure for (I) is two-dimensional with the layers lying parallel to the (001) plane. In (II), the triiodide anion lies within the mirror plane, occupying the space between the two triazole substituent groups and was found to have minor disorder [occupancy ratio 0.9761 (9):0.0239 (9)]. The overall packing of structure (II) can be described as two-dimensional with the layers stacking parallel to the (001) plane. In the crystal, the predominant inter-molecular inter-actions in (I) and (II) involve the acidic hydrogen atom in the third position of the triazole ring, with either the triazole N-atom acceptor in weak C-H⋯N hydrogen bonds in (I), or with halide counter-ions through C-H⋯I inter-actions, in (II).

Highly volatile alkaline earth metal fluoroalkoxides.

The synthetic strategies, structural comparison, and thermal gravimetric analyses for a novel family of alkaline earth metal perfluoro-tert-butoxides (PFTB) are presented. The isolated complexes follow the general formula, [Ae(PFTB)(2)(d)(x)]; (1a, Ae = Mg, d = THF, x = 2; 1b, Ae = Ca, d = THF, x = 4; 1c, Ae = Sr, d = THF, x = 4; 1d, Ae = Ba, d = THF, x = 4; 2a, Ae = Mg, d = DME, x = 1; 2b, Ae = Ca, d = DME, x = 2; 2c, Ae = Sr, d = DME, x = 2; 2d, Ae = Ba, d = DME, x = 3; 3a, Ae = Mg, d = diglyme, x = 1; 3b, Ae = Ca, d = diglyme, x = 2; 3c, Ae = Sr, d = diglyme, x = 2; 3d, Ae = Ba, d = diglyme, x = 2; THF = tetrahydrofuran, DME = 1,2-dimethoxyethane) where the crystallographically characterized compounds display either a cis or trans conformations in octahedral or pseudo-octahedral environments. Alkane elimination (Mg), direct metalation via ammonia activation (Ca, Sr, Ba), and transamination (Ca, Sr, Ba) methods yielded the target compounds in moderate to good yields. Structural studies of select compounds showed all compounds to be monomeric with varying degrees of co-ligand coordination, possibly explaining some of the observed physical properties. Thermal gravimetric analyses of the compounds shows sublimation at low temperatures, associated with minimal residue, making this family of fluoroalkoxides promising candidates for metal organic chemical vapor deposition (MOCVD).

When VSEPR fails: experimental and theoretical investigations of the behavior of alkaline-earth-metal acetylides.

The synthesis, structural, and spectral characterization as well as a theoretical study of a family of alkaline-earth-metal acetylides provides insights into synthetic access and the structural and bonding characteristics of this group of highly reactive compounds. Based on our earlier communication that reported unusual geometry for a family of triphenylsilyl-substituted alkaline-earth-metal acetylides, we herein present our studies on an expanded family of target derivatives, providing experimental and theoretical data to offer new insights into the intensively debated theme of structural chemistry in heavy alkaline-earth-metal chemistry.

Platinum-catalyzed enantioselective tandem alkylation/arylation of primary phosphines. Asymmetric synthesis of P-stereogenic 1-phosphaacenaphthenes.

Enantioselective tandem alkylation/arylation of primary phosphines with 1-bromo-8-chloromethylnaphthalene catalyzed by Pt(DuPhos) complexes gave P-stereogenic 1-phosphaacenaphthenes (AcePhos) in up to 74% ee. Diastereoselective formation of four P-C bonds in one pot with bis(primary) phosphines gave C2-symmetric diphosphines, including the o-phenylene derivative DuAcePhos, for which the rac isomer was formed with high enantioselectivity. These reactions, which appear to proceed via an unusual metal-mediated nucleophilic aromatic substitution pathway, yield a new class of heterocycles with potential applications in asymmetric catalysis.

A unique heterobimetallic benzyl calciate--an organometallic mixed-metal species involving a heavy alkaline-earth metal.

A co-complexation reaction utilizing homometallic benzylcalcium and benzyllithium affords a rare example of a heterobimetallic benzyl calciate.