Synthesis and electrochemistry of organometallic cobaltadithiaazulenes.

Reaction of tropolone or hinokitiol with phosphorus pentasulfide (P(2)S(5)) directly gives the sulfurized precursor [PS(2)(SST)](2) or [PS(2)(SSH)](2) (SST = dithiotropolonato or SSH = dithiohinokitiolato). The resulting [PS(2)(SST)](2) or [PS(2)(SSH)](2) is further reacted with [CpCoI(2)(CO)] (Cp = η(5)-cyclopentadienyl) to form the organometallic [CpCo(I)(SST)] (1) or [CpCo(I)(SSH)] (2), respectively. 1 and 2 have a cobaltadithiaazulene ring containing one cobalt and two sulfur atoms in the five-membered ring of azulene. Although X-ray structure analysis of 1 reveals the iodide-coordinated structure, 1 becomes the iodide-free complex [CpCo(SST)](+) (4(+)) in solution. Electrochemical studies of 4(+) by CV and spectroelectrochemical measurements (ESR, UV-vis-NIR) in solution are carried out. 4(+) is stepwise reduced by 2e(-) to form the stable neutral radical (4(•)) and unstable anion (4(-)). It is proposed that the anion 4(-) undergoes dimerization to afford the dimer (6(2-)) by anion radical coupling at the 5 or 7 position in the seven-membered ring of the cobaltadithiaazulene, since the similar anion radical coupling of a reduced azulene has been reported. Electrochemical reoxidation of 6(2-) slowly undergoes monomerization, giving the original monomer 4(•). DFT calculation of 4(+) explains that there is a delocalized lowest unoccupied molecular orbital (LUMO) in the whole molecule, and that of radical 4(•) has a delocalized singly occupied molecular orbital (SOMO). In these CpCo-SST (or SSH) complexes, there could be metal/ligand electron transfer since the SST (or SSH) ligand is potentially redox active. The spin density distribution of 4(-) obtained by the DFT method supports the mechanism of the anion radical coupling at the 5 or 7 position in the seven-membered ring.

Resuscitation of preterm infants with reduced oxygen results in less oxidative stress than resuscitation with 100% oxygen.

The objective of this study was to determine the effects of the level of inhaled oxygen during resuscitation on the levels of free radicals and anti-oxidative capacity in the heparinized venous blood of preterm infants. Forty four preterm infants <35 weeks of gestation with mild to moderate neonatal asphyxia were randomized into two groups. The first group of infants were resuscitated with 100% oxygen (100% O(2) group), while in the other group (reduced O(2) group), the oxygen concentration was titrated according to pulse oximeter readings. We measured total hydroperoxide (TH) and redox potential (RP) in the plasma within 60 min of birth. The integrated excessive oxygen ( summation operator(FiO(2)-0.21) x Time(min)) was higher in the 100% O(2) group than in the reduced O(2) group (p<0.0001). TH was higher in the 100% O(2) group than in the reduced O(2) group (p<0.0001). RP was not different between the 100% O(2) and reduced O(2) groups (p = 0.399). RP/TH ratio was lower in the 100% O(2) group than in the reduced O(2) group (p<0.01). We conclude that in the resuscitation of preterm infants with mild to moderate asphyxia, oxidative stress can be reduced by lowering the inspired oxygen concentration using a pulse oximeter.

Pachygyria in a girl with microcephalic osteodysplastic primordial short stature type II.

We report a mild form of lissencephaly or a pachygyric brain in a girl with microcephalic osteodysplastic primordial 'dwarfism' (MOPD) type II. She was born with severe intrauterine growth failure. A diagnosis of MOPD type II was warranted by persistent postnatal growth failure, microcephaly with a Seckel-like facial appearance, and distinctive radiological findings, including overtubulation of the long bones, metaphyseal cupping of the distal femora, and brachyphalangy with ivory epiphyses. Brain MRI showed thickened cerebral cortices with few and large gyri, most prominently in the frontal and posterior temporal regions. The Sylvian fissures developed incompletely, and the posterior horns of the lateral ventricle were dilated (colpocephaly). Despite the severe imaging findings, she showed only mild retardation of psychomotor development. To date, only minor brain malformations have attracted attention in MOPD type II. Our experience may suggest a wider spectrum of brain anomalies in this entity.

An organometallic dithiolene complex exhibiting electrochemically initiated hydrogen generation.

We clarify the electrochemical behavior of an organometallic cobalt dithiolene complex (1-NH) with a secondary sulfonyl amide (­NHSO(2)­) substituted Cp ligand involving proton dynamics. The reductions of 1-NH and its deprotonated derivative (1-N(−)) are centered on the CpCoS(2) moiety. The 2e(−) reduction of 1-NH quantitatively gives 1-N(−) with hydrogen generation.

Concurrent N-H and alpha-C-H bond activations of pyrrolidine and piperidine under ambient conditions by 18e tungsten allyl nitrosyl complexes.

18e Cp*W(NO)(CH2CMe3)(eta3-allyl) complexes effect concurrent N-H and alpha-C-H bond activations of cyclic, saturated amines under mild conditions, the conversions involving pyrrolidine being shown. In a similar manner, treatment of Cp*W(NO)(CH2CMe3)(eta3-3,3-Me2C3H3) with piperidine at room temperature results in the clean formation of the alkyl amido complex, Cp*W(NO)(CH2CMe3)(NC5H9CMe2CHCH2).

Electrochemical behavior of nickeladithiolene S,S'-dialkyl adducts: evidence for the formation of a metalladithiolene radical by electrochemical redox reactions.

The electrochemical behavior of nickeladithiolene S,S'-dialkyl adducts (alkyl = benzyl, methyl, tert-butyl) was investigated by using cyclic voltammetry (CV), visible, near-IR, and ESR spectroscopies and bulk electrolyses. The redox potentials of the S,S'-dialkyl adducts were influenced by the electron-donating effect of the functional group on the sulfur atoms. The nickeladithiolene S,S'-dibenzyl adduct [Ni[S(SCH(2)Ph)C(2)Ph(2)](2)] (2) eliminated one benzyl radical by one-electron reduction, and then the monobenzyl adduct anion [Ni(S(2)C(2)Ph(2))[S(2)(CH(2)Ph)C(2)Ph(2)]](-) (3(-)) was formed. Anion 3(-) was also formed by the reaction of nickeladithiolene dianion [Ni(S(2)C(2)Ph(2))(2)](2)(-) (1(2-)) with 1 equiv of benzyl cation. When anion 3(-) was oxidized, the long-lived nickeladithiolene radical [Ni(S(2)C(2)Ph(2))[S(2)(CH(2)Ph)C(2)Ph(2)]] (3) was formed. The visible, near-IR, and ESR spectra of radical 3 could be measured and assigned. When radical 3 was further oxidized, the oxidant 3(+) eliminated one benzyl cation, and then free nickeladithiolene (1) was generated.