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.

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.

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.

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.

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.

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.

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.

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.

Metal-to-ligand alkyl migration inducing carbon-sulfur bond cleavage in dialkyl yttrium complexes supported by thiazole-containing amidopyridinate ligands: synthesis, characterization, and catalytic activity in the intramolecular hydroamination reaction.

Neutral Y(III) dialkyl complexes supported by tridentate N(-) ,N,N monoanionic methylthiazole- or benzothiazole-amidopyridinate ligands have been prepared and completely characterized. Studies on their stability in solution revealed progressive rearrangement of the coordination sphere in the benzothiazole-containing system through an unprecedented metal-to-ligand alkyl migration and subsequent thiazole ring opening. Attempts to synthesize hydrido species from the dialkyl precursor led to the generation of a dimeric yttrium species stabilized by a trianionic N(-) ,N,N(-) ,S(-) ligand as the result of metal-to-ligand hydride migration with chemoselective thiazole ring opening and subsequent dimerization through intermolecular addition of the residual YH group to the imino fragment of a second equivalent of the ring-opened intermediate.

Reversible switching of coordination mode of ansa bis(amidinate) ligand in ytterbium complexes driven by oxidation state of the metal atom.

Reaction of bisamidine C6H4-1,2-{NC(t-Bu)NH(2,6-Me2C6H3)}2 (1) and [(Me3Si)2N]2Yb(THF)2 (THF = tetrahydrofuran) (toluene; room temperature) in a 1:1 molar ratio afforded a bis(amidinate) Yb(II) complex [C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]Yb(THF) (2) in 65% yield. Complex 2 features unusual κ(1)amide, η(6)-arene coordination of both amidinate fragments to the ytterbium ion, resulting in the formation of a bent bis(arene) structure. Oxidation of 2 by Ph3SnCl (1:1 molar ratio) or (PhCH2S)2 (1:0.

Divalent heteroleptic ytterbium complexes--effective catalysts for intermolecular styrene hydrophosphination and hydroamination.

New heteroleptic Yb(II)-amide species supported by amidinate and 1,3,6,8-tetra-tert-butylcarbazol-9-yl ligands [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]YbN(SiMe3)2(THF) (6) and [1,3,6,8-tBu4C12H4N]Yb[N(SiMe3)2](THF)n (n = 1 (7), 2 (8)) were synthesized using the amine elimination approach. Complex 6 features an unusual κ(1)-N,κ(2)-O,η(6)-arene coordination mode of the amidinate ligand onto Yb(II). Complexes 7 and 8 represent the first examples of lanthanide complexes with π-coordination of carbazol-9-yl ligands.

4,6-Di-tert-butyl-2,3-di-hydroxy-benzalde-hyde.

The title compound, C15H22O3, crystallizes with two independent mol-ecules in the asymmetric unit. In each mol-ecule, one hy-droxy group (at position 2) is involved in an intra-molecular O-H⋯O hydrogen bond, and another one (at position 3) exhibits bifurcated hydrogen-bonding being involved in intra- and inter-molecular O-H⋯O inter-actions. In the crystal, O-H⋯O hydrogen bonds link alternating independent mol-ecules into chains running along [010].

8-Quinolinolate complexes of yttrium and ytterbium: molecular arrangement and fragmentation under laser impact.

New 8-quinolinolate (Q) complexes of yttrium (1) and ytterbium (2) were synthesized by the reactions of Cp3Y and Yb[N(SiMe3)2]3 with 3 equiv. of 8-hydroxyquinoline in a DME solution. Single crystal X-ray analysis revealed the trinuclear molecular structure of the compounds Ln3Q9.

The new C-C bond formation in the reaction of o-amidophenolate indium(III) complex with alkyl iodides.

The reaction of bis(4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-amidophenolato)indium(III) anion with alkyl iodides is reported. This process includes oxidative addition of two RI (R = Me, Et) molecules to the non-transition metal complex and results in an alkyl transfer to ring carbon atoms with the formation of two new C-C bonds. The interaction proceeds at mild conditions and gives new indium(III) derivatives containing iminocyclohexa-1,4-dienolate type ligands.

Rare-earth dichloro and bis(alkyl) complexes supported by bulky amido-imino ligand. Synthesis, structure, reactivity and catalytic activity in isoprene polymerization.

A monoanionic amido-imino ligand system [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)](-) was successfully employed for the synthesis of monomeric dichloro [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]LnCl2(THF)2 (Ln = Y, 2Y; Lu, 2Lu) and bis(alkyl) [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Ln(CH2SiMe3)2(THF) (Ln = Y, 4Y; Lu, 4Lu) species of yttrium and lutetium. Dichloro complexes 2Y and 2Lu turned out to be unstable in aromatic solvents. The ligand symmetrization reaction in the case of 2Y affords the yttrium complex coordinated by dianionic [(2,6-iPr2C6H3)NC(=CH2)C(=CH2)N(C6H3-2,6-iPr2)](2-) ligand, (2,6-iPr2C6H3)N=C(Me)C(Me)=N(C6H3-2,6-iPr2) and YCl3.

Spin-labelled cyclometallated palladium complexes. EPR study of dynamic processes in coordination sphere.

New four-, five- and six-coordinated cyclometallated o-semiquinonato palladium complexes were obtained and characterized in solution by EPR. Interaction of square-planar azaphenyl palladium semiquinonate with mono and bidentate phosphane donors leads to formation of five- and six-coordinated adducts. Typical values of HFC constants on apical and basal phosphorouses are observed for such compounds.

Reversible binding of molecular oxygen to catecholate and amidophenolate complexes of SbV: electronic and steric factors.

Edge of reactivity: The reactions of reversible binding of molecular oxygen to catecholate and amidophenolate complexes of Sb(V) are investigated by analyzing the position of electronic (E(HOMO)) and steric (G-parameter) factors. The optimal electronic and steric parameters for such type reactions are found.

Sterically hindered o-quinone annulated with dithiete: a molecule comprising diolate and dithiolate coordination sites.

A new stable sterically hindered o-quinone annelated with a 1,2-dithiete ring was prepared by using mild conditions. The skeleton of the compound comprises diolate and dithiolate functions that have the potential to bind metals leading to the corresponding complexes. The reactivity of this compound as a ligand with respect to both coordination sites was studied.

A double addition of Ln-H to a carbon-carbon triple bond and competitive oxidation of ytterbium(II) and hydrido centers.

Addition of two Ln-H bonds of an Yb(II) hydrido complex supported by bulky amidinate ligand to a C≡C bond lead to the formation of 1,2-dianionic bibenzyl fragment. Both Yb(II) and hydrido centers are oxidized under the reaction conditions. The resulting Yb(II)-η(6) -arene interaction is surprisingly robust: the arene cannot be replaced from the metal coordination sphere when treated with Lewis bases.

Experimental and theoretical investigation of topological and energetic characteristics of Sb complexes reversibly binding molecular oxygen.

The experimental distribution of electron density in Ph(3)(4,5-OMe-3,6-Bu(t)-Cat)Sb·MeCN (1*) and Ph(3)(4,5-N(2)C(4)H(6)-3,6-Bu(t)-Cat)Sb·MeOH (2*) complexes was studied. According to atoms in molecules theory, the Sb-C(Ph), Sb-O(catecholate), and Sb···N(O) bonds are intermediate, whereas the O-C and C-C bonds are covalent, respectively. The energy of the Sb···N(MeCN) and Sb···O(MeOH) bonds are 7.

Steric control on the redox chemistry of (η5-C9H7)2Yb(II)(THF)2 by 6-aryl substituted iminopyridines.

A steric control on the reductive capacity of ytterbocenes towards iminopyridine ligands is described. The reaction of (η(5)-C(9)H(7))(2)Yb(THF)(2) with a series of 6-organyl-2-(aldimino)pyridyl ligands (IPy) takes place with the replacement of two THF molecules by one IPy unit. In contrast to the rich reductive ytterbocene chemistry described in the presence of the unsubstituted (aldimino)pyridyl ligand, all 6-aryl substituted IPys scrutinized hereafter are involved into the metal coordination as neutral bidentate {N,N} or tridentate {N,N,S; N,N,O} ligands, with no changes of the metal oxidation state in the final complexes.