Sinteza in karakterizacija bakrovih, nikljevih in kobaltovih spojin z anioni citronske kisline

Cotman, Klemen (author), Kozlevčar, Bojan (mentor)

Pripravili smo šest koordinacijskih spojin z vezano citronsko kislino (H4L = C6H8O7) oziroma bolj natančno z enim od njenih anionov (po dve kobaltovi(II), nikljevi(II) in bakrovi(II)): (C(NH2)3)8[Co4L4]·8H2O 1, Na2[Co2(HL)2(H2O)4]·6H2O 2, (C(NH2)3)8[Ni4L4]·8H2O 3, Na2[Ni2(HL)2(H2O)4]·6H2O 4, [Cu2L(H2O)]n 5, in bakrovi(II) spojini 6, kateri nismo uspeli določiti formule. Sinteze so bile izvedene s preprostimi kovinskimi izhodnimi spojinami, natrijevim citratom(3-) in vse v vodi. Spojine 1, 2, 3 in 5 so bile že opisane v literaturi, kar smo potrdili z rentgensko difrakcijsko analizo. S tako analizo smo tudi potrdili izostrukturnost spojin 1 in 2 s spojinama 3 in 4. Za spojini 4 in 5 se rezultati CHN elementne analize dobro ujemajo z izračunanimi vrednostmi predlaganih formul spojin. Posledično lahko sklepamo, da so bili sintezni produkti spojin 4 in 5 čiste snovi. Rezultati spojin 1 in 3 se ujemajo slabše, kar kaže na prisotnost nečistoč. Takšna elementna analiza za 2 in 6 ni omogočala neke povezave z določeno formulo. Z infrardečo spektroskopijo smo potrdili vezavo citratnih anionov v naše koordinacijske spojine in vezavo gvanidinskega kationa v spojine 1, 3 in 6. Izrazita podobnost IR spektrov je opazna za izostrukturna para spojin 1 in 3 z gvanidinijevim kationom ter 2 in 4 brez tega kationa. Spektra bakrovih spojin 5 in 6 se delno ujemata: 6 z gvanidinijevima spojinam in 5 z ostalima dvema. Razlike, opazne pri UV-Vis spektrih oziroma pri barvah spojin, kažejo na prisotnost različnega centralnega kovinskega(II) iona (Co 1/2, Ni 3/4 in Cu 5/6). Za spojine 1, 2 in 4 se izmerjeni efektivni magnetni moment dobro ujema s pričakovanimi vrednostimi za spojine z ustreznim kovinskim ionom. Meritve za spojine 3, 5 in 6 pa se le delno ujemajo s pričakovanimi vrednostimi. Znižana vrednost za te spojine je lahko posledica antiferomagnetne interakcije ali vprašljive čistosti vzorca.

• Language: Slovenian
• Keywords: koordinacijska spojina, kobalt, nikelj, baker, citrat
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2021
• PID: 20.500.12556/RUL-131933
• COBISS.SI-ID: 87719171
• Publication date in RUL: 06.10.2021

Secondary language

• Language: English
• Title: Synthesis and characterization of copper, nickel and cobalt compounds with citric acid anions

Abstract

Six coordination compounds with citric acid (H4L = C6H8O7) or more preciselly with one of its anions were synthesized (two per cobalt(II), nickel(II) and copper(II)): (C(NH2)3)8[Co4L4]·8H2O 1, Na2[Co2(HL)2(H2O)4]·6H2O 2, (C(NH2)3)8[Ni4L4]·8H2O 3, Na2[Ni2(HL)2(H2O)4]·6H2O 4, [Cu2L(H2O)]n 5 and a copper compound with an undetermined formula. Syntheses were performed with simple metal starting compounds, sodium citrate(3-) and all in water. Compounds 1, 2, 3 and 5 were already described in the literature, which we confirmed with X-ray diffraction analysis. Compounds 1 and 2 are isostructural to 3 and 4, respectively. The results of CHN elemental analysis for the compounds 4 and 5 are in agreement with the calculated values of proposed compound formulaes. It can therefore be concluded, that compounds 4 and 5 are pure substances. This type of data for compounds 1 and 3 does not show such agreement, therefore indicating the presence of impurities. For compounds 2 and 6 elemental analysis did not allow correlation with a formula. The CHN elemental analysis results of the compound Citrate anions bonding into all our investigated coordination compounds, as well as guanidine cations bonding into compounds 1, 3 and 6, were confirmed with infrared spectroscopy. IR spectra of isostructural pairs 1 and 3 with guanidinium cation and 2 and 4 without this cation are very similar. IR spectra of 5 amd 6 match partialy: 6 with the guanidinium pair and 5 with the other pair. The UV-Vis spectras well as the color of the six compounds differ due to different central metal cation present (Co 1/2, Ni 3/4 in Cu 5/6). The measured effective magnetic moment of compounds 1, 2 and 4 matches well with expected values for their corresponding metal cations. For compounds 3, 5 and 6 the measurements only match partially with their expected values. The low value of effective magnetic moment for these compounds can be explained with the antiferromagnetic effect or questionable purity.

• Keywords: coordination compound, cobalt, nickel, copper, citrate