Variational Monte Carlo study of core-valence separation schemes for first-row atoms and positive ions /

All-electron partitioning of wave functions into products ^core^vai of core and valence parts in orbital space results in the loss of core-valence antisymmetry, uncorrelation of motion of core and valence electrons, and core-valence overlap. These effects are studied with the variational Monte Carlo method using appropriately designed wave functions for the first-row atoms and positive ions. It is shown that the loss of antisymmetry with respect to interchange of core and valence electrons is a dominant effect which increases rapidly through the row, while the effect of core-valence uncorrelation is generally smaller. Orthogonality of the core and valence parts partially substitutes the exclusion principle and is absolutely necessary for meaningful calculations with partitioned wave functions. Core-valence overlap may lead to nonsensical values of the total energy. It has been found that even relatively crude core-valence partitioned wave functions generally can estimate ionization potentials with better accuracy than that of the traditional, non-partitioned ones, provided that they achieve maximum separation (independence) of core and valence shells accompanied by high internal flexibility of ^core and Wvai- Our best core-valence partitioned wave function of that kind estimates the IP's with an accuracy comparable to the most accurate theoretical determinations in the literature.

The crystal and molecular structure of 18-Crown-6 HgC12 and 18-Crown-6 Cdc12

Hg(18-Crown-6)C12 and Cd(18-Crown-6)C12 are isostructura1, space group Cl~ Z = 2. For the mercury compound, a = 10.444(2) A° , b = 11. 468(1) A° , c = 7.754(1) A° , a = 90.06(1)°, B = 82.20(1)°, Y = 90.07(1)°, Dobs = 1.87, Dca1c = 1.93, V = 920.05 13, R = 4.66%. For the cadmium compound, 000 a = 10.374(1) A, b = 11.419(2) A, c = 7.729(1) A, a = 89.95(1)°, B = 81.86(2)°, Y = 89.99(1)°, Dobs = 1.61, Dcalc = 1.64, V = 906.4613, R = 3.95%. The mercury and cadmium ions exhibit hexagonal bipyramidal coordination, with the metal ion located on a centre of symmetry in the plane of the oxygen atoms. The main differences between the two structures are an increase in the metal-oxygen distance and a reduction in the metalchloride distance when the central ion changes from Cd2+ to Hg2+. These differences may be explained in terms of the differences in hardness or softness of the metal ions and the donor atoms.

Who expects what from whom? : a gender based study on expectations and secondary school administration

This study is about expectations and aspirations of secondary school teachers. It is an investigation of why some teachers aspire to become administrators and why some teachers do not. My research compares expectations and existing attltudes regarding aspirations toward administration which are held by three distinct groups within the secondary school system: 1) principals/vice-principals, 2) aspiring teachers, and 3) non-aspiring teachers. This study questions why, in the late 60's, secondary school administration is still predominated by men. The conclusions and recommendations were based on interviews with thirty men and women in the Hamilton Secondary School System. In addltion, Mr. Keith Rielly, Superintendent of Operations, made valuable contributions to my work. The interviews revealed experiences and percept ions of men and women in di scourse about f amil y re lat i onshi ps, educational choices and perceived internal and external barriers which inhiblted or enhanced their decision to aspire to secondary school administration. Candidates spoke about their personal and professional Hves wlth respect to encouragement, perceived images of an administrator, netWOrking and the effect of marriage and children on their careers. Historically, women have not accepted the challenge of administration and It would appear as if this is still the case today. My research suggests that women are under-represented in secondary school administration because of internal and external barriers which discourage many women from aspiring. I conclude that many of women's internal barrlers are reinforced by external roadblocks which prevent women from aspiring to secondory school administration. Thus. many women who do not envision a future in educational administration establish priorities outside the general realm of education. I recommend that males and females recognize that women make valuable contributions to educational theory and design based on their experiences which may be "differene from mole experiences. but just as significant. Mole and female representation in secondary school administration represents a balance between attitudes and behaviours which can not be accomplished when an administrative offlce is dominated by on all ma1e or all female staff.

ESI-MS[n] of anticancer pt[iv] organoamido complexes and their interactions with DNA-model compounds /

The general solution behaviour and" the major fragmentation pathways of the anticanceractive PtIV coordination complexes, trans, trans, cis, cis-[PtCIOH{N(pFC6F4) CH2h(pY)2] (1), trans, cis, cis-[Pt(OH)2{N(p-FC6F4)CH2h(Py)2] (2), trans, cis, cis-[Pt(OH)2{N(p-HC6F4)CH2h(Py)2] (3), trans, trans, cis, cis-[PtCIOH{N(pHC6F4) CH2h(Py)2] (4), and trans, trans, cis, cis-[PtOH(OCH3){N(p-HC6F4)CH2h(PY)2] (5) (Py = pyridine) have been deduced by positive-ion tandem-in-time ESI-MS. Overall, the acquired full-scan, positive-ion ESI-MS spectra of 2, 3, and 5 were characterized by the presence of relatively low-intensity [M+Nar and [M+Kt mass spectral peaks, whereas those of 1 and 4 were dominated by extremely intense [M+Hr peaks. Complexes 2 and 3 were also noted to form [2M+Ht and [2M+Nat dilneric cations. The source of Na + and K+ ions is believed to be the sample, the solvent systems used or the transport line carrying the sample solutions into the ES ion source. Further, the fragmentation pathway of all complexes studied was found to be almost identical with concurrent loss of py and H20 molecules, loss of a {N(p-YC6F4)CH2} (Y = F, H) group and/or concomitant release of the latter group and a py ligand being the most conunon. The photochemical degradation behaviour of 1 and 2 was also investigated using either fluorescent or ultraviolet light and some products of that degradation were positively identified. Altogether, light irradiation of solutions of both complexes resulted in cation cationisation, reductive-elimination, ligand-release, ligand-exchange and ligand-addition reactions. Finally, positive- and negative-ion ESI-MSn spectra of 5' -GMP, guanosine, inosine and products of their reactions with 1, 2,3, and 4 were also recorded. On the whole, full-scan ESI-MS spectra of the pure nucleobases revealed the presence of cationic and anionic species that are highly reflective of both their solution ionic composition and their propensity t9 form polymeric clusters. Analyses of mass spectra acquired from their reaction solutions with the aforementioned platinum complexes indicated very slow kinetics. However, all complexes investigated formed, to various degrees, Pt-nucleobase adducts with guanosine and inosine, but not with 5'-GMP. The products included species having coordination numbers of III, IV, V, and VI, among which the first-time· observed, coordinatively saturated, jive-coordinate PtlI-nucleobase complexes were of most interest. The latter complexes are presumably stabilized by 7tback- donation involving the filled d orbitals of the PtII centre and the empty pz· orbital of MeCN. All products, whose peaks appeared inlull-scan ESI-MS spectra, are believed to represent solution species rather than artifacts of gas-phase processes. Finally, negativeion ESI-MSn spectra recorded in reaction solutions of 1 and 4 with guanosine and of the latter complex with inosine revealed the negative-ion-ESI-MS first-time observed, noncovalent, nucleoside-chloride adducts, with the source of chloride anion being complexes 1 and 4 theillselves. In contrast, no such adducts were observed to form with Na25'-GMP or its protonated fonn. Few suggestions are offered for the possible cause(s) behind the absence of such adduct ions.

The Effects of Magnetic Dilution and Applied Pressure on Several Frustrated Spinels

The effects of magnetic dilution and applied pressure on frustrated spinels GeNi2O4, GeCo2O4, and NiAl2O4 are reported. Dilution was achieved by substitution of Mg2+ in place of magnetically active Co2+ and Ni2+ ions. Large values of the percolation thresholds were found in GeNi(2-x)MgxO4. Specifically, pc1 = 0.74 and pc2 = 0.65 in the sub-networks associated with the triangular and kagome planes, respectively. This anomalous behaviour may be explained by the kagome and triangular planes behaving as coupled networks, also know as a network of networks. In simulations of coupled lattices that form a network of networks, similar anomalous percolation threshold values have been found. In addition, at dilution levels above x=0.30, there is a T^2 dependency in the magnetic heat capacity which may indicate two dimensional spin glass behaviour. Applied pressures in the range of 0 GPa to 1.2 GPa yield a slight decrease in ordering temperature for both the kagome and triangular planes. In GeCo(2-x)MgxO4, the long range magnetic order is more robust with a percolation threshold of pc=0.448. Similar to diluted nickel germanate, at low temperatures, a T^2 magnetic heat capacity contribution is present which indicates a shift from a 3D ordered state to a 2D spin glass state in the presence of increased dilution. Dynamic magnetic susceptibility data indicate a change from canonical spin glass to a cluster glass behaviour. In addition, there is a non-linear increase in ordering temperature with applied pressure in the range P = 0 to 1.0 GPa. A spin glass ground state was observed in Ni(1-x)MgxAl2O4 for (x=0 to 0.375). Analysis of dynamic magnetic susceptibility data yield a characteristic time of tau* = 1.0x10^(-13) s, which is indicative of canonical spin glass behaviour. This is further corroborated by the linear behaviour of the magnetic specific heat contribution. However, the increasing frequency dependence of the freezing temperature suggests a trend towards spin cluster glass formation.

A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite

A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite: Chitin synthase, the enzyme responsible for the synthesis of chitin in fungal cell wall was extracted from young hyphae of Choanephora cucurbitarum and Phascolomyces articulosus, susceptible and resistant hosts, respectively, to the mycoparasite, Piptocephalis virginiana. Crude enzyme was identified and characterized by measuring the incorporation of the substrate [14C]-UDP-N-acetylglucosamine, into chitin. Most activity occurred in mixed membrane fraction. Inhibition of activity with Polyoxin D and activation with proteases, N-acetyl-glucosamine and magnesium and other ions was observed. Properties of the crude enzyme preparation such as cofactor requirement, Vmax , apparent Km value for UDP-GlcNAc, inhibition by Polyoxin D, response to pH and to temperature, and stability at 4°C were determined. Enzyme activity from both fungi displayed basically the same features as the corresponding enzymes reported from other mucoraceous fungi. However, the two preparations from P. articulosus and C. cucurbitarum differed from each other in their expressed activity (i.e., the preparations from ~ articulosus exhibited higher latency and higher specific chitin synthase activity than the corresponding preparations from ~ cucurbitarum). Trypsin was effective in activation only over a narrow concentration range. Acid protease was the most effec.tive activator. En.dogenous protease estimation indicated higher protease activity in C. cucurbitarum than in P. articulosus. The suggestion is made that regulation of chitin synthase activities may be related to host resistance in the mycoparasitic system.

A mass spectrometric study of some pesticides /|nK. S. Subramanian. -- 260 St. Catharines, Ont. : [s. n.],

The fragmentation processes in the mass spectra of a series of organophosphorus, organochlorine, thio and dithiocarbamate as well as a number of miscellaneous pesticides have been studied i n detail by using the Bendix timeof- flight, MS-12 single-focussing and MS-30 double-focussing mass spectrometers. Interpretation of all the spectra have been presented; their mode s of dissociation elucidated, aided by metastable transitions wherever possible and the structures of the various f ragmentation species postulated wherever f easible. The fragmentation mechanisms are based on the concepts of inductive, resonance and steric ef~ects. Multiple bond cleavages accompanied by simultaneous bond formation and rearrangement reactions involving cycli c t r ansition states have clarified t he formation of various ions . Due emphasis has been placed on the effect of the functional groups or substituents in altering the mass spectral behaviour of the pesticides as they form the basis for the identifi cation of the otherwise identical pesticides. The organophosphorus pesticides which have been studied include i) the phosphates (eg: DDVP and Phosdrin ); ii) phosphorothionates (eg: Parathion, 0-2, 4 dichloro phenyl 0, O-diethyl thionophosphate); iii) phosphorothioites (eg: Tributyl phosphorotrithioite); i V) phosphorothioates (eg: Ethion) and v) phosphorodithioates (eg: Carbophenolthion). Cleavages and rearrangements of the ester moiety dominate the spectrum of phosdrin while that of DDVP is + dominated by t he fragmentation modes of the (OH30)2P=0 + moiety. Fragmentation §f the (CH30)2P=S characterises the spectrum of (OH30)2"P -Cl while cleavages of the + (C2H50 )2P=S species mark the spectra of parathion and 0-2, 4- di chlorophenyl O, O-diethyl thiophosphate. The 0(, cl eavages of the thioether f unction rather than + cleavages of the (C2H50)2P=S signify the spectrum of carbophenolthion. Tributyl phosphorotrithioite behaves more like an aliphatic hydrocarbon than like the corresponding phosphites. The isopropyl and butyl esters of 2, 4 dichlorophenoxy acetic acid show cleavage and rearrangement ions typical of an ester. In spite of its structural similari ty to pp' - DDT and pp' - DDD, Kalthane has a completely different mass spectral behaviour due to the influence of its hydroxyl function. The thiocarbamate pesticides studied include Eptam and Perbulate. Both are structurally similar but having different alkyl substituents on nitrogen and sulphur. This structurQlsimilarity leads to similar types of (N-C), (O-S) and (S-alkyl cleavages). However, perbulate differs from Eptam in showing a rearrangement ion at mle 161 and in forming an isocyanate ion as the base peak. In Eptam the base peak i s the alkyl ion. The dithiocarbamate, Vegadex, resembles the thiocarbamates in undergoing simple cleavages but it differs from them in having a weak parent ion; in the formation of its base peak and in undergoing a series of rearrangement reactions. The miscellaneous pesticides studied include 1-Naphthalene acetic aCid- methyl ester, Fiperonyl butoxide and Allethrin. The ester i s stable to electron impact and shows only fewer ions. Piper onyl butoxide, a polyether, shows characteristics of an et her, alcohol and aldehyde . Allethrin is regarded as an ester of the type R-C-O-R1 with n R being a substituted cyclopr opane moiety and o Rt, a substituted cyclopentenone mOiety. Accordingly it shows cleavage ions typical of an aliphatic ester and undergoes bond ruptures of the cyclic moieties to give unusual ions. Its base peak is an odd electron ion, quite contrary to expectations.

An experimental investigation of dechanneling in copper single crystals

This investigation comprises a comparison of experimental and theoretical dechanneling of MeV protons in copper single crystals. Dechanneling results when an ion's transverse energy increases to the value where the ion can undergo small impact parameter collisions with individual atoms. Depth dependent dechanneling rates were determined as functions of lattice temperature, ion beam energy and crystal axis orientation. Ion beam energies were IMeV and 2MeV,temperatures ranged from 35 K to 280 K and the experiment was carried out along both the (lOa) and <110) axes. Experimental data took the form of aligned and random Rutherford backscattered energy spectra. Dechanneling rates were extracted from these spectra using a single scattering theory that took explicit account of the different stopping powers experienced by channeled and dechanneled ions and also included a correction factor to take into account multiple scattering effects along the ion's trajectory. The assumption of statistical equilibrium and small angle scattering of the channeled ions allows a description of dechanneling in terms of the solution of a diffusion like equation which contains a so called diffusion function. The diffusion function is shown to be related to the increase in average transverse energy. Theoretical treatments of increase in average transverse energy due to collisions of projectiles with channel electrons and thermal perturbations in the lattice potential are reviewed. Using the diffusion equation and the electron density in the channel centre as a fitting parameter dechanneling rates are extracted. Excellent agreement between theory and experiment has been demonstrated. Electron densities determined in the fitting procedure appear to be realistic. The surface parameters show themselves to be good indicators of the quality of the crystal.

Mass spectral studies of some pentafluorophenyl derivatives of group V /|nby Andrew Tanner Rake. -- 260 St. Catharines, Ont. : [s. n.],

The mass spectra of compounds of t he series (C6F5 )3-n MP~ (n = 1,2,3, M = P and As ), (C6F5>3Sb, Ph) Sb and (C6F5 )2SbPh have been studied in detail and the important modes of fragmentation were e1ucidated, a ided by metastable ions. Various trends attributed to the central atom and or the . substituent groups have been noted and, where applicable, compared to recent studies on related phenyl and pentafluorophenyl compounds of groups IV and V. The mass spectra of fluorine containing organometallic compounds exhibit characteristic migrations of fluorine to t he central atom, giving an increasing abundance of MF+, MF2+' and RMF+ (R = Ph or C6F5) ions on descending the group_ The mass spectra of pentafluorophenyl , antimony, and arsenic compounds show a greater fragmentation of the aromatic ring than those of phosphorus. The mixed phenyl pentafluorophenyl derivatives show a characteristic pattern depending on the number of phenyl grm.lps present but show t he general characteristics of both the tris(phenyl) and tris(pentafluorophenyl) compounds. The diphenyl pentafluorophenyl der ivatives show the loss of biphenyl ion as the most import ant step, the los s of phenyl t o give the i on PhMC6F5 + being of secondary importance. The ,bis(pentafluorophenyl) phenyl derivatives fragment primarily by loss of PhC6F5 to give C6F5M+ ions, the abundance of t hese increasing r apidly from phosphorus to arsenic. This species then, exhibits a characteristic fragmentation observed in the tris(penta- fluorophenyl ) compounds. However, the abundance of (C6F5)2M+ species in these compounds i s small. I ons of the type C6H4MC6F4 + and tetrafluorobiphenylene ions C6H4C6F4 + also are observed on substitution of a phenyl group for a penta- fluorophenyl group. The fully fluorinated species (C6F4)2M+ is not observed, although octafluorobiphenylene ions , (C6F4)2+' are evident in several spectra . The appearance potentials of the major ions were obtatned from the ionisation efficiency curves. Attempts were made to correlate these to the effect of the central atom in substituent groups, but the large errors involved prevented the reaching of quantitative conclusions, although it would appear that the electron is removed from the ligand in the ionisation of t he parent molecule .

Molecular Magnetism: The Design, Synthesis, and Characterization of New Building Blocks for Molecule-based Magnetic Materials

Two classes of building blocks have been prepared and characterized and their coordination chemistry explored working towards the preparation of new molecule-based magnetic materials. In the first project, the amine functionality of 3,3'-diamino-2,2'- bipyridine was exploited for the preparation of a new family of ligands (H2L 1)-(H2L 4). The molecular structures of three ligands have been fully characterized by X-ray crystallography. [molecular structure diagram will not copy here, but is available in full pdf.] The coordination chemistry of these ligands with divalent first row transition metal ions was investigated. For ligand (H2L1), the molecular structures of four coordination complexes with stoichiometries [Zn2(Ll)(OAc)(MeO)]2 (I), [Cu2(L1)(OAc)2 (II), [Li(L1)]3 (III), and [Ni(L1)]3 (IV) were determined by X-ray crystallography. For ligand (H2L2), a Cu(II) complex of stoichiometry [Cu3(L2)(OAc)3MeO] (V) was determined by X-ray crystallography. The magnetic properties of complexes (II), (III), and (V) have been fully elucidated. In project two, synthetic strategies for the preparation of porphyrin molecules bearing triol substituents is presented. Following this approach, three new porphyrin derivatives have been prepared and characterized [Zn(HPTPP-CH2C(CH20H)3)] (VI), [P(TPP)(OCH2C(CH2)H)3)2]+CL- (VII), and [P(OEP)(C6H5)(OCH2C(CH2OH)3)]+Cl- (VIII). Attempts to exchange the labile methoxide bridges of a tetraironIIl single molecule magnet of stoichiometry [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane) with the triol appended porphyrins will be discussed. [molecular structure diagram will not copy here, but is available in full pdf.]