1a,11b-dihydrobenz[5,6]anthr[1,2-B]azirine. A non k-region polycyclic arene imine

The synthesis of the title compound 9 is described. Benz[a]anthracene 8,9-oxide (6) was reacted with sodium azide in aqueous acetone and the trans-9-azido-8,9-dihydrobenz[a]anthr-8-ol (7), so formed, was cyclized by tri-n-butylphosphine. Attempts to dehydrogenate 10,11-dihydrobenz[a]anthracene 8,9-imine (4) with DDQ or by allylic bromination followed by base assisted dehydrobromination was unsuccessful. The N-tosyl derivative of 4, prepared from the free imine, N,O-bis(trimethylsilyl)acetamide and tosyl chloride underwent rapid aziridine-ring cleavage by the silylating agent to give trans-8,9,10,11-tetrahydro-8-(4-methyl)benzensulfon-amido-9- [(trimethyl)oxy]benz[a]anthracene (10).     

Use of a kinetic energy orifice as a probe of metastable dissociation in Fourier transform ion cyclotron resonance mass spectrometry

Although Fourier transform ion cyclotron resonance mass spectrometry is a powerful tool in the qualitative observation of gas phase reactions, ion detection is on the millisecond time scale, orders of magnitude longer than typically found when using a sector instrument. Observations of short-lived species such as chemically activated adduct ions can be accomplished using selective ion excitation as a probe of intermediate lifetime. Whereas ion elimination has been shown to be effective in monitoring ion lifetimes on the microsecond time scale, problems associated with detecting ions produced with high kinetic energies limits the technique. Use of a kinetic energy orifice as an ion skimmer effectively eliminates ions near the center of the ion cell at relatively low kinetic energies. By modifying a single section cell to include a kinetic energy orifice, the lifetimes of chemically activated adduct ions have been investigated.     

Selective fluorination on tertiary carbon-hydrogen single bonds in the aliphatic series

Fluorine acts as an electrophile and, as such, reacts with remote and unactivated tertiary hydrogens in aliphatic alcohols and acids, resulting in the corresponding fluorine derivatives.     

Experimental and computational exploration of the dynamic behavior of (PNP)BF2, a boron compound supported by an amido/bis(phosphine) pincer ligand

The diarylamido/bis(phosphine) PNP pincer ligand (2-(i)Pr(2)P-4-MeC(6)H(3))(2)N has been evaluated as a scaffold for supporting a BF(2) fragment. Compound (PNP)BF(2) (6) was prepared by simple metathesis of (PNP)Li (5) with Me(2)SBF(3). NMR spectra of 6 in solution are of apparent C(2) symmetry, suggestive of a symmetric environment about boron. However, a combination of X-ray structural studies, low-temperature NMR investigations, and DFT calculations consistently establish that the ground state of this molecule contains a classical four-coordinate boron with a PNBF(2) coordination environment, with one phosphine donor in PNP remaining "free". Fortuitous formation of a single crystal of (PNP)BF(2)·HBF(4) (7), in which the "free" phosphine is protonated, furnished another structure containing the same PNBF(2) environment about boron for comparison and the two PNBF(2) environments in 6 and 7 are virtually identical. DFT studies on several other diarylamido/bis(phosphine) pincer (PNP)BF(2) systems were carried out and all displayed a similar four coordinate PNBF(2) environment in the ground state structures. The symmetric appearance of the room-temperature NMR spectra is explained by the rapid interconversion between two degenerate four-coordinate, C(1)-symmetric ground-state forms. Lineshape analysis of the (1)H and (19)F NMR spectra over a temperature range of 180-243 K yielded the activation parameters ΔH(?) = 8.1(3) kcal mol(-1) and ΔS(?) = -6.0(15) eu, which are broadly consistent with the calculated values. Calculations indicate that the exchange of phosphine donors at the boron center proceeds by an intrinsically dissociative mechanism.     

Silver(I) complexes of 9-anthracenecarboxylic acid and imidazoles: synthesis, structure and antimicrobial activity

[Ag(2)(9-aca)(2)] (1) (9-acaH = 9-anthracenecarboxylic acid) reacts with a series of imidazoles to give [Ag(imidH)(2.3)(CH(3)CN)(0.7)](9-aca) (3), [Ag(6)(imidH)(4)(9-aca)(6)(MeOH)(2)] (4), {[Ag(1-Me-imid)(2)](2)[Ag(4)(9-aca)(6)]} (5), {[Ag(1-Bu-imid)(2)](2)[Ag(4)(9-aca)(6)]} (6) and [Ag(apim)](9-aca)·H(2)O (7) (imidH = imidazole; 1-Me-imid = 1-methylimidazole; 1-Bu-imid = 1-butylimidazole; apim = 1-(3-aminopropyl)imidazole). The mononuclear complex 3, hexanuclear 4-6, and polymeric 7, were all characterised using X-ray crystallography. While many of the complexes possess excellent in vitro antifungal and antibacterial activities they are, unanimously, more effective against fungal cells. The insect, Galleria mellonella, can survive high doses of the Ag(i) complexes administered in vivo, and a number of the complexes offer significant protection to larvae infected with a lethal dose of pathogenic Candida albicans cells.