Synthesis, Structure and Characterization of Bis(ethylene-1,2-dithiolate)(μ_2-di-2-pyridyl-ketone p-phenyldiamine-N,N'''')-tin(IV) Dichloromethane

1 INTRODUCTION Sn(edt)2:[Sn(edt)2L]?CH2Cl2 through a one-pot reac- tion of Sn(edt)2, bis(2-pyridyl)ketone and p-phenyl- In recent years, the researches on tin sulfide mate- diamine in CH2Cl2. Herein we report the synthesis, rials draw increasing attention of chemists owning to crystal structure and characterization of the title com- their potential applications as photovoltaic materials, pound. holographic recording system[1, , solar control devi- 2] ces[3 and semiconductor materials. …     

Viscosalines B(1,2) and E(1,2): challenging new 3-alkyl pyridinium alkaloids from the marine sponge Haliclona viscosa

Four new 3-alkyl pyridinium alkaloids, the viscosalines?B(1) (1?a), B(2) (1?b), E(1) (2?a), and E(2) (2?b), were isolated from the Arctic sponge Haliclona viscosa. The structure elucidation of these isomeric compounds was challenging due to ambiguous fragments that derive during "standard" mass spectrometric fragmentation experiments. The final structure elucidation relied on the use of a combination of synthesis, liquid chromatography, and mass spectrometry. Three different mass spectrometers were used to differentiate between the synthetic structural isomers: a time-of-flight (TOF) mass spectrometer and two ion-trap mass spectrometers with different ion-transfer technologies (i.e., skimmer versus funnel optics). Although at first none of the spectrometers returned spectra that permitted structure elucidation, all three mass spectrometers provided analysis that successfully differentiated between the isomers after thorough method optimization. The use of in-source collision-induced dissociation (CID) with the ion trap and TOF instrument returned the most interesting results. The mode of fragmentation of the viscosalines under different experimental conditions is described herein. After successful optimization of the mass spectrometric method applied, the chromatographic method was improved to distinguish the previously inseparable isomers. Finally, both the liquid chromatography and mass spectrometric methods were applied to the natural products and the results compared to those from the synthetic compounds.     

Synthesis and spectroscopic studies of a new unsymmetrical ligand,N ( E ), N′ ( E )- bis [( E )-2-methyl-3-phenylallylidene]propane-1,2-diamine,and its zinc complexes

A new unsymmetrical bidentate Schiff base N(E),N′(E)-bis[(E)-2-methyl-3-phenylallylidene]-propane-1,2-diamine and four zinc complexes with general formula Zn(BMPAPD)X₂ in which X = Cl^?, Br^?, I^?, or SCN^?, have been prepared and characterized by elemental analysis, mass spectrometry, ¹H NMR (Nuclear Magnetic Resonance), ¹³C NMR, Fourier Transform–Infrared and Ultraviolet–Visible spectra, and molar conductance. All compounds are nonelectrolytes in dimethyformamide. The molar conductance and spectral properties indicate coordination of halides and thiocyanate ions to zinc in pseudo-tetrahedral geometry.     

Reactions of a 16-electron Cp*Co half-sandwich complex containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand with alkynones HC≡C-C(O)R (R = OMe, Me, Ph)

The reaction of the 16e half-sandwich complex Cp*Co(S₂C₂B₁₀H₁₀) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO₂Me, affords the 18e complexes 2–6. Compound 2 bears a B-CH₂ unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3–6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7–10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.     

Formation, structure, and reactivities of 1:1 adducts between quadricyclane and (η-cyclopentadienyl)(1,2-diphenyl- or -dimethoxycarbonyl-1,2-ethenedithiolato)rhodium(III)

The rhodiadithiolene complexes [Rh(Cp)(S₂C₂Z₂)] (Z=Ph (1a) and COOMe (1b)) reacted with quadricyclane (Q) to give 1:1 adducts [Rh(Cp)(S₂C₂Z₂) (C₇H₈)] (Z=Ph (2a) and COOMe (2b)) in which Rh and S of the complexes are bridged by C(7) (bridge carbons) and C(5) (edge carbons) of norbornene (C₇H₈), respectively. The structure of the adduct 2a was re-investigated and determined by X-ray structural analysis. The rhodiadithiolene complexes and those adducts showed the catalytic activities for the thermal isomerization from Q to norbornadiene (NBD). Adduct 2a photochemically dissociated to give the original complex 1a and NBD upon irradiation with a high-pressure mercury lamp. Skeletal rearrangements of the hydrocarbon moiety were confirmed in the formation of these adducts and in their photo-dissociation, according to deuterium labeling experiments.     

Synthesis and NMR Characterization of (Z,Z,Z,Z,E,E,ω)-Heptaprenol

We describe a practical, multigram synthesis of (2Z,6Z,10Z,14Z,18E,22E)-3,7,11,15,19,23,27-heptamethyl-2,6,10,14,18,22,26-octacosaheptaen-1-ol [(Z(4),E(2),ω)-heptaprenol, 4] using the nerol-derived sulfone 8 as the key intermediate. Sulfone 8 is prepared by the literature route and is converted in five additional steps (18% yield from 8) to (Z(4),E(2),ω)-heptaprenol 4. The use of Eu(hfc)(3) as an NMR shift reagent not only enabled confirmation of the structure and stereochemistry of 4, but further enabled the structural assignment to a major side product from a failed synthetic connection. The availability by this synthesis of (Z(4),E(2),ω)-heptaprenol 4 in gram quantities will enable preparative access to key reagents for the study of the biosynthesis of the bacterial cell envelope.     

Vibrational analysis of the S—trans conformation of (E,E), (Z,E) and (Z,Z)-2,4-hexadienes in the gaseous and solid states

The infrared (IR) spectra of liquid, gaseous and solid states as well as the liquid and solid phases Raman ones of the pure (Z,Z)-2, 4-hexadiene are recorded for the first time between 3100–50 cm⁻¹. Furthermore, the IR spectra of the gaseous and solid states and the solid Raman ones have been obtained (3100-50 cm⁻¹) for the (E,E) and (Z,E) isomers. A comparison between the present and our previous results for the liquid phase have enabled us to complete and confirm our previous assignment and to conclude that the planar s-trans conformation is prevailing in the three physical states under conditions used in this work.     

Facile Synthesis of (S,S)‐1,2‐Diacylamides and (S,S)‐1,2‐Diamines with C 2‐Symmetry

A series of chiral vicinal tertiary diacylamides with C ₂‐symmetry was synthesized from (S)‐α‐phenylethylamine, different aromatic aldehydes, and oxalyl chloride. The diacylamides obtained were then reduced to afford chiral vicinal diamines with C ₂‐symmetry. We propose that the diacylamides existed in four stable conformational isomers in solution because of the dihedral angle between acylamide bonds.     

Synthesis and Structural Studies of 2,2′-[(2E,5E)-hexane-2,5-diylidenedi-nitrilo]-dibenzenethiol and 2-Hydroxybenzaldehyde (2E,5E)-hexane-2,5-diylidenehydrazone ligands and their Mononuclear Cu(II) and Ni(II) Complexes

Monomeric copper(II) and nickel(II) complexes with tetradentate two new ligands, 2,2′-[(2E,5E)-hexane-2,5-diylidenedi- nitrilo]dibenzenethiol(H₂L) and 2-hydroxybenzaldehyde (2E,5E)-hexane-2,5-diylidenehydrazone(H₂L¹) have been synthesized and characterized by elemental analyses, magnetic moments, molar conductance, ¹H-NMR and ¹³C-NMR, IR, mass spectral studies, theoretical calculations (MM2 and AM1) molecular methods. The mononuclear metal complexes of H₂L and (H₂L¹) were found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of metal complexes indicated that the metal ions were coordinated to the sulphur (-SH) and/or (-OH) oxygen and imine nitrogen atoms (C = N). All of the data obtained from spectral, and molecular mechanics (MM2) or semi empirical calculations (AM1) studies support the structural properties of ligands and its Cu(II) and Ni(II) metal complexes.     

Synthesis,characterization, and biological activity studies on (E)-N′-[2-hydroxy-1,2-di(pyridin-2-yl)ethylidine]aroyl hydrazides and their copper(II) complexes

The reaction of copper(II) salts with (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene)aroyl hydrazide (H₂L¹, H₂L², H₃L³) or (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene) isonicotinohydrazide (H₂L⁴) afforded the complexes [(L)Cu(H₂O)₃], [(H₂L)Cu(OAc)(H₂O)], [(HL)Cu(OAc)] _n , [(H₂L)Cu(H₂O)](ClO₄)₂ and [(H₂L)Cu(OAc)(H₂O)], where n = 1 or 2 and L is the dinegative ion of the ligands. The ligands and their complexes are characterized by elemental analyses, spectral (IR, NMR, electronic, and ESR) and magnetic studies. The FT-IR indicates that the ligands are neutral or anionic polydentate. The number of the coordinating centers depends on the nature of the metal used and the reaction conditions. The room temperature magnetic moment values, electronic spectra and ESR data indicate square planar, trigonal bipyramidal, square pyramidal, and distorted octahedral ligand fields around copper(II). Thermal decomposition of the complexes was monitored by TG and DTG under N₂ and the thermal decomposition mechanisms are given. The compounds were screened for their antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligands are inactive against all studied bacteria. The complexes have variable activity with the most active [(H₂L)Cu(H₂O)](ClO₄)₂, where H₂L is H₂L¹ or H₂L². The minimum inhibition concentrations for these two complexes were determined. These biological activity results are related to the structures of the compounds.     

Niobium Bis- and Mono(Pentafulvene) Complexes: E−H Bond Cleavage and Insertion Reactions (E=C,N, O)

Bis(η⁵:η¹-(di-para-tolyl)pentafulvene)niobium chloride ( 1 ) reacts with methyl lithium via salt metathesis to the methylated bis(pentafulvene)niobium complex 2 , and with lithium 2,6-diisopropylanilide addition and subsequent N−H bond activation to the imido mono(pentafulvene)niobium complex 3 . Avoiding the competing protonation of the chloride, bis(pentafulvene)niobium complex 2 reacts with primary aromatic and aliphatic amines to form terminal niobocene imido complexes, and with water to form the analog terminal oxo complex. Secondary methyl amines undergo a simultaneous N−H and C−H activation to form niobaaziridines under mild conditions. In contrast to other reported examples, 3 can be employed to investigate the uncontested reactivity of mono(pentafulvene)niobium complexes. Reaction with 4-tert-butylphenol selectively yields a niobocene phenolate complex. Unprecedented for mono(pentafulvene)niobium complexes, treating 3 with multiple-bond-containing substrates (nitriles, isocyanates) smoothly results the insertion into the Nb-C_exo σ-bond, forming the corresponding alkylidene amido and imidato complexes.     

Triorganotin derivatives of 1,2-BIS(2′-carboxyphenylamino)-ethane and -propane,and ethylenediaminetetraacetic acid

Fifteen new complexes have been prepared of the type (R₃Sn)₂ L, where L is the dianion of 1,2-bis(2′-carboxyphenylamino)-ethane-and -propane, and ethylenediaminetetraacetic acid, and R is Me, n-Pr, n-Bu, Ph, or cyclohexyl (Cy). Characterisation by IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectroscopy indicates that the ligands are bound only through oxgen. In most cases the carboxylates are bidentate and the tin five-coordinate. The Ph₃Sn and Cy₃Sn derivatives contain tetrahedral tin, with monodentate carboxylates.     

Stabilities,Electronic Structures,and Bonding Properties of Iron Complexes (E1E2)Fe(CO)2(CNArTripp2)2 (E1E2=BF,CO, N2, CN−, or NO+)**

The coordination of 10-electron diatomic ligands (BF, CO N₂) to iron complexes Fe(CO)₂(CNAr^Tripp2)₂ [Ar^Tripp2=2,6-(2,4,6-(iso-propyl)₃C₆H₂)₂C₆H₃] have been realized in experiments very recently (Science, 2019 , 363, 1203–1205). Herein, the stability, electronic structures, and bonding properties of (E₁E₂)Fe-(CO)₂(CNAr^Tripp2)₂ (E₁E₂=BF, CO, N₂, CN⁻, NO⁺) were studied using density functional (DFT) calculations. The ground state of all those molecules is singlet and the calculated geometries are in excellent agreement with the experimental values. The natural bond orbital analysis revealed that Fe is negatively charged while E₁ possesses positive charges. By employing the energy decomposition analysis, the bonding nature of the E₂E₁–Fe(CO)₂(CNAr^Tripp2)₂ bond was disclosed to be the classic dative bond E₂E₁→Fe(CO)₂(CNAr^Tripp2)₂ rather than the electron-sharing double bond. More interestingly, the bonding strength between BF and Fe(CO)₂(CNAr^Tripp2)₂ is much stronger than that between CO (or N₂) and Fe(CO)₂(CNAr^Tripp2)₂, which is ascribed to the better σ-donation and π back-donations. However, the orbital interactions in CN⁻→Fe(CO)₂(CNAr^Tripp2)₂ and NO⁺→Fe(CO)₂(CNAr^Tripp2)₂ mainly come from σ-donation and π back-donation, respectively. The different contributions from σ donation and π donation for different ligands can be well explained by using the energy levels of E₁E₂ and Fe(CO)₂(CNAr^Tripp2)₂ fragments.     

M≡E and M=E Complexes of Iron and Cobalt that Emphasize Three-fold Symmetry (E = O, N, NR)

Mid-to-late transition metal complexes that feature terminal, multiply bonded ligands such as oxos, imides, and nitrides have been invoked as intermediates in several catalytic transformations of synthetic and biological significance. Until about ten years ago, isolable examples of such species were virtually unknown. Over the past decade or so, numerous chemically well-defined examples of such species have been discovered. In this context, the presentreview summarizes the development of 4- and 5-coordinate Fe(E) and Co(E) species under local three-fold symmetry.     

N,N′-(1,2-phenylene)bis­(pyridine-2-carboxamide) and N,N′-(1,2-cyclohexanediyl)bis(pyridine-2-carbox­amide) toluene hemisolvate

The crystal structures of N,N′-(1,2-phenyl­ene)­bis­(pyridine-2-carbox­amide), C₁₈H₁₄N₄O₂, (I), and N,N′-(1,2-cyclo­hexane­diyl)­bis­(pyridine-2-carbox­amide) have been determined, the latter compound as the toluene hemisolvate, C₁₈H₂₀N₄O₂·0.5C₇H₈, (II). In (I), the benzene ring is nearly coplanar with one of the pyridine rings and forms a dihedral angle of 59.4 (1)° with the other. However, in (II), the dihedral angle of the two pyridine rings is 70.0 (1)°.     

Unexpected fragmentation of phenyldithiobenzoate, formation and X-ray structure of [μ,η(S,S)-1,2-(dithio)-1,2-(diphenylethylene)] diiron hexacarbonyl complex

The reaction of Fe₂(CO)₉ with phenyldithiobenzoate PhCS₂Ph 1 afforded four colored compounds: [(μ-η³(C,S,S)PhCS₂Ph)]Fe₂(CO)₆2, (μ-S)₂Fe₃(CO)₉3, (μ-SPh)₂Fe₂(CO)₆4 and [μ-η²(S,S)][PhC(S)C(S)Ph]Fe₂(CO)₆5. Complex 5 was characterized by X-ray crystallography. The formation of complexes 4 and 5 was unexpected since it involved a fragmentation of the organic ligand 1 during its reaction with Fe₂(CO)₉. The electrochemical studies of 1, complexes 2 and 3 were undertaken in order to get information about the chemical behaviors of the intermediates generated by electron transfer. The results of cyclic voltammetry studies of 2 and 1 suggested that the reaction of 1 with Fe₂(CO)₉ involved two competitive reactions: (i) a thermal reaction which led to the expected compounds 2 and 3 and (ii) an electron transfer reaction involving a fragmentation of starting ligand 1 led to the unexpected complex 5. The required electrons may be provided by iron during the thermal decay of complexes 2 or 3 or Fe₂(CO)₉.     

Metal-induced B—H activation in Cp*Rh,Cp*Ir, (p-cymene)Ru,and (p-cymene)Os half-sandwich complexes containing the 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolato ligand

The reactivity of the 16e half-sandwich complexes Cp*Rh[E₂C₂(B₁₀H₁₀)] (1a,b), Cp*Ir[E₂C₂(B₁₀H₁₀)] (2a,b) (E = S (a), Se(b)), (p-cymene)Ru[S₂C₂(B₁₀H₁₀)] (3), (p-cymene)Os[S₂C₂(B₁₀H₁₀)] (4) (p-cymene = 1-Me-4-Prⁱ-benzene) towards various alkynes (acetylene, propyne, 3-methoxypropyne, methyl acetylenemonocarboxylate, dimethyl acetylenedicarboxylate, phenylacetylene, ferrocenylacetylene) was studied. The reactions start with an insertion into one of the M—E bonds, followed (except for MeO₂C—CC—CO₂Me) by intramolecular, metal-induced B—H activation, formation of an M—B bond, accompanied by simultaneous transfer of a hydrogen atom from boron via the metal atom to the alkyne. This leads to new complexes with a cisoidor transoid geometry (orientation of the E—C=C unit with respect to the C(1)—B bond). This geometry determines the course of further intramolecular reactions which lead selectively to carboranes mono- or disubstituted in B(3,6) positions. Numerous intermediates and final products were characterized by X-ray analysis in the solid state, and by multinuclear magnetic resonance in solution. First catalytic applications of 1a,b became evident by cyclotrimerization reactions.     

Synthesis of (E) α,2,4-Trinitrostilbenes from (E) 2,4-Dinitrostilbenes

Abstract

A convenient synthesis of (E) α,2,4-trinitrostilbenes 2a–d from (E) 2,4-dinitrostilbenes la–e by direct nitration is reported. Isomerization of the trans geometry of the reactant stilbenes to cis in the products was found. The structures of stilbenes 2a, 2c and 2d were confirmed by XRD.     

Synthesis and magnetic properties of copper(II)-cobalt(II) complexes ofN,N′-1,2-propanedisalicylamidatocuprate(II)

Summary The binuclear metal complexes [Cu(sampn)Co(L)₂] (L=bipy, phen), have been prepared by the reaction of sodiumN,N-1,2-propanedisalicylamidatocuprate(II) heptahydrate, Na₂[Cu(sampn)] 7H₂O, with a divalent metalion, and 2,2-bipyridine or 1, 10-phenathroline. The complexes were characterized by variable-temperature magnetic susceptibility measurements; the results indicate that a weak antiferromagnetic spin-exchange interaction operates between the metal ions.