Ian Lavender

Preparation and characterisation of the mixed 1,3,2,4-/1,2,3,5-dithiadiazolylium salts and related free radicals; [m- and [p-SNSNC–C6H4–CNSSN]x(x= 2+, ·+ or 2·)

The salts [m- and [p-[graphic omitted]–C6H4–[graphic omitted]][AsF6]2 were prepared (in yields exceeding 90%) by the reaction of [NCC6H4[graphic omitted]][AsF6] with [SNS][AsF6] in liquid SO2 and were recrystallised as MeCN solvates. Partial and complete reduction of these dications (as the dichloride salts) led to the isolation and solid-state characterisation of the paramagnetic radical cations [m- and [p-[graphic omitted]–C6H4–[graphic omitted]]Cl and the diradicals [m- and [p-[graphic omitted]–C6H4–)[graphic omitted]2·. The crystal structure of [p-[graphic omitted]–C6H4–[graphic omitted]][AsF6]2·MeCN shows essentially planar [graphic omitted] and [graphic omitted] rings, rotated by 25.1 and 16.7° respectively from the phenylene ring plane.

The first solid state paramagnetic 1,2,3,5-dithiadiazolyl radical; X-ray crystal structure of [p-NCC6F4CNSSN]˙

The solid state structure of the fluorinated 1,2,3,5-dithiadiazolyl radical [p-NCC6F4[graphic omitted]]· is reported; it is the first dithiadiazolyl radical to retain its paramagnetic character in the solid state.

Dalton communications. Convenient preparations of the mixed 1,3,2,4-/1,2,3,5-dithiadiazolylium salt [SNSNC–C6H4–CNSSN][AsF6]2 and the first mixed free radical, p-[SNSNC–C6H4–CNSSN]2˙

The salt [p-NCC6H4–[graphic omitted]]Cl {prepared by reaction of Li[p-NCC6H4C(NSiMe3)2] with SCl2} was converted into [p-NCC6H4–[graphic omitted]]AsF6(with AgAsF6) and then reacted with [SNS]AsF6 to provide [[graphic omitted]–C6H4–[graphic omitted]][AsF6]2 in 92% recovered yield. Complete reduction of this material produced the first mixed 1,3,2,4-/1,2,3,5-dithiadiazole diradical, [[graphic omitted]–C6H4–[graphic omitted]]2˙.

Reaction of [SNS][AsF6] with Hg(CN)2 and PhHgCN: Preparation and crystal structures of [Hg()2][AsF6]2 and [PhS4N3Ph][AsF6]

Abstract Reaction of Hg(CN) 2 with two equivalents of the salt [SNS][AsF 6 ] provided a high yield (92%) route to the first metallo-dithiadiazolylium salt, [Hg( ) 2 ][AsF 6 ] 2 ( I ). Its structure and reactivity are compared with those of the analogous organic derivatives, [R. ][AsF 6 ]; I initiates the polymerization of tetrahydrofuran and undergoes metathesis reactions but reduction leads to decomposition (forming S 4 N 4 ), whilst oxidation with the halogens provides a novel route to the salts [X. ][AsF 6 ] (X = Cl, Br and I). In contrast, reaction of PhHgCN with [SNS][AsF 6 ] yielded the sulfur-nitrogen chain compound, [PhS 4 N 3 Ph][AsF 6 ] ( II ) with a cation consisting of an alternating S/N chain strung between two phenyl groups.

Use of (NSCl)3 as a Chain-Building Reagent, I: Reaction of ArS3N2Ar with (NSCl)3 in the Presence of AgAsF6 to Form the Chain-Lengthened Product, [ArS4N3Ar] [AsF6]

Reaction of ArS3N2Ar [Ar = Ph, p-O2N.C6H4-], 1, with (NSCl)3 led to the formation of the chain-lengthened products [ArS4N3Ar]Cl, which were converted to the corresponding hexafluorarsenate (V) salts [ArS4N3Ar][AsF6], 2, by metathesis with AgAsF6. The crystal structure of the para-nitrophenyl derivative, 2a, is reported and is monoclinic, space group P21/c;a = 6.1490(12), b = 17.723(4), c = 18.967(4)A, β = 87.99(3)° with D c = 1.94gcm−3, Z = 4 and R1 (2899 unique data) = 0.11. When Ar = o-O2N.C6H4-, the chain-lengthened product could only be achieved in the presence of both (NSCl)3 and AgAsF6. A mechanism is postulated.

The preparation and X-ray crystal structure of the first metal–1,3,2,4-dithiadiazolylium salt, [Hg(CNSNS)2][AsF6]2, a transfer agent for the dithiadiazolylium ring

The reaction of two equivalents of [SNS][AsF6] with Hg(CN)2 yields [Hg([graphic omitted])2][AsF6]21, the first example of a dithiadiazolylium ring bonded to a metal centre via the carbon; the reaction of 1 with iodine and bromine gave the hexafluoroarsenates(V) of [I–[graphic omitted]]+ and previously unreported [Br–[graphic omitted]]+, thereby demonstrating the potential of 1 as a transfer reagent for the dithiadiazolylium cation.

Cycloaddition reactions of [SNS][AsF6] with potassium tricyanomethanide

The reactions of 1, 2 and 3 equivalents of [SNS][AsF6] with K[C(CN)3] in liquid SO2 generated three cycloaddition products (NC)2C[graphic omitted] 1, [(NC)C([graphic omitted])2][AsF6]2 and [C([graphic omitted])3][AsF6]2·SO23. These were characterised by IR spectroscopy, cyclic voltammetry and elemental analysis. Compounds 1 and 3 were further characterised by 14N and 13C NMR, UV/VIS spectroscopy, X-ray crystallography and (for 1) mass spectroscopy. Compound 1 crystallises as polymeric sheets of dithiadiazole units held together through CN ⋯ S interactions and with a dihedral angle of 117.3° between planes. Compound 3 shows three equivalent [graphic omitted] rings attached to a central carbon atom, the dication possessing C3h symmetry. Molecular orbital calculations were used to deduce a probable reaction mechanism.