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Natural bond orbital (NBO) analysis obtained from density functional theory (DFT) calculations was used to show whether syndetic donation (π or σ-electron density in the vicinity of the agostic carbon interacting with a metal center) is present in a variety of ligand-directed aromatic ring C–H bond activations by palladium acetate. Benzyl alcohol gave a complex with reduced agostic donation compared to N,N-dimethylbenzylamine and 2-phenylpyridine and similar syndetic π-donation except for 2-phenylpyridine, which is much lower. Phenethyl alcohol gave a simple coordination complex without interactions and 3-phenylpropan-1-ol gave an agostic interaction with a benzylic C–H bond and no syndetic donation. The ketones 1-tetralone, 1-indanone, and acetophenone gave agostic complexes with well-developed syndetic π-donation; PhCO2H gave well-developed agostic and syndetic π-donation, PhCH2CO2H gave an η2-complex, and PhCH2CH2CO2H gave a coordination complex with no interactions. Amide functional groups next to an ...

Natural bond orbital (NBO) analysis obtained from density functional theory (DFT) calculations on the intermediates and transition states in the ambiphilic metal–ligand activation/concerted metalation deprotonation (AMLA/CMD) mechanism for the cyclopalladation reaction of N,N-dimethylbenzylamine with palladium acetate shows the agostic, syndetic (π or σ-electron density from the ring that assists the agostic donation), and backbonding orbital overlaps involved. The analysis shows that these components are absent for the anagostic intermediate but progressively increase in going from the anagostic/agostic transition state to the agostic intermediate and then to the agostic/cyclopalladate transition state. For the all-important agostic/cyclopalladate transition state, agostic donation is very large [NBO E(2) total, 152.3 kcal mol–1], the syndetic π-donations total over half of this at 106.3 kcal mol–1 with the overlap forming in close proximity to the carbon where palladation occurs, and there is the emerge...

Structural, spectroscopic, QTAIM and NBO analysis results obtained from disperson-corrected density functional theory (DFT-D) calculations on the agostic intermediate [PdCl2(1-tetralone oxime)] (1) show that both agostic C Hσ and syndetic C Cπ donations are effected by electronic substituents on the aromatic ring. Changing the C5-substituent in 1 to σ-electron withdrawing SO2Cl unexpectidly increases both the agostic and π-donations; π-electron withdrawing N2PO(OEt)2 increases the agostic donation but the π-donation is replaced by C8 to Pd covalency; σ-electron donating B(OH)3− gives similar agostic donation to H but the syndetic π-donation increases markedly; π-electron donating S− reduces the agostic donation almost to zero and the syndetic π-donation turns to Pd to C8 covalency. For (N) OMe ligand [PdCl2(1-tetralone imine)] agostic complex (7), σ-electron withdrawing SO2Cl at C5 shows similar agostic and π-donations to the (N) OH analogue; π-electron withdrawing N2PO(OEt)2 changes 7 to an anagostic complex; σ-electron donating B(OH)3− produces less syndetic π-donation than in the (N) OH analogue and π-electron donating S− reduces the agostic donation much less than the (N) OH analogue but retains the Pd C8 covalency arising from carbon based orbitals. For the σ and π-electron withdrawing N N+ BF4− substituent, Pd C8 covalency arises from metal based orbitals.

DFT-D calculations show that the above-plane M····H-C separations in square-planar complexes of palladium (II) and Rh(I) containing the iso-quinoline ligand are influenced by whether the complexes are neutral, anionic or cationic due mainly to changes in atomic charge on the metal, H and C atoms but the nature of the cis-ligands also plays a part because of the development of weak intramolecular interactions. The Pd····H-C separations are effected by strong σ-withdrawing or π-donating substituents placed at C7 of the iso-quinoline ligand with the shortest anagostic Pd····H separation of 2.218 A achieved using the π-donating S- substituent in an anionic complex. The same substituent on the cationic complex leads to Pd-C covalency. Lack of flexibility of the iso-quinoline ring system prevents the anagostic carbon approaching the metal when the electrostatics are favourable. Instead of an anagostic/preagostic divide it is suggested that all complexes with above plane Pd····H-C close approaches are termed anagostic and where some agostic covalency develops below an NBO E(2) value of 5 kcal mol-1 they be regarded as having an emerging preagostic condition.

Density functional theory (DFT) calculations on the effect of steric size adjacent to an agostic interaction in ligand assisted Pd–C bond formation involving aromatic rings gives insight into why the synthetic reaction can fail as the size of an alkyl group is increased. In [PdCl2(1-tetralone oxime)] agostic complexes, changing the C(7)-substituent on the ligand through the series H, Me, CHMe2, and CMe3 progressively reduces agostic and syndetic donations. For (N)–CMe3 imine complexes, CMe3 steric pressure at C(7) switches off agostic donation and increases syndetic donation significantly, especially where the aromatic ring can rotate. Electron withdrawal from the aromatic ring in this type of system has little effect, but electron donation into the ring invokes η1-covalency, especially with strong π-donation. This covalency can be switched off by further π-donation and the syndetic donation restored. These steric effects can be expected to impact the success of C–C bond formation chemistry derived from P...

Although many Confederation biographies were written before the gender turn, even recent studies often neglect gender as a category of analysis. This neglect implies that thinking about gender would, at best, add to the story of Confederation but could not change it. It also leaves men's experience of gender unexamined, perpetuating the idea that men's monopoly over politics in this era was simply a fact – perhaps regrettable, but indisputable, and therefore unworthy of study. This article considers how dividing political (men's) history and gender (women's) history into separate domains has affected how biographers have written about Confederation. It also proposes that critical feminist biography can help historians re-entangle politics and gender and, thereby, re-evaluate what was at stake in the Confederation negotiations and on what bases support for this ongoing political project was won, lost, regained, and reconfigured.

Structures and properties were obtained by density functional calculations for the complexes [RhCl(CO)2(L)] (L = isoquinoline ligands) containing close Rh····H separations. Electrostatic repulsion keeps the atoms apart and Rh····C separations are prevented from developing much further by ligand inflexibility. Natural bond orbital analysis shows small components of C–Hσ to Rh (agostic) donation and Rh to C–Hσ* backdonation. Both σ- and π-electron-withdrawing substituents produce an increase in the Rh····H separation, while ligand inflexibility prevents σ- and π-electron-donating substituents from decreasing the Rh····C separation. Substitution at C2 by Me closes up the Rh····H separation and CHMe2 and CMe3 groups cause a structural change which minimises the interaction. Substitution at C2 by a Ph group gives the shortest Rh····H separation (2.187 A) and largest Rh to C–Hσ* backdonation. Electron donation at C7 or at C7 and C9 increases the Rh····H separation, as the ligand flexes substantially to accommodate a decrease in the Rh····C separation. On the basis of the minimal C–Hσ to Rh (agostic) donation involved, the complexes are best described as preagostic.

The presence of 14 intramolecular interactions relevant to bond rotational flexibility in coordination compounds important in the context of crystal engineering were identified by density functional theory calculations in the crystal structure of the highly crystalline oxoimido complex [Mo(NC6H4CMe3-2)(O)Cl2(bipy)] (1). A combination of computational techniques including noncovalent interaction index properties and Quantum Theory of Atoms analysis which are based on the computed electron density as well as natural bond orbitals analysis, were used to uncover the nature of the interactions. Weakly stabilizing intramolecular interactions involving electrostatic contributions were found for O····HC, N····HC, and CH····HC, close separations involving the bipy ligand where coordination does not allow flexibility and for O····HC, N····HC, Cl····HC, CH····HC, and C····HC close contacts where C–N and C–C rotations of the imido ligand would allow flexibility. Partial covalency is not a significant feature of these...

Using depictions of ‘Miss Canada’ in editorial cartoons and political campaign posters published in English Canada between 1867 and 1914 as a case study, this article argues that the repetitive deployment of feminised and eroticised images of the nation summoned particular gender, sexual and political identities into being and entangled viewers’ psychic investments in masculine, heterosexual and nationalist subjectivities. It also considers how Miss Canada's normative representation as white conflated racial whiteness and Canadian-ness, and how images hailed viewers into racial subjectivities that were leashed to national identity. Rather than querying how or why the woman-as-nation trope elicited nationalist sentiment in an already-constituted subject, this analysis examines how imagery provoked viewers’ identification with subject positions that were co-constituted with nationalism. Impassioned and even violent nationalism becomes more comprehensible when we consider that the woman-as-nation was capable of producing attachments to national identity that, for some, were inseparable from and tantamount to psychic investments in gender, sexual and racial identities. While Canadian scholars have recognised that Miss Canada was a significant popular culture icon during the long nineteenth century and acknowledged this icon's embeddedness in gender, sexual and national discourses, studies have tended to describe Miss Canada's role in consolidating hegemonic ideologies and power relations and underestimate visual culture's constitutive capacities. The extent of Miss Canada's hetero-erotic coding has also largely escaped historians’ notice. Although a few scholars have explored visual culture's role in Canadian national identity formation during this era, this study makes a unique contribution by foregrounding the productive work of popular imagery in co-constituting and entwining national and sexual subjectivities.

Breast tall cell carcinoma with reversed polarity (TCCRP) is rare and previously referred to as solid papillary carcinoma with reverse polarity. This low grade tumor commonly exhibits IDH2 p.Arg172 mutation, however is not completely understood at the molecular level. We present a case of TCCRP in a 55 year old woman with a 0.7 cm left breast mass. A core biopsy was performed with immunohistochemistry. Lumpectomy and sentinel lymph node biopsy were completed two months later. MammaPrint$^{\textregistered}$ and BluePrint$^{\textregistered}$ gene expression profilers were performed on an excision block. Microscopically, the tumor was composed of circumscribed nests of columnar cells, with focal papillary architecture. Tumor cells had apically located nuclei with grooves and rare inclusions. Tumor cells were positive for CK5, IDH1/2, and calretinin, and myoepithelial cells were absent. BluePrint$^{\textregistered}$ subtyped the tumor as basaloid. MammaPrint$^{\textregistered}$ classified the tumor as high risk for metastasis. TCCRP presents a diagnostic challenge. Although these rare breast carcinomas are generally reported to have an indolent clinical course, molecular analysis by gene expression profiling classified this tumor as high risk of recurrence with a basaloid type. Therefore, molecular analysis of this tumor may lead to conflicting data regarding prognosis and treatment considerations. Clinicians and patients should weigh published data and individual prognostic information for treatment planning. Our patient and clinical team opted for radiation without chemotherapy. More cases of TCCRP need to be studied to better understand its molecular profile.

Rapidly emerging technologies that capture, manage, communicate, and use information in digital form are dramatically transforming the way that farming and agribusiness are done across the globe—especially for large commercial farms. Nowhere is this more true than in the Russian Federation, where many large agri-holding companies operate at the cutting edge of the application of digital technologies. These large industrial farms, with sizable land and livestock holdings, possess the financial resources and the management know-how to own and leverage the most advanced technology. Some have sophisticated information technology staff to develop and manage digital approaches to many aspects of farm operations. However, many of Russia’s farms—especially small and medium farms—lack the connectivity and skillsets needed to take advantage of such technologies. Many of these small farms also lack the equipment and the know-how to take advantage of the transformational digital opportunities from which they might profit. Yet the ever-expanding connectivity and availability of information and communication technology and digital tools could make it possible for transformational developments to happen on small, traditional, remote, and disadvantaged farms too.

Structures and properties for the complexes [RhCl(CO)2(L)] (L = 1-tetralone oximes and imines) containing anagostic C–H separations were obtained from density functional calculations using the dispersion corrected PBE-D3 functional. Bench-top syntheses were carried out for several complexes to obtain NMR spectral comparisons. The calculations show a ligand (N)–OH group positions the anagostic hydrogen (H8) more over the metal and (N)–OCMe3 and (N)–CMe3 groups more out towards the chloro ligand where weak H···Cl bonding is involved. This positioning is a result of varying Rh–N bond lengths and steric factors arising below the coordination plane where methyl-group H atoms can form additional anagostic approaches to the metal and weak hydrogen bonds with the chloro ligand. QTAIM analysis indicates weak electrostatic repulsion for the Rh···H8 approaches. Disparity between the metal and C–H bond orbital energies precludes covalency. Both σ and π-withdrawing substituents para to C8 increase the H8 positive charge lengthening the Rh···H8 separation; σ and π-donating substituents decrease the charge and shorten the separation. For (N)–OH ligands, the C7-alkyl groups Me, CHMe2 and CMe3 do not affect the lengths of the Rh···H8 separations by a steric effect and no significant electronic effects are observed for C7-NO2, OMe or F substituents. A combination of an (N)-CMe3 group and electron-donating groups at C5 and C7 of the aromatic ring do not effect the Rh···H8 separation but the Rh···C8 separation decreases significantly leading to a C-anagostic interaction. For all the complexes the ligand adapts to accommodate the anagostic approaches.

During the 1870s and 1880s, when cartoonists working for Britain’s most popular satirical magazine, Punch , wanted to represent Canada visually, they drew on centuries’ old artistic conventions that depicted America, and, later, British North America, as a woman and an “Indian.” During the same period, in Canada’s most popular satirical magazine, Grip , normative portrayals of the embodied nation were unambiguously white. The visual trope of an indigenized, feminized body was enlisted instead to represent Manitoba and the North-West Territories. This imagery disavowed British depictions of Canada as a racialized and colonized subject and relocated the identity of the colonial Other onto the Prairie West. In other words, Grip ’s images constituted a representational politics that involved both “looking back” at Empire and directing the imperial gaze onto others. Resume: Dans les annees 1870 et 1880, quand les caricaturistes travaillant pour Punch , le magazine satirique le plus populaire de Grande-Bretagne, voulaient representer visuellement le Canada, ils s’inspiraient de conventions artistiques seculaires, lesquelles depeignaient l’Amerique et, par la suite, l’Amerique du Nord britannique, sous les traits d’une femme et d’une « Indienne ». A la meme epoque, dans Grip , le magazine satirique le plus populaire du Canada, la norme consistait a representer la nation sous les traits d’une Blanche, sans equivoque. C’est plutot pour representer le Manitoba et les Territoires du Nord-Ouest que l’on avait recours a l’indigenisation de concert avec la feminisation du corps. Cette imagerie desavouait les representations britanniques du Canada comme un sujet racialise et colonise, et deplacait l’identite de l’Autre colonial vers les plaines de l’Ouest. Autrement dit, les images de Grip constituaient une politique de la representation qui impliquait a la fois un regard sur l’Empire et la projection du regard imperial sur d’autres.

A 500 MHz NMR study of the reaction between 1-tetralone oxime and PdCl42−in CD3OD shows resonances attributable to a potential agostic intermediate prior to the formation of the insoluble cyclopalladated product which itself was characterised by X-ray crystallography. Calculated structural, spectroscopic, QTAIM, NBO and NCI analysis results obtained from density functional theory (DFT) calculations give a full description of the putative agostic intermediate [PdCl2(1-tetralone oxime)] (1) which is shown to include a previously unrecognised π-electron density donation from the aromatic ring to the metal in close proximity to the agostic carbon atom. Changing the (N)–OH donor to (N)–OMe does not effect the magnitude of these interactions. (N)–OH and (N)–OMe acetophenone imines in which the aromatic ring has the potential to rotate show similar agostic and π-electron donation to the alicyclic ring counterparts. 1-Tetralone which coordinates to the metal by a Pd–O bond that is much weaker than the Pd–N complexes has a slightly stronger agostic component and slightly weaker π-electron donation than the oxime counterpart.

Density functional theory (DFT) calculations reveal that for ligand directed aromatic ring C–H bond activation, the agostic donation can share the same antibonding acceptor orbitals as a previously unrecognised π-donation from the aromatic ring of the ligand. The recognition of carbon based orbitals assisting the agostic interaction has significant implication for C–H bond activation chemistry.

We report a combined experimental and computational study of the first bis(imido) and tris(imido) complexes of a group 4 metal. Reaction of [Ti(NAr)(NHAr) 2(py) 2] (1, Ar = 2,6-C 6H 3iPr 2) with 3 equivs. of MeLi gave the lithium-stabilised tris(imide) [TiMe(NAr) 3{Li(py)} 3] (2). Reaction of 1 with 2 equivs. of MeLi in the presence of ArNH 2 gave the corresponding bis(imide) [Ti(NAr) 2(NHAr) 2{Li(py)} 2] (3). All three compounds 1, 2 and 3 have substantial Ti-N imide multiple bond character. Orbital and Mayer bond order analysis show that the formal bond orders are best viewed as ca. 3, 2.5 and 2, respectively, with a further attenuating effect on the multiple bonding by the [Li(py)] + ion coordination. Compounds 2 and 3 are the first examples of any group 4 metal simultaneously containing two or three multiply-bonded ligands. © 2012 The Royal Society of Chemistry.

Polymeric {TiO(salen)}n prepared from [Ti(OCHMe2)2(acac)2] and salen-H2 in MeOH and with an apparent chain structure, is mostly insoluble but dissolves when strongly heated in aromatic aldehydes or ketones, depositing the insoluble form again on cooling. p-Tolualdehyde performed differently, giving a red solution from which insoluble red crystals were deposited. X-ray crystallography showed the complex was [{Ti(salen)(O2CC6H4Me-4)-O-Ti(salen)(O2CC6H4Me-4)]. Solvent (1) (solvent = p-tolualdehyde or p-toluic acid) containing a Ti–O–Ti bridge. Reaction of {TiO(salen)}n with p-tert-butylbenzoic acid in the presence of excess p-tolualdehyde gave [{Ti(salen)(O2CC6H4CMe3-4)-O-Ti(salen)(O2CC6H4CMe3-4) ]. 4-CH3C6H4CHO (2) for which an X-ray crystal structure determination indicated similar connectivity around the metal as for (1). {TiO(salen)}n heated strongly in isobutyrophenone (PhCOCHMe2) also gave red crystals which X-ray analysis showed structural similarity to (1) and (2) but incorporating a PhCO2-ligand. {TiO(salen)}n heated in acetophenone gave a product which X-ray analysis showed was a dioxo-bridged dimer (4) in which C–C bond formation had occurred on one side of each salen ligand.

X-ray photoelectron spectra of {[WCl4(NPh)]2}, WCl4(O) and the η2-acetylene complex {[WCl4(η2-PhC2Ph)]2}show W 4f7/2 binding energies (35.8, 37.0 and 35.1 eV, respectively) which are consistent with a formal oxidation state of W(vi). [WCl2(NPh)(NCMe3)(bipy)] and [WCl2(O)(CHC{CH3}3)(PMe3)2] (binding energies 34.2 and 34.1 eV) are also W(vi). The imido complexes [WCl3(NPh)(PMe3)2], {WCl3[NC6H3( Pr 2 i )-2,6](PMe3)2}, {WCl3[NC6H3( Pr 2 i )-2,6](dmbipy)} and the η2-acetylene complexes [WCl3(η2-PhC2Ph)(PMe3)2] and [WCl3(η2-PhC2Ph)(PMe2Ph)2] have binding energies in the range 33.6–34.2 eV consistent with tungsten (v). Imido complexes [WCl2(NPh)(PMe3)3],[BPh4][WCl(NPh)(MeCN)(PMe3)2], [WCl2(NPh)(L)(PMe3)3] (L = Me2CCH2, PhC2Ph), {WCl2[NC6H3(Pri)2-2,6](PhC2H)(PMe3)2], {WCl2[NC6H3(Pri)2-2,6](PhC2Ph)(dmbipy)] and [WCl2(NCMe3)(PhC2Ph)(bipy)] have binding energies in the range 32.5–34.0 eV consistent with W(iv). The η2-nitrile complex [WCl2(η2-NCC6H4Me-4)(PMe3)3] (binding energy 32.9 eV) is also W(iv). The range of binding energies for the complexes [WCl4(P)2] (P = PMe3, PMe2Ph and PEt3) and [WCl4(PMe3)3] which are more obviously W(iv) is 33.5–34.4 eV. The η2-acetylene complexes [WCl2(η2-PhC2Ph)(L)(PMe3)2] (L = PMe3, CH2CH2 and CO) and [WCl2(η2-PhC2Ph)(CO)(PMe2Ph)2] have binding energies (range 32.7–33.8 eV) consistent with W(iv). The range of W 4f7/2 binding energies for these complexes confirms that the electron withdrawing properties of ligands are more important in determining core electron level energies than structural considerations.

The results of an ab initio study on a family of hydroxy peroxy radical–water complexes formed from the oxidation of E-2-hexenal, which constitutes an important component of biogenic atmospheric emissions, are reported. Binding energies for the β-hydroxy-γ-peroxy hexanal (β- and γ-positions are relative to the carbonyl) radical–water complex and the γ-hydroxy-β-peroxy hexanal radical–water complex are predicted to be to 3.8 and 3.6 kcal/mol, respectively, computed at the MP2/6-311++G(2d,2p)//B3LYP/6-311++G(2d,2p) computational level. Natural bond orbital reveals that conventional hydrogen bonding between the water and the hydroxy and aldehyde functional groups of the radical are primarily responsible for the stability of the complex. It can be shown that the peroxy moiety contributes very little to the stability of the radical–water complexes. Thermochemistry calculations reveal estimated equilibrium constants that are comparable to those recently reported for several hydroxy isoprene radical–water complexes. The results of this report suggest that the hexanal peroxy radical–water complexes are expected to play a significant role in the complex chemistry of the atmosphere. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Reaction of PhCONH2 with [WCl6] under reflux in benzene gives a near quantitative yield of [WOCl4(NCPh)] (1) which can be prepared directly by the reaction of PhCN and [WOCl4]. PhCONH2 reacts with [WOCl4] under reflux in benzene to give [WO2Cl2(NCPh)] (2) and with [NbCl5] under similar conditions to give [NbOCl3(NCPh)] (3). PhCONH2 and TiCl4 give [TiCl4(NH2COPh)2] (4). Reaction of the aroyl isocyanate PhCONCO with [WOCl4] gave [WOCl4(NCPh)] (1) and 4-Me3CPhCONCO and [WOCl4] gave [WOCl4(NCPhCMe3-4)] (5). PhCONCO reacts catalytically with [WOCl4] or [WOCl4(NCPh)] to give quantitative yields of PhCN. Similarly, 4-Me3CPhCONCO and 2-ClCPhCONCO react catalytically with [WOCl4] to give complete conversion to 4-Me3CPhCN and 2-ClCPhCN. DFT studies show structures and intermediates in support of a possible catalytic mechanism. This involves initial complexation followed by formation of a metallocycle from the W O bond and the C N bond of the isocyanate. Rearrangement and elimination of CO2 leads to an amidate complex that undergoes C–O bond scission and O migration to the W atom to give PhCN bound to the WOCl4 moiety in a cis arrangement. This complex is unstable with respect to dissociation which completes the catalytic cycle. The overall reaction WOCl4 + PhC(O)NCO → WOCl4·PhCN + CO2 is exothermic (ΔH = −20.7 kJ mol−1) and is favoured from free energy considerations (ΔG = −69.3 kJ mol−1).

Reaction of diamine-bis(phenol) ligands containing a mixture of N-methyl and N,N′-dimethyl-N,N-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine, H2L1 and H2L3, with [Ti(OCHMe2)4 in absolute ethanol under reflux without exclusion of air and moisture gives [(L1)Ti (OEt–O–Ti(OEt)(L1)] (1). [(L3)Ti(OEt)–O–Ti(OEt)(L3)] (2) forms when the remaining solution containing [(L3)Ti(OEt)2] (3) (characterised by X-ray crystallography) is hydrolysed with H2O. For the N-methyl and N,N′-dimethyl ligand mixture H2L2 and H2L4, which contain tert-butyl groups on the ortho-positions of the aryl rings, [(L2)Ti(OEt)–O–Ti(OEt)(L2)] (4) forms much more slowly and [(L4)Ti(OEt)2] (5) does not hydrolyse when H2O is added. When the N-protonated ligand N,N-bis(2-hydroxy-3-methyl-5-tert-butylbenzyl)ethylenediamine, H2L5, is used, rapid hydrolysis to two isomers of [(L5)Ti(OEt–O–Ti(OEt)(L5)] (6) occurs without addition of water. For N,N-bis(2-hydroxy-3,5-di-tert-butylbenzyl)ethylenediamine, H2L6, hydrolysis to [(L6)Ti(OEt)–O–Ti(OEt)(L6)] (7) occurs slowly when H2O is added. For pendant NMe2 ligand N,N-dimethyl-N′,N′-bis(2-hydroxy-3-methyl-5-tert-butylbenzyl)ethylenediamine, H2L7, the hydrolysis reaction readily gives [(L7)Ti(OEt)–O–Ti(OEt)(L7)] (8) for which an X-ray crystal structure was obtained. The ortho-tert-butyl ligand derivative H2L8 formed a complex analysing as [(L8)Ti(OEt)–O–Ti(OEt)(L8)] (9) which could not be studied further due to insolubility. Pendant pyridine ligand N-(2-pyridylmethyl)-N,N-bis(2′-hydroxy-3′-methyl-5′-tert-butylbenzyl)amine, H2L9, apparently forms isomers of [(L9)Ti(OEt)–O–Ti(OEt)(L9)] and possibly [{(L9)Ti(O)}2] from [(L9)Ti(OEt)2] (10). The ortho-tert-butyl ligand derivative H2L10 formed [(L10)Ti(OEt)–O–Ti(OEt)(L10)] (11) for which an X-ray crystal structure was obtained.

The chloro-tris-phenoxo complexes [TiCl(OAr)3] (OAr = OC6H4CMe3-4 (1), OC6H3Me2-2,4 (2), OC6H2Me3-2,4,6 (4), OC6H3(CHMe2)2-2,6 (5), OC6H3(CMe3)2-2,4 (6) and OC6H4Ph-2 (8) are prepared by heating 3 equivalents of the phenol and [TiCl4] in toluene. X-ray crystal structure determinations show that 2 is a phenoxy-bridged dimer with the ortho-methyl groups making the beginning of a pocket about the terminal chloro ligand and 6 is a tetrahedral monomer in which the pocket is more well developed by the ortho-tert-butyl groups. Both 2 and 6 react with dmbipy to give [TiCl(OAr)3(dmbipy)] [OAr = OC6H3Me2-2,4 (3) and OC6H3(CMe3)2-2,4 (7)] in which the original pocket is destroyed. Reaction of TiCl4 with 3 equivalents of LiOC6H4Ph-2 in diethyl ether gives [TiCl(OC6H4Ph-2)3(diethyl ether)] (9) for which an X-ray crystal structure determination shows a trigonal bipyramidal coordination geometry with the diethyl ether lying trans to the chloro ligand. The three phenoxide ligands make up the equatorial plane which takes the 2-phenyl substituent on each phenoxo ligand away from the chloro ligand resulting in a partially collapsed cavity. The tied-back analogues of 2 and 6, [TiCl{(OC6H2Me2-2,4-CH2-6)3N}] (11) and [TiCl({OC6H2(CMe3)2-2,4-CH2-6}3N)] · diethyl ether (12), are prepared by adding (HOArCH2)3N [Ar = C6H2Me2-2,4 and C6H2(CMe3)2 2,4] to [TiCl(OCHMe2)3] in diethyl ether. An X-ray crystal structure of 12 showed a trigonal bipyramidal structure with a coordination environment about the terminal chloro ligand similar to that found in 6. Complex 12 reacts with pyridine to form the 6-coordinate complex [TiCl({OC6H2(CMe3)2-2,4-CH2-6}3N)(py)] (13).

Reaction of [CpTiCl3] with 1 equiv. of Me3SiOC6H4CMe3-4 in benzene or thermalisation with an excess of neat Me3SiOC6H4CMe3-4 gives good yields of crystalline [CpTiCl2(OC6H4CMe3-4)] (1) for which an X-ray crystal structure determination shows a distorted tetrahedral geometry. Reaction of [CpTiCl3] and Me3SiOC6H3CMe3-2-Me-4 via the benzene solvent method or the direct thermalisation gives rise to crystalline [CpTiCl2(OC6H3CMe3-2-Me-4)] (2) for which an X-ray crystal structure determination shows a distorted tetrahedral geometry little changed from complex 1 but with the phenoxide ligand ring rotated so that two of the tert-butyl group methyls straddle one chloro ligand. Refluxing [CpTiCl3] and Me3SiOC6H4Ph-4 in toluene gave crystalline [CpTiCl2(OC6H4Ph-2)] (3) which X-ray crystallography shows has a distorted tetrahedral geometry little changed from 1 or 2. The phenoxide ligand ring is rotated less in 1 than in 2 or 3 with the 2-phenyl substituent sited between the chloro and Cp ligands. The complexes differ only in the interplanar angle between the Cp and phenoxide ligand phenyl rings [6.4(1)° for 1, 29.4(1)° for 2 and 22.2(1)° for 3]. DFT calculations carried out on 2 are in good agreement with the X-ray crystal structure. A relaxed PES scan shows that the tert-butyl group in the complex cannot freely rotate past the adjacent chloro ligand and is essentially locked in close proximity to it. There is a shallow minimum (2 kJ/mol within a range of 60 degrees) for the Ti–O–C–C dihedral angle indicating there is sufficient torsional motion within the molecule to accommodate the tert-butyl group in the observed position.

Thermalisation of TiCl 4 and two equivalents of a phenol in toluene is found to be the best preparative method for quantitative yields of a variety of dichlorobis(phenoxo) complexes. [TiCl 2 (OC 6 H 4 CMe 3 -4) 2 ] (1) is monomeric in benzene, a phenoxo-bridged dimer in the solid state and undergoes coordination expansion with 4,4'-dimethyl-2,2'-bipyridine (dmbipy) to give [TiCl 2 (OC 6 H 4 CMe 3 -4) 2 (dmbipy)] (2). Also monomeric are [TiCl 2 (OC 6 H 2 Me 3 -2,4,6) 2 ] (3) and [TiCl 2 (O-C 6 H 3 iPr 2 -2,6) 2 ] (5) which expand their coordination with dmbipy to give [TiCl 2 (OC 6 H 2 Me 3 -2,4,6) 2 (dmbipy)] (4) and [TiCl 2 (OC 6 H 3 iPr 2 -2,6) 2 (dmbipy)] (6). In contrast [TiCl 2 (OC 6 H 2 {CMe 3 } 2 -2,6-Me-4) 2 ] (7) is only partially formed by the thermolysis reaction and does not coordinatively expand with dmbipy. [TiCl 2 (OC 6 H 3 Me 2 -2,4) 2 ] (8) is monomeric in benzene and reacts to form [TiCl 2 (OC 6 H 3 Me 2 -2,4) 2 -(dmbipy)] (9). [TiCl 2 (OC 6 H 3 {CMe 3 } 2 -2,4)2] (10) forms along with the tri-phenoxo complex [TiCl{OC 6 H 3 (CMe 3 ) 2 -2,4} 3 ]. [TiCl 2 (OC 6 H 3 CMe 3 -2-Me-6) 2 ] (11) is monomeric in benzene and forms [TiCl 2 (OC 6 H 3 CMe 3 -2-Me-6) 2 (dmbipy)] (12). 2-Phenylphenol and 1-napthol form [TiCl 2 (OC 6 H 4 Ph-2) 2 ] (13) and [TiCl 2 (OC 1 0 H 9 ) 2 ] (14) which are monomeric in benzene. DFT calculations give structural parameters for monomeric [TiCl 2 (OC 6 H 5 ) 2 ] (15) in good agreement with the X-ray data for [TiCl 2 (OC 6 H 3 Me 2 -2,6) 2 ]. Each oxygen of the phenoxo ligand in 15 acts essentially as a 2π donor to titanium and there is substantial p π (O)-p π *(C=C) backbonding with the phenyl ring, which is absent in [TiCl 2 (OCH 3 ) 2 ] (16). The global minimum for the dimer [(TiCl 2 (OC 6 H 5 ){μ-OC 6 H 5 }) 2 ] is in almost perfect agreement with the crystal structure obtained for [(TiCl 2 (OC 6 H 5 }{μ-OC 6 H 5 }) 2 ] or [(TiCl2(OC6H4CMe3-4}{μ-OC 6 H 4 CMe 3 -4}) 2 ] (1). The dimerisation energy for 15 is -26.2 kJ.mol - 1 .

To achieve the high adaptive optics sky coverage necessary to allow the GMT Integral-Field Spectrograph to access key scientific targets, the on-instrument adaptive-optics wavefront-sensing system must patrol the full 180 arcsecond diameter guide field passed to the instrument. Starlight must be held stationary on the wavefront sensor (accounting for flexure, differential refraction and non-sidereal tracking rates) to ~ 1 milliarcsecond to provide the stable position reference signal for deep AO observations and avoid introducing image blur. Hence a tight tolerance of 1/180,000 is placed on the positioning and encoding accuracy for the cryogenic On-Instrument Wave-Front Sensor feed. GMTIFS will achieve this requirement using a beam-steering mirror system as an optical relay for starlight from across the accessible guide field. The system avoids hysteresis and backlash by eliminating friction and avoiding gearing while maintaining high setting speed and accuracy with a precision feedback loop. Here we present the design of the relay system and the technical solution deployed to meet the challenging specifications for drive rate, accuracy and positional encoding of the beam-steering system.

Many microelectromechanical systems (MEMS) require a mechanism that amplifies motion. This article investigates the use of the pseudorigid body model (PRBM) to design fully compliant micro-half-pantographs for this purpose. The results demonstrate the ability to amplify motion with a compliant mechanism with no assembly or pin joints. The PRBM was used to develop equations for input-output displacement, force-deflection, and maximum nominal stress-deflection predictions. Predictions compared favorably to finite-element and experimental results. This work emphasizes further that the traditional method of trial-and-error design can be substituted by the pseudorigid body model approach. *Communicated by B. Gilmore.

Two models that address the emplacement rate of the upper plate of the Heart Mountain Detachment (HMD) have been advanced. These are the catastrophic tectonic denudation model and the slow, incremental continuous allochthon model. We compared the two models by analyzing upper and lower plate rocks for a detachment-related overprint of the older, layer-parallel Laramide–Sevier calcite twinning strain fabric. Lower plate Pilgrim Limestone samples, even those collected a few meters below the detachment, show no evidence of a detachment-related twinning strain overprint (negative expected values, NEVs, avg. 8.3%) of the Laramide–Sevier layer-parallel fabric. The allochthonous upper plate carbonate rocks preserve the layer-parallel Laramide–Sevier shortening strain, but the shortening axis (e1) for each block occurs in different, non-EW and both subhorizontal and non-subhorizontal orientations. For the six upper plate blocks that preserve chaotic shortening axis orientations, no evidence of any detachment-related twinning strain overprint (NEVs avg. 7.5%) was found. In the absence of any HMD-related twinning overprint, the upper plate allochthon motion must have been rapid enough to be accommodated by fracturing of upper plate rocks without additionally twinning any calcite. We conclude that the emplacement of the upper plate of the HMD was not accompanied by an overprint of the Laramide–Sevier twinning fabric and that models that require catastrophic, rather than slow, incremental emplacement rates are best supported by these data.

Thermalisation of TiCl4 and phenol (1∶1) in toluene gave [TiCl3(OC6H5)] 1. The more soluble complex [TiCl3(OC6H4CMe3-4)] 2 is monomeric in benzene and reacts with 4,4′-dimethyl-2,2′-bipyridyl (dmbipy) to give mer-[TiCl3(OC6H4CMe3-4)(dmbipy)] 3 and the disproportionation product [TiCl2(OC6H4CMe3-4)2(dmbipy)]. The complex [TiCl3(OC6H2Me3-2,4,6)] 4 is monomeric in benzene whereas [TiCl3(OC6H3Pri2-2,6)] 5 partially disproportionates in solution into [TiCl2(OC6H3Pri2-2,6)2] and reacts with dmbipy to give mer-[TiCl3(OC6H3Pri2-2,6)(dmbipy)] 6 and [TiCl2(OC6H3Pri2-2,6)2(dmbipy)]. Thermalisation of 2,6-di-tert-butyl-4-methylphenol and TiCl4 in toluene caused debutylation but [TiCl3{OC6H2(CMe3)2-2,6-Me-4}] 7 forms in light petroleum (bp range 40–60 °C). Complex 7 is monomeric in benzene and does not form adducts with dmbipy or other sigma donors. A crystal structure determination of 7 showed a monomer with distorted tetrahedral co-ordination, a Ti–O bond length of 1.750(2) A and Ti–Cl bonds longer than in TiCl4 but shorter than in [TiCl3(C5H5)] or [TiCl3{C5H3(CMe3)2-1,3}]. 2,4,6-Tri-tert-butylphenol debutylates when thermalised with TiCl4 in toluene giving [TiCl3{OC6H4(CMe3)2-2,4} ] 8. The complexes [TiCl3{OC6H2(CMe3)2-2,6-OMe-4}] 9, [TiCl3(OC6H3CMe3-2-Me-4)] 10, [TiCl3(OC6H4Ph-2)] 11 and the 1-naphthoxide complex [TiCl3(OC10H7)] 12 were also prepared. Density functional calculations performed on the models 4 and [TiCl3(OMe)] showed both lone pairs on oxygen donate electron density to titanium but O(2p)-to-CC (π*) donation weakens the Ti–O interaction in the phenoxide complex; Cl(2p)-to-Ti(3d) donation is much reduced in the methoxide complex. The system [TiCl3(OC6H4CMe3-4)]/AlMe3 is 280 times more active than [TiCl3Cp] (Cp = cyclopentadienyl)/AlMe3 for low pressure (6 psi) ethylene polymerisation but 1//3 less active than TiCl4/AlMe3.

Imido exchange of [TaCl3(NCMe3)(py)2] with 2-tert-butylaniline in refluxing benzene and crystallisation of the product from CH2Cl2 gave the anionic complex [Hpy][TaCl4(C6H4CMe3-2)(py)] 1. X-Ray structural analysis shows that with the Ta–N–C bond angle at 165.1(5)° two of the tert-butyl substituent methyl groups sit above two meridional chloro ligands but NMR spectroscopy indicates that the tert-butyl group can still rotate in solution. Reaction of isocyanates ArNCO [Ar = C10H7 (naphthyl), C6H4CMe3-2 or C6H4Ph-2] with WOCl4 in refluxing benzene gave [{WCl4(NC10H7)}x] 2, [{WCl4(NC6H4CMe3-2)}x] 3, and [{WCl4(NC6H4Ph-2)}x] 4 which NMR spectra show convert from two species into one in CDCl3. In refluxing toluene, 2-tert-butylphenyl isocyanate also forms the metallacyclic amido complex [WCl4{NHC6H4(CMe2CH2)-2(C,N)}] 5. The d1 complexes [WCl3(NC10H7)(PMe3)2] 6, [WCl3(NC6H4CMe3-2)(PMe3)2] 7, [WCl3(NC6H4Ph-2)(PMe3)2] 8, [WCl3(NC10H7)(PMe2Ph)2] 9 and [WCl3(NC10H7)(PMePh2)2] 10 were prepared, and show hindered imido ligand aryl C–N bond rotation. A crystal structure determination of 6 shows the naphthyl ring C-8 proton positioned between a chloro and phosphine ligand. Also prepared to demonstrate hindered aryl C–N bond rotation were the d2 complexes [WCl2(NC10H7)(PMe3)3] 11, [WCl2(NC6H4CMe3-2)(PMe3)3] 12, [WCl2(NC6H4Ph-2)(PMe3)3] 13 and [WCl2(NC10H7)(PMe2Ph)3] 14. Crystal stucture determinations show the tert-butyl group in 12 located above a chloro ligand and the phenyl group in 13 located between a chloro and phosphine ligand. They also show the methyl and isopropyl substituents in [MoCl2(NC6H3Me-2-Pri-6)2(dme)] 15 form an anti configuration and in [MoCl2(NC6H4CMe3-2)2(dme)] 16 a syn configuration is identified where the Mo–N–C bond angles are determined by steric effects and crystal packing forces.

Cuticular hydrocarbon profiles of individual workers of the ant Formica truncorum were measured and found to contain relatively few hydrocarbons. Pentacosane, heptacosane, nonacosane and hentriacontane dominated the mixture, but small amounts of the corresponding alkenes were also present. Principal component analysis and nested analysis of variance showed that workers from different colonies varied significantly in quantitative aspects of their cuticular hydrocarbon profiles. Furthermore, differences between habitat-patches within populations and (to some extent) between populations were also detected. Finally, workers from the same colony, sampled only a few months apart, were found to be different in the quantitative composition of their cuticular hydrocarbon profiles, emphasising the importance of collecting samples from a colony at a single point in time.

Addition of Me3SiNHCMe3 to the 4-electron donor alkyne complex [{WCl4(PhC2Ph)}2] gave [{WCl2(NCMe3)(PhC2Ph)(NH2CMe3)}x] 1 for which the acetylenic carbon resonance position, δ 156.23, in the 13C-{1H} NMR spectrum indicated a 2-electron donor alkyne. Small changes in δ for derivatives [NEt4][WCl3(NCMe3)(PhC2Ph)(NH2CMe3)] 2 (161.28), trans-dichloro complexes [WCl2(NCMe3)(PhC2Ph)(bipy)] 3 (bipy = 2,2′-bipyridyl, δ 163.60) and [WCl2(NCMe3)(PhC2Ph)(dmbipy)] 4 (dmbipy = 4, 4′-dimethyl-2,2′-bipyridyl, δ 162.93) as well as cis-dichloro complexes [WCl2(NCMe3)(PhC2Ph)(py)2] 5 (py = pyridine, δ 155.78), [WCl2(NCMe3)(PhC2Ph)(PMe3)2] 6 (δ 151.15) and [WCl2(NCMe3)(PhC2Ph)(PMe2Ph)2] 7 (δ 153.37) indicate small electronic differences in the alkyne–metal bonding. A crystal structure determination of 6 showed trans-phosphines, cis-chloro ligands and a cis arrangement of a 4-electron donor imido ligand [W–N 1.763(6) A] and a 2-electron donor alkyne [W–C 2.131(6) and 2.111(7) A]. The compound Me3SiNHCHMe2 added to [{WCl4(PhC2Ph)}2] followed by dmbipy gave [WCl2(NCHMe2)(PhC2Ph)(dmbipy)] 8 (δ 163.16), Me3SiNHCH2Me and dmbipy formed cis- and trans-dichloro complexes [WCl2(NCH2Me)(PhC2Ph)(dmbipy)] 9 (δ 152.76 and 159.03) and 10 (δ 163.31) respectively. A crystal structure of determination 10 showed W–C bond lengths [2.085(8) A] somewhat shorter than in 6, consistent with the increase in alkyne π⊥ donation for 10 indicated by δ. The compound Me3SiNHC6H3Pri2-2,6 and [{WCl4(PhC2Ph)}2] gave [{WCl2(NC6H3Pri2-2,6)(PhC2Ph)(NH2C6H3Pri2-2,6)}x] 11 (δ 166.51) which with dmbipy gave cis-dichloro [WCl2(NC6H3Pri2-2,6)(PhC2Ph)(dmbipy)] 12 (δ 167.50). Other complexes prepared were [WCl2(NC6H3Me2-2,6)(PhC2Ph)(dmbipy)] 13 (δ 167.26), [WCl2(NC6H3Pri2-2,6)(PhC2Ph)(py)2] 14 (δ 158.78) and [WCl2(NC6H3Pri2-2,6)(PhC2Ph)(PMe3)2] 15 (δ 154.40). The compound Me3SiNHC6H3Pri2 –2,6 and [NEt4][WCl5(PhC2Ph)] gave [NEt4][WCl4(NHC6H3Pri2-2,6)(PhC2Ph)] 16 where δ (167.40) indicates an amido ligand allows conversion of the alkyne into a 2-electron donor.

The complexes [WOCl3(OAr)]x(Ar = 4-tert-butylphenyl 1, 2,6-dimethylphenyl 2, 2,6-di-iso-propylphenyl 3) are prepared by reacting HOAr with an excess of [WOCl4] but are thermodynamically unstable forming bis-phenoxide complexes on standing. Debutylation occurs with 2,6-di-tert-butylphenol but a monophenoxide 4 was prepared with the lithium phenoxide. The complex debutylates and forms bisphenoxides on standing. An X-ray crystal structure of 2 shows a dimeric chloro-bridged structure with terminal oxo and 2,6-dimethylphenoxide ligands. The oxo ligand acts essentially as a 1 σ, 1π donor to tungsten [WO(1) bond length 1.679(4) A] and the phenoxide as a 1σ, 1π donor [WO(2) bond length 1.820(4) A]. The phenyl ring positions to reduce interactions of the methyl substituents with the oxo and chloro ligands but NMR spectra show rapid phenoxide rotation in solution. Variable temperature NMR spectral studies of 4 show the tert-butyl groups lock the rotation which may be important in the debutylation process. The complexes have limited catalytic potential due to instability.

Reaction of benzonitrile with WCl 6 in the presence of CCl 2 CCl 2 gave the complex [{WCl 4 (NCPh)} x ] of undetermined structure which does not show equivalent chemistry to the d 0 complexes [{WCl 4 (PhC 2 Ph)} 2 ] and [{WCl 4 (NPh)} 2 ]. The complex [WCl 2 (η 2 -NCC 6 H 4 Me-4) (PMe 3 ) 3 ] 1 can be prepared by reduction of [WCl 4 (PMe 3 ) 3 ] with 2 equivalents of Na/Hg amalgam in the presence of p-toluonitrile. The nitrile carbon in the 13 C-{ 1 H} NMR spectrum appears at δ 232.2 consistent with a four-electron donor nitrile ligand. Reaction of [WCl 2 (NC 6 H 3 Pr i 2 - 2,6)(PMe 3 ) 3 ] with purified p-toluonitrile in refluxing toluene or reduction of [WCl 3 (NC 6 H 3 Pr i 2 - 2,6)(PMe 3 ) 2 ] in benzene with 1 equivalent of Na/Hg amalgam in the presence of p-toluonitrile led to [WCl 2 (NC 6 H 3 Pr i 2 - 2,6)(η 2 -NCC 6 H 4 Me-4)(PMe 3 ) 2 ] 2 as shown by 1 H, 13 C-{ 1 H} and 31 P-{ 1 H} NMR spectroscopy. The position of the nitrile carbon in the 13 C-{ 1 H} NMR spectrum (δ 178.9) is consistent with a two-electron donor nitrile ligand. Reaction of [WCl 2 (NC 6 H 3 Pr i 2 - 2,6)(PMe 3 ) 3 ] with unpurified p-toluonitrile gave [WCl 2 (NC 6 H 3 Pr i 2 - 2,6)(NCOC 6 H 4 Me-4)(OPMe 3 )(PMe 3 )] 3 in addition to 2. A crystal structure determination showed cis orientated imido and acylimido ligands [W–N 1.769(5) and 1.823(6) A, W–N–C 174.5(5) and 158.9(5)°], cis-chloro ligands and a cis orientation of the PMe 3 and OPMe 3 ligands. The bond lengths and angles about the NCOPh function are not significantly different to those of a variety of uncomplexed organic amide groups. Hartree–Fock and density-functional calculations performed on the model complex [WCl 2 (NMe)(NCOH)(OPH 3 )(PH 3 )] 4 showed structural parameters in good agreement with those of 3 when the phenyl groups were removed. An NBO (natural bond orbital) analysis of the W–NMe bond generated one σ and two π bonds between nitrogen s and p atomic orbitals (AOs) and tungsten d AOs. The nitrogen of the NCOH ligand binds to tungsten via one σ and one π bond. In contrast to the NMe ligand, the NBO analysis located a nitrogen ‘lone pair’ orbital on the NCOH ligand which overlaps somewhat with the C–O π orbitals (11% for carbon, 5% for oxygen) and with tungsten (8%). The structural and theoretical studies indicate the NMe ligand nitrogen atom dominates the π donation.

The title adduct, [TiCl2(C23H30O2)(C13H10O]·0.5C13H10·C4H10O, is a monomer with a trigonal–bypyramidal coordination sphere of the TiIVatom in which the ligand O atoms of the bidentate diphenolate anion are located in both apical and equatorial positions. Chloride ligands occupy the remaining two equatorial sites of the trigonal bypyramid with the fluoren-9-ol O atom occupying the other apical site. The hydroxy group H atom of this latter group is hydrogen bonded to an O atom of a non-coordinating diethyl ether molecule. The title compound also contains a further fluorene solvent molecule, which lies across a centre of symmetry and which is equally disordered over an inversion centre.