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The synthesis and characterisation (IR, NMR, HR-MS, and X-ray crystallography) of six oxazoline Zn complexes, containing enolate ligands derived from a series of (Z)-1-R-2-(4',4'-dimethyl-2'-oxazolin-2'-yl)-efh-1-en-1-ols (R=[C.sub.6][H.sub.5], [C.sub.6][H.sub.4]-p-N[O.sub.2], [C.sub.6][H.sub.4]-p-O[CH.sub.3], [CF.sub.3], [CH.sub.3], or [CMe.sub.3]) is detailed. All derivatives are air-stable solids of formula Zn[([L.sup.n]).sub.2] and are formed in the presence of the title ligands and [NEt.sub.3]. Reasonable yields (53%-82%) are obtained with the exception of R= [CMe.sub.3] (9%); in this case, by-product formation and high solubility affected complex isolation. Crystallographic characterisation reveals that in all cases the ligands are bound in a [kappa].sup.2]-N, O-bonding motif. Little structural diversity is noted within the series; these complexes are further placed into structural context with related Zn materials containing oxazoline, phenolate, and (or) Schiff base ligands. Key words: oxazoline, coordination complexes, zinc, enolate, X-ray crystal structure, Introduction The naturally occurring Group 12 elements hold a unique position within coordination chemistry due to the overwhelming predominance of the +2 oxidation state. This is, of course, a result [...]

A method for the synthesis of substituted 1,2,4,5-oxadiazaboroles is described, in which hydroxylamines, nitriles, and diarylborinic acids engage in a three-component condensation reaction. The protocol provides access to a substitution pattern that is not readily available through other methods--namely, 2,3-disubstitution, with a tetracoordinate boron center. Structures of representative members of this class of heterocycles were determined by single crystal X-ray diffraction analysis. Key words: boron, condensation, heterocycles, nitriles, Introduction Boron-based heterocycles are of interest from several perspectives, (1) including fundamental studies of structure, bonding, reactivity, and photophysical properties, along with potential applications in material science, (2) catalysis, (3) [...]

The synthesis and characterization of a new paramagnetic ligand, 4-(N′-methyl-2′-benzimidazolyl)-1,2,3,5-dithiadiazolyl (MebimDTDA), is presented. MebimDTDA exhibits polymorphism in the solid state. The red microcrystalline form (Form I-red) is diamagnetic below T = 370 K, consistent with typical multi-center two-electron bonding interactions (i.e., pancake bonds) between planar π-radicals. By contrast, the green–black crystalline form (Form II-green) exhibits paramagnetic properties consistent with the observed unusual crystal packing in which some, but not all, of the radicals are arranged in a typical pancake-bonded geometry. Crystallographic analysis, magnetic data, and computational methods are employed to elucidate the structure-property relationship, with an emphasis on the role of crystal packing. [ABSTRACT FROM AUTHOR]

Air‐stable palladium(II) and copper(I) complexes containing the 4,4′,6,6′‐tetramethoxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine) ligands, (R)‐Ph‐Garphos ((R)‐L1) and ((S)‐Ph‐Garphos ((S)‐L1), were synthesized and characterized by 1H‐, 13C‐, and 31P{1H} NMR spectroscopy and elemental analyses. The PdCl2((R)‐Ph‐Garphos) ((R)‐1) and PdCl2((S)‐Ph‐Garphos) ((S)‐1) complexes were assessed for the Suzuki‐Miyaura cross‐coupling of aryl halides with phenylboronic acid under ambient conditions, or naphthyl substrates under reflux. X‐ray crystal structures of the copper complexes revealed that [Cu((R)‐Ph‐Garphos)I] ((R)‐2) crystallized as a three‐coordinate monomer in the orthorhombic space group P212121 whereas [Cu((S)‐Ph‐Garphos)I] ((S)‐2) crystallized as a tetrahedral (μ‐I) dimer in the same crystal system. The synthesis of the analogous [Cu((R)‐Ph‐Garphos)OAc] ((R)‐3) is also described. Complexes (R)‐2 and (R)‐3 were evaluated for the asymmetric hydrosilylation of ketones wherein enantioselectivities of up to 83 % ee were achieved. [ABSTRACT FROM AUTHOR]

The crystal structures of 16 boron subphthalocyanines (BsubPcs) with structurally diverse axial groups were analyzed and compared to elucidate the impact of the axial group on the intermolecular π–π interactions, axial‐group interactions, axial bond length and BsubPc bowl depth. π–π interactions between the isoindole units of adjacent BsubPc molecules most often involve concave–concave packing, whereas axial‐group interactions with adjacent BsubPc molecules tend to favour the convex side of the BsubPc bowl. Furthermore, axial groups that contain O and/or F atoms tend to have significant hydrogen‐bonding interactions, while axial groups containing arene site(s) can participate in π–π interactions with the BsubPc bowl, both of which can strongly influence the crystal packing. Bulky axial groups did tend to disrupt the π–π interactions and/or axial‐group interactions, preventing some of the close packing that is seen in BsubPcs with less bulky axial groups. The atomic radius of the heteroatom bonded to boron directly influences the axial bond length, whereas the axial group has minimal impact on the BsubPc bowl depth. Finally, the crystal growth method did not generally appear to have a significant impact on the solid‐state arrangement, with the exception of water occasionally being incorporated into crystal structures when hygroscopic solvents were used. These insights can help with the design and fine‐tuning of the solid‐state structures of BsubPcs as they continue to be developed as functional materials in organic electronics. [ABSTRACT FROM AUTHOR]

The 2-adamantyl (2-Ad) group is a particularly challenging alkyl to install on a transition metal, with the only reported 2-Ad complexes of platinum being those of Pt(II). The question of whether 2-Ad complexes with platinum in the oxidation state +IV can be made and whether they are stable is answered here. The Pt(IV) compound trans-[(bpy)[PtMe.sub.2](2-Ad)I] (bpy = 2,2=-bipyridine) was synthesized via oxidative addition of iodomethane to [(COD)PtMe(2-Ad)] (COD = 1,5-cyclooctadiene) in the presence of bpy. Iodide abstraction with silver triflate (triflate anion, [OTf.sup.-] = [CF.sub.3][SO.sub.3.sup.-]) produced trans-[(bpy)[PtMe.sub.2](2-Ad)(OTf)]. Both complexes were unambiguously characterizedby1DNMR ([.sup.1]H,[.sup.13]C) spectroscopy and X-ray crystallography. Both show evidence for the large steric bulk of the 2-Ad group (through the conformation of the complex adopted) and also for its exceptionally pronounced transinfluence (very long bonds to iodide/triflate trans to adamantyl). Both of the new platinum(IV) adamantyl complexes were extremely stable, even to prolonged heating. Key words: platinum(IV), oxidative addition, adamantane, density functional calculations, trans influence. Le groupe 2-adamantyle (2-Ad) est un group alkyle particulierement difficile a lier a un metal de transition; les seuls exemples connus de complexes de 2-Ad avec le platine sont ceux de Pt(II). Nous abordons dans le present article la question a savoir si les complexes de 2-Ade avec le platine a l'etat d'oxydation +IV peuvent etre fabriques et s'ils sont stables. Nous avons synthetise le complexe de Pt(IV) trans-[(bpy)[PtMe.sub.2](2-Ad)I] (bpy = 2,2=-bipyridine) par addition oxydante de l'iodomethane au [(COD)PtMe(2-Ad)] (COD = 1,5-cyclooctadiene) en presence de bpy. L'abstraction de l'atome d'iode par le triflate d'argent (anion triflate, [OTf.sup.-] = [CF.sub.3][SO.sub.3.sup.-]) a produit le trans-[(bpy)[PtMe.sub.2](2-Ad)(OTf)]. Nous avons caracterise sans equivoque les deux complexes par spectroscopie RMN 1D ([.sup.1]H, [.sup.13]C) et radiocristallographie. Les deux methodes revelent un fort encombrement sterique du groupe 2-Ad (par la conformation qu'adopte le complexe) et egalement une influence trans exceptionnellement marquee (liaisons tres longues entre l'iode ou le triflate et le groupe adamantyle). Les deux nouveaux complexes d'adamantylplatine(IV) etaient extremement stables, meme lorsqu'ils etaient exposes a une chaleur prolongee. [Traduit par la Redaction] Mots-cles : platine(IV), addition oxydante, adamantane, calculs de la fonctionnelle de la densite, influence trans., Introduction The chemistry of platinum alkyls has been a testbed for new organometallic chemistry for over 110 years now. When Pope and Peachey synthesized trimethylplatinum(IV) iodide in 1909, it was [...]

Select triphenyl stannanes bearing either a formally sp2 or sp3 hybridized amine, viz 2-(pyC2H4)SnPh3 (2: py = pyridinyl), 4-(pyC2H4)SnPh3 (3), 2-(pzC2H4)SnPh3 (4: pz = pyrazyl), and Me2N(CH2)3SnPh3 (6), were prepared and characterized by NMR spectroscopy (119Sn, 13C, 1H), and additionally, in the case of 2, by single crystal X-ray diffraction. Bromination of 2 to yield 2-(pyC2H4)SnPhBr2 (8) was achieved in good yield. X-ray crystallographic analysis of 8 revealed two unique molecules with 5-coordinate Sn centers featuring Sn-N distances of 2.382 (5) and 2.363 (5) Å, respectively. The calculated structures of the non- and hypercoordinating C,N-stannanes (1–9) were in good agreement with available crystallographic data. The relative stabilities of hyper- and non-hypercoordinating conformers obtained from conformational sampling were determined by comparison with reference conformers and by natural bond orbital (NBO) energetic analyses. Reduction of 8 to the dihydride species, 2-(pyC2H4)SnPhH2 (9), and subsequent conversion to the polystannane, -[2-(pyC2H4)SnPh]n- (15), by transition metal-catalyzed dehydropolymerization was also achieved. Evidence for the decomposition of 15 into a redistributed distannoxane, {2-(pyC2H4)SnPh2}2O (16), was also observed. [ABSTRACT FROM AUTHOR]

Polar crystalline materials, a subset of the non‐centrosymmetric materials, are highly sought after. Their symmetry properties make them pyroelectric and also piezoelectric and capable of second‐harmonic generation (SHG). For SHG and piezoelectric applications, metal oxides are commonly used. The advantages of oxides are durability and hardness – downsides are the need for high‐temperature synthesis/processing and often the need to include toxic metals. Organic polar crystals, on the other hand, can avoid toxic metals and can be amenable to solution‐state processing. While the vast majority of polar organic molecules crystallize in non‐polar space groups, we found that both 7‐chloro‐1,3,5‐triazaadamantane, for short Cl‐TAA, and also the related Br‐TAA (but not I‐TAA) form polar crystals in the space group R3m, easily obtained from dichloromethane solution. Measurements confirm piezoelectric and SHG properties for Cl‐TAA and Br‐TAA. When the two species are crystallized together, solid solutions form, suggesting that properties of future materials can be tuned continuously. [ABSTRACT FROM AUTHOR]

Poly(3‐hexylthiophene) (P3HT) is a well‐studied conjugated polymer; however, the end‐group functionalization of these polymers is limited by fundamental synthetic challenges. Generally, end‐capping agents are used to terminate the Kumada catalyst transfer polycondensation (KCTP) to install functional end‐groups at the propagating chain end. In this work, it is shown that P3HT can be prepared with a novel SNAr‐active external initiator, followed by end capping to afford heterobifunctional end‐groups that exhibit orthogonal chemical reactivity. This orthogonal chemistry can be leveraged in sequential "click"‐type reactions to ultimately achieve the synthesis of triblock copolymers. More specifically, it is shown that the synthesis of a new pentafluorophenyl initiator allows one to append this readily functionalized group at the initiating end during P3HT synthesis. After reaching the desired degree of polymerization, an ethynyl group is incorporated at the polymer terminus using an end‐capping Grignard reagent. Critically, this heterobifunctional P3HT allows for both orthogonal para‐fluoro thiol reactions, a subset of nucleophilic aromatic substitution (SNAr), and copper‐catalyzed alkyne‐azide cycloadditions (CuAAC). The efficacy of this heterobifunctional polymer design is demonstrated by assessing sequential "click" reactions with different nonconjugated polymer blocks to either end of the P3HT polymer block. [ABSTRACT FROM AUTHOR]