Peter Woodward

Crystal and molecular structure of di-µ-carbonyl-cis-µ-(1–5-η: 1′–5′-η-dicyclopentadienyldimethylsilane)bis(carbonyliron)(Fe–Fe)

Crystals of the title compound are monoclinic, space group P21/n, with Z= 4 in a unit cell of dimensions: a= 11·66, b= 13·27, c= 10·82 A, β= 105° 50′. The structure was determined from diffractometer data by the symbolic addition method and refined to R 0·072 for 1309 independent reflections. The silicon atom is tetra-hedrally σ bonded to two methyl groups and to two cyclopentadienyl rings; the latter are in turn each π-bonded to one iron atom. The two iron atoms are bonded to one another (2·51 A) and are also linked by two symmetrical carbonyl bridges; the four-membered ring so defined is non-planar, being folded along the Fe–Fe axis away from the C5 rings at an angle of ca. 160°. Each iron atom also carries one terminal carbonyl group, which makes the overall co-ordination approximately octahedral.The Si atom does not lie in the Fe2(CO)2(terminal) plane, nor are the cyclopentadienyl rings symmetrically related to it (though their centroids lie in it), and the overall symmetry of the molecule is only Cs(m). Reasons for this configuration are discussed. The Fe–C and C–O distances are as expected; the four Si–C distances relatively equal, mean 1·88 A.

Crystal and molecular structure of di-µ-chloro-bis-{[1-(dicarbonyl-π-cyclopentadienylferrio)-2-phenylethyne]copper(I)}

The crystal structure of the title compound has been determined by conventional methods from the intensities of 1578 non-zero reflections measured on a diffractometer and refined to R 0·071. Crystals are monoclinic, with a= 12·57(1), b= 18·27(2), c= 7·15(1)A, β= 115·3(1)°, space group P21/a, and have two dimeric molecules per unit cell. The dimer comprises two asymmetric units related by a centre of inversion to give a central planar ring of alternating Cu and Cl atoms. The Cu–Cl distances are equivalent at 2·287(3)A and the Cu ⋯ Cu distance across the ring is 3·069(2)A. Each Cu atom is symmetrically π-bonded to the C2 unit of the phenylethynyl group [Cu–C 2·01(2)A], and the CuC2 moieties are coplanar with the Cu2Cl2 ring. The ethynyl link is 1·23(1)A, with Fe–C–C–Ph angles of ca. 162°.

Crystal and molecular structure of 1-(dicarbonyl-π-cyclopentadienylferrio)-2-(phenyl)-ethyne

Crystals of the title compound are monoclinic, a= 9·473(2), b= 9·796(2), c= 13·387(3)°A, β= 109·70(2)°, space group P21/n, Z= 4. The structure was solved by conventional methods from 1696 intensity data collected on a diffractometer and has been refined to R 0·060. The (π-C5H5)Fe(CO)2 fragment has the same geometry as in many other compounds, and the acetylenic linkage is essentially linear. There are no significant intermolecular interactions. The bond lengths of the metal ethynyl group (Fe–C 1·91, –CC– 1·21, and C–Ph 1·44 A) provide a useful comparison with those in other acetylenes.

Crystal and molecular structure of bis-(π-2-methylallyl)bis(trimethyl phosphite)ruthenium. An example of asymmetric π-bonding between methylallyl ligands and ruthenium

The crystal structure and molecular stereochemistry of the title compound have been determined from three-dimensional X-ray diffraction counter data by Patterson and Fourier methods. Crystals are monoclinic, a= 15·12, b= 17·86, c= 8·10 A, β= 113·4°, space group P21/a, Z= 4. The structure has been refined by least-squares methods to R 0·051 for 677 independent reflections. The ruthenium atom is octahedrally co-ordinated and has the trimethyl phosphite ligands mutually cis; the methylallyl groups each occupy two adjacent sites. The bonding of each methylallyl group to the ruthenium atom is asymmetric: mean Ru–C(trans to P) 2·38(2); mean Ru–C(trans to C) 2·18(2)A. The methylallyl groups are non-planar, the methyl group being bent out of the plane of the allyl moiety by some 12° away from the metal. The allyl plane is almost exactly perpendicular to the plane defined by the two outer carbon atoms and the ruthenium atom.

Crystal and molecular structure of di-µ-dimethylstannylene-bis(carbonyl-π-cyclopentadienylcobalt): a metal ring compound

Crystals of the title compound are triclinic, space group P, with Z= 2 in a unit cell of dimensions a= 11·23(2), b= 11·10(2), c= 7·82(1)A, α= 95·7(2). β= 97·0(2), γ= 89·1(2)°. The structure was refined to R 0·085 for 1520 independent reflections measured on a diffractometer. There are two crystallographically distinct molecules in the unit cell, each located astride a centre of inversion; they show no significant differences in their molecular geometry but are differently oriented in the unit cell. Sn and Co atoms alternate around a planar four membered ring, the Sn atoms having only slightly distorted tetrahedral co-ordination, and Co having octahedral co-ordination if the cyclopentadienyl ring is assumed to occupy three sites. The idealised molecular symmetry is C2h(2/m), with the two-fold axis through the Sn atoms and the mirror through the Co atoms, the CO groups, and bisecting the cyclopentadienyl rings which lie mutually trans across the plane of the metal-atom ring. In the C5 ring, the carbon atom in the mirror plane is also diametrically opposite to the CO group attached to the same Co atom. Co–Sn [2·542(2)A] is significantly shorter than expected, but Co–C(CO), Co–C(π-C5H5), and C–O are ‘normal’; Sn–Co–Sn is 78°. The carbonyl groups occupy trans‘axial’ positions and are inclined slightly inwards; mean Sn–C 2·20(1)A, C–Sn–C only a little less than the tetrahedral value.

Pentalene complexes from cyclo-octatetraenes: crystal structure of Ru3(CO)8(C8H6)

Cyclo-octatetraenes R-C8H7(R = H, Me, Ph) undergo transannular cyclisation on reaction with Ru3(CO)12 in refluxing heptane or octane to form pentalene complexes Ru3(CO)8(R-C8H5); the molecular structure of fluxional Ru3(CO)8(C8H6) has been determined by an X-ray diffraction study.

Crystal and molecular structure of 4-[(diethylamino)(t-butylamino)methylene]-4-(t-butyl isocyanide)-2,2,5,5-tetrakis(trifluoromethyl)-1,3,4-dioxapalladolan: a palladium(II) carbene complex

Crystals of the title compound (I) are monoclinic, space group P21/a, with Z= 4 in a unit cell of dimensions: a= 20·093(3), b= 9·519(2), c= 15·201(3)A, β= 96·77(2)°. The structure has been elucidated by conventional heavy-atom methods from 4123 diffracted intensities measured on a four-circle diffractometer, and refined to R 0·099. The palladium atom, which is in an approximately square-planar environment, forms part of a five-membered condensed hexafluoroacetone ring, [graphic omitted], which is of envelope conformation. The O–C(CF3)2 bond from the oxygen atom adjacent to the metal in this ring is notably short [1·337(13)A]. The plane of the carbene ligand lies perpendicular to the co-ordination plane of the Pd atom; there is virtually no back-donation from Pd to carbene [Pd–C(4) 2·07 A], and the carbene lies trans to C(1) of the five-membered ring. The C–N bond distances within the carbenoid fragment (mean 1·32 A) indicate a high degree of delocalisation. The short intramolecular contact between the H atom of the NHBut group and one of the methylene hydrogen atoms of the NEt2 group supports spectroscopic evidence for restricted rotation around an N–Et bond.

Crystal and molecular structure of cis-fluoro-(1,1,1,3,3,3-hexafluoroisopropyl)bis(triphenylphosphine)platinum, PtF[CH(CF3)2](PPh3)2: a square planar metal fluoro-complex

Crystals of the title compound are monoclinic, space group P21/a, with Z= 4 in a unit cell of dimensions: a= 18·690(5), b= 18·662(18), c= 9·897(15)A, β= 94·7(1)°. The structure was solved by conventional heavy-atom methods and refined by least squares to R 0·063 for 1937 independent reflections measured on a diffractometer. The platinum atom is in a square planar configuration. Two adjacent sites are occupied by triphenylphosphine groups, the other two by fluorine and a hexafluoroisopropyl group. The two Pt–P distances are significantly different; that trans to fluorine is 2·218(7), while that trans to –CH(CF3)2 is 2·310(7)A. The geometry of the ligands is as expected.

Bridging cycloheptatrienyl complexes: X-ray crystal structure of [Ru2(CO)5(SiMe3)(C7H6SiMe3)]

Cycloheptatrienes, 7-RC7H7, react with [Ru(CO)4(SiMe3)]2 to afford inter alia fluxional complexes [Ru2(CO)5(SiMe3)(C7H6R)](R = H, Me, Ph, C6F5); an X-ray structural study on a minor product form C7H8 reveals ring substitution by a trimethylsilyl group.