Tartrate bridging ligands in divalent Co(II)/Co(III) dinuclear anion

Kozlevčar, Bojan (author), Tihomirović, Maja (author), Počkaj, Marta (author), Jagličić, Zvonko (author)

A cobalt(II/III) ionic compound with bridging tartaric acid ($H_4L$) anion ($CH_6N_3)3[Co_2^{II/III}(L)_2(H_2O)_2]·4H_2O$ 1 was synthesized. The crystallites were isolated from highly alkaline aqueous solution in the presence of guanidinium cations ($CH_6N_3)^+$ being then incorporated as counter ions. A determined structure reveals the dinuclear coordination anion with two cobalt centers, each within its distinctive coordination octahedron $CoO_6$ sphere showing different Co−O bond lengths. The metal center with shorter coordination bonds is assigned as Co(III), while the other with Co(II), all in agreement with overall net charge equilibrium. This involves three guanidinium cations, two tartrate(4-) anions, the latter within the coordination anion, as well as with bond valence sums for both cobalt centers. Both tartrates (L) are triply bonded on the Co(III) center, thus enabling $Co^{III}O_6$ coordination bonds. On the other hand, only two coordination bonds are enabled by each tartrate towards Co(II), while the remaining two in $Co^{II}O_6$ are completed by two terminal water molecules. The electronic spectrum shows clearly the d-d bands at 400 and 665 nm for Co(III), while at 520 nm for Co(II), for each CoO6, respectively. The temperature dependent magnetic susceptibility shows the paramagnetic behavior of the compound, due to the $d^7$ Co(II) ions being in a high spin state, while the $d^6$ low spin Co(III) ions are diamagnetic.

• Language: English
• Keywords: cobalt, tartrate, guanidine, structure, magnetism
• Work type: Abstract or summary
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology; FGG - Faculty of Civil and Geodetic Engineering
• Publication status: Published
• Publication version: Version of Record
• Publication date: 01.01.2024
• Year: 2024
• Number of pages: 11 str.
• Numbering: Vol. , art. 116797
• PID: 20.500.12556/RUL-153183
• UDC: 546.73:547.476.3-38
• ISSN on article: 0277-5387
• DOI: 10.1016/j.poly.2023.116797
• COBISS.SI-ID: 178257155
• Publication date in RUL: 20.12.2023

Record is a part of a journal

• Title: Polyhedron
• Shortened title: Polyhedron
• Publisher: Pergamon Press
• ISSN: 0277-5387
• COBISS.SI-ID: 26153984

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: kobalt, tartrat, gvanidin, struktura, magnetizem

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0175
• Name: Napredna anorganska kemija

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0348
• Name: Nove slikovno-analitske metode