Molybdenum(VI) complexes with asymmetric carbohydrazides

Abstract

U okviru ovog rada pripravljena su dva monosupstituirana karbonohidrazida, 1-(2- hidroksibenziliden)karbonohidrazid, H3Lsal te 1-(piridin-3-ilmetiliden)karbonohidrazid metanol solvat, H2Lpy·MeOH. Korištenjem tih spojeva kao prekursora pripravljena su dva asimetrično disupstituirana karbonohidrazida, 1-(2-hidroksi-3-metoksibenziliden)-5-(2-hidroksibenziliden)karbonohidrazid, H4Lovansal, i 1-(2-hidroksibenziliden)-5-(piridin-3-ilmetiliden)karbonohidrazid, H3Lpy-sal. Pripravljeni asimetrično disupstituirani derivati H4Lovan-sal i H3Lpy-sal u reakcijama s dioksobis(pentan-2,4- dionato)molibdenom(VI), [MoO2(acac)2], dali su odgovarajuće kompleksne spojeve molibdena(VI). Reakcijom H4Lovan-sal s [MoO2(acac)2] u metanolu ili etanolu nastaju dinuklearni kompleksni spojevi tipa [(MoO2)2Lovan-sal(ROH)2], gdje je Lovan-sal deprotonirani oblik heksadenatnog liganda, dok ROH označava MeOH ili EtOH. U svim slučajevima radi se o kompleksima u kojima se oba atoma molibdena nalaze u oktaedarskom okruženju. U slučaju spoja [(MoO2)2(Lovan-sal)(EtOH)2] izolirana su dva solvata spoja, [(MoO2)2(Lovan-sal)(EtOH)2]·EtOH i [(MoO2)2(Lovan-sal)(EtOH)2] · 2 EtOH. Reakcija H4Lovan-sal i [MoO2(acac)2] u acetonitrilu rezultirala je polimernim produktom opće formule [(MoO2)2Lovan-sal]n. Izlaganjem istog parama metanola nastaje kompleksni spoj [(MoO2)2(Lovansal)( MeOH)2], dok u slučaju etanola nije moguće tim postupkom prirediti analogni spoj. Reakcijom dioksobis(pentan-2,4-dionato)molibdena(VI) s H3Lpy-sal u metanolu priređen je mononuklearni kompleks, [MoO2(HLpy-sal)(MeOH)], gdje je HLpy-sal dianionski oblik liganda H3Lpy-sal. Provođenje analogne sinteze u acetonitrilu rezultira nastankom višenuklearnog spoja [(MoO2)(HLpysal)] ·0,61CH3CN]n. Zagrijavanjem spoja moguće je ukloniti acetonitril, prisutan u kristalnoj rešetki, pri čemu zaostaje [MoO2(HLpy-sal)]n. Izlaganjem [MoO2(HLpy-sal)]n parama metanola nastaje [MoO2(HLpysal)( MeOH)]. Svi spojevi su identificirani i okarakterizirani na temelju podataka infracrvene spektroskopije, difrakcije rentgentskog zračenja na praškastom uzorku, metodama termičke analize, te u slučajevima kada je to bilo moguće difrakcijom rentgenskog zračenja na jediničnom kristalu.Two monosubstituted carbohydrazides, 1-(2-hydroxybenzylidene)carbohydrazide, H3Lsal, and 1-(pyridine-3-ylmethylidene)carbohydrazide methanol solvate, H2Lpy·MeOH, were prepared. Using such monosubstituted carbohydrazides as pecursors two new asymmetric disubstituted derivatives were obtained, 1-(2-hydroxy-3-methoxybenzylidene)-5-(2-hydroxybenzylidene)carbohydrazide, H4Lovan-sal, and 1- (2-hydroxybenzylidene)-5-(pyridin-3-methylidene)carbohydrazids, H3Lpy-sal. Disubstituted carbohydrazides H4Lovan-sal and H3Lpy-sal in the reactions with dioxobis(pentane-2,4- dionato)molybdenum(VI), [MoO2(acac)2], yielded dinuclear or polynuclear Mo(VI) complexes. Reactions of H4Lovan-sal and [MoO2(acac)2] in methanol or ethanol gave dinuclear molybdenum(VI) complexes of the type [(MoO2)2Lovan-sal(ROH)2], where Lovan-sal denotes deprotonated form of the hexadenatate ligand used, while ROH stands for MeOH or EtOH. In such complexes both molybdenum atoms are found in distorted octahedral environment. For the complex [(MoO2)2(Lovansal)( EtOH)2], two of its solid forms were established, [(MoO2)2(Lovan-sal)(EtOH)2]·EtOH and [(MoO2)2(Lovan-sal)(EtOH)2] · 2 EtOH. Reaction of H4Lovan-sal and [MoO2(acac)2] in acetonitrile gave polymeric product [(MoO2)2Lovan-sal]n. By exposing this compound to methanol vapors it was possible to obtain [(MoO2)2(Lovan-sal)(MeOH)2], whereas the same was not viable in the case of ethanol. Reaction of H3Lpy-sal and [MoO2(acac)2] in methanol yielded mononuclear complex [MoO2(HLpysal)( MeOH)], where HLpy-sal stands for dianionic form of the ligand H3Lpy-sal. When the reaction was conducted in acetonitrile, high-nuclearity complex [(MoO2)(HLpy-sal)]·0,61CH3CN]n was obtained. Upon heating, acetonitrile molecules can be removed from the lattice, while leaving [MoO2(HLpy-sal)]n. By exposing this heating residue to methanol vapors it was possible to obtain [MoO2(HLpy-sal)(MeOH)]. All compounds were identified and characterized by means of infrared spectroscopy, X-ray powder diffraction, thermal analysis and when it was possible via single-crystal X-ray diffraction