Binuclear Triphenylantimony(V) Catecholates through N-Donor Linkers: Structural Features and Redox Properties.

A series of binuclear triphenylantimony(V) bis-catecholato complexes - of the type (Cat)PhSb-linker-SbPh(Cat) was prepared by a reaction of the corresponding mononuclear catecholates (Cat)SbPh with a neutral bidentate donor linker ligands pyrazine (Pyr), 4,4'-dipyridyl (Bipy), bis-(pyridine-4-yl)-disulfide (PySSPy), and diazobicyclo[2,2,2]octane (DABCO) in a dry toluene: Cat = 3,6-di-tert-butyl-catecholate (3,6-DBCat), linker = Pyr (); PySSPy (); Bipy (); DABCO (); Cat = 3,5-di-tert-butyl-catecholate (3,5-DBCat), linker = Bipy (); DABCO (); Cat = 4,5-(piperazine-1,4-diyl)-3,6-di-tert-butylcatecholate (pip-3,6-DBCat), linker = Bipy (); DABCO (); Cat = 4,5-dichloro-3,6-di-tert-butylcatecholate (4,5-Cl-3,6-DBCat), linker = Bipy (); DABCO (); and Cat = 4,5-dimethoxy-3,6-di-tert-butylcatecholate (4,5-(MeO)-3,6-DBCat), linker = Bipy (). The same reaction of (4,5-Cl-3,6-DBCat)SbPh with DABCO in an open atmosphere results in a formation of 1D coordination polymer {[(4,5-Cl-3,6-DBCat)SbPh·HO]·DABCO} (). Bis-catecholate complex PhSb(Cat-Spiro-Cat)SbPh reacts with Bipy as 1:1 yielding a rare macrocyclic tetranuclear compound {PhSb(Cat-Spiro-Cat)SbPh∙(Bipy)} ().

Low-coordinate Sm(II) and Yb(II) complexes derived from sterically-hindered 1,2-bis(imino)acenaphthene (Ar-bian).

Reduction of ArBIG-bian (1, 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene) with an excess of samarium in tetrahydrofuran (thf) and crystallization of the crude product from a thf/toluene mixture affords [(ArBIG-bian)Sm]·C7H8 (2a), which is free of the coordinating solvent. The use of 1,2-dimethoxyethane (dme) as the reaction medium resulted in the same product, [(ArBIG-bian)Sm]·C4H10O2 (2b), which differs from 2a only in the crystal lattice solvent. Reduction of 1 with an excess of ytterbium in dme gives compound [(ArBIG-bian)Yb(dme)]·2.

Novel dioxolene nickel complexes with sterically hindered diazabutadienes. Coupling of aza-ligands coordinated to nickel.

A square-planar bis-o-semiquinonato nickel complex interacts with N,N'-disubstituted 1,4-diazabutadienes-1,3 forming six-coordinate compounds. The X-ray structural study indicates complex geometry to be close to the octahedral. Magnetic properties are determined by metal-ligand ferromagnetic exchange interactions which are promoted by complex geometry.

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.

N,N'-fused bisphosphole: heteroaromatic molecule with two-coordinate and formally divalent phosphorus. Synthesis, electronic structure, and chemical properties.

The reduction of 6,12-dichloro-1,2,3,4,7,8,9,10-octahydro-6H,12H-[1,2,3]benzodiazaphospholo[2,1-a][1,2,3]benzodiazaphosphole (3) by metallic magnesium in tetrahydrofuran (THF) affords the N,N'-fused bisphosphole 1 in 92% yield. The compound reveals a novel type of 10π-electron heteroaromatic system [NICS(0) = -11.4], containing a two-coordinate and formally divalent phosphorus atom.

Boron complexes of redox-active diimine ligand.

Boron complexes (dpp-bian)BCl2 (1) and (dpp-bian)BX (X = Cl, 2; Br, 3) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) have been prepared by reacting mixtures dpp-bian-BX3 (1 : 1) with one (1) and two (2 and 3) equivalents of sodium correspondingly in toluene. Complexes 2 and 3 reveal a moderate stability against ambient oxygen and moisture. The reaction of complex 2 with PhC≡CLi gave compound (dpp-bian)B-C≡CPh (4).

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.

Dialane with a redox-active bis-amido ligand: unique reactivity towards alkynes.

The treatment of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with one equivalent of AlCl(3) and three equivalents of sodium in toluene at 110 °C produced a stable dialane, (dpp-bian)Al-Al(dpp-bian) (1). The reaction of compound 1 with pyridine gave Lewis-acid-base adduct (dpp-bian)(Py)Al-Al(Py)(dpp-bian) (2). Acetylene and phenylacetylene reacted with compound 1 to give cycloaddition products [dpp-bian(R(1)R(2))]Al-Al[(R(2)R(1))dpp-bian] (3: R(1)=R(2)=CH; 4: R(1)=CH, R(2)=CPh).

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.

Synthesis and molecular structure of indium complexes based on 3,6-di-tert-butyl-o-benzoquinone. Looking for indium(I) o-semiquinolate.

The interaction of 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) with indium in toluene leads to the tris-o-semiquinolate derivative (3,6-SQ)(3)In (3,6-SQ - radical-anion of 3,6-Q). According to single-crystal X-ray diffraction analysis, this complex has a trigonal prismatic structure. Magnetic measurements revealed that the exchange interactions between odd electrons of the paramagnetic ligands in (3,6-SQ)(3)In are antiferromagnetic in character.

The first structurally characterized metal (kappa(2)N,P)-phosphinohydrazides: the key to understanding the intramolecular rearrangement R2P-NR'-NR'-M --> R'N=PR2-NR'-M. Metalloderivatives of diisopropylphosphinohydrazines: synthesis and properties.

A number of novel phosphinohydrazines, iPr(2)P-NPh-NPh-H (1), iPr(2)P-NH-NH-PiPr(2) (2), iPr(2)P-NMe-NH-PiPr(2) (3), and H-NMe-NH-PiPr(2) (4), were prepared and characterized. The interaction of 1 with 1 equiv of n-BuLi afforded a complex compound [Li(DME)(3)][Li{(NPh-NPh-PiPr(2))-kappaN}(2)] (5). The reaction of 5 with NiBr(2) resulted in the formation of the first stable transition metal phosphinohydrazide [Ni{(NPh-NPh-PiPr(2))-kappa(2)N,P}(2)] (6).

Oxidation by oxygen and sulfur of Tin(IV) derivatives containing a redox-active o-amidophenolate ligand.

Oxidation of tin(IV) o-amidophenolate complexes [Sn(ap)Ph(2)] (1) and [Sn(ap)Et(2)(thf)] (2) (ap=dianion of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone (ImQ)) with molecular oxygen and sulfur in toluene solutions was investigated. The reaction of oxygen with 1 at room temperature forms a paramagnetic derivative [Sn(isq)(2)Ph(2)] (3) (isq=radical anion of ImQ) and diphenyltin(IV) oxide [{Ph(2)SnO}(n)]. Interaction of 1 with sulfur gives another monophenyl-substituted paramagnetic tin(IV) complex, [Sn(ap)(isq)Ph] (4), and the sulfide, [Ph(3)Sn](2)S.

Postmetallocene lanthanide-hydrido chemistry: A new family of complexes [{Ln{(Me3Si)2NC(NiPr)2}2(mu-H)}2] (Ln = Y, Nd, Sm, Gd, Yb) supported by guanidinate ligands-synthesis, structure, and catalytic activity in olefin polymerization.

The new family of Lewis base free hydrido complexes of rare-earth metals supported by guanidinate ligands [{Ln{(Me3Si)2NC(NiPr)2}2(mu-H)}2] (Ln = Y, Nd, Sm, Gd, Yb) was synthesized and structurally characterized. Single-crystal X-ray and solution NMR studies revealed that these complexes are dimeric in both solid state and in [D6]benzene. The dimeric hydrido complexes can adopt eclipsed (Nd, Sm, Gd) or staggered (Y, Yb, Lu) conformations depending on the metal-atom size.

Triphenylantimony(v) catecholates and o-amidophenolates: reversible binding of molecular oxygen.

Novel neutral antimony(V) complexes were isolated as crystalline materials and characterized by IR and NMR spectroscopy: o-amidophenolate complexes [4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolato]triphenylantimony(V) (Ph3Sb[AP-Me], 1) and [4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolato]triphenylantimony(v) (Ph3Sb[AP-iPr], 2); catecholate complexes (3,6-di-tert-butyl-4-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)Cat], 3), its methanol solvate 3CH3OH (4); (3,6-di-tert-butyl-4,5-di-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)2Cat], 5) and its acetonitrile solvate 5CH3CN (6). Complexes 1-7 were synthesized by oxidative addition of the corresponding o-iminobenzoquinones or o-benzoquinones to Ph3Sb. In the case of the phenanthrene-9,10-diolate (PhenCat) ligand, two different complexes were isolated: Ph3Sb[PhenCat] (7) and [Ph4Sb]+[Ph2Sb(PhenCat)2]- (8).

Bridging mu-eta(5):eta(4)-coordination of an indenyl ligand and reductive coupling of diazabutadienes in the assembly of di- and tetranuclear mixed-valent ytterbium indenyldiazabutadiene complexes.

The redox reaction of [Yb(C(9)H(7))(2)(thf)(2)] with the diazabutadiene PhN==C(Me)--C(Me)==NPh (DAD) has been found to depend on the molar ratio of the reactants. Reaction in a 1:2 molar ratio affords the dinuclear mixed-valent complex [Yb(2)(mu-eta(5):eta(4)-C(9)H(7))(eta(5)-C(9)H(7))(2){mu-eta(4):eta(4)-PhNC(Me)==C(Me)NPh}] containing an indenyl ligand with an unusual mu-eta(5):eta(4) bridging coordination. Reaction of equimolar amounts of these compounds results in an organolanthanide-mediated reductive coupling of the DAD ligands and formation of the tetranuclear mixed-valent complex [Yb(2)(mu-eta(5):eta(4)-C(9)H(7))(eta(5)-C(9)H(7))(2){mu-eta(4):eta(4)-PhNC(CH(2))==C(Me)NPh}](2) with a novel tetradentate tetraimine ligand.