A new synthetic route to optically active cyclomercurated ferrocenylimines

An adaptation of Kagan’s method for preparing 2-substituted ferrocenecarboxaldehydes has allowed us to directly prepare enantiopure (S_p)-2-chloromercurio-ferrocenecarboxaldehyde, (S_p)-3. Subsequent condensation of this aldehyde with (1R,2R)-(+)-1,2-diphenyl-1,2-ethanediamine ((R,R)-4) yielded a novel, enantiopure bis-cyclomercurated ferrocenylimine, (S_p,S_p,R_c,R_c)-N,N-bis(2-(chloromercurio)ferrocenylidene)-1,2-diphenylethane-1,2-diimine ((S_p,S_p,R_c,R_c)-5). In addition to the chiroptical data collected for both (S_p)-3 and (S_p,S_p,R_c,R_c)-5, the solid-state structure and absolute configuration of (S_p,S_p,R_c,R_c)-5 were confirmed by X-ray crystallography.     

Ruthenium complexes that incorporate a chiro-inositol derived diphosphinite ligand as catalysts for asymmetric hydrogenation reactions

The diol, 1d-1,2,5,6-tetra-O-methyl-chiro-inositol (D-9), can be conveniently prepared from 1d-chiro-inositol using a series of standard protection/deprotection steps. Treatment of D-9 with Ph₂PCl gives the chiral diphosphinite, 1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (D-10). The structure of D-10 has been determined by X-ray crystallography. Using 1l-chiro-inositol as starting material and following the same synthetic sequence used to produce D-10, the other enantiomer of this diphosphinite, 1l-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (L-10) can also be obtained. Ruthenium complexes of these diphosphinite ligands can be conveniently prepared through ligand substitution reactions with appropriate substrate complexes. Thus, treatment of [RuCl₂(COD)]_n with D-10 in the presence of triethylamine produces the bis(diphosphinite) complex, RuHCl{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}₂ (11). In addition, reaction between RuCl₂(PPh₃)₃, D-10 and (1R,2R)-(+)-1,2-diphenylethylenediamine gives the mono(diphosphinite) complex, RuCl₂{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}{κ²(N,N)-(1R,2R)-(+)-1,2-diphenylethylenediamine} (12). The closely related complex RuCl₂{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}{κ²(N,N)-(1S,2S)-(−)-1,2-diphenylethylenediamine} (13) can be obtained in a similar manner using (1S,2S)-(−)-1,2-diphenylethylenediamine in place of the corresponding (+)-isomer. These new chiral, diphosphinite complexes catalyse the hydrogenation of the ketones acetophenone and 3-quinuclidinone to give the corresponding alcohols with low to moderate enantiomeric excesses. The complexes are not catalytically active for the hydrogenation of the olefin dimethylitaconate or the α-ketoester methyl benzoylformate.     

Reactions of bis(tetrazole)phenylenes. Surprising formation of vinyl compounds from alkyl halides

The reactions of 1,2-bis(tetrazol-5-yl)benzene (1), 1,3-bis(tetrazol-5-yl)benzene (2), 1,4-bis(tetrazol-5-yl)benzene (3), 1,2-(Bu₃SnN₄C)₂C₆H₄ (4), 1,3-(Bu₃SnN₄C)₂C₆H₄ (5) and 1,4-(Bu₃SnN₄C)₂C₆H₄ (6) with 1,2-dibromoethane were carried out by two different methods in order to synthesise pendant alkyl halide derivatives of the parent bis-tetrazoles. This lead to the formation of several alkyl halide derivatives, substituted at either N1 or N2 on the tetrazole ring, as well as the surprising formation of several vinyl derivatives. The crystal structures of both 1,2-[(2-vinyl)tetrazol-5-yl)]benzene (1-N,2-N′) (1b) and 1,3-bis[(2-bromoethyl)tetrazol-5-yl]benzene (2-N,2-N′) (5d) are discussed.     

Ruthenium-catalysed asymmetric transfer hydrogenation of para-substituted α-fluoroacetophenones

The first examples of asymmetric transfer hydrogenation of α-fluoroacetophenones are reported. Eight para-substituted α-fluoroacetophenones have been reduced using four catalytic systems constructed of [RuCl₂(p-cymene)₂]₂ or [RuCl₂(mesitylene)₂]₂ in combinations with each of the ligands (1R,2R)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine ((R,R)-TsDPEN) and (1R,2R)-N-(p-toluenesulfonyl)-1,2-cyclohexanediamine ((R,R)-TsCYDN). All reactions were performed in both water and formic acid/triethylamine. The highest enantioselectivity was obtained using the (R,R)-TsDPEN ligand in a formic acid/triethylamine mixture, giving the (S)-1-aryl-2-fluoroethanols in high to moderate enantiomeric excess (97.5-84.5%). For this solvent system the presence of electron withdrawing groups in the para position reduced the enantioselectivity. Reactions performed in water generally gave lower enantioselectivity and reaction rate, although RuCl(mesitylene)-(R,R)-TsDPEN yielded the product alcohols with enantiomeric excess in the range of 95.5-76.5%.     

Selective synthesis of bis[1,2]dithiolo[1,4]thiazines from 4-isopropylamino-5-chloro-1,2-dithiole-3-ones

Reaction of 4-isopropylamino-5-chloro-1,2-dithiole-3-ones 3 and S₂Cl₂ in acetonitrile gave selectively 3-oxo-bis[1,2]dithiolo[1,4]thiazine-5-thiones 1 by the addition of triethylamine and bis[1,2]dithiolo[1,4]thiazine-3,5-diones 5 under the action of formic acid. 3,5-Diones 5 were also obtained by intramolecular cyclization of N,N-bis(5-chloro-3-oxo[1,2]dithiol-4-yl)amines 6 with S₂Cl₂ in the presence of Et₃N.     

Chiral dioxovanadium(V) Schiff base complexes of 1,2-diphenyl-1,2-diaminoethane and aromatic o-hydroxyaldehydes: Synthesis,characterization, catalytic properties and structure

A series of dioxovanadium(V) complexes of tridentate ligands obtained by monocondensation of chiral 1,2-diphenyl-1,2-diaminoethane and aromatic o-hydroxyaldehydes was synthesized. The complexes were characterized by spectroscopic methods in the solid state (IR) and in solution (UV–Vis, CD, ¹H and ⁵¹V NMR). Single crystal X-ray analysis was performed with (VO₂L · H₂O)₂, denoted as (4 · H₂O)₂, where L is (S,S)-1-amino-2-{(2′-oxido-4′,6′-dimethoxyphenyl)methylene}amino-1,2-diphenylethane. Crystal structure analysis revealed that (4 · H₂O)₂ contains oxo-bridged dimers of 4 joined with water molecules by hydrogen bonding interactions, and that two five-membered chelate rings in the dimeric molecule adopt different envelope conformations, one on the asymmetric carbon atom linked to the azomethine nitrogen and the other on the asymmetric carbon atom linked to the primary amino nitrogen. The (S,S)- and (R,R)-complexes bearing the methoxy substituent in positions 3 or 5 of the salicylidene moiety catalyze the oxidation of phenyl methyl sulfide by cumene hydroperoxide yielding the corresponding sulfoxide almost quantitatively with 34–39% enantiomeric excess.     

rac-Lactide polymerization using aluminum complexes bearing tetradentate phenoxy-amine ligands

A family of aluminum-methyl complexes supported by tetradentate phenoxy-amine ligands has been prepared and employed in the ring-opening polymerization of rac-lactide; the ligands include N,N-bis(3,5-dimethyl-2-hydroxybenyl)-N′,N′-dimethyl-1,2-diaminoethane (L¹), N,N-bis(3,5-diisopropyl-2-hydroxybenyl)-N′,N′-dimethyl-1,2-diaminoethane (L²) and N,N-bis(3,5-dichloro-2-hydroxybenyl)-N′,N′-dimethyl-1,2-diaminoethane (L³). Polymerizations of rac-lactide were carried out by treatment of the aluminum-methyl complexes with PhCH₂OH and rac-lactide at 70 °C, affording well-controlled formation of polylactide (PLA) and a moderate isotactic bias for initiators bearing L¹ and L²; the chloro-substituted ligand L³ afforded largely atactic PLA.     

Synthesis, structure, and catalytic activity of titanium(IV) and zirconium(IV) amides with chiral biphenyldiamine-based ligands

A new series of titanium(IV) and zirconium(IV) amides have been prepared from the reaction between M(NMe₂)₄ (M = Ti, Zr) and C₂-symmetric ligands, (R)-2,2′-bis(pyridin-2-ylmethylamino)-6,6′-dimethyl-1,1′-biphenyl (2H₂), (R)-2,2′-bis(pyrrol-2-ylmethyleneamino)-6,6′-dimethyl-1,1′-biphenyl (3H₂), (R)-2,2′-bis(diphenylphosphinoylamino)-6,6′-dimethyl-1,1′-biphenyl (4H₂), (R)-2,2′-bis(methanesulphonylamino)-6,6′-dimethyl-1,1′-biphenyl (5H₂), (R)-2,2′-bis(p-toluenesulphonylamino)-6,6′-dimethyl-1,1′-biphenyl (6H₂), and C₁-symmetric ligands, (R)-2-(diphenylthiophosphoramino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (7H) and (R)-2-(pyridin-2-ylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (8H), which are derived from (R)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl. Treatment of M(NMe₂)₄ with 1 equiv. of N₄-ligand, 2H₂ or 3H₂ gives, after recrystallization from an n-hexane solution, the chiral zirconium amides (2)Zr(NMe₂)₂ (9), (3)Zr(NMe₂)₂ (11), and titanium amide (3)Ti(NMe₂)₂ (10), respectively, in good yields. Reaction of Zr(NMe₂)₄ with 1 equiv of diphenylphosphoramide 4H₂ affords the chiral zirconium amide (4)Zr(NMe₂)₂ (12) in 85% yield. Under similar reaction conditions, treatment of Ti(NMe₂)₄ with 1 equiv. of sulphonylamide ligand, 5H₂ or 6H₂ gives, after recrystallization from a toluene solution, the chiral titanium amides (5)Ti(NMe₂)₂·0.5C₇H₈ (13·0.5C₇H₈) and (6)Ti(NMe₂)₂ (15), respectively, in good yields, while reaction of Zr(NMe₂)₄ with 1 equiv. of 5H₂ or 6H₂ gives the bis-ligated complexes, (5)₂Zr (14) and (6)₂Zr (16). Treatment of M(NMe₂)₄ with 2 equiv. of diphenylthiophosphoramide ligand 7H or N₃-ligand 8H gives, after recrystallization from a benzene solution, the bis-ligated chiral zirconium amides (7)₂Zr(NMe₂)₂ (17) and (8)₂Zr(NMe₂)₂ (19), and bis-ligated chiral titanium amide (8)₂Ti(NMe₂)₂ (18), respectively, in good yields. All new compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 10, 12, 13, and 17-19 have further been confirmed by X-ray diffraction analyses. The zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good to excellent yields with moderate ee values, while the titanium amides are not.     

Substitution of ligands in dichloro-2-(arylazo)heterocyclepalladium(II) by 8-quinolinol: kinetics and mechanistic studies

Nucleophilic substitutions of Pd(N,N)Cl₂[(N,N = 1-methyl-2-(arylazo)imidazole (RaaiMe), p-RC₆H₄N=NC₃H₂NN-1-Me; 2-(arylazo)pyridine (Raap), p-RC₆H₄N=NC₅H₄N; 2-(arylazo)pyrimidine (Raapm), p-RC₆H₄N=NC₄H₃N₂ where R = H (a), Me (b), Cl (c)] with 8-quinolinol (HQ) have been examined by spectrophotometry at 298 K in MeCN solution. The product, Pd(Q)₂, has also been confirmed by independent synthesis from Na₂[PdCl₄] and HQ in EtOH. The kinetics of the reaction have been studied under pseudo-first-order conditions and the analyses support a nucleophilic association path. A single phase reaction has been observed and follows the rate law, rate = a + k [Pd(N,N)Cl₂] [HQ]². Thus, the reaction is first order in [Pd(N,N)Cl₂] and second order in [HQ]. External addition of Cl^–(LiCl) suppresses the rate. The rate increases as follows: Pd(RaaiMe)Cl₂ < Pd(Raap)Cl₂ < Pd(Raapm)Cl₂.     

Synthesis and crystal structure of two new heteropolynuclear [NiCdCdNi] and [NiCdNi] Schiff base complexes involving bridging chlorine and oxygen functions

Two new heteropolynuclear Schiff base complexes, [Ni₂Cd₂L₂Cl₂(μ-Cl)₂] (1) and [Ni₂CdL′₂Cl(H₂O)]ClO₄·H₂O (2) where L = [N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine and L′ = [N,N′-bis(2-hydroxypropiophenylidene)]propane-1,2-diamine, have been synthesized by refluxing equimolar amounts of nickel perchlorate, cadmium chloride and the respective tetradentate Schiff base ligand, H₂L or H₂L′ in methanol medium. The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies on 1 reveal the presence of a bis(heterodinuclear) [Ni^IICd^II]₂ unit in which the two central cadmium ions are doubly chloro-bridged with each other and each of them is connected to a nickel(II) center through two phenolate oxygen bridges. In contrast, complex 2 contains a heterotrinuclear [Ni^IICd^IINi^II] unit in which the central cadmium ion is connected to two nickel(II) centers through two doubly bridging phenolate oxygen atoms. The Cd(II) ions in 1 and 2 adopt distorted, square pyramidal (CdO₂Cl₃) and octahedral (CdO₅Cl) geometries respectively. On the other hand, the Ni(II) ions in both 1 and 2 assume the same coordination geometry, i.e. a distorted square planar (NiO₂N₂) arrangement. Intermolecular C-H?Cl or O-H?Cl and O-H?O hydrogen bonding interactions are operative in the complexes to build up 2D supramolecular structures in their solid states.     

Salen and half-salen palladium(II) complexes: synthesis, characteriztion and catalytic activity toward Suzuki-Miyaura reaction

Salen and half-salen palladium(II) complexes (salden)Pd (1, salden=N,N′-bis(3,5-di- tert-butylsalicylidene)-1,2-dimethylethylenediamine), (hsalph)PdCl (2, hsalph=3,5-di-tert- butylsalicylidene-1-iminophenylene-2-amine), and (salph)Pd (4, salph=N,N′-bis(3,5-di-tert- butylsalicylidene)-1,2-phenylenediamine) were prepared and structurally characterized by X-ray crystallography. Complex 2 proved to exhibit high catalytic activity toward Suzuki-Miyaura reaction. Polyaromatic C₃-symmetric derivatives and various fluorinated biphenyl derivatives were readily achieved in good yields using Suzuki-Miyaura reaction catalyzed by complex 2.     

Synthesis, X-ray crystal structure and cytotoxicity of a new tetranuclear ruthenium arene complex

The tetranuclear ruthenium arene compound [(cym)₄Ru₄(2)Cl₆]Cl₂ (3) (cym = η⁶-p-cymene, 2 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane) was prepared and characterised by one- and two-dimensional NMR techniques. Its cytotoxicity against four different cell lines was determined and, with an approximate IC₅₀ of >100 μM 3 can be regarded as non-toxic. Its partition coefficient in n-octanol/water (log D_7.4) was also determined. The structures of complex 3 as well as of the related compound [(cym)₂Ru₂(4)Cl₂]Cl₂ (5) (4 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane dioxide) were determined by single crystal structure analysis. Upon oxidation in protic solvents, ligand 2 shows P-C bond cleavage reactions to yield P,P′-bis(N-methylimidazol-2-yl)ethylene diphosphinic acid (6).     

Synthesis, crystal structure and antibacterial activity of a group of mononuclear manganese(II) Schiff base complexes

Five mononuclear complexes of manganese(II) of a group of the general formula, [MnL(NCS)₂] where the Schiff base L = N,N′-bis[(pyridin-2-yl)ethylidene]ethane-1,2-diamine (L¹), (1); N,N′-bis[(pyridin-2-yl)benzylidene]ethane-1,2-diamine (L²), (2); N,N′-bis[(pyridin-2-yl)methylidene]propane-1,2-diamine (L³), (3); N,N′-bis[(pyridin-2-yl)ethylidene]propane-1,2-diamine (L⁴), (4) and N,N′-bis[(pyridin-2-yl)benzylidene]propane-1,2-diamine (L⁵), (5) have been prepared. The syntheses have been achieved by reacting manganese chloride with the corresponding tetradentate Schiff bases in presence of thiocyanate in the molar ratio of 1:1:2. The complexes have been characterized by IR spectroscopy, elemental analysis and other physicochemical studies, including crystal structure determination of 1, 2 and 4. Structural studies reveal that the complexes 1, 2 and 4 adopt highly distorted octahedral geometry. The antibacterial activity of all the complexes and their respective Schiff bases has been tested against Gram(+) and Gram(−) bacteria.     

New active ruthenium(II) complexes based N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester ligands for transfer hydrogenation of aromatic ketones by propan-2-ol

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine, 1 and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester, 2 ligands to afford bridged dinuclear complexes [C₁₀H₆N₂{NHPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 3 and [C₁₀H₆N₂{OPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 4 in quantitative yields. These bis(aminophosphine) and bis(phosphinite) based Ru(II) complexes serve as active catalyst precursors for the transfer hydrogenation of acetophenone derivatives in 2-propanol and especially 4 acts as a good catalyst, giving the corresponding alcohols in 99% yield in 20 min (TOF ? 280 h⁻¹).     

Effective reduction of <Emphasis Type="Italic">p</Emphasis>-nitrophenol catalyzed by nickel(II) adamantane complexes

Two Ni(II) adamantane complexes, [Ni(bqad)Cl₂] (1) and [Ni(bpad)(dmbp)(H₂O)](ClO₄)₂·CH₃OH H₂O (2) (bqad = N,N′-bis(2-quinolinylmethyl) amantadine, bpad = N,N′-bis(2-pyridylmethyl)amantadine, dmbp = 5,5′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, infrared spectroscopy and single crystal X-ray diffraction. The nickel centers in complex 1 have a distorted tetragonal pyramidal geometry, while the coordination polyhedron of 2 can be described as a distorted octahedron. The reaction kinetics for reduction of p-nitrophenol to p-aminophenol catalyzed by these complexes has been investigated by UV–visible spectrophotometry. Complex 1 exhibits a higher turnover frequency of 1.4 min^?1 for the reduction of p-nitrophenol.     

Synthesis, characterization, and spectrophotometric studies of novel fluorescent arachno decaborane and nonaborane clusters containing aza-distyrylbenzene derivatives

Two aza-analogues of distyrylbenzene namely: 1,4-bis[β-(4-quinolyl)vinyl]benzene (PhQ) and 1,4-bis[β-(4-pyridyl)vinyl]benzene (PhPy) containing arachno-decaborane or arachno-nonaborane clusters have been isolated: 6,9-(PhQ)₂-arachno-B₁₀H₁₂ (1), N,N′-bis[9-Me₂S-arachno-B₁₀H₁₂-6-yl]PhQ (2), 6,9-(PhPy)₂-arachno-B₁₀H₁₂ (3), N,N′-bis[(9-Me₂S)-arachno-B₁₀H₁₂-6-yl]PhPy (4), N,N′-bis[arachno-B₉H₁₃-4-yl]PhQ (5), 4-PhQ-arachno-B₉H₁₃ (6), N,N′-bis[arachno-B₉H₁₃-4-yl]PhPy (7), and 4-PhPy-arachno-B₉H₁₃ (8). These boronated compounds were easily prepared from the displacement reactions of weaker ligand (SMe₂) of bis (dimethyl sulfide) arachno-decaborane(14) {6,9-(Me)₂SB₁₀H₁₂}or dimethyl sulfide-arachno-nonaborane {4-(Me)₂SB₉H₁₃} by the stronger bidentate ligands of PhQ or PhPy in ratio (1:2). The electronic interaction between decaborane or nonaborane arachno-type unit and the bonded pyridine units has been investigated by UV-Vis spectroscopy and by AM1 molecular orbital calculations. The resulting compounds undergo trans-cis photoisomerization upon excitation. The connection of boron clusters to PhQ and PhPy led to enhancing of the photoreactivity and decreasing of the fluorescence quantum yield of the products.     

Polymer chlorobismuthate complex catena-{((Me,Me)Bpe)[BiCl5]} n : Synthesis and crystal structure

The reaction of BiCl₃ and N,N-dimethyl-1,2-bis(pyridyl)ethane chloride (Me,Me-Bpe) in 2 M HCl affords a polymer chlorobismuthate complex {((Me,Me)Bpe)[BiCl₅]} _n (I). The structure of complex I is determined by X-ray diffraction analysis (CIF file CCDC 1058842). The anionic moiety of the complex is presented by a 1D coordination polymer ([BiCl₅]^2n–) _n consisting of octahedral blocks {Cl₆} linked by µ₂- bridging chloride ligands into infinite zigzag chains.     

Gas-phase pyrolysis of benzimidazole derivatives: novel route to condensed heterocycles

Gas-phase pyrolysis of N-(1H-benzimidazol-2-yl)-N′-arylidenehydrazines 1a-e gave the corresponding arylnitriles 2a-e, 2-aminobenzimidazole 3, 2,4,5-triphenylimidazole 4, 1,3-diphenyl-8H-2,3a,8-triazacyclopenta[a]indene 5, and 5,11-diphenyl-6H,12H-dibenzimidazo[1,2-a];1’,2’-d]pyrazine 6. The kinetics and analysis of the products of reaction are reported and used to elucidate the mechanism of the elimination process.     

Uranyl(VI) complexes of [O,N,O,N′]-type diaminobis(phenolate) ligands: Syntheses,structures and extraction studies

The syntheses and crystal structures of four new uranyl complexes with [O,N,O,N′]-type ligands are described. The reaction between uranyl nitrate hexahydrate and the phenolic ligand [(N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-N′,N′-dimethylethylenediamine)], H₂L1 in a 1:2 molar ratio (M to L), yields a uranyl complex with the formula [UO₂(HL1)(NO₃)] · CH₃CN (1). In the presence of a base (triethylamine, one mole per ligand mole) with the same molar ratio, the uranyl complex [UO₂(HL1)₂] (2) is formed. The reaction between uranyl nitrate hexahydrate and the ligand [(N,N-bis(2-hydroxy-3,5-di-t-butylbenzyl)-N′,N′-dimethylethylenediamine)], H₂L2, yields a uranyl complex with the formula [UO₂(HL2)(NO₃)] · 2CH₃CN (3) and the ligand [N-(2-pyridylmethyl)-N,N-bis(2-hydroxy-3,5-dimethylbenzyl)amine], H₂L3, in the presence of a base yields a uranyl complex with the formula [UO₂(HL3)₂] · 2CH₃CN (4). The molecular structures of 1–4 were verified by X-ray crystallography. The complexes 1–4 are zwitter ions with a neutral net charge. Compounds 1 and 3 are rare neutral mononuclear [UO₂(HLn)(NO₃)] complexes with the nitrate bonded in η²-fashion to the uranyl ion. Furthermore, the ability of the ligands H₂L1–H₂L4 to extract the uranyl ion from water to dichloromethane, and the selectivity of extraction with ligands H₂L1, H₃L5 (N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-3-amino-1-propanol), H₂L6 · HCl (N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-1-aminobutane · HCl) and H₃L7 · HCl (N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-6-amino-1-hexanol · HCl) under varied chemical conditions were studied. As a result, the most efficient and selective ligand for uranyl ion extraction proved to be H₃L7 · HCl.