Tosha M. Barclay

Synthesis and coordination chemistry of a water-soluble verdazyl radical. structures and magnetic properties of M(H2O)2(vdCO2)2·2H2O (M = Co, Ni; vdCO2 = 1,5-dimethyl-6-oxo-verdazyl-3-carboxylate)

The synthesis of a verdazyl radical with a carboxylate substituent renders the radical highly soluble in water, thereby permitting the aqueous synthesis of Ni(II) and Co(II) verdazyl complexes which have been structurally and magnetically characterized.

Structure and magnetic properties of a nickel(II) complex of a tridentate verdazyl radical: strong ferromagnetic metal-radical exchange coupling

Magnetic susceptibility measurements on a structurally characterized nickel(II) complex of a tridentate verdazyl radical indicate very strong ferromagnetic Ni–verdazyl intramolecular exchange interactions (J > +200 cm−1).

A bis(1,2,3-dithiazole) charge transfer salt with 2 : 1 stoichiometry; inhibition of association and generation of slipped -stacks

The first example of a charge transfer salt of a benzo-bridged bis(1,2,3-dithiazole) with 2 : 1 stoichiometry is reported; the steric bulk of the chlorines at the 3,6-positions of the benzene ring induces slipped -stacks of dimer radical cations

A bimodal dithiadiazolyl diradical: crystal structure and magnetic properties of the 2,2′-dimethylbiphenylene bridged derivative

The two termini of the torsionally strained dithiadiazolyl diradical S2N2C–C6H3Me–MeC6H3–CN2S2 3 possess different solid state structural environments; the bulk magnetic susceptibility of 3 is interpreted in terms of the distinct properties of the two radical centres.

Sterically protected 1,2,3-dithiazolyl radicals: preparation and structural characterization of 4-chloro-5-pentafluorophenyl-1,2,3-dithiazolyl

Steric protection afforded by a pentafluorophenyl group at the 5-position facilitates the first isolation and structural characterization of a monocyclic 1,2,3-dithiazolyl as its S–S bonded dimer.

Synthesis, structure and electrochemistry of isomeric nickel(II) complexes of a [9]ane fused cyclam macrotricycle: evidence for a stable trans-IV and a redox induced rearrangement in a trans-I conformation.

The macrotricyclic ligand, 1,11-dithia-4,8,14,18-tetraaza-[5,2,2,5]-eicosane, L3 has been synthesized from cyclam. Both the cis- and the trans- isomers of the Ni(ii) complexes have been prepared and characterized by single crystal X-ray crystallography. In the cis-[Ni(trans-I, syn-L3)](Cl(2))·4H(2)O, the syn-isomer of L3 is present in which the cyclam ring adopts a trans-I stereochemistry. Crystal structure data (Pna2(1), tetragonal, a = 17.450(3), b = 12.188(2), c = 11.897(2) Å, V = 2530.2(8) Å(3), R(1) = 0.032 and wR(2) = 0.078) indicate that two of the Ni-N distances, Ni-N(4) = 2.164(3) Å and Ni-N(2) = 2.179(3) Å are longer than Ni-N(1) = 2.100(3) Å and Ni-N(3) = 2.101(3) Å. The Ni-S distances, 2.4265(11) Å and 2.4512(11) Å, are similar to lengths observed in many thioether complexes. The cyclic voltammogram for the Ni(2+/3+) redox couple of the cis-complex is scan rate dependent. Although quasi-reversible at a scan rate of 1000 mV s(-1), when the scan rate is lowered below 100 mV s(-1) the redox couple shows chemical irreversibility. There is evidence for rearrangement of the inner coordination sphere and adsorption of the oxidized species onto the Pt electrode. However, there is no evidence to suggest that isomerization of the cis- to the trans-complex occurs. Consistent with this electrochemical behavior, a time-dependent change in the ESR spectrum for the Ni(iii) species was also observed. A mechanism is proposed where through dissociation of a thioether donor and subsequent substitution of a solvent CH(3)CN, the trans-I conformation changes from a cis-type coordination to a trans-mode. In the trans-[Ni(trans-IV, anti-L3)](ClO(4))(2) complex, the anti-form of L3 is present where the cyclam moiety adopts the rare trans-IV stereochemistry. The trans-complex (C(2)/(c), monoclinic, a = 22.382(9), b = 10.118(2), c = 14.300(3) Å, V = 2493.3(13) Å(3), R(1) = 0.051 and wR(2) = 0.142) is a minor product with all Ni-N distances at 2.124(4) Å and Ni-S distances at 2.5321(13) Å. The trans-complex shows a reversible cyclic voltammogram for the Ni(2+/3+) couple and an axial ESR spectrum for the Ni(iii) species that is expected for such a symmetrical system. That there are no changes in the ESR spectroscopic features following redox cycles is consistent with the structural rigidity expected in an encapsulated system.

Synthesis and structure of a new macrotricyclic ligand that encapsulates lithium and transition metal ions

A new macrotricyclic ligand, L3 with an N4S2 donor set that encapsulates lithium and transition metal ions has been synthesized from the tetraazamacrocycle cyclam.

The synthesis, crystal structure, and spectroscopic characterization of a tetrakis(μ-N,N′-diarylformamidinato)chlorodirhenium(III,III) cationic complex

Abstract A variety of dirhenium compounds has been synthesized with (ArNC(H)NAr)− where Ar is a substituted C6H5 or C6H4 aryl ring with different electron withdrawing and electron donating substituents. Reactivity studies of AgBF4 with tetrakis(μ-N,N′-diarylformamidinato)dichlorodirhenium(III,III) complex with a p-MeO substituted aryl ring result in the loss of a single axial chloride from the Re2Cl2(III,III) species to yield a cationic complex, [Re2Cl[(p-MeOC6H4)NCHN(p-MeOC6H4)]4][BF4] and AgCl. The X-ray crystal structure, UV–Vis and NMR spectroscopy, and electrochemical characterization of the cationic Re2Cl(III,III) derivative [Re2Cl[(p-MeOC6H4)NCHN(p-MeOC6H4)]4][BF4] are compared to the parent neutral Re2Cl2(III,III) complex, Re2Cl2[(p-MeOC6H4)NCHN(p-MeOC6H4)]4.

1,1′,2,2′,3,3′-Tetrathiadiazafulvalenes; preparation and characterisation of trans-[ClCNS2CCS2NCCl]

Reduction of 4,5-dichloro-1,2,3-dithiazolylium chloride with two equivalents of triphenylantimony in liquid SO2 affords the 1,1′,2,2′,3,3′-tetrathiadiazafulvalene trans-[ClCNS2CCS2NCCl]; the structural features and redox chemistry of this novel ring system are described.

Preparation and structural characterization of naphtho[2,1-d:6,5-d′]bis([1,2,3]dithiazole) NT and π-stacked mixed valence salt [NT]3[BF4]2

Naphtho[2,1-d:6,5-d′]bis([1,2,3]dithiazole) NT, prepared by a ‘double Herz’ condensation of 2,6-diaminonaphthalene with S2Cl2, can be electrooxidized to the conductive, π-stacked mixed valence salt [NT]3[BF4]2.