Forskning ved Københavns Universitet - Københavns Universitet


3d/4f Metal Complexes of Phenolic Oximes New Binding Sites on Anderson Polyoxometalates Metal Complexes of the New THAME Ligand

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

  • Waqas Sethi
Derivatives of phenolic oximes have been used to synthesise two large families of coordinationcomplexes namely [LnIII2MnIII4] and [LnIII2MnIII2MnIV2]. The [LnIII2MnIII4] family can be subdivided into two structural types. Complexes 1 to 9 (Type 1) can be represented by the general formula [LnIII2MnIII4O2(R-sao)4(hmp)4(O2CR’)2] (where Ln = Gd, Tb, Dy, Y; R = H, Me, Et, Ph;sao = dianion of salicylaldoxime; hmp = anion of 2-(hydroxymethyl)pyridine; R’ = CH3, C(CH3)3,Ph(CH3)2), and complexes 10 to 16 (Type 2) by the general formula [LnIII2MnIII4O2(Rsao)4(teaH)2(CH3COO)2] (where Ln = Y or Sm, Tb, Dy, Ho, Er, Lu; R = H, Me; teaH = dianion oftriethanolamine). Complexes 1-16 were characterized by SQUID (Superconducting QuantumInterference Device) magnetometry. The [LnIII2MnIII2MnIV2) family of compounds can berepresented by the general formula [LnIII2MnIII2MnIV2O2(OMe)4(Et-sao)6(MeOH)2]·xMeOH (LnIII =DyIII, ErIII, TbIII and YIII). The complexes are synthesised by mixing the appropriate metal salts andligands in basic MeOH or in a mixture of MeOH and MeCN. The metallic skeleton of [LnIII2MnIII4]and [LnIII2MnIII2MnIV2] can be viewed as made of two edge sharing [Ln2Mn2] tetrahedra or,alternatevily, of a [Ln2Mn4] distorted octahedron.
Further derivatization of phenolic oximes with ethanolamine arms results into the ligand (Z)-1-(3-((bis(2-hydroxyethyl)amino)methyl)-2-hydroxy-5-methylphenyl)ethan-1-one oxime (H4L1).Combining H4L with Zn(NO3)2·6H2O and lanthanide(III) nitrates [Gd, Dy, Sm, Eu, and Tb] in thepresence of NEt3 and tBuONa in MeOH, results into a family of complexes. This family ofcomplexes can be represented by the general formula [LnIII6ZnII2(CO3)5(OH)(H2L)4(H3L)2(H4L)]NO3·xMeOH [Ln = Gd, x = 30, for 1; Ln = Dy, x = 32, for 2; Ln = Sm, x = 31,for 3; Ln = Eu, x = 29, for 4; Ln = Tb, x = 30, for 5. Complexes 1-5 were characterized usingSQUID magnetometry. 
Next, H4L1 and the closely related (Z)-1-(3-((bis(2-hydroxyethyl)amino)methyl)-2-hydroxy-5-methylphenyl)propan-1-one oxime (H4L2) were used to synthesise four {NiII}4 complexes with adefective double-cubane structure. The magnetic cores of these complexes are made of a [Ni4O4](1-3) or a [Ni4N2O2] (4) unit. The important structural difference between structures 1-3 and 4 is that two alkoxide bridges have been replaced by two μ-N3 bridges. Direct current (dc) magnetic susceptibility studies were performed on complexes 1-4.
Three novel functionalized Anderson-type POMs were synthesized and characterized namely [TBA]3[MnMo6O18{(OCH2)3CH2Br}2] (1), [TBA]3[MnMo6O18{(OCH2)3CN=C(C6H4-4-SCH3)}2] (3) and [TBA]3[MnMo6O18{(OCH2)3CN=C(C6H4-4-CO2H)}2] (4). The magnetic properties of 4 were investigated. Both new and already known functionalised POMs were tried to be coordinatedto SMMs as well as onto other transition metal complexes, via different synthetic strategies. These synthetic routes did not result in the crystallisation of any new compounds.
A new hexadentate ligand tris(((2-hydroxyethyl)-amino)methyl)ethane (THAME) was synthesised and characterised. THAME was subsequently used to synthesise new third row transition metaldimeric compounds namely [Cr2(CH3C(CH2NHC2H4O)3)2H3](NO3)3 (1),[Mn2(CH3C(CH2NHC2H4O)3)2H3](PF6)3 (2) and [Co2(CH3C(CH2NHC2H4O)3)2H3](NO3)3 (3). Thesenovel dimeric complexes are held together by (OHO)3 bridges. The temperature dependence ofthe χMT products of polycrystalline samples of 1 and 2 with B = 0.1 T was investigated
ForlagDepartment of Chemistry, Faculty of Science, University of Copenhagen
Antal sider153
StatusUdgivet - 2015

ID: 142592532