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.     

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.     

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.     

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.     

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.     

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.     

Reactions of germanium(II), tin(II), and antimony(III) chlorides with acenaphthene-1,2-diimines

Reactions of diimines dtb-BIAN and dph-BIAN with GeCl₂ afford germanium(II) complexes with radical-anionic ligands, (dtb-BIAN)GeCl (5) and (dph-BIAN)GeCl (6a), respectively, where dtb-BIAN is 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene and dph-BIAN is 1,2-bis[(2-biphenyl)imino]acenaphthene. The latter reaction gives 6a along with [(dph-BIAN)GeCl]⁺[GeCl₃]⁻ (6b). The reactions of tin(II) and antimony(III) chlorides with dtb-BIAN and dpp-BIAN produce complexes of these halides with neutral coordinated diimines, viz., (dtb-BIAN)SnCl₂ (7) and (dpp-BIAN)SbCl₃ (8) (dpp-BIAN is 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene). Paramagnetic complexes 5 and 6a were studied by ESR spectroscopy. Diamagnetic compounds 7 and 8 were characterized by ¹H NMR spectroscopy. The structures of complexes 5, 6a,b, 7, 8, and (dpp-BIAN)Ge (9) were established by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 71–80, January, 2006.     

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.     

Capture of phosphorus(I) and arsenic(I) moieties by a 1,2-bis(arylimino)acenaphthene (aryl-BIAN) ligand. A case of intramolecular charge transfer

The reaction of PCl3 with SnCl2 in THF solution, followed by treatment with dpp-BIAN (dpp = 2,6-i-Pr2C6H3), affords the phosphenium complex [(dpp-BIAN)P][SnCl5.THF]. The 31P chemical shift (delta 232.5) and the metrical parameters from a single-crystal X-ray diffraction study indicate that the oxidation state of phosphorus in this compound is +3. A similar conclusion was reached regarding the phosphorus oxidation state in [(dpp-BIAN)P][I3], which was prepared via the reaction of dpp-BIAN with PI3 in CH2Cl2 solution. The arsenium salt [(dpp-BIAN)As][SnCl5.THF] was prepared by treatment of AsCl3 with SnCl2 in THF solution, followed by the addition of dpp-BIAN. The X-ray crystal structure of this salt was determined, and the pattern of bond distances and angles indicates that arsenic is present in the +3 oxidation state.     

Spin‐State‐Controlled Photodissociation of Iron(III) Azide to an Iron(V) Nitride Complex

The generation of iron(V) nitride complexes, which are targets of biomimetic chemistry, is reported. Temperature‐dependent ion spectroscopy shows that this reaction is governed by the spin‐state population of their iron(III) azide precursors and can be tuned by temperature. The complex [(MePy₂TACN)Fe(N₃)]²⁺ (MePy₂TACN=N ‐methyl‐N ,N ‐bis(2‐picolyl)‐1,4,7‐triazacyclononane) exists as a mixture of sextet and doublet spin states at 300 K, whereas only the doublet state is populated at 3 K. Photofragmentation of the sextet state complex leads to the reduction of the iron center. The doublet state complex photodissociates to the desired iron(V) nitride complex. To generalize these findings, we show results for complexes with cyclam‐based ligands.     

Proton-Induced Spin State Switching in an FeIII Complex

Reversible proton-induced spin state switching of an Fe^III complex in solution is observed at room temperature. A reversible magnetic response was detected in the complex, [Fe^III(sal₂323)]ClO₄ ( 1 ), using Evans’ method ¹H NMR spectroscopy which indicated cumulative switching from low-spin to high-spin upon addition of one and two equivalents of acid. Infrared spectroscopy suggests a coordination-induced spin state switching (CISSS) effect, whereby protonation displaces the metal-phenoxo donors. The analogous complex, [Fe^III(4-NEt₂-sal₂323)]ClO₄ ( 2 ), with a diethylamino group on the ligand, was used to combine the magnetic change with a colorimetric response. Comparison of the protonation responses of 1 and 2 reveals that the magnetic switching is caused by perturbation of the immediate coordination sphere of the complex. These complexes constitute a new class of analyte sensor which operate by magneto-modulation, and in the case of 2 , also yield a colorimetric response.     

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.     

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.     

X-ray photoelectron spectra of heterometallic 3<Emphasis Type="Italic">d</Emphasis>-metal carboxylate complexes

The electronic structure and magnetic states in the heterometallic hexanuclear complex Mn₄^IIFe₂^III (μ₄-O)₂(Piv)₁₀ · MeCN₄ have been studied by X-ray photoelectron spectroscopy (XPS). The substitution of two Mn atoms for two Fe atoms in the hexanuclear complex was found to have an effect on the patterns of iron and manganese X-ray photoelectron spectra. XPS data are evidence of the high-spin paramagnetic state of Mn^II and Fe^III atoms, as well as of the ligand-metal charge transfer upon complex formation. In the heteroatomic complex, the degree of bond covalence increased for both the manganese and iron atoms. The results obtained are in good agreement with X-ray diffraction data.     

Palladium η3-allyl complex with sorbic acid: Kinetics and mechanism of protodemetalation in aqueous solutions

The allyl complex di-μ-chloro-bis[(1,2,3-η)-1-carboxy-3-(1-hydroxyethyl)allyl]dipalladium (which is a hydroxyl-containing palladium η³-allyl complex based on sorbic acid) has been synthesized from trans,trans-2,4-hexadienic (sorbic) acid and Na₂PdCl₄ in an aqueous solution. The complex has been isolated from the reaction solution and has been characterized by IR, ¹H NMR, and ¹³C NMR spectroscopy. Its composition has been determined by elemental analysis. The protodemetalation kinetics of the complex in aqueous solutions has been studied. The rate of this reaction obeys a second-order equation, first-order with respect to each reactant. A reaction mechanism has been derived from protodemetalation kinetics and data characterizing the state of the reactants.     

Dynamic behavior of [(η-C5H4CH3)Cr(CO)2(μ-SBu)Pt(PPh3)2] in solution

The structure and dynamic behavior of complex [(η⁵-C₅H₄CH₃)Cr(CO)₂(μ-SBu)Pt(PPh₃)₂] in solution was studied by multinuclear (¹H, ¹³C, ³¹P) NMR spectroscopy including a phase-sensitive NOESY experiment. Increasing temperature causes rupture of the Cr-Pt bond in the three-membered ring of the complex and rotation of the S-Pt(PPh₃)₂ unit around the Cr-S bond line, followed by formation of a new Cr-Pt bond to close the ring. All activation parameters for this dynamic process have been determined.     

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.     

[(bmpyr)2{Zn(OC6H3(NO2)2)4}]: Influence of an Ionic Liquid on Liquid/Liquid Extraction of Metal Ions in a Biphasic System

The compound [(bmpyr)₂{Zn(OR)₄}] (OR = 2,4‐dinitriphenolate) has been prepared from Zn(NO₃)₂·6H₂O and sodium 2,4‐dinitrophenolate in a biphasic aqueous ionic liquid (Butyl‐methyl‐pyrrolidinium trifluoromethylsulfonate [bmpyr][OTf]) system. The presence of the anionic zinc complex in [bmpyr][OTf] is made possible by the exchange of the ionic liquid anions into the aqueous phase for the zinc complex. [(bmpyr)₂{Zn(OR)₄}] was characterized in solution by ¹³C‐ and ¹H‐NMR spectroscopy and in the solid state by crystal structure determination. The zinc complex represents the first type of a zinc complex with more than two phenolate ligands.     

Silver(I) Complexes with Dithioether Ligands: Syntheses,Crystal Structures,and Fluorescence Properties

Two new dithioether ligands, 1,4‐bis[(phenylsulfanyl)methyl]naphthalene ( L¹ ), and 4,4′‐bis[(tert‐butylsulfanyl)methyl]biphenyl ( L² ) were synthesized and their silver(I) complexes were studied. Both Ag^I complexes, [Ag L¹ (NO₃)]_n ( 1 ) and [Ag L² (NO₃)]₂ ( 2 ), were synthesized at ambient temperature and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction analysis. Single‐crystal X‐ray analysis shows that complex 1 has a one‐dimensional helical chain structure with the neutral repeating unit [Ag(μ₂‐ L¹ )(NO₃)], whereas complex 2 has a centrosymmetrical neutral dinuclear structure. Moreover, complexes 1 and 2 are further extended into three‐dimensional supramolecular frameworks by hydrogen bonding and π–π stacking interactions, respectively. In addition, complexes 1 and 2 display strong blue emission in the solid state at room temperature.     

Synthesis and Mössbauer spectroscopy of oxo-centered mixed-valence trinuclear iron fumarate and iron malonate complexes

Oxo-centered trinuclear mixed-valence iron fumarate [Fe₃O(O₂CCH=CHCO₂)₃(H₂O)₃]^·nH₂O and iron malonate [Fe₃O(O₂CCH₂CO₂)₃(H₂O)₃] have been prepared and studied by variable temperature Mössbauer spectroscopy. Iron fumarate complex showed a temperature dependent valence delocalization process. At 6 K two quadrupole split doublets corresponding to high-spin Fe(III) and high-spin Fe(II) state with an area ratio of 2:1 were observed and at 298 K there was only an averaged singlet peak. On the other hand malonate complex showed a localized valence state of high-spin Fe(III) and Fe(II) from low temperature to room temperature only with a slight variation in area ratio and spectral line broadening for Fe(II).