Rhenium complexes with pontentially multidentate ligands containing the amino, imino, hydroxy and thiol groups
- Authors: Mukiza, Janvier
- Date: 2016
- Subjects: Rhenium Thiols Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12308 , vital:27053
- Description: The chemistry of rhenium has received considerable interest due to its versatility in various catalytic applications, fixation and especially the potential use of 186Re and 188Re radionuclides in nuclear medicine. This study investigates the synthesis and characterisation of rhenium complexes with potentially multidentate ligands containing the amino, imino, hydroxyl and thiol groups. It reports new rhenium complexes in the +1, +3, +4 and +5 oxidation states, which display structural diversity, from monomers to ligand-bridged dimers as well as metal-metal multiply bonded dimers. The reaction of orotic acid (H2oa) and 2-mercapto-orotic acid (H2moa) with trans- [ReOX3(PPh3)2] (X = Cl, Br) were studied and led to the formation of ligand-bridged dimers with metal-metal multiple bonds i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-X)(μ-O)(μ-oa)[Re2 IVX2(OiPr)(PPh3)2] and (μ-Cl)(μ-O)(μ-moa)2[Re(PPh3)]2. The reaction of H2oa with [ReO2(py)4]Cl, [Re(dab)Br3(PPh3)2] (H2dab = 1,2- diaminobenzene) and [Re(CO)5Cl] were also studied and monomeric complexes [ReO(py)2(OEt)(oa)], [Re(dab)Br(oa)(PPh3)2] and (Ph4P)[Re(CO)3(H2O)(oa)] were isolated. The treatment of 5-amino-orotic acid (H2aoa) with [ReOBr3(PPh3)2] led to dimers with metal-metal triple bonds ReIV≡ReIV i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-Br)(μ-O)(μ-oa)[Re2 IVBr2(OiPr)(PPh3)2], as well as the monomer [ReV(apd)Br(aoa)(PPh3)2] (apd2− = 5-imidopyrimidine-2,4-dione). The chelating ligand 5-aminopyrimidine-2,4-dione (H2apd) was formed by oxorhenium(V)-catalysed decarboxylation of 5-amino-orotic acid (H2aoa) (see Scheme 1). The reaction of the Schiff base derivative of 5-amino-ortic acid, salicylimine-orotic acid (H2soa), with trans-[ReOI2(OEt)(PPh3)2] in ethanol was also investigated and led to the formation of the rhenium(III) complex salt [Re(coa)I(PPh3)2]I [Hcoa = 5-(2- hydroxybenzylideneamino)pyrimidine-2,4(1H,3H)-dione]. The chelating Hcoa is also formed from the oxorhenium(V)-catalysed decarboxylation of H2soa and coordinates to the rhenium(III) ion as a monoanionic tridentate N,O,O-donor chelate via the phenolate and ketonic oxygens, and the imino nitrogen atom. However, decarboxylation of H2soa was not observed in its reaction with [ReOCl3(PPh3)2], which led to the isolation of [ReOCl(soa)(PPh3)]. The reaction of the carboxamide derivative of 5-aminoorotic acid, 5-(5-aminopyrimidine-2,4(1H,3H)- dioxamido)-1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-carboxylic acid (H2ampa) with [Re(CO)5Cl] in ethanol led to the formation of a zwitterionic rhenium(I) complex [Re(CO)3(H2O)(amef)] [amef = {5-(5-ammoniumpyrimidine-2,4(1H,3H)-dioxamido)- 1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-ethylformate}]. The chelating ion amef was formed from the combined tricarbonylrhenium(I)-catalysed esterification and aminoprotonation of H2ampa (see Scheme 1) and coordinates to the fac-[Re(CO)3]+ core as a dianionic bidentate N,N-donor chelate via the amido nitrgens.
- Full Text:
- Date Issued: 2016
- Authors: Mukiza, Janvier
- Date: 2016
- Subjects: Rhenium Thiols Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12308 , vital:27053
- Description: The chemistry of rhenium has received considerable interest due to its versatility in various catalytic applications, fixation and especially the potential use of 186Re and 188Re radionuclides in nuclear medicine. This study investigates the synthesis and characterisation of rhenium complexes with potentially multidentate ligands containing the amino, imino, hydroxyl and thiol groups. It reports new rhenium complexes in the +1, +3, +4 and +5 oxidation states, which display structural diversity, from monomers to ligand-bridged dimers as well as metal-metal multiply bonded dimers. The reaction of orotic acid (H2oa) and 2-mercapto-orotic acid (H2moa) with trans- [ReOX3(PPh3)2] (X = Cl, Br) were studied and led to the formation of ligand-bridged dimers with metal-metal multiple bonds i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-X)(μ-O)(μ-oa)[Re2 IVX2(OiPr)(PPh3)2] and (μ-Cl)(μ-O)(μ-moa)2[Re(PPh3)]2. The reaction of H2oa with [ReO2(py)4]Cl, [Re(dab)Br3(PPh3)2] (H2dab = 1,2- diaminobenzene) and [Re(CO)5Cl] were also studied and monomeric complexes [ReO(py)2(OEt)(oa)], [Re(dab)Br(oa)(PPh3)2] and (Ph4P)[Re(CO)3(H2O)(oa)] were isolated. The treatment of 5-amino-orotic acid (H2aoa) with [ReOBr3(PPh3)2] led to dimers with metal-metal triple bonds ReIV≡ReIV i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-Br)(μ-O)(μ-oa)[Re2 IVBr2(OiPr)(PPh3)2], as well as the monomer [ReV(apd)Br(aoa)(PPh3)2] (apd2− = 5-imidopyrimidine-2,4-dione). The chelating ligand 5-aminopyrimidine-2,4-dione (H2apd) was formed by oxorhenium(V)-catalysed decarboxylation of 5-amino-orotic acid (H2aoa) (see Scheme 1). The reaction of the Schiff base derivative of 5-amino-ortic acid, salicylimine-orotic acid (H2soa), with trans-[ReOI2(OEt)(PPh3)2] in ethanol was also investigated and led to the formation of the rhenium(III) complex salt [Re(coa)I(PPh3)2]I [Hcoa = 5-(2- hydroxybenzylideneamino)pyrimidine-2,4(1H,3H)-dione]. The chelating Hcoa is also formed from the oxorhenium(V)-catalysed decarboxylation of H2soa and coordinates to the rhenium(III) ion as a monoanionic tridentate N,O,O-donor chelate via the phenolate and ketonic oxygens, and the imino nitrogen atom. However, decarboxylation of H2soa was not observed in its reaction with [ReOCl3(PPh3)2], which led to the isolation of [ReOCl(soa)(PPh3)]. The reaction of the carboxamide derivative of 5-aminoorotic acid, 5-(5-aminopyrimidine-2,4(1H,3H)- dioxamido)-1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-carboxylic acid (H2ampa) with [Re(CO)5Cl] in ethanol led to the formation of a zwitterionic rhenium(I) complex [Re(CO)3(H2O)(amef)] [amef = {5-(5-ammoniumpyrimidine-2,4(1H,3H)-dioxamido)- 1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-ethylformate}]. The chelating ion amef was formed from the combined tricarbonylrhenium(I)-catalysed esterification and aminoprotonation of H2ampa (see Scheme 1) and coordinates to the fac-[Re(CO)3]+ core as a dianionic bidentate N,N-donor chelate via the amido nitrgens.
- Full Text:
- Date Issued: 2016
Synthesis and characterisation of oxorhenium(V) and tricarbonylrhenium(I) complexes with biologically active N, O and N, S-Donor ligands
- Authors: Mukiza, Janvier
- Date: 2013
- Subjects: Rhenium , Rhenium compounds , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10437 , http://hdl.handle.net/10948/d1020769
- Description: This study investigated the synthesis of rhenium(I) and rhenium(V) complexes with a variety of multidentate NS, NSO, NO and SO-donor ligands. It also investigated the synthesis of dinuclear dihalogeno- and trihalogeno-bridged rhenium(I) complexes based on the fac-[Re(CO)3]+ core. The reactions of hydrated folic acid with [Re(CO)5X] (X = Cl, Br) were studied, and the complexes [Re(CO)3(H2O)3]+[Re2(μ-X)3CO)6]−.5H2O [X= Br (1), Cl(2)] were isolated. The reaction of orotic acid potassium salt [Re(CO)5Br] was performed, and the complex [Re2(μ-Br)2(CO)8] was isolated. The reaction of bis(piperidin-1- yl)methanone with [Re(CO)5Cl] followed by recrystallisation of the resulting precipitate in dichloromethane/acetontrile resulted in the complex [Re2(μ- Cl)2(CO)6(MeCN)2]. The X-ray crystal structures show that all these complexes display a distorted octahedral geometry around the central rhenium atoms. The reactions of aroylhydrazone-based ligands such as 3-((pyridin- 2yl)methyleneamino)-2,3-dihydro-2-pyridin-2yl)quinazolin-4-(1H)-one (Hppq) and N-(di(pyridin-2-yl)methylene)benzohydrazide (Hdpmb) with [Re(CO)5Cl] were studied and led to the formation of the complexes [Re(CO)3Cl(Hdpmb)] and [Re(CO)3Cl(Hppq)]. The Hdpmb and Hppq coordinated to the fac-[Re(CO)3]+ core as neutral bidentate chalates via the pyridinic nitrogens (for Hdpmb) and via imino and pyridinic nitrogens for Hppq. The X-ray crystal structures show that the geometry around the rhenium in both complexes is a distorted octahedral. The treatment of the dithizone (H2dz) ligand with rhenium(V) precursors containing a triphenylphosphine group (PPh3) led to the decomposition of dithizone. The decomposition product reacted with the triphenylphosphine group and generated a new ligand triphenylphosphazeno-N-phenylmethanethiohydrazide (H2L). The reaction of trans-[ReOX3(PPh3)2] (X = Cl, Br) with dithizone (H2dz) led to the complex [ReO(dz)2][ReO(HL)2]. The reaction of trans-[ReOI2(OEt)(PPh3)2] with H2dz led to the same product. The reaction of cis-[ReO2I(PPh3)2] with H2dz in methanol led to [ReO(dz)2][ReO(HL)2](MeOH)2 in which methanol bonded to HLvia hydrogen bonds. The H2dz was doubly deprotonated and coordinated to the [ReO]3+ moiety via a thiolate sulfur and deprotonated hydrazinic nitrogen to yield [ReO(dz)2]−, while the H2L was singly deprotonated and coordinated to [ReO]3+ moiety via the neutral sulfur atom and deprotonated hydrazinic nitrogen to yield [ReO(HL)2]+. The X-ray crystal structure show that in both [ReO(HL)2]+ and [ReO(dz)2]−, the rhenium atoms are five-coordinated and adopt a distorted squarebased pyramidal geometry. The reaction of thiosemicarbazones such as salcylidene-4- phenylthiosemicarbazide (H3salpt) with cis-[ReO2I(PPh3)2] was investigated and led to the complex [ReO(Hsalpt)(H2salpt)]. The X-ray study reveals that Hsalpt is present as a tridentate chelate coordinating via the thiolate sulfur, imino nitrogen and phenolic oxygen, while H2salpt coordinates as a bidentate chelate via the thiolate sulfur and imino nitrogen atoms. The geometry around rhenium is distorted octahedral. The coordination mode of the benzoylthiourea derivatives 4-tert-butyl-N- (diphenylcarbamothioyl)benzamide (Htpb) and N-(diethylcarbamothioyl)benzamide (Heb) to the [Re2O3]4+ and fac-[Re(CO)3]+ cores were investigated. The reaction of [Re(CO)5Cl] in presence of sodium acetate with Htpb led to the dimeric complex [Re(CO)3(tpb)]2 in which the tpb coordinated to the fac-[Re(CO)3]+ core via the ketonic oxygen and bridging thiolate sulfur. The same reaction with Heb led to the monomeric complex [Re(CO)3(eb)(Heb)], in which the eb coordinates to the fac-[Re(CO)3]+core via thiolate sulfur and ketonic oxygen with Heb binding via the neutral sulfur atom. The reaction of Heb with cis-[ReO2I(PPh3)2] at room temperature with excess of sodium acetate led to the dimeric complex (μ-O)[ReO(eb)2]2 in which Heb is present as a monoanionic (deprotonated) bidentate with coordination through the thiolate sulfur and ketonic oxygen.
- Full Text:
- Date Issued: 2013
- Authors: Mukiza, Janvier
- Date: 2013
- Subjects: Rhenium , Rhenium compounds , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10437 , http://hdl.handle.net/10948/d1020769
- Description: This study investigated the synthesis of rhenium(I) and rhenium(V) complexes with a variety of multidentate NS, NSO, NO and SO-donor ligands. It also investigated the synthesis of dinuclear dihalogeno- and trihalogeno-bridged rhenium(I) complexes based on the fac-[Re(CO)3]+ core. The reactions of hydrated folic acid with [Re(CO)5X] (X = Cl, Br) were studied, and the complexes [Re(CO)3(H2O)3]+[Re2(μ-X)3CO)6]−.5H2O [X= Br (1), Cl(2)] were isolated. The reaction of orotic acid potassium salt [Re(CO)5Br] was performed, and the complex [Re2(μ-Br)2(CO)8] was isolated. The reaction of bis(piperidin-1- yl)methanone with [Re(CO)5Cl] followed by recrystallisation of the resulting precipitate in dichloromethane/acetontrile resulted in the complex [Re2(μ- Cl)2(CO)6(MeCN)2]. The X-ray crystal structures show that all these complexes display a distorted octahedral geometry around the central rhenium atoms. The reactions of aroylhydrazone-based ligands such as 3-((pyridin- 2yl)methyleneamino)-2,3-dihydro-2-pyridin-2yl)quinazolin-4-(1H)-one (Hppq) and N-(di(pyridin-2-yl)methylene)benzohydrazide (Hdpmb) with [Re(CO)5Cl] were studied and led to the formation of the complexes [Re(CO)3Cl(Hdpmb)] and [Re(CO)3Cl(Hppq)]. The Hdpmb and Hppq coordinated to the fac-[Re(CO)3]+ core as neutral bidentate chalates via the pyridinic nitrogens (for Hdpmb) and via imino and pyridinic nitrogens for Hppq. The X-ray crystal structures show that the geometry around the rhenium in both complexes is a distorted octahedral. The treatment of the dithizone (H2dz) ligand with rhenium(V) precursors containing a triphenylphosphine group (PPh3) led to the decomposition of dithizone. The decomposition product reacted with the triphenylphosphine group and generated a new ligand triphenylphosphazeno-N-phenylmethanethiohydrazide (H2L). The reaction of trans-[ReOX3(PPh3)2] (X = Cl, Br) with dithizone (H2dz) led to the complex [ReO(dz)2][ReO(HL)2]. The reaction of trans-[ReOI2(OEt)(PPh3)2] with H2dz led to the same product. The reaction of cis-[ReO2I(PPh3)2] with H2dz in methanol led to [ReO(dz)2][ReO(HL)2](MeOH)2 in which methanol bonded to HLvia hydrogen bonds. The H2dz was doubly deprotonated and coordinated to the [ReO]3+ moiety via a thiolate sulfur and deprotonated hydrazinic nitrogen to yield [ReO(dz)2]−, while the H2L was singly deprotonated and coordinated to [ReO]3+ moiety via the neutral sulfur atom and deprotonated hydrazinic nitrogen to yield [ReO(HL)2]+. The X-ray crystal structure show that in both [ReO(HL)2]+ and [ReO(dz)2]−, the rhenium atoms are five-coordinated and adopt a distorted squarebased pyramidal geometry. The reaction of thiosemicarbazones such as salcylidene-4- phenylthiosemicarbazide (H3salpt) with cis-[ReO2I(PPh3)2] was investigated and led to the complex [ReO(Hsalpt)(H2salpt)]. The X-ray study reveals that Hsalpt is present as a tridentate chelate coordinating via the thiolate sulfur, imino nitrogen and phenolic oxygen, while H2salpt coordinates as a bidentate chelate via the thiolate sulfur and imino nitrogen atoms. The geometry around rhenium is distorted octahedral. The coordination mode of the benzoylthiourea derivatives 4-tert-butyl-N- (diphenylcarbamothioyl)benzamide (Htpb) and N-(diethylcarbamothioyl)benzamide (Heb) to the [Re2O3]4+ and fac-[Re(CO)3]+ cores were investigated. The reaction of [Re(CO)5Cl] in presence of sodium acetate with Htpb led to the dimeric complex [Re(CO)3(tpb)]2 in which the tpb coordinated to the fac-[Re(CO)3]+ core via the ketonic oxygen and bridging thiolate sulfur. The same reaction with Heb led to the monomeric complex [Re(CO)3(eb)(Heb)], in which the eb coordinates to the fac-[Re(CO)3]+core via thiolate sulfur and ketonic oxygen with Heb binding via the neutral sulfur atom. The reaction of Heb with cis-[ReO2I(PPh3)2] at room temperature with excess of sodium acetate led to the dimeric complex (μ-O)[ReO(eb)2]2 in which Heb is present as a monoanionic (deprotonated) bidentate with coordination through the thiolate sulfur and ketonic oxygen.
- Full Text:
- Date Issued: 2013
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