Caroline A. O'Mahoney

Single crystal X-ray diffraction studies of aromatic oligomers: resolution of the bond-angle anomaly in poly(aryletherketone)s

Abstract To resolve long-standing uncertainties surrounding the bridge-bond angles of crystalline poly(aryletherketone)s, the structure of an oligomeric ether-ketone, ClArCOArOArCOArCl (Ar = 1,4-phenylene), has been determined by single crystal X-ray methods. The average torsion angle o of the two ‘ether-ketone’ rings, relative to a plane defined by the bridging oxygen and carbonyl-carbon atoms is 31°. The bond angles at carbonyl-carbon and ether-oxygen are 121.9(3)° and 121.2(3)°, respectively, values which are substantially lower than those consistently reported for poly(aryletherketone)s on the basis of X-ray powder- and fibre-diffraction studies. [An average bridge-bond angle of 126.5(6)° has, for example, been proposed to account for the c-axis length of 10.09(2) A in the prototype poly(etherketone) (PEK) (-OArCOAr-)n.] Despite this apparent difference in bridge-bond angles, a PEK c-axis distance of 10.11(1) Ǎ, entirely consistent with that of the polymer, is found in the present oligomer structure. More detailed analysis of the oligomer structure reveals a pattern of sterically induced bond angle distortions at the aromatic carbon atom linked to an ether or ketone bridge, a pattern that is repeated in the X-ray structure of a second oligomer ArOArCOArArCOArOAr (Ar = phenyl or 1,4-phenylene). These findings strongly suggest that bridge-bond angles in poly(aryletherketone)s actually lie in the region of 121–122°, and that the range 125–127° consistently reported in the literature is an artifact deriving from the assumption of ideal geometry elsewhere in the polymer chain.

Formation of an unusual polymeric 24-membered macrocyclic complex of praseodymium(III): X-ray crystal structure of [Pr(Ph3PAuL)2(NO3)3]n (L = succinimide anion) and of its (Ph3P)AuL precursor

The syntheses and X-ray structures are reported of (Ph 3 P)AuL, where L = the anion of succinimide, and of the polymeric, macrocyclic array [Pr(Ph 3 PAuL) 2 (NO 3 ) 3 ] n . In the latter compound the Pr atoms are linked by succinimide anions, via Pr—O bonding, to produce sheets of fused 24-membered Pr 4 L 4 rings.

The first crystal and molecular structure of lanthanide homodinuclear macrocyclic complexes showing metal–metal pair interactions

Template condensation of 2,6-diformyl-p-cresol with 3,6-dioxa-1,8-octanediamine in the presence of lanthanide nitrates, yields homodinuclear macrocyclic complexes; solution of the structure of the gadolinium complex confirms encapsulation of a lanthanide cation pair in the macrocycle and luminescence of Eu3+ indicates Eu–Eu interactions.

Euferol and melliferol: two novel triterpenoids from Euphorbia mellifera

The structures and stereochemistries of two novel skeletons euferol [19(10→9)abeo-8α,9β,10α-tirucall-5-en-3β-ol] and melliferol [19(10→9)abeo-5α,8α,9β-tirucall-1 (10)-en-3β-ol], found in Euphorbia mellifera, have been established from spectral data and single crystal X-ray analyses.

Bridging amido complexes from reactions in liquid ammonia. X-ray crystal structure of [Pt(PMe2Ph)2(μ-NH2)2Pt(PMe2Ph)2](BF4)2

Abstract Treatment of HBF4 and a slight excess of sodium in liquid ammonia with PtCl2(PR3)2 produces [M(PR3)2(μ-NH2)2M(PR3)2](BF4)2 (2) (M = Pt, PR3 = PMe3, PMe2Ph, PMePh2, PEt3, 1/2Ph2PCH2CH2PPh2; M = Pd, PR3 = 1/2Ph2PCH2CH2PPh2) in > 80% isolated yield. The products were characterized by 31P and 1H NMR, IR and microanalysis, and in the case of PR3 = PMe2Ph (2a), by X-ray crystallography. In 2a, the cation contains a butterfly Pt2N2 ring with a dihedral angle of 32°.

Studies on transition-metal oxo and nitrido complexes. Part 11. New oxo complexes of ruthenium as aerobically assisted oxidants, and the X-ray crystal structure of [Ru2O6(py)4]·3.5H2O

The new complexes [Ru2O6L4] [L = 4-t-butylpyridine (4But-py), nicotinic acid (Hnic), isonicotinamide (isna), pyridine-2-carboxylic acid (Hpyca), or ½(2,2′-bipyridyl) (bipy)] have been prepared and the X-ray crystal structure of another member of the series, [Ru2O6(py)]·3.5H2O, determined [triclinic, space group P, a = 7.943(1), b = 8.952(2), c = 9.257(3) A, α = 98.76(2), β = 95.75(2), γ = 98.08(1)°, Z = 1, R = 0.065]. New complexes are also reported of the types trans-[RuO2L4]2+ [L = Hnic, Hpyca, or pyridine-3,4-dicarboxylic acid (H2pydca)], trans-[RuO2Cl2L2] (L = py, 4But-py or 4-chloropyridine), trans-[RuO2(pyca)2] and trans-[RuO2Cl3L]− (L = py, 4But-py, 3-methylpyridine, or 3,4-dimethylpyridine). Vibrational spectra, structures, and reactions of these species are discussed: they function as overall four-electron oxidants (eight-electron in the case of [Ru2O6L4] ), converting primary alcohols into aldehydes and secondary alcohols into ketones, and function catalytically with N-methylmorpholine N-oxide or iodosylbenzene as co-oxidant. The most soluble of them, trans-[Ru2O6(py)4]·3.5H2O, trans-[Ru2O6(4But-py)4], trans-[RuO2(py)4]2+, and trans-[RuO2Cl3(4But-py)]−, will also effect such oxidation of alcohols with dioxygen as co-oxidant.

The preparation and X-ray structures of Pt (SeSN2) (PMe2Ph)2 and [Pt(SeSN2H)(PMe2Ph)2] BF4

Abstract Reaction of [Se2SN2]2Cl2 with PtCl2(PMe2Ph)2 in liquid ammonia gives Pt(SeSN2)(PMe2Ph)2 (4), which may be protonated with HBF4 to form [Pt(SeSN2H) (PMe2Ph)2]BF4 (5); the new compounds being characterized by IR, NMR and X-ray crystallography.

Metallation of β-propiolactam; crystal structures of Hg(C3H4NO)2·H2O and of the bimetallic polymeric 48-membered macrocyclic complex [Hg3(C3H4NO)6Er2(NO3)6]n

β-Propiolactam (LH = C3H5NO) is shown to be metallated at the nitrogen atom to form the complex HgL2·H2O (1) and, in the presence of both mercury(II) and erbium(III) ions, to form a polymeric, 48-membered, puckered macrocyclic array [Hg3(L)6Er2(NO3)6]n(2).

New metal–sulphur–nitrogen compounds from reactions in liquid ammonia. The X-ray structures of trans-bis(acetophenone dimethylhydrazone-Nα)dichloropalladium(II) and [di(azathien)-1-yl-S1N4][2-(hydrazonoethyl)phenyl]palladium(II)

Reaction of [S4N3]Cl or [S3N2Cl]Cl in liquid ammonia with [PtCl2(PR3)2] or [(L–L′)PdCl2Pd(L–L′)](L–L′= C–N ligand) gives [Pt(S2N2)(PR3)2] and [Pd(S2N2H)(L–L′)] respectively; in some cases complexes containing S3N– ligands were also obtained. An alternative route to [Pd(S3N)(L–L′)] complexes using [HgPh(S7N)] is also reported. Reaction of S8–NH3(I) solutions with [PtCl2(PR3)2] gives [PtS4(PR3)2]. The new complexes were characterised by microanalyses, i.r., n.m.r., and mass spectroscopy, and X-ray crystallography.

Potential multifunctional anti-cancer metal complexes II. Synthesis of some rhodium(II) and platinum(II) complexes of diamine-substituted acridine-4-carboxamides, and the X-ray structure of [Rh(CH3CO2)2L]2 (L=N-[2-(dimethylamino)hexyl]acridine-4-carboxamide)

The preparations are reported of [Rh(RCO2)2L]2 (where R=CH3, C2H5, and CH3OCH2; L is one of a series of N-[2-(dimethylamino)alkyl]acridine-4-carboxamide ligands in which the alkyl group is ethyl, n-butyl, or n-hexyl) and also the compounds (LH)2PtCl4. X-ray structural studies have been carried out on {Rh(CH3CO2)2[N-(2-dimethylamino)hexyl]acridine-4-carboxamide}2 (1). Compound 1 is triclinic, space group P, with a=8.149(1), b=8.494(2), c=37.647(10) A, α=92.49(2), β=95.45(2), γ=91.26(2)°, V=2591 A3, Z=4 (two crystallographically independent molecules). The acridine-4-carboxamide binds to the dinuclear rhodium(II) acetate unit via the N(CH3)2 nitrogen atom with RhN bond distances of 2.339(6) and 2.349(5) A, respectively for the two crystallographically independent molecules. In common with the analogous complex formed by 6-chloro-9-(2-dimethylaminoethyl)amino-2-methoxyacridine (D M.L. Goodgame, C.J. Page and D.J. Williams, Inorg. Chim. Acta, 153 (1988) 219), the acridine units form a continuous stack in the crystal, though with different overlapping orientations. In 1 the significantly longer diamine side chain distances the acridine nitrogen atom N(10) c. 11 A from the nearest rhodium atom.