Sac Ligands Research Articles

Metal saccharinate complexes with N,N-bis(2-hydroxyethyl)ethylendiamine: Synthesis, structural, thermal decomposition and DFT studies

New Co(III), Ni(II), Cu(II), and Zn(II) saccharinate (Sac) complexes bearing with N,N-bis(2-hydroxyethyl)ethylenediamine (N-bishydeten), namely [Co(2HN-bishydeten)2](Sac)⋅2H2O, [Ni(Sac)2(N-bishydeten)], [Cu(N-bishydeten)2](Sac)2 and [Zn(Sac)2(N-bishydeten)] were synthesized and characterized using UV–Vis, IR spectroscopy and magnetic susceptibility measurements. The crystal structures of the complexes were analysed by single crystal X-ray diffraction. Both N-bishydeten and Sac displayed coordination versality. The N-bishydeten ligands were octahedrally coordinated as two tridentate anionic ligands (2HN-bishydeten) (N, N, O-) to the Co(III) and two tridentate neutral ligands (N, N, O) to the Cu(II). The anionic Sac ligand was also located outside the coordination sphere in these complexes. However, the N-bishydeten ligand behaved as a tetradentate ligand (O, N, O, N) in the Ni(II) and Zn(II) complexes while two Sac ligands were coordinated the corresponding metals ions in a monodentate fashion, one through the N atom and the other via the carbonyl O atom. Thermal decomposition of the complexes was studied in inert atmosphere and thermal analysis data (TG and DTA) indicated multi-step decompositions of the metal complexes decomposed in a single stage. The thermal decomposition products were estimated as metal oxides. Finally, the structural properties of all complexes were investigated through quantum chemical computations.

Synthesis and structure of rhenium carbonyl complexes bearing a saccharinate ligand

AbstractSaccharin (sacH) reacts with [Re2(CO)8(NCMe)2] at room temperature to afford dinuclear [Re2(CO)8(μ‐H)(μ‐sac‐κN,O)] (1), which contains a bridging sac ligand coordinated to both rhenium centers using the nitrogen and ketonic oxygen atoms, and the mononuclear compounds [Re(CO)5(sac‐κN)] (2) and cis‐[Re(CO)4(NCMe)(sac‐κN)] (3), both of which contain a sac ligand bonded to rhenium using only the nitrogen atom. Complex 3 that contains an MeCN ligand reacts with tri(2‐furyl)phosphine (PFu3) at room temperature to yield cis‐[Re(CO)4(PFu3)(sac‐κN)] (4). The molecular structures of 1–4 have been established by X‐ray crystallography, and the bonding in compound 1 has been examined by electronic structure calculations.

New Copper-Based Metallodrugs with Anti-Invasive Capacity.

While metal-based complexes are deeply investigated as anticancer chemotherapeutic drugs, fewer studies are devoted to their anti-invasive activity. Herein, two copper (Cu)(II) tropolone derivatives, [Cu(Trop)Cl] and [Cu(Trop)Sac], both containing the N,N-chelated 4,4'-bishydroxymethyl-2,2'-bipyridne ligand, were evaluated for their anticancer and anti-invasive properties. RKO (RKO-ctr) colon cancer cells and their derivatives undergoing stable small interference (si) RNA for HIPK2 protein (RKO-siHIPK2) with acquisition of pro-invasive capacity were used. The results demonstrate that while [Cu(Trop)Sac] did not show cytotoxic activity, [Cu(Trop)Cl] induced cell death in both RKO-ctr and RKO-siHIPK2 cells, indicating that structural changes on substituting the coordinated chloride ligand with saccharine (Sac) could be a key factor in suppressing mechanisms of cellular death. On the other hand, both [Cu(Trop)Sac] and [Cu(Trop)Cl] complexes counteracted RKO-siHIPK2 cell migration in the wound healing assay. The synergic effect exerted by the concomitant presence of both tropolone and saccharin ligands in [Cu(Trop)Sac] was also supported by its significant inhibition of RKO-siHIPK2 cell migration compared to the free Sac ligand. These data suggest that the two Cu(II) tropolone derivatives are also interesting candidates to be further tested in in vivo models as an anti-invasive tumor strategy.

Crystal Field Splitting Energy (Δo) and Racah Parameters (B) of Some Metal-Saccharine and Metal-Saccharine-Ethylenediamine Complexes

[M(sac)2(H2O)4].2H2O [sac = saccharinato anion, M = Fe(II), Co(II), Ni(II), and Cu(II)], and [M(sac)2(en)2].2H2O [sac = saccharinato anion, en = ethylenediamine, M = Fe(II), Co(II), Ni(II) and Cu(II)] were prepared in an aqueous medium. The compounds are crystalline of different colors and are ambiently stable. By examining their physico-chemical properties and relevant literature, the metal(II) ions in both [M(sac)2(H2O)4].2H2O and [M(sac)2(en)2].2H2O complexes are octahedrally coordinated. In the former by four neutral H2O molecules and two monoanionic sac ligands while in later, the octahedral sites fulfilled by two neutral bidentate ethylenediamine molecules and two monoanionic sac ligands. Splitting of the crystal field (Δo) and Racah parameter (B) of two sets of complexes [M(sac)2(H2O)4].2H2O and [M(sac)2(en)2].2H2O are estimated from their electronic spectra using Tanabe-Sugano diagram of Co(II) and Ni(II) complexes while Δo values of Fe(II) and Cu(II) derivatives are calculated directly from their absorption maxima. Our experimental results show that for the studied ligands and the divalent transition metal ions, the Δo values vary according to the following order: Cu(II) > Fe(II) > Co(II) > Ni(II). Dhaka Univ. J. Sci. 71(1): 6-12, 2023 (Jan)

Synthesis, characterization and crystal structures of platinum(II) saccharinate complexes with 1,5-cyclooctadiene

Two new platinum(II) complexes, namely [PtCl(sac)(COD)] (1) and [Pt(sac)2(COD)] (2) (sac = saccharinate and COD = 1,5-cyclooctadiene), were synthesized and characterized by elemental analysis, IR, NMR, ESI-MS spectroscopic and thermal analysis (TG/DTA) methods. The platinum(II) complexes were prepared from the reaction of [PtCl2(COD)] with Na(sac)•2H2O. The addition of the sac ligand resulted in the replacement of 1 and 2 chlorido ligands in [PtCl2(COD)] to yield 1 and 2, respectively. The structures of the complexes were determined by single crystal X-ray diffraction and showed a distorted square planar coordination geometry around platinum(II). COD acted as a π-donor ligand, while sac was N -coordinated in both complexes. The TG/DTA data indicated that both complexes were thermally stable up to 220 °C in air and their thermal decompositions yielded Pt as a final product. Complexes 1 and 2 were also designed as possible precursors to synthesize new mixed-ligand platinum(II) sac complexes in a one-pot reaction.

Synthesis, characterization and crystal structures of platinum(II) saccharinate complexes with 1,5-cyclooctadiene.

Two new platinum(II) complexes, namely [PtCl(sac)(COD)] (1) and [Pt(sac)2(COD)] (2) (sac = saccharinate and COD = 1,5-cyclooctadiene), were synthesized and characterized by elemental analysis, IR, NMR, ESI-MS spectroscopic and thermal analysis (TG/DTA) methods. The platinum(II) complexes were prepared from the reaction of [PtCl2(COD)] with Na(sac)•2H2O. The addition of the sac ligand resulted in the replacement of 1 and 2 chlorido ligands in [PtCl2(COD)] to yield 1 and 2, respectively. The structures of the complexes were determined by single crystal X-ray diffraction and showed a distorted square planar coordination geometry around platinum(II). COD acted as a π-donor ligand, while sac was N -coordinated in both complexes. The TG/DTA data indicated that both complexes were thermally stable up to 220 °C in air and their thermal decompositions yielded Pt as a final product. Complexes 1 and 2 were also designed as possible precursors to synthesize new mixed-ligand platinum(II) sac complexes in a one-pot reaction.

Synthesis, structures and catalytic activity of Pd(II) saccharinate complexes with monophosphines in direct arylation of five-membered heteroarenes with aryl bromides

A number of new Pd(II) saccharinate (sac) complexes bearing a range of phenyl (Ph), cyclohexyl (Cy) and alkyl (Me and Et) substituted tertiary phosphine ligands with systematically changing electronic and steric properties, namely trans-[PdCl(sac)(L)2] (L = PPh3 (1); PPh2Cy (3)), trans-[Pd(sac)2(H2O)(L)] (L = PPh3 (2); PPh2Cy (5)), trans-[Pd(sac)2(L)2] (L = PPh2Cy (4); PPhCy2 (6); PCy3 (8)), [PdCl(sac)(PCy3)(DMSO)] (7), trans-[Pd(sac)2(PPh2Me)(DMSO)] (9) and cis-[M(sac)2(L)2] (L = PPhMe2 (10); PPh2Et (11); PPhEt2 (12)), were synthesized and structurally characterized. The Pd(II) complexes were applied for direct C2/C5 arylation of five-membered heteroarenes such as furan, thiophene and thiazole derivatives with aryl bromides. Notably, arylation products up to 99% yields were obtained in the presence of the Pd(II) complexes. The catalytic mechanism of the direct arylation was proposed to proceed via a Pd(0)/Pd(II) pathway, due to elimination of the sac ligand in the Pd(II) complexes during catalysis.

A series of silver(I) coordination polymers with saccarinate and flexible aliphatic diamines

A series of Ag(I) complexes with aliphatic diamines having a different chain length (NH2-(CH2)n-NH2, n=4–9), with the formulas, [Ag(μ-sac)(μ-db)0.5]n (1), {[Ag4(sac)4(μ-dp)2]·4H2O}n (2), {[Ag2(sac)2(μ-dz)]·2H2O}n (3), {[Ag2(sac)2(μ-dh)]·H2O}n (4), {[Ag2(sac)2(μ-do)]·H2O}n (5a), [Ag2(sac)2(μ-do)2] (5b) and [Ag4(sac)4(μ-dn)2]·2H2O (6), where sac=saccharinate, db=1,4-diaminobutane, dp=1,5-diaminopentane, dz=1,6-diaminohexane, dh=1,7-diaminoheptane, do=1,8-diaminooctane and dn=1,9-diaminononane, were synthesized and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction analysis. In 1, the sac ligand bridges adjacent Ag(I) ions through the nitrogen and carbonyl oxygen atoms to form eight-membered bimetallic rings with the Ag···Ag distance being 3.897Å, which are linked by db ligands to give a 1D zigzag chain. The complexes 2–5a consist of a one-dimensional (1D) linear cationic chains and discrete mononuclear anions. The discreet complex units are further connected by ligand unsupported argentophilic interactions. In 6, the dn ligands bridge adjacent silver centers to form 24-membered macrometallacyclic rings, which are further connected to the anionic [Ag(sac)2]- units by argentophilic Ag1···Ag2 interactions to form a tetranuclear structure. The adjacent dinuclear units are further linked together through ligand-unsupported argentophilic Ag···Ag (3.207(1)Å) interactions, generating a one-dimensional linear chain. The most striking feature of complexes is the presence of the rare intermolecular C-H···Ag interactions. In 5b, the do ligand bridges two Ag(I) ions to form a dinuclear with a 22-membered macrometallacyclic ring. Furthermore, biological activities, luminescence properties and thermal analysis (TG/DTA) of the complexes were investigated.

A comparative study of the coordination of saccharinate (sac), thiosaccharinate (tsac) and benzisothiazolinate (bit) ligands to trans-[PdCl2(H2NBz)2]: molecular structure of cis-[Pd(bit)2(H2NBz)2

A comparative study of reactions of saccharinate (sac), thiosaccharinate (tsac) and benzisothiozolinate (bit) with trans-[PdCl2(H2NBz)2] is reported. While in all cases substitution of both chlorides occurs, product types differ for the three closely related ligands. With sodium saccharinate, trans-[Pd(N-sac)2(H2NBz)2] results in which the sac ligands are N-bound. A similar N-bound coordination is observed with sodium benzisothiazolinate, but a crystal structure shows that they adopt a mutual cis arrangement in cis-[Pd(N-bit)2(H2NBz)2]. In contrast, with sodium thiosaccharinate it is proposed that the new ligands adopt an S-bound coordination mode in trans-[Pd(S-tsac)2(H2NBz)2].

Oxidative-addition of the N–H bond of saccharin (sacH) to a triosmium centre: Synthesis, structure and reactivity of Os3(CO)10(μ-H)(μ-sac)

Saccharin (sacH) is a widely-used sweetener and consequently its chemistry has been extensively studied, but here we report a rare example of its reactivity towards a multinuclear metal centre. Lightly-stabilized Os3(CO)10-n(NCMe)n (n = 1, 2) react with sacH to afford Os3(CO)10(μ-H) (μ-sac) (1) in which the sac ligand bridges an osmium–osmium vector via nitrogen and the carbonylic oxygen (μ-N,O). The reactivity of 1 towards monodentate phosphines, PR3 (R = Ph, Th, Fu), has been investigated. Carbonyl substitution affords both mono- and bis-phosphine substituted derivatives Os3(CO)9(PR3) (μ-H) (μ-sac) (2) and Os3(CO)8(PR3)2(μ-H) (μ-sac) (3) respectively. In the mono-substituted derivatives, the phosphine occupies an equatorial position on the osmium that is directly bonded to the carbonylic oxygen of saccharinate, while in the bis-(phosphine) substituted derivatives the second phosphine is bound to the remote osmium also occupying an equatorial site. In all complexes the saccharinate ligand remains in the bidentate N,O coordination mode thus playing a directing spectator role in these reactions.

Structural diversity of lanthanum saccharinates induced by 1,10-phenanthroline: A synthetic and X-ray crystallographic study

Four new lanthanum(III) complexes of formulae [La(sac)3(phen)2(H2O)2]·(phen)(H2O)2 (1), [La(sac)3(phen)2(H2O)2]·(phen) (2), [La(sac)2(phen)(H2O)4]·(sac) (3) and [La(sac)2(phen)2(H2O)3]·(sac)(phen)(H2O) (4) (phen=1,10 phenanthroline, sac=saccharinate) have been synthesised and characterised by single crystal X-ray diffraction, IR, elemental analysis and thermogravimetric analysis. The binding mode of the sac anion was manipulated through the use of phen as structure inducer. In all four complexes the La(III) ion is in a nine-coordinate environment. The structures of 1 and 2 are similar, comprising of three sac anions coordinating in a monodentate fashion through the carbonyl O-atom, two bidentate phen and two water molecules coordinating directly to the same La(III) ion; a third, uncoordinated phen moiety also forms part of the unit cell. In addition, 1 is characterized by the presence of two crystallization water molecules which are absent in 2. In compound 3 the coordination sphere of La(III) is completed by a bidentate chelating sac through the N- and carbonyl O-atoms, a monodentate sac, a bidentate phen and four water ligands; a third, uncoordinated sac is also present in the crystal lattice. Compound 4 contains two bidentate phen, three water ligands and two monodentate O(carbonyl) sac ligands. The presence of three sac anions coordinating to the same lanthanide ion as well as a bidentate N–Ln–O chelating sac, confirmed by single crystal X-ray crystallography, is unprecedented for rare-earth saccharinates.

Di- and polynuclear silver(I) saccharinate complexes of tertiary diphosphane ligands: synthesis, structures, in vitro DNA binding, and antibacterial and anticancer properties

A series of new silver(I) saccharinate (sac) complexes, [Ag2(sac)2(μ-dppm)H2O]·H2O (1), {[Ag2(μ-sac)2(μ-dppe)]·3H2O·CH2Cl2} n (2), [Ag2(μ-sac)2(μ-dppp)] n (3), and [Ag(sac)(μ-dppb)] n (4) [dppm is 1,1-bis(diphenylphosphino)methane, dppe is 1,2-bis(diphenylphosphino)ethane, dppp is 1,3-bis(diphenylphosphino)propane, and dppb is 1,4-bis(diphenylphosphino)butane], have been synthesized and characterized by C, H, N elemental analysis, IR spectroscopy, (1)H NMR, (13)C NMR, and (31)P NMR spectroscopy, electrospray ionization mass spectrometry, and thermogravimetry-differential thermal analysis. Single-crystal X-ray studies show that the diphosphanes act as bridging ligands to yield a dinuclear complex (1) and one-dimensional coordination polymers (2 and 4), whereas the sac ligand adopts a μ2-N/O bridging mode in 2, and is N-coordinated in 1 and 4. The interaction of the silver(I) complexes with fish sperm DNA was investigated using UV-vis spectroscopy, fluorescence spectroscopy, and agarose gel electrophoresis. The binding studies indicate that the silver(I) complexes can interact with fish sperm DNA through intercalation, and complexes 1 and 3 have the highest binding affinity. The gel electrophoresis assay further confirms the binding of the complexes with the pBR322 plasmid DNA. The minimum inhibitory concentrations of the complexes indicate that complex 1 exhibits very high antibacterial activity against standard bacterial strains of Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus, being much higher than those of AgNO3, silver sulfadiazine, ciprofloxacin, and gentamicin. Moreover, complexes 1-3 exhibit very high cytotoxic activity against A549 and MCF-7 cancer cell lines, compared with AgNO3 and cisplatin. The bacterial and cell growth inhibitions of the silver(I) complexes are closely related to their DNA binding affinities.

Platinum and palladium bis(diphenylphosphino)ferrocene (dppf) complexes with heterocyclic N-acetamide ligands: Synthesis and molecular structures of [MCl(sac)(κ2-dppf)] (M = Pt, Pd, sac = saccharinate), [PtCl(ata)(κ2-dppf)] and [Pt(ata)2(κ2-dppf)] (ataH = N-(2-thiazolyl)acetamide)

Room temperature addition of sodium saccharinate, Na(sac), to [MCl2(κ2-dppf)] (M=Pd, Pt; dppf=1,1′-bis(diphenylphosphino)ferrocene) results in the formation of [MCl(sac)(κ2-dppf)] in which the sac ligand is coordinated in a monodentate fashion through nitrogen. All attempts to coordinate a second saccharinate ligand were unsuccessful. In contrast, reaction of [PtCl2(κ2-dppf)] with N-(2-thiazolyl)acetamide (ataH) in the presence of KOH results in successive replacement of both chlorides affording [PtCl(ata)(κ2-dppf)] and [Pt(ata)2(κ2-dppf)]. Crystal structures have determined for all four complexes. In both saccharinate complexes and [PtCl(ata)(κ2-dppf)] the heterocyclic amide ligand is coordinated as expected through the amide-nitrogen. In contrast in Pt(ata)2(κ2-dppf) both ligands are bound through the nitrogen atom of the thiazole ring. In order to understand the adoption of these different ligand binding modes, geometry optimization calculations were carried out on different isomers of both ata complexes. For [PtCl(ata)(κ2-dppf)] an energy difference of 10.5kJmol−1 was found between observed and unobserved isomers, while for [Pt(ata)2(κ2-dppf)] the difference was 9.3kJmol−1. The reasons for the adoption of these different coordination modes are not clear but steric factors are likely to be a major contributory factor.

Two photoluminescent silver(I) saccharinate complexes: The formation of a potassium-oxygen cluster, and Ag ··· π and (O—H) ··· Ag interactions

Abstract Two new Ag(I)-saccharinate complexes, K[Ag(sac)2] · H2O (1) and [Ag(sac)(ina)] · 1.5 H2O (2) (sac = saccharinate and ina = isonicotinamide), have been synthesized and characterized by elemental analyses, IR spectroscopy, thermal analysis and single crystal X-ray diffraction. The silver atoms adopt a linear AgN2 geometry in each case defined by two sac ligands in 1, and one sac and one ina ligand in 2. In 1, the anionic complex units are linked into a two-dimensional array by two potassium atoms, forming an eight-membered bimetallic ring and a K2O10 potassium−oxygen cluster. Complex 2 shows rare (O—H) ··· Ag and (N—H) ··· Ag interactions. The molecules are connected by Ag ··· Csac (η3) interactions involväing the saccharinate-phenyl rings.

Synthesis, crystal structures, spectroscopic and thermal properties of silver(I) saccharinate complexes with N-donor ligands

The synthesis, spectroscopic and thermal properties and X-ray structures of four silver(I) saccharinate complexes with N-donor ligands, [Ag(sac)(edmen)] (1), [Ag(sac)(teten)] (2), [Ag2(sac)2(o-bix)2] (3) and [Ag(sac)(dpa)] (4) (edmen=N-ethyl-N′,N′-dimethylethylenediamine, teten=N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, o-bix=1,2-bis(imidazole-1-ylmethyl)benzene and dpa=2,2′-dipyridylamine) are described. In complex 1, the Ag(I) ion is coordinated by two N atoms from edmen and one N atom from sac ligand, forming a slightly distorted Y-shaped AgN3 arrangement. In complex 2, the Ag(I) is four coordinated by N-bonded sac and tridentate teten ligands, exhibiting a seesaw AgN3O geometry. A crystallographically independent Ag(I) ion in 3 is surrounded with a T-shaped geometry by two N atoms from o-bix ligand and one N atom from one sac ligand, and the Ag⋯Ag separation is 3.338Å. In complex 4, the Ag1 ion is coordinated by three nitrogen atoms from sac and dpa ligands to form a distorted Y-shaped geometry. The dpa ligand behaves as a bidentate ligand, forming a six-membered chelate ring, while the sac ligand is N-coordinated. The most striking feature of complexes 1 and 2 is the presence of both intra- and intermolecular C–H⋯Ag hydrogen-bonding interactions. Crystal packing of complexes is achieved by the hydrogen bonds, intra- and/or intermolecular C–H⋯π, weak π⋯π and Ag⋯π interactions to generate a three-dimensional supramolecular network. The photoluminescence spectrum shows that 4 displays a red-shift emission in the solid state at room temperature.

Bis(propane-1,3-diamine)disaccharinatonickel(II)

In the title complex, [Ni(C7H4NO3S)2(C3H10N2)2] or [Ni(sac)2(pen)2] (sac = saccharinate or 1,1,3-trioxo-2,3-dihydro-1λ6,2-benzothia­zol-2-ide and pen = propane-1,3-diamine), the NiII ion sits on an inversion center, being coordinated by two N atoms of the sac ligands, which occupy trans positions, and four N atoms of the bidentate pen ligands to define a distorted octa­hedral geometry. The pen ligands chelate the metal ion, forming a six-membered ring which adopts a half-chair conformation, while the sac ligands adopt the most common coordination mode. The crystal packing is stabilized by N—H⋯O hydrogen bonds, which form a one-dimensional network along [010]. It is also supported by an N—H⋯S hydrogen bond between the amine group of the pen ligand and the sulfonyl group of the sac ligand.

Bismuth(III) Saccharinate and Thiosaccharinate Complexes and the Effect of Ligand Substitution on Their Activity against Helicobacter pylori

Five bismuth(III) saccharinate and thiosaccharinate complexes, [Ph2Bi(sac)]∞1, [Bi(sac)3]n2, [Ph2Bi(tsac)]∞4, [PhBi(tsac)2]n5, [Bi(tsac)3]n6 (sacH = saccharin, tsacH = thiosaccharin), have been synthesized and fully characterized. The tendency for ligand redistribution in [Ph2Bi(sac)]∞ has been investigated in solution by NMR spectroscopy. The structures of [Ph2Bi(sac)]∞1 and [Ph2Bi(tsac)]∞4 have been confirmed by X-ray crystallography. In Ph2Bi(sac) the sac ligand is bound to a four-coordinate bismuth center via its imino nitrogen atom with an accompanying long-range Bi–O interaction. However, in the structure of [Ph2Bi(tsac)]∞ the ligand is σ-bound through the exocyclic sulfur atom, giving a thiolate complex, confirming the more thiophilic nature of bismuth(III). Both complexes consist of polymeric chain structures with formally four-coordinated bismuth atoms. The complexes were assessed for their activity against H. pylori. The activity is both ligand dependent and sensitive to the degree of ligand substitution. The saccharinate complexes, 1 and 2, show activity comparable with standard tris-carboxylato bismuth(III) compounds, 6.25 μg/mL, while the activity of the thiolato complexes, 4–6, increases dramatically on increasing the number of thiolate groups from one to three (range 50–6.25 μg/mL). Saccharin, thiosaccharin, and BiPh3 were found to be inactive.

Palladium(II) and platinum(II) saccharinate complexes containing pyridine and 3-acetylpyridine: Synthesis, crystal structures, fluorescence and thermal properties

New palladium(II) and platinum(II) complexes of saccharinate (sac), trans-[Pd(py) 2(sac) 2] ( 1), cis-[Pt(py) 2(sac) 2] ( 2), trans-[Pd(3-acpy) 2(sac) 2] ( 3) and cis-[Pt(3-acpy) 2(sac) 2] ( 4) (py = pyridine and 3-acpy = 3-acetylpyridine) have been synthesized. Elemental analysis, UV–Vis, IR, NMR and TG/DTA characterizations have been carried out. The structures of 1– 4 were determined by X-ray diffraction. The palladium(II) and platinum(II) ions are coordinated by two N-bonded sac ligands, and two nitrogen atoms of py or 3-acpy, forming a distorted square-planar geometry. The palladium(II) complexes ( 1 and 3) are trans isomers, while the platinum(II) complexes ( 2 and 4) are cis isomers. The mononuclear species in the solid state are connected by weak intermolecular C–H ⋯ O hydrogen bonds, C–H ⋯ π and π ⋯ π stacking interactions. The platinum(II) complexes show significant fluorescence at the room temperature.

Synthesis, experimental and theoretical characterization of palladium(II) and platinum(II) saccharinate complexes with 2-(2-pyridyl)benzimidazole

New palladium(II) and platinum(II) complexes of saccharinate (sac) with 2-(2-pyridyl)benzimidazole (pybim) have been synthesized and characterized by elemental analysis and spectroscopic techniques. From the experimental studies, these complexes were formulated as [Pd(pybim)(sac) 2] ( 1), and [Pt(pybim)(sac) 2]·4H 2O ( 2). The ground-state geometries of both complexes were optimized using density functional theory (DFT) methods at the B3LYP level. A bidentate pybim ligand together with two N-coordinated sac ligands form the square-planar MN 4 coordination geometry around the palladium(II) and platinum(II) ions. The calculated IR and UV–vis spectral data have been correlated to the experimental results. Thermal analysis data support the molecular structures of both complexes.

Syntheses, Spectroscopic, Structural, Fluorescent and Thermal Properties of Bis(saccharinato)copper(II) Complexes with two Bis(pyridylamine) Ligands

AbstractTwo new copper(II) complexes of saccharinate (sac) with bis(2‐pyridylmethyl)amine (bpma) and N,N′‐bis[1‐(pyridin‐2‐yl)ethylidene]ethane‐1,2‐diamine (bapen), [Cu(bpma)(sac)2]·H2O (1) and [Cu(bapen)(sac)2] (2), were synthesized and characterized by elemental analysis, TG‐DTA, X‐ray diffraction, and UV/Vis and IR spectroscopy, respectively. In 1, the copper(II) ion is coordinated by two N‐bonded sac ligands, and three nitrogen atoms of bpma, in a distorted square‐pyramidal coordination arrangement, whereas the arrangement around the copper ion in 2 is a distorted octahedron with two N‐coordinated sac ligands and a tetradentate bapen ligand. In addition to hydrogen bonding involving the water molecule in 1, the mononuclear species of 1 and 2 are further connected by weak intermolecular C–H···π and C–H···O interactions to form a three‐dimensional network. Both complexes are luminescent at room temperature and their emissions seem to be due to ligand‐based π–π* transitions.