The Coordination Chemistry of Some Sulphur-Nitrogen Ligands

<p>Some nickel(II) and copper(II) complexes of 2-(benzylthio)ethylamine have been isolated and characterised with respect to infrared and electronic spectra. With nickel(II) only the bis salts were obtained and they were all paramagnetic. An investigation of the nickel(II) and copper(II) complexes of three tetradentate ligands, each containing two sulphur and two nitrogen donor atoms, has been made. One of these, 1,9-diamino 3,7-dithianonane has been compared to the nitrogen analogue, 1,9-diamino 3,7-diazanonane. Attempts to bridge and cyclise complexes using reactions of acetone with coordinated amino groups and halides with coordinated thiol groups are also reported. Finally a novel S-detritylation reaction is discussed.</p>

The Coordination Chemistry of Some Sulphur-Nitrogen Ligands

<p>Some nickel(II) and copper(II) complexes of 2-(benzylthio)ethylamine have been isolated and characterised with respect to infrared and electronic spectra. With nickel(II) only the bis salts were obtained and they were all paramagnetic. An investigation of the nickel(II) and copper(II) complexes of three tetradentate ligands, each containing two sulphur and two nitrogen donor atoms, has been made. One of these, 1,9-diamino 3,7-dithianonane has been compared to the nitrogen analogue, 1,9-diamino 3,7-diazanonane. Attempts to bridge and cyclise complexes using reactions of acetone with coordinated amino groups and halides with coordinated thiol groups are also reported. Finally a novel S-detritylation reaction is discussed.</p>

Synthesis and Coordination of Bicyclic Phosphorus-Nitrogen Ligands

<p>This thesis describes the synthesis and coordination chemistry of bicyclic phosphorus-nitrogen (PN) ligands containing the rigid and preorganised bicyclo[3.3.1]nonan-9-one framework. The PN ligands were prepared via the Mannich condensation reaction of four different phosphorinanone classes with amines and aldehydes. The phosphorinanone compounds, 2,6-dimethyl-3,5-diphenyl-4-phenyl-4- phosphacyclohexanone (isomers 50 and 51), 3,5-diphenyl-4-phenyl-4- phosphacyclohexanone (44, 45) and 4-phenyl-4-phosphacyclohexanone (42) were prepared by literature methods, whereas the isomers of 4-t-butyl-2,6- di(carbomethoxy) - 3,5 - bis(p - dimethylaminophenyl) - 4 - phosphacyclohexanone (53, 54) were synthesised by the reaction of ButPH2 with 2,4-di(carbomethoxy)- 1,5 - bis(p - dimethylaminophenyl)penta - 1,4 - dien - 3 - one (38). The Mannich reactions of phosphorinanones 50 and 51 were not successful, whereas the reactions of 44, 45 and 42 produced unidentifiable products. The reaction of phosphorinanone 53 with methylamine and formaldehyde produced the bicyclic PN compound 7-t-butyl-1,5-di(carbomethoxy)-6,8-bis(p-dimethylaminophenyl)- 3 - methyl - 3 - aza - 7 - phosphabicyclo[3.3.1]nonan - 9 - one (65). The identical Mannich reaction of phosphorinanone 54 also yielded 65, as well as the PN compound 4-t-butyl-6-carbomethoxy-5-(p-dimethylaminophenyl)- 2-methyl-2-aza-4-phosphacyclohexanone (66) and the E/Z isomers of 3-(p-dimethylaminophenyl)methyl-2-propenoate (67). The bicyclic PN ligand 65 adopts a chair-chair conformation in solution and the solid state as confirmed by X-ray crystallography. The coordination chemistry of this ligand was comprehensively explored with rhodium, palladium and platinum, and a wide range of complexes were synthesised including [ML2(65)] (M = Pd, Pt; L = Cl, Me), [ML(65)] (M = Rh, Pd, Pt; L = C2H4, cod, dba, norb) (cod = cycloocta-1,5-diene, dba = trans,trans- dibenzylideneacetone, norb = norborn-2-ene), [Pd(n3 -C3H5)(65)]X (X = Cl, SbF6) and [PtL(65)]CH(SO2CF3)2 (L = 1-o,4-5-n-C8H13, 1-3-n-C8H13). Cycloplatination at the ortho-position of the 6,8-dimethylaminophenyl sub- stituents was an interesting feature of the coordination chemistry of PN ligand 65. Ortho-metallation at both dimethylaminophenyl groups led to the formation of complex [Pt(C2H4)(65-2H)] (76), whereas metallation of only one aryl group produced the complex [Pt(C8H13)(65-H)] (87). Further reaction of complex 76 yielded the trans- and cis-hydroxo-bridged dimers [Pt2(u-OH)2(65-H)2] (98, 101). The nitrogen donor atom is not coordinated to the platinum metal centres in the cyclometallated PN complexes. Protonation of [Pt(C2H4)(65)] (75) with CH2(SO2CF3)2 produced the hydride complex [PtH{CH(SO2CF3)2}(65)] (92) and the agostic ethyl complex [Pt(C2H5)(65)]CH(SO2CF3)2 (93). Similarly, protonation of [Pt(norb)(65)] (74) with CHPh(SO2CF3)2 gave the norbornyl agostic complex [Pt(C7H11)(65)]CPh(SO2CF3)2 (94) as confirmed by X-ray crystallography. In addition, hydrated analogues of some of the coordination complexes of PN ligand 65 mentioned previously were also observed. In such complexes, the central carbonyl group at position 9 was hydrated to form a geminal diol. The hydrated complexes exhibited similar chemical characteristics to their ketone counterparts. The 15N NMR chemical shifts of the nitrogen donor atom in PN ligand 65 and its various metal complexes were obtained from inversely-detected 1H- 15N HMBC experiments. The NMR data showed no explicit relationship between the coordination mode of the nitrogen group and the 15N chemical shift.</p>

Synthesis and Coordination of Bicyclic Phosphorus-Nitrogen Ligands

<p>This thesis describes the synthesis and coordination chemistry of bicyclic phosphorus-nitrogen (PN) ligands containing the rigid and preorganised bicyclo[3.3.1]nonan-9-one framework. The PN ligands were prepared via the Mannich condensation reaction of four different phosphorinanone classes with amines and aldehydes. The phosphorinanone compounds, 2,6-dimethyl-3,5-diphenyl-4-phenyl-4- phosphacyclohexanone (isomers 50 and 51), 3,5-diphenyl-4-phenyl-4- phosphacyclohexanone (44, 45) and 4-phenyl-4-phosphacyclohexanone (42) were prepared by literature methods, whereas the isomers of 4-t-butyl-2,6- di(carbomethoxy) - 3,5 - bis(p - dimethylaminophenyl) - 4 - phosphacyclohexanone (53, 54) were synthesised by the reaction of ButPH2 with 2,4-di(carbomethoxy)- 1,5 - bis(p - dimethylaminophenyl)penta - 1,4 - dien - 3 - one (38). The Mannich reactions of phosphorinanones 50 and 51 were not successful, whereas the reactions of 44, 45 and 42 produced unidentifiable products. The reaction of phosphorinanone 53 with methylamine and formaldehyde produced the bicyclic PN compound 7-t-butyl-1,5-di(carbomethoxy)-6,8-bis(p-dimethylaminophenyl)- 3 - methyl - 3 - aza - 7 - phosphabicyclo[3.3.1]nonan - 9 - one (65). The identical Mannich reaction of phosphorinanone 54 also yielded 65, as well as the PN compound 4-t-butyl-6-carbomethoxy-5-(p-dimethylaminophenyl)- 2-methyl-2-aza-4-phosphacyclohexanone (66) and the E/Z isomers of 3-(p-dimethylaminophenyl)methyl-2-propenoate (67). The bicyclic PN ligand 65 adopts a chair-chair conformation in solution and the solid state as confirmed by X-ray crystallography. The coordination chemistry of this ligand was comprehensively explored with rhodium, palladium and platinum, and a wide range of complexes were synthesised including [ML2(65)] (M = Pd, Pt; L = Cl, Me), [ML(65)] (M = Rh, Pd, Pt; L = C2H4, cod, dba, norb) (cod = cycloocta-1,5-diene, dba = trans,trans- dibenzylideneacetone, norb = norborn-2-ene), [Pd(n3 -C3H5)(65)]X (X = Cl, SbF6) and [PtL(65)]CH(SO2CF3)2 (L = 1-o,4-5-n-C8H13, 1-3-n-C8H13). Cycloplatination at the ortho-position of the 6,8-dimethylaminophenyl sub- stituents was an interesting feature of the coordination chemistry of PN ligand 65. Ortho-metallation at both dimethylaminophenyl groups led to the formation of complex [Pt(C2H4)(65-2H)] (76), whereas metallation of only one aryl group produced the complex [Pt(C8H13)(65-H)] (87). Further reaction of complex 76 yielded the trans- and cis-hydroxo-bridged dimers [Pt2(u-OH)2(65-H)2] (98, 101). The nitrogen donor atom is not coordinated to the platinum metal centres in the cyclometallated PN complexes. Protonation of [Pt(C2H4)(65)] (75) with CH2(SO2CF3)2 produced the hydride complex [PtH{CH(SO2CF3)2}(65)] (92) and the agostic ethyl complex [Pt(C2H5)(65)]CH(SO2CF3)2 (93). Similarly, protonation of [Pt(norb)(65)] (74) with CHPh(SO2CF3)2 gave the norbornyl agostic complex [Pt(C7H11)(65)]CPh(SO2CF3)2 (94) as confirmed by X-ray crystallography. In addition, hydrated analogues of some of the coordination complexes of PN ligand 65 mentioned previously were also observed. In such complexes, the central carbonyl group at position 9 was hydrated to form a geminal diol. The hydrated complexes exhibited similar chemical characteristics to their ketone counterparts. The 15N NMR chemical shifts of the nitrogen donor atom in PN ligand 65 and its various metal complexes were obtained from inversely-detected 1H- 15N HMBC experiments. The NMR data showed no explicit relationship between the coordination mode of the nitrogen group and the 15N chemical shift.</p>

Investigation of Substitution Reactions Between Zinc(II) Complexes with Different Geometries and N-bonding Nucleophiles

Aims: Investigation of interactions between zinc(II) complexes with different geometrical structures and relevant nitrogen donor nucleophiles at physiological pH. Background: The lack of clear distinction between the therapeutic and toxic doses of platinum drugs is a major challenge for the design of novel non-platinum DNA and protein targeting metal-based anticancer agents. The non-platinum antitumor complexes could be alternatives to platinum-based drugs due to their better characteristics and different mechanism of action. Objective This study could provide more information for the design of future zinc-based anticancer drugs, as well as providing a better understanding of the mechanism of interactions between Zn(II) complexes and nitrogen-donor nucleophiles (important from a medical point of view) and clarifies the changes in geometrical structures of zinc(II) that are referred to structure-reactivity correlation Methods Mole-ratio method and UV-Vis spectroscopic kinetic method were applied in this study. Objective : This study could provide more information for the design of future zinc-based anticancer drugs, as well as providing a better understanding of the mechanism of interactions between Zn(II) complexes and nitrogen-donor nucleophiles (important from a medical point of view) and clarifies the changes in geometrical structures of zinc(II) that are referred to structure-reactivity correlation Methods Mole-ratio method and UV-Vis spectroscopic kinetic method were applied in this study. Result: The results indicated additional coordination of chlorides in the first coordination sphere with changes in coordination geometry and formation of the octahedral complex anion [ZnCl4(en)]2- while an excess of chloride didn’t affect the square-pyramidal structure of [ZnCl2(terpy)]. The substitutions of studied complexes and relevant nucleophiles proceed in two consecutive reaction steps that depend on the nucleophile concentration. Octahedral complex anion [ZnCl4(en)]2- forms rapidly, and all substitution processes of this complex species should be considered. We assume that the first reaction step is accompanied by the dissociation of chloride ligands. Nucleophile 1,2,4-triazole have shown the highest affinity toward [ZnCl2(en)], and rates of both steps are almost the same value, which indicates parallel reactions. Conclusion: The different order of reactivity of relevant N-donor ligands toward [ZnCl2(en)] and [ZnCl2(terpy)] complexes for the first reaction step occurred due to the influence of different geometrical structures of complexes. In contrast, low reaction rates for the second reactions of [ZnCl2(en)] complex with imidazole and pyrazine were a consequence of interconversion between octahedral and tetrahedral structure during substitution processes.