George Ferguson

meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetra­azacyclotetradecane as a building block in supramolecular chemistry; salts formed with 2,2′-biphenol, 4,4′-biphenol, 4,4′-thiodiphenol, 4,4′-sulfonyldiphenol, 3- and 4-hydroxybenzoic acids, 3,5-dihydroxybenzoic acid and phenylphosphonic acid; supramolecular structures in zero, one, two and three dimensions

The structure of meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraxadazacyclotetradecane–2,2′-biphenol (1/2), (C16H36N4).(C12H10O2)2 (1), is a salt [C16H38N4]2+.2[HOC6H4C6H4O]−: the cations are centrosymmetric with two protons held within the N4 cavity of the macrocycle by N—H⋯N hydrogen bonds, and the phenolate anions contain intramolecular O—H⋯O− hydrogen bonds. The ions are linked into a finite centrosymmetric aggregate by means of N—H⋯O hydrogen bonds. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-thiobiphenxadol–methanol (1/2/2), (C16H36N4).(C12H10O2S)2.(CH4O)2 (2), and meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-sulfonylbiphexadnol–methanol (1/2/2), (C16H36N4).(C12H10O4S)2.(CH4O)2 (3), are isomorphous: each is a salt, [C16H38N4]2+.2[HOC6H4SC6H4O]−.2MeOH (2) and [C16H38N4]2+.2[HOC6H4SO2C6H4O]−.2MeOH (3), and in each the phenolate anions are linked by O—H⋯O− hydrogen bonds into chains; antiparallel pairs of chains are cross-linked by the cations to form molecular ladders, with neutral methanol molecules acting as spacer units. In meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–3-hydroxybenzoic acid–methanol (1/2/2) (4), 3-hydroxybenzoate anions form chains, again cross-linked in pairs by the [C16H38N4]2+ cations to form molecular ladders, different from those in (2) and (3) in that the neutral methanol units are pendent from the ladders, rather than forming a part of it. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4-hydroxybenzoic acid–methanol (1/2/1) (5) is again a salt, [C16H38N4]2+.2[HOC6H4COO]−.MeOH: chains of 4-hydroxybenzoate anions are continuously cross-linked by two different types of [C16H38N4]2+ cation into a two-dimensional net. Only one of the two types of cation is linked to the chains via neutral methanol spacer units. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–phenylphosphonic acid–water (1/4/2) (6) is a salt, [C16H40N4]4+.4[C6H5PO3H]−.2H2O, containing the centrosymmetric tetra-protonated amine units, which have a conformation quite different from the trans-III conformation uniformly found in the [C16H38N4]2+ cations. The phenylphosphonate anions and the water molecules are linked into chains of fused rings, which are linked by the cations into two-dimensional nets. In meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane–3,5-dihydroxybenzoic acid (1/2) (7), the 3,5-dixadhydroxybenzoate anions in the unsolvated salt [C16H38N4]2+.2[(HO)2C6H3COO]− are linked into continuous two-dimensional nets, which are in turn linked by the centrosymmetric cations to form a three-dimensional framework. meso-5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane–4,4′-biphenol (1/3) (8) is a salt containing both neutral and anionic biphenol units, [C16H38N4]2+.2[HOC6H4C6H4O]−.[HOC6H4C6H4OH]. The two types of biphenol unit form two-dimensional nets and these nets are linked by the cations to form three independent, three-dimensional frameworks which are fully interwoven, but not bonded to one another.

Chain, sheet and framework structures in the adducts of phenylphosphonic acid with 4,4'-bipyridyl (1/1), piperazine (2/1) and 1,4-diazabicyclo[2.2.2]octane (2/1)

Phenylphosphonic acid–4,4′-bipyridyl (1/1), (1), C6H7O3P.C10H8N2, triclinic, P1¯, a = 6.9026u2005(8), b = 9.7086u2005(9), c = 12.201u2005(2)u2005A, α = 77.138u2005(9), β = 74.345u2005(10), γ = 75.477u2005(8)°, with Z = 2, is a salt, C10H9N2+.[C6H5PO2(OH)]−, containing singly protonated 4,4′-bipyridyl cations: the cations and anions are linked by N—H⋯O and C—H⋯O hydrogen bonds in an R^{2}_{2}(7) motif and these aggregates are linked into centrosymmetric R^{2}_{2}(8) dimers by O—H⋯O hydrogen bonds; the dimer units are linked into chains by C—H⋯O hydrogen bonds. Phenylphosphonic acid–piperazine (2/1), (C6H7O3P)2.C4H10N2 (2), monoclinic, P21/n, a = 6.0042u2005(9), b = 19.746u2005(3), c = 8.651u2005(2)u2005A, β = 105.63u2005(2)°, with Z = 2, is a salt, C4H12N22+. [{C6H5PO2(OH)}−]2, containing doubly protonated piperazine: the anions are linked by O—H⋯O hydrogen bonds into centrosymmetric R^{2}_{2}(8) dimers and these dimers are linked to the centrosymmetric cations by N—H⋯O hydrogen bonds: each cation is hydrogen-bonded to four different anion dimers and each anion dimer is hydrogen-bonded to four different cations; the overall structure consists of two-dimensional sheets built from R^{4}_{6}(16) and R^{4}_{4}(18) rings. Phenylphosphonic acid–1,4-diazabicyclo[2.2.2]octane (2/1), (3), (C6H7O3P)2.C6H12N2, monoclinic, P21/n, a = 6.3607u2005(3), b = 21.8300u2005(11), c = 14.5965u2005(9)u2005A, β = 92.558u2005(6)°, with Z = 4, is a salt in which one nitrogen of the diamine is fully protonated and the other is partially protonated: the anionic components are linked into C(4) chains by O—H⋯O hydrogen bonds, and these chains are cross-linked via the diamines by means of N—H⋯O and O—H⋯N hydrogen bonds. The resulting sheets built from R^{8}_{8}(34) rings are linked by C—H⋯O hydrogen bonds into a three-dimensional framework.

Crystal Engineering Using Bis- and Tris-phenols. Adducts with 1,4,8,11-Tetraazacyclotetradecane (Cyclam): Isolated Ladders in the Adduct with 4,4'-Thiodiphenol, Tethered Ladders in the Adduct with 4,4'-Sulfonyldiphenol and Two Interwoven Three-Dimensional Networks in the Adduct with 1,1,1-Tris(4-hydroxyphenyl)ethane

The structure of 4,4′-thiodiphenol–1,4,8,11-tetraazacyclotetradecane (2/1), (C12H10O2S)2.C10H24N4 (1), monoclinic, P21/c, a = 11.1602u2005(12), b = 10.8084u2005(12), c = 14.001u2005(2)u2005A, β = 103.127u2005(10)°, with Z = 2, contains phenolate anions [HOC6H4SC6H4O]− and diprotonated cyclam cations [C10H26N4]2+: these cations have the centrosymmetric trans-III conformation and the two additional protons are contained within the N4 cavity of the macrocycle, held by three-centre hydrogen bonds. The phenolate anions form chains, held together by O—H⋯O hydrogen bonds, and pairs of these chains are cross-linked into ladders by the [cyclamH2]2+ cations by means of N—H⋯O hydrogen bonds. The structure of 4,4′-sulfonyldiphenol–1,4,8,11-tetraazacyclotetradecane (2/1), (C12H10O4S)2.C10H24N4 (2), triclinic, P1¯, a = 10.9345u2005(10), b = 11.0060u2005(10), c = 14.350u2005(2)u2005A, α = 79.532u2005(10), β = 86.739u2005(10), γ = 87.471u2005(10)°, with Z = 2, contains phenolate anions [HOC6H4SO2C6H4O]− and cyclam dications [C10H26N4]2+: the phenolate anions are linked into antiparallel chains, cross-linked by the cyclam cations. There are two distinct types of ladder in the structure running along (0, y, 0) and (1over2, y, 1over2), respectively, and these bundled ladders are tied together by C—H⋯O hydrogen bonds to form a continuous three-dimensional array. In 1,1,1-tris(4-hydroxyphenyl)ethane–1,4,8,11-tetraazacyclotetradecane–methanol (2/1/1), (C20H18O3)2.C10H24N4.CH4O (3), triclinic, P1¯, a = 8.2208u2005(11), b = 16.245u2005(2), c = 17.337u2005(2)u2005A, α = 81.694u2005(13), β = 89.656u2005(14), γ = 86.468u2005(12)°, with Z = 2, the structure contains centrosymmetric diprotonated cyclam cations of precisely the same type as found in (1), phenolate anions [(HOC6H4)2C(CH3)C6H4O]− and neutral methanol molecules. The molecular components are linked together by nine different types of hydrogen bond, five of O—H⋯O type and four of N—H⋯O type, to form chains running in the [001], [010] (two sets), [211] and [211¯] directions. The combination of these chain motifs generates two independent three-dimensional networks which are fully interwoven, but not bonded to one another.

Hydrogen-bonding behaviour of benzene-1,2,4,5-tetracarboxylic acid: supramolecular structures of different dimensionality in the 2:1 adducts formed with 4,4′-bipyridyl and hexamethylenetetramine

Co-crystallization of benzene-1,2,4,5-tetracarboxylic acid, C10H6O8, with 4,4-bipyridyl, C10H8N2, or with hexamethylenetetramine, C6H12N4, from methanol solutions yields in each case a 2:1 salt, [(C10H9N2)+]2.[(C10H4O8)2-] (1) and [(C6H13N4)+]2.[(C10H4O8)2-] (2). In (1) the carboxylate anions lie across centres of inversion, but they contain no intramolecular O-H...O hydrogen bonds: the cations and anions are linked by strong O-H...N and N-H...O hydrogen bonds into a chain-of-rings, and these chains are further linked into a three-dimensional framework structure by means of C-H...O hydrogen bonds and aromatic pi...pi stacking interactions. Compound (2) contains two independent three-molecule aggregates, comprising a central anion and two cations, linked to the anion by means of short N-H...O hydrogen bonds. One of these aggregates is centrosymmetric, but the other is not, and the two types of anion both form two intramolecular O-H...O hydrogen bonds. The two types of three-molecule aggregate, in which all the anions are virtually parallel, are linked by short C-H...O hydrogen bonds into a molecular staircase.

Ferrocene-1,1′-dicarboxylic acid as a building block in supramolecular chemistry: supramolecular structures in one, two and three dimensions

The supramolecular structures have been determined for nine adducts formed between organic diamines and ferrocene-1,1-dicarboxylic acid. In the salt-like 1:1 adduct (1) formed with methylamine, the supramolecular structure is one-dimensional, whereas in the 1:1 adducts formed with 1,4-diazabicyclo[2.2.2]octane, (2), and 4,4-bipyridyl, (4), and in the hydrated 2:1 adduct (3) formed with morpholine, the hard hydrogen bonds form one-dimensional structures, which are expanded to two dimensions by soft C-H...O hydrogen bonds. The hard hydrogen bonds generate two-dimensional structures in the 2:1 adduct (5) formed with octylamine, where the ferrocene component lies across a centre of inversion, in the 1:1 adduct (6) formed with piperidine and in the tetrahydrofuran-solvated 1:1 adduct (7) formed with di(cyclohexyl)amine. In the 2:3 adduct (8) formed by tris-(2-aminoethyl)amine, and in the 2:1 adduct (9) formed with 2-(4-hydroxyphenyl)ethylamine (tyramine), where Z = 1.5 in space group P-1, the hard hydrogen bonds generate three-dimensional structures. No H transfer from O to N occurs in (4) and only partial transfer of H occurs in (2); in (1), (6) and (7), one H is transferred to N from each acid molecule, and in (3), (5), (8) and (9), two H are transferred from each acid molecule.

The 1 :1 adduct of triphenylsilanol and 4,4'-bipyridyl, and three pairwise-concomitant triclinic polymorphs of the 4 :1 adduct having Z' = 0.5, 1 and 4

Crystallization from methanol solution of mixtures of triphenylsilanol and 4,4-bipyridyl has given a 1:1 adduct (I), Ph(3)SiOH.C(10)H(8)N(2), and three polymorphic 4:1 adducts (II)-(IV), (Ph(3)SiOH)(4).C(10)H(8)N(2). In (I), the components are linked by a single O-H...N hydrogen bond and by a number of C-H...pi(arene) hydrogen bonds to form a continuous three-dimensional structure. Compounds (II)-(IV) are all triclinic, space group P-1, with Z values of 0.5, 1 and 4, respectively. The basic hydrogen-bonded aggregate is the same in each of (II)-(IV), having a pair of silanol molecules linked to the bipyridyl via O-N...N hydrogen bonds and a further pair of silanol molecules linked to the first pair via O-H...O hydrogen bonds. In (II) there is just one such aggregate lying across a centre of inversion (Z = 0.5) and in (III) there are two such aggregates, both lying across centres of inversion (Z = 2 x 0.5 = 1). In (IV) there are six independent aggregates of this type, four of which lie across centres of inversion and two of which lie in general positions, so that Z = (4 x 0.5) + 2 = 4. While the components in (I) are fully ordered, each of (II)-(IV) exhibits extensive disorder involving both the bipyridyl units and the phenyl rings of the silanol components.

Chiral versus racemic building blocks in supra­molecular chemistry: tartrate salts of organic diamines

In the 1:1 adducts C(12)H(10)N(2).C(4)H(6)O(6) formed between 1,2-bis(4-pyridyl)ethene and racemic tartaric acid [(I), triclinic P1;, Z = 1] and (2R,3R)-tartaric acid [(II), triclinic P1, Z = 2], the ionic components are linked by hard hydrogen bonds into single sheets, which are further linked by C-H.O hydrogen bonds. In the analogous adducts C(10)H(18)N(2).C(4)H(6)O(6) formed by 4,4-bipyridyl with racemic tartaric acid [(III), triclinic P1;, Z = 1] and the chiral acid [(IV), monoclinic P2(1), Z = 1], the hard hydrogen bonds generate bilayers which are again linked by C-H.O hydrogen bonds. Piperazine forms a 1:1 salt [((C(4)H(10)N(2))H(2))(2+)].[(C(4)H(4)O(6))(2-)] with (2R,3R)-tartaric acid [(V), monoclinic P2(1)] sheets, which are linked by the cations to form a pillared-layer framework. In each of the 1:2 salts formed by racemic tartaric acid with piperazine [(VI), monoclinic P2(1)/n, Z = 0.5] and 1,4-diazabicyclo[2.2.2]octane (DABCO) [(VII), monoclinic P2(1)/n, Z = 0.5], the cation lies across a centre of inversion, with the [(HN(CH(2)CH(2))(3)NH)(2+)] cation disordered over two sets of sites: in both (VI) and (VII) the anions form a three-dimensional framework encapsulating large voids which accommodate the cations. The salt formed between DABCO and (2R,3R)-tartaric acid [(VIII), orthorhombic P2(1)2(1)2(1), Z = 1] has 3:4 stoichiometry and contains four different types of ion, [(HN(CH(2)CH(2))(3)NH)(2+)](2).[N(CH(2)CH(2))(3)NH](+).3(C(4)H(5)O(6))(-).C(4)H(4)O(6)(2-): the hard hydrogen bonds generate a three-dimensional framework.

Investigation of the synthetic and mechanistic aspects of the highly stereoselective transformation of α-thioamides to α-thio-β-chloroacrylamides

Treatment of a series of α-thioamides with N-chlorosuccinimide results in efficient transformation to the analogous α-thio-β-chloroacrylamides. The mechanistic pathway has been established through isolation and characterisation of intermediate compounds. The scope of the transformation has been explored—aryl and alkylthio substituents, primary, secondary and tertiary amides can be employed. In most instances, the chloroacrylamides are formed exclusively as the Z-stereoisomer; however, with tertiary propanamides or with amides derived from butanoic or pentanoic acid a mixture of E- and Z-stereoisomers is formed.

Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines

(S)-Malic acid forms a salt with N,N-dimethylpiperazine, [MeN(CH(2)CH(2))(2)NMe]H(2)(2+) x 2C(4)H(5)O(5)(-) (1) (triclinic, P1, Z = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z = 1) and (3) (monoclinic, C2, Z = 1), while racemic malic acid with 4,4-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P2(1)/c, Z = 1). In each of (2), (3) and (4) the components are linked by O[bond]H...N and N[bond]H...O into chains of alternating bipyridyl and malate units, which are linked into sheets by O[bond]H...O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic acid and racemic malic acid with 1,2-bis(4-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180 degrees rotation about the N...N vector. In (5), (C(12)H(10)N(2))H(+) x C(4)H(5)O(5)(-) (triclinic, P1, Z = 1), the components are again linked by a combination of N[bond]H...O and O[bond]H...O hydrogen bonds into sheets, while in (6) (triclinic, P1;, Z = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic acid forms a 1:2 salt, [(C(6)H(12)N(2))H(2)](2+).2C(4)H(5)O(5)(-) (7) (monoclinic, P2(1)/c, Z = 2), while (S)-malic acid forms a 1:1 adduct, (8) (monoclinic, P2(1), Z = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N[bond]H...O and O[bond]H...O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible.

Simple hydrogen-bonded chains in 2,2'-bipyridinium thiocyanate, hydrogen-bonded chains of rings in 2,2'-bipyridinium picrate and hydrogen-bonded sheets in 2,2'-bipyridinium hydrogensulfate

In 2,2′-bipyridinium thioxadcyanate, C10H9N2+·NCS−, the cations are disordered over two sets of sites with occupancies of 0.845u2005(2) and 0.155u2005(2). The ions are linked into simple chains by a combination of N—H⋯N and C—H⋯N hydrogen bonds, regardless of the orientation of the cation. In 2,2′-bipyridinium picrate, C10H9N2+·C6H2N3O7−, the bond distances in the anion indicate a markedly non-classical electronic structure; the component ions are linked by a combination of six independent hydrogen bonds, viz. one of N—H⋯O type and five of C—H⋯O type, into a complex chain containing five distinct types of ring. The ions in 2,2′-bipyridinium hydrogensulfate, C10H9N2+·HSO4−, are linked by a combination of five hydrogen bonds, viz. one each of O—H⋯O and N—H⋯O types, and three of C—H⋯O type, into complex sheets built from two one-dimensional substructures, each in the form of a complex chain of rings.