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Studies of the supramolecular chemistry of iso‐tellurazole N‐oxides have been confined to non‐polar media until now. To overcome that limitation, an iso‐tellurazole N‐oxide was derivatized with a primary alcohol group; the compound is soluble in polar solvents and stable in acidic to neutral aqueous media. Nickel (II) and iron (II) form macrocyclic complexes with six molecules of that iso‐tellurazole N‐oxide in a hitherto not‐observed macrocyclic arrangement defined by CTe⋅⋅⋅O chalcogen bonds and κ6‐O bound to the metal ion. This behaviour is in sharp contrast with the κn‐Te (n=1,2,4) complexes formed by soft metal ions. [ABSTRACT FROM AUTHOR]

A new synthesis that avoids the use of Me2PH is reported for (Me2PCH2BMe2)2, and this method was extended to the synthesis of (Ph2PCH2BMe2)2. The ligand precursor (Me2PCH2BMe2)2 did not react with [{M(μ-Cl)(cod)}2] (cod = 1,5-cyclooctadiene; M = Ir and Rh) or [PtCl2(cod)] at room temperature. However, after 12–48 hours at 65–70 °C, these reactions afforded (a) [Ir(cod)(μ-Cl)(Me2PCH2BMe2)] (1), (b) an equilibrium mixture of (Me2PCH2BMe2)2, [{Rh(μ-Cl)(cod)}2] and [Rh(cod)(μ-Cl)(Me2PCH2BMe2)] (2), and (c) cis-[Pt(μ-Cl)2(Me2PCH2BMe2)2] (3), respectively. By contrast, reactions between the phenyl-substituted analogue, (Ph2PCH2BMe2)2, and [{M(μ-Cl)(cod)}2] (cod = 1,5-cyclooctadiene; M = Ir and Rh) proceeded over the course of 1 hour at 20 °C to generate [M(cod)(μ-Cl)(Ph2PCH2BMe2)] (M = Ir (4) and Rh (5)), indicative of room temperature (Ph2PCH2BMe2)2 dissociation. Room temperature reactions of (Ph2PCH2BMe2)2 with [{Rh(μ-Cl)(coe)2}2] (coe = cyclooctene) using a 1 : 1 or 3 : 1 stoichiometry also afforded [{Rh(coe)(μ-Cl)(Ph2PCH2BMe2)}2] (6) or [RhCl(Ph2PCH2BMe2)3] (7), respectively, where the latter is a borane-appended analogue of Wilkinson's catalyst, and reactions of (Ph2PCH2BMe2)2 with [PtX2(cod)] (X = Cl or Me) yielded cis-[Pt(μ-Cl)2(Ph2PCH2BMe2)2] (8) and cis-[PtMe2(Ph2PCH2BMe2)2] (9). Compounds 1–9, (Me2PCH2BMe2)2 and (Ph2PCH2BMe2)2 were crystallographically characterized. In compounds 1–5 and 8, each chloride co-ligand is coordinated by the borane of an R2PCH2BMe2 ligand. Additionally, in the solid state structure of 6, each bridging chloride ligand interacts weakly with a pendent borane, and in 7, the chloride ligand is tightly coordinated to the borane of one Ph2PCH2BMe2 ligand and weakly coordinated to the borane of a second Ph2PCH2BMe2 ligand. By contrast, both boranes in 9 (and one of the three boranes in 7) are non-coordinated. [ABSTRACT FROM AUTHOR]

Reactions of the ethylene hydride complex trans-[(dmpe)2MnH(C2H4)] (1) with secondary hydrogermanes H2GeR2 at 55–60 °C afforded the base-free terminal germylene hydride complexes trans-[(dmpe)2MnH(＝GeR2)] (R = Ph; 2a, R = Et; 2b). Room temperature reactions of 2a or 2b with an excess of the primary hydrogermanes H3GeR′ (R′ = Ph or nBu) afforded trans-[(dmpe)2MnH(＝GeHR′)] (R′ = Ph; 3a, R′ = nBu; 3b) in rapid equilibrium with small amounts of 2a/b, as well as the digermyl hydride complex mer-[(dmpe)2MnH(GeH2R′)2] {R′ = Ph (4a) or nBu (4b)} and the trans-hydrogermane germyl complex trans-[(dmpe)2Mn(GeH2R′)(HGeH2R′)] {R′ = Ph (5a) or nBu (5b)}. Pure 3b was isolated from the reaction of 2b with H3GenBu, whereas 3a decomposed readily in solution in the absence of free H3GePh, and a pure bulk sample was not obtained. Reactions of 1 with H3GeR′ (R′ = Ph or nBu) also proceeded at 55–60 °C to afford mixtures of 3a/b, 4a/b and 5a/b, accompanied by remaining 1. However, upon continued heating to consume 1, various unidentified manganese-containing intermediates were formed, ultimately affording the germanide complex [{(dmpe)2MnH}2(μ-Ge)] (6) in 17–49% spectroscopic yield. Pure trans,trans-6 was isolated in 27% yield from the reaction of 1 with H3GenBu, and it is notable that this reaction involves stripping of all four substituents from the hydrogermane. Complexes 2a, 3a, and 6 were crystallographically characterized, and the nature of the Mn＝Ge bonding in these species (as well as in 2b and 3b) was probed computationally. [ABSTRACT FROM AUTHOR]

Iso-tellurazole N-oxides are promising supramolecular building blocks. While in neutral solutions, they form tetra-and hexameric macrocyclic aggregates linked by Te ... O secondary bonding (t hole interactions or chalcogen bonds), protonation of the oxygen atom in acidic media disrupts such supramolecular association. The process is reversible and, consequently, can be used to switch on and off the self-assembly process. Hammett acidity measurements gave p[K.sub.a] values of-3.2 for the protonated molecules. Adducts with HCl and HBr were isolated and structurally characterized. Protonation in solution led to the crystallization of a new polymorph of 3-methyl-5-phenyl-1,2- tellurazole N-oxide, which features a unique polymeric arrangement. Key words: sigma-hole interactions, secondary bonding, chalcogens, supramolecular chemistry, main-group chemistry. Les isotellurazoles N-oxydes sont des synthons supramoleculaires prometteurs. Bien qu'en solution neutre, ils forment des agregats macrocycliques tetrameriques et hexameriques retenus par des liaisons secondaires Te ... O (interactions de trous t ou liaisons chalcogene), en milieu acide, la protonation des atomes d'oxygene perturbe une association supramoleculaire de ce type. Ce processus d'association est reversible et peut donc etre utilise pour provoquer ou inhiber le processus d'autoassamblage. Nous avons calcule, pour les molecules protonees, une valeur de p[K.sub.a] de -3,2 derivee des mesures de l'acidite en utilisant l'equation de Hammett. En outre, nous avons isole des adduits de HCl et de HBr et en avons caracterise les structures. La protonation en solution a entraine la cristallisation d'un nouveau polymorphe du 3-methyl-5-phenyl-1,2-tellurazole Noxyde presentant une structure polymerique unique. [Traduit par la Redaction] Mots-cles : interactions de trous sigma, liaison secondaire, chalcogenes, chimie supramoleculaire, chimie du groupement principal., Introduction The remarkable success of halogen bonding (1-4) in areas as diverse as crystal engineering, (2,5-14) supramolecular catalysis, (15) anion recognition, (16) optical materials, (17) and biomimetic chemistry (18-20) has [...]

Reaction of 2 equivalents of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] (cod = 1,5-cyclooctadiene) afforded [{κ2P,P-(Me3Al)ClMeAl(CH2PMe2)2}Rh(cod)] (1), which features a κ2-coordinated bis(phosphino)aluminate anion. In compound 1, an Al–Cl substituent bridges to a molecule of AlMe3, which could be removed in vacuo to provide [{κ2P,P-ClMeAl(CH2PMe2)2}Rh(cod)] (2). By contrast, reaction of 1 equiv. of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] yielded [Rh(cod)(μ-Cl)(Me2PCH2AlMe2)] (3) as the major product, where the phosphine donor of an intact Me2PCH2AlMe2 ligand is coordinated to rhodium and a chloride ligand bridges between Rh and Al. [Rh(cod)(μ-Cl)(Me2PCH2AlClMe)] (3A) and 2 were also formed as minor products. The aforementioned reactions were carried out in benzene or toluene, whereas the 1 : 1 reaction of (Me2PCH2AlMe2)2 with [{RhCl(cod)}2] in THF afforded [{Rh(μ-CH2PMe2)(cod)}2] (4). Reactions of (Me2PCH2AlMe2)2 with iridium(I), gold(I) and platinum(II) precursors were also explored. A 1 : 1 reaction of (Me2PCH2AlMe2)2 with [{IrCl(cod)}2] afforded [{κ2P,P-Cl2Al(CH2PMe2)2}Ir(cod)] (5) as one of two major phosphine-containing products; unlike 3, this compound features two chlorine substituents on aluminium. For comparison, the rhodium analogue of 5, [{κ2P,P-Cl2Al(CH2PMe2)2}Rh(cod)] (6), was also synthesized via the 1 : 1 reaction of {ClAl(CH2PMe2)2}2 with [{RhCl(cod)}2]. Reactions of (Me2PCH2AlMe2)2 with [AuCl(CO)] or [PtCl2(cod)] also resulted in chloride–methyl group exchange between the transition metal and aluminium. However, these reactions generated free (Me2PCH2AlClMe)2 accompanied by gold and ethane, or [PtMe2(cod)], respectively. Reaction of 1.5 equivalents of (Me2PCH2AlMe2)2 with [PtMe2(cod)] at 75 °C afforded zwitterionic [(PtMe{μ-κ1P:κ2P,P-MeAl(CH2PMe2)3})2] (7) which features two tris(phosphino)aluminate anions bridging between PtMe units. Compounds 1–2, 3/3A, 4–7 and (Me2PCH2AlClMe)2 were crystallographically characterized. [ABSTRACT FROM AUTHOR]

Reactions of trans-[(dmpe)2MnH(C2H4)] (1) with BH3(NMe3), 9-BBN, and HBMes2 yielded the manganese(I) borohydride complexes [(dmpe)2Mn(μ-H)2BR2] (3: R = H, 4: R2 = C8H14, 5: R = Mes). The reaction of 1 with BH3(NMe3) proceeds via ethylene substitution. By contrast, a detuerium labelling study indicates that the reaction of 1 with HBMes2 involves initial isomerization of 1 to an unobserved 5-coordinate ethyl intermediate, [(dmpe)2MnEt], which reacts with the hydroborane to afford EtBR2 and [(dmpe)2MnH], followed by reaction with a second equivalent of hydroborane to generate 5 (an analogous pathway is likely followed for other base-free hydroboranes such as 9-BBN). Identification of 3–5 as κ2-borohydride complexes, as opposed to boryl dihydride or hydroborane hydride isomers, is supported by 11B NMR spectroscopy, X-ray diffraction, and Atoms in Molecules calculations. Two byproducts were observed in the syntheses of 3–5: [{(dmpe)2MnH}2(μ-dmpe)] (6) and [(dmpe)2MnH(κ1-dmpe)] (7). These complexes were independently prepared by exposure of 1 to free dmpe under an atmosphere of Ar or H2, and the generality of this synthetic route was demonstrated by the reaction of 1 with PMe3 (under H2) to form [(dmpe)2MnH(PMe3)] (8). Complexes 6–8 can exist as isomers with either a trans or a cis relationship between the hydride and κ1-coordinated phosphine ligands on manganese. trans to cis isomerization of 6–8 is photochemically induced, whereas the reverse reaction occurs under thermal conditions. X-ray crystal structures were obtained for 3–5, trans,trans-6 , cis,cis-6 , trans-7 , and trans-8. [ABSTRACT FROM AUTHOR]

Reaction of NacNacAl (NacNac=[DippNC(Me)CHC(Me)NDipp]−) with one equivalent of benzophenone affords a ketylate species NacNacAl(η2(C,O)‐OCPh2) that undergoes easy cyclization reactions with unsaturated substrates. The scope of substrates included benzophenone, aldimine (PhNC(Ph)H), quinoline, phenyl nitrile, trimethylsilyl azide, and a saturated cyclic thiourea. The latter substrate reacted by an unusual C−N cleavage that left the C=S functionality intact. The new products were characterized by NMR spectroscopy and X‐ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The reactions of iso-tellurazole N-oxides with monocations of the coinage metals yielded a family of coordination complexes with a remarkable variety of compositions and structures. All new species were identified by single-crystal X-ray diffraction. In all cases, the macrocyclic aggregation of the organo-chalcogen heterocycles through Te⋯O chalcogen bonding interactions is preserved and the metal ions are coordinated by tellurium. Copper and gold formed complexes with the tetramers. The lighter element acquired a κ4Te,κ1O pentacoordinated square pyramidal structure with a triflate anion in the apical position. The preference of the heavier metal for a linear κ1Te,κ1Cl coordination geometry permitted the formation of a binuclear complex. Silver demonstrated a unique preference for coordinating to the hexamer; two distinct examples showed a structure with a pair of endocyclic κ2Te,κ2O metal ions bridged by two triflate anions; the other two chalcogen atoms are located at trans-annular positions and each coordinates a κ1Te,κ1O,κ1C silver ion, also bonded to an aromatic carbon and another triflate anion. [ABSTRACT FROM AUTHOR]