Unexpected reactivity of an alkylaluminum complex of a non-innocent 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene ligand (dpp-bian).

The reaction of (dpp-bian)AlEt(EtO) (1) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with 4,4'-dimethoxybenzophenone leads to the replacement of EtO with the ketone resulting complex (dpp-bian)AlEt[O[double bond, length as m-dash]C(4-MeOCH)] (2). The reaction of compound 1 with 2,6-di-tert-butyl-4-methylphenol (1 : 1) or PhNH (1 : 1) affords the addition products [dpp-bian(H)]AlEt[O(2,6-tBu-4-MeCH)] (3) and [dpp-bian(H)]AlEt(NPh) (4) correspondingly. Treatment of complex 1 with 0.

Germylenes and stannylenes stabilized within N2PE rings (E = Ge or Sn): combined experimental and theoretical study.

The deprotonation of aminophosphanes PhP(NHR)2 (R = t-Bu or Dip; Dip = 2,6-i-Pr2C6H3) and t-BuP(NHDip)2 using n-BuLi gave, depending on the stoichiometry, both the dilithium compounds {[PhP(Nt-Bu)2]Li2}2 (), [PhP(Nt-Bu)(NDip)]Li2·(Et2O) (), [t-BuP(NDip)2]Li2·(Et2O)2 () and [t-BuP(NDip)2]Li2·(tmeda)2 (), and the monolithium compounds [PhP(NHt-Bu)(NR)]Li·(tmeda) (R = t-Bu , Dip ) and [t-BuP(NHDip)(NDip)]Li·(tmeda) (). Treatment of , and with GeCl2·dioxane or SnCl2 in a 1 : 1 stoichiometric ratio gave the corresponding tetrylenes [PhP(Nt-Bu)2]E (E = Ge , Sn ), [PhP(Nt-Bu)(NDip)]Ge () and [t-BuP(NDip)2]E (E = Ge , Sn ). The heteroleptic germylene [Ph(H)P(Nt-Bu)2]GeCl () was obtained by the reaction of the monolithium compound [PhP(NHt-Bu)(Nt-Bu)]Li·(tmeda) () with GeCl2·dioxane in a 1 : 1 stoichiometric ratio, as a result of a spontaneous NH → PH tautomeric shift in the ligand backbone.

Samarocene oxide: from an undesired decomposition product to a new reagent.

Samarocene oxide [Cp*2Sm-O-SmCp*2] is mostly considered as an undesired decomposition product of the well-established but highly air-sensitive samarocene, [Cp*2Sm(thf)2]. [Cp*2Sm-O-SmCp*2] is often formed by accidental exposure of [Cp*2Sm(thf)2] to air or wet solvents. We show here that [Cp*2Sm-O-SmCp*2] acts as a mild oxide base and thus is a valuable synthetic equivalent for "O(2-)".

Features of spectral properties of Sm(3+) complexes with dithia- and diselenophosphinate ligands.

The samarium complexes Sm(S2PPh2)3(THF)2 (1) and Sm(Se2PPh2)3(THF)2 (2) with soft-donor dithia- and diselenophosphinate ligands were synthesized and their photophysical properties were studied in detail. Both complexes displayed the metal-centered photoluminescence (PL) in visible and NIR regions corresponding to (4)G5/2→(6)HJ (J=5/2, 7/2, 9/2, 11/2, 13/2, 15/2), (6)FJ (J=1/2, 3/2, 5/2, 7/2, 9/2, 11/2) f-f transitions of Sm(3+). Luminescence decay curves exhibit an initial short build-up region and can be described by double or triple exponential function owing to multiphonon relaxation from the (4)F3/2 energy level to the (4)G5/2 one and reversible energy transfer from the Sm(3+) excited states to the triplet ((3)T1) state of phosphinate ligand.

New sterically-hindered o-quinones annelated with metal-dithiolates: regiospecificity in oxidative addition reactions of a bifacial ligand to the Pd and Pt complexes.

An unusual reactivity of sterically hindered o-quinones with an annelated dithiete ring towards coordination at a dithiolene site has been discovered. New Pd and Pt dithiolate complexes have been synthesized. The reaction proceeds regioselectively, and the quinone site of the parent ligand is not affected even while using an excess of the metal complex.

Tandem C(sp(2))-OMe Activation/C(sp(2))-C(sp(2)) Coupling in Early Transition-Metal Complexes: Aromatic C-O Activation beyond Late Transition Metals.

We report on combined structural, kinetic, and computational studies unraveling the mechanism of a unique, highly selective intramolecular C(sp(2))-OMe cleavage/C(sp(2))-C(sp(2)) coupling tandem reaction in group 3 metal (Y and Sc) complexes of amidine-amidopyridinate ligands. The latter process represents a rare stoichiometric model of the nonredox cleavage of inert C(sp(2))-O bonds relevant to cross-coupling reactions of aromatic ethers catalyzed by late transition metals.

Fine Substituent Effects in Sandwich Complexes: A Threshold Ionization Study of Monosubstituted Chromium Bisarene Compounds.

Mass-analyzed threshold ionization spectra of jet-cooled [(η(6) -PhMe)(η(6) -PhH)Cr] and [(η(6) -Ph2 )(η(6) -PhH)Cr] reveal with unprecedented accuracy the effects of methyl and phenyl groups on the electronic structure of bis(η(6) -benzene)chromium. These "pure" substituent effects allow quantitative experimental determination of the ionization energy changes caused by the mutual substituent influence in bisarene systems. Two types of such influence have been revealed for the first time in bis(η(6) -toluene)chromium.

Ln3I5(S2N2)(S2)(THF)10 - a new type of molecular compounds.

Unprecedented complexes of the composition Ln3I5(S2N2)(S2)(THF)10 were obtained in the reactions of neodymium and dysprosium iodide-nitrides with sulfur. The inorganic core of the molecules contains the cyclic fragments Ln(μ-S2)Ln, LnSNSN and LnSN. Ten of the fourteen atoms of the core are coplanar, the remaining four S2 and I2 atoms lie in the other two orthogonal planes.

Synthesis, structure and luminescent properties of lanthanide fluoroalkoxides.

Alkoxides [Ln(OR)3(DME)]2 (R = CH(CF3)2, Ln = Sm (1), Yb (2)), [Ce(OR)3(Phen)]2 (3) (Phen = 1,10-phenanthroline), [Ce(OR′)3(DME)2]2 (R′ = C(CF3)3) (4), {Gd(OR′)3(DME)2} (5), {Ln2[O(CF3)2C–C(CF3)2O]3} (Ln = Ce (6), Gd (7)), {Ce2[O(CF3)2C–C(CF3)2O]3(Phen)2} (8), and {Ce[O(CF3)2C–C(CF3)2O][O(CF3)2–C(CF3)2OH](Phen)2} (9) were synthesized by the reactions of silylamides Ln[N(SiMe3)2]3 with respective fluorinated alcohols. The heterovalent trinuclear complex {Sm2(μ2-OR)3(μ3-OR)2Sm(OR)2(THF)2.5(Et2O)0.

Cooperative reduction by Ln(2+) and Cp*(-) ions: synthesis and properties of Sm, Eu, and Yb complexes with 3,6-di-tert-butyl-o-benzoquinone.

The first examples of samarium, europium, and ytterbium complexes with 3,6-di-tert-butyl-o-benzoquinone(3,6-dbbq) in the form of catecholate have been obtained by reactions of the quinone with the corresponding lanthanocenes, [LnCp2*(thf)n] (n = 1 or 2) in solution. In the course of the reactions lanthanide ions lose one or two Cp* ligands, which take part in reduction of a quinone molecule into a catecholate anion (dbcat, 2(-)). As a result of the reactions, Sm and Yb clearly yield dimeric complexes[(LnCp*)2(dbcat)2], where each Ln ion loses one Cp* ligand.

Interaction of Azobenzene and Benzalaniline with Strong Amido Bases.

The interaction of azobenzene with lithium dicyclohexylamide (Cy2NLi) in THF or Et2O afforded the ion-radical salt of azobenzene (1) structurally characterized for the first time and dicyclohexylaminyl radical, which begins a novel chain of transformations leading eventually to the imino-enamido lithium complex (3). Benzalaniline, being a relative of azobenzene, reacted with Cy2NLi without electron transfer by a proton-abstraction mechanism to form the dilithium salt of N(1),N(2),1,2-tetraphenylethene-1,2-diamine quantitatively.

Addition of phenylacetylene to a magnesium complex of monoiminoacenaphtheneone (dpp-mian).

In the presence of formic acid, acenaphthenequinone (AQ) reacts with one molar equivalent of 2,6-diisopropylaniline in toluene to give monoiminoacenaphtheneone (3, dpp-mian) in good yield. Reduction of compound 3 with an excess of magnesium in thf results in green crystalline amido-alcoholate [(dpp-mian)Mg(thf)2]2 (4). Crystallization of complex 4 from toluene affords a blue tetramer [(dpp-mian)Mg(thf)]4 (5).

Nitroxide malonate methanofullerene as biomimetic model of interaction of nitroxide species with antioxidants.

Bis-nitroxide malonate methanofullerene (NO)2-MF was studied as a biomimetic model of reduction-oxidation activity with natural compounds-cytochrome c (cyt c), dihydroquercetin (DHQ), ascorbic acid (AA) and synthetic drug-1-(β-oxyethyl)-4,6-dimethyl-1,2-dihydro-2-oxopyrimidine (xymedon(®)). (NO)2-MF may be used as the component of Langmuir monolayers on an aqueous subphase and as the adsorbate on silica gel. The activity of (NO)2-MF in the reaction with cyt c was compared with the effect of nitroxide species such as gaseous nitric oxide, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) by using UV-vis and EPR-spectra.

Lattice-Modulated Phase Transition Coupled with Redox-Isomeric Interconversion of o-Semiquinone-Catecholato into Bis(o-semiquinonato) Cobalt Complexes.

Two redox-isomeric (valence tautomeric) complexes (2,2'-bpy)Co(3,6-DBSQ)2 (1) and (1,10-phen)Co(3,6-DBSQ)2 (2) (where 2,2'-bpy = 2,2'-dipyridine; 1,10-phen = 1,10-phenanthroline; 3,6-DBSQ = 3,6-di-tert-butyl-benzosemiquinone-1,2) reveal phase transitions that accompany redox-isomeric interconversions of semiquinone-catecholato isomer into a bis-(semiquinonato) one. Phase transitions differ one from another by thermodynamic parameters (transition temperature and interval, enthalpy, and entropy). Complexes 1 and 2 have the same crystal system and space group, and they form solid solutions with any molar ratio.

Heteroligand o-Semiquinonato-Formazanato Cobalt Complexes.

Two novel heteroligand o-semiquinonato-formazanato cobalt complexes [Co(3,6-SQ)(Form)] (1) and [Co(3,6-SQ)2(Form)] (2) (3,6-SQ is 3,6-di-tert-butyl-o-benzosemiquinonate radical anion; Form is 1,3,5-triphenylformazanate anion) were synthesized and characterized in detail. The molecular structures of [Co(3,6-SQ)(Form)] and [Co(3,6-SQ)2(Form)] were determined by X-ray analysis. Magnetic susceptibility measurements and spectroscopic studies have shown that square-planar complex 1 is diamagnetic with a residual paramagnetism due to antiferromagnetic exchange metal-ligand.

Indirect Magnetic Exchange between o-Iminosemiquinonate Ligands Controlled by Apical Substituent in Pentacoordinated Gallium(III) Complexes.

A number of pentacoordinated gallium complexes iSQ2GaR (1-7) (R = Et (1), Me (2), N3 (3), Cl (4), Br (5), I (6), NCS (7)) where iSQ is a radical anion of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone were synthesized, and crystalline samples of 1-7 were characterized using magnetic susceptibility measurements. The character of magnetic exchange interaction between spins of o-iminosemiquinonate radicals was found to be strongly influenced by the nature of the apical substituent. The antiferromagnetic coupling is predominant when the apical position is occupied by halogens or other tested inorganic anions, and the value of exchange interaction parameter varies from -99 to -176 K for R = I and NCS, respectively.

From Stiba- and Bismaheteroboroxines to N,C,N-Chelated Diorganoantimony(III) and Bismuth(III) Cations-An Unexpected Case of Aryl Group Migration.

An unprecedented transfer of an aryl group from boron to Sb and Bi is observed in the reaction of heteroboroxines of general formula ArM[(OBR)2O] [where M = Sb, Bi; Ar = C6H3-2,6-(CH2NMe2)2; R = Ph, 4-CF3C6H4, 4-BrC6H4] with corresponding boronic acid RB(OH)2. Using this procedure, ion pairs [ArMR](+)[R4B5O6](-) were obtained [where M = Sb and R = Ph (4), 4-CF3C6H4 (5), 4-BrC6H4 (6); where M = Bi and R = Ph (7), 4-CF3C6H4 (8), 4-BrC6H4 (9)]. All compounds were characterized using elemental analysis, electrospray ionization mass spectrometry, and multinuclear NMR spectroscopy, and molecular structures of 4 and 7 were determined by single-crystal X-ray diffraction analysis.

Luminescent properties of 2-mercaptobenzothiazolates of trivalent lanthanides.

A series of lanthanide complexes (Ln = Nd, Sm, Eu, Gd and Yb) with anionic 2-mercaptobenothiazolate (mbt) ligands were synthesized. Depending on the solvents chosen for the synthesis, Ln(mbt)3(THF)2 and Ln(mbt)3(Et2O) complexes were precipitated from THF and Et2O solutions respectively. The structure of Yb(mbt)3(Et2O) was determined by X-ray analysis.

Highly active, chemo- and regioselective Yb(II) and Sm(II) catalysts for the hydrophosphination of styrene with phenylphosphine.

Stable heteroleptic amido Yb(II) and Sm(II) complexes bearing aminoether-phenolate ligands and devoid of coordinated solvent have been structurally characterized. They afford highly active, chemoselective and, in the case of monoadditions, 100 % anti-Markovnikov regiospecific catalysts (down to 0.04 mol % loading) for the hydrophosphination of styrene with PhPH2 under mild conditions.

Metallacyclic yttrium alkyl and hydrido complexes: synthesis, structures and catalytic activity in intermolecular olefin hydrophosphination and hydroamination.

Metallacyclic neutral and ionic yttrium alkyl complexes coordinated by a dianionic ene-diamido ligand ([2,6-iPr2C6H3NC(Me)=C(Me)NC6H3iPr2-2,6] = L(1)) [L(1)]Y(CH2SiMe3)(THF)2 (2), {[L(1)]Y(CH2SiMe3)2}(-){Li(THF)4}(+) (3), [L(1)]Y(OEt2)(μ-Me)2Li(TMEDA) (4) were synthesized using a salt-metathesis approach starting from the related chloro complex [L(1)]Y(THF)2(μ-Cl)2Li(THF)2 (1) in 70, 85 and 72% yields respectively. The reactions of 2 with H2 or PhSiH3 afford the dimeric hydride {[L(1)]Y(THF)(μ-H)}2(μ-THF) (5) containing two μ-bridging hydrido and one μ-bridging THF ligands (91 and 85% yields). The X-ray studies of complexes 2, 3 and 5 revealed η(2)-coordination of the C=C fragment of an ene-diamido ligand to a Y cation.

Activation of SO2 with [(η(5) -C5 Me5 )2 Ln(THF)2 ] (Ln=Eu, Yb) leading to dithionite and sulfinate complexes.

The reaction of decamethylytterbocene [(η(5) -C5 Me5 )2 Yb(THF)2 ] with SO2 at low temperature gave two new compounds, namely, the Yb(III) dithionite/sulfinate complex [{(η(5) -C5 Me5 )2 Yb(μ3 ,1κ(2) O(1,3) ,2κ(3) O(2,2',4) -S2 O4 )}2 {(η(5) -C5 Me5 )Yb(μ,1κO,2κO'-C5 Me5 SO2 )}2 ] (1) and the Yb(III) dithionite complex [{(η(5) -C5 Me5 )2 Yb}2 (μ,1κ(2) O(1,3) ,2κ(2) O(2,4) -S2 O4 )] (2). After extraction of 1, the mixture was heated to give the dinuclear tetrasulfinate complex [{(η(5) -C5 Me5 )Yb}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 a). In contrast, from the reaction of [(η(5) -C5 Me5 )2 Eu(THF)2 ] with SO2 only the tetrasulfinate complex [{(η(5) -C5 Me5 )Eu}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 b) was isolated.

Adaptive behavior of a redox-active gallium carbenoid in complexes with molybdenum.

A gallium(I) carbenoid derived from redox-active diimine 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in complexes with molybdenum may serve either as a neutral [(dpp-bian)Ga:] or an anionic [(dpp-bian)Ga:](-) two-electron donor depending on the electronic state of the transition metal.

Electronic excited states of chromium and vanadium bisarene complexes revisited: interpretation of the absorption spectra on the basis of TD DFT calculations.

The nature and energies of the (arene)2Cr, (arene)2V and (arene)2Cr(+) (arene = η(6)-C6H6, η(6)-C6H5Me, η(6)-1,3-C6H4Me2, and η(6)-1,3,5-C6H3Me3) electronic excited states have been determined on the basis of the time-dependent density functional theory (TD DFT) approach and comparison with the gas-phase and condensed-phase absorption spectra. Both valence-shell and Rydberg electronic excitations were taken into account. The TD DFT results appear to describe correctly the influence of the metal atom and the ligand on the band positions and intensities in the UV-visible absorption spectra as well as the mixing of Rydberg and intravalency states.

Trinuclear alkyl hydrido rare-earth complexes supported by amidopyridinato ligands: synthesis, structures, C-Si bond activation and catalytic activity in ethylene polymerization.

The reaction of Ap(9Me)Lu(CH2SiMe3)2(thf) (Ap(9Me) = (2,4,6-trimethylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) with two molar equivalents of PhSiH3 affords a trinuclear alkyl-hydrido cluster [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]. The analogous reactions with Ap(9Me)Ln(CH2SiMe3)2(thf) (Ln = Y, Yb) are more complex and result in the formation of mixtures of two types of trinuclear alkyl-hydrido complexes [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiH2Ph)(thf)2] differing in the alkyl group. The DFT calculations of [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] (Ap* = (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) confirm localization of the HOMO on the Ap*-Y(1A)-CH2SiMe3 fragment, thus explaining its enhanced reactivity.

Digallane with redox-active diimine ligand: dualism of electron-transfer reactions.

The reactivity of digallane (dpp-Bian)Ga-Ga(dpp-Bian) (1), which consists of redox-active ligand 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-Bian), has been studied. The reaction of 1 with I2 proceeds via one-electron oxidation of each of two dpp-Bian ligands to a radical-anionic state and affords complex (dpp-Bian)IGa-GaI(dpp-Bian) (2). Dissolution of complex 2 in pyridine (Py) gives monomeric compound (dpp-Bian)GaI(Py) (3) as a result of a solvent-induced intramolecular electron transfer from the metal-metal bond to the dpp-Bian ligands.