A new dithiolene ligand with 3,5-dibromo substituted phenyl groups was designed and synthesized. The protected form of the ligand was reacted with a nickel salt providing neutral Ni(S2C2(3,5-C6H3Br2)2)2 and anionic [Ni(S2C2(3,5-C6H3Br2)2)2]− isolated as a Bu4N+ salt. Both were characterized by UV-visible and IR spectroscopy and compared with the similar known molecular systems. They exhibit intense low-energy transitions that are characteristic of such systems. The electrochemical behavior of these molecules was investigated by cyclic voltammetry.

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A novel fluorinated dendrimer-based nanotechnology platform in (19)F MRI and a new bifunctional DOTA chelate were prepared and characterized. We introduce 2 methods for reducing the (19)F longitudinal relaxation time: (a) Increasing the generation; (b) covalent and noncovalent introduction of Gd(III)-chelates. A new bifunctional Gd(III)-chelate is presented. The investigations of imaging on rats suggest potential importance of the dendrimers in (19)F MRI application.

New substituted dibenzothiophenes have been prepared and characterized. Selective functionalizations utilized substitutions of lithiodibenzothiophenes available from established methodology. New dibenzothiophenes prepared include 2‐(bromomethyl)dibenzothiophene (5), 2‐(thiomethyl)dibenzothiophene (6), 2‐S‐phenylthiomethyldibenzothiophene (24), 2‐S‐(2′‐dibenzothiophenylmethyl)thiomethyldibenzothiophene (25), 2‐S‐methyldibenzothiophene (30), 2‐S‐(p‐bromophenyl)dibenzothiophene (31), and 2‐S‐benzyldibenzothiophene (33). Dibenzothiophenes prepared from 4‐lithiodibenzothiophene include 4‐(bromomethyl)dibenzothiophene (13), 4‐(thiomethyl)dibenzothiophene (14), 4‐S‐(4′‐dibenzothiophenylmethyl)thiomethyldibenzothiophene (26), 4‐S‐(p‐tolyl)dibenzothiophene (34), 4‐S‐methyldibenzothiophene (35), 4‐S‐benzyldibenzothiophene (37), and 4‐S‐(p‐bromophenyl)dibenzothiophene (36). Similarly new 2,8‐disubstituted dibenzothiophenes prepared include 2,8‐bis(thiomethyl)dibenzothiophene (19), 2,8‐bis(S‐benzyl)dibenzothiophene (27), 2,8‐bis(S‐p‐tolyl)dibenzothiophene (28) and 2,8‐bis(S‐methyl)dibenzothiophene (29). The cmr chemical shift data for these dibenzothiophenes are also included.

The bicyclic pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3a) engages in a highly unusual fragmentation in the presence of DDQ. The pyran thiolone, 3a, was synthesized by chlorination of 3,4-dihydro-2H-pyran (1), followed by condensing with CS2 and NaSH. Reaction of 3a with DDQ generates the isomerized pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3b) and 4-benzyl-5-(3-hydroxypropyl)-1,3-dithiole-2-thione (4) via a deep-seated rearrangement. The identity of 3b was confirmed by single crystal X-ray analysis: P21/c, a=5.807(9) Å, b = 12.99(2) Å, c = 11.445(15), β=113.23(6)°. Mechanistic experiments and computational insight is used to explain the likely sequence of events in the highly unusual formation of 4. Collectively, these results establish fundamental reactivity patterns for further research in this area.