Synthesis and characterisation of Co(III) polyoxomolybdate salts

U ovom diplomskom radu ispitivane su reakcije natrijeva molibdata dihidrata (NaMoO4·2H2O) s kompleksnom soli [CoCO3(NH3)4]NO3 uz zakiseljavanje s oksalnom ili klorovodičnom kiselinom. Reakcije su izvedene u otopini na sobnoj temperaturi i hidrotermalno pri 110 ̊C u trajanju od 1,5 h. Produkti su karakterizirani pomoću rentgenske difrakcije, IR spektroskopije, termogravimetrijske i kemijske analize. U reakcijama s klorovodičnom kiselinom dobivena je smjesa praškastih produkata. Reakcije s oksalnom kiselinom dale su tri kristalna produkata, pri čemu su dva bila kompleksne soli kobalta i polioksomolibdata, a treći je bila sol Co(II)/Co(III). Zaključeno je da su stehiometrijski omjer i koncetracije reaktanata, ali i pH ključni faktori pri nastajanju dotičnih produkata. Izolirani su i karakterizirani slijedeći produkti: 3Na[CoC2O4(NH3)4][Mo2O4(μ-O)2(C2O4)2], [CoC2O4(NH3)4]4[Mo3O6(μ-O)2(C2O4)3(H2O)2]·nH2O i [CoIIIC2O4(NH3)4]2[CoII(C2O4)2(H2O)2]·4H2O.In this diploma thesis the reactions of sodium molybdate dihydrate (Na2MoO4·2H2O) with a complex salt [CoCO3(NH3)4]NO3 acidified with oxalic or hydrochloric acid were investigated. Reactions were performed in solution at room temperature and hydrothermally at 110 ̊C in duration of 1,5 h. Products were characterised with X-ray diffraction, IR spectroscopy, thermogravimetric and chemical analysis. Reactions with hydrochloric acid yielded a mixture of amorphous products. Reactions with oxalic acid have yielded three crystalline products, two of which were complex salts of cobalt and polyoxomolybdate and the third was complex salt of cobalt(II)/(III). It was concluded that the stechiometric ratio and the concentration of the reactants, along with pH are the key factors in producing these products. Following products were isolated and characterised: 3Na[CoC2O4(NH3)4][Mo2O4(μ-O)2(C2O4)2], [CoC2O4(NH3)4]4[Mo3O6(μ-O)2(C2O4)3(H2O)2]·nH2O i [CoIIIC2O4(NH3)4]2[CoII(C2O4)2(H2O)2]·4H2O