Protonation of magnesium and sodium complexes containing dianionic diimine ligands. Molecular structures of 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene (dpp-BIAN), [(dph-BIAN)H<Subscript>2</Subscript>(Et<Subscript>2</Subscript>O)], and [(dpp-BIAN)HNa(Et<Subscript>2</Subscript>O)]

Hydrolysis of magnesium complexes containing the dianionic acenaphthenediimine ligands, (dpp-BIAN)Mg(thf)₃ (1), (dph-BIAN)Mg(thf)₃ (2), and (dtb-BIAN)Mg(thf)₂ (3) (dpp-BIAN is 1,2-bis{ (2,6-diisopropylphenyl)imino}acenaphthene; dph-BIAN is 1,2-bis{(2-diphenyl)imino}acenaphthene; dtb-BIAN is 1,2-bis{(2,5-di-tert-butylphenyl)imino}acenaphthene), affords the corresponding diamines (dpp-BIAN)H₂ (4), (dph-BIAN)H₂(Et₂O) (5), and (dtb-BIAN)H₂ (6). Compounds 4 and 5 were isolated in the crystalline state and characterized by UV-Vis, IR, and ¹H NMR spectroscopy. Partial hydrolysis of (dpp-BIAN)Na₂(Et₂O)₃ gave the crystalline (dpp-BIAN)HNa(Et₂O)₂ complex (7), which was also characterized by spectroscopic methods. The structures of compounds 5 and 7 and free diimine dpp-BIAN were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2634–2640, December, 2004.     

Magnesium and calcium complexes with two diimine radical-anion ligands. Molecular structure of the Ca complex with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Four- and five-coordinate magnesium and calcium complexes containing two diimine radical-anion ligands with compositions (dpp-BIAN)₂Mg (1), (dpp-BIAN)₂Ca (2), (dtb-BIAN)₂Mg (3), and (dtb-BIAN)₂Ca(THF) (4) (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene and dtb-BIAN is 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were synthesized. At 120 K, the ESR spectra of complexes 1–4 in a toluene matrix show signals characteristic of biradical derivatives. The molecular structure of compound 2 was established by X-ray diffraction analysis. At 293 K, the magnetic moments of compounds 1, 2, 3, and 4 are 2.55, 2.57, 2.76, and 2.79 μ_B, respectively, which are indicative of the presence of two unpaired electrons localized on the ligands.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2051–2055, October, 2004.     

Reduction of aromatic ketones with the (dpp-BIAN)AlI(Et2O) complex

Reduction of benzophenone and 4,4′-bis(methoxy)benzophenone with the aluminum complex (dpp-BIAN)AlI(Et₂O) (1) containing the dianionic dpp-BIAN ligand (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) affords the pinacolate complexes [(dpp-BIAN)AlI]₂[μ-O₂C₂Ph₄] (2) and [(dpp-BIAN)AlI]₂[μ-O₂C₂(C₆H₄OMe)₄] (3), respectively, which undergo the pinacolone rearrangement upon prolonged storage in diethyl ether to form [(dpp-BIAN)AlI]₂O (4). The reaction of 1 with fluoren-9-one produces stable pinacolate (dpp-BIAN)Al[μ-O₂(C₁₃H₈)₂] (7) and the (dpp-BIAN)AlI₂ complex (8). Compounds 2—4, 7, and 8 were characterized by ESR spectroscopy. Hydrolysis products of compounds 2 and 3 were characterized by ¹H NMR spectroscopy. The structures of complexes 4 and 7 were established by X-ray diffraction. dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1134–1140, July, 2006.     

Coordination of benzene to a sodium cation

The complexes Na(Et₂O)(dpp-BIAN)AlEt₂ (5) and Na(η⁶-C₆H₆)(dpp-BIAN)AlEt₂ (6) were synthesized by reactions of the disodium salts of dpp-BIAN (dpp-BIAN is 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene) with 1 equiv. of Et₂AlCl in diethyl ether and benzene, respectively. The structures of both complexes were established by X-ray diffraction. In molecules 5 and 6, diethylaluminum is chelated by the dianionic dpp-BIAN ligand. The sodium cations in molecules 5 and 6 are located above the plane of the diimine fragments and coordinate the Et₂O or benzene molecule, respectively. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1702–1707, September, 2007.     

Synthesis and structure of novel chiral amido-imine complexes of aluminum,gallium, and indium

The reactions of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN, 1) with tri-iso-butylaluminum, triethylgallium or trimethylindium give the novel amido-imine complexes (Buⁱ—dpp-BIAN)AlBuⁱ ₂ (4), (Et—dpp-BIAN)GaEt₂ (5), and (Me—dpp-BIAN)InMe₂ (6), respectively. The reaction of (dpp-BIAN)AlI(Et₂O) (7) with allyl bromide affords analogous chiral amido-imine derivative (All—dpp-BIAN)AlBrI (8). Hydrolysis of 8 affords the amino-imino compound (All—dpp-BIAN)H (9). The new compounds 4–6, 8, and 9 have been characterized by ¹H NMR and IR spectroscopy. The molecular structures of 5, 6, and 9 were determined by single crystal X-ray analysis.     

Reactions of (dpp-BIAN)Mg(thf)<Subscript>3</Subscript> complex (dpp-BIAN is 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene) with halogen-containing reagents

The reactions of the acenaphthenediimine complex (dpp-BIAN)Mg(thf)₃ (1) (dpp-BIAN is 1,2-bis{ (2,6-diisopropylphenyl)imino}acenaphthene) with various chlorine-, bromine-, and iodine-containing reagents afforded the unsymmetrical compounds [(dpp-BIAN)MgCl(thf)]₂ (6), [(dpp-BIAN)MgBr(thf)]₂ (7), and (dpp-BIAN)MgI(DME) (8). The reaction of complex 1 with Me₃SiCl in THF is accompanied by the cleavage of the THF molecule to form [{dpp-BIAN(CH₂)₄OSiMe₃}MgCl]₂ (9), in which the trimethylsilanyloxybutyl group is bound to one of the carbon atoms of the diimine fragment. The reaction of complex 1 with Me₂NCH₂CH₂Cl in THF produces the [dpp-BIAN(H)(CH₂)₂NMe₂] compound (10) containing no magnesium. Paramagnetic complexes 6–8 were characterized by ESR spectroscopy. Diamagnetic compounds 9 and 10 were studied by ¹H and ¹³C NMR spectroscopy. The molecular structures of complexes 6–10 were established by X-ray diffraction analysis. In the crystalline state, compounds 6, 7, and 9 exist as halogen-bridged dimers. In all magnesium derivatives, BIAN serves as a chelate ligand.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2641–2651, December, 2004.     

Aluminum complexes with mono-and dianionic diimine ligands

The metathesis reaction of the magnesium complex [(dpp-BIAN)²⁻Mg²⁺(THF)₃] (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with one equivalent of AlCl₃ in toluene gave the [(dpp-BIAN)²⁻AlCl₂]⁻[Mg₂Cl₃(THF)₆]⁺ complex (1). Reduction of dpp-BIAN with aluminum metal in the presence of AlCl₃ and AlI₃ in toluene and diethyl ether afforded the radical-anionic complex [(dpp-BIAN)⁻AlCl²] (2) and the dianionic complexes [(dpp-BIAN)²⁻AlI(Et₂O)] (3) and [(dpp-BIAN)²⁻AlCl(Et₂O)] (4), respectively. Compounds 1–4 were isolated in the crystalline state and characterized by IR spectroscopy and elemental analysis. The structures of compounds 1–3 were established by X-ray diffraction. Compound 2 was characterized by ESR spectroscopy. Compounds 3 and 4 were studied by 1H and 13C NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 409–415, March, 2006.     

Generation of a Hetero Spin Complex from Iron(II) Iodide with Redox Active Acenaphthene-1,2-Diimine

The reaction of the redox active 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) and iron(II) iodide in acetonitrile led to a new complex [(dpp-BIAN)Fe^III₂] (1). Molecular structure of 1 was determined by the single crystal X-ray diffraction analysis. The spin state of the iron cation in complex 1 at room temperature and the magnetic behavior of 1 in the temperature range of 2–300 K were studied using Mossbauer spectroscopy and magnetic susceptibility measurements, respectively. The neutral character of dpp-BIAN in 1 was confirmed by IR and UV spectroscopy. The electrochemistry of 1 was studied in solution and solid state using cyclic voltammetry. The generation of the radical anion form of the dpp-BIAN ligand upon reduction of 1 in a CH₂Cl₂ solution was monitored by EPR spectroscopy.     

Anionic and neutral bis(diimine)lanthanide complexes

Oxidation of ytterbium(II) complex (dpp-BIAN)Yb(DME)₂ (1) with dpp-BIAN affords an ionic compound [(dpp-BIAN)₂Yb]^?[(dpp-BIAN)Yb(DME)₂]⁺ (2) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene), in which the oxidation states of the metals in anionic and cationic counterparts are different. Structurally related lanthanum(III) complex [(dpp-BIAN)₂La]^?[(dpp-BIAN)La(DME)₂]⁺ (3) has been prepared reacting excess of metallic lanthanum with dpp-BIAN. Compound [(dpp-BIAN)₂La]^?[K(Et₂O)₄]⁺ (4) has been isolated from the reaction of LaI₃ with three molar equivalents of potassium and one molar equivalent of dpp-BIAN in diethyl ether. The reaction of SmI₂ with dpp-BIAN and potassium affords complex [(dpp-BIAN)₂Sm]^?[K(C₆H₆)]⁺ (5). Treatment of compound 5 with 0.5 molar equivalent of iodine produces neutral complex (dpp-BIAN)₂Sm (6). Molecular structures of complexes 2–6 have been determined by X-ray crystallography.     

New high-spin iron complexes based on bis(imino)acenaphthenes (BIAN): synthesis,structure, and magnetic properties

The reactions of iron diiodide with one and two equivalents of the monopotassium salt of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) in diethyl ether gave the complexes [(dpp-BIAN)FeI]₂ (1) and (dpp-BIAN)₂Fe (2), respectively. The bis-ligand complex (tms-BIAN)₂Fe (3) was synthesized by the exchange reaction of the monosodium salt of 1,2-bis(trimethylsilylimino)acenaphthene (tms-BIAN) with iron diiodide. The reaction of FeI₂ with tms-BIAN affords the chelate complex (tms-BIAN)FeI₂ (4), whereas the reaction of FeBr₂·2H₂O with tms-BIAN is accompanied by elimination of trimethylsilyl groups to form the tris-ligand acenaphthene-1,2-diimine complex [(H₂BIAN)₃Fe][FeBr₃·THF]₂ (5) containing two types of iron ions. Compounds 1–5 were characterized by IR spectroscopy and elemental analysis. The molecular structures of 1–5 were determined by single-crystal X-ray diffraction. For high-spin complexes 1–3, the temperature-dependent magnetic susceptibilities were measured in the range of 4–300 K.     

Synthesis and guest exchange reactions of inclusion compounds of cucurbit[8]uril with nickel(II) and copper(II) complexes

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex, {trans-[Ni(en)₂(H₂O)₂]@CB[8]}Cl₂ · 23.5H₂O, the copper(II) complex, {2[Cu(dien)(bipy)(H₂O)]@CB[8]}(ClO₄)₄ · 11H₂O, and the organic molecules, 2(pyCN)@CB[8]} · 16H₂O and {2(bpe)@CB[8]} · 17H₂O, where bipy is 4,4′-bipyridyl, pyCN is 4-cyanopyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene, were synthesized. The inclusion compounds with organic molecules were synthesized starting from inclusion compounds of cucurbit[8]uril with cyclam and ethylenediamine complexes of copper(II) and nickel(II) by the guest exchange method, which is based on the replacement of one guest with another in the cavity of the cavitand The resulting compounds were characterized by X-ray diffraction, ESR, ¹H NMR, IR, and electronic absorption spectroscopy, and electrospray mass spectrometry. Photochemically induced [2+2]-cycloaddition of two 1,2-bis(4-pyridyl)ethylene molecules included in cucurbit[8]uril was studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 25–34, January, 2006.     

Synthesis and electrochemical characterization of complexes of 1,2-bis[2-(pyridylmethylideneamino)phenylthio]ethanes with transition metals (CoII, NiII, CuII)

Transition metal (Ni^II, Co^II, and Cu^II) complexes with 1,2-bis[2-(3-pyridylmethylideneamino)phenylthio]ethane (1) and 1,2-bis[2-(4-pyridylmethylideneamino)phenylthio]ethane (2) were synthesized for the first time by slow diffusion of solutions of compounds 1 or 2 in CH₂Cl₂ into solutions of MX₂ · nH₂O (M = Ni, Co, or Cu; X = Cl or NO₃; n = 2 or 6) in ethanol. The reactions with Co^II and Cu^II chlorides afford complexes of composition M(L)Cl₂ (L = 1 or 2). The reactions of compound 1 with Ni^II salts produce complexes with 1,2-bis(2-aminophenylthio)ethane. The molecular structure of dinitrato[1,2-bis(2-aminophenylthio)ethane]nickel(ii) was confirmed by X-ray diffraction. The ligands and the complexes were investigated by cyclic voltammetry and rotating disk electrode voltammetry. The initial reduction of the complexes proceeds at the metal atom. The oxidation of the chlorine-containing complexes proceeds at the coordinated chloride anion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–355, February, 2008.     

Mononuclear complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), with 4-amino-3,5-bis(pyridin-2-yl)-1,2,4 triazole and tris(2-aminoethyl) amine: crystal structure of [Ni(tren)(abpt)](NO3)2(H2O)2.25

Complexes of the type [M(tren)(abpt)](NO₃)₂(H₂O)_n (1–6) [M = Mn^II, Fe^II, Co^II, Cu^II, Zn^II (n = 2), Ni^II (n = 2.25), tren = tris(2-aminoethyl)amine, and abpt = 4-amino-3,5-bis(pyridin-2yl)-1,2,4 triazole] have been prepared. The bonding mode and overall geometry of the complexes have been deduced by elemental analyses, molar conductance values, spectral studies (obtained from FT-IR), ¹H-n.m.r., electronic spectral analyses and magnetic susceptibility measurements. A detailed molecular structure of complex (4) has been determined by single X-ray crystallography.     

Interaction of manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) with acetylhydrazine, formed in situ; first crystal structure of tris(acetylhydrazine) nickel(II) perchlorate

A series of transition metal complexes of the type [M(ah)₃](ClO₄)₂ (1–6) [M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II and Zn^II, ah = acetylhydrazine] have been prepared by the reaction of M(ClO₄)₂ · 6H₂O with acetylhydrazine formed in situ by the reaction of hydrazine hydrate and acetylsalicylic acid methyl ester. The chelating behaviour of acetylhydrazine and overall geometry of these complexes have been spectroscopically investigated by means of FT-IR, ¹H-n.m.r. and electronic spectral techniques, as well as by elemental analysis data, molar conductance values and magnetic susceptibility measurements. Single X-ray structure determination of complex (4) revealed three acetylhydrazine ligands coordinated to nickel ion in a bidentate manner maintaining an octahedral environment. In all other complexes too, an octahedral geometry has been proposed on the basis of results obtained by various physico-chemical studies.     

Synthesis and Characterization of Two New Schiff Base Ligands and their Complexes with Cobalt(II), Nickel(II) and Copper(II)

Two Schiff base ligands, 2-{E-[(5-phenyl-6H-1,3,4-thiadiazin-2yl)imino]methyne}-1-naphthol (L¹H) and 5-nitro-2-{[(5-phenyl-6H-1,3,4-thiadiazin-2-yl)imino]methyne}phenol (L²H) have been prepared from 5-phenyl-6H-1,3,4-thiadiazin-2-amine (A), 2-hydroxynaphthaldehyde (1) and 2-hydroxy-5-nitrobenzaldehyde (2) Mononuclear Co(II), Ni^II and Cu^II complexes of the ligands have been prepared by using Co^II, Ni^II and Cu^II salts with a 1:2 metal:ligand ratio. It was determined that the bidentate behavior of the ligands is accomplished via the phenolic oxygen and the azomethine nitrogen atoms. The structures of the ligands and their complexes were identified by using elemental analyses, i.r., ¹H-n.m.r. spectra, electronic spectra, magnetic susceptibility measurements and thermogravimetric analyses (t.g.a.).     

Sodium cation migration above the diimine pi-system of solvent coordinated dpp-BIAN sodium aluminum complexes (dpp-BIAN=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene)

The reactions of the disodium salt of the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) ligand with one equivalent of Me2AlCl in diethyl ether, toluene, and benzene produced the complexes [Na(Et2O)2(dpp-BIAN)AlMe2] (1), [Na(eta6-C7H8)(dpp-BIAN)AlMe2] (2) and [Na(eta6-C6H6)(dpp-BIAN)AlMe2] (3), respectively. Recrystallization of 1 from hexane afforded solvent-free [{Na(dpp-BIAN)AlMe2}n] (4) or [Na(Et2O)(dpp-BIAN)AlMe2] (5) depending on the temperature of the solvent. The molecular structures of 1-5 have been determined by single-crystal X-ray diffraction. The sodium cation coordinates either one of the naphthalene rings (1) or the diimine part of the dpp-BIAN ligand (2-5). In the complexes 2 and 3, the sodium cation additionally coordinates the toluene (2) or benzene molecule (3) in an eta6-fashion.     

Acenaphthylene-1,2-diamine radical cation. Molecular structure of the [(dpp-BIAN)H2]·+[X]− complex ((dpp-BIAN)H2 is N,N′-bis(2,6-diisopropylphenyl)-acenaphthylene-1,2-diamine; X = Cl or I)

Oxidation of N,N′-bis(2,6-diisopropylphenyl)acenaphthylene-1,2-diamine (dpp-BIAN)H₂ with silicon tetrachloride or mercury(II) chloride affords the [(dpp-BIAN)H₂]·⁺[Cl]⁻ compound. The corresponding iodine derivative, [(dpp-BIAN)H₂]·⁺[I]⁻, was prepared by hydrolysis of the reaction products of the magnesium complex (dpp-BIAN)Mg(THF)₃ with tetraiodosilane. X-ray diffraction study demonstrated that the [(dpp-BIAN)H₂]^·+ radical cation in these compounds chelates the corresponding halide anion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 436–440, March, 2006.     

Ruthenium(II), rhodium(III) and iridium(III) based effective catalysts for hydrogenation under aerobic conditions

The new cationic mononuclear complexes [(η⁶-arene)Ru(Ph-BIAN)Cl]BF₄ [η⁶-arene = benzene (1), p-cymene (2)], [(η⁵-C₅H₅)Ru(Ph-BIAN)PPh₃]BF₄ (3) and [(η⁵-C₅Me₅)M(Ph-BIAN)Cl]BF₄ [M = Rh (4), Ir (5)] incorporating 1,2-bis(phenylimino)acenaphthene (Ph-BIAN) are reported. The complexes have been fully characterized by analytical and spectral (IR, NMR, FAB-MS, electronic and emission) studies. The molecular structure of the representative iridium complex [(η⁵-C₅Me₅)Ir(Ph-BIAN)Cl]BF₄ has been determined crystallographically. Complexes 1–5 effectively catalyze the reduction of terephthaldehyde in the presence of HCOOH/CH₃COONa in water under aerobic conditions and, among these complexes the rhodium complex [(η⁵-C₅Me₅)Rh(Ph-BIAN)Cl]BF₄ (4) displays the most effective catalytic activity.     

Isolation of an Imino‐N‐heterocyclic Carbene/Germanium(0) Adduct: A Mesoionic Germylene Equivalent

An autoionization of germanium dichloride/dioxane complex with an imino‐N‐heterocyclic carbene ligand ( L ) afforded a novel germyliumylidene ion, [( L )GeCl]⁺[GeCl₃]^?, which was fully characterized. Reduction of the germyliumylidene ion with potassium graphite produced a cyclic species [( L )Ge], which can be viewed as both a Ge⁰ species and a mesoionic germylene. X‐ray diffraction analysis and computational studies revealed one of the lone pairs on the Ge atom is involved in the π system on the GeC₂N₂ five‐membered ring. It was also confirmed that the nucleophilic behavior of [( L )Ge] as a two lone‐pair donor.     

Aldimine 2,6-bis(imino)pyridine iron(II) and cobalt(II)/methyl aluminoxane catalyst systems for polymerization of <Emphasis Type="Italic">tert-</Emphasis>butylacrylate

Aldimine 2,6-bis[(imino)methyl]pyridine iron(II) (1, 4, and 6) and cobalt(II) (3 and 5) complexes bearing bulky cycloaliphatic (bornyl and myrtanyl) or aromatic (naphthyl) terminal groups have been applied successfully, after activation with methyl aluminoxane (MAO), as catalysts for the polymerization of tert-butylacrylate. For comparison reasons, complex 2 that contains the ketimine ligand, 2,6-bis[(−)-cis-myrtanylimino)ethyl]pyridine (BMEP), has also been utilized. All studied complexes showed moderate polymerization activities, and they produced high molar mass syndiorich-atactic polymers. Surprisingly, the aldimine-based catalyst systems showed comparable activities compared with the corresponding ketimine complex (2), and they produced high molar mass polymers. In addition, complexes with bulky terminal cycloaliphatic substituents on the tridentate aldimine ligands showed higher polymerization activity compared with the aromatic ones (6). Polymerization activity and polymer molar masses are dependent on the ligand framework.