title: An Investigation of the Multifunctional Alkylation Chemistry of [Pt₂(μ-S)₂(PPh₃)₄]

authors: Ujam, Oguejiofo Theophilus

subjects: Alkylation

abstract: This thesis presents the studies on the multifunctional alkylation of the metalloligand [Pt₂ (μ-S)₂(PPh₃)₄] 1.1. Multifunctional organic groups which include semicarbazone and thiosemicarbazone, urea, isocyanate, guanidine, ketones and amides react with 1.1 to generate the corresponding functionalised derivatives containing thiolate ligands produced by alkylation of one or both sulfide centres. Polymers with suitable electrophilic branches also react to immobilise 1.1. By using Electrospray Ionisation Mass Spectrometry (ESI-MS) as the monitoring technique, [Pt₂ (μ-S)₂(PPh₃)₄] was employed as a productive template for structurally and chemically diverse thiolate-platinum complexes. Before this study, 1.1 was known to be one of the best building blocks for multimetallic molecules through the exceptional ligating ability of the two sulfide centres to virtually any transition and main group metal fragment. However, extension of the synthetic versatility of 1.1 to multifunctional non-metallic positive centres has only been explored to a lesser extent and thus far less developed.
This thesis is organised into five chapters. Chapter one is the review of literature on [Pt₂ (μ-S)₂(PPh₃)₄] and the development of its chemistry from an efficacious metalloligand for multimetallic assembly to a powerful nucleophile for organic electrophiles. The main geometry and electronic features of 1.1 and analogous complexes were highlighted especially as it affects the dihedral angle (θ) between the two Pt₂S₂ planes in [Pt₂ (μ-S)₂(PPh₃)₄]. The variable reaction modes of 1.1 with different electrophiles were discussed especially as it may affect the less studied multifunctional alkylation. The effectiveness of the ESI-MS as a monitoring tool in the study of 1.1 chemistry is also discussed.
Chapter two details the study of the multifunctional monoalkylation reactions of the aforementioned array of multifunctional organic groups with [Pt₂ (μ-S)₂(PPh₃)₄]. Alkylation reaction of 1.1 with organo-halide of the type R–CH₂-X and R–CH₂CH₂-X (R= organic group and X = Cl or Br) formed thiolate-bridged platinum complexes. The main discovery in this study is that any suitable organic functionality can be incorporated into an electrophile for 1.1. By using the ESI-MS monitoring technique, they successfully reacted with 1.1 to give novel monoalkylated platinum complexes with μ-thiolate ligands of the type [Pt₂(μ-S){μ-SR}(PPh₃)₄](PF₆) which included [Pt₂(μ-S){μ-SCH₂C(=NNHC(O)NH₂)R} (PPh₃)₄](PF₆) in 2.1b•PF₆ (R = Ph) and 2.2b•PF₆ (R = CH₃) and [Pt₂(μ-S){μ-SR}(PPh₃)₄](PF₆) (R = -CH₂C(=NOH)Ph 2.3b•PF₆, -CH₂C(=NNHC(NH₂)NH₂) Ph 2.4b•(PF₆)₂, -CH₂C(=NNHC(S)NH₂)CH₂ 2.5b•PF₆, -CH₂CH₂NHC(O)NHPy 2.6b•PF₆ (Py = o-C₅H₄N), -CH₂CH₂NHC(O)N(CH₂CH₂)₂S 2.7b•PF₆ and -CH₂ C(O)NHC(O)NHCH₂CH₃ 2.8b•PF₆. -CH₂C(═NNHTs)Ph 2.9b•PF₆, -CH₂C(═N NHTs)CH₃ 2.10b•PF₆ (Ts = -SO₂C₆H₄CH₃), -CH₂C(=NHNC(O) Py)Ph (Py = o-C₅H₄N) 2.11b•PF₆ and -CH₂C(=NNHC(O)NH₂)C₆H₄C₆H₅ 2.12b•PF₆. Geome- trical isomers formed with BrCH₂C(NNHAr)C₆H₄Ph 2.13a (Ar = 2,4-dinitrophenyl) was studied and characterised with 2D NMR techniques. The X-ray crystal structures of 2.1b•PF₆, 2.4b•(PF₆)₂, 2.7b•PF₆ and 2.8b•PF₆ are also reported.
Chapter three reports an investigation of conditions that encourage the formation of homo- and heterodialkylated thiolate complexes of the type [Pt₂(μ-SR)₂(PPh₃)4]² + and [Pt₂(μ-SR){μ-SR'}(PPh₃)₄]²+ since these are currently not well understood. The factors were employed in the selective choice of alkylating agents used in the sequential syntheses of homodialkylated derivatives [Pt₂(μ-SCH₂COPh)₂(PPh₃)₄](PF₆)2 3.1b•(PF₆)₂, [Pt₂(μ-SCH₂C(O)pyr)₂(PPh₃)₄](PF₆)₂ (pyr = pyrene) 3.2b•(PF₆)₂ and [Pt₂(μ-SCH₂C(O)cyl)₂(PPh₃)₄](PF₆)₂ (cyl = coumaryl) (3.4b•(PF₆)₂. A major outcome of this study is the successful syntheses of the heterodialkylated derivatives [Pt₂(μ-SCH₂C(O)Ph)(μ-SBu)(PPh₃)₄](PF₆)₂ 3.5b•(PF₆)₂ and {Pt₂(μ-SCH₂COPh)(μ-SCH₂CH₃)(PPh₃)₄}(PF₆)₂ 3.6b•(PF₆)₂ through a sequential alkylation with organo-halide electrophiles. The X-ray crystal structures of 3.1b•(PF₆)₂ and 3.5b•(BPh₄)₂ are reported. The secondary products resulting from the displacement of a PPh₃ by Br- in the synthesis of the heterodialkylated derivatives 3.5b•(PF₆)₂ and 3.6b•(PF₆)₂, [Pt₂(μ-SCH₂C(O)Ph) (μ-SBu)(PPh₃)₃Br](PF₆) 3.5c•PF₆ and [Pt₂(μ-SCH₂COPh)(μ-SCH₂CH₃)(PPh₃)₃ Br](PF₆) 3.6c•PF₆ were also isolated and characterised by ESI-MS and X-ray crystallography.
Chapter four describes the multifunctional intra- and intermolecular bridging dialkylation of 1.1. The variable alkylation mode of α,ω-dialkylating electrophiles, which is dependent on the nature and the number of spacer atoms, was investigated with functionalised electrophiles, ClCH₂C(O)CH₂Cl 4.1a, ClCH₂C(NNHC(O)NH₂) CH₂Cl 4.2a and ClCH₂C(O)NHNHC(O)CH₂Cl 4.3a. A very important novel result is the stabilisation and isolation of an intramolecular bridged five-membered ring derivative 4.1b•PF₆ [Pt₂{μ-SCH₂C(O)CHS}(PPh₃)₄] (PF₆). The reaction of 4.1a with 1.1 in the presence of dilute aqueous NaOH aided the isolation of 4.1b•PF₆ resulting from intramolecular rearrangement of the four membered ring. The semicarbazone derivative 4.2a and diamide 4.3a dialkylated 1.1 by bridging the two sulfide centres to form stable [Pt₂{μ-SCH₂C(NNHC (O)NH₂)CH₂S-μ}(PPh₃)₄](BPh₄)₂ 4.2b•(BPh₄)₂ and Pt₂{μ-SCH₂C(O)NHNH(O) CH₂S}(PPh₃)₄(PF₆)₂ 4.3b•(PF₆)₂. Both 4.1b•PF₆ and 4.2b•(BPh₄)₂ were characterised by X-ray crystallography. The syntheses and X-ray crystal structure analysis of Pt₄ aggregates formed with amide α,ω-dialkylating agents with longer spacer atoms, o- and p-ClCH₂C(O)NHC₆H₄NHC(O)CH₂Cl through the intermolecular linking of two [Pt₂(μ-S)₂(PPh₃)₄] complexes is also reported.
Chapter five is the investigation of the immobilisation of [Pt₂(μ-S)₂ (PPh₃)₄] on electrophilic polymer supports. Following the reactivity of [Pt₂(μ-S)₂(PPh₃)₃] with electrophiles established in chapter two a monomeric electrophilic unit 3-chloropropyltetraethoxysilane 5.1a reacted 1.1 to give 5.1b.BPh₄. Further investigations to immobilised 1.1 on solid polymer supports through the alkylation of one of the sulfide centres with electrophilic polymers, Merrifield’s resin 5.2a, 3-bromopropylpolysiloxane 5.3a 3-chloropropyl silica 5.4a and 3-chloropropyl controlled pore glass 5.5a were done. This gave the corresponding immobilised products which is generally represented as [Pt₂(μ-S)(μ-SCH₂R--P )(PPh₃)₄] (where R = phenyl or -CH₂CH₂- groups). The immobilisation of 1.1 was also achieved through phosphine exchange reactions on polymers, a polyethertriamine phosphine derivative 5.6a and diphenylphosphine polystyrene 5.8a. The products were characterised by Scanning Electron Microscopy, solid state ³¹P{H} (CP MAS) NMR, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Photoelectron Spectroscopy (XPS).

text: An Investigation of the Multifunctional Alkylation Chemistry of [Pt₂(μ-S)₂(PPh₃)₄] This thesis presents the studies on the multifunctional alkylation of the metalloligand [Pt₂ (μ-S)₂(PPh₃)₄] 1.1. Multifunctional organic groups which include semicarbazone and thiosemicarbazone, urea, isocyanate, guanidine, ketones and amides react with 1.1 to generate the corresponding functionalised derivatives containing thiolate ligands produced by alkylation of one or both sulfide centres. Polymers with suitable electrophilic branches also react to immobilise 1.1. By using Electrospray Ionisation Mass Spectrometry (ESI-MS) as the monitoring technique, [Pt₂ (μ-S)₂(PPh₃)₄] was employed as a productive template for structurally and chemically diverse thiolate-platinum complexes. Before this study, 1.1 was known to be one of the best building blocks for multimetallic molecules through the exceptional ligating ability of the two sulfide centres to virtually any transition and main group metal fragment. However, extension of the synthetic versatility of 1.1 to multifunctional non-metallic positive centres has only been explored to a lesser extent and thus far less developed.
This thesis is organised into five chapters. Chapter one is the review of literature on [Pt₂ (μ-S)₂(PPh₃)₄] and the development of its chemistry from an efficacious metalloligand for multimetallic assembly to a powerful nucleophile for organic electrophiles. The main geometry and electronic features of 1.1 and analogous complexes were highlighted especially as it affects the dihedral angle (θ) between the two Pt₂S₂ planes in [Pt₂ (μ-S)₂(PPh₃)₄]. The variable reaction modes of 1.1 with different electrophiles were discussed especially as it may affect the less studied multifunctional alkylation. The effectiveness of the ESI-MS as a monitoring tool in the study of 1.1 chemistry is also discussed.
Chapter two details the study of the multifunctional monoalkylation reactions of the aforementioned array of multifunctional organic groups with [Pt₂ (μ-S)₂(PPh₃)₄]. Alkylation reaction of 1.1 with organo-halide of the type R–CH₂-X and R–CH₂CH₂-X (R= organic group and X = Cl or Br) formed thiolate-bridged platinum complexes. The main discovery in this study is that any suitable organic functionality can be incorporated into an electrophile for 1.1. By using the ESI-MS monitoring technique, they successfully reacted with 1.1 to give novel monoalkylated platinum complexes with μ-thiolate ligands of the type [Pt₂(μ-S){μ-SR}(PPh₃)₄](PF₆) which included [Pt₂(μ-S){μ-SCH₂C(=NNHC(O)NH₂)R} (PPh₃)₄](PF₆) in 2.1b•PF₆ (R = Ph) and 2.2b•PF₆ (R = CH₃) and [Pt₂(μ-S){μ-SR}(PPh₃)₄](PF₆) (R = -CH₂C(=NOH)Ph 2.3b•PF₆, -CH₂C(=NNHC(NH₂)NH₂) Ph 2.4b•(PF₆)₂, -CH₂C(=NNHC(S)NH₂)CH₂ 2.5b•PF₆, -CH₂CH₂NHC(O)NHPy 2.6b•PF₆ (Py = o-C₅H₄N), -CH₂CH₂NHC(O)N(CH₂CH₂)₂S 2.7b•PF₆ and -CH₂ C(O)NHC(O)NHCH₂CH₃ 2.8b•PF₆. -CH₂C(═NNHTs)Ph 2.9b•PF₆, -CH₂C(═N NHTs)CH₃ 2.10b•PF₆ (Ts = -SO₂C₆H₄CH₃), -CH₂C(=NHNC(O) Py)Ph (Py = o-C₅H₄N) 2.11b•PF₆ and -CH₂C(=NNHC(O)NH₂)C₆H₄C₆H₅ 2.12b•PF₆. Geome- trical isomers formed with BrCH₂C(NNHAr)C₆H₄Ph 2.13a (Ar = 2,4-dinitrophenyl) was studied and characterised with 2D NMR techniques. The X-ray crystal structures of 2.1b•PF₆, 2.4b•(PF₆)₂, 2.7b•PF₆ and 2.8b•PF₆ are also reported.
Chapter three reports an investigation of conditions that encourage the formation of homo- and heterodialkylated thiolate complexes of the type [Pt₂(μ-SR)₂(PPh₃)4]² + and [Pt₂(μ-SR){μ-SR'}(PPh₃)₄]²+ since these are currently not well understood. The factors were employed in the selective choice of alkylating agents used in the sequential syntheses of homodialkylated derivatives [Pt₂(μ-SCH₂COPh)₂(PPh₃)₄](PF₆)2 3.1b•(PF₆)₂, [Pt₂(μ-SCH₂C(O)pyr)₂(PPh₃)₄](PF₆)₂ (pyr = pyrene) 3.2b•(PF₆)₂ and [Pt₂(μ-SCH₂C(O)cyl)₂(PPh₃)₄](PF₆)₂ (cyl = coumaryl) (3.4b•(PF₆)₂. A major outcome of this study is the successful syntheses of the heterodialkylated derivatives [Pt₂(μ-SCH₂C(O)Ph)(μ-SBu)(PPh₃)₄](PF₆)₂ 3.5b•(PF₆)₂ and {Pt₂(μ-SCH₂COPh)(μ-SCH₂CH₃)(PPh₃)₄}(PF₆)₂ 3.6b•(PF₆)₂ through a sequential alkylation with organo-halide electrophiles. The X-ray crystal structures of 3.1b•(PF₆)₂ and 3.5b•(BPh₄)₂ are reported. The secondary products resulting from the displacement of a PPh₃ by Br- in the synthesis of the heterodialkylated derivatives 3.5b•(PF₆)₂ and 3.6b•(PF₆)₂, [Pt₂(μ-SCH₂C(O)Ph) (μ-SBu)(PPh₃)₃Br](PF₆) 3.5c•PF₆ and [Pt₂(μ-SCH₂COPh)(μ-SCH₂CH₃)(PPh₃)₃ Br](PF₆) 3.6c•PF₆ were also isolated and characterised by ESI-MS and X-ray crystallography.
Chapter four describes the multifunctional intra- and intermolecular bridging dialkylation of 1.1. The variable alkylation mode of α,ω-dialkylating electrophiles, which is dependent on the nature and the number of spacer atoms, was investigated with functionalised electrophiles, ClCH₂C(O)CH₂Cl 4.1a, ClCH₂C(NNHC(O)NH₂) CH₂Cl 4.2a and ClCH₂C(O)NHNHC(O)CH₂Cl 4.3a. A very important novel result is the stabilisation and isolation of an intramolecular bridged five-membered ring derivative 4.1b•PF₆ [Pt₂{μ-SCH₂C(O)CHS}(PPh₃)₄] (PF₆). The reaction of 4.1a with 1.1 in the presence of dilute aqueous NaOH aided the isolation of 4.1b•PF₆ resulting from intramolecular rearrangement of the four membered ring. The semicarbazone derivative 4.2a and diamide 4.3a dialkylated 1.1 by bridging the two sulfide centres to form stable [Pt₂{μ-SCH₂C(NNHC (O)NH₂)CH₂S-μ}(PPh₃)₄](BPh₄)₂ 4.2b•(BPh₄)₂ and Pt₂{μ-SCH₂C(O)NHNH(O) CH₂S}(PPh₃)₄(PF₆)₂ 4.3b•(PF₆)₂. Both 4.1b•PF₆ and 4.2b•(BPh₄)₂ were characterised by X-ray crystallography. The syntheses and X-ray crystal structure analysis of Pt₄ aggregates formed with amide α,ω-dialkylating agents with longer spacer atoms, o- and p-ClCH₂C(O)NHC₆H₄NHC(O)CH₂Cl through the intermolecular linking of two [Pt₂(μ-S)₂(PPh₃)₄] complexes is also reported.
Chapter five is the investigation of the immobilisation of [Pt₂(μ-S)₂ (PPh₃)₄] on electrophilic polymer supports. Following the reactivity of [Pt₂(μ-S)₂(PPh₃)₃] with electrophiles established in chapter two a monomeric electrophilic unit 3-chloropropyltetraethoxysilane 5.1a reacted 1.1 to give 5.1b.BPh₄. Further investigations to immobilised 1.1 on solid polymer supports through the alkylation of one of the sulfide centres with electrophilic polymers, Merrifield’s resin 5.2a, 3-bromopropylpolysiloxane 5.3a 3-chloropropyl silica 5.4a and 3-chloropropyl controlled pore glass 5.5a were done. This gave the corresponding immobilised products which is generally represented as [Pt₂(μ-S)(μ-SCH₂R--P )(PPh₃)₄] (where R = phenyl or -CH₂CH₂- groups). The immobilisation of 1.1 was also achieved through phosphine exchange reactions on polymers, a polyethertriamine phosphine derivative 5.6a and diphenylphosphine polystyrene 5.8a. The products were characterised by Scanning Electron Microscopy, solid state ³¹P{H} (CP MAS) NMR, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Photoelectron Spectroscopy (XPS).

year: 2011

title: Appendix B: Some morphometric parameters of named lakes with areas [greater than or equal to] 1.0 km2, and some smaller lakes, in New Zealand

authors: Lowe, David J.

abstract: Gaps indicate uncertainty or that accurate data are unavailable. Note that lakes with fluctuating levels e.g., those used for hydro-electric purposes, or near coasts have varying parameters. Table based mainly on Irwin (1975) with some data from Cunningham et al. (1953), Irwin (1972), Jolly & Brown (1975), Irwin & Pickrill (1983), Howard-Williams & Vincent 1984, Boswell et al. (1985), Livingstone et al. (1986), N.Z.O.I. Lake Chart series, N.Z. Topographical Map Series NZMS1 (1:63 360) and NZMS26O (1:50 000), and other sources.

text: Appendix B: Some morphometric parameters of named lakes with areas [greater than or equal to] 1.0 km2, and some smaller lakes, in New Zealand Gaps indicate uncertainty or that accurate data are unavailable. Note that lakes with fluctuating levels e.g., those used for hydro-electric purposes, or near coasts have varying parameters. Table based mainly on Irwin (1975) with some data from Cunningham et al. (1953), Irwin (1972), Jolly & Brown (1975), Irwin & Pickrill (1983), Howard-Williams & Vincent 1984, Boswell et al. (1985), Livingstone et al. (1986), N.Z.O.I. Lake Chart series, N.Z. Topographical Map Series NZMS1 (1:63 360) and NZMS26O (1:50 000), and other sources.

year: 1987-01-01

title: Enabling conditions for professional development of te reo Māori teachers

authors: Franken, Margaret

subjects: Māori language teachers

abstract: The paper outlines a professional development programme for secondary school teachers of te reo Māori (under the auspices of Te Hiringa i te Mahara) conducted by a language teacher educator and an expert in Māori bilingualism and biliteracy. While the principles underpinning the programme reflect a strong task-based
orientation, the programme approached development needs for the teachers from the point of view of understanding “enabling conditions” (Franken, Rau, Ngata & Parata, n.d.) for effective language learning and teaching (see also Ellis, 2005),
rather than understanding task based learning and teaching per se. The programme drew on the current practices of the teachers and made use of epistemology of Māori language and Māori language learning. The paper presents observations from monitoring data collected during the programme supporting the claim that such an approach to the professional development of language teachers promotes a strong knowledge base and pedagogical reasoning skills (Richards, 1998), and in particular for te reo Māori teachers, fosters a sense of their own professional identity.

text: Enabling conditions for professional development of te reo Māori teachers The paper outlines a professional development programme for secondary school teachers of te reo Māori (under the auspices of Te Hiringa i te Mahara) conducted by a language teacher educator and an expert in Māori bilingualism and biliteracy. While the principles underpinning the programme reflect a strong task-based
orientation, the programme approached development needs for the teachers from the point of view of understanding “enabling conditions” (Franken, Rau, Ngata & Parata, n.d.) for effective language learning and teaching (see also Ellis, 2005),
rather than understanding task based learning and teaching per se. The programme drew on the current practices of the teachers and made use of epistemology of Māori language and Māori language learning. The paper presents observations from monitoring data collected during the programme supporting the claim that such an approach to the professional development of language teachers promotes a strong knowledge base and pedagogical reasoning skills (Richards, 1998), and in particular for te reo Māori teachers, fosters a sense of their own professional identity.

year: 2009