Dalton Transactions

doi: 10.1039/b612682kpmid: N/A

doi: 10.1039/b612685ppmid: N/A

doi: 10.1039/b612686npmid: N/A

Hagen, Wilfred R.

doi: 10.1039/b608163kpmid: 16981015

Molecular paramagnetism pervades the bioinorganic chemistry of V, Mn, Fe, Co, Ni, Cu, Mo, W, and of a number of non-biological transition elements. To date we can look back at half a century of fruitful EPR studies on metalloproteins, and against this background evaluate the significance of modern EPR spectroscopy from the perspective of a biochemist, making a distinction between conventional continuous wave X-band spectroscopy as a reliable work horse with broad, established applicability even on crude preparations, . a diffuse set of “advanced EPR” technologies whose practical application typically calls for narrowly focused research hypotheses and very high quality samples. The type of knowledge on metalloproteins that is readily obtainable with EPR spectroscopy, is explained with illustrative examples, as is the relation between experimental complexity and the spin value of the system.

Langer, Robert; Shi, Weifeng; Rothenberger, Alexander

doi: 10.1039/b610228jpmid: 16981016

The synthesis of [(PhAs)(µ-S)(µ-S)] and its reactions to form novel Cu() complexes are reported, together with a new cleavage reaction of disulfides by Cu() thiolates and tertiary phosphines.

Morishita, Yasuhiko; Kogane, Tamizo; Nogami, Takashi; Ishida, Takayuki

doi: 10.1039/b609128hpmid: 16981017

Tetranuclear copper() complexes were obtained after simply dissolving [Cu(hfac)] in formamide–methanol mixed solvents (Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione). X-Ray diffraction studies revealed that they possessed a tetranuclear double half-cubane core sandwiched with two trianionic ligands from 2,4,6-tris(trifluoromethyl)tetrahydropyran-2,4,6-triol (Httpt). Complexes [Cu(ttpt)(hfac)(dmf)], [Cu(ttpt)(tfa)(def)], and [Cu(ttpt)(hfac)(HO)](fa) were prepared from ,-dimethylformamide(dmf)–MeOH, ,-diethylformamide (def)–MeOH, and formamide(fa)–MeOH (Htfa = trifluoroacetic acid), respectively. A possible mechanism is proposed where a templated aldol-type reaction takes place between hfac and 1,1,1-trifluoroacetonate. Magnetic measurements revealed the presence of antiferromagnetic interaction in the CuO core.

Saito, Ken; Arai, Takashi; Takahashi, Naoki; Tsukuda, Toshiaki; Tsubomura, Taro

doi: 10.1039/b608641apmid: 16981018

A series of Cu() mixed-ligand complexes containing dmp (2,9-dimethyl-1,10-phenanthroline) and one of simple diphosphine ligands (PhP(CH)PPh) were prepared. Among the complexes, [Cu(dppp)(dmp)]PF ( = 3) and [Cu(dppb)(dmp)](PF) ( = 4) were characterized by X-ray structure analyses. The dppp complex has been characterized as a mononuclear complex, while [Cu(dppb)(dmp)] exists as a dinuclear complex in which two dppb ligands bridge between the two Cu() atoms. Although the distorted tetrahedral structures around the central metals of the two complexes are similar, the P–Cu–P angles are different between the two complexes. All of the series of complexes show photoluminescence in solution, and the intensity of the luminescence increases with ( = 2–4). The non-radiative rate constants of the complexes decrease markedly with although radiative rate constants of the complexes are similar.

Cheng, Yanxiang; Doyle, David J.; Hitchcock, Peter B.; Lappert, Michael F.

doi: 10.1039/b607782jpmid: 16981019

The synthesis of the following crystalline complexes is described: [Li(L)(thf)] (), [Li(L)(tmeda)] (), [MCl(L)] [M = Al (), Ga ()], [In(Cl)(L)(µ-Cl)Li(OEt)] (), [In(Cl)(L){N(H)CHPr-2,6}] (), [In(L){N(H)CHPr-2,6}] (), [{In(Cl)(L)(µ-OH)}] (), [L(Cl)In–In(Cl)(L)] () (the thf-solvate , the solvate-free and the hexane-solvate ), [{In(Cl)L}(µ-S)] () and [InCl(L)(tmeda)] () ([L] = [{N(CHPr-2,6)C(H)}CPh]). From H(L) (), Li(L) in EtO, and thf, tmeda, AlCl, GaCl or InCl there was obtained , , , or , respectively in excellent yield. Compound was the precursor for each of , and [{InCl(tmeda){µ-(OSnMe)}}] () by treatment with one () or two () equivalents of K[N(H)(CHPr-2,6)], successively Li[N(SiMe)(CHPr-2,6)] and moist air (), Na in thf (), tmeda (), or successively tmeda and MeSnSnMe (). Crystals of (with an equivalent of In) and were obtained from InCl or thermolysis of [In(Cl)(L){N(SiMe)(CHPr-2,6)}] () {prepared from and Li[N(SiMe)(CHPr-2,6)] in EtO}, respectively. Compound was obtained from a thf solution of and sulfur. X-Ray data for crystalline , , , , , and are presented. The M(L) moiety in each (not the L-free ) has the monoanionic L ligated to the metal in the N,N′-chelating mode. The MN1C1C2C3N2 six-membered M(L) ring is π-delocalised and has the half-chair (, and ) or boat (, and ) conformation.

Vinyard, David J.; Richter, Mark M.

doi: 10.1039/b608145bpmid: 16981020

The spectroscopy, electrochemistry, and electrogenerated chemiluminescence (ECL) of [(q)(qH)Li] (qH = 8-hydroxyquinolinato) and [(Meq)(MeqH)Li] (MeQH = 2-methyl-8-hydroxyquinolinato) have been investigated. In both acetonitrile and aqueous solutions, [(q)(qH)Li] and [(Meq)(MeqH)Li] have absorption maxima at 320 and 309 nm, respectively. When excited at these wavelengths, the complexes emit around 500 nm (blue–green) in acetonitrile. Photoluminescence efficiencies () were 0.036 for [(q)(qH)Li] and 0.012 for [(Meq)(MeqH)Li] when compared to Ru(bpy) (bpy = 2,2′-bipyridine) with = 0.042. No photoluminescence was observed in aqueous media. The complexes show irreversible oxidative electrochemistry and quasi-reversible reductions in acetonitrile. ECL efficiencies () were 0.097 for [(q)(qH)Li] and 0.080 for [(Meq)(MeqH)Li] when compared to Ru(bpy) ( = 1) in aqueous buffered solution and 0.035 for [(q)(qH)Li] and 0.028 for [(Meq)(MeqH)Li] in acetonitrile (0.05 M tri--propylamine (TPrA) as an oxidative–reductive ECL co-reactant). The ECL peaks at a potential corresponding to oxidation of both the TPrA and [(q)(qH)Li] or [(Meq)(MeqH)Li]. Also, qualitative studies using transmission filters suggest that both complexes emit ECL in approximately the same blue–green region as their photoluminescence, indicating that the same excited state is formed in both experiments.

Natrajan, Louise S.; Blake, Alexander J.; Wilson, Claire; Weinstein, Julia A.; Arnold, Polly L.

doi: 10.1039/b602242apmid: 16981021

Metathesis of lanthanide tris di--butyl β-diketonates ([Ln(thd)] Ln = Pr, Nd, Eu, Tb) with one or two equivalents of group 1 salts of the sulfur bridged binaphtholate dianion [1,1′-S(2-OCHBu-3,6)], [ML], M = K, Li affords luminescent mono- and bis-ligand substituted complexes ML[LnL(thd)].L; M = K, Ln = Pr , Nd , Eu and Tb (L = thf, diethyl ether or toluene) and M(thf)[LnL(thd)]; M = Li, Ln = Pr , Nd , Eu , Tb . The potassium salt [KL] affords mono-L substituted complexes most cleanly, while the lithium salt [LiL] yields the bis-L substituted complexes most cleanly. The L ligands function as antenna for the sensitised lanthanide-centred emission in Eu and Tb complexes. The X-ray single-crystal structures of mono- and bis-L lanthanide complexes of Nd are presented.