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Studies were conducted to explore the electronic properties of the cyclometalated (C^N) complexes of iridium and platinum metals with catechol ligand. The complexes were observed to exhibit a reversible reduction of the semiquinone form to the catechol form of the ligand and an irreversible oxidation to the unstable quinone form of the ligand.

The syntheses and systematic X-ray investigations of complexes [Cp.sub.2]Nb(SiY[Me.sub.2])(H)(SiX[Me.sub.2]) and the neutron diffraction (ND) studies of complexes [Cp.sub.2]Nb-(SiH[Me.sub.2](H)(SiCl[Me.sub.2]) and [Cp.sub.2]Nb(SiH[Me.sub.2])(H)(SiBr[Me.sub.2]) is reported. The complexes show the largest structural distortions for the silyl groups substituted by heavy halogen atoms.

The crystal structure of NF4BF4 was verified at different temperatures. The low-temperature X-ray structure and solid-state [.sup.19.F] MAS NMR spectra are in line with the conclusions reached from the vibrational spectra, that solid [NF4.sup.} salts contain only tetrahedral [NF4.sup.} cations.

A series of cationic bis-cyclometalated iridium(III) complexes are synthesized and their electrochemical, photophysical, electroluminescent properties are studied. The complexes are found to be luminescent both in a fluid solution and as neat solids at 298 K, while single-layer electroluminescent devices that give blue, green, and red electroluminescence are also fabricated.

The approaches are reported to achieve efficient blue to near-UV emission from triscyclometalated iridium(III) materials. The approach to tuning the photophysical properties of cyclometalated Ir complexes investigated in the study involved the control of the relative energies of emissive and non-emissive excited states.

The synthesis and photophysical characterization of a series of (N,C(super 2')-(2-para-tolylpyridyl)2Ir(LL') [tpy)2Ir(LL')] (LL' = 2,4-pentanedionato (acac), bis(pyrazolyl)borate ligands and their analogues, diphosphine chelates and tert-butylisocyanide (CN-t-Bu) are reported. The electrochemical and photophysical properties of the (typ)2Ir(LL') complexes are discussed in detail.

Molecular dynamics are used to investigate the instantaneous structure of a fourth generation dendimer of propolene amine dissolved in CH2Cl2, and the same system upon the subsequent encapsulation of several eosin dyes. Calculations in a cubic box with upto `3500 solvent molecules and maximum of 12 eosins show that one of the effects of the presence of the guest molecules is to 'close' the structure of the box where they are contained.

The methods for tris-cyclometalates are reported, which demonstrate that controlling the reaction conditions could impart significant control in product configuration. For all the cyclometalating ligands studied, there is a preference to form the facial isomers at high temperatures and the meridional isomers at lower temperatures.

Research has been conducted on the square planar platinum complexes. The synthesis, photolysis and electrochemistry of these cyclometalated complexes have been investigated and the details are presented.

Crystal structures of fluro-substituted carbocations and of As(sub2)F(sub11-) anions are reported.

Ninhydrin reacts with aromatic compounds in acid solution to produce condensation products. In sulfuric acid, ninhydrin reacts with aromatic compounds to yield 2,2-diaryl-1,3-indanediones, In superacidic triflic acid, it reacts with arenes to produce 3-(diarylmethylene)isobenzofuranones (3a-3) Products 3a-e are suggested to have formed through a condensation and rearrangement involving dicationic intermediates.

The stereochemical course of the hydration of trans-crotonobetaine to L-(-)-carnitine by the L-carnitine dehydratase enzyme was determined using single-crystal neutron diffraction. X-ray analysis of ((Chsub3)sub3N-Chsub2-CH(OH)-CHsub2-COOH)+(AuC1sub4)-, an undeuterated carnitinium salt, confirmed the configuration of L-(-)-carnitine at the Csub3 position. Neutron analysis showed that the CHD group had the absolute R configuration at position Csub2.

The slow interconversion of [FeIII(TF4TMAP)(H2O)2]5+ and [FeIII(TF4TMAP)OH]4+ takes place mainly through bimolecular reaction between the aqua and hydroxo forms with k = 1.6 x 10(supra6) M-1 s-1 (298 K) and Ea = 6.7 plus or minus 0.4 kcal mol-1. Exchange of a proton, motion of the iron into or out of the porphyrin plane and addition or loss of a coordinated water are all involved in the interconversion between [FeIII(TF4TMAP)OH]4+ and [FeIII(TF4TMAP)(H2O)2]5+.

The determination of the absolute R configuration of (+)-ethanol-1-d, (+)-CH3-CHDOH as the (-)-camphanate ester was established through the use of single-crystal neutron diffraction techniques. Neutron analysis of its (-)-(1S)-camphanate ester indicated that the absolute configuration of (+)-ethanol-1-d was indeed R. It was further indicated that (R)-(+)-ethanol-1-d has an optical rotation opposite to that of (R)-(-)-propanol-1-d,(R)-(-)-butanol-1-d, and (R)-(-)-neopentyl-1-d alcohol [(R)-2,2-dimethylpropanol-1-d].

The phase change in phases II and II of N(CH3)4IO4 is a result of the commencement of free ion rotation rather than the rotational oscillation axes' positional disorder, according to research of its Raman spectra and crystal structures. The finding is in agreement with L. Pauling's initial proposal. In high temperature phase I, both ions are believed to be rotationally disordered; in room-temperature phase II, the lesser counterion is rotationally disordered while the greater ion is ordered; in low-temperature phase III, the cation and anion are both ordered.

The interaction between copper(II) and the fulleride(1-) anions of pyrrolidine-functionalized C60 derivatives was analyzed by electron paramagnetic resonance (EPR) to characterize spin-spin coupling reactions. EPR analysis of bifullerenes indicated the presence of chromophore/chromophore interactions which induced the perturbation of the electronic structure of a functionalized C60 moiety by a nearby porphyrin or C60 chromophore. Furthermore, the bifullerenes exhibited triplet features due to intramolecular ball-to-ball spin interactions.

X-ray crystallograhic analysis was done to characterize the cumyl cation, 2-phenyl-2-propyl. The results revealed that the tertiary cation is nearly planar and bears a short C(super +)-C(sub ipso) bond. It was also found that the bond lengths in the phenyl ring coincide with the observed strong benzylic delocalization. The C(super +)-CH3 bonds exhibited weak C-H hyperconjugation and the phenyl rings were found arranged in infinite stacks within which they are shifted against each other.

Anhydrous 1-methylhexamethylenetetramine fluoride was produced by either halogen exchange between the corresponding iodide and AgF or by a single-step, one-pot, self-assembling synthesis from aqueous CH3NH2, HF, formaldehyde and NH3. It was characterized by NMR and vibrational spectroscopy. Its hydrate underwent a Sommelet-type ring opening and coupling reaction at 70 degrees C to produce a possible cryptand system composed of two bicyclic triazine groups that are linked through a methylene bridge and have eight ternary nitrogen atoms.

The N (1') site and the phosphate group of Zn2+, Cd2+ and Hg2+ complexes with 2-(alpha-hydroxybenzyl)thiamine monophosphate chloride or (LH)+Cl- serve as metal binding sites. The N (1') group in the pyrimidine ring of HgL2Cl2 exhibited metal phosphate binding reactions based on P solid-state nuclear magnetic resonance spectroscopy. The crystal structures of (LH)+Cl- and HgL2Cl2 are composed of four molecules per unit cell. Electrostatic and stacking interactions together with hydrogen bonds stabilize the water molecules of the complexes.

Nickel tetrakis(N-methyl-4-pyridiniumyl)porphyrin(NiT4-N-MePyP4+) was shown to bind axial bonds more strongly than nickel tetrakis(2,3,5,6-tetrafluoro-N,N,N-trimethyl-4-aniliniumyl)-porphyrin (NiTF4TMAP+). Solution chemistry and crystal structure of the complexes revealed that the four coordinate (NiT4-N-MePyP4+) is in equilibrium with the six coordinate Ni(H2O)2TF4-TMAP4+ in aqueous solution and creates a hydrophobic effect, which strengthens porphyrin interactions in the solution.

The NMR study of the rotational isomers of tetrakis(N-methyl-2-pyridiniumyl)porphyrin shows the presence of N-methyl groups determines the rotational disposition of the next N-methylpyridiniumyl groups. The porphyrins have a regular, sandwich array structure. Two different types of protonated ferrocyanide anions are connected respectively with the water-rich region and water-poor region of the structure. The two type of ferrocyanide ions are linked through the hydrogen-bonded water.