Peter Neil Horton

Upon metal coordination, the upper rim modification of the Schiff base ligand 2-methoxy-6-((methylimino)methyl)phenol gives rise to a new family of [M(II)₇] (M = Co, Ni, Zn) pseudo metallocalix[6]arenes in the form of [Co(II)₇(OMe)₆(L₃)₆](NO₃)₂·2H₂O·3MeOH (1), [Ni(II)₇(OMe)₆(L₃)₆](NO₃)₂·2H₂O (4), [Zn(II)₇(OH)₂(OMe)₄(L₃)₆](NO₃)₂·10H₂O·4MeOH (5) and [Zn(II)₇(OMe)₆(L₄)₆](NO₃)₂·13H₂O·10MeOH (6), where L₃H = 2-methoxy-4-phenyl-6-[(methylimino)methyl]phenol and L₄H = 2-methoxy-4-tolyl-6-[(methylimino)methyl]phenol. The upper rim functionalisation provides this family with extensions to their molecular cavity walls when compared to their previously reported siblings. Attempts at encapsulating guest moieties (e.g., C₆₀) unexpectedly give rise to the dimeric complex [Co(II)Co(III)(L₃)₃(NO₃)₂]·H₂O (3).

Upon metal coordination, the upper rim modification of the Schiff base ligand 2-methoxy-6-((methylimino)methyl)phenol gives rise to a new family of [M(II)₇] (M = Co, Ni, Zn) pseudo metallocalix[6]arenes in the form of [Co(II)₇(OMe)₆(L₃)₆](NO₃)₂^.H₂O^.3MeOH (1), [Ni(II)₇(OMe)₆(L₃)₆](NO₃)₂^.2H₂O (4), [Zn(II)₇(OH)₂(OMe)₄(L₃)₆](NO₃)₂^.4MeOH^.10H₂O (5) and [Zn(II)₇(OMe)₆(L₄)₆](NO₃)₂^.10MeOH^.13H₂O (6), where L₃H = 2-methoxy-4-phenyl-6-[(methylimino)methyl]phenol and L₄H = 2-methoxy-4-tolyl-6-[(methylimino)methyl]phenol). The upper rim functionalisation provides this family with extensions to their molecular cavity walls when compared to their previously reported siblings. Attempts at encapsulating guest moieties (e.g. C₆₀) unexpectedly give rise to the monometallic complex [Co(II)Co(III)(L₃)₃(NO₃)₂]^.H₂O (3).

The family of N,N-dimethylaminomethylferrocene compounds is one of the most important in ferrocene chemistry. They serve as precursors for a range of anti-malarial and anti-tumour medicinal compounds, in addition to being key precursors for ferrocene ligands in the Lucite alpha process. A brief discussion on the importance and synthesis of N,N-dimethylaminomethyl-substituted ferrocenes preludes the synthesis of the new ligand, 1,1′,2,2′-tetrakis-(N,N-dimethylaminomethyl)ferrocene. The crystal structure of this compound is reported, and a comparison is made with its disubstituted analogue, 1,2-bis-(N,N-dimethylaminomethyl)ferrocene. The tetrahedral nickel dichloride complexes of both these ligands have been crystallographically characterised. Finally, a pointer to future research in the area is given, which includes a discussion of a new method to extract ferrocenylmethylamines from mixtures using additives and a new synthetic avenue from substituted cyclopentadiene itself.

The family of N,N-dimethylaminomethylferrocenes is one of the most important in ferrocene chemistry. They serve as precursors for a range of anti-malaria and anti-tumour medicinal compounds in addition to being key precursors for ferrocene ligands in the Lucite alpha process. A brief discussion on the importance of, and the synthesis of N,N-dimethylaminomethyl-substituted ferrocenes preludes the synthesis of the new ligand 1,1´,2,2´-tetrakis-(N,N-dimethylaminomethyl)ferrocene. The crystal structure of this compound is reported and a comparison is made with its disubstituted analogue, 1,2-bis-(N,N-dimethylaminomethyl)ferrocene. The tetrahedral nickel dichloride complexes of both these ligands have been crystallographically characterised. Finally, a pointer to future research in the area is given which includes a discussion of a new method to extract ferrocenylmethylamines from mixtures using additives and a new synthetic avenue from substituted cyclopentadiene itself.

The reaction of the bulky ligand 1,2-bis-(di-tert-butylphosphinomethyl)benzene, 1 with [Ni(DME)Cl₂], 3, DME = 1,2-dimethoxyethane, at room temperature over extended periods, affords the new blue Zwitterionic complex [2-(C₆H₄-CH₂P(H)^tBu₂-1-(CH₂P^tBu₂NiCl₃)], 4, which contains a phosphonium group and an anionic nickel trichloride. This complex decomposes in alcohols such as methanol and the solution turns yellow. A discussion of the possible mechanism leading to the observed product is presented. Key to this is identification of the source of the phosphonium proton, which we speculated to arise from trace water in the initial nickel complex. To prove that trace water was present in [Ni(DME)Cl₂], a sample of this precursor was reacted under similar condition with anhydrous DMF alone. In addition to the known complex [Ni(DMF)₆)]²⁺[NiCl₄]²⁻, 5, we identified the trans-diaqua complex [Ni(Cl)₂(H₂O)₂(DMF)₂], 6, which proved the presence of trace water. Interestingly in dimethylformamide, [2-(C₆H₄-CH₂P(H)^tBu₂-1-(CH₂P^tBu₂NiCl₃)] exhibits thermochromic properties: an solution that is pale blue at ambient temperature reversibly changes colour to yellow upon cooling. This behaviour is specific to DMF and is related to the solvato-chromic behaviour exhibited by related DMF–nickel complexes. A discussion of the NMR spectra of compound 4 in a range of solvents is presented. The structures of the previously prepared molybdenum complex, [1,2-(C₆H₄-CH₂P^tBu₂)₂Mo(CO)₄] and the bis-(phosphine sulphide) of the ligand, [1,2-(C₆H₄-H₂P(S)^tBu₂)₂], 5, are described for structural comparative purposes.

The reaction of the bulky ligand 1,2-bis-(di-tert-butylphosphinomethyl)benzene,1 with [Ni(DME)Cl₂], 3, DME = 1,2-dimethoxyethane, at room temperature over extended periods, affords the new blue Zwitterionic complex [(1,2-C₆H₄-CH₂P^tBu₂-2-C₆H₄-CH₂P(H)^tBu₂)₂NiCl₃], 4, which contains a phosphonium group and an anionic nickel trichloride. This complex decomposes in alcohols such as methanol and the solution turn yellow. A discussion of the possible mechanism leading to the observed product is presented. Key to this is identification of the source of the phosphonium proton, which we speculated to arise from trace water in the initial nickel complex. To prove that trace water was present in [Ni(DME)Cl₂] a sample of this precursor was reacted under similar condition with anhydrous DMF alone. In addition to the known complex [Ni(DMF)₆)]²⁺[NiCl₄]^2-, 5, we identified the trans-diaqua complex [Ni(Cl)₂(H₂O)₂(DMF)₂], 6, which proved the presence of trace water. Interestingly in dimethylformamide [(1,2-C₆H₄-CH₂P^tBu₂-2-C₆H₄-CH₂P(H)^tBu₂)₂NiCl₃] exhibits thermochromic properties: an ambient temperature pale blue solution changes colour reversibly to yellow on cooling. This behaviour is specific to DMF and is related to the solvato-chromic behaviour exhibited by related DMF nickel complexes. A discussion of the NMR spectra of compound 4 in a range of solvents is presented. The structures of the previously prepared molybdenum complex, [1,2-(C₆H₄-CH₂P^tBu₂)₂Mo(CO)₄] and the bis-(phosphine sulfide) of the ligand, [1,2-(C₆H₄-H₂P(S)^tBu₂)₂], 5, are described for structural comparative purposes.

A series of nickel (II) bis-phosphine organometallic complexes along with two pseudo [M₇] (M = Ni(II), Zn(II)) metallocalix[6]arene complexes and a dysprosium acetate coordination polymer have each been crystallised in the presence of localized magnetic fields set up using neodymium magnets, using custom made Magnetic Crystallization Towers (MCTs). In all cases, whether the product complex is diamagnetic or paramagnetic, a complex spatial patterning of the crystals occurs based on the orientation of the magnetic field lines. When using magnetic block towers, the crystallization generally occurs adjacent to the magnet face. The effects of nucleation and solution concentration gradients on the crystallization process are also explored. These observations show how the crystallization process is affected by magnetic fields and thus these results have far-reaching effects which most certainly will include crystallization and ion migrations in biology.

The crystallization of nickel (II) bis-phosphine and nickel and zinc cluster complexes have been carried out in localized magnetic fields set up using neodymium magnets, including custom made Magnetic Crystallization Towers (MCTs). In all cases, whether the product complex is diamagnetic or paramagnetic, a complex spatial patterning of the crystals occurs based on the orientation of the magnetic field lines. The effects of nucleation, and solution concentration gradients on the crystallization process are also explored. These observations therefore show how the crystallization process is affected by magnetic fields and thus these results have far-reaching effects which most certainly will include crystallization and ion migrations in biology.

In this paper, the clean high yielding, synthesis, and structure of the tetraphosphine ligand, 1,1′,2,2′-tetrakis-(di-isopropyl-phosphino)ferrocene, (tdipf), is described. In addition, improved synthesis methods for 1,1′,2,2′-tetrakis(diphenylphosphino)ferrocene, (tppf), and 2,2′-bis-(diphenylphosphino)-1,1′-dibromoferrocene are also reported, and the synthetic method is generalised to include the synthesis of 3,3′-bis-(diphenylphosphino)-1,1′,2,2′-tetrabromoferrocene. The related ligands 2,2′-bis-(iso-propylphosphino)-1,1′-bis-diphenylphosphinoferrocene (diprdppf) and 2,2′-bis-(di-isopropylphosphino)-dibromoferrocene have also been prepared and characterised. The crystal structure of the square planar bimetallic nickel (II) dichloride of tdipf is also described, together with a brief NMR study investigating the synthesis of this and related metal complexes. The crystal structures of the palladium and platinum dichloride complexes of 2,2′-bis-(di-isopropylphosphino)-1,1′-dibromoferrocene, bpdbf, are also discussed in the context of comparison with previously known crystal structures in the same general family. A general discussion on the synthetic methodology is given, along with indications for future research that other researchers might explore.

The clean high yielding, synthesis and structure of the tetraphosphine ligand, 1,1´,2,2´-tetrakis-(di-isopropyl-phosphino)ferrocene, (tdipf), is described. In addition, an improved synthesis of the 1,1´,2,2´-tetrakis(diphenylphosphino)ferrocene, (tppf) and 2,2´-bis-(diphenylphosphino)-1,1´-dibromoferrocene are also reported and the synthetic method is generalised to include the synthesis of 3,3’-bis-(diphenylphosphino)-1,1´,2,2´-tetrabromoferrocene. The related ligands 2,2´-bis-(iso-propylphosphino)-1,1´-bis-diphenylphosphinoferrocene (diprdppf) and 2,2´-bis-(di-isopropylphosphino)-dibromoferrocene have also been prepared and characterised. The crystal structure of the square planar bimetallic nickel (II) dichloride of tdipf is also described, together with a brief NMR study investigating the synthesis of this and related metal complexes. The crystal structures of the palladium and platinum dichloride complexes of 2,2’-bis-(di-isopropylphosphino)-1,1’-dibromoferrocene, bpdbf, are also discussed in the context of comparison with previously known crystal structures in the same general family. A general discussion on the synthetic methodology is given and pointers to future research other researchers might explore.