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© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The first transition metal catalyzed hydrophosphination of isocyanates is presented. The use of low-coordinate iron(II) precatalysts leads to an unprecedented catalytic double insertion of isocyanates into the P−H bond of diphenylphosphine to yield phosphinodicarboxamides [Ph2PC(=O)N(R)C(=O)N(H)R], a new family of derivatized organophosphorus compounds. This remarkable result can be attributed to the low-coordinate nature of the iron(II) centers whose inherent electron deficiency enables a Lewis-acid mechanism in which a combination of the steric pocket of the metal center and substrate size determines the reaction products and regioselectivity.

The application of pressures of up to about 10 GPa may induce significant geometric, configurational, conformational and packing changes in molecular solids. This review highlights and describes recent advances in high pressure studies of coordination complexes, many of which have been conducted at synchrotrons or other central facilities. The main focus is on the wide range of geometric changes which occur with pressure. In some cases these changes have associated physical effects, and the review describes materials exhibiting negative linear compressibility, spin cross-over phenomena, magnetism and molecular conduction, as well as detailing the exciting possibilities for future developments in this area of research.

(Chemical Equation Presented) A straightforward oxidation strategy affords the first pentavalent uranium carbene complex, 2. Owing to the structural similarity of 1 and 2, it was possible for the first time to directly probe the differences in U=C bonding on oxidation of UIVto UV. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA

The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(Tren(TIPS) )}2 (μ-η(2) :η(2) -As2 H2 )] (3, Tren(TIPS) =N(CH2 CH2 NSiPr(i) 3 )3 ; Pr(i) =CH(CH3 )2 ). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH π*-orbital. This experimentally confirms the theoretically predicted excellent π-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form.

The amidoamines (S)-Ar1CONHCHRCH2NHAr2 [Ar1 = o-C6H4SO3H, R = Bn, iBu, iPr; Ar2 = 2,6-iPr2C6H4, 2,6-Et2C6H4, 2,4,6-Me3C6H2] cyclise to (S) 1-aryl-substituted 4,5-dihydro-1H-imidazolinium species with HC(OEt)3 in moderate-to-excellent yields on heating to 150–175 °C (nine examples, four isolated yields of 48 to >97 %). They are attained as their o-C6H4(SO3–)(CO2Et) salts. The latter are readily deprotonated to afford analytically pure (S) 1-aryl-substituted 4,5-dihydro-1H-imidazoles (imidazolines). The purification of the intermediate sulfonate salts is not always necessary, and analytically pure imidazolines are isolated by simple kugelrohr distillation (nine examples, 45–95 %) after basification. Imidazoline alkylation provides a library of (S)-N-alkylimidazolinium salts (23 examples, 74–97 %). As the initially required amidoamines are available in simple one-pot reactions, the overall approach constitutes a rather efficient approach to this useful family of chiral N-heterocyclic carbene (NHC) ligand precursors (effectively three steps from commercial N-Boc-α-amino alcohols; BOC = tert-butyloxycarbonyl).

Reaction of [U(Tren(TIPS))] [1, Tren(TIPS)=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(Tren(TIPS))}2(μ-η(5):η(5)-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals.

Regioselective enolate formation, followed by stereoselective electrophilic quenching of unsymmetrical proline-derived diketopiperazines (DKPs), enabled the synthesis of variously substituted DKPs, including one substrate which could be further substituted and cyclised to give the bicyclo[2.2.2]diazaoctane core structure present in paraherquamide and stephacidin natural products.

A synthesis of model DEF-rings of the polyketide anti tumor natural products FR182877 and hexacyclinic acid has been achieved. The key steps in the synthesis are an intramolecular Pd(0) catalyzed allylic substitution reaction, which was used to generate a 9-membered carbocycle, and a novel transannular iodocyclization reaction which furnished the DF-rings of both natural products.

Non‐CsCl topologies for eight‐connected solid‐state materials have been observed for the first time in three networks based on lanthanide cations and 4,4′‐bipyridine‐N,N′‐dioxide ligands. The structure of the {[Yb(L)4](CF3SO3)3}∞ network is depicted.

Organolanthanides with amido‐tethered N‐heterocyclic carbenes: a new bidentate ligand that tethers an N‐heterocyclic carbene group to a trivalent lanthanide complex (samarium, depicted, N′′=N(SiMe3)2; or yttrium) affords the first organolanthanide amido–carbene complexes and an opportunity to explore the strength and reactivity of the early metal–N‐heterocyclic carbene fragment.

The synthesis of a range of thiazole containing cyclic peptides using cyclooligomerisation reactions of amino acid substituted thiazole monomers and by macrolactamisation procedures is reported. The synthetic approaches lead to high yields of novel 18- and 24-membered ring analogues of the naturally occurring Lissoclinum families of cyclic peptides found in marine organisms and algae.

In the title compound [systematic name: (1Z,3Z)-1,3-dihydrazinylidene-1H-inden-2(3H)-one], C9H8N4O, isolated molecules possess approximate noncrystallographicC2vsymmetry and theircisconformation and planarity are assisted by a pair of short intramolecular N—H...O hydrogen bonds. Each molecule is asymmetrically involved in an extensive three-dimensional network of N—H...O and N—H...N hydrogen bonds, and the structure also exhibits weaker π–π and C=O...C interactions. The structure features anR44(12) motif consisting solely of N and H atoms and possessing crystallographic \overline{4} symmetry.

In the title compounds, [N-(phenyl(2-[N-(S)-(2-picolyl)prolylamino]phenyl)methylene)-(S)-phenylalaninato]nickel(II), [Ni(C(33)H(30)N(4)O(3))], (I), [N-(phenyl(2-[N-(S)-(3-picolyl)prolylamino]phenyl)methylene)-(S)-phenylalaninato]nickel(II) hemihydrate, [Ni(C(33)H(30)N(4)O(3))].0.5H(2)O, (II), and [N-((2-[N-(S)-ethylprolylamino]phenyl)phenylmethylene)-(S)-phenylalaninato]nickel(II), [Ni(C(29)H(29)N(3)O(3))], (III), the Ni(II) centres have approximate square-planar coordination geometries from N(3)O donor sets. The picolyl N atoms in (I) and (II) are too remote from the metal centres to interact significantly, but the metal coordination geometries experience tetrahedral distortion and/or displacement of the metal centre from the N(3)O plane. These are linked to conformational differences between the ligands of the symmetry-independent complexes (Z' = 2), which in turn are related to molecular packing. In (III), where a less sterically demanding ethyl group replaces the picolyl substituents, there are none of the distortions or displacements seen in (I) and (II).

International audience; Two‐electron reductive carbonylation of the uranium(VI) nitride [U(TrenTIPS)(N)] (2, TrenTIPS=N(CH2CH2NSiiPr3)3) with CO gave the uranium(IV) cyanate [U(TrenTIPS)(NCO)] (3). KC8 reduction of 3 resulted in cyanate dissociation to give [U(TrenTIPS)] (4) and KNCO, or cyanate retention in [U(TrenTIPS)(NCO)][K(B15C5)2] (5, B15C5=benzo‐15‐crown‐5 ether) with B15C5. Complexes 5 and 4 and KNCO were also prepared from CO and the uranium(V) nitride [{U(TrenTIPS)(N)K}2] (6), with or without B15C5, respectively. Complex 5 can be prepared directly from CO and [U(TrenTIPS)(N)][K(B15C5)2] (7). Notably, 7 reacts with CO much faster than 2. This unprecedented f‐block reactivity was modeled theoretically, revealing nucleophilic attack of the π* orbital of CO by the nitride with activation energy barriers of 24.7 and 11.3 kcal mol−1 for uranium(VI) and uranium(V), respectively. A remarkably simple two‐step, two‐electron cycle for the conversion of azide to nitride to cyanate using 4, NaN3 and CO is presented.

The ketimide anion R2C[DOUBLE BOND]N− is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N− amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPMTMS){N(SiMe3)2}(N[DOUBLE BOND]CPh2)] [2, BIPMTMS=C(PPh2NSiMe3)2]. Complex 2 contains Th[DOUBLE BOND]Ccarbene, Th[BOND]Namide and Th[BOND]Nketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the Th[BOND]Nketimide bond rather than at the Th[DOUBLE BOND]Ccarbene or Th[BOND]Namide bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators.

We report the uranium(VI) carbene imido oxo complex [U(BIPM TMS)(NMes)(O)(DMAP)2] (5, BIPMTMS=C(PPh 2NSiMe3)2; Mes=2,4,6-Me3C 6H2; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPM TMS)(O)2(DMAP)2] (6). Three not of a kind: An unprecedented arrangement of three formal multiply bonded ligands to one metal center, where the coordinated heteroatoms derive from different element groups, is found in the uranium(VI) carbene imido oxo complex [U(BIPM TMS)(NMes)(O)(DMAP)2] (Mes=2,4,6-Me3C 6H2). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reaction of [U(TrenTIPS)(THF)][BPh4] (1; Tren TIPS=N{CH2CH2NSi(iPr)3} 3) with NaPH2 afforded the novel f-block terminal parent phosphide complex [U(TrenTIPS)(PH2)] (2; U-P=2.883(2)?Å). Treatment of 2 with one equivalent of KCH 2C6H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded the unprecedented metal-stabilized terminal parent phosphinidene complex [U(TrenTIPS)(PH)][K(B15C5)2] (4; UP=2.613(2)?Å). DFT calculations reveal a polarized-covalent UP bond with a Mayer bond order of 1.92. Straightforward deprotonation of the first f-block terminal parent phosphide complex and potassium abstraction results in the isolation of an unprecedented structurally authenticated metal-stabilized terminal parent phosphinidene complex. B15C5=benzo-15-crown-5 ether. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Almost linear I-Se-Br groups with d(Se-Br)>d(Se-I) occur in 1⋅2 IBr, the first "T-shaped" Se adduct with IBr, which was synthesized by the oxidative addition of IBr to 1,2-bis(3-methylimidazoline-2-selonyl)ethane (1) in MeCN. Density functional theory calculations indicate the intramolecular Br⋅⋅⋅H interactions as being responsible for the peculiar structural features of the I-Se-Br groups.

The novel bicyclic and tricyclic systems di­methyl (4aS*,6S*)-6-methoxy-7-oxo-4a,5,6,7,8,9-hexa­hydro-2H-benzo­cyclo­hept­ene-3,4-di­carboxyl­ate, C16H20O6, (I), di­methyl (4aS*,6R*)-6-methoxy-7-oxo-4a,5,6,7,8,9-hexa­hydro-2H-benzo­cyclo­hept­ene-3,4-di­carboxyl­ate, C16H20O6, (II), (3aS*,9R*,10aS*,10bR*)-9-methoxy-2-oxa-1,3a,4,6,7,8,9,10,10a,10b-deca­hydro-3H-cyclo­hepta­[e]­indene-1,3,8-trione, C14H16O5, (III), and (1S*,2R*,9S*,10aR*)-9-methoxy-8-oxo-1,2,3,5,6,7,8,9,10,10a-deca­hydrobenzo­cyclo­octene-1,2-di­carboxyl­ic acid, C15H20O6, (IV), have been crystallographically characterized, allowing the determination of the relative configuration of the stereogenic centres. The poor quality of the di­carboxyl­ic acid crystals necessitated the use of synchrotron radiation.

Eight-coordinate metal-ion nodes are linked through 4,4-bipyridine-N,N'-dioxide (L) ligands to form the first examples of eight- and seven-connected coordination networks. Thus, whereas [La(L)4 ](CF3 SO3 )3 adopts an eight-connected body-centered hypercubic CsCl-like lattice, [La(L)4 ](BPh4 )(ClO4 )2 shows eight-coordinate, but seven-connected, nodes linked in an unprecedented 417 62 topology.

The single-crystal X-ray structures of dimethyl 2,2'-bipyridine-6,6'-dicarboxylate, C(14)H(12)N(2)O(4), and the copper(I) coordination complex bis(dimethyl 2,2'-bipyridine-6,6'-dicarboxylato-kappa(2)N,N')copper(I) tetrafluoroborate, [Cu(C(14)H(12)N(2)O(4))(2)]BF(4), are reported. The uncoordinated ligand crystallizes across an inversion centre and adopts the anticipated anti pyridyl arrangement with coplanar pyridyl rings. In contrast, upon coordination of copper(I), the ligand adopts an arrangement of pyridyl donors facilitating chelating metal coordination and an increased inter-pyridyl twisting within each ligand. The distortion of each ligand contrasts with comparable copper(I) complexes of unfunctionalized 2,2'-bipyridine.

In the title compound, trans-dichloro(1,5,9,13-tetrathiacyclohexadecane-κ 4 S)rhodium(III) pentaiodide diiodine, [RhCl 2 (C 12 H 24 S 4 )](I 5 ).I 2 the complex cations are embedded in a three-dimensional polyiodide matrix composed of cages of I 5 - ions and I 2 molecules interacting via I...I contacts which range from 3.336 (2) to 4.133 (2) A.

The theoretical equilibrium and X-ray crystallographic structures of 3-methyl-1,2,4-triazine, C 4 H 5 N 3 S, show a high level of agreement. The calculated charge distributions are analysed for each of four conformers; that with lowest energy is present both in the solid and in mesitylene solution, as shown by dipole-moment measurements.

The structure of bis(1,4,7-trithiacyclononane)palladium(II) bis(dibromoiodide), [Pd(C 6 H 12 S 3 ) 2 ](IBr 2 ) 2 , comprises ribbons in which neighbouring cations are linked by pairs of anions through S...Br contacts of 3.767 (5)-3.877 (5) A. In (1,4,8,11-tetrathiacyclotetradecane)palladium(II) bis(dibromoiodide), [Pd(C 10 H 20 S 4 )](IBr 2 ) 2 , Pd...I, S...Br and S...I contacts link cations and anions into an infinite three-dimensional network.

In the first title compound, [Ni(C 2 H 3 N) 2 (C 11 H 26 N 4 )](I 3 ) 2 , the Ni II centre is coordinated octahedrally: all four N-donor atoms of the macrocyclic ligand occupy an equatorial plane and the coordination is completed by two axial acetonitrile ligands. Each N-H group forms a contact of 2.97-3.11 A to one I atom of an I 3 - anion. One of these anions participates in long I. . .I contacts of 4.008(3)A to form infinite chains of symmetry-related anions. In the second title compound, [Pd(C 11 H 26 N 4 )](I 3 ) 2 , each Pd II centre is coordinated in an equatorial plane by four N-donor atoms from the macrocyclic ligand and axially by a terminal iodine from each of two I 3 - anions at 3.525 (4) A. The same I atom forms an I...I contact of 4.094(3) A such that cations and pairs of anions alternate within one-dimensional zigzag chains.

Mit den Kationen [Pd2Cl2L]2+ und [KL]+ (L[18]anN2S4, L′ = [15]anO5) als Templaten sind neuartige dreidimensionale Polyiodid-Netzwerke zuganglich. Die Metallkationen in [Pd2Cl2L]1.5I5(I3)2 sind durch paarweise Wasserstoffbruckenbindung zu unendlichen Ketten verknupft, wobei die resultierenden kationischen Polymere in Kanalen eines ausgedehnten Polyiodid-Netzwerks liegen. [KL]I9 hat ein dreidimensionales Netzwerk aus deformierten wurfelformigen Kafigen aus I9−-Ionen, deren Hohlraume durch die Metallkationen besetzt sind (Ausschnitt aus der Struktur rechts gezeigt).

The structures of four azolyl-3-propenoic esters, methyl (E)-3-(imidazol-4-yl)propenoate, (2), as its hemihydrate, C 7 H 8 N 2 O 2 .0.5H2O, methyl (E)-3-(pyrrol-2-yl)-propenoate, C 8 H 9 NO 2 , (3), methyl (E)-3-(imidazol-2-yl)propenoate, C 7 H 8 N 2 O 2 , (4), and methyl (Z)-3-(imidazol-2-yl)propenoate, C 7 H 8 N 2 O 2 , (5), are reported. In the pyrrole and imidazole derivatives, (3) and (4), the N-H function has an s-Z configuration with respect to the propenoate chain, whereas in the urocanate, (2), protonation has occurred at the N atom further from the side chain. In (5), an intramolecular N-H...O hydrogen bond causes a relative widening of the angles in the side chain. In all four compounds, both the azole rings and the side chains are almost planar. In the hemihydrate of (2), there is extensive hydrogen bonding, primarily of the type N-H...O but supplemented by much longer C-H...O interactions. In (3) and (4), the hydrogen bonding is much simpler, with molecules linked into ribbons via N-H...O contacts.

The crystal structure of (±)-1,2;4,5-di-O-cyclohexylidene myo-inositol, refined to R = 2.9%, shows interestingly disordered (flip-flop) hydrogen bonding. The higher reactivity of the 1/3 positions (rather than 4/6) has been evaluated using semi-empirical calculations. This diol has been phosphorylated with (2R,4S,5R)-2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidin-2-one and the diastereoisomer derived from phosphorylation at the 3-position was isolated by crystallisation. Deprotection with TFA/H2O then H2/Pd-C afforded myo-inositol 3-phosphate in only four steps from myo-inositol.

Application of modern synthetic methods to the Maitland-Japp reaction has provided a one pot, one step procedure for the efficient construction of highly substituted tetrahydropyran-4-ones.

Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic "ate" cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon.

In both 3-(N,N-diisopropylamino)-2-propenal, C 9 H 17 NO, (3), and 3-(1,2,3,4-tetrahydro-1-quinolinyl)-2-propenal, C 12 H 13 NO, (4), the entire enaminal system (O1-C1-C2-C3-N4) is approximately planar. The angles around the N atoms in (3) and (4) sum to values near 360°, indicating planarity in both molecules. One of the two crystallographically independent molecules of (3) exhibits disorder in its isopropyl groups.

The structures of four simple pyridazin-3(2H)-ones, the isomeric 4-methylpyridazin-3(2H)-one [C5H6N2O (5)], 5-methylpyridazin-3(2H)-one monohydrate and 6-methylpyridazin-3(2H)-one monohydrate [C5H6N2O.H2O, (6).H2O and (7).H2O] and 2-(p-tolyl)pyridazin-3(2H-one [C11H10N2O (8)], have been determined. Compounds (6)–(7), which crystallize as monohydrates, show extensive bonding while molecules of (5) form hydrogen-bonded dimers. In (8) there are no strong hydrogen bonds as in compounds (5) and (7), the closest intermolecular contacts being pairwise C—H⋯O interactions.

The structure of the title compound {[HgCl2([18]aneS2O4)]HgCl2}n ([18]aneS2O4 = 1,4,7,10-tetraoxa-13,16-dithiacyclooctadecane), [Hg2Cl4(C12H24O4S2)], has been redetermined, and reinterpreted as a one-dimensional polymeric thread comprising linked Hg4Cl4 macrocyclic moieties with pendant macrocyclic ligands. {the compound may be named catena-poly[(chloromercury)-di-μ-chloro-bis[(1,4,7,10-tetraoxa-13,16-di-thiacyclooctadecane-S,S)mercury]-di-μ-chloro-(chloromercury)-di-μ-chloro]}.

Both 1,4,7-trioxa-10,13-dithiacyclopentadecane, C 10 H 20 O 3 S 2 , and 1,4,7,10-tetraoxa-13,16-dithiacyclooctadecane, C 12 H 24 O 4 S 2 , show exo-oriented S and endo-oriented O atoms. The torsion angle of the SCH 2 CH 2 S moiety is anti [-165.93 (8)°] in the former and gauche [60.0 (2)°] in the latter. The latter exhibits C 2 symmetry through the midpoints of the C3-C3' and C11-C11' bonds.

Molecules of 1,4,7,10,13-pentaoxa-16,19-dithiacyclohenicosane, [21]aneSS 2 O 5 , are linked in the sesquihydrate, C 14 H 28 O 5 S 2 .3/2H 2 O, via intermolecular O...H-O hydrogen-bonding interactions with the water of crystallization. The conformation of the macrocycle is discussed in terms of its potential as a multifunctional ligand.

The structures of a series of six 1-methyl-1H-2,3-benzodiazepine compounds, 1(R)-methyl-4-[1(R)-phenylethyl]-1H-2,3-benzodiazepine (C 18 H 18 N 2 ), (1), 1(R)-methyl-4-[1(R),2,2-trimethylpropyl]-1H-2,3-benzodiazepine (C 16 H 22 N 2 ), (2), 1(S)-methyl-4-[1(S)-ethyl-2,2-dimethylpropyl]-1H-2,3-benzodiazepine (C 17 H 24 N 2 ), (3), 1(R)-methyl-4-[1(R)-methoxybenzyl]-1H-2,3-benzodiazepine (C 18 H 18 N 2 O), (4), 1(S)-methyl-4-[1(R)-methoxy-2,2-dimethylpropyl]-1H-2,3-benzodiazepine (C 16 H 22 N 2 O), (5), and 1(R)-methyl-4-[1(R)-benzoyloxy-2,2-dimethylpropyl]-1H-2,3-benzodiazepine (C 22 H 24 N 2 O 2 ), (6), with differing substituents on the 4-position of the seven-membered diazepine ring, have been determined. [The IUPAC name for the ester (6) is 2,2-dimethyl-1-(1-methyl-1H-2,3-benzodiazepin-4-yl)propyl benzoate.]

Molecules of C 7 H 13 N 3 possess non-crystallographic C 3 symmetry. Their structure may be visualized as three five-membered CNCCN rings: each is in a twist conformation and shares edges with the other two rings and a common pivot C atom

The reaction of 1-thia-4,7-diazacyclononane with bromoacetyl bromide in CHCl 3 affords the unexpected salt 4-(2-bromoacetyl)-8-oxo-1-thionia-4,7-diazabicyclo[5.2.2]undecane bromide, C 10 H 16 BrN 2 O 2 S + .Br - . Two units of the salt are linked by S...Br contacts about a crystallographic inversion centre, thus forming dimers that are linked by Br...Br contacts into extended ribbons. S...O contacts between these ribbons generate a two-dimensional sheet.

New NHC ligand precursors are synthesized, which serve as highly active catalysts (turnover number about 100) for γ-selective additions to cinnamyl electrophiles without the need for metal salts.

The title complex, [Cu(ClO4)2(C9H13N5O)(CH3OH)], was synthesized from a methanolysis reaction ofN-(methylpyridin-2-yl)cyanoguanidine (L3) and copper(II) perchlorate hexahydrate in a 1:1 molar ratio. The CuIIion is six-coordinated by an N3O3donor set which confers a highly distorted and asymmetric octahedral geometry. Three N-donor atoms from the chelating 1-(methoxymethanimidoyl)-2-(pyridin-2-ylmethyl)guanidine (L3m) ligand and one O atom from the methanol molecule define the equatorial plane, with two perchlorate O atoms in the apical sites, one of which has a long Cu—O bond of 2.9074 (19) Å. The dihedral angle between the five- and six-membered chelate rings is 8.21 (8)°. Two molecules are associated into a dimeric unit by intermolecular N—H...O(perchlorate) hydrogen bonds. Additionally, the weakly coordinated perchlorate anions also link adjacent [Cu(ClO4)2(L3m)(CH3OH)] dimers by hydrogen-bonding interactions, resulting in a two-dimensional layer in the (100) plane. Further C—H...O hydrogen bonds link the two-dimensional layers along [100] to generate a three-dimensional network.

The structures of two derivatives of Meldrum's acid, 2,2-dimethyl-5-[N-(1-pyrrolyl)aminomethylene]-1,3-dioxane-4,6-dione, C 11 H 12 N 2 O 4 , (1), and 2,2-dimethyl-5-[N-(1-pyrazolyl)aminomethylene]-1,3-dioxane-4,6-dione, C 10 H 11 N 3 O 4 , (2), which differ only at one position in the five-membered ring, are described