Frederick S. Stephens

Crystal and molecular structure of chlorobis(2,2′-bipyridyl)copper(II) chloride hexahydrate

The crystal structure of the title compound has been determined by X-ray diffraction methods from three-dimensional counter data. The structure was solved by Patterson and Fourier methods and refined by least squares to R 0·064 for 1307 independent reflections. The complex crystallises in the orthorhombic space group Pnan, with dimensions a= 14·376 ± 0·027. b= 14·833 ± 0·028, c= 23·339 ± 0·061 A, and Z= 8. The cation has C2 symmetry and the environment about the copper atom is trigonal bipyramidal. The trigonal plane is formed by a nitrogen atom from each bipyridyl ligand (Cu–N 2·08 A, subtending an angle of 123° at Cu) and the chlorine atom (Cu–Cl 2·36 A). The remaining two bipyridyl nitrogen atoms occupy axial positions (Cu–N 1·98 A) and the direction between these two nitrogen atoms lies 11·5° from the normal to the trigonal plane. The cations pack in sheets perpendicular to c at z=¼ and ¾. The anionic chlorine atom and the water molecules are disordered in the channels between the cation sheets.

Crystal and molecular structure of cis-(isobutyl isocyanide)di-µ-carbonylcarbonylbis(π-cyclopentadienyl)di-iron

The crystal structure of the title compound has been determined by the heavy-atom method from X-ray diffraction counter data and refined to R 0·072 for 1447 unique reflections by a full-matrix least-squares procedure. The orthorhombic unit cell, space group P212121, has dimensions a= 6·649 ± 0·011, b= 13·062 ± 0·035, c= 20·553 ± 0·052 A, for Z= 4. The complex has a cis-configuration with a non-planar Fe(CO)2Fe bridging system, the angle between the two Fe(CO)Fe planes being 165·6°. The isocyanide ligand is terminal to one Fe, and has a linear Fe–C–N–C grouping. The distances from the iron atoms to the bridge-carbon atoms are equivalent, mean 1·91 A. The distance of the iron atom to the terminal carbonyl carbon atom is 1·745(16)A and to the isocyanide carbon atom 1·846(15)A, Fe ⋯ Fe 2·524(3)A.

Crystal and molecular structure of di-µ-carbonyl-dicarbonyl[cyclohexyl(diphenyl)phosphine](π-methylcylopentadienylnickelio)cobalt

The crystal structure of the title compound has been determined by X-ray diffraction methods using counter data. Refinement to R 0·084 for 3661 reflections was carried out by a least-squares procedure. The monoclinic unit cell, space group P21/c, has dimensions a= 14·261 ± 0·022, b= 10·034 ± 0·017, c= 18·508 ± 0·032 A, β= 98·5 ± 0·1°, for Z= 4. The dimer molecule has a non-planar Ni(CO)2Co bridging system, the angle between the two Ni(CO)Co planes being 133·9°. Metal to bridge-carbon distances are Ni–C 1·85, Co–C 1·93 A; Ni ⋯ Co is 2·418(2) and Co–P 2·269 A. The cobalt atom is in a square-based pyramidal environment. The methylcyclopentadienyl ligand and the phenyl rings are planar, and the cyclohexyl ring is in a chair conformation.

Crystal and molecular structure of di-µ-carbonyl-(tricarbonylcobaltio)carbonyl(π-cyclopentadienyl)iron

The crystal structure of the title compound has been determined by X-ray diffraction methods by use of counter data and refined to R 0·055 for 1240 unique reflections by a full-matrix least-squares procedure. The monoclinic unit cell, space group P21/m, has dimensions. a= 7·008 ± 0·009, b= 10·941 ± 0·107, c= 8·605 ± 0·016 A, β= 104·7 ± 0·1°, for Z= 2. The molecule possesses m symmetry (a requirement of the space group) and has a non-planar Fe(CO)2Co bridging system, the angle between the two Fe(CO)Co planes being 143·5°. Fe ⋯ Co is 2·545(1)A. The terminal carbonyl groups lying on the mirror plane are in a cis-configuration. The metal to bridge-carbon distances are: Fe–C 1·882(7), Co–C 2·036(7)A. The cobalt is in a square-based pyramidal environment.

Crystal and molecular structure of di-µ-carbonyl-dicarbonyl(triethyl-phosphine)cobalt(π-cyclopentadienylnickel)

The crystal structure of the title compound has been determined by X-ray diffraction methods from three-dimensional counter data. The structure was solved by Patterson and Fourier methods and refined by a least-squares procedure to R 0·052 for 2853 unique reflections. The monoclinic unit cell, space group P21/c, has dimensions a= 8·945 ± 0·008, b= 10·462 ± 0·014, c= 20·005 ± 0·025 A, β= 107·5 ± 0·1° for Z= 4. The molecule has the expected Ni(CO)2Co bridging system, the angle between the two Ni(CO)Co planes being 133·7°. Distortions within the bridging system are apparent: Ni–C(bridge) 1·825(6) and 1·900(6), Co–C(bridge) 1·956(6) and 1·890(5)A; Ni ⋯ Co is 2·4097(8) and Co–P 2·236(1)A.

Stereochemistry of the iron atom in [Fe(CO)2(η-C5H5)Y] compounds and its application to the tautomerism in bis[dicarbonyl(η-cyclopentadienyl)-iron] and related compounds

The stereochemistry of compounds of the type [Fe(CO)2(cp)Y], where cp =η-cyclopentadienyl and Y covers a range of univalent groups and includes groups which can form bridges to the iron atom, is shown to be remarkably close to a regular octahedron. The octahedral geometry does not depend on whether there are bridges present or whether Y is a ‘simple’ radical. Small deviations are discussed. By assuming that the presence of octahedral geometry in a wide range of structures indicates a certain rigidity in this arrangement, it is shown that the tautomer-interconversion mechanism for [{Fe(CO)2(cp)}2] must involve simultaneous making or breaking of two carbonyl-bridge systems. This mechanism has been suggested previously, in order to explain n.m.r. results, but has not previously been explained. A presentation is made of the general interconversion of isomers of [M(cp)M′(cp)-ABCD] where A, B, C, and D are ligands which may bridge in pairs.

Crystal and molecular structure of µ-(dichlorostannio)-bis(tricarbonyl-π-cyclopentadienylchromium)

The crystal structure of the title compound has been determined by three-dimensional X-ray diffraction methods by use of counter data and refined to R 0·057 for 3458 unique reflections by least-squares methods. The mono-clinic unit cell, space group P21/n, has dimensions a= 10·314 ± 0·012,b= 15·646 ± 0·020, c= 12·223 ± 0·012 A,β= 93·25 ± 0·1°, for Z= 4. The molecular structure consists of SnCl2 inserted into the metal–metal bond of the parent dimer [{(π-C5H5)Cr(CO)3}2]. The environment about the tin atom is distorted tetrahedral [Cr–Sn–Cr 130·2(1), Cl–Sn–Cl 95·0(1)°; mean Sn–Cr 2·697(3), Sn–Cl 2·417(4)A]. The chromium atoms have distorted octahedral environments with the carbonyl groups lying along {100} directions and the cyclopentadienyl rings lying parallel to the () faces. The Cr–Sn bonds are directed along the normals to the (11) faces of the octahedra.

Structure of an iron–cobalt organometallic complex. Crystal and molecular structure of di-µ-carbonyl-carbonyl[dicarbonyl(methyldiphenylphosphine)cobaltio]-π-cyclopentadienyliron

The crystal structure of the title compound has been determined by three-dimensional photographic X-ray diffraction methods and refined to R 0·085 for 1466 unique reflections by least-squares procedures. The triclinic unit cell, space group P, has dimensions: a= 6·948 ± 0·009, b= 11·551 ± 0·018, c= 14·618 ± 0·019 A, α= 100·9, β= 86·9, γ= 104·3°(all ±0·1°), for Z= 2. The molecule shows no overall symmetry and possesses two bridging carbonyl groups, with Fe ⋯ Co 2·540 (4)A. The Fe(CO)2Co bridging system is non-planar with the π-cyclopentadienyl ring trans to the puckering. The angle between the two bridging Fe–C–Co planes is 25·4°. The carbon atoms of the π-cyclopentadienyl ring are displaced equally from the Fe atom, mean distance 2·11 A. The Fe–C and Co–C distances in the carbonyl bridge are not equivalent: Fe–C(1) 1·797(16), Fe–C(2) 1·967(19), Co–C(1) 2·027(20), Co–C(2) 1·907(17)A, and indicate a trans-influence of the methyl(diphenyl)phosphine group. Co–P is 2·221(6)A.

Crystal and molecular structure of di-µ-carbonyl-(carbonyl-π-norbornadienecobaltio)carbonyl-π-cyclopentadienyliron

The crystal structure of the title compound was determined by X-ray diffraction methods by the heavy-atom method from counter data, and refined by least-squares techniques to R 0·063 for 3936 unique reflections. The monoclinic unit cell, space group P21/c, has dimensions a= 18·013 ± 0·027, b= 6·553 ± 0·017, c= 13·031 ± 0·037 A, β= 103·2 ± 0·1°, for Z= 4. The dimer molecule has the expected non-planar Fe(CO)2Co bridging system, the angle between the two Fe(CO)Co planes being 160·6°. The two π-bonded ligands are in a cis-configuration and the molecule as a whole has approximately m(C8) symmetry. The metal to bridge-carbon distances arc equivalent (mean 1·909 A). The environment of the cobalt is square-based pyramidal, and that of the iron octahedral; Fe ⋯ Co is 2·520(1)A.

Crystal and molecular structure of di-µ-carbonyl-carbonyl[carbonyl-(2,3-dimethylbuta-1,3-diene)cobalt]-(π-methylcyclopentadienyl)iron

The crystal structure of the title compound has been determined by X-ray diffraction methods by Patterson and Fourier methods from counter data, and refined by least squares to R 0·072 for 3066 unique reflections. The monoclinic unit cell, space group C2/c, has dimensions a= 17·700 ± 0·016, b= 7·404 ± 0·014, c= 23·861 ± 0·040 A, β= 95·5 ± 0·1°, for Z= 8. The dimer molecule has an almost planar Fe(CO)2Co bridging system; Fe ⋯ Co is 2·546(1)A. The metal–bridge-carbon distances are not equivalent [Fe–C 1·897(6) 1·916(6), Co–C 1·966(7) and 1·933(6)A]. The butadiene is in a cis-configuration and is planar. The C–C distances of the butadiene are equal, mean 1·42(1)A. The cyclopentadienyl ligand is also planar with equal C–C distances round the ring, mean 1·41(1)A.