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1.
Chem Commun (Camb) ; 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32496503

RESUMO

The reductive coupling of carbodiimides RN[double bond, length as m-dash]C[double bond, length as m-dash]NR (R = 2,6-iPr2C6H3, Cy, iPr) by using [(dpp-bian)GaNa(dme)2] (1); [(dpp-dad)GaNa(thf)3] (2a) and [(dpp-dad)GaK(thf)4Ga(dpp-dad)][K(thf)6] (2b) led to the guanidinate derivatives [(dpp-bian)Ga(NCy)2C[double bond, length as m-dash]NCy][Na(thf)2] (3); [LGaN(R)C(RN)N(R)C(RN)][M] L = dpp-bian, M = Na(dme)2, R = iPr, (4a); L = dpp-dad, M = Na(thf)3, R = iPr, (4b); R = Cy, (4c); M = K(thf)4, (4d); L = dpp-bian, M = Na(dme)2, R = Cy, (4e) and [(dpp-dad)Ga(2,6-iPr2C6H3N)2C][Na(thf)2] (5).

2.
Dalton Trans ; 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-32073071

RESUMO

The reduction of [(dpp-bian)BBr] (1, dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with dilithium naphthalenide in Et2O gives [{(dpp-bian)BBr}Li2(Et2O)2]2 (3). The treatment of [(dpp-bian)BONa] (5) and [(dpp-bian)Ge:] (7) with sodium is accompanied by protonation of the acenaphthylene fragment and affords [{(H-dpp-bian)BONa(dme)2}Na(dme)3] (6) and [(H-dpp-bian)Ge:][Na(dme)3] (8), respectively. Compounds 3, 6 and 8 have been characterized by 1H NMR and IR spectroscopy. The molecular structures of 3, [(dpp-bian)BOK] (4) and 8 have been established by single crystal X-ray analysis.

3.
Inorg Chem ; 58(24): 16559-16573, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31689094

RESUMO

The synthesis of electron-deficient gallium- and aluminum-centered species containing a redox-active dpp-Bian ligand (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) is described. The reaction of digallane [(dpp-Bian)Ga-Ga(dpp-Bian)] with [Ph3C][PF6] or AgPF6 resulted in polyoxidized species [(dpp-Bian)GaF2]2 (1), [(dpp-Bian)H2][PF6] (2), and [(dpp-Bian)GaF(O2PF2)]2 (3). The reaction of digallane with B(C6F5)3 led to electron-deficient gallylene [(dpp-Bian)GaB(C6F5)3] 4 of a dpp-Bian radical anion. The soft oxidation of digallane with tosyl cyanide gave the trinuclear cationic species [(dpp-Bian)Ga(Tos)3Ga(Tos)3Ga(dpp-Bian)][Ga(CN)4] (5) containing dpp-Bian radical anions. The reaction of [(dpp-Bian)AlEt2] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the cationic complex [(dpp-Bian)AlEt2][B(C6F5)4] (6) of neutral dpp-Bian, while the treatment of [(dpp-Bian)AlEt(Et2O)] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the compound [(dpp-Bian)AlEt(Et2O)][B(C6F5)4] (7) of a dpp-Bian radical anion. The reaction of diethylaluminum derivative [(dpp-Bian)AlEt2] with 1 equiv of B(C6F5)3 gave the cationic complex [{(dpp-Bian)AlEt}2F][EtB(C6F5)3] (8) containing radical-anion dpp-Bian ligands. The paramagnetic compounds 1, 2, 4, 5, 7, and 8 were characterized by electron paramagnetic resonance spectroscopy, and the diamagnetic complex 6 was characterized by NMR spectroscopy. The molecular structures of 1-6 and 8 were established by single-crystal X-ray diffraction analysis. Compounds 4 and 6-8 were found to be active initiators for immortal ring-opening polymerization of ε-caprolactone.

4.
Chem Asian J ; 14(17): 2979-2987, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31298502

RESUMO

New nickel-based complexes of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with BF4 - counterion or halide co-ligands were synthesized in THF and MeCN. The nickel(I) complexes were obtained by using two approaches: 1) electrochemical reduction of the corresponding nickel(II) precursors; and 2) a chemical comproportionation reaction. The structural features and redox properties of these complexes were investigated by using single-crystal X-ray diffraction (XRD), cyclic voltammetry (CV), and electron paramagnetic resonance (EPR) and UV/Vis spectroscopy. The influence of temperature and solvent on the structure of the nickel(I) complexes was studied in detail, and an uncommon reversible solvent-induced monomer/dimer transformation was observed. In the case of the fluoride complex, the unpaired electron was found to be localized on the dpp-bian ligand, whereas all of the other nickel complexes contained neutral dpp-bian moieties.

5.
Chemistry ; 25(35): 8259-8267, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-30892746

RESUMO

Digallane [L1 Ga-GaL1 ] (1, L1 =dpp-bian=1,2-[(2,6-iPr2 C6 H3 )NC]2 C12 H6 ) reacts with RN=C=O (R=Ph or Tos) by [2+4] cycloaddition of the isocyanate C=N bonds across both of its C=C-N-Ga fragments to afford [L1 (O=C-NR)Ga-Ga(RN-C=O)L1 ] (R=Ph, 3; R=Tos, 4). The reactions with both isocyanates result in new C-C and N-Ga single bonds. In the case of allyl isocyanate, the [2+4] cycloaddition across one C=C-N-Ga fragment of 1 is accompanied by insertion of a second allyl isocyanate molecule into the Ga-N bond of the same fragment to afford compound [L1 Ga-Ga(AllN- C=O)2 L1 ] (5) (All=allyl). In the presence of Na metal, the related digallane [L2 Ga-GaL2 ] (2; L2 =dpp-dad=[(2,6-iPr2 C6 H3 )NC(CH3 )]2 ) is converted into the gallium(I) carbene analogue [L2 Ga:]- (2 A), which undergoes a variety of reactions with isocyanate substrates. These include the cycloaddition of ethyl isocyanate to 2 A affording [Na2 (THF)5 ]{L2 Ga[EtN-C(O)]2 GaL2 } (6), cleavage of the N=C bond with release of 1 equiv. of CO to give [Na(THF)2 ]2 [L2 Ga(p-MeC6 H4 )(N-C(O))2 -N(p-MeC6 H4 )]2 (7), cleavage of the C=O bond to yield the di-O-bridged digallium compound [Na(THF)3 ]2 [L2 Ga-(µ-O)2 -GaL2 ] (8), and generation of the further addition product [Na2 (THF)5 ][L2 Ga(CyNCO2 )]2 (9). Complexes 3-9 have been characterized by NMR (1 H, 13 C), IR spectroscopy, elemental analysis, and X-ray diffraction analysis. Their electronic structures have been examined by DFT calculations.

6.
Chemistry ; 25(15): 3858-3866, 2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30570195

RESUMO

The electrochemical characteristics of 2-mono(2,6-diisopropylphenylimino)acenaphthene-1-one (dpp-mian) have been investigated. One-electron reduction of dpp-mian involves the iminoketone fragment, which is revealed by the EPR spectrum obtained after the electrolysis of the dpp-mian solution in tetrahydrofuran (THF). The reduction of dpp-mian with one equivalent of metallic potassium leads to a similar EPR spectrum. The sodium complex [(dpp-mian)Na(dme)]2 (1) produces an EPR signal with hyperfine coupling on the nitrogen atom of the iminoketone fragment of the dpp-mian ligand. Dpp-mian can also be reduced in a one-electron process by SnCl2 ×(dioxane). In this case, complex (dpp-mian)2 SnCl2 (2) is formed, with the tin atom displaying an oxidation state of +4. Tin(II) chloride dihydrate, SnCl2 ×2(H2 O), also reduces dpp-mian, but the two ligands bound to tin in the product form a new carbon-carbon bond between the ketone moieties of the dpp-mian monoanions to form complex (bis-dpp-mian)HSnCl3 (3). Metallic tin reduces dpp-mian to form the (bis-dpp-mian)2 Sn (4) species. Compounds 1-4 were characterized by X-ray diffraction.

7.
Chem Commun (Camb) ; 54(92): 12950-12953, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30383054

RESUMO

Reduction of [(dpp-bian)2-M2+(thf)4] (M = Ca, 1; Yb, 6; dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) by alkali metals results in heterometallic, [(dpp-bian)3-M2+K+(thf)2]2 (M = Ca, 2; Yb, 7), [(dpp-bian)4-Ca2+A2+(thf)4]2 (A = Na, 3; Li, 4; K, 5), [(dpp-bian)4-Yb2+K2+(thf)4]2 (8) and [(dpp-bian)24-Yb32+K2+(thf)8] (9). The reduction of [(dpp-bian)TmBr(thf)n] (in situ) affords [(dpp-bian)4-Tm3+Na+(thf)]2 (10).

8.
Dalton Trans ; 47(39): 13800-13808, 2018 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-30106082

RESUMO

The present study first describes the reactivity of low valent Al(ii) and Ga(ii) complexes of the type (dpp-bian)M-M(dpp-bian) (1, M = Al; 2, Ga; dpp-bian2- = 1,2-bis-(2,6-iPr2-C6H3)-acenaphthenequinonediamido) with cyclic esters/carbonates such as ε-caprolactone (CL) and trimethylene carbonate (TMC). CL and TMC both readily coordinate to the Al(ii) species 1 to form the corresponding bis-adducts (dpp-bian)Al(L)-(L)Al(dpp-bian) (3, L = CL; 4, L = TMC), which were structurally characterized confirming that the Al(ii)-Al(ii) dimetallic backbone retains its integrity in the presence of such cyclic polar substrates. In contrast, the less Lewis acidic Ga(ii) analogue 2 shows no reaction in the presence of stoichiometric amounts of CL and TMC at room temperature. In combination with BnOH, the dinuclear Al(ii) species 1 revealed to be an extremely active Al(ii) initiator for the controlled ROP of CL at room temperature, outperforming all its Al(iii) congeners reported thus far. Detailed DFT studies on the ROP mechanism are consistent with a process occurring thanks to the metallic cooperativity between the two Al(ii) proximal (since directly bonded) metal centers in 1, which undoubtedly favors the ROP process through bimetallic activation and thus rationalizes the unusually high CL ROP activity at room temperature.

9.
Chemistry ; 24(56): 14994-15002, 2018 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-30016556

RESUMO

Whereas the chemistry of single-bond activation by compounds of the main group elements has undergone some development in recent years, the cleavage of multiple bonds remains underexplored. Herein, the reactions of two digallanes bearing α-diimine ligands, namely, [L1 Ga-GaL1 ] (1, L1 =dpp-dad=[(2,6-iPr2 C6 H3 )NC(CH3 )]2 ) and [L2 Ga-GaL2 ] (2, L2 =dpp-bian=1,2-[(2,6-iPr2 C6 H3 )NC]2 C10 H6 ), with isothiocyanates are reported. Reactions of 1 or 2 with isothiocyanates in 1:2 molar ratio proceeded with [2+4] cycloaddition of the C=S bond across the C2 N2 Ga metallacycle with formation of C-C and S-Ga single bonds to afford [L1 (RN=C-S)Ga-Ga(S-C=NR)L1 ] (3, R=Me; 4, R=Ph) and [L2 (RN=C-S)Ga-Ga(S-C=NR)L2 ] (8, R=allyl; 9, R=Ph). In the cases of 8 and 9, this cycloaddition is reversible. The digallanes reacted with 2 equiv of PhNCS in the presence of Na metal or at high temperatures through a unique reductive cleavage of the C=S bond to yield the disulfide-bridged digallium species [Na(THF)3 ]2 [L1 Ga(µ-S)2 GaL1 ] (5), [L2 Ga(µ-S)2 GaL2 ] (10), and [Na(DME)3 ][L2 Ga(µ-S)2 GaL2 ] (11). Moreover, products 4 and 5 can further react with an excess of isothiocyanate, through cleavage of the C=S bond or cycloaddition, to give the bis- or mono-S-bridged complexes [Na(THF)2 ]2 [L1 (PhN=C-S)Ga(µ-S)2 Ga(S-C=NPh)L1 ] (6) and [L1 (PhN=C-S)Ga(µ-S)Ga(S-C=NPh)L1 ] (7). All the newly prepared compounds were characterized by elemental analysis, single-crystal X-ray diffraction, IR spectroscopy, NMR (3-9) or ESR spectroscopy (11), and DFT calculations.

10.
Inorg Chem ; 57(8): 4301-4309, 2018 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-29561149

RESUMO

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-Bian) with an excess of La metal in the presence of iodine (dpp-Bian/I2 = 2/1) in tetrahydrofuran (thf) or dimethoxyethane (dme) affords lanthanum(III) complexes of dpp-Bian dianion: deep blue [(dpp-Bian)2-LaI(thf)2]2 (1, 84%) was isolated by crystallization of the product from hexane, while deep green [(dpp-Bian)LaI(dme)2] (2, 93%) precipitated from the reaction mixture in the course of its synthesis. A treatment of complex 1 with 0.5 equiv of I2 in thf leads to the oxidation of the dpp-Bian dianion to the radical anion and results in the complex [(dpp-Bian)1-LaI2(thf)3] (3). Addition of 18-crown-6 to the mixture of 1 and NaCp* (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl) in thf affords ionic complex [(dpp-Bian)2-La(Cp*)I][Na(18-crown-6)(thf)2] (4, 71%). In the absence of crown ether the alkali metal salt-free complex [(dpp-Bian)2-LaCp*(thf)] (5, 67%) was isolated from toluene. Reduction of complex 1 with an excess of potassium produces lanthanum-potassium salt of the dpp-Bian tetra-anion {[(dpp-Bian)4-La(thf)][K(thf)3]}2 (6, 68%). Diamagnetic compounds 1, 2, 4, 5, and 6 were characterized by NMR spectroscopy, while paramagnetic complex 3 was characterized by the electron spin resonance spectroscopy. Molecular structures of 2-6 were established by single-crystal X-ray analysis.

11.
Chemistry ; 24(8): 1877-1889, 2018 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-29125198

RESUMO

The reaction of digallane (dpp-bian)Ga-Ga(dpp-bian) (2) (dpp-bian=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with allyl chloride (AllCl) proceeded by a two-electron oxidative addition to afford paramagnetic complexes (dpp-bian)Ga(η1 -All)Cl (3) and (dpp-bian)(Cl)Ga-Ga(Cl)(dpp-bian) (4). Treatment of complex 4 with pyridine induced an intramolecular redox process, which resulted in the diamagnetic complex (dpp-bian)Ga(Py)Cl (5). In reaction with allyl bromide, complex 2 gave metal- and ligand-centered addition products (dpp-bian)Ga(η1 -All)Br (6) and (dpp-bian-All)(Br)Ga-Ga(Br)(dpp-bian-All) (7). The reaction of digallane 2 with Ph3 SnNCO afforded (dpp-bian)Ga(SnPh3 )2 (8) and (dpp-bian)(NCO)Ga-Ga(NCO)(dpp-bian) (9). Treatment of GaCl3 with (dpp-bian)Na in diethyl ether resulted in the formation of (dpp-bian)GaCl2 (10). Diorganylgallium derivatives (dpp-bian)GaR2 (R=Ph, 11; tBu, 14; Me, 15; Bn, 16) and (dpp-bian)Ga(η1 -All)R (R=nBu, 12; Cp, 13) were synthesized from complexes 3, 10, Bn2 GaCl, or tBu2 GaCl by salt metathesis. The salt elimination reaction between (dpp-bian)GaI2 (17) and tBuLi was accompanied by reduction of both the metal and the dpp-bian ligand, which resulted in digallane 2 as the final product. Similarly, the reaction of complex 10 with MentMgCl (Ment=menthyl) proceeded with reduction of the dpp-bian ligand to give the diamagnetic complex [(dpp-bian)GaCl2 ][Mg2 Cl3 (THF)6 ] (18). Compounds 11, 12, 13, 15, and 16 were thermally robust, whereas compound 14 decomposed when heated at reflux in toluene to give complex (dpp-bian-tBu)GatBu2 (19). Both complexes 7 and 19 contain R-substituted dpp-bian ligand: in the former compound the allyl group was attached to the imino-carbon atom, whereas in complex 19, the tBu group was situated on the naphthalene ring. Crystal structures of complexes 3, 8, 9, 10, 13, 14, 18, and 19 were determined by single-crystal X-ray analysis. The presence of dpp-bian radical anions in 3, 6, 8, and 10-16 was determined by ESR spectroscopy.

12.
Inorg Chem ; 56(21): 13401-13410, 2017 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-29023115

RESUMO

The reaction of Cl2GaH with a sodium salt of the dpp-Bian radical-anion (dpp-Bian•-)Na (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) affords paramagnetic gallane (dpp-Bian•-)Ga(Cl)H (1). Oxidation of (dpp-Bian2-)Ga-Ga(dpp-Bian2-) (2) with N2O results in the dimeric oxide (dpp-Bian•-)Ga(µ2-O)2Ga(dpp-Bian•-) (3). A treatment of the oxide 3 with phenylsilane affords paramagnetic gallium hydrides (dpp-Bian•-)GaH2 (4) and (dpp-Bian•-)Ga{OSi(Ph)H2}H (5) depending on the reagent's stoichiometry. The reaction of digallane 2 with benzaldehyde produces pinacolate (dpp-Bian•-)Ga(O2C2H2Ph2) (6). In the presence of PhSiH3, the reaction between digallane 2 and benzaldehyde (2: PhSiH3: PhC(H)O = 1:4:4) affords compound 4. The newly prepared complexes 1, 3-6 consist of a spin-labeled diimine ligand-dpp-Bian radical-anion. The presence of the ligand-localized unpaired electron allows the use of the ESR spectroscopy for characterization of the gallium hydrides reported. The molecular structures of compounds 1, 3-6 have been determined by the single-crystal X-ray analysis.

13.
Inorg Chem ; 56(16): 9825-9833, 2017 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-28786665

RESUMO

The reaction of (dpp-Bian)EuII(dme)2 (3) (dpp-Bian is dianion of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene; dme is 1,2-dimethoxyethane) with 2,2'-bipyridine (bipy) in toluene proceeds with replacement of the coordinated solvent molecules with neutral bipy ligands and affords europium(II) complex (dpp-Bian)EuII(bipy)2 (9). In contrast the reaction of related ytterbium complex (dpp-Bian)YbII(dme)2 (4) with bipy in dme proceeds with the electron transfer from the metal to bipy and results in (dpp-Bian)YbIII(bipy)(bipy-̇) (10) - ytterbium(III) derivative containing both neutral and radical-anionic bipy ligands. Noteworthy, in both cases dianionic dpp-Bian ligands retain its reduction state. The ligand-centered redox-process occurs when complex 3 reacts with N,N'-bis[2,4,6-trimethylphenyl]-1,4-diaza-1,3-butadiene (mes-dad). The reaction product (dpp-Bian)EuII(mes-dad)(dme) (11) consists of two different redox-active ligands both in the radical-anionic state. The reduction of 3,6-di-tert-butyl-4-(3,6-di-tert-butyl-2-ethoxyphenoxy)-2-ethoxycyclohexa-2,5-dienone (the dimer of 2-ethoxy-3,6-di-tert-butylphenoxy radical) with (dpp-Bian)EuII(dme)2 (3) caused oxidation of the dpp-Bian ligand to radical-anion to afford (dpp-Bian)(ArO)EuII(dme) (ArO = OC6H2-3,6-tBu2-2-OEt) (12). The molecular structures of complexes 9-12 have been established by the single crystal X-ray analysis. The magnetic behavior of newly prepared compounds has been investigated by the SQUID technique in the range 2-310 K. The isotropic exchange model has been adopted to describe quantitatively the magnetic properties of the exchange-coupled europium(II) complexes (11 and 12). The best-fit isotropic exchange parameters are in good agreement with their density functional theory-computed counterparts.

14.
Dalton Trans ; 46(24): 7857-7865, 2017 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-28598473

RESUMO

Reaction of the Ni-Ni-bonded compound [(NiIL˙-)2] (1, L = [(2,6-iPr2C6H3)NC(Me)]2) with various 1,2-diketones afforded a series of heteroleptic complexes: [LNi(PhC(O)-C(O)Ph)] (2), [LNi(PhC(O)-C(O)Me)] (3), [LNi(3,5-tBu2C6H2O2)] (4), and [(LNi){µ-η2,η2-(MeC(O)-C(O)Me)}(NiL)] (5). Furthermore, the complex [Na(Et2O)][LNi{PhC(O)-C(O)Ph}] (6) was obtained by the reduction of 2 with 1.0 equiv. of Na metal. These complexes, which contain three potential redox-active centers, nickel and both α-diimine and 1,2-diketone ligands, were characterized by X-ray crystallography, NMR, EPR, and UV-vis-NIR spectra, magnetic susceptibility measurements, and DFT computations to elucidate their electronic structures.

15.
Inorg Chem ; 55(17): 9047-56, 2016 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-27548713

RESUMO

The reactivity of digallane (dpp-Bian)Ga-Ga(dpp-Bian) (1) (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of 1 with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)Ga(µ2-AcQ)Ga(dpp-Bian) (2), in which diolate [AcQ](2-) acts as "bracket" for the Ga-Ga bond. The interaction of 1 with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga-Ga bond to give (dpp-Bian)Ga(µ2-AcQ)2Ga(dpp-Bian) (3). At 330 K in toluene complex 2 decomposes to give compounds 3 and 1. The reaction of complex 2 with atmospheric oxygen results in oxidation of a Ga-Ga bond and affords (dpp-Bian)Ga(µ2-AcQ)(µ2-O)Ga(dpp-Bian) (4). The reaction of digallane 1 with SO2 produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)Ga(µ2-O2S-SO2)Ga(dpp-Bian) (5) and (dpp-Bian)Ga(µ2-O2S-SO2)2Ga(dpp-Bian) (6). In compound 5 the Ga-Ga bond is preserved and supported by dithionite dianionic bracket. In compound 6 the gallium centers are bridged by two dithionite ligands. Both 5 and 6 consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane 1 leads to complex (dpp-Bian)Ga(µ2-NPh)2Ga(dpp-Bian) (7). Paramagnetic compounds 2-7 were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds 2, 5, and 6 was investigated by superconducting quantum interference device technique in the range of 2-295 K.

16.
Chem Commun (Camb) ; 50(70): 10108-11, 2014 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-25050806

RESUMO

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.

17.
Inorg Chem ; 53(10): 5159-70, 2014 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-24809210

RESUMO

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. Treatment of compound 3 with B(C6F5)3 leads to removal of pyridine and restores compound 2. The reaction of compound 1 with 3,6-di-tert-butyl-ortho-benzoquinone (3,6-Q) proceeds with oxidation of all the redox-active centers in 1 (the Ga-Ga bond and two dpp-Bian dianions) and results in mononuclear catecholate (dpp-Bian)Ga(Cat) (4) (Cat = [3,6-Q](2-)). Treatment of 4 with AgBF4 gives a mixture of [(dpp-Bian)2Ag][BF4] (5) and (dpp-Bian)GaF(Cat) (6), which both consist of neutral dpp-Bian ligands. The reduction of benzylideneacetone (BA) with 1 generates the BA radical-anions, which dimerize, affording (dpp-Bian)Ga-(BA-BA)-Ga(dpp-Bian) (7). In this case the Ga-Ga bond remains unchanged. Within 10 min at 95 °C in solution compound 7 undergoes transformation to paramagnetic complex (dpp-Bian)Ga(BA-BA) (8) and metal-free compound C36H40N2 (9). The latter is a product of intramolecular addition of the C-H bond of one of the iPr groups to the C═N bond in dpp-Bian. Diamagnetic compounds 3, 5, 6, and 9 have been characterized by NMR spectroscopy, and paramagnetic complexes 2, 4, 7, and 8 by ESR spectroscopy. Molecular structures of 2-7 and 9 have been established by single-crystal X-ray analysis.

18.
Dalton Trans ; 42(22): 7952-61, 2013 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-23435476

RESUMO

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). Treatment of 2 with potassium hydroxide afforded complexes (dpp-bian)B-OH (5) and (dpp-bian)B-OK (6). Boron amide (dpp-bian)B-NH2 (7) has been isolated from the reaction of compound 1 with sodium in liquid ammonia. Borane (dpp-bian)B-H (8) can be prepared by the reactions of complexes 2 and 3 with LiAlH4. Diamagnetic compounds 2-8 have been characterized by IR, (1)H and (11)B NMR spectroscopy; paramagnetic complex 1 has been studied by the ESR method. Molecular structures of 2, 5, 7 and 8 have been determined by X-ray crystallography.

19.
Angew Chem Int Ed Engl ; 51(42): 10584-7, 2012 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-22991254

RESUMO

Redox isomerism is observed for a lanthanide complex for the first time. Upon lowering the temperature, an electron of [{(dpp-bian)Yb(µ-Cl)(dme)}(2)] (1) is transferred from the metal to the ligand (see picture), giving rise to marked shortening of Yb-N bonds and a hysteretic jump in the magnetic moment. The crystal packing is of a crucial importance, as two other crystal modifications of 1 do not undergo this effect.

20.
Chemistry ; 18(36): 11264-76, 2012 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-22847958

RESUMO

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). These addition reactions occur across Al-N-C moieties and result in the formation of new C-C and C-Al bonds. At elevated temperatures, compound 4 rearranges into complex 5, which consists of a radical-anionic dpp-bian ligand and two bridging alken-1,2-diyl moieties, (dpp-bian)Al(HCCPh)(2)Al(dpp-bian). This transformation is accompanied by cleavage of the dpp-bian-ligand-alkyne C-C bond, as well as of the Al-Al bond. In contrast to its analogous gallium complex, compound 1 is reactive towards internal alkynes. In the reaction of compound 1 with PhC≡CMe, besides symmetrical addition product [dpp-bian(R(1)R(2))]Al-Al[(R(2)R(1))dpp-bian] (R(1)=CMe, R(2)=CPh; 6), monoadduct [dpp-bian(R(1)R(2))]Al-Al(dpp-bian) (R(1)=CMe, R(2)=CPh; 7) was also isolated. Complexes 1-7 were characterized by IR, (1)H NMR (1-4), and electronic absorption spectroscopy (3-5); the molecular structures of compounds 1-7 were determined by single-crystal X-ray diffraction.


Assuntos
Acenaftenos/química , Alquinos/química , Alumínio/química , Amidas/química , Compostos Organometálicos/química , Cristalografia por Raios X , Ligantes , Modelos Moleculares , Estrutura Molecular , Compostos Organometálicos/síntese química , Oxirredução , Teoria Quântica
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