Stannylenes based on neutral,anionic, and dianionic 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Russian Chemical Bulletin - The reaction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian (1)) with one equivalent of SnCl2 gave the complex [(dpp-bian)0SnCl2] (2) containing the...     

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.     

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.     

Addition of phenylacetylene and camphor to the complex [(dpp-bian)Eu(dme)<Subscript>2</Subscript>] (dpp-bian is the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene dianion)

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with an excess of europium metal in 1,2-dimethoxyethane (dme) produces a divalent europium complex with the dpp-bian dianion, [(dpp-bian)Eu(dme)₂] (1). The reactions of 1 with phenyl-acetylene and camphor proceed via protonation of the diimine ligand to form the monomeric amido-amino complexes of divalent europium — [H(dpp-bian)Eu(C≡CPh)(dme)₂] (2) and [H(dpp-bian)Eu(camphor)(dme)₂] (3), respectively. Compounds 2 and 3 were characterized by IR spectroscopy and elemental analysis. Their molecular structures were determined by X-ray diffraction. Compounds 2 and 3 were shown to be monomeric seven-coordinate europium(ii) complexes with terminal phenylethynyl and enol ligands, respectively. According to the IR spectroscopic data, the terminal ligands in complexes 2 and 3 undergo tautomerization involving backward proton transfer from the amido-amino ligand to the substrate. The magnetic moment of compound 2 (8.03 μB) remains constant in the temperature range of 4—300 К and confirms the presence of divalent europium.     

1,3,2-Diazasiloles derived from 1,2-bis(trimethylsilylimino)acenaphthene

The reduction of 1,2-bis(trimethylsilylimino)acenaphthene (tms-BIAN, 1) with metallic lithium in toluene affords the dilithium salt (tms-BIAN)Li_2· 1,3,2-Diazasiloles (tms-BIAN)SiCl₂ (2) and (tms-BIAN)SiMe₂ (3) were prepared by the reactions of (tms-BIAN)Li₂ with SiCl₄ and Me₂SiCl₂, respectively. The reaction of (tms-BIAN)Li₂ with an excess of Me₂SiCl₂ produces (Cldms-BIAN)SiMe₂ (4), where Cldms-BIAN is 1,2-bis(chlorodimethylsilylimino)-acenaphthene. The compound (tms-BIAN)(SiCl₃)₂ (5) containing two different silyl substituents (Me₃Si and Cl₃Si) at each nitrogen atom was synthesized by the reaction of compound 1 with Cl₃SiSiCl₃. The elimination of SiCl₄ from compound 5 is accompanied by cyclization to give derivative 2. Compounds 2-5 were characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy. The crystal structures of 2-5 were established by X-ray diffraction.     

Mononuclear gallium complexes with the redox-active dmp-bian ligand (dmp-bian is 1,2-bis[(2,6-dimethylphenyl)imino]acenaphthene): synthesis and reactions with alkynes

Russian Chemical Bulletin - The direct reduction of 1,2-bis[(2,6-dimethylphenyl)imino]acenaphthene (dmp-bian (1)) with gallium metal in toluene affords the solvent-free bis-ligand complex...     

Samarium and ytterbium complexes based on sterically hindered 1,2-bis(imino)acenaphthene*

Russian Chemical Bulletin - Reactions of the samarium complex [(ArBIG-bian)2?Sm2+] (1) (ArBIG-bian is the 1,2-bis-[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene dianion) with iodine...     

New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

1,2-Bis[(trimethylsilyl)imino]acenaphthene (1) was synthesized by the reaction of acenaphthenequinone with (Me₃Si)₂NLi in toluene followed by treatment of the reaction product with trimethylchlorosilane. The dianionic derivative [(tms-BIAN)Li₂]₂ (3) was obtained as the final product by reduction of compound 1 with lithium in toluene, whereas reduction in diethyl ether afforded the tetraanion [(tms-BIAN)Li₄(Et₂O)₃]₂ (5). The formation of the paramagnetic mono-and trianions in solution was confirmed by ESR spectroscopy. Compounds 3 and 5 were isolated in the crystalline state and characterized by elemental analysis, IR spectroscopy, and NMR spectroscopy. The crystal structures of 1, 3, and 5 were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 697–705, April, 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.     

Synthesis and Molecular Structure of Two Zinc Complexes of 1,2‐Bis[(trimethylsilyl)imino]acenaphthene

The reaction of 1,2‐bis[(trimethylsilyl)imino]acenaphthene ( 1 , tms‐BIAN) with ZnCl₂ and ZnI₂ in THF and Et₂O afford (tms‐BIAN)ZnCl₂ ( 2 ) and (tms‐BIAN)ZnI₂ ( 3 ), respectively. The compounds 2 and 3 were characterized by IR‐ and NMR spectroscopy as well as by single crystal X‐ray analysis.     

Addition of nitriles to alkaline earth metal complexes of 1,2-bis[(phenyl)imino]acenaphthenes

Compounds [Sr(dpp-bian)(thf)4] (2), [Ba(dpp-bian)(dme)2.5] (3) and [Mg(dtb-bian)(thf)2] (4) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene; dtb-bian = 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were prepared by reduction of dpp-bian and dtb-bian with an excess of metallic Mg, Sr, or Ba in THF or DME. Reactions of [Mg(dpp-bian)(thf)3], 3, and 4 with diphenylacetonitrile gave keteniminates [Mg(dpp-bianH)(NCCPh2)(thf)2] (5), [Mg(dtb-bianH)(NCCPh2)(thf)2] (6), and [Ba(dpp-bianH)(NCCPh2)(dme)2] (7), respectively. The reaction of 2 with CH3C[triple chemical bond]N in THF gave [{Sr(dpp-bianH)[N(H)C(CH3)C(H)CN](thf)}2] (8). The compounds 2, 3, 5-8 were characterized by elemental analysis, and IR and NMR spectroscopy. Molecular structures of 2, 3, 7, and 8 were determined by single-crystal X-ray diffraction. In contrast to reactions of alkali-metal reagents, magnesium amides, or yttriumalkyls with alpha-H acidic nitriles, which are accompanied by an amine or an alkane elimination, the reactions of [Mg(dpp-bian)(thf)3] (1), 2, 3, and 4 with such nitriles proceeded with formation of Mg, Sr, and Ba keteniminates and simultaneous protonation of one nitrogen atom of the bian ligand. The NMR spectroscopic data obtained for complex 5 indicated that in solution the amino hydrogen atom underwent the fast (on the NMR timescale) shuttle transfer between both nitrogen atoms of the dpp-bianH ligand.     

Synthesis and Structural Studies of Group 2B Transition Metal Complexes with the Bulky Nitrogen Ligand Bis[ N-(2,6-diisopropylphenyl) imino]acenaphthene

Group 2B transition metal complexes of bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (o,o-iPr₂C₆H₃-BIAN), namely, [Hg(o,o-iPr₂C₆H₃-BIAN)Cl₂] (1), [Zn(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (2), and [Cd(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (3) have been synthesized and characterized. In complexes 2 and 3, IR, NMR, and conductivity measurements confirm the coordination of two (o,o-iPr₂C₆H₃-BIAN) ligands to the metal center with two discrete perchlorate anions. X-Ray crystal structure of 1 indicates a distorted tetrahedral geometry with two nitrogen atoms from (o,o-iPr₂C₆H₃-BIAN) ligand and two chloride atoms coordinating to the Hg(II) center.     

Divalent germanium compound with a radical-anionic ligand: molecular structures of (dpp-BIAN)*- GeCl and its hydrochloration products [(dpp-BIAN)(H)2]*+ [GeCl3]- and [[(dpp-BIAN)(H)2*+]2(Cl-)]+ [GeCl3]- (dpp-BIAN=1,2-Bis[(2,6-diisopropylphenyl)imino]acenaphthene)

The germanium(II) compound (dpp-BIAN)GeCl (1), which contains the radical anion of dpp-BIAN can be prepared either by reacting free dpp-BIAN ligand with 2 equiv of GeCl2(1,4-dioxane) in Et2O or by metathetical reaction of the sodium salt of dpp-BIAN with germanium dichloride in Et2O or benzene. The reaction of benzene solutions of 1 with 2 or 3 equiv of HCl led to protonation of the dpp-BIAN ligand affording [(dpp-BIAN)(H)2]*+[GeCl3]- (2) and [[(dpp-BIAN)(H)2*+]2(Cl-)]+ [GeCl3]- (3), which incorporate the radical cation of the protonated ligand. Compounds 1-3 have been characterized by elemental analysis, IR, UV-vis, and electron spin resonance (ESR) spectroscopy. Molecular structures of 1-3 were determined by single-crystal X-ray diffraction. In molecule 1, the Ge atom is positioned at the apex of the slightly distorted trigonal pyramid. The Ge-N bond lengths in 1 are 2.0058(19) and 2.004(2) A. The molecular structure of 2 consists of contact ions [(dpp-BIAN)(H)2]+ and [GeCl3]-. In the molecular structure of 3, two radical cations of [(dpp-BIAN)(H)2]+ are "coordinated" by the chlorine anion. The ESR signal of 1 indicates the presence of a dpp-BIAN radical anion and shows a hyperfine structure due to the coupling of an unpaired electron to 14N, 73Ge, 35Cl, 37Cl, and 1H nuclei (AN=0.48 (2 N), AGe=0.96, ACl=0.78 (35Cl), ACl=0.65 (37Cl), AH=0.11 (4 H) mT, g=2.0014). Both 2 and 3 reveal ESR signals of radical cation [(dpp-BIAN)(H)2]*+ (septet, AN=0.53, AH=0.48 mT, g=2.0031).     

Chemistry of the heavy group 15 elements with the pyridyl tethered 1,2-bis(imino)acenaphthene "clamshell" ligand

Cobaltocene has been used as a one-electron reductant in a facile route to generate pnictogen(I) (P, As) synthons. These subsequently undergo a formal 4 + 2 cycloaddition with a pyridyl tethered 1,2-bis(imino)acenaphthene "clamshell" ligand to yield N-heterocyclic chlorophosphines and -arsines, which are precursors to the corresponding N-heterocyclic pnictenium cations. In the absence of a reductant the "clamshell" ligand can be used in forming hypervalent donor-acceptor complexes with heavy main group elements (Sn, Sb and Bi).