Monometallic derivatives of tetrakis(1,2,5-thiadiazole)porphyrazine, [TTDPzH2], with main group tervalent metal ions having the formulae [TTDPzMX] (TTDPz = tetrakis(1,2,5-thiadiazole)porphyrazinato dianion; M = Al(III), X = Cl-, Br-, OH-; M = Ga(III), X = Cl-, OH-; M = In(III), X = AcO-) were prepared and investigated by single-crystal X-ray analysis and IR and UV-vis spectroscopy as well as cyclic voltammetry and spectroelectrochemistry. The complexes [TTDPzMX] (M = Al(III), X = Cl-, Br-; M = Ga(III), X = Cl-) were obtained by direct autocyclotetramerization of the precursor 3,4-dicyano-1,2,5-thiadiazole in hot quinoline in the presence of MX3 salts (M = Al(III), Ga(III); X = Cl-, Br-) and were hydrolized to form the corresponding hydroxide derivatives, [TTDPzMOH]. The In(III) complex, [TTDPzIn(OAc)], was obtained from the free-base macrocycle [TTDPzH2] with In(OH)(OAc)2 in CH3COOH. A single-crystal X-ray study was made at 173 K on the two isostructural species [TTDPzMCl] (M = Al(III), Ga(III)), which have space group P, with a = 12.470(14), b = 12.464(13), and c = 13.947(12) angstroms, alpha = 70.72(3), beta = 79.76(3), and gamma = 90.06(3) degrees, V = 2009.3(3) angstroms3, and Z = 4 for [TTDPzAlCl] and a = 12.429(3), b = 12.430(3), and c = 13.851(3) angstroms, alpha = 70.663(6), beta = 79.788(8), and gamma = 89.991(9) degrees, V = 1983.3(7) angstroms3, and Z = 4 for [TTDPzGaCl]. Square pyramidal coordination exists about the M(III) centers, with Cl- occupying the apical position (Al-Cl = 2.171(5) and Ga-Cl = 2.193(1) angstroms). Al(III) and Ga(III) are located at distances of 0.416(6) and 0.444(2) angstroms from the center of the N4 system. The molecular packing consists of stacked double layers with internal and external average interlayer distances of 3.2 and 3.3 angstroms, respectively. IR spectra show nu(Al-Cl) at 345 cm(-1) for [TTDPzAlCl], nu(Al-Br) at 330 cm(-1) for [TTDPzAlBr], and nu(Ga-Cl) at 382 cm(-1) for [TTDPzGaCl]. The UV-vis spectra in weakly basic (pyridine, DMF, DMSO) and acidic solvents (CF3COOH, H2SO4) show the typical intense pi --> pi transition bands in the Soret (300-400 nm) and Q-band regions (640-660 nm), the bands evidencing some dependence on the nature of the solvent, particularly in acidic solutions. Cyclic voltammetry, differential pulse voltammetry, and thin-layer spectroelectrochemical measurements in pyridine and dimethylformamide of the species [TTDPzMX] indicate reversible first and second one-electron reductions, whereas additional ill-defined reductions are observed at more negative potentials. The examined species are much easier to reduce than their phthalocyanine or porphyrin analogues as a result of the remarkable electron-attracting properties of the TTDPz macrocycle which contains annulated strongly electron-deficient thiadiazole rings.

The laccase from Steccherinum murashkinskyi is a member of the large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates, accompanied by the reduction of dioxygen to water. The reducing properties of X-ray radiation and the high quality of the laccase crystals allow the study of the catalytic reduction of dioxygen to water directly in a crystal. A series of diffraction data sets with increasing absorbed radiation dose were collected from a single crystal of Steccherinum murashkinskyi laccase at 1.35 Å resolution. Changes in the active-site structure associated with the reduction of molecular oxygen to water on increasing the absorbed dose of ionizing radiation were detected. The structures in the series are mixtures of different states of the enzyme-substrate complex. Nevertheless, it was possible to interpret these structures as complexes of various oxygen ligands with copper ions in different oxidation states. The results allowed the mechanism of oxygen reduction catalyzed by laccases to be refined.

Tetrapyrazinocorrolazines -first corrolazine derivatives with annulated heterocycleshave been prepared as phosphorus(V) complexes by the reaction of metal free tetrapyrazinoporphyrazines [(R 8 TPyzPA)H 2 ] (R = Ph, Me) with phosphorus(III) chloride or bromide in pyridine. Oxophosphorus(V) complexes [(R 8 TPyzCA)P=O] were obtained when the reaction mixture was poured into water, while dilution with methanol leads to dimethoxyphosphorus(V) complexes [(R 8 TPyzCA)P(OMe) 2 ]. The obtained compounds were characterized by MALDI-TOF mass-spectrometry and by IR, 1 H, 31 P NMR measurements. Their UV-vis spectral and basic properties in CH 2 Cl 2 -CF 3 COOH medium were studied in comparison to phosphorus(V) complex of octaphenylcorrolazine [(Ph 8 CA)P=O].Fig. 8. UV-vis spectral changes observed for P V octaphenyltetrapyrazinocorrolazine in CH 2 Cl 2 (a) upon addition of CF 3 COOH (0.04 → 0.16 → 1.3 M, b→c→d); in 100% CF 3 COOH (e) and in 96% H 2 SO 4 (f ) J. Porphyrins Phthalocyanines Downloaded from www.worldscientific.com by MASSACHUSETS INSTITUTE OF TECHNOLOGY on 11/26/14. For personal use only.

The chloroiron(III) complex of 2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,10-diazaporphyrin, [(Cl)FeMBDAP], was prepared and studied by X-ray crystallography and by solution (1)H NMR and UV-vis measurements. In the crystal structure of hemisolvate [(Cl)FeMBDAP] x 0.5CHCl(3), two nonequivalent [(Cl)FeMBDAP] units containing Fe1 and Fe2 are arranged in pi-dimers with considerable overlap on their concave sides. Axial chloride bonded to Fe2 is solvated by hydrogen bonding with CHCl(3). Parameters of the coordination pyramid have typical values for the spin-mixed (S = 3/2 / 5/2) Fe(III) complexes in the case of Fe1 and are characteristic for the pure intermediate-spin state for Fe2 (displacement from the (N(Pyr))(4) planes - 0.385 and 0.290 A and the average N(Pyr)-Fe bond lengths -1.992 and 1.954 A for Fe1 and Fe2, respectively). Effective magnetic moments in CHCl(3) and CH(2)Cl(2) capable of specific solvation of chloride by hydrogen bonding (4.5-4.6 micro(B) at 298 K) are indicative about mixed intermediate/high-spin state S = 3/2 / 5/2, with the S = 3/2 contribution increasing upon lowering of the temperature (4.02 micro(B) in CD(2)Cl(2) at 193 K). In nonsolvating CCl(4), C(6)D(6), and THF-d(8), the mu(eff) values are consistent with the predominantly high-spin state at ambient temperature (5.5-5.75 micro(B) at 298 K) and almost pure S = 5/2 state at low temperature (ca. 5.9 micro(B) in THF-d(8) below 270 K). Downfield isotropic shifts from 35 to 50 ppm are observed for alpha-alkyl protons and upfield shifts from -5 to -15 ppm for meso-CH protons, which is characteristic for the presence of the intermediate-spin state. The splitting of signals of the diastereotopic alpha-CH(2) protons is increased with growth of the S = 3/2 state contribution from 1.5 to 4 ppm in nonsolvating to 11 ppm in specifically solvating solvents at 298 K and further to 31 ppm at 193 K (in CD(2)Cl(2)). In the presence of DMSO addition and in methanol solution, the single CH(2) signal is observed at 25-28 ppm, and the meso-CH resonance is also shifted downfield to ca. 30 ppm, indicating the formation of six-coordinated complexes [(DMSO)(2)FeMBDAP](+) and [(MeOH)(2)FeMBDAP](+), the latter having the mu(eff) value of 4.92 micro(B) at 291 K is a spin-mixed species. The electron spin resonance spectra recorded at 77 K indicates that in frozen glasses in CD(2)Cl(2) and THF molecules in the high-spin state (g( perpendicular) approximately 6) and the predominantly intermediate-spin state (g( perpendicular) approximately 4.2-4.3) coexist together.