David A. Swann

Structural studies on co-ordinated macrocyclic ligands. Part III. Preparations and crystal structure analyses of salts of the nickel(II) complex C-rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane, [Ni(tetb)]2+, in the α-, β-, and γ-configurations

The preparations and X-ray structural analyses of three configurational isomers of the [Ni(tetb)]2+ complex cation are described: [Ni(α-tetb)](ClO4)2, a= 19·298(9), b= 17·34(1), c= 14·078(6)A, space group Pbca; (Ni)(β-tetb)ZnCl4,H2O, a= 19·442(8), b= 9·926(4), c= 12·657(7)A, space group Pna21: [Ni(γ-tetb)](ClO4)2, a= 17·08(2), b= 9·01(1). c= 8·19(1)A,β= 107·1(2)°, space group P21/a. The structures of the α- and β-isomer were solved from diffractometer data and of the γ-isomer from photographic data by the heavy-atom method. The structures were refined by least-squares techniques to R 0·071 (α,1 536 reflections), 0·039 (β, 1698 reflections), and 0·075 (γ, 1184 reflections). All are co-ordinatively planar and thus strained with respect to the preferred conformation attained by co-ordination of the ligand to adjacent octahedral sites. The strain induced in the macrocycle is particularly manifest in the α-isomer in the distortion of both six-membered chelate rings, in the β-isomer by the distortion of the five-membered rings, and in the γ-isomer by distortion of just one six-membered ring. Details of these deviations from preferred geometry are presented and discussed.

The chemistry of cyclopentadienyl nitrosyl compounds of molybdenum. Part 13. Hydrazine, hydrazido(1–)-, and hydrazido(2–)-complexes

Reaction of [{Mo(η-C5H5)(NO)X2}2](X = Cl, Br, or I), [Mo(η-C5H5)I(NO)(O2CMe)], or [Mo(C5H5)2I(NO)] with alkyl- or aryl-hydrazines, NHRNR′R″(R = R′= H, R″= Me, Ph, C6H4NO2-p, C6H4Me-p, or C6F5; R = H, R′= R″= Me or Et or R′= Me, R″= Ph; R = R′= R″= Me), affords (i) simple hydrazine adducts. [Mo(η-C5H5)(NHRNR′R″)(NO)X2](1), (ii) hydrazido(1–)-complexes, [Mo(η-C5H5)(NRNR′R″)l(NO)](2), and (iii) hydrazido(2–) complexes, [{Mo(η-C5H5)(NO)X}2NNR′R″](4). Protonation of (2) or (4) with HBF4 gives the hydrazine adducts [Mo(η-C5H5)I(NHRNR′R″)(NO)][BF4](3). The species (1), on the basis of spectral data, may contain either a unidentate or a chelating hydrazine, the latter forming a three- membered ring with the metal. Species (2) may also contain a three-membered MoNN chelate ring which on protonation affords (3), whose structure is known to involve a bidentate hydrazine bound to only one metal atom. The binuclear species (4) contain the hydrazido(2–)-ligand asymmetrically bridging the two Mo atoms, one N atom being bound to one Mo atom by a σ- and a (pπ→dπ)-donor bond, and the other Mo atom being attached to both N atoms viaσ bonds in a three-membered ring. The chemical and structural relationships between (1), (2), (3), and (4) are discussed.

Crystal and molecular structure of 4′-(acridin-9-ylamino)methanesulphonanilide hydrochloride, a compound showing antileukemic activity

The title compound (VI) has antileukemic properties. An X-ray analysis shows it to be triclinic, a= 14·074(1), b= 6·864(1), c= 10·166(1)A, α= 105·40(3), β= 101·60(2), γ= 86·07(3)°, Z= 2, space group P. The structure was solved by Patterson and Fourier methods. Refinement of 2070 diffractometer data reduced the R factor to 0·046. The acridine ring is slightly non-planar and the phenyl ring makes an angle of 77° with it. This latter appears to be a feature of the molecule rather than a crystal-packing requirement.

Structural studies on co-ordinated macrocyclic ligands. Part I. Crystal and molecular structure of [(1RS,3SR,8RS,10SR)-3,5,7,7,10,12,-14,14-octamethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene]nickel(II) perchlorate

The X-ray structural analysis of the title compound has been determined from diffractometer data and refined by least-squares to R 0·08 for 2211 independent reflexions. Crystals are monoclinic, space-group P21/c, a= 16·401(4), b= 10·856(6), c= 15·072(4)A,β= 91·07(3)°, Z= 4. In the complex cation the two secondary amine and two imino-donor groups are in trans planar co-ordination. The two asymmetric carbon centres and the two asymmetric nitrogen centres occur in racemic pairs, the configuration of the racemate being (1RS, 3SR, 8RS, 10SR).

Structural studies on co-ordinated macrocyclic ligands. Part II. Crystal and molecular structure of acetylacetonato-C-meso-(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane)nickel(II) perchlorate

The title compound and the corresponding cobalt(III) compound have been prepared and the crystal and molecular structure of the former has been determined fromX-ray diffractometer data. Crystals are monoclinic,a= 16·190(8), b= 12·678(7), and c= 13·197(6)A, β= 100·52(8). Space group Cc. The structure was solved by the heavy-atom method and refined to R0·0630 for 1580 independent reflections. The nickel(II) ion is in approximately octahedral co-ordination with the macrocycle folded at N(4) and N(11) to occupy four adjacent co-ordination sites, a symmetrical, planar acetylacetonato-chelate occupying the two remaining sites. In the structure the configuration of the amine is 1RS, 4RS, 7RS, 8RS, 11RS, 14SR. The five-membered chelate rings adopt unsymmetrical gauche conformations and the six-membered chelate ring including N(1) and N(11) adopts a chair conformation. That containing N(4) and N(8) adopts a twist-boat conformation which minimises non-bonded interactions of the methyl substituents. The strain inherent in this non-optimum geometry is considered to be responsible for the observed low stability of compounds in which the amine has this configuration.

Colour, isomerism, and structure of some copper co-ordination compounds. Part XXI. Crystal and molecular structure of the 2:1 adduct between 1,3,5-trinitrobenzene and bis-(N-methylsalicylaldiminato)-copper(II)

An X-ray structural analysis by the heavy-atom method of the title compound has revealed a donor–acceptor interaction between trinitrobenzene and the salicylidene residues. The monoclinic cell has dimensions a= 11·726(4), b= 9·327(2), c= 14·10(1)A, β= 93·55(5)°, Z= 2, space group P21/c. Diffractometer data (1972 observations) were refined by block-diagonal least-squares to R 0·072. The two species are arranged alternately in stacks so that each donor interacts with two acceptors and vice versa. Their molecular planes are not parallel, but make dihedral angles of 5·8 and 26·4° with one another, the interactions at ca. 3·2 A being between specific regions of each. The complex shows the familiar stepping feature and the copper atom completes a distorted but centrosymmetric octahedral stereochemistry by interaction with an oxygen atom of two symmetry related nitro-groups at 3·08 A.