Studies into the effects of hexa-hapto spectator ligands on the chemistry of ruthenium.

This thesis describes the results of investigations into the chemistry of ruthenium complexes of hexa-hapto spectator ligands. Two specific systems have been examined. Chapters 2-5 describe aspects of the chemistry of the ruthenium(IV) chloride bridged compound [{Ru(η3:η3-C10H16)Cl(µ-Cl)}2] which contains the n3:n3-bis(allyl) ligand 2,7-dimethylocta-2,6-diene-1,8-diyl, derived from the ruthenium trichloride mediated dimerisation of isoprene. In Chapters 6 and 7 the reactivity of arenes and cyclohexadienes is examined in ruthenium complexes of the polyaromatic η6-spectator [2.2]paracyclophane. Chapter 1 offers a general introduction to arene and allyl transition metal chemistry and attempts to place the results reported herein into a wider context. In Chapter 2 the reactions of the bis(allyl)ruthenium(IV) chloride bridged dimer [{Ru(η3:η3-C10H16)Cl(µ-Cl)}2] with amines and polypyridines are examined. Bridge cleaved amine adducts of formulae [Ru(η3:η3-C10H16)Cl2L] or [{Ru(η3:η3-C10H16)Cl2}2(?-L)] (L = PhNH2, o-pda, p-pda) are reported and the diastereoisomerism of the binuclear compounds examined. The mononuclear chelate compounds [Ru(η3:η3-C10H16)Cl(L- L)][Bp4] (L-L = 2,2'-diaminodiphenyl, 2,2'-bipyridyl, 1,10-phenanthroline) and [Ru(?3-?3-C10H16)(terpy)][BF4]2 are formed from treatment of the starting material with Ag[BF4] and the appropriate ligand. Chapter 3 reports a number of carboxylato compounds of ruthenium(IV). These products occur as either 1 : 1 bidentate chelates [RU(η3:η3-C10H16)CLO2CR)] (R = Me, CH2F, CH2Cl) or 1 : 2, monodentate carboxylato aqua complexes [Ru(η3:η3-C10H16)(O2CR)2(OH2)] (R = CH2CI, CH2F, CHCl2, CHF2, CCl3, CF3). The electronic properties of the carboxylato ligand are found to be crucial to the product stoichiometry. The analogous thiocarboxylato compounds [Ru(η3:η3-C10H16)]Cl(OSCR)] (R = Me, Ph, tBu) exhibit bidentate coordination and exist as two alternative geometric isomers with the sulphur located either axially or equatorially. In the case where R = Me coordination is found to proceed via a two step process involving the monodentate thioacetic acid adduct [Ru(η3:η3-C10H16)]Cl2(S(OH)CMe}]. The related nitrato compounds [Ru(η3:η3-C10H16)Cl(NO3)] and [Ru(η3:η3-C10H16)](NO3)2] are also reported. In the latter case the "semi-chelating" nitrato ligands readily become monodentate in the presence of two electron ligands to give adducts [Ru(η3:η3-C10H16)(NO3)2L] (L = CO, py). Chapter 4 reports a range of 2-pyridinol and pyridine-2-thiol compounds of ruthenium(IV) of form [Ru(η3:η3-C10H16))Cl(pyrX)] (X = O, S) and related species. These compounds all exhibit axial and equatorial geometrical isomerism and a method based on 1H NMR spectroscopy is described for distinguishing between the two forms. In Chapter 5 a range of bi- and trinuclear compounds of ruthenium(IV) are described and their inherent diastereoisomerism studied. The bridge-cleaved adducts [{Ru(η3:n3-C10H16)Cl2}2(µ-pyz)] and [{Ru(η3:η3-C10H16)Cl2}n(µ-tra)] (n = 1, 2, 3) are reported along with the thiocyanato, carboxylato and nicotinato bridged compounds [{Ru(η3:η3-C10H16)C1(µ-SCN)}2], [{Ru(η3:η3-C10H16)Cl}2(µ-O4R)] (R = C2, C3,H2) and [RU2(η3:η3-C10H16)2CL3(µ-NC5H4CO2)]. In Chapter 6 the single nucleophilic addition reactions of simple anions N- (N = H, CN, OMe, Me) to unsymmetrical bis(arene)ruthenium(II) compounds [Ru(η6-arene)(η6-[2.2]paracyclophane)]2+ (arene = C6H6, p-MeC6H4CHMe2, l,4-(CHMe2)2C6H4, C6Me6, C16H16) are examined. It is found that the cyclophane acts as a non-innocent spectator ligand, directing nucleophiles onto other arenes coordinated to the same metal centre to give the cyclohexadienyl compounds [Ru(η6-[2.2]paracyclophane)(η5-C6R6N)]+. Chapter 7 describes the extension of the work reported in Chapter 6 to double nucleophilic addition reactions to give ruthenium(0) compounds of general form [Ru(η6-[2.2]paracyclophane)(η4-diene)]. The reactivity of these Ru(0) species towards H[BF4] is examined resulting in a range of novel agostic compounds. Mechanistic aspects are investigated by a range of deuteriation studies. Finally, Chapter 8 offers some conclusions on what has been learned about the effects the two spectator ligands studied have on the chemistry of ruthenium

Modulating the Hydration Behaviour of Calcium Chloride by Lactam Complexation

Complexation of calcium chloride with bis(lactam) ligand L1 allows the formation of both an unstable anhydrous complex, an aqua complex {[Ca2(μ-L1)2(H2O)9]Cl4]}n (1) and a related hydrate incorporating additional lattice water of crystallization {[Ca(μ-L1)(H2O)5]Cl2·H2O}n (2). Related mono(lactam) L2 does not form aqua complexes but the anhydrous complex {[CaCl2(μ-L2)2]}n (3), is highly deliquescent. An unusual ethanol solvate is also reported {[CaCl2(L2)(EtOH)]}n (4)

Guest inclusion by Borromean weave coordination networks

Reaction of N,Nʺ-ethylene-1,2-diylbis(3-pyridin-3-ylurea) (L) with AgNO3 in a variety of solvents gives a total of five 2-D Borromean weave coordination polymer networks that adopt three structural types depending on the interactions to the solvent pocket. The Borromean network is of formula [Ag2(L)3](NO3)2 ·solvent where the solvent is either a cluster of water molecules, mixtures of water and acetonitrile, water and methanol or chloroform and methanol. The Borromean structure is a thermodynamic sink and under fast crystallization conditions an alternative 2 + 2 metallomacrocycle forms that can result in metallogel formation. The metallogel structure transforms into the crystalline Borromean network over time

Anion Hydrogen Bonding from a ‘Revealed’ Urea Ligand

Hydrogen bonding from a urea group to hydrogen bond acceptor anions can adopt either R_2^1 (6) or R_2^2 (8) motifs depending on the proximity of hydrogen bond acceptor atoms. However, for the sterically bulky and weaker hydrogen bond acceptor triflate anion, hydrogen bond acceptor polymorphism is observe

Conserved hydrogen bonding in tetrahydrocarbazolone derivatives: influence of solution-state assembly on crystal form nucleation

Two tetrahydocarbazolone derivatives were found to show multiple unsolvated crystal forms. A persistent dimer motif was detected in solution by FTIR spectroscopy that is maintained in the kinetic crystal forms. Rationally introduced steric bulk induces the formation of a more stable catemeric form

What Has Carbamazepine Taught Crystal Engineers?

The antiepilepsy drug carbamazepine is one of the most studied pharmaceuticals in the world. The rich story of its solid forms, cocrystals, and formulation is a microcosm of the topical world of pharmaceutical materials. Understanding carbamazepine has required time, money, and dedication from numerous researchers and pharmaceutical companies worldwide. This wealth of knowledge provides the opportunity to reflect on progress within the crystal engineering field in general. This Perspective covers the extensive solid form landscape of carbamazepine and applies these examples to discuss and answer fundamental questions in the discipline. The story encompasses screening methods, computational solid form discovery, the power and influence of crystal engineering in understanding and controlling crystals and the amorphous state, and the environmental legacy of modern pharmaceuticals. This broad but in-depth analysis of carbamazepine is a vehicle into modern crystal engineering, not only in its own right but across the spectrum of organic materials science and pharmaceutical formulation. Discoveries of carbamazepine demonstrate the potential richness in the materials chemistry of every drug

Gelation by histidine-derived ureas

A series of l-histidine-derived monoureas are described which exhibit versatile organogelation peroperties when the substituent directly attached to the urea is an aliphatic group. Arylureas exhibit a tendency to bind chloride anion

N-alkyl pyrrolidone ether podands as versatile alkali metal ion chelants

This work explores the coordination chemistry of a bis(pyrrolidone) ether ligand. Pyrrolidones are commercially important functional groups because of the high polarity and hence high hydrophilicity and surface affinity. An array of alkali metal ion complexes of a podand bearing two pendant pyrrolidone functionalities, namely 1-{2-[2-(2-oxo-pyrrolid-1-yl)-ethoxy]-ethyl}-pyrrolid-2-one (1) are reported. Reaction of this ligand with sodium hexafluorophosphate gives two discrete species of formulae [Na(1)2]PF6 (3) and [Na3(H2O)2(μ-1)2](PF6)3 (4), and a coordination polymer {[Na3(μ3-1)3(μ2-1)](PF6)3}n (5). The same reaction in methanol gives a 1 : 1 complex, namely [Na2(μ-1)2(MeOH)2](PF6)2 (6). Use of tetraphenyl borate as a less coordinating counter ion gives [Na2(1)2(H2O)4](BPh4)2 (7) and [Na2(1)4](BPh4)2 (8). Two potassium complexes have also been isolated, a monomer [K(1)2]PF6 (9) and a cyclic tetramer [K4(μ4-H2O)2(μ-1)4](PF6)4 (10). The structures illustrate the highly polar nature of the amide carbonyl moiety within bis(pyrrolidone) ethers with longer interactions to the ether oxygen atom. The zinc complex is also reported and {[ZnCl2(μ-1)]}n (11) exhibits bonding only to the carbonyl moieties. The ether oxygen atom is not necessary for Na+ complexation as exemplified by the structure of the sodium complex of the analogue 1,3-bis(pyrrolid-2-on-1-yl)- butane (2). Reaction of compound 1 with lithium salts results in isolation of the protonated ligand

Selective gelation of N-(4-pyridyl)nicotinamide by copper(II) salts

We report the selective gelation properties of the copper(II) complexes of N-(4-pyridyl)nicotinamide (4PNA). The morphology of the xerogels was examined by scanning electron microscopy (SEM). The correlation between the X-ray powder diffraction (XRPD) pattern of the xerogels and the single crystal structure of the copper(II) acetate complex suggests that the single crystal X-ray data represent a good structural model for the gel fibers, and that gelation arises from the presence of a 1D hydrogen-bonded chain between gelator amide groups and coordinated anions, while the presence of strongly bound water in non-gelator systems results in the formation of more extensively hydrogen-bonded crystalline networks. The selective gelation of all the copper(II) salts compared to the other metal salts may be attributed to the Jahn–Teller distorted nature of copper(II), which weakens water binding in all copper(II) salts