The red, five-coordinate complexes Ru(CO)Cl(PPh(3))2(CH=CHPh) and [Ru(CO)Cl(PPh(3))2]2(mu-CH=CHC(6)H(4)CH=CH) undergo reversible coordination of PPh(3) at low temperature to produce the pale yellow, six-coordinate complexes Ru(CO)Cl(PPh(3))3(CH=CHPh) and [Ru(CO)Cl(PPh(3))3]2(mu-CH=CHC(6)H(4)CH=CH). X-ray crystal structures of the latter complex and of the hydride complex RuH(CO)Cl(PPh(3))3 were obtained. 1H and 31P NMR spectra between 20 and -70 degrees C exhibit large changes in both equilibrium constants and dynamic effects. Thermodynamic parameters, DeltaH = -17.5 +/- 2.0 kcal/mol and DeltaS = -57.5 +/- 7.6 eu, were obtained for PPh(3) coordination to the monoruthenium complex, and activation parameters, DeltaH = 20.6 +/- 0.7 kcal/mol and DeltaS = 41.6 +/- 2.0 eu, were obtained for the reverse decoordination. Coordination of PPh(3) was not observed upon cooling of the shorter bridged complex, [Ru(CO)Cl(PPh(3))2]2(mu-CH=CHCH=CH).

The butadienediyl-bridged complexes [(η 5 -C 5 R 5 )Fe(dppe)] 2 (µ-CHdCHCHdCH) (R ) H, Me) and their radical cationic and dicationic forms have been prepared and characterized by cyclic voltammetry, electronic spectroscopy (UV-vis and near-IR), EPR, and X-ray crystallography (R ) Me). Comparisons with each other and with the literature complexes [(η 5 -C 5 H 5 )Fe(dppm)] 2 (µ-CHdCHCHdCH), [(η 5 -C 5 Me 5 )Fe(dppe)] 2 (µ-CtCCtC), and [(η 5 -C 5 Me 5 )-Fe(dppe)] 2 (µ-C(OMe)dCHCHdC(OMe)) have allowed for systematic evaluation of several structural variations (C 5 H 5 vs C 5 Me 5 , dppm vs dppe, µ-CHdCHCHdCH vs µ-CtCCtC, and µ-CHdCHCHdCH vs µ-C(OMe)dCHCHdC(OMe)) and their effects on spectra and electronic intermetal coupling. Some of the structural changes have opposite effects on H ab , the effective coupling parameter, and K c , the comproportionation constant. The data for the mixed-valence cations are most consistent with electronic delocalization.Many recent examples of transition metals linked with conjugated bridges have shown that such bridges can promote electronic coupling between metal centers. 1 Studies of mixed-valence (MV) ions in comparison with fully oxidized and fully reduced states have provided much insight concerning delocalization and/or intramolecular electron transfer 2 and have allowed more accurate predictions concerning potential use as molecular wires. 3 Through systematic evaluation of trends related to isolated structural variations, the role of different structural aspects has sometimes been discerned. 4 For complexes linked by conjugated hydrocarbon bridges, such systematic studies are rare. 5 We have previously described the preparation of several butadienediyl-bridged diiron complexes, [CpFeLL′] 2 (µ-CHdCHCHdCH) (1-4, Cp ) η 5 -C 5 H 5 ; Scheme 1), and the oxidation of these neutral species to dicationic and MV radical cationic species. 6 Lapinte and co-workers have reported the closely related butadiynediyl-bridged complex [Cp*Fe(dppe)] 2 (µ-CtCCtC) (7, Cp* ) η 5 -C 5 Me 5 , dppe ) Ph 2 PCH 2 CH 2 PPh 2 ) 7 and the butadienediyl-bridged complex [Cp*Fe(dppe)] 2 -(µ-C(OMe)dCHCHdC(OMe)) ( 8), 8 each also prepared in three oxidation levels. Though the MV cation forms of all of these species were found to be delocalized, class III 9 complexes, several interesting differences were

Electronic communication between Fe centers in the diiron complexes [{(ηand −C 2 B 10 H 10 − was investigated by spectroscopic (UV−vis and IR), electrochemical (CV and DPV), and single-crystal XRD methods. All experimental results were supported by a DFT computational analysis (B3LYP/Def2SVP) of model complexes that included two other closo-boranes: X = −C 2 B 8 H 8 − and [−B 12 H 10 −] 2− . The DFT analysis focused on the geometry, electronic excitations, IR spectra, charge and spin delocalization, and intramolecular spin−spin exchange interactions in the series of all six complexes and their singly and doubly oxidized analogues. The results demonstrate that [closo-B 10 H 8 -1,10-diyl] 2− has the best ability among the closo-boranes to mediate electronic effects similar to those of 1,4phenylene. This is evident from the observed separation of one-electron-oxidation waves (∼70 mV) and comparable S−T energy gaps in the doubly oxidized species. Article pubs.acs.org/Organometallics

In this work, the liquid phase plasma reduction method was applied to prepare the spherical nickel nanoparticles from the solution of nickel chloride. A bipolar pulsed power supply was used to generate discharges in the aqueous solutions. Nickel nanoparticle peaks produced by surface plasmon absorption were observed around 381 nm with electrical discharge. Spherical nickel nanoparticles were mostly observed in this study, pentagonal nanoparticles were also observed occasionally. The TEM image showed that the average particle size varied from 10 to 200 nm in diameter as discharge time was increased. Many spots could be seen in the ED pattern for polycrystalline particles.

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