Transition metal complexes of 2-amino-3-chloro-5-trifluoromethylpyridine: syntheses,structures, and magnetic properties of [(TMCAPH)2CuBr4] and [(TMCAPH)2CuCl4]

The reaction of CuX₂ (X = Br or Cl) with 2-amino-3-chloro-5-trifluoromethylpyridine in aqueous acids (HX; X = Br or Cl) yields bis(2-amino-3-chloro-5-trifluoromethylpyridinium)tetrabromocuprate(II) (1) and bis(2-amino-3-chloro-5-trifluoromethylpyridinium)tetrachlorocuprate(II) (2). These compounds have been characterized by IR, powder X-ray diffraction (XRD), single crystal XRD, combustion analysis, and temperature-dependent magnetic susceptibility. Compound 1 crystallizes in the monoclinic space group P2₁/c with three ions in the asymmetric unit, whereas 2 crystallizes in the triclinic space group P 1, and the asymmetric unit contains 18 ionic moieties. Both compounds exhibit antiferromagnetic exchange via the double halide exchange pathway and singlet ground states, with stronger exchange observed for 1. Both compounds exhibit multiple potential magnetic exchange pathways, but fitting of the data to available analytical models suggests that the magnetic exchange constants 2J/k _B are ～50 K in 1 and ～6 K in 2, respectively.     

Synthesis and Characterization of Alkyltris(2-pyridyl)phosphonium Salts

Alkytris(2-pyridyl)phosphonium salts [(2-Py) ₃ PR]X 1 [1a, R = Et, X = Br; 1b, R = Pr, X = Br; 1c, R = Bu, X = Br; 1d, R = CH₂Ph, X = Br; 1e, R = CH ₂ Ph, X = Cl] were synthesised from (2-Py) ₃ P and an excess of RCl. 1c and 1e were found to rapidly decompose in hot acetone to 2,2′-bipyridinium(+1) bromide 2 and (2-Py)P(O)(CH ₂ Ph)C(OH)Me ₂ 3, respectively. A reaction mechanism for both products is proposed. All compounds were fully characterized, including X-ray crystallography for 1a and 3 with 1a being the first representative of this class of compounds characterized by this technique.     

Transition Metal Halide Salts and Complexes of 2-Aminopyrimidine: Cobalt(II) and Nickel(II) compounds,Crystal Structures of Bis(2-Aminopyrimidinium)MX4 [M = Co,Ni; X = Cl,Br] and 2-Aminopyrimidinium(+2) [NiBr2(H2O)4]Br2

The reaction of MX₂ (M = Co(II), Ni(II); X = Cl, Br) with 2-aminopyrimidine in aqueous acid yields compounds [(2-apmH)₂MX₄], (2-apmH)₂[MX₄], or (2-apmH₂) [MX₂(H₂O)₄]X₂ (2-apmH = 2-aminopyrimidinium; 2-apmH₂ = 2-aminopyrimidinium(2+)). All compounds have been characterized by single crystal X-ray diffraction. The compounds [(2-apmH)₂MX₄] with M = Co, X = Cl (1); M = Ni, X = Cl (3); and M = Ni, X = Br (4) are isomorphous and crystallize as nearly square planar MX₄ units with the 2-apmH cations coordinated in the axial sites through the unprotonated ring nitrogen. (2-ApmH)₂[CoBr₄] (2) crystallizes as the salt with a nearly tetrahedral CuBr₄ ^2- anion. (2-ApmH₂)[NiBr₂(H₂O)₄]Br₂ (5) forms as a cocrystal of the neutral, six-coordinate nickel complex and (2-ampH₂)Br₂, stabilized by extensive hydrogen bonding. Crystal data (1): monoclinic, P2₁/c, a = 7.540(4), b = 12.954(4), c = 7.277(3) Å, β = 110.09(6), V = 667.4(5) ų, Z = 2, D_calc = 1.955 Mg/m³, μ = 2.079 mm^-1, R = 0.0501 for [|I|≥2(I)]. For (2): triclinic, P-1, a = 7.720(2), b = 7.916(2), c = 14.797(3) Å, α = 97.264(3), β = 104.788(3), γ = 105.171(3)°, V = 825.3(3) ų, Z = 2, D_calc = 2.296 Mg/m³, μ = 10.715 mm^-1, R = 0.0308 for [|I|≥2(I)]. For (3): monoclinic, P2₁/c, a = 7.595(3), b = 12.891(4), c = 7.204(3) Å, β = 111.07(3)°, V = 658.2 ų, Z = 2, D_calc = 1.982 Mg/m³, μ = 2.279 mm^-1, R = 0.0552 for [|I|≥2(I)]. For (4): monoclinic, P2₁/c, a = 7.840(2), b = 13.358(4), c = 7.518(2) Å, β = 110.923(3)°, V = 938.6(3) ų, Z = 2, D_calc = 2.577 Mg/m³, μ = 12.18 mm^-1, R = 0.0280 for [|I|≥2(I)]. For (5): orthorhombic, Pnma, a = 16.776(6), b = 11.943(4), c = 7.079(3) Å, V = 1418.2(9) ų, Z = 4, D_calc = 2.564 Mg/m³, μ = 12.639 mm^-1, R = 0.0381 for [|I|≥2σ(I)].     

Transition Metal Halide Salts of 1,3-bis(4-Pyridyl)propane: Synthesis and Structural Characterization

The resulting salts of (H₂bpp)MX₄ · n H₂O (M = Zn, X = Cl, n = 1, 1; M = Cd, X = Br, n = 0, 2; M = Hg, X = Cl, n = 1, 3; M = Cu, X = Cl, n = 0, 4; M = Cu, X = Br, n = 1, 5; M = Pt, X = Cl, n = 1, 6) were crystallized from the reaction mixture prepared by adding MX₂ to the HX solution of 1,3-bis(4-pyridyl)propane (bpp), while the salt of colorless (H₂bpp)SnCl₆, 7, was crystallized from the reaction mixture prepared by adding SnCl₂ to the HCl solution of bpp. Their structures have been determined by X-ray crystallography. All the compounds show supramolecular structures in the solid state by intermolecular hydrogen bondings and aromatic – interactions. The H₂bpp²⁺ cations in these metal salts adopt the gauche–gauche and anti–anti conformations with different dihedral angles for the two pyridyl rings.     

SYNTHESIS OF ORGANOTRANSITION METAL COMPLEXES CONTAINING p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENYL AND p-METHOXYCARBONYLPHENYL (HYDROXYMETHYL)CYCLOPENTADIENYL LIGANDS FROM SODIUM p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENIDE. X-RAY STRUCTURE OF η5-p-MeO2CC6H4COC5H4Mo(CO)3I

Abstract

A new functionally substituted cyclopentadienyl salt p-MeO₂CC₆H₄COC₅H₄Na (1) was prepared from cyclopentadienylsodium and dimethyl terephthalate in THF, and which might be utilized to synthesize a series of novel transition metal complexes containing difunctional group-substituted cyclopentadienyl ligands; 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with PBr₃ or I₂ to give mononuclear organomolybdenum (or tungsten) halides η⁵-p-MeO₂CC₆H₄COC₅H₄M(CO)3X(2, M = Mo, X = Br; 3, M = W, X = Br; 4, M = Mo, X = I; 5, M = W, X = I), whereas reaction of 1 with W(CO)₆ and successive treatment with selenium powder and MeI or PhCH₂Cl afforded mononuclear organotungsten selenolate complexes η⁵-p-MeO₂CC₆H₄COC₅H₄W (CO)₃SeMe (6) and η⁵-p-MeO₂CC₆H₄COC₅H₄W(CO)₃SeCH₂Ph (7). In addition, 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with FeCo₂(CO)₉(μ₃-S) to produce the corresponding polynuclear complexes η⁵-p-MeO₂CC₆H₄COC₅H₄MFeCo(CO)₈(μ₃?S) (8, M = Mo; 9, M = W), which could be converted with NaBH₄ into hydroxyl derivatives η⁵-p-MeO₂CC₆H₄CH(OH)C₅H₄MFeCo(CO)₈(μ₃?S) (10, M = Mo; 11, M = W). All the new transition metal complexes 2–11 have been fully characterized by elemental analysis, IR and ¹H NMR spectroscopy, as well as for 4 by an X-ray diffraction analysis.     

Synthesis of 1-triphenylgermylpropiono-4-substituted semicarbazides,thiosemicarbazides and their heterocyclic derivatives

Twenty-one new organogermanium compounds with the formulae Ph₃GeCHR¹CH₂CONHNHC(X)NHR² (1) (R¹=H, Ph; = Ph, p-CH₃Ph, O -CH₃Ph, p-ClPh, COPh, X = S, O) and (R¹ = H, Ph; R² = Ph, p-CH₃Ph, o-CH₃Ph, p-ClPh; X=S, O) were synthesized and characterized by elemental analysis, ¹H NMR, IR, MS and X-ray diffraction techniques. Compounds l were prepared by the reactions of Ph₃GeCHR¹CH₂CONHNH₂ with R²NCX in chloroform in 77-94% yields, and 2 were obtained by refluxing l with sodium hydroxide (8%) with yields of 55-94%.     

INORGANIC RINGS WITH GALLIUM ORGANYLS AND IMINODIPHOSPHINECHALCHOGENIDES

The organometallic complexes of general formula [Me ₂ Ga{(XPR ₂ ) (YPR′ ₂ )N}] (R, R′ = Ph, X, Y = O, (1); R, R′ = Ph, X, Y = S (2); R, R′ = Ph, X = O, Y = S (3); R = Me, R′ = Ph, X = O, Y = S (4)) were obtained by alkane eliminations from Me ₃ Ga and the free acidic ligands, LH, in toluene solutions. Complexes 1– 4 seem to be potential precursors to cationic gallium species.     

Perfluormethyl-Element-Liganden. XL. Chrom- und Wolframpentacarbonylkomplexe von Bis(trifluormethyl)phosphanen des Typs (F3C)2PX′ (X′ = H,F, Cl,Br, I,NEt2)

Perfluormethyl-Element-Ligands. XL. Chromium and Tungsten Pentacarbonyl Complexes of Bis(trifluoromethyl)phosphanes of the Type (F₃C)₂PX′ (X′ = H, F, Cl, Br, I, NEt₂) The complexes M(CO)₅P(CF₃)₂X′ (M = Cr, W; X′ = H, F, Cl, Br, I) are obtained in preparative amounts (yields between 15 and 42%) by reacting the ligands (F₃C)₂PX′ with the adducts “M(CO)₅CH₂Cl₂”, photochemically generated from M(CO)₆ in methylene chloride. The corresponding derivatives of the aminophosphane Et₂NP(CF₃)₂ can be produced in good yields (60–75%) using the THF complexes M(CO)₅THF as precursors. The spectroscopic data (MS, IR, NMR) of the new compounds are reported. The CO valence frequencies v(CO) and the coordination shifts Δδ prove the high π-acidity of the ligands (F₃C)₂PX′.     

Transition metal complexes of the 1,2-dihapto-4-cyano-5-amino-pyrazolide ion

Summary Reaction of 4-cyano-5-aminopyrazole, Hcpz, with ammoniacal solutions of metal(I) chlorides yields colorless and insoluble polymeric complexes, [Mcpz]_n [where M=Cu(1) or Ag(2)]. However, pyrazolidebridged dimeric species [M(PPh₃)₂cpz]₂ (3) or(4), soluble in most non-polar solvents, were obtained from the precursor [M(PPh₃)₃X] (X=Cl or NO₃) under similar reaction conditions. The compounds have been characterized using physico-chemical methods and are diamagnetic.     

Synthesis,structure and properties of complex compounds of cobalt,nickel, copper and zinc with 2-formylpyridine semicarbazone

2-Formylpyridine semicarbazone L reacts with cobalt, nickel, copper and zinc chlorides, nitrates and perchlorites to form coordination compounds of compositions ML₂X₂·nH₂O (M=Co, Ni, Cu, Zn; X = Cl, NO₃, ClO₄; L = NC₅H₄-CH=N-NH-C(O)-NH₂; n = 0, 1) and CuLX₂·nH₂O (X = Cl, Br, NO₃; n = 0−0.5). Complex CuL(NO₃)₂ has polynuclear, CuLX₂·0.5H₂O (X = Cl, Br), binuclear, and other compounds, mononuclear structures. Azomethine L behaves in them as tridental N,N,O-ligand. Thermolysis of these complexes proceeds through such stages as dehydration (80–95°C), deactivation (145–155°C) and complete theral degradation (170–590°C). Complexes CuLX₂·nH₂O (X = Cl, NO₃; n = 0−0.5) were established to inhibit in vitro the growth and reproduction of 100% of cancer cells of human mieloid leukaemia HL-60 at 10⁻⁴ M concentration. At 10⁻⁵ M concentration they inhibit only 10% of cells, and at 10⁻⁶ M concentration they do not possess anticancer activity.     

Serine and Threonine Schiff Base Esters React with β-Anomeric Peracetates in the Presence of BF3·Et2O to Produce β-Glycosides

Improved procedures are reported for the glycosylation of L-serine and L-threonine utilizing activated Schiff base glycosyl acceptors, which are less expensive and more efficient alternatives to published methods. L-serine or L-threonine benzyl ester hydrochloride salts were reacted with the diarylketimine bis-(4-methoxyphenyl)-methanimine in CH₃CN at rt to form the more nucleophilic Schiff bases 3a and 3b in excellent yield. These Schiff bases exhibited ring-chain tautomerism in CDCl₃ as shown by ¹H NMR. Schiff bases 3a and 3b, acting as glycosyl acceptors, reacted at rt with simple sugar peracetate donors with BF₃·OEt₂ promotion to provide the corresponding L-serine and L-threonine O-linked glycosides in excellent yields and purities. The dipeptide ester Schiff base Ar₂C = N-Ser-Val-OCH₃ 3e also reacted to provide β-glycosides in excellent yields, and without epimerization. With microwave irradiation the reactions were complete in 2 to 5 min. To investigate this reaction further, classical AgOTf-promoted Koenigs-Knorr reaction of D-glucopyranosyl, lactosyl, and maltosyl bromides were examined, providing the β-glycosides with yields ranging from 35% to 68%. The difference in reactivity between α- and β-carbohydrate peracetate donors was remarkable. The less configurationally stable D-xylopyranosyl tetra-acetate (a pentose) showed no selectivity (αvsβ-configuration) toward the Schiff bases.     

On the mechanism of the conversion of 6-chloropyrido[2,3-B]pyrazine into 1h-lmidazo[4,5-b] pyridine by potassium amide in liquid ammonia

The synthesis of a number of 2-R₁, 3-R₂-6-X-pyrido[2,3-b]pyrazines (1) is reported and their reaction with potassium amide in liquid ammonia investigated. Ring contraction into a 2-R-1H-imidazo[4,5-b]pyridine was found to occur with X = Cl, R₁ = H, R₂ = C₆H₅ (1b); X = Cl, R₁ = R₂ = C₆H₅ ( 1c ); X = Cl, R₁ = H, R₂ = t-C₄H₉ ( 1d ). Besides ring contraction, an increasing amount of dechlorination of 1 was found: 1a , 20%; 1b , 30%; 1d , 40%; 1c , 60%; 1g , 95%. 1e (X = Cl, R₁ = t-C₄H₉, R₂ = H) yields the unreactive anionic σ-adduct at C-3 i.e., 3-amino-2-t-butyl-6-chloro-3,4-dihydropyrido[2,3-b]pyrazine. The ring contraction only proceeds with X = Cl. 1b (X = F) gives an amino-defluorination, 1b (X = Br) exclusively undergoes reductive debromination. The ring contraction of 1a (X = Cl, R₁ = R₂ = H) is investigated by ¹⁵N- and ¹³C-labelling. It is concluded that the conversion into 1H-imidazo[4,5-b]pyridine proceeds via the reactive anionic σ-adduct at C-2, under exclusive elimination of C-2.     

Synthesis and reactivity of μ-η2-carbamato complexes of triosmium decacarbonyl

The synthesis of (-H)(-²-RRNCO₂)Os₃(CO)₁₀ (R=R=CH₃ 2a; R=R=CH₂CH₃,2b; R=CH₃, R=CH₂CH₃,2c) and their cyclic analogs (-H)(-²--CO₂)Os₃(CO)₁₀(n=42d,n=5,2e) from carbon dioxide, secondary amine, and Os₃(CO)₁₀(CH₃CN)₂ (1) are reported. A solid-state structure of2c reveals a bonding mode for the carbamato ligand very similar to that observed for related carboxylato complexes. Compound2c crystallizes in the orthorombic space group Pbca witha=9.136 (3),b=15.310 (4) andc=30.361 (5) Å;V=4247 ų,Z=8. Least-squares refinement of 2405 observed reflections gave a final agreement factor ofR=0.043 (R _w =0.043). The reactivity of the complexes2a–2e was examined. Compound2c or2b give good yields of the cluster derivatives (-H)(-X)Os₃(CO)₁₀ (X=Cl,3; X=OCH₃,4; X=N(CH₃)₂,7) when reacted with HX. Reaction of2a with P(CH₃)₃ at 68°C gives good yields of the otherwise difficult to obtain 1,1,2-(P(CH₃)₃)₃Os₃(CO)₉ (5). Evidence is presented that suggests that2a–2e form by oxidative addition of preformed carbamic acids to1.     

Substituted Diorganotin(IV) O,O’-Alkylene Dithiophosphates: Synthesis and Spectral Aspects

Six new substituted diphenyltin(IV) O,O′-alkylene dithiophosphates, (C₆H₅)₂Sn(X)S(S) POGO [G = —CH₂C(CH₃)₂CH₂—, X = Cl (1), SCN (3), ClO₄ (5); G = —CH₂C (C₄H₉)(C₂H₅)CH₂—, X = Cl (2), SCN (4), ClO₄ (6)], were synthesized by the reaction of the corresponding ammonium salts of the O,O’-alkylene dithiophosphates with an appropriate organotin(IV) chloride. The compounds were characterized on the basis of elemental and spectral analyses (ESI mass spectrometry, IR, ¹H, ¹³C, ³¹P, and ¹¹⁹Sn NMR). The presence of a four-coordinated Sn atom and monodentate O,O’-alkylene dithiophosphate moiety in compounds 1–4 as well as bidentate O,O’-alkylene dithiophosphate unit in compounds 5,6 is established.     

Efficient singlet oxygen generation by luminescent 2-(2′-thienyl)pyridyl cyclometalated platinum(II) complexes and their calixarene derivatives

Luminescent cyclometalated platinum(II) complexes, namely [Pt(Thpy)(PPh₃)X]ⁿ⁺ (HThpy = 2-(2′-thienyl)pyridine; X = Cl⁻ ( 1 ), n = 0; X = CH₃CN ( 2 ), pyridine ( 3 ), n = 1) and [Pt(Thpy)(HThpy)Y] ^{n +} (Y = Cl⁻ ( 4 ), n = 0; Y = pyridine ( 5 ), n = 1), exhibit structured emission with peak maximum at ∼556 and 598 nm in degassed acetonitrile and with emission quantum yield and lifetime of up to 0.38 and 26 μs, respectively. These complexes are efficient photosensitizers of singlet oxygen with yields up to >90%. Complex 5 exhibited photocytotoxicity towards cancer cells and fluorescence microscopic images of cells incubated with 5 reveal substantial uptake at the nucleus and mitochondria.     

Study on the Reaction of Electron‐deficient Cyclopropane Derivatives with Amines

Reaction of electron deficient cyclopropane derivatives cis‐1‐methoxycarbonyl‐2‐aryl‐6, 6‐dimethyl‐5, 7‐dioxa‐spiro‐[2,5]‐4,8‐octadiones (1a‐d) (X = CH₃, H, Cl, NO₂) with anilines (2a‐e) (Y = p‐CH₃, H, p‐Br, p‐NO₂, o‐CH₃) at room temperature gives N‐aryl‐trans, trans‐α‐carboxyl‐β‐methoxycarbonyl‐γ‐aryl‐γ‐butyrolactams (3a‐p) in high yields with high stereoselectivity. For example, 1a (X= CH₃) reacts with ammonia 4 or benzyl amine 5 at room temperature to give inner ammonium salt 6 or 7 in the yield of 83% or 97% respectively. The reaction mechanisms for formation of the products are proposed.     

Co(II) halide complexes with 2-amino-3-methylpyridinium and 2-amino-5-methylpyridinium: synthesis,crystal structures,and magnetic properties

Reaction of CoX₂ · nH₂O with either 2-amino-3-methylpyridine (3-MAP) or 2-amino-5-methylpyridine (5-MAP) in aqueous acid gave complexes, (3-MAPH)₂CoX₄ or (5-MAPH)₂CoX₄ (H₂O) _n [n = 0,1; X = Cl, Br; 3-MAPH = 2-amino-3-methylpyridinium, 5-MAPH = 2-amino-5-methylpyridinium]. The 3-MAPH salts are formed in the triclinic crystal system while the 5-MAPH salts are formed in the monoclinic crystal system. Three of these compounds exhibit weak antiferromagnetic interactions along with varying degrees of single-ion anisotropy, however, 1 shows easy-plane anisotropy and exhibits a mixture of ferromagnetic and antiferromagnetic interactions.     

A General Entry to 10-Halocolchicides and 9-Haloisocolchicides

Readily accessible 10-tosyloxycolchicide (1) and LiX (X=Cl or Br or I) in MeOH/BF₃Et₂O at reflux give 10-chloro- (2), 10-bromo- (4), or 10-iodocolchicide (5), in good yields. 9-Chloro- (7) and 9-bromoisocolchidide (8) can be similarly obtained from 9-tosyloxyisocolchidide (6) and the method applies also to troponoids.     

Reactions of methyl(pentafluorophenyl)- and methyl(pentafluorophenyl)phenylsilanes with electrophiles. A convenient preparative route to halogeno(methyl)pentafluorophenylsilanes C6F5SiMe2X and C6F5SiMeX2 (X=F, Cl and Br)

Halogeno(methyl)pentafluorophenylsilanes C₆F₅SiMe_nX_3−n (n=1, 2) (X=F, Cl, Br) were prepared in good yields from the corresponding phenylsilanes C₆F₅SiMe_nPh_3−n by reactions with the electrophiles aHF, HCl–AlCl₃, Br₂–AlBr₃ or AlX₃ (X=Cl, Br) halogenated hydrocarbons. Additionally, reactions of C₆F₅SiMe₃ and (C₆F₅)₂SiMe₂ with selected electrophiles were studied.     

Porous Solids of Divalent Metal Complexes Assembled Through Hydrogen Bonding and π–π Stacking Interactions

The compound N, N-di(6-methyl-2-pyridyl)formamidine (HDMepyF) has been exploited in preparation of porous materials of divalent metal complexes of the formulae M(HDMepyF)₂(NO₃)₂ (M=Cd, 1; Co, 2; Ni, 3) and M(HDMepyF)₂X₂ (M=Mn, X=Cl, 4; M=Mn, X=Br, 5; M=Ni, X=Cl, 6; M=Ni, X=Br, 7). Their structures have been determined by X-ray crystallography. Each metal center of these complexes is approximately octahedrally coordinated by four nitrogen and two halogen or oxygen donor atoms. Complexes 1– 5 and 7 self-assemble through similar hydrogen bonding motifs which involve the C–HsX (X=Cl, Br or O) hydrogen bondings and – stacking interactions between the HDMepyF ligand and the X atoms to form porous structures.