[Co/Fe(α-Alkyl-tpdt)2]x-: Alkyl-Substituted Cobalt and Iron Bis-dithiolenethiophenic Complexes.

Tetraphenylphosphonium salts of Co and Fe complexes with alkyl-substituted, tert-butyl (tb), and isopropyl (dp) 2,3-thiophenedithiolate (α-tpdt) ligands, namely, TPP[Co(α-tb-tpdt)2] (3), TPP2[Fe(α-tb-tpdt)2]2 (4a-b), TPP[Co(α-dp-tpdt)2] (5), and TPP[Fe(α-dp-tpdt)2] (6) were prepared and characterized by cyclic voltammetry, single crystal X-ray diffraction, magnetic susceptibility measurements, and 57Fe Mössbauer spectroscopy. Compound 3 and 5 are isostructural with their Au and Ni analogues with a square-planar coordination geometry. Compound 4 presents two polymorphs (4a-b) both showing a Fe(III) bisdithiolene dimerization. The magnetic susceptibility of 3 and 5 exhibits behavior dominated by antiferromagnetic interactions, with room-temperature magnetic moments of 3.40 and 3.36 µB, respectively, indicating that these square-planar Co(III) complexes assume an intermediate spin electronic configuration (S = 1) as supported by multiconfigurational and DFT calculations.

Gold and Nickel Extended Thiophenic-TTF Bisdithiolene Complexes.

Gold and nickel bisdithiolene complexes with methyl and tert-butyl substituted thiophenetetrathiafulavalenedithiolate ligands (α-mtdt and α-tbtdt) were prepared and characterized. These complexes were obtained, under anaerobic conditions, as tetrabutylammonium salts. The diamagnetic gold monoanion (n-Bu4N)[Au(α-mtdt)2] (3) and nickel dianionic species (n-Bu4N)x[Ni(α-mtdt)2] (x = 1,2) (4) were similar to the related non-substituted extended thiophenic-TTF (TTF = tetrathiafulvalene) bisdithiolenes. However the introduction of the large, bulky substituent tert-butyl, led to the formation of a Au (I) dinuclear complex, (n-Bu4N)2[Au2(α-tbtdt)2] (5). The neutral methyl substituted gold and nickel complexes were easily obtained through air or iodine exposure as polycrystalline or amorphous fine powder. [Au(α-mtdt)2] (6) and [Ni(α-mtdt)2] (7) polycrystalline samples display properties of a metallic system with a room temperature electrical conductivity of 0.32 S/cm and ≈4 S/cm and a thermoelectric power of ≈5 µV/K and ≈32 µV/K, respectively. While [Au(α-mtdt)2] (6) presented a Pauli-like magnetic susceptibility typical of conducting systems, in [Ni(α-mtdt)2] (7) large magnetic susceptibilities indicative of high spin states were observed. Both electric transport properties and magnetic properties for gold and nickel [M(α-mtdt)2] are indicative that these compounds are single component molecular conductors.

TTFs nonsymmetrically fused with alkylthiophenic moieties.

Two new dithiolene ligand precursors, containing fused TTF and alkyl thiophenic moieties 3,3'-{[2-(5-(tert-butyl)thieno[2,3-d][1,3]dithiol-2-ylidene)-1,3-dithiole-4,5-diyl]bis[sulfanediyl]}dipropanenitrile (α-tbtdt, 1), and 3,3'-{[2-(5-methylthieno[2,3-d][1,3]dithiol-2-ylidene)-1,3-dithiole-4,5-diyl]bis[sulfanediyl]}dipropanenitrile (α-mtdt, 2), were synthesized and characterized. The electrochemical properties of these electronic donors were studied by cyclic voltammetry (CV) in dichloromethane. Both compounds show two quasi-reversible oxidation processes, versus Ag/AgCl, typical of TTF donors at E (1) 1/2 = 279 V and E (2) 1/2 = 680 V for 1 and E (1) 1/2 = 304 V and E (2) 1/2 = 716 V in the case of 2. The single-crystal X-ray structure of 1 and of a charge transfer salt of 2, (α-mtdt)[Au(mnt)2] (3), are reported.

Fast synthesis of N-acylhydrazones employing a microwave assisted neat protocol.

A variety of N-acylhydrazones were synthesized under microwave irradiation within 2.5-10 min, starting from benzo, salicyloyl, and isonicotinic hydrazides. The protocol developed employs microwave irradiation in the absence of solvents and catalysts, leading to high yields. The results are reproducible in a 500 mg to 5 g scale.

Contrasting behavior in azide pyrolyses: an investigation of the thermal decompositions of methyl azidoformate, ethyl azidoformate and 2-azido-N, N-dimethylacetamide by ultraviolet photoelectron spectroscopy and matrix isolation infrared spectroscopy.

The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCH=NH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.