Mononuclear molybdenum(VI) complexes with hydrazone ligands: trans-influence of oxygen atom

Abstract

U okviru ovog diplomskog rada ispitivane su reakcije salicilaldehid benzoilhidrazona, 4– metoksisalicilaldehid benzoilhidrazona i 3–metoksisalicilaldehid benzoilhidrazona s bis(pentan–2,4– dionato)dioksomolibdenom(VI). Kompleksi su priređeni klasičnim metodama sinteze (na sobnoj i na povišenoj temperaturi te solvotermalno). Izolirani produkti mogu se opisati formulom [MoO2(L)(D)], gdje je L tridentatni, dvostruko deprotonirani hidrazonato ligand, a D neutralna molekula otapala (metanol, voda, piridin) vezana kao monodentatni ligand na šesto koordinacijsko mjesto. Kako bi se dodatno istražila jakost veze između neutralnog monodentatnog liganda i metalnog centra, kompleksi su otopljeni u etanolu, n–propanolu, n–butanolu, t–butanolu, piridinu, α–pikolinu i γ−pikolinu. Kompleksi su također izlagani parama otapala, pri čemu dolazi do zamjene neutralnog liganda molekulom otapala. Dodatno, otapanjem [MoO2(VanHB)(MeOH)] (VanHB = salicilaldehid 3– metoksibenzoilhidrazon) u acetonitrilu, priređen je polimerni kompleksni spoj koji se može opisati formulom [MoO2(VanHB)]n ∙ nCH3CN. Svi dobiveni produkti su okarakterizirani na temelju podataka iz infracrvenih spektara i difrakcije rendgenskog zračenja na polikristalnom uzorku, a u pojedinim slučajevima i termogravimetrijske analize, kao i difrakcije rentgenskog zračenja na jediničnom kristalu. Izolirani kompleksi kojima je određena molekulska i kristalna struktura su: [MoO2(L)(MeOH)], [MoO2(L)(OH2)] (L= salicilaldehid benzoilhidrazon, salicilaldehid 4–metoksibenzoilhidrazon ili salicilaldehid 3–metoksibezoilhidrazon), [MoO2(L2)py] (L2 = salicilaldehid 4–metoksibenzoilhidrazon) i [MoO2(L3)]n · nCH3CN (L3 = salicilaldehid 3–metoksibezoilhidrazon).In this diploma thesis reactions of salicylaldehyde benzoylhydrazone, salicylaldehyde 4– metoxybenzoylhydrazone and salicylaldehyde 3–metoxybezoylhydrazone with bis[penatane–2, 4–dionato]dioxomolybdenum(VI), [MoO2(acac)2] were investigated. Complexes were synthesised by means of conventional chemical synthesis using methanole or acetonitrile as solvent (at room temperature, under reflux and under solvotermal conditions). Products of reactions were complexes with general formula [MoO2(L)(D)], L = tridentate, double deprotonated hydrazone ligand, D = neutral solvent molecule (methanole, water or pyridine) coordinated to molybdenum ion. In order to further investigate the strenght of the bond between metal center and neutral ligand D, trans to oxygen atom of cis–MoO2 2+, prepared complexes were dissolved or exposed to vapors of ROH (R = –C2H5, –C3H7, – C4H9) and N–bases (pyridine, α–picoline and γ–picoline). The results were new complexes in which ligand D, coordinated to molybdenum was exchanged. All isolated products were characterised by means of infrared spectroscopy and PXRD, in some cases by means of thermogravimetric analisys and when it was possible by X–ray diffraction on single crystals. Following complexes were isolated and their molecular and crystal structures were determined: [MoO2(L)(MeOH)], [MoO2(L)(OH2)] (L= salicylaldehyde benzoylhydrazone, salicylaldehyde 4–metoxybenzoylhydrazone or salicylaldehyde 3–metoxybezoylhydrazone), [MoO2(L2)py] (L2 = salicylaldehyde 4–metoxybenzoylhydrazone) and [MoO2(L3)]n · nCH3CN (L3 = salicylaldehyde 3–metoxybezoylhydrazone)