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85 Results Found

  • Communication
  • Open Access
6 Citations
2,856 Views
10 Pages

Searching for Systems with Planar Hexacoordinate Carbons

  • Diego Inostroza,
  • Luis Leyva-Parra,
  • Osvaldo Yañez,
  • José Solar-Encinas,
  • Alejandro Vásquez-Espinal,
  • Maria Luisa Valenzuela and
  • William Tiznado

13 March 2023

Here, we present evidence that the D2h M2C50/2+ (M = Li-K, Be-Ca, Al-In, and Zn) species comprises planar hexacoordinate carbon (phC) structures that exhibit four covalent and two electrostatic interactions. These findings have been made possible usi...

  • Review
  • Open Access
4 Citations
2,402 Views
34 Pages

9 January 2023

The review presents extensive data (from the author’s work and the literature) on the stereochemical structure of functionalized organophosphorus azoles (pyrroles, pyrazoles, imidazoles and benzazoles) and related compounds, using multinuclear...

  • Article
  • Open Access
5 Citations
2,203 Views
11 Pages

17 January 2023

Hypercoordinate transition-metal species are mainly dominated by the 18-valence-electron (18ve) counting. Herein, we report ternary MAl6S6 (M = Ni, Pd, Pt) clusters with the planar hexacoordinate metal (phM) centers, which feature 16ve counting inste...

  • Feature Paper
  • Article
  • Open Access
4 Citations
2,999 Views
18 Pages

29 November 2020

Non-symbiotic hemoglobins AHb1 and AHb2 from Arabidopsis thaliana are hexacoordinate heme-proteins that likely have different biological roles, in view of diverse tissue localization, expression pattern, and ligand binding properties. Herein, we expa...

  • Article
  • Open Access
2 Citations
927 Views
10 Pages

25 August 2025

Phytoglobins (Pgbs) are plant hemoglobin-like proteins with key roles in nitric oxide (NO) scavenging, oxygen sensing, and hypoxic stress responses. Their typical hexacoordination results in unusually high affinities for gaseous ligands such as NO an...

  • Article
  • Open Access
8 Citations
2,517 Views
15 Pages

Oxidative Implications of Substituting a Conserved Cysteine Residue in Sugar Beet Phytoglobin BvPgb 1.2

  • Simon Christensen,
  • Leonard Groth,
  • Nélida Leiva-Eriksson,
  • Maria Nyblom and
  • Leif Bülow

20 August 2022

Phytoglobins (Pgbs) are plant-originating heme proteins of the globin superfamily with varying degrees of hexacoordination. Pgbs have a conserved cysteine residue, the role of which is poorly understood. In this paper, we investigated the functional...

  • Review
  • Open Access
26 Citations
8,560 Views
34 Pages

15 December 2022

The term hypercoordination refers to the extent of the coordination of an element by its normal value. In the hypercoordination sphere, the element can achieve planar and/or non-planar molecular shape. Hence, planar hypercoordinate carbon species vio...

  • Article
  • Open Access
7 Citations
9,744 Views
18 Pages

In the context of our systematic investigations of penta- and hexacoordinate silicon compounds, which included dianionic tri- (O,N,O′; O,N,N′) and tetradentate (O,N,N,O; O,N,N′,O′) chelators, we have now explored silicon coordination chemistry with a...

  • Feature Paper
  • Article
  • Open Access
15 Citations
4,865 Views
31 Pages

Zero-Field Splitting in Hexacoordinate Co(II) Complexes

  • Roman Boča,
  • Cyril Rajnák and
  • Ján Titiš

A collection of 24 hexacoordinate Co(II) complexes was investigated by ab initio CASSCF + NEVPT2 + SOC calculations. In addition to the energies of spin–orbit multiplets (Kramers doublets, KD) their composition of the spins is also analyzed, al...

  • Article
  • Open Access
13 Citations
6,216 Views
12 Pages

8 December 2016

Crystal structures and magnetic properties of polymeric and trinuclear heterobimetallic MnIII···PtII···MnIII coordination compounds, prepared from the Ba[Pt(CN)4] and [Mn(L4A/B)(Cl)] (1a/b) precursor complexes, are reported. The polymeric complex [{M...

  • Short Note
  • Open Access
1,978 Views
5 Pages

8 January 2023

An X-ray diffraction study of a transesterification product of N-methyl-N-(trimethoxysilylmethyl)acetamide by 4,5-dibromobenzene-1,2-diol was carried out. It was established that the coordination polyhedron of the silicon atom in an anionic complex i...

  • Article
  • Open Access
1 Citations
1,913 Views
10 Pages

Spectroelectrochemical and Theoretical Study of [Si(ttpy)2](PF6)4: A Potential Polychromatic Electrochromic Dye

  • Derek M. Peloquin,
  • Askhat N. Bimukhanov,
  • Anuar A. Aldongarov,
  • Jon W. Merkert,
  • Bernadette T. Donovan-Merkert and
  • Thomas A. Schmedake

3 December 2022

Complexes consisting of earth-abundant main group metals such as silicon with polypyridine ligands are of interest for a variety of optical and electronic applications including as electrochromic colorants. Previous spectroelectrochemical studies wit...

  • Article
  • Open Access
2 Citations
2,529 Views
13 Pages

Unusually Fast bis-Histidyl Coordination in a Plant Hemoglobin

  • Stefania Abbruzzetti,
  • Alex J. Barker,
  • Irene Villar,
  • Carmen Pérez-Rontomé,
  • Stefano Bruno,
  • Giulio Cerullo,
  • Cristiano Viappiani and
  • Manuel Becana

The recently identified nonsymbiotic hemoglobin gene MtGlb1-2 of the legume Medicago truncatula possesses unique properties as it generates four alternative splice forms encoding proteins with one or two heme domains. Here we investigate the ligand b...

  • Article
  • Open Access
1 Citations
3,097 Views
23 Pages

5 December 2023

4-Azidopyridine (1) and SiCl4 react with the formation of the hexacoordinate silicon complex SiCl4(4-azidopyridine)2 (2). Upon dissolving in warm chloroform, the complex dissociates into the constituents 1 and SiCl4 and forms back upon cooling. Depen...

  • Article
  • Open Access
5 Citations
4,150 Views
15 Pages

19 September 2022

Hydrated zinc(II) cations, due to their importance in biological systems, are the subject of ongoing research concerning their hydration shell structure and dynamics. Here, ab initio molecular dynamics (AIMD) simulations are used to study solvent exc...

  • Article
  • Open Access
1 Citations
2,697 Views
11 Pages

Two new cobalt(II) complexes with an unsymmetrical bidentate ligand, 2-(1,4,5,6-tetrahydropyrimidin-2-yl)-6-methoxyphenol (H2mthp), were synthesized and crystallographically characterized. Tetra- and hexa-coordinate mononuclear complexes were selecti...

  • Article
  • Open Access
12 Citations
3,847 Views
15 Pages

Trigonally Distorted Hexacoordinate Co(II) Single-Ion Magnets

  • Ivan Nemec,
  • Ondřej F. Fellner,
  • Berenika Indruchová and
  • Radovan Herchel

29 January 2022

By simple reactions involving various cobalt(II) carboxylates (acetate and in situ prepared pivalate and 4-hydroxybenzoate salts) and neocuproine (neo), we were able to prepare three different carboxylate complexes with the general formula [Co(neo)(R...

  • Article
  • Open Access
8 Citations
3,752 Views
11 Pages

An Ab Initio Investigation of the Hydration of Lead(II)

  • Cory C. Pye and
  • Champika Mahesh Gunasekara

3 March 2022

The structure of lead(II) is not well known in aqueous solution. The Hartree–Fock and second order Møller–Plesset levels of theory using the CEP, LANL2, and SDD effective core potentials in combination with their associated basis s...

  • Feature Paper
  • Review
  • Open Access
3 Citations
2,592 Views
22 Pages

23 November 2023

Functional dependence of the axial zero-field splitting parameter D with respect to a properly chosen geometrical parameter (Dstr) in metal complexes is termed the magnetostructural D-correlation. In mononuclear hexacoordinate Ni(II) complexes with t...

  • Article
  • Open Access
2 Citations
2,601 Views
14 Pages

Synthesis, Molecular, and Supramolecular Structures of Two Azide-Bridged Cd(II) and Cu(II) Coordination Polymers

  • Mezna Saleh Altowyan,
  • Eman M. Fathalla,
  • Jörg H. Albering,
  • Assem Barakat,
  • Morsy A. M. Abu-Youssef,
  • Saied M. Soliman and
  • Ahmed M. A. Badr

1 March 2023

Two 1D coordination polymers were synthesized by reaction of two ligands, 2-amino-4-picoline (2A4Pic) and quinoline-6-carboxylic acid (Qu-6-COOH) with two metal (II) nitrate (M = Cd and Cu) in the presence of azide as a linker. The synthesized metal...

  • Communication
  • Open Access
4 Citations
4,257 Views
15 Pages

22 March 2018

A novel hexanuclear Co(II) coordination compound with a nonsymmetrical Salamo-type bisoxime ligandH4L, namely [{Co3(HL)(MeO)(MeOH)2(OAc)2}2]·2MeOH, was prepared and characterized by elemental analyses, UV–vis, IR and fluorescence spectra, and X-ray s...

  • Article
  • Open Access
6 Citations
10,630 Views
7 Pages

31 December 2003

The crystal and molecular structures of [Ni(Im)6](dtp)2 (Im = imidazole, dtp = O,O′-diphenyldithiophosphate) have been determined by X-ray crystallography. It crystallizes in the triclinic system, space group Pī, with cell parameters a = 9.375 (2), b...

  • Article
  • Open Access
2 Citations
2,246 Views
18 Pages

24 August 2023

In this work, the synthesis and structure of an antimony complex with an aromatic, asymmetric tridentate ligand without an Sb-C bond were studied. Ethoxy(2-salicylidenaminophenolato)antimony(III) was studied with NMR, UV-Vis, and IR spectroscopy and...

  • Review
  • Open Access
2 Citations
4,192 Views
24 Pages

28 August 2020

The possibility of carbon tetravalence in geometries other than tetrahedral and of carbon hypervalence has been taken seriously since the 1970s. Computational modeling and subsequent experimental validation have established the existence of molecules...

  • Article
  • Open Access
1 Citations
559 Views
19 Pages

26 September 2025

Class 1 phytoglobins (Pgbs) are known for their multifunctional roles in plant stress responses, with recent studies suggesting broader interactions involving metabolic and transcriptional regulation. Interestingly, glyceraldehyde-3-phosphate dehydro...

  • Article
  • Open Access
6 Citations
3,756 Views
12 Pages

Synthesis, Structure and Electrochemical Properties of Acetamide- and Caprolactam-Containing Silicon Catecholates

  • Eugenia P. Kramarova,
  • Alexander D. Volodin,
  • Vadim V. Negrebetsky,
  • Anastasia D. Shagina,
  • Teimur M. Aliev,
  • Pavel V. Dorovatovskii,
  • Roman A. Novikov,
  • Anna V. Vologzhanina and
  • Alexander A. Korlyukov

10 June 2021

Hexacoordinated heteroligand silicon catecholates, although being prospective as easily soluble compounds with high hydrolytic stability and diverse redox properties, have been insufficiently studied. The transesterification of 1-(trimethoxysilylmeth...

  • Article
  • Open Access
1 Citations
2,209 Views
15 Pages

2 February 2024

The structures and bonding of selected neutral M(CO)6 complexes (M = Sc, Y, La, Lu, Ac and U) have been studied by density functional theory calculations. The calculations revealed the preference for C2v symmetry and low-spin electronic state for mos...

  • Article
  • Open Access
29 Citations
5,412 Views
18 Pages

Tri- and Mono-Nuclear Zinc(II) Complexes Based on Half- and Mono-Salamo Chelating Ligands

  • Xiu-Yan Dong,
  • Lei Gao,
  • Fei Wang,
  • Yang Zhang and
  • Wen-Kui Dong

1 September 2017

Two newly designed complexes, [Zn(L1)(EtOH)] (1) and [{Zn(L2)(OAc)2}2Zn]·CHCl3 (2) derived from salamo and half-salamo chelating ligands (H2L1 and HL2) have been synthesized and characterized by elemental analyses, IR and UV-VIS spectra, fluorescence...

  • Article
  • Open Access
1 Citations
1,510 Views
12 Pages

The First Crystal Structure of an Anti-Geometric Homoleptic Zinc Complex from an Unsymmetric Curcuminoid Ligand

  • Marco A. Obregón Mendoza,
  • Gabriela Marmolejo Escamilla,
  • Rosario Tavera-Hernández,
  • Rubén Sánchez-Obregón,
  • Rubén A. Toscano and
  • Raúl G. Enríquez

24 August 2024

Curcuminoids are widely studied due to their well-recognized therapeutic properties. These molecules are often derivatized with metals, producing their corresponding homoleptic metal complexes. Numerous crystal structures of homoleptic symmetric curc...

  • Article
  • Open Access
4 Citations
2,318 Views
13 Pages

28 June 2023

Recent joint mass spectrometric and IR photodissociation studies have provided proof on the existence of octa-coordinated ionic lanthanide-carbonyl complexes under those extreme gaseous conditions. In contrast, in older literature concerning cryogeni...

  • Article
  • Open Access
1 Citations
2,641 Views
14 Pages

The hexacoordinate Co(II) complex [Co(neo)2(cin)][BPh4]·½Me2CO (1·½Me2CO) containing trans-cinnamic acid (Hcin) and neocuproine (neo) was prepared. The compound 1·½Me2CO was characterized via single-crystal X...

  • Article
  • Open Access
99 Citations
7,387 Views
13 Pages

18 February 2019

A new homo-trinuclear Ni(II) half-salamo-based complex [Ni3(L)2(μ-OAc)2(OAc)2(CH3OH)2]·2CH3OH was synthesized via the reaction of a tridentate ligand HL (2-[O-(1-ethyloxyamide)]oxime-4-bromophenol) and Ni(OAc)2·4H2O, and characterize...

  • Article
  • Open Access
47 Citations
8,044 Views
19 Pages

1 February 2018

Three newly designed complexes, [Cu(L)]·CHCl3 (1), [Co(L)(MeOH)]·CHCl3 (2) and [{Ni(L)(MeOH)(PhCOO)}2Ni] (3) a coumarin-containing Salamo-type chelating ligand (H2L) have been synthesized and characterized by elemental analyses, IR and UV-VIS spectra...

  • Article
  • Open Access
36 Citations
6,980 Views
11 Pages

Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

  • Qiushi Zheng,
  • Yimin Zhang,
  • Tao Liu,
  • Jing Huang,
  • Nannan Xue and
  • Qihua Shi

24 February 2017

Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extra...

  • Article
  • Open Access
1 Citations
1,677 Views
20 Pages

Hell’s Gate globin-I (HGb-I) is a thermally stable globin from the aerobic methanotroph Methylacidiphilium infernorum. Here we report that HGb-I interacts with lipids stoichiometrically to induce structural changes in the heme pocket, changing...

  • Article
  • Open Access
3 Citations
1,984 Views
16 Pages

Synthesis, Crystal Structures, Antimicrobial Activity, and Acute Toxicity Evaluation of Chiral Zn(II) Schiff Base Complexes

  • Daniela Gutiérrez Arguelles,
  • Claudia P. Villamizar,
  • Eduardo Brambila-Colombres,
  • Bertin Anzaldo,
  • Angel Mendoza,
  • Guadalupe Hernández Téllez and
  • Pankaj Sharma

25 November 2024

Four mononuclear bioefficient zinc coordination complexes [Zn(NN)3](ClO4)2 (A–D) involving chiral bidentate Schiff base ligands have been synthesized and characterized by IR, 1H, and 13C NMR spectroscopy and mass spectrometry. X-ray crystal str...

  • Communication
  • Open Access
10 Citations
3,437 Views
13 Pages

18 May 2018

The newly designed butterfly-shaped hetero-tetranuclear CuII-NaI coordination compound, [Cu3(HL)2Na]∙Pic (Pic− is abbreviation of picrate) (1) which is derived from a naphthalenediol-based bis(Salamo)-type chelating ligand H4L have been synthes...

  • Article
  • Open Access
560 Views
30 Pages

Steam-Induced Aluminum Speciation and Catalytic Enhancement in ZSM-5 Zeolites

  • Luigi Madeo,
  • Niels Blom,
  • Finn Joensen,
  • Janos B. Nagy and
  • Pierantonio De Luca

2 December 2025

ZSM-5 zeolites with varying aluminum content were subjected to steam treatments of different severities by adjusting the temperature, duration, and water vapor pressure. The steamed samples were characterized using a range of analytical techniques. A...

  • Article
  • Open Access
45 Citations
5,206 Views
15 Pages

Two unprecedented homometallic CoII and ZnII coordination compounds, [M2(L)(OCH3)][M2(L)(OAc)] (MII = CoII (1) and ZnII (2)), with a novel symmetric bis(salamo)-like tetraoxime ligand H3L were synthesized and characterized by elemental analyses, infr...

  • Article
  • Open Access
1 Citations
2,083 Views
12 Pages

Structural and Optical Characterization of a New Tetra- and Hexa-Coordinated Cd-Based Hybrid Compound with White Light Emission

  • Imen Sayer,
  • Rawia Msalmi,
  • Edoardo Mosconi,
  • Ahlem Guesmi,
  • Ammar Houas,
  • Naoufel Ben Hamadi and
  • Houcine Naïli

12 May 2024

The present paper deals with a new two-in-one zero-dimensional (0D) organic–inorganic hybrid compound namely (C6H10N2)4[CdBr6][CdBr4]2. This molecular crystal structure contains isolated CdBr4 tetrahedra and CdBr6 octahedra. The optical charact...

  • Article
  • Open Access
3 Citations
2,796 Views
13 Pages

26 October 2021

The supramolecular structures of the three metal (II) azido complexes [Fe(4bzpy)4(N3)2]; 1, [Ni(4bzpy)4(N3)2]; 2 and [Zn(4bzpy)2(N3)2]n; 3 with 4-benzoylpyridine (4bzpy) were presented. All complexes contain hexa-coordinated divalent metal ions with...

  • Article
  • Open Access
3 Citations
3,674 Views
18 Pages

Synthesis of Bivalent Ni(II), Cu(II) and Zn(II) Complexes of Azodicarbonamide in Mixture of Methanol and Aqueous Solvents: Spectral Characterizations and Anti-Microbial Studies

  • Ayman A. O. Younes,
  • Abdel Majid A. Adam,
  • Moamen S. Refat,
  • Asma S. Al-Wasidi,
  • Abdulrahman A. Almehizia,
  • Mohamed A. Al-Omar,
  • Ahmed M. Naglah,
  • Abdulrahman M. Al-Obaid,
  • Hamad M. Alkahtani and
  • Kareem A. Asla
  • + 2 authors

21 February 2023

Three new transition-metal complexes were produced by refluxing azodicarbonamide (ADCA) with nickel(II), copper(II), and zinc(II) solutions in a mixture of 50% (v/v) methanol and water. The magnitude of chelation between metal ions and ligand molecul...

  • Article
  • Open Access
718 Views
15 Pages

Mono- and Polynuclear Hg(II) Complexes with Mixed Ligands: Nicotinamide and Oxalate, Nitrate, or Sulphate

  • Laurențiu Pricop,
  • Anamaria Hanganu,
  • Mihaela Ganciarov and
  • Augustin M. Mădălan

25 September 2025

Three new complexes of Hg(II), with the general formulas [Hg2(ox)2(NA)4]n·3nH2O (1), [Hg(NO3)2(NA)2(H2O)2]·2NA (2), and [Hg2(SO4)2(H2O)2(NA)4]·6H2O (3), where ox = oxalate and NA = nicotinamide, were synthesized and characterized...

  • Communication
  • Open Access
6 Citations
2,599 Views
12 Pages

21 January 2021

The crystal structures of two azobenzene derivative Schiff base metal complexes (new C44H40CuN6O2 of P-1 and known C44H38MnN6O7 of P21/c abbreviated as Cu and Mn, respectively) were (re-)determined experimentally using conventional X-ray analysis to...

  • Article
  • Open Access
17 Citations
2,582 Views
10 Pages

Co (II) Complexes Based on the Bis-Pyrazol-S-Triazine Pincer Ligand: Synthesis, X-ray Structure Studies, and Cytotoxic Evaluation

  • Heba M. Refaat,
  • Atallh A. M. Alotaibi,
  • Necmi Dege,
  • Ayman El-Faham and
  • Saied M. Soliman

20 May 2022

Four pincer-type Co (II) complexes of the 2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine ligand (L) were evaluated for their cytotoxic activities against lung and breast cancer cell lines using cell viability assay. The X-ray single...

  • Article
  • Open Access
11 Citations
5,658 Views
16 Pages

Residues in the Distal Heme Pocket of Arabidopsis Non-Symbiotic Hemoglobins: Implication for Nitrite Reductase Activity

  • Nitin Kumar,
  • Alessandra Astegno,
  • Jian Chen,
  • Alejandro Giorgetti and
  • Paola Dominici

It is well-established that plant hemoglobins (Hbs) are involved in nitric oxide (NO) metabolism via NO dioxygenase and/or nitrite reductase activity. The ferrous-deoxy Arabidopsis Hb1 and Hb2 (AHb1 and AHb2) have been shown to reduce nitrite to NO u...

  • Article
  • Open Access
3 Citations
5,156 Views
12 Pages

2 June 2017

The synthesis, single crystal X-ray diffraction (SC-XRD) characterization and Hirshfeld topology analysis of molecular packing of the coordination polymer [Ag2L(H2O)2(ClO4)2]n, where L = 2,4,6-trimorpholino-1,3,5-triazine were discussed. The asymmetr...

  • Short Note
  • Open Access
1 Citations
1,884 Views
8 Pages

4 June 2023

Reaction of 3-aminobenzenesulfonic acid (HL1) with Cu(NO3)2·2.5H2O in H2O/DMF leads to the formation of the new bis(3-aminobenzenesulfonato-κN)-diaqua-bis(dimethylformamide-κO)-copper(II) complex [Cu(L1)2(DMF)2(H2O)2] (1) (HL1 = 3-...

  • Article
  • Open Access
4 Citations
5,855 Views
16 Pages

[Co2(L)Ce(OAc)3(CH3CH2OH)]·1.5CH3OH∙0.5CH2Cl2, a heterotrinuclear Co(II)-Ce(III) bis(salamo)-type complex with a symmetric bi(salamo)-type ligand H4L and an acyclic naphthalenediol moiety, was designed, synthesized and characterized by elemental anal...

  • Article
  • Open Access
1,302 Views
20 Pages

Rare earth elements (Ln: Sm, Eu, Tb, Dy) were complexed with caffeic acid (Caf), a natural phenolic compound, to synthesize novel luminescent complexes with enhanced biological activities. The complexes, formulated as Ln(Caf)3·4H2O, were chara...

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