Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions was performed using density functional theory (DFT). In this study, cyclopropane ring–fused γ‐lactones, which are 5.8 kcal/mol more stable than the corresponding minor enantiomer, are obtained as the major product. The results of the calculations suggest that the enantioselectivity of the Ru(II)‐Pheox–catalyzed intramolecular cyclopropanation reaction is affected by the energy differences between the starting structures 5l and 5i . The reaction pathway was found to be a stepwise mechanism that proceeds through the formation of a metallacyclobutane intermediate. This is the first example of a computational chemical analysis of enantioselective control in an intramolecular carbene‐transfer reaction using C₁‐symmetric catalysts.     

Dirhodium-catalyzed enantioselective C-H insertion of N-(2-benzyloxyethyl)-N-(tert-butyl)diazoacetamide and its application for the synthesis of chiral GABOB

Rh(2)(4S-MEOX)(4) and ethereal solvent are the best catalytic system for the enantioselective intramolecular C-H insertion of N-(2-benzyloxyethyl)-N-(tert-butyl)diazoacetamide 2. The highest enantiomeric excess obtained was 91%. A new route for the asymmetric synthesis of gamma-amino-beta-hydroxybutyric acid (GABOB) has been developed.     

Ruthenium(II) complexes containing asymmetric 2-(pyrazin-2-yl)naphthoimidazole: syntheses, characterization, DNA-binding and photocleavage studies

A novel asymmetric bidentate ligand, 2-(pyrazin-2-yl)naphthoimidazole (PZNI), and its Ru(II) complexes [Ru(bpy)₂(PZNI)]²⁺ (1) and [Ru(phen)₂(PZNI)]²⁺ (2) have been synthesized and characterized by elemental analysis, mass spectra, ¹H NMR, and electronic spectroscopy. The electrochemical behaviors of the novel complexes were studied by cyclic voltammetry. The DNA-binding properties of the complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that the complexes 1 and 2 interact with calf thymus DNA by intercalative mode via the terminal naphthyl ring into the base pairs of DNA. The two Ru(II) complexes have also been found to promote the cleavage of plasmid pBR 322 DNA from the supercoiled form I to the open circular form II upon irradiation.     

Immobilised zinc (II) cyclen complexes as catalytic reagents for phosphodiester hydrolysis

Many hydrolases found in nature have Zn(II) ions at their active site. Artificial hydrolases as alternatives for non-enzymatic hydrolysis were prepared by attaching Zn(II) cyclen complexes with an alcohol pendant to a polymeric support. These modified polymers showed a 10⁴-fold enhanced intrinsic reactivity for the hydrolysis of activated phosphodiesters over the non-catalysed reaction in solution.     

Olefin aziridination by copper(II) complexes: Effect of redox potential on catalytic activity

A series of new copper(II) complexes of four sterically hindering linear tridentate 3N ligands N′-ethyl-N′-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L1), N′-benzyl-N′-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L2), N′-benzyl-N′-(6-methylpyrid-2-yl-methyl)-N,N-dimethylethylenediamine (L3) and N′-benzyl-N′-(quinol-2-ylmethyl)-N,N-dimethylethylenediamine (L4) have been isolated and examined as catalysts for olefin aziridination. The complexes [Cu(L1)Cl₂]·CH₃OH 1, [Cu(L2)Cl₂]·CH₃OH 2, [Cu(L3)Cl₂]·0.5 H₂O 3 and [Cu(L4)Cl₂] 4 have been structurally characterized by X-ray crystallography. In all of them copper(II) adopts a slightly distorted square pyramidal geometry as inferred from the values of trigonality index (τ) for them (τ: 1, 0.02; 2, 0.01; 3, 0.07; 4, 0.01). Electronic and EPR spectral studies reveal that the complexes retain square-based geometry in solution also. The complexes undergo quasireversible Cu(II)/Cu(I) redox behavior (E_1/2, −0.272 − −0.454 V) in acetonitrile solution. The ability of the complexes to mediate nitrene transfer from PhINTs and chloramine-T trihydrate to olefins to form N-tosylaziridines has been studied. The complexes 3 and 4 catalyze the aziridination of styrene very slowly yielding above 80% of the desired product. They also catalyze the aziridination of the less reactive olefins like cyclooctene and n-hexene but with lower yields (30-50%). In contrast to these two complexes, 1 and 2 fail to catalyze the aziridination of olefins in the presence of both the nitrene sources. All these observations have been rationalized based on the Cu(II)/Cu(I) redox potentials of the catalysts.     

Structural, magnetic, electrochemical, catalytic, DNA binding and cleavage studies of new macrocyclic binuclear copper(II) complexes

The macrocyclic symmetrical and a series of unsymmetrical binuclear copper(II) complexes have been synthesized by using mononuclear complex [CuL] [3,3′-((1E,7E)-3,6-dioxa-2,7-diazaocta-1,7-diene-1,8-diyl)bis(3-formyl-5-methyl-2-diolato)copper(II)]. Another compartment of the [CuL] have been condensed with various diamines like 1,2-bis(aminooxy)ethane (L¹), 1,2-diamino ethane(L^2a), 1,3-diamino propane(L^2b), 1,4-diamino butane(L^2c), 1,2-diamino benzene(L^2d), 1,8-diamino naphthalene(L^2e) and characterized by elemental, spectroscopic, and X-ray crystallographic methods. The influence of the coordination geometry and the ring size of the binucleating ligands on the electronic, redox, magnetic, catecholase activity, DNA binding and cleavage properties have been studied. The molecular structures of the symmetrical binuclear complex [Cu₂L¹(H₂O)₂](ClO₄)₂ (1) and unsymmetrical binuclear complex [Cu₂L^2b(ClO₄)(H₂O)]ClO₄ (2b) were determined by X-ray crystallography. Both of them were discrete binuclear species in which each Cu(II) ions are in distorted square pyramid. The Cu?Cu distances vary from 3.0308 (2b) to 3.0361 Å (1). Electrochemical studies evidenced that two quasi-reversible one electron-transfer reduction waves −0.91 to −1.01 V, −1.26 to −1.55 V) for binuclear complexes are obtained in the cathodic region. Cryomagnetic investigation of the binuclear complexes reveals a weak antiferromagnetic spin exchange interaction between the Cu(II) ions within the complexes (−2J = 104.4-127.5 cm⁻¹). The initial rate (V_in) for the oxidation of 3,5-di-tert-butylcatechol to o-quinone by the binuclear Cu(II)complexes are in the range 3.6 × 10⁻⁵ to 7.3 × 10⁻⁵ Ms⁻¹. The binuclear Cu(II) complexes are avid binders to calf thymus DNA. The complexes display significant oxidative cleavage of circular plasmid pBR322 DNA in the presence of mercaptoethanol using the singlet oxygen as a reactive species. The aromatic diamine condensed macrocyclic ligands of copper(II) complexes display better DNA interaction and significant chemical nuclease activity than the aliphatic diamine condensed macrocyclic Cu(II) complexes.     

Bis-N-heterocyclic carbene ruthenium(II) carbonyl complexes: Synthesis, structural characterization and catalytic activities in transfer hydrogenation of ketones

In this contribution, the synthesis and characterization of eight ruthenium(II) carbonyl complexes supported by chelating alkane-bridged bis-N-heterocyclic carbene ligands are reported. The products obtained are analyzed using infrared and NMR spectroscopies. The molecular structures of four metal complexes were determined by X-ray crystallography, which exhibit the six-coordinate octahedral geometry with two carbene carbon atoms from the bidentate Bi-NHCs, two carbonyl groups and two chlorine atoms in the trans(Cl)-cis(CO) configuration. All these complexes show catalytic activities in transfer hydrogenation of ketones.     

Structure and characterization of platinum(II) and platinum(IV) complexes with protonated nucleobase ligands

The reaction of H₂[PtCl₆] · 6H₂O and (H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O (18C6 = 18-crown-6) with 9-methylguanine (MeGua) proceeded with the protonation of MeGua forming 9-methylguaninium hexachloroplatinate(IV) dihydrate (MeGuaH)₂[PtCl₆] · 2H₂O (1).The same compound was obtained from the reaction of Na₂[PtCl₆] with (MeGuaH)Cl.On the other hand, the reaction of guanosine (Guo) with (H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O in methanol at 60 °C proceeded with the cleavage of the glycosidic linkage and with ligand substitution to give a guaninium complex of platinum(IV), [PtCl₅(GuaH)] · 1.5(18C6) · H₂O (2).Within several weeks in aqueous solution a slow reduction took place yielding the analogous guaninium platinum(II) complex, [PtCl₃(GuaH)] · (18C6) · 2Me₂CO (3).H₂[PtCl₆] · 6H₂O and guanosine was found to react in water, yielding (GuoH)₂[PtCl₆] (4) and in ethanol at 50 °C, yielding [PtCl₅(GuoH)] · 3H₂O (5).Dissolution of complexes 2 and 5 in DMSO resulted in the substitution of the guaninium and guanosinium ligands, respectively, by DMSO forming [PtCl₅(DMSO)]⁻.Reactions of 1-methylcytosine (MeCyt) and cytidine (Cyd) with H₂[PtCl₆] · 6H₂O and(H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O resulted in the formation of hexachloroplatinates with N3 protonated pyrimidine bases as cation (MeCytH)₂[PtCl₆] · 2H₂O (6) and (CydH)₂[PtCl₆] (7), respectively. Identities of all complexes were confirmed by ¹H, ¹³C and ¹⁹⁵Pt NMR spectroscopic investigations, revealing coordination of GuoH⁺ in complex 5 through N7 whereas GuaH⁺ in complex 3 may be coordinated through N7 or through N9. Solid state structure of hexachloroplatinate 1 exhibited base pairing of the cations yielding (MeGuaH⁺)₂, whereas in complex 6 non-base-paired MeCytH⁺ cations were found. In both complexes, a network of hydrogen bonds including the water molecules was found. X-ray diffraction analysis of complex 3 exhibited a guaninium ligand that is coordinated through N9 to platinum and protonated at N1, N3 and N7. In the crystal, these NH groups form hydrogen bonds N–HO to oxygen atoms of crown ether molecules.     

Antimicrobial metal-based thiophene derived compounds

A novel series of thiophene derived Schiff bases and their transition metal- [Co(II), Cu(II), Zn(II), Ni(II)] based compounds are reported. The Schiff bases act as tridentate ligands toward metal ions via azomethine-N, deprotonated-N of ammine substituents and S-atom of thienyl moiety. The synthesized ligands along with their metal complexes were screened for their in vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and for antifungal activity against six fungal pathogens (Trichophytonlongifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata). The results of antimicrobial studies revealed the free ligands to possess potential activity which significantly increased upon chelation.     

Mn(II) coordination architectures with mixed ligands of 3-(2-pyridyl)pyrazole and carboxylic acids bearing different secondary coordination donors and pendant skeletons

In our efforts to investigate the factors that affect the formation of coordination architectures, such as secondary coordination donors and pendant skeletons of the carboxylic acid ligands, as well as H-bonding and other weak interactions, two kinds of ligands: (a) 3-(2-pyridyl)pyrazole (L¹) with a non-coordinated N atom as a H-bonding donor, a 2,2′-bipyridyl-like chelating ligand, and (b) four carboxylic ligands with different secondary coordination donors and/or pendant skeletons, 1,4-benzenedicarboxylic acid (H₂L²), 4-sulfobenzoic acid (H₂L³), quinoline-4-carboxylic acid (HL⁴) and fumaric acid (H₂L⁵), have been selected to react with Mn(II) salts, and five new complexes, [Mn(L¹)₂(SO₄)]₂ (1), [Mn(L¹)₂(L²)]_∞ (2), [Mn(L¹)(HL³)₂]_∞ (3), Mn(L¹)₂(L⁴)₂ (4), and [Mn(L¹)₂(L⁵)]_∞ (5), have been obtained and structurally characterized. The structural differences of 1-5 can be attributed to the introduction of the different carboxylic acid ligands (H₂L², H₂L³, HL⁴, and H₂L⁵) with different secondary coordination donors and pendant skeletons, respectively. This result also reveals that the typical H-bonding (i.e. N-H?O and O-H?O) and some other intra- or inter-molecular weak interactions, such as C-H?O weak H-bonding and π?π interactions, often play important roles in the formation of supramolecular aggregates, especially in the aspect of linking the multi-nuclear discrete subunits or low-dimensional entities into high-dimensional supramolecular networks.     

Density functional studies on copper-catalysed asymmetric aziridination of diazoacetate with imines

Density functional theory has been used to study copper(I)-catalysed aziridination of diazoacetate with imines. All the intermediates and the transition states were optimised completely at B3LYP/6-31G(d) level. Calculation results confirm that copper(I)-catalysed aziridination of diazoacetate with imines is exothermic, and the total released Gibbs free energy is about ? 170 kJ/mol. Copper(I)-catalysed aziridination has two reaction modes: I and II, and thus the reaction mode I is dominant. The formation of the copper(I)–carbene–imine complex M3 (i.e. the attack of imines on copper–carbon(carbene) of copper–carbene intermediate M2) is the rate-determining step and the chirality-limiting step for copper-catalysed asymmetric aziridination. The reaction channel CA2 → M1a → TS1a → M2 → TS2a2 → M3a2 → TS3a2 → M4a2 → P1 is the most favourable one. The dominant products predicted theoretically are of (R)-chirality.     

Synthesis, X-ray crystal structure and NMR characterisation of mononuclear Pd(II) and Pt(II) complexes of didentate ligands with NN′-donor set

Two new 3,5-dimethylpyrazolic derived ligands that are N1-substituted by diamine chains, 1-[2-(diethylamino)ethyl]-3,5-dimethylpyrazole (L1) and 1-[2-(dioctylamino)ethyl]-3,5-dimethylpyrazole (L2) were synthesised. Reaction of the ligands, L1 and L2, with [MCl₂(CH₃CN)₂] yielded [MCl₂(L)] (M = Pd(II), Pt(II)) complexes. These complexes were characterised by elemental analyses, conductivity measurements, IR, ¹H, ¹³C{¹H} and ¹⁹⁵Pt{¹H} NMR spectroscopies. The crystal structure of [PdCl₂(L1)] was determined by single-crystal X-ray diffraction methods. The structure consists of mononuclear units. The Pd(II) atom is coordinated by a pyrazolic nitrogen, an amine nitrogen and two chlorine atoms in a cis disposition. In this structure, C-H?Cl, C-H?H-C and C-H?C-H intermolecular interactions have been identified.     

Zinc(II) and mercury(II) coordination architectures with two pyridyl/benzimidazol-1-yl-based ligands: Crystal structures and photoluminescent properties

In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related ligands, 1-(2-pyridylmethyl)-1H-benzimidazole (L¹) and 1-(4-pyridylmethyl)-1H-benzimidazole (L²), and their four complexes, [Zn(L¹)₂Cl₂] (1), [Hg(L¹)Br₂]_∞ (2), {[Zn(L²)Cl₂](CH₃CN)}_∞ (3) and [Hg(L²)Br₂]₂(CH₃CN)₂ (4) were synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction analysis. Structural analyses show that 1 has a mononuclear structure, and 2 and 3 both take 1D structure. While 4 takes a dinuclear structure. 1, 2 and 4 were further linked into higher-dimensional supramolecular networks by weak interactions, such as C-H?Cl and C-H?Br H-bonding, C-H?π, and π?π stacking interactions. The structural differences of 1-4 may be attributed to the difference of the spatial positions of the terminal N donor atoms in the pendant pyridyl groups in L¹ and L², in which the pyridine rings may act as the directing group for coordination and the benzimidazole rings act as the directing group for π?π stacking and C-H?π interactions. The luminescent properties of the corresponding complexes and ligands have been further investigated.     

Synthesis and Chiral Recognition of Nickel(II) Macrocyclic Complex with (R)‐Naphthylethyleneamine Pendant Groups and its Self‐Assembled Framework

A novel nickel(II) hexaaza macrocyclic complex, [Ni(L^R,R)](ClO₄)₂ ( 1 ), containing chiral pendant groups was synthesized by an efficient one‐pot template condensation and characterized (L^R,R═1,8‐di((R)‐α‐methylnaphthyl)‐1,3,6,8,10,13‐hexaazacyclotetradecane). The crystal structure of compound 1 was determined by single‐crystal X‐ray analysis. The complex was found to have a square‐planar coordination environment for the nickel(II) ion. Open framework [Ni(L^R,R)]₃[C₆H₃(COO)₃]₂ ( 2 ) was constructed from the self‐assembly of compound 1 with deprotonated 1,3,5‐benzenetricarboxylic acid, BTC^3?. Chiral discrimination of rac‐1,1′‐bi‐2‐naphthol and rac‐2,2,2‐trifluoro‐1‐(9‐anthryl)ethanol was performed to determine the chiral recognition ability of the chiral complex ( 1 ) and its self‐assembled framework ( 2 ). Binaphthol showed a good chiral discrimination on the framework ( 2 ). The optimum experimental conditions for the chiral discrimination were examined by changing the weight ratio between the macrocyclic complex 1 or self‐assembled framework 2 and racemates. The detailed synthetic procedures, spectroscopic data including single‐crystal X‐ray analysis, and the results of the chiral recognition for the compounds are described. Chirality, 25:54‐58, 2013 © 2012 Wiley Periodicals, Inc.     

Synthesis and characterization of Pt(II) and Pt(II)/Ru(II) complexes with the bidentate bridging ligand dipyrido(2,3-a:3′,2′-h)phenazine (dpop)

Three new complexes [Pt(dpop)(Cl)₂], [(Cl)₂Pt(dpop)Pt(Cl)₂] and [(bpy)₂Ru(dpop)Pt(Cl)₂](PF₆)₂ (dpop = dipyrido(2,3-a:3′,2′-h)phenazine) were prepared and studied. The electronic absorption spectra of the complexes display Pt dπ → dpop π* and Ru dπ → dpop π* MLCT transitions at longer wavelengths than for previously reported similar complexes. Results of cyclic voltammograms show reversible dpop centered reductions while for the mixed metal [(bpy)₂Ru(dpop)Pt(Cl)₂]²⁺ an irreversible Pt(II) oxidative wave precedes the Ru(II) oxidation/reduction couple. Spectroelectrochemical results show that all oxidative and reductive processes are completely reversible. The [(Cl)₂Pt(dpop)Pt(Cl)₂] complex cleaves in solution with pseudo-first order kinetics resulting in loss of the Pt dπ → dpop π* MLCT transition at 545 nm.     

Effect of substituents on the configurational stability of the stereogenic nitrogen in metal(II) complexes of α‐amino acid Schiff bases

Herein, we report a general method for quantitative measurement of the configurational stability of the stereogenic nitrogen coordinated to M (II) in the corresponding square planar complexes. This stereochemical approach is quite sensitive to steric and electronic effects of the substituents and shown to work well for Ni(II), Pd(II), and Cu(II) complexes. Structural simplicity of the compounds used, coupled with high sensitivity and reliability of experimental procedures, bodes well for application of this approach in evaluation of chemical stability and stereochemical properties of newly designed chiral ligands for general asymmetric synthesis of tailor‐made amino acids.     

Chiral enamines derived from 2-(2′-pyrido)acetophenone and 2-(2′-quinolino)acetophenone as ligands in copper(I) catalyzed enantioselective cyclopropanations

Optically active enamines of 2-(2′-pyrido)acetophenone or 2-(2′-quinolino)acetophenone with (R)-1-phenylethylamine, (R)-1-(1-naphthyl)ethylamine, (R)-cyclohexylethylamine, and (R)-phenylglycinol were prepared and their copper(I) complexes used in the enantioselective cyclopropanation of styrene with ethyl- and menthyldiazoacetate. Enantioselectivities of up to 42% enantiomeric excess were obtained for cis/trans 2-phenylcyclopropan-1-carboxylic acid ethyl esters, as determined by gas-liquid chromatography (GLC) on chiral chromatographic columns. © 1995 Wiley-Liss, Inc.     

Mercury complexes with the ligand benzaldehyde-N(4),N(4)-dimethylthiosemicarbazone

The Schiff base benzaldehyde-N(4),N(4)-dimethylthiosemicarbazone (LH) and its complexes [Hg(NO₃)(LH)₂]NO₃ (1), [Hg(L)₂] (2), [Hg(LH)₂(μ-X)₂HgX₂] [X = Cl (3), Br (4)], [HgI(LH)(μ-I)₂HgI(LH)] (5) and [HgI₂(LH)] (6) have been synthesized and characterized by IR, mass spectrometry, ¹H and ¹³C NMR and by single crystal X-ray diffraction. All the complexes were obtained in ethanol and complex 2, in which the ligand is deprotonated, in addition needs the presence of basic medium. From mercury(II) iodide two complexes with the same molar ratio but with different structures were isolated. In all the complexes the ligand acts as a NS chelate, except in complex 5 in which is only S-donor. The coordination number of the mercury ion and the structures of the complexes depend on the counterion. Complexes 1, 2 and 6 are monomeric species but with different coordination spheres: N₂S₂O₂ with a distorted octahedral arrangement in complex 1, and N₂S₂ or NSI₂ in a pseudo-tetrahedral geometry in complexes 2 and 6, respectively. However, 3, 4 and 5 are binuclear complexes with two halido bridges, but they show two different structures. In 3 and 4, each mercury ion has a different environment giving an asymmetric structure, one is bonded to two NS-ligands and two halido bridges in a distorted octahedral geometry, and the other one has a tetrahedral environment formed by four halido ligands. In complex 5 both mercury ions are equivalent with a SI₃ distorted tetrahedral coordination sphere, formed by one S-bonded ligand, one terminal iodido and two iodido bridges.     

Synthesis and in vitro antitumoral activity of novel O,O'-di-2-alkyl-(S,S)-ethylenediamine-N,N'-di-2-propanoate ligands and corresponding platinum(II/IV) complexes

Syntheses of two novel ligand precursors O,O'-diisopropyl- (1a) and O,O'-diisobutyl-(S,S)-ethylenediamine-N,N'-di-2-propanoate dihydrochloride monohydrate (1b) and the corresponding dichloroplatinum(II) (2a and 2b) and tetrachloroplatinum(IV) complexes (3a and 3b) are described here. The substances were characterized by IR, (1)H and (13)C spectroscopy and elemental analysis. Crystal structures were determined for 1a and the corresponding platinum(IV) complex, 3a. In vitro antiproliferative activity was determined against tumor cell lines: human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, rested and stimulated normal immunocompetent cells (human peripheral blood mononuclear PBMC cells) using KBR test (Kenacid Blue Dye binding test). The IC(50)(microM) values for the most active compound 3a were: 30.48+/-2.54; 12.26+/-2.60; 13.68+/-3.22; 80.18+/-24.07 and 71.30+/-21.70, respectively.     

Structural variability in manganese(II) complexes of N,N′-bis(2-pyridinylmethylene) ethane (and propane) diamine ligands

Manganese(II) complexes, Mn₂L¹₃(ClO₄)₄, MnL¹(H₂O)₂(ClO₄)₂, MnL²(H₂O)₂(ClO₄)₂, and {(μ-Cl)MnL²(PF₆)}₂ based on N,N′-bis(2-pyridinylmethylene) ethanediamine (L¹) and N,N′-bis(2-pyridinylmethylene) propanediamine (L²) ligands have been prepared and characterized. The single crystal X-ray diffraction analysis of Mn₂L²₃(ClO₄)₄ shows that each of the two Mn(II) ion centers with a Mn-Mn distance of 7.15 Å are coordinated by one ligand while a common third ligand bridges the metal centers. Solid-state magnetic susceptibility measurements as well as DFT calculations confirm that each of the manganese centers is high-spin S = 5/2. The electronic structure obtained shows no orbital overlap between the Mn(II) centers indicating that the observed weak antiferromagentism is a result of through space interactions between the two Mn(II) centers. Under different reaction conditions, L¹ and Mn(II) yielded a one-dimensional polymer, MnL¹(H₂O)₂(ClO₄)₂. Ligand L² when reacted with manganese(II) perchlorate gives contrarily to L¹ mononuclear MnL²(H₂O)₂(ClO₄)₂ complex. The analysis of the structural properties of the MnL²(H₂O)₂(ClO₄)₂ lead to the design of dinuclear complex {(μ-Cl)MnL²(PF₆)} where two chlorine atoms were utilized as bridging moieties. This complex has a rhomboidal Mn₂Cl₂ core with a Mn-Mn distance of 3.726 Å. At room temperature {(μ-Cl)MnL²(PF₆)} is ferromagnetic with observed μ_eff = 4.04 μ_B per Mn(II) ion. With cooling, μ_eff grows reaching 4.81 μ_B per Mn(II) ion at 8 K, and then undergoes ferromagnetic-to-antiferromagnetic phase transition.