Unusual removal of the ethylene ketal protection from 2,3-dichloro-4,4-ethylenedioxycyclopent-2-en-1-one under alkaline conditions. Simple synthesis of naturally occurring cyclopentenedione analogs

A reaction of 2,3-dichloro-4,4-ethylenedioxycyclopent-2-en-1-one with MeONa in MeOH to furnish 2-chloro-3-hydroxycyclopent-2-en-1,4-dione has been studied. The latter under the action of CH₂N₂ has been converted to the corresponding enol ether. This methodology has been used for the synthesis of 4-chloro-5-methoxy-2-cinnamylidenecyclopent-4-en-1,3-diones and related compounds starting from the parent dichlorocyclopentenone.     

Synthesis of naphtho[2',3':4,5]imidazo[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3]-thiazole-5,10-dione and naphtho[2',3':4,5]imidazo-[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3]benzothiazole-7,12-dione

The reaction of 2,3-dibromo-1,4-naphthoquinone with 2-aminothiazole in MeONa/MeOH at 60oC for 3 h gave naphtho[2',3':4,5]imidazo[2,1-b][1,3]thiazole-5,10-dione in 64% yield. The reaction of 2,3-dibromo-1,4-naphthoquinone with 2-aminobenzothiazole under the above-mentioned conditions gave 2-(benzo[d]thiazol-2-ylamino)-3-bromonaphthalene-1,4-dione in 64% yield, which on treatment with Na/THF or NaN₃/acetone under reflux conditions gave naphtho[2',3':4,5]imidazo[2,1-b][1,3]- benzothiazole-7,12-dione in 69 and 56% yields, respectively.     

1,3-Dipolar cycloaddition ofin situ generated 2,2-dimethyl-and 2,2-dichlorodiazocyclopropanes to 3,3-dimethylcyclopropene

2,2-Dimethyl- and 2,2-dichlorocyclopropyl-N-nitrosoureas were synthesized for the first time. Under the action of MeONa/MeOH at ?10°C, these compounds generate the corresponding 2,2-dimethyl- and 2,2-dichlorodiazocyclopropanes, which are readily trapped by 3,3-dimethylcyclopropene to give the products of 1,3-dipolar cycloaddition,viz., isomeric substituted spiro(2,3-diazabicyclo[3. 1 .0] hex-2-ene-4,1 ′-cyclopropanes), in yields of about 70%,     

Photochemical Synthesis and Some Reactions of 7-Oxa-and 7-Thiatricyclo[3.2.1.03,6]octan-2-ones

Irradiation (λ = 350 nm) of newly synthesized 2-acetyl- or 2-methyl-2-(alk-2-enyl)furan-3(2H)-ones 1 and 2-acetyl- or 2-methyl-2-(prop-2-enyl)thiophen-3(2H)-ones 2 affords the corresponding 1-acetyl- or 1-methyl-substituted 7-oxa- and 7-thiatricyclo[3.2.1.0^3,6]octan-2-ones 10 and 11 , respectively, via regioselective intramolecular [2 + 2] photocycloaddition in 65–95% yield (Scheme 2). The 1-acetyl-substituted O-derivatives 10b and 10c undergo ring opening on treatment with MeONa in MeOH at–78° to afford stereoselectively methyl 3-exo-acetyl-2-oxabicyclo[3.2.0]heptane-7-endo-carboxylates 12b and 12c , respectively, while a 2:1 diastereoisomeric mixture of methyl 3-acetyl-2-thiabicyclo[3.2.0]heptane-7-endo-carboxylates 13 and 14 is obtained from the corresponding S-derivative 11b . The outcome of the Huang-Minlon reduction of the 1-methyl-substituted ketones 10a and 11a is again influenced by the heteroatom in the tricycle. While 1-methyl-7-oxatricyclo[3.2.1.0^3,6]-octane ( 15 ) is the only product from the corresponding oxatricyclooctanone 10a , a 1:2 mixture of 1-methyl-7-thiatricyclo[3.2.1.0^3,6]-octane ( 16 ) and 3-methylbicyclo[3.1.1]hept-2-ene-6-endo-thiol ( 17 ) is obtained from the analogous S-compound 11a , both products stemming from a common carbanion precursor.     

Linear {NiII–LnIII–NiII} Complexes Containing Twisted Planar Ni(μ‐phenolate)2Ln Fragments: Synthesis,Structure, and Magnetothermal Properties

Sequential reaction of a multisite LH₄ ligand {2‐[2‐hydroxy‐3‐(hydroxymethyl)‐5‐methylbenzylideneamino]‐2‐methylpropane‐1,3‐diol} with appropriate lanthanide salts followed by the addition of Ni(NO₃)₂ ? 6 H₂O in a 4:1:2 stoichiometric ratio in the presence of triethylamine afforded four heterobimetallic trinuclear complexes [Ni₂Gd(LH₃)₄] ? 3 NO₃ ? 3 MeOH ? H₂O ? CH₃CN ( 1 ), [Ni₂Tb(LH₃)₄] ? 3 NO₃ ? 3 MeOH ? CH₃CN ( 2 ), [Ni₂Dy(LH₃)₄] ? 3 NO₃ ? 3 MeOH ? H₂O ? CH₃CN ( 3 ), and [Ni₂Ho(LH₃)₄] ? 3 NO₃ ? 3 MeOH ? H₂O ? CH₃CN ( 4 ). Complexes 1 – 4 possess linear trimetallic cores with a central lanthanide ion. Magnetic studies revealed a predominant ferromagnetic interaction between the Ni and Ln centers. Alternating current susceptibility measurements of complex 3 showed a small frequency dependence of the out‐of‐phase signal, χ′′_M , under zero direct current field, but without achieving a net maximum above 2 K. Magnetic studies on 1 revealed that it has a significant magnetocaloric effect.     

Synthesis and Helical Structures of Poly(ω‐alkynamide)s Having Chiral Side Chains: Effect of Solvent on Their Screw‐Sense Inversion

New ω‐alkynamides, (S)‐HC?CCH₂CONHCH₂CH(CH₃)CH₂CH₃ ( 1 ) and (S)‐HC?CCH₂CH₂CONHCH(CH₃)CH₂CH₂CH₂CH₂CH₃ ( 2 ) were synthesized and polymerized with a rhodium catalyst in CHCl₃ to obtain cis‐stereoregular poly(ω‐alkynamide)s (poly( 1 ) and poly( 2 )). Polarimetric, CD, and IR spectroscopic studies revealed that in solution the polymers adopted predominantly one‐handed helical structures stabilized by intramolecular hydrogen bonds between the pendent amide groups. This behavior was similar to that of the corresponding poly(N‐alkynylamide) counterparts (poly( 3 ) and poly( 4 )) reported previously, whereas the helical senses were opposite to each other. The helical structures of the poly(ω‐alkynamide)s were stable upon heating similar to those of the poly(N‐alkynylamide)s, but the solvent response was completely different. An increase in MeOH content in CHCl₃/MeOH resulted in inversion of the predominant screw‐sense for poly( 1 ) and poly( 2 ). Conversely, poly( 3 ) was transformed into a random coil, and poly( 4 ) maintained the predominant screw‐sense irrespective of MeOH content. The solvent dependence of predominant screw‐sense for poly( 1 ) and poly( 2 ) was reasonably explained by molecular orbital studies using the conductor‐like screening model (COSMO).     

Unexpected Products from the Reaction of 2,2,4,4- Tetramethylcyclobutane-1,3-dione with the Ma˛kosza Reagent

Reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione ( 2 ) under phase-transfer-catalysis (PTC) conditions (CHCl₃/aqueous NaOH) yielded a complex mixture of unexpected products (Scheme 2). From the organic phase, three ring-enlarged products 7 – 9 with a cyclopentane-1,3-dione (cf. 7 and 9 ) or a cyclopentenone skeleton (cf. 8 ) were isolated in low yield. After acidification of the aqueous phase, the oily residue was treated with CH₂N₂, and methyl 3-oxopentanoate 12 and dimethyl 2-hydroxybutanedioate 13 were obtained in almost equal amounts. The structures of 8 and 9 were established by X-ray crystal-structure analysis (Fig.). Mechanisms for the formation of the products, initiated by nucleophilic attack of trichloromethanide ion and opening of the cyclobutane ring, are proposed in Schemes 3 and 4.     

Enantiomer separation of rac-2,2′-dihydroxy-1,1′-binaphthyl (BNO) by inclusion complexation with racemic or achiral ammonium salts and a novel transformation of a 1:1:1 racemic complex of BNO, Me4N·Cl and MeOH into a conglomerate complex in the solid state

The complete simultaneous and mutual enantiomer resolution of 2,2′-dihydroxy-1,1′-binaphthyl (BNO) and N-(3-chloro-2-hydroxypropyl)-N,N,N-trimethylammonium chloride, Me₃N⁺CH₂CH(OH)CH₂Cl·Cl⁻ into their enantiomers by inclusion complexation between their racemates in EtOH in the presence of a chiral seed crystal is reported. The enantiomer resolution of the rac-BNO was also accomplished easily by inclusion complexation with achiral ammonium salts, N-(2-hydroxyethyl)-N,N,N-trimethylammonium chloride, Me₃N⁺CH₂CH₂OH·Cl⁻ and tetramethylammonium chloride, Me₄N⁺·Cl⁻. Inclusion complexation of the rac-BNO with Me₃N⁺ CH₂CH₂OH·Cl⁻ gave only a 1:1 conglomerate inclusion complex but not a racemic complex. Recrystallization of the rac-BNO and an equimolar amount of Me₄N⁺·Cl⁻ from MeOH (7 ml) and MeOH (15 ml) gave a 1:1:1 racemic complex, BNO·Me₄N⁺·Cl⁻·MeOH and a 1:1 conglomerate complex, BNO·Me₄N⁺·Cl⁻, respectively. Novel transformation of the former racemate into the latter conglomerate occurred by heating or by exposure to MeOH vapor in the solid state.     

Synthesis of N-acetyl-3,3a,4,8b- and -1,3a,4,8b-tetrahydrocyclopenta[b]indoles from N- and 2-(cyclopent-2-en-1-yl)anilines

Reactions of 2-bromo-N-(cyclopent-2-en-1-yl)-4-methylaniline and N-(cyclopent-2-en-1-yl)-2-iodo-4,6-dimethylaniline with acetyl bromide in the presence of potassium carbonate gave mixtures of syn and anti atropisomers of the corresponding N-acetyl derivatives at ratios of 1: 1 and 3: 2 respectively. Heating of these mixtures in toluene in the presence of Pd(OAc)₂, PPh₃, Et₃N, and K₂CO₃ (KOAc) afforded mixtures of isomeric N-acetyl-7-methyl-3,3a,4,8b- and -1,3a,4,8b-tetrahydrocyclopenta[b]indoles at a ratio of 3: 1 or N-acetyl-5,7-dimethyl-3,3a,4,8b- and -1,3a,4,8b-tetrahydrocyclopenta[b]indoles at a ratio of 2: 3. N-Acetyl-3,3a,4,8b-tetrahydrocyclopenta[b]indole was found to undergo thermal isomerization into N-acetyl-1,3a,4,8btetrahydrocyclopenta[b]indole.     

Massive Steric Hindrance in Two ‘Thiocarbonyl Ylides': Cycloadditions with Tetra‐Acceptor‐Substituted Ethylenes via Zwitterionic Intermediates

The switch from a concerted to a two‐step pathway of 1,3‐dipolar cycloadditions was recently established for the reactions of sterically hindered ‘thiocarbonyl ylides' with acceptor ethylenes. This mechanism via zwitterionic intermediates is studied here for 1,3‐dipoles 5A and 5B , which are derived from 2,2,5,5‐tetramethylcyclopentanethione and 1,1,3,3‐tetramethylindan‐2‐thione, respectively, and contain a highly screened reaction center. In the reactions of 8A and 8B (the precursors of 5A and 5B ) with dimethyl 2,3‐dicyanofumarate ( 15 ) and 2,3‐dicyanomaleate ( 16 ), virtually identical ratios of cis‐ and trans‐thiolanes were observed ( 17 / 18 93 : 7 for 5a and 94 : 6 for 5B ). Thus, full equilibration of rotameric zwitterions precedes cyclization; an anteceding disturbing isomerization 15 ⇌ 16 had to be circumvented. The cis,trans assignment of the cycloadducts rests on three X‐ray analyses. The kinetically favored cis‐thiolanes 17 isomerize at >80° to 18 (trans), and irreversible cleavage leads to thione 7 and trans,cis isomeric dimethyl 1,2‐dicyanocyclopropane‐1,2‐dicarboxylates ( 27 and 28 , resp.). Furthermore, the zwitterionic intermediates equilibrate with the cyclic seven‐membered ketene imine 21 , which was intercepted under conditions where the solvent contained 2 vol‐% of H₂O or MeOH. Lactams 22 were obtained with H₂O in high yields, and the primary products of capturing by MeOH were the cyclic ketene O,N‐acetals 23 , which subsequently tautomerized to the lactim methyl ethers 24 . When 5B was reacted with ethenetetracarbonitrile in CDCl₃/MeOH (98 : 2 vol‐%), the analogous cyclic ketene imine 13B was trapped to the extent of 93%.     

Preparation of poly(alkylenebenzimidazole) by ruthenium complex catalyzed polycondensation of 3,3′‐diaminobenzidine with α,ω‐diols

The reactions of 3,3′‐diaminobenzidine with 1,12‐dodecanediol in 1 : 1–1:3 molar ratios in the presence of RuCl₂(PPh₃)₃ catalyst give poly(alkylenebenzimidazole), [ (CH₂)₁₁ O (CH₂)₁₁ Im / (CH₂)₁₀ Im ]_n (Im: 5,5′‐dibenzimidazole‐2,2′‐diyl) (I_a‐I_d) in 71–92% yields. The relative ratio between the [(CH₂)₁₁ O (CH₂)₁₁ Im ] unit (A) and the [‐ (CH₂)₁₀ Im ] unit (B) in the polymer chain varies depending on the ratio of the substrates used. The polymer I_a obtained from the 1 : 3 reaction contains these structural units in a 98 : 2 ratio. The polymers are soluble in polar solvents such as DMF (N,N‐dimethylformamide), DMSO (dimethyl sulfoxide), and NMP (N‐methyl‐2‐pyrrolidone) and have molecular weights M_n (M_w) of 4,200–4,800 (4,800–6,500) by GPC (polystyrene standard). The polymerization of the diol and 3,3′‐diaminobenzidine in higher molar ratios leads to partial cross‐linking of the resulting polymers I_e and I_f via condensation of imidazole NH group with CH₂OH group. Similar reactions of 3,3′‐diaminobenzidine with α,ω‐diols, HO(CH₂)_mOH (m = 4–10), in a 1 : 3 molar ratio give the polymers containing [ (CH₂)_m−1 O (CH₂) _m−1 Im ] and [ (CH₂) _m−2 Im ] units with partial cross‐linked structures. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1383–1392, 1999     

Diaminomethylidene derivatives of β-oxo sulfones as potential reagents in heterocyclic synthesis and chelating ligands

Active methylene β-oxo sulfones add to the C≡N bond of benzoylcyanamide in the presence of catalytic amounts of Ni(acac)₂. Debenzoylation of the reaction products under the action of MeONa in MeOH gives N,N′-unsubstituted diaminomethylidene derivatives of β-oxo sulfones (acyl(R-sulfonyl)ketene aminals), which can be used as reagents for heterocyclic synthesis and as chelating ligands. The syntheses of 2-amino-3-arylsulfonylpyridin-4(1H)-ones and 5-sulfonylcytosine derivatives are presented as examples.     

Some reactions of 5-benzyl-2,3,5-trichloro-4,4-dimethoxy-cyclopent-2-en-1-one and its derivatives

5-Benzyl-2,3,5-trichloro-4,4-dimethoxycyclopent-2-en-1-one and 2-benzyl-2,4,5-trichlorocyclopent-4-ene-1,3-dione were subjected to dehydrochlorination by the action of 1,4-diazabicyclo[2.2.2]octane, selective dechlorination at C⁵ by the action of CrCl₂, and Ad_NE replacement of the chlorine atom at C³ by the action of secondary amines. The reduction of 2-benzyl-2,4-dichloro-5-morpholinocyclopent-4-ene-1,3-dione with sodium tetrahydridoborate in methanol and ethanol gave different products.     

Acylation of fluorine-containing spiro[cyclopropane-1-pyrazolines] and dehydrohalogenation of the resulting adducts

Acylation of 6-(1-fluorovinyl)-6-methyl- and 6-(2,2,3,3-tetrafluorocyclobutyl)-4,5-diazaspiro[2.4]hept-4-enes with acetyl chloride proceeds as electrophilic addition to the N(5) atom and is accompanied by opening of the cyclopropane ring to give 1-acetyl-3-(2-chloroethyl)-5-(1-fluorovinyl)-5-methyl- and 1-acetyl-3-(2-chloroethyl)-5-(2,2,3,3-tetrafluorocyclobutyl)-4,5-dihydropyrazoles, respectively. Under the same conditions, acylation of 6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-4-ene is not regioselective. The (2-chloroethyl) pyrazolines obtained undergo dehydrochlorination into vinylpyrazolines in the presence of an excess of MeONa in MeOH. The reaction of 4-acetyl-6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-5-ene with MeONa results in selective replacement of the F atom at the double bond by a methoxy group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 419–422, February, 2005.     

2-酰基-1,3-环二酮类化合物互变异构的理论计算

采用MP2/6-31+G**//B3LYP/6-31+G**方法,系统地研究了2-酰基-1,3-环二酮类化合物的互变异构性质,探讨了环的饱和性、环的大小、环上杂原子以及溶剂效应对各互变异构体相对稳定性的影响。结果表明:(1)未烯醇化的异构体由于无法形成分子内氢键而具有较高的能量;(2)环上杂原子的推电子效应提高了邻位羰基氧上的负电荷,从而有利于相应环外烯醇式异构体的稳定;(3)对化合物3-酰基-1H-吡啶-2,4-二酮,3-酰基吡喃-2,4-二酮,2-酰基环戊-4-烯-1,3-二酮和3-酰基吡咯-2,4-二酮,由互变异构形成的环的芳香性在各异构体的相对稳定性中扮演着决定性的作用。     

Bildung von 5,6-Dihydro-1,3(4H)-thiazin-4-carbonsäure-estern aus 4-Allyl-1,3-thiazol-5(4H)-onen

Formation of Methyl 5,6-Dihydro-l, 3(4H)-thiazine-4-carboxyiates from 4-Allyl-l, 3-thiazol-5(4H)-ones . The reaction of N-[1-(N, N-dimethylthiocarbamoyl)-1-methyl-3-butenyl]benzamid ( 1 ) with HCl or TsOH in MeCN or toluene yields a mixture of 4-allyl-4-methyl-2-phenyl-1,3-thiazol-5(4H)-one ( 5a ) and allyl 4-methyl-2-phenyl-1,3-thiazol-2-yl sulfide ( 11 ; Scheme 3). Most probably, the corresponding 1,3-oxazol-5(4H)-thiones B are intermediates in this reaction. With HCl in MeOH, 1 is transformed into methyl 5,6-dihydro-4,6-dimethyl-2-phenyl-1,3(4H)-thiazine-4-carboxylate ( 12a ). The same product 12a is formed on treatment of the 1,3-thiazol-5(4H)-one 5a with HCl in MeOH (Scheme 4). It is shown that the latter reaction type is common for 4-allyl-substituted 1,3-thiazol-5(4H)-ones.     

The synthesis and characterization of three new vic -dioximes and their nickel(II), copper(II) and cobalt(II) complexes

Three new vic-dioximes, [L¹H₂], N-(4-ethylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, [L²H₂], N-(4-butylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, and [L³H₂], N-(4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II), and Co(II) salts. These new compounds (ligands and complexes) were characterized with FT–IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrometry measurements, thermal methods (e.g. thermal gravimetric analysis), ¹H NMR (Nuclear Magnetic Resonance) and ¹³C NMR spectral data and elemental analyses.     

Synthesis,Characterization and Crystal Structures of Four Dinuclear Schiff Base Nickel(II) and Copper(II) Complexes with Versatile Bridging Groups

Four novel Schiff base nickel(II) and copper(II) complexes, derived from the end‐on (μ_1,1‐N₃) azide, end‐to‐end (μ_1,3‐NCS) thiocyanate, or phenolate oxygen bridges, have been synthesized and their crystal structures determined by X‐ray diffraction methods. They are the dinuclear double end‐on azide‐bridged [Ni₂(L1)₂(MeCN)₂(μ_1,1‐N₃)₂]·MeOH ( 1 ), the dinuclear double end‐on azide‐bridged [Ni₂(L2)₂(MeOH)₂(μ_1,1‐N₃)₂][Ni₂(L2)₂(OH₂)₂(μ_1,1‐N₃)₂]·MeOH ( 2 ), the dinuclear double end‐to‐end thiocyanate‐bridged [Cu₂(L3)₂(μ_1,3‐NCS)₂] ( 3 ), and the dinuclear double phenolate O‐bridged [Cu₂(L4)₂(NCS)₂] ( 4 ), where HL1, HL2, HL3 and HL4 are four tridentate Schiff bases obtained by the condensation of 3,5‐dibromosalicylaldehyde with N‐ethylethane‐1,2‐diamine, of 3,5‐dichlorosalicylaldehyde with N‐methylpropane‐1,3‐diamine, of 3‐bromo‐5‐chlorosalicylaldehyde with 2‐aminomethylpyridine, and of 5‐nitrosalicylaldehyde with 2‐aminomethylpyridine, respectively. Each nickel(II) atom in 1 and 2 is in an octahedral coordination, while each copper(II) atom in 3 and 4 is in a square pyramidal coordination. There exists crystallographic inversion centre symmetry in each of the complexes.     

Isoprene polymerization with indolide‐imine supported rare‐earth metal alkyl and amidinate complexes

Reaction of 7‐{(N‐2,6‐R)iminomethyl)}indole ( HL¹ , R = dimethylphenyl; HL² , R = diisopropylphenyl) and rare‐earth metal tris(alkyl)s, Ln(CH₂SiMe₃)₃(THF)₂, generated new rare‐earth metal bis(alkyl) complexes LLn(CH₂SiMe₃)₂(THF) [L = L¹: Ln = Lu ( 1a ), Sc ( 1b ); L = L²: Ln = Lu ( 3a ), Sc ( 3b )] and mono(alkyl) complexes L²₂Lu(CH₂SiMe₃) ( 4a ). Treatment of alkyl complexes 1a and 4a with N,N′‐diisopropylcarbodiimide afforded the corresponding amidinates L¹Lu{iPr₂NC(CH₂SiMe₃)NiPr₂}₂ ( 2a ) and L²₂Lu{iPr₂NC(CH₂SiMe₃)NiPr₂} ( 5a ), respectively. These new rare‐earth metal alkyls and amidinates except 4a in combination with aluminum alkyls and borate generated efficient homogeneous catalysts for the polymerization of isoprene, providing high cis‐1,4 selectivity and high molar mass polyisoprene with narrow molar mass distribution (M_n = 2.65 × 10⁵, M_w/M_n = 1.07, cis‐1,4 98.2%, −60 °C). The environmental hindrance around central metals arising from the bulkiness of the ligands, the Lewis‐acidity of rare‐earth metal ions, the types of aluminum tris(alkyl)s and borate, and polymerization temperature influenced significantly on both the catalytic activity and the regioselectivity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5251–5262, 2008     

A new vic-dioxime ligand containing two azo substituents and its mononuclear nickel(II), cobalt(II), and copper(II) complexes; synthesis, characterization, spectroscopic and biological studies

A new vicinal dioxime ligand containing azo and thione chromophores, namely 1,3-bis[4-(phenyldiazenyl)phenyl]-2-thiooxaimidazoline-4,5-dione dioxime (bppH₂), was synthesized by the reaction of cyanogen di-N-oxide with N,N′-bis(4-phenylazophenyl) thiourea in dichloromethane solution at −10 °C. Mononuclear complexes of bppH₂ with nickel(II), cobalt(II), and copper(II) were synthesized. The complexes, [Ni(bppH)₂], [Cu(bppH)₂], and [Co(bppH)₂] were characterized by several techniques using elemental analyses, conductivity measurements, FT-IR, and electronic spectral studies. The data suggest that the ligand coordinates through the N,N atoms, as do most vic-dioximes. The molar conductivities in DMF solution indicate nonelectrolytic nature for the complexes. Antimicrobial activities of the ligand and its metal complexes were estimated for five bacteria, namely Klebsiella pneumoniae, Micrococcus luteus, Mycobacterium smegmatis, Enterobacter cloaca and Bacillus megaterium and three fungi, namely Candida albicans, Kluyveromyces marxianus, and Rhodotorula rubra.