3- and 4-Pyridinecarboxylic acidN-oxide complexes with manganese(II), cobalt(II) and nickel(II) chlorides

Summary During interaction of ethanol-triethyl orthoformate solutions of nicotinic or isonicotinic acidN-oxides (LH and LH, respectively) with MCl₂ (M = Mn, Co, Ni), only one true adduct, of the Ni(LH)₃Cl₂ · 2 H₂O type was obtained. In all other cases, partial substitution of Cl^– ions with the corresponding pyridinecarboxylateN-oxide anionic ligands (L or L) occurred. As a result, mixed ligands (LH-L or LH-L) were precipitated, as follows: Mn(LH)₂LCl, Co(LH)LCl, Mn(LH)LCl · 4H₂O, Co(LH)LCl · H₂O and Ni₂(LH)LCl₃ · 6 H₂O. The insolubility of the new complexes in all common solvents, combined with the pronounced tendency of the 3- and 4-pyridinecarboxylates and theirN-oxides to function as bidentate bridging ligands, favours bi- or polynuclear structures. Spectral data suggest that Ni(LH)₃Cl₂ · 2 H₂O is hexacoordinate, and the rest of the new complexes pentacoordinate. Bi- or polynuclear structures, involving double -M-(L)₂-M- or-M-(LH)₂-M- and single -M-(L)-M- or-M(L)-M-(LH)-M- bridges, were proposed on the basis of the overall evidence; additional features of the proposed structural types are: exclusively coordinated chloro ligands, in all cases; aqua ligands [Co(LH)LCl · H₂O]; lattice water [Ni(LH)₂Cl₂ · 2H₂O]; both lattice and coordinated H₂O [Mn(LH)LCl · 4H₂O, and Ni₂(LH)LCl₃ · 6H₂O]; and, with the exception of Ni₂(LH)LCl₃ · 6 H₂O, terminal, unidentate, N-O oxygen-bonded LH or LH ligands.Abstracted in part from the Ph.D. Thesis (in preparation) of L. S. Gelfand, Drexel University.     

Fluorescent chemosensors containing a Ru(tpy)2 2+ core and open-chain polyazaalkanes

4-[4-(Bromomethyl)phenyl]-2,2:6,2-terpyridine reacts with triethylenetetraamine or tetraethylenepentaamine in CH₂Cl₂ to yield the ligands L¹ and L², respectively. Reaction of L¹ and L² with Ru(mtpy)Cl₃ (mtpy = 4-methyl-2,2:6,2-terpyridine) in MeOH yielded, after column chromatography and precipitation with [NH₄][PF₆], the compounds [Ru(L¹)(mtpy)][PF₆]₂ and [Ru(L²)(mtpy)][PF₆]₂. These metallo-receptors contain triethylenetetraamine or tetraethylenepentaamine recognition sites and [Ru(tpy)₂]²⁺ cores as fluorescent signalling subunits. The fluorescent behaviour of [Ru(L¹)(mtpy)]²⁺ and [Ru(L²)(mtpy)]²⁺ in the presence of metal ions and anions has been studied in MeCN:H₂O (70:30 v/v) as a function of the pH.     

Copper(II) chloride complexes of 2-(4′-Methyl-2′-pyridyl)-benzoxazole,their sulphur and nitrogen analogues and 2-(4′-Methyl-2′ {or8′} -quinolyl)benzoxazoles

Summary Copper(II) complexes CuLCl₂, where L=2-(4-methyl-2-pyridyl)benzimidazole(mpbi); 2-(4-methyl-2-pyridyl)benzothiazole(mpbt); 2-(4-methyl-2-pyridyl)benzoxazole (mpbo); 2-(4-methyl-2-quinolyl)benzoxazole (mqbo); 2-(4-methyl8-quinolyl)benzoxazole (mqbo), and Cu(mpbi)₂Cl₂(H₂O) have been synthesized and characterized by conductivity and magnetic measurements as well as by i.r., electronic and e.s.r. spectra. The ligands are bidentate donors through the pyridine and isoxazole nitrogen atoms. The CuLCl₂ complexes exhibit spectral properties consistent with CuN₂Cl₂ chromophores differing in the degree of tetrahedral distortion, which is found to parallel the steric hindrance near the donor sites. Cu(mpbi)₂ Cl₂(H₂O) is five-coordinate.     

Mono and dinuclear cationic rhodium(I) and iridium(I) complexes with sulphur donor and group Vb ligands

Summary Rhodium(I) and iridium(I) mixed complexes of the formulae [M(diolefin)LL]ClO₄, [M(diolefin)L₂L]ClO₄, [(diolefin)LIr(-L)₂IrL(diolefin)](ClO₄)₂, [(diolefin)LM(-L-L)ML'(diolefin)](ClO₄)₂, [(diolefin)Rh{-(L-L)}₂Rh(PPh₃)₂](ClO₄)₂ and [(diolefin)LIr{-(L-L)}₂IrL (diolefin)](C1O₄)₂, (L=monodentate sulphur ligand, L-L=bidentate sulphur ligand, L=group Vb ligand; M=Rh, diolefin=1,5-cyclooctadiene (COD) or 2,5-norbornadiene (NBD); M=Ir, diolefin=COD) are described.Author to whom all correspondence should be directed.     

Synthesis and characterisation of some complexes of manganese(II) and iron(II) picrates with heterocyclic amines

Summary Complexes of manganese(II) and iron(II) picrates with various bidentate (L) and monodentate (L) heterocyclic bases have been synthesised; their compositions have been established as [ML₃]A₂ (1), [ML₂ · 2 H₂O]A₂ (2), [ML₆]A₂ (3) and [ML4 · 2 H₂O]A₂ (4), where M = Fe^II and Mn^II, L = 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen) in (1), A = picrate anion; M = Mn^II, L = bipy and phen in (2); M = Fe^II, L = pyridine (py), 4-picoline (4-pic) and 3-picoline (3-pic) in (3); M = Mn^II, L = py, 4-pic, quinoline (quin) and 2,6-lutidine (2,6-lut) in (4) and also M = Fe^II, L = quin and 2,6-lut.     

New chiral acyclic analogs of 2′-deoxynucleosides

Convenient methods for the synthesis of chiral 2,3-seco-2-deoxynucleosides were developed. An isopropylidene protective group was used to block the 3,5-hydroxy groups in 2,3-seco-uridine. Conversion of the hydroxymethyl group to a methyl group was accomplished by chlorination with a mixture of CCl₄ and Ph₃P with subsequent reduction with n-Bu₃SnH. 2,3-seco-2-Deoxyuridine was obtained after deacetonation. The (S) enantiomer was similarly synthesized starting from 1-(-D-arabinofuranosyl)uracil. 3-O-tert-Butyldimethylsilyl-5-O-(p-monomethoxytrityl)-2,3-seco-2-deoxyuridine, which has optically active centers at C₍₁₎ and C₍₄₎, was also synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 822–826, June, 1988.The authors thank Professor M. Ya. Karpeiskii for his constant interest in this research.     

Cobalt(II) and nickel(II) chloride complexes with some 2-(4′-Methyl-2′-pyridyl and 2′- or 8′-quinolyl)benz-X-azoles

Summary Complexes of general formula ML_mCl₂ · nH₂O, where M=cobalt(II) or nickel(II); L=2-(4-methyl, 2-pyridyl)-benzimidazole (mpbi), 2-(4-methyl, 2-pyridyl)benzothiazole (mpbt), 2-(4-methyl, 2-pyridyl)benzoxazole (mpbo), 2-(4-methyl, 2-quinolyl)benzoxazole (mqbo), or 2-(4-methyl, 8-quinolyl)benzoxazole (mqbo); m=1,2; n=0–3, were prepared and characterized by t.g.a., conductance and magnetic measurements, i.r. and diffuse-reflectance electronic spectra.All the ligands behave as bidentate and coordinate through the pyridine- and isoxazole-nitrogen atoms.The nickel complexes have distorted octahedral or fivecoordinate structures. The cobalt complexes arepseudo-tet- rahedral except Co(mpbo)₂Cl₂·2H₂O where the metal is six-coordinate.     

Synthesis and characterization of some methyl complexes of palladium(II). Part 2(1)

Summary Dichloro complexes of Pd^II, [Pd(L–L)Cl₂], where L–L=1-(thiomethyl)-2-(diphenylarsino)ethane (S–As) or 1-(thiomethyl)-2-(diphenylphosphino)ethane (S–P) andtrans-[PdL₂Cl₂], where L=diphenyl(2-phenylethyl)-phosphine (PE), diphenyl(1-naphthyl)phosphine (PN) orN-methyl-2-thiophenealdimine (SN), have been prepared and characterized. The reactions of these complexes with MeLi were investigated. The dimethyl complexes [Pd(L–L)Me₂] (L–L=S–As, S–P) and [Pd(PE)Me₂] were isolated and characterized. Reaction of [Pd(L–L)Me₂] (L–L=S–As, S–P) with HCl affords the monomethyl derivatives [Pd(L–L)Me(Cl)]. In contrast to the Pt analogues, [Pd(L–L)Me₂] and [Pd(L–L)Me(Cl)] are relatively less stable than [Pt(L–L)Me₂] and [Pt(L–L)Me(Cl)].     

Cobalt(II) and nickel(II) chloride and bromide complexes of 2-(2′-methyl-8′-quinolyl)benzoxazole and 2-(2′ or 4′-methyl 8′-quinolyl)benzimidazole

Summary Cobalt(II) and nickel(II) halide complexes of the ligands 2-(2-methyl-8-quinolyl)benzoxazole (mqbo), 2-(2-methyl8quinolyl)benzimidazole (mqbi) and 2-(4-methyl-8-quinolyl)benzimidazole (mqbi) were synthesized and characterized by analytical, thermogravimetric, conductivity and magnetic data, and i.r. and electronic spectra.The ligands are bidentate N-donors yielding complexes where the coordination geometry depends on the metal ion and steric hindrance. All the cobalt complexes have formula [CoL₂X₂] and distorted tetrahedral geometry. Different types of nickel compounds were obtained: i) complexes of formula NiLX₂ · n H₂O (or EtOH) (L = mqbo or mqbi; n=0–1.5) which arepseudo-tetrahedral or five-coordinate and ii) complexes NiL₂X₂ · n H₂O (L = mqbi, n=3 or 4) where the metal is bound to four nitrogen atoms and the overall coordination geometry is tetragonal. The structural changes occurring after removal of water or alcohol from the complexes are also reported.     

Mixed-ligand and binuclear complexes of oxovanadium(IV)

Summary Mixed ligand complexes of the type [VOLA]ClO₄ where L=5-bromosalicylaldehyde (L) or 5-nitrosalicylaldehyde (L) and A=2, 2-dipyridyl (A) or 1, 10-phenanthroline (A) have been prepared. Treatment of the mononuclear complexes, [VOLA]ClO₄, withp-phenylenediamine (ppd) orm-phenylenediamine (mpd) yielded homobinuclear [VOLA-NC₆H₄N-LAVO](ClO₄)₂, complexes, which were characterised by elemental analyses, spectra, magnetic susceptibility and molar conductance measurements.     

Titanium(IV) and zirconium(IV) derivatives of tetradentate schiff bases

Summary Titanium and zirconium isopropoxides react with the tetradentate Schiff bases, I)is-salicylaldehyde-o-phenylenediimine (SBH₂ ) and bis-salicylaldehyde-p-phenylencdiimine (SBH₂) in anhydrous benzene in 1: 1 and 1 :2 molar ratios to give almost quantitative yields of M(OPr-i)₂ (SB) and M(OPr-i)2(SB)(SBH), where M = Ti or Zr and [SB]² is the anion of the corresponding Schiff base, SBH₂. The i.r. spectra of the completes have been recorded and tentative assignments for C=N and C-O stretching frequencies made.     

Kinetics and mechanism of nucleophilic substitution of dichloro{1-methyl-2-(arylazo)imidazole}palladium(II) by pyridine bases

The reaction of dichloro{1-methyl-2-(arylazo)imidazole}palladium(II), Pd(RaaiMe)Cl₂ where RaaiMe = p-R–C₆H₄N=N–C₃H₂N₂-1-Me; R = H(1), Me(2), Cl(3), with pyridine bases [RPY: R = H (a), 4-Me (b), 4-Cl (c), 2-Me (d), 2,6-Me₂ (e), 2,4,6-Me₃ (f)] has been studied spectrophotometrically in MeCN at 451 nm. The products (4) have been isolated and characterised as trans-Pd(RPy)₂Cl₂. The kinetics of the nucleophilic substitution has been examined under pseudo-first-order conditions at 298 K. A single phase reaction step has been observed for bases such as Hpy (a), 4-MePy (b) and 4-ClPy (c) and follows the rate law: rate = (a + k[RPy]²[Pd(RaaiMe)Cl₂]). The bases 2-MePy (d), 2,6-Me₂Py (e) and 2,4,6-Me₃Py (f) exhibits a bi-phasic reaction and follows the rate laws: rate–1 = (a + k[RPy][Pd(RaaiMe)Cl₂]) and rate–2 = (a + k[RPy][Pd(RaaiMe)-Cl₂]), where k is the third-order rate constant; k is the second-order first phase rate constant, k is the second-order second phase rate constant and a/a/a correspond to the solvent dependent constant of the respective reaction path. The rate data supports a nucleophilic association path. External addition of Cl^– (LiCl) suppresses the rate, which follows the order: k/k/k (3) > k/k,k (1) > k/k,k (2). The k values are linearly related to the Hammett constants. The 2-substituted pyridines (d–f) remarkably reduce the rate and show a bi-phasic reaction behaviour as compared with 4-Rpy (a–c). This is attributed to the steric effect that destabilises the transition state. The rate decreases with increasing steric crowding at the ortho-position and follows the order: (d) > (f) > (e). The 4-substituted pyridines control the rate via an inductive effect and follow the order: (b) > (a) > (c).     

Polynuclear rhodium(I) complexes with 3,3′,5,5′-tetramethyl-4,4′-bipyrazole and 4,4′-methylen-bis(3,5-dimethylpyrazole)

Summary The reaction of [RhClY₂]₂ (Y₂ = diolefin; Y = CO) with 3,3,5,5-tetramethyl-4,4-bipyrazole and 4,4-methylen-bis (3,5-dimethylpyrazole) (H₂LL) leads to binuclear complexes of the type (H₂LL) [RhClY₂]₂. The addition of triethylamine to the latter complexes gives polynuclear [(LL){RhY₂}₂]_n derivatives. Related compounds of formula [(LL){RhX(PPh₃)}₂]_n (X = CO or CS) are also reported.Part of this paper was presented at the VIIIth International Congress of Heterocyclic Chemistry which was held in Graz, Austria. August 1981.     

Structure and Magnetic Properties of Solid Solutions of Molecular Magnetics Based on Ni(II) and Co(II) Complexes with Nitroxyl Radicals

Ni(II) and Co(II) complexes with deprotonated paramagnetic enaminoketones 4(3,3,3trifluorine2oxopropylidene) 2,2,5,5tetramethyl3imidazolidine1oxyl (L) and 4(3,3,3trifluorine1chlorine2oxopropylidene)2,2,5,5tetramethyl3imidazolidine1oxyl (L¹) and alcohols are shown to form continuous solid solutions Ni_xCo_1-xL₂(C₂H₅OH)₂ and Ni_xCo_1-xL₂ ¹(CH₃OH)₂. Single crystal Xray diffraction analysis showed that concentration variation practically does not affect the structural characteristics of the solid solutions. Distinguishing features if the magnetic behavior of Ni_xCo_1-xL₂ · (C₂H₅OH)₂ and Ni_xCo_1-xL₂ ¹(CH₃OH)₂ are the antiferromagnetic interaction of the moments of the nickel and cobalt sublattices inside the polymeric layers and the antiferromagnetic nature of interlayer interaction of the magnetic moments.     

Über Tetrahydrospiro [cyclohexan-1,4′(1′H)-chinazolin]-2′(3′H)-one

Zusammenfassung Cyclohexanon bzw. Cyclopentanon sowie ihre durch Aldolreaktion entstehenden Dimeren reagieren mit Harnstoff im sauren Medium zu 5,6,7,8-Tetrahydrospiro[cyclohexan-1,4(1H)-chinazolin]-3(2H)-onen (2) bzw. zum Dihydrospiro-(cyclopentan-1,4(1H)-5H-cyclopenta[d]pyrimidin)-2(3H)-on (10). Substituierte Harnsotoffe geben Gemische der isomeren 5,6,7,8-Tetrahydro- und 4a,5,6,7-Tetrahydroverbindungen (2, 3) bzw. 6,7-Dihydro-tH- und 5,6-Dihydro-4aH-verbindungen (10, 11). Charakteristisch für2 (3),10 (11) ist die Reaktivität der Kernstellen 8 bzw. 7 gegenüber elektrophilen Agentien (2f-v, 3f-j, 9 a-i, 10 d-f). Äthylmalonsäurebis-trichlorphenylester bzw. Formaldehyd und prim. Amine führen2 in ein partiell hydriertes 1H-Pyrido[3,2,1-ij]chinazolintrion (6) bzw. 1H-Pyrimido[5,6,1-ij]chinazolinon (7) über. Die 1-Alkylverbindungen (2) geben mit Formaldehyd und primären Aminen Hexahydro-8a-hydroxy-4a,8-propanospiro-(cyclohexan-1,4(1H)-pyrido[4,3-d]pyrimidin)-2(3H)-one (8).

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Heterocycles, XXV: tetrahydrospiro [cyclohexane-1,4(1H)-quinazoline]-2(3H)-ones

Cyclohexanone and cyclopentanone, resp., as well as their dimers (formed by aldol reaction) react with urea in the presence of acids to 5,6,7,8-tetrahydrospiro[cyclohexane-1,4-(1H)-quinazoline]-3(2H)-ones (2) and to the dihydrospiro-(cyclopentane-1,4(2H)-5H-cyclopenta[d]pyrimidine)-2(3H)-one (10), resp. Substituted ureas give the isomeric 5,6,7,8-tetrahydro- and 4a,5,6,7-tetrahydro compounds (2, 3), and 6,7-dihydro-5H- and 5,6-dihydro-4aH-compounds (10, 11), resp. Characteristic for2 (3),10 (11) is the reactivity of the nuclear places 8 and 7 with electrophilic agents (2f-v, 3f-j, 9a-i, 10d-f). Ethylmalonic acid bistrichlorophenylester resp. formaldehyde and primary amines react with2 to the partially-hydrogenated 1H-pyrido[3,2,1-ij]-quinazolinetrione (6) and 1H-pyrimido[5,6,1-ij]-quinazolinone (7), resp. The 1-alkyl compounds (2) give with formaldehyde and primary amines hexahydro-8a-hydroxy-4a, 8-propanospiro(cyclohexane-1,4-(1H)-pyrido[4,3-d]pyrimidine)-2(3H)-ones (8).

     

Molecular orbital calculations of iron(II) complexes of diimine ligands

Summary Molecular orbital calculations using-, the INDO method have been carried out fm the [FeL(CN)₄]² and [FeLH(CN)₄] complexes, as well as for the tree ligands, with L 2 × pyridine, 1,10-phenanthroline.2,2-bipyridyl. 2,2-rimidine, 2, 3,3-bipyridazine and 4.4-bipyrimidine. Calculations of residual charge at carbon atoms in the ligand rings. correlating with relative nucleophilicity of the compounds, corresponds with observed differences of rate of reaction of the complex [FeI;]² With nucleophiles.     

Synthesis,physico-chemical and biological studies on oxovanadium(IV) derivatives of mercaptotriazoles

Summary Complexes of 3-methyl- or 3-ethyl-4-amino-5-thiolato-1,2,4-triazole (LH) and its Schiff base derivatives with oxovanadium(IV), of the types [VOL₂(H₂O)], [VOL₂-(H₂O)] and [VOL(H₂O)₂] (where LH = Schiff bases derived from condensation of LH with benzaldehyde, 2-chlorobenzaldehyde, 4-methoxybenzaldehyde or acetophenone; LH₂ = Schiff bases derived from condensation of LH with salicylaldehyde or o-hydroxyacetophenone) have been prepared and characterized by elemental analyses, electrical conductance, magnetic moments and spectral data. The thermal behaviour of selected complexes was investigated by t.g., d.t.g. and d.s.c. techniques. The antifungal and antiviral activities of the Schiff bases and their corresponding complexes were also investigated.Author to whom all correspondence should be directed.     

Zirkon(IV) derivate von bifunktionellen drei- und vierzähnigenSchiffschen Basen

Reactions of zirconium isopropoxide-isopropanolate with bifunctional tridentateSchiff bases such as acetylacetone-(2-hydroxy-anil), benzoylacetone-(2-hydroxy-anil) and salicylidene-o-aminophenol and bifunctional tetradentateSchiff bases such as bisacetylacetone ethylenediimine, bisbenzoylacetone ethylenediimine and bissalicylidene ethylenediamine have been investigated in different molar ratios. The resulting products of the type Zr(OPr ⁱ)₂(SB), Zr(SB)₂, Zr(OPr ⁱ)₂(SB) and Zr(SB)₂ (whereSB andSB represent the anions of the bifunctional tridentate and bifunctional tetradentateSchiff bases respectively) have been isolated in almost quantitative yields. I.R. spectral studies of a few representative derivatives have been made and their molecular weights determined ebullioscopically in benzene. Thermogravimetric analysis of the salicylidene-o-aminophenol derivative has also been carried out.

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Mit 1 Abbildung     

Transition metal complexes of γ-mercaptoalkylpiperidines

Summary Complexes with 1-methyl-3-(mercaptomethyl)piperidine (LH) and 1-methyl-2-(2-mercaptoethyl)piperidine (LH) Ligands in their thiolato (R), andN-protonated (HR) orN-methylated (MeR) zwitterionic form, of stoichiometry MR₂ (M=Ni, R=L or L; M=Cd, R=L), MR (M=Cu or Ag, R=L and L), [Ni(MeR)₂]I₂ · nH₂O (R=L, n=1; R=L, n=2), [Ni(HR)₂]X₂ (R=L or L, X=ClO₄; R=L, X=Br), and [Ag(HR)] ClO₄ (R=L) have been prepared and characterized. According to i.r. and electronic spectra, and magnetic measurements the nickel complexes exhibit polymeric frameworks built up from mercapto-bridged metal atoms in square-planar environments. Complexes with copper, silver, and cadmium exhibit similar polymeric arrangements through bridging sulphur atoms but with a different geometry at the metal centers, the first two being mainly linear, as anticipated, and the latter tetrahedral. In no case does coordinationvia nitrogen take place and therefore these ligands behave simply as mercaptides.     

Reactivity and solvatochromism of 2,2′-bi(4H-5,6-dihydrothiazine)-tetracarbonylmolybdenum(O)

Summary The dependence of the charge-transfer frequency for [Mo(CO)₄(btz)], btz = 2,2-bi(4H-5,6-dihydrothiazine), on solvent is described, and the solvatochromic behaviour of this compound compared with that of other [Mo(CO)₄(LL)] species, with LL = 2,2-bipyrimidine or 2,2-bipyridine, and of iron(II) analogues [Fe(btz)₂(CN)₂] and [Fe(bipy)₂(CN)₂]. Kinetics of solvolysis (k, H, S) are reported for [Mo(CO)₄(btz)] in methanol, acetonitrile, and dimethyl sulphoxide. These kinetic results are analysed into initial state and transition state contributions. A parallel analysis of the solvatochromic results for [Mo(CO)₄(btz)] into ground state and excited state solvation contributions is compared with similar analyses for the solvatochromic organic compoundsp-nitroanisole and dimethylindoaniline.