Gallienus W. Smith

Facile synthesis of complexes of vanadium(II) and the crystal and molecular structures of hexaaquavanadium(II) trifluoromethylsulphonate

Abstract The new vanadium(II) salt [V(H2O)6](CF3SO3)2 was crystallised from solutions obtained by dissolving metallic vanadium in aqueous trifluoromethylsulphonic acid. The cations in this complex are regular octahedra (VO distance=2.119(1) A) and are extensively hydrogen-bonded to the anions throughout the lattice. The salt is soluble in several organic solvents and should be a useful starting material in the preparation of vanadium(II) complexes. Thus [V(ethylenediamine)3](CF3SO3)2 has been prepared by the addition of ethylenediamine to a solution of [V(H2O)6](CF3SO3)2 in ethanol. The preparation of [VCl2(H2O)4], [V(H2O)6]Br2 and [V(H2O)6](BF4)2 from vanadium and the appropriate aqueous acid has been confirmed.

Synthesis and structural studies of complexes of vanadium(II) and vanadium(III) halides with tertiary phosphines

Abstract The vanadium(II) halides [VCl2(H2O)4] and [V(H2O)6]Br2, prepared from the metal and the appropriate acid, combine with 1,2-bis(dimethylphosphino)ethane (dmpe) and 1,2-bis(diethylphosphino)ethane (depe) in methanol to give [VX2(dmpe)2] and [VX2(depe)2] (XCl or Br). The iodo complexes were obtained from [V(MeOH)6]I2, although [VI2(depe)2] was not pure. The complexes [VX2(dppe)2]·2thf (XCl or Br; dppe=1,2- bis(diphenylphosphino)ethane) could not be isolated from methanol, but were obtained from tetrahydrofuran (thf). All are typical vanadium(II) complexes, and [VCl2(depe)2] and [VCl2(dppe)2]·2thf have trans structures. The VCl bond distances, 2.445(2) and 2.420(1) A, respectively, are similar to that in the known complex [VCl2(dmpe)2], but the VP bond distances are longer by approximately 0.06 A and the PVP angles are smaller by c. 3°, possibly due to the steric crowding of the more heavily substituted depe and dppe ligands in the equatorial plane. Some new complexes [VX3(PR3)n] (XCl or Br, PR3=monotertiary phosphine, n=2 or 3) were also prepared from [VX3(thf)3].

Molecular structure of 1,2;3,4,di-μ,-nitrobenzoato-OO'-1,3-bis(o, m-, or p-nitrobenzoato)-l,2,4;2,3,4-di-μ3-oxotetrakis [di-n-butyltin(IV)] compounds

Abstract Infrared, Mossbauer and multinuclei ( 1 H, 13 C, 119 Sn) NMR spectral data for the title compounds and single crystal X-ray data for the ortho isomer only reveal that these compounds contain two bridging and two non-bridging (monodentate) nitro-benzoato groups. These data further confirm the existence of two six-coordinate endocyclic and two five-coordinate exocyclic tin atoms in these dimers.

Copper(II) and iron(III) complexes of N-nitroso-N- alkylhydroxylamines, and the X-ray crystal structures of bis(N-nitroso-N-isopropylhydroxylaminato)copper(II) and tris(N-nitroso-N-propylhydroxylaminato)iron(III)

Abstract N-nitroso-N-alkylhydroxylamines have been prepared by hydrolysis of the mixture obtained by reaction of nitric oxide with Grignard reagents, and stabilized as their copper(II) or iron(III) complexes, Cu(RN2O2)2 and Fe(RN2O2)3, where R is, for example, Me, Et, Pri, Buiso, Ph, n-C8H17 or n-C12H25. The complexes have been characterized by analytical, magnetic and spectroscopic measurements. By single-crystal X-ray methods Cu(PriN2O2)2 has been found to be trans-planar and Fe(PrnN2O2)3 has a facial octahedral structure; in each complex the NO bond lengths are equal with no significant variation between the copper and iron complexes.

The crystal and molecular structure of bis(1-methyl-1-phenylhydrazine)dichloro-{1-methyl-1-phenylhydrazido(2–)}vanadium(V) chloride, a complex containing two side-on-co-ordinated hydrazine molecules

The complex [VCl2(H2NNMePh)2(NNMePh)]Cl shows simultaneous co-ordination of side-on hydrazine and end-on hydrazide (2–), and forms a tetranuclear structure via an extensive array of hydrogen bonds.

The crystal and molecular structures of a tetraazaannulene and its cobalt(II) complex and the preparation of the chromium(II) complex

The structure sof the diphenyl-substituted tetraazaannulene dptaaH 2 ( 1 ) and its cobalt(II) complex Co(dptaa) ( 2 ) have been determined by X-ray diffraction. The cobalt(II) complex is low spin (μ eff = 2.5 B.M. at 291 K) and except for the two phenyl groups, which are rotated by 30.0° and 38.1° with respect to the CoN 4 plane, the molecule shows less deviation from planarity than the ligand. The chromium(II) complex is low spin(μ eff = 2.85 at 292 K and 2.72 B.M. at 87 K) and could not be obtained as a crystalline form. It is believed to be structurally analogous to Co(dptaa) and not to the related chromium(II) complex Cr 2 (tmtaa) 4 of the tetramethyldibenzotetraaza[14]annulene tmtaaH 2 , which is essentially diamagnetic and contains an unsupported quadruple bond.

Ferrocenium µ-oxo-bis[tribromoferrate(III)], a product of reaction of ferrocene with iron(III) bromide

The µ-oxo anion [(FeBr3)2O]2– has been prepared as its ferrocenium salt. The crystal and molecular structure [orthorhombic, space group Cmc2, a= 13.739(2), b= 14.721(3), c= 14.302(2)A] has been determined. The anion consists of two corner-sharing FeBr3O tetrahedra with parameters similar to those of the chloro-analogue. The cations are ferroceniums with eclipsed cyclopentadienyl rings. The magnetic susceptibility over a range of temperature is that expected for an intramolecular antiferromagnet. Both the cation and anion resonances in the Mossbauer spectrum are consistent with the structure as is the infrared spectrum. The crystal and molecular structure [orthorhombic, space group Pmcn, a= 9.036(3), b= 12.137(2), c= 14.192(2)A] of [Fe(η-C5H5)2][FeBr4] has also been determined. This consists of a perfectly tetrahedral anion and a ferrocenium with eclipsed cyclopentadienyl rings.

Some complex halides of vanadium(II) and vanadium(III). The crystal and molecular structure of tetrakis(methylammonium) hexachlorovanadate(III) chloride

Abstract Some complex chlorides of vanadium(II), A 2 [VCl 4 (CH 3 CO 2 H) 2 ], where A = NMeH 3 , C(NH 2 ) 3 (guanidinium) and C 4 H 12 N 2 (pyrazinium), have been isolated from vanadium(II) chloride in acetic acid and characterized by magnetic and spectroscopic measurements. By controlled aerial oxidation of the vanadium(II) complexes or directly from VCl 3 , a series of hexachlorovanadates (III), A 4 [VCl 6 ]Cl, has been prepared in which A = NMeH 3 , NMe 2 H 2 , NEtH 3 , NPr n H 3 and NBzH 3 . A single crystal X-ray investigation has been carried out on the methylammonium salt. There are two independent VCl 6 octahedra in the structure. Both are regular, with VCl distances in the range 2.380(2)–2.401(2) A and the internal ClVCl angles all within 0.5° of 90°. The complexes [Hpy] 3 [VCl 6 ], [NBu n H 3 ] 2 [VCl 5 ] and [NMeH 3 ] 4 [VBr 6 ]Br have also been isolated. From VCl 3 and the alkylammonium chloride in acetic acid or propionic acid as appropriate, the salts A 2 [VCl 5 (CH 3 CO 2 H)] (A = NMe 2 H 2 and A 2 [VCl 5 [C 2 H 5 CO 2 H)] (A = NPr n H 3 and NBu n H 3 ) have been obtained.

Chromium(II) complexes of o-phenylenediamine. The crystal and molecular structures of bis(o-phenylenediamine-κN)-bis(thiocyanato-κN)chromium(II) and bis(o-phenylenediamine-κ2N,N′) bis(o-phenylenediamine-κN)chromium(II) trifluoromethanesulphonate

The following chromium(II) complexes of o-phenylenediamine (opd) have been isolated: [Cr(opd)2(NCS)2], [Cr(opd)4]Br2, [Cr(opd)2I2]·1.5EtOH, [Cr(opd)Cl2], [Cr(opd)6]Cl2 and [Cr(opd)4][CF3SO3]2. From the patterns of bands assigned to NH2 and CN stretching vibrations in the infrared spectra the first two complexes contain monodentate diamine, the next two bidentate diamine and the last two both mono- and bi-dentate diamine; thus [Cr(opd)6]Cl2 is more correctly formulated as [Cr(opd)4]Cl2·2opd. Crystal-structure determinations confirm the assignments for [Cr(opd)2(NCS)2] and [Cr(opd)4][CF3SO3]2. The thiocyanato complex crystallises in the monoclinic space group P21/c with a= 11.027(3), b= 5.828(2), c= 13.431(2)A, β= 103.93(2)° and Z= 2. The structure was refined to R= 0.040 for 1551 observed reflections. There are trans-planar units in which the bond distances are Cr-NH2(monodentate diamine) 2.160(2) and Cr-NCS 2.036(2)A, with S atoms of isothiocyanato groups of adjacent units in axial positions, Cr-S 2.972(2)A forming a thiocyanato bridged structure. The triflate crystallises in the orthorhombic space group Pbca, with a= 8.978(8), b= 22.455(7), c= 16.842(2)A and Z= 4. The structure was refined to R= 0.061 for 1863 observed reflections. The co-ordination sphere consists of two bidentate diamine molecules, mean Cr-N 2.119 A, with two more distant, axially positioned, monodentate molecules at 2.669(5)A. In accordance with its structure [Cr(opd)2(NCS)2] exhibits antiferromagnetic behaviour as does [Cr(opd)Cl2] which is a chloride-bridged polymer. The triflate and the remaining complexes show simple paramagnetic behaviour (90–300 K). Attempts to prepare a chromium (II) complex of a tetraazamacrocyclic ligand by reaction of the o-phenylenediamine complexes with acetylacetone were unsuccessful; either no reaction took place or the benzodiazepinium chloride was isolated.

The synthesis and X-ray crystal structure of the monodentate (S) thiosemicarbazide and thiosemicarbazone complexes [Fe(CO)2L(η5-C5H5)][PF6]

Abstract Reaction of [Fe(CO)2(OCMe2)(η5-C5H5)][PF6] with 1 equivalent of L (L = H2NNHCSNH2 or R′R″CNNHCSNH2 where R′= R″ = Me; R′ = H, R″ = Ph; R′= H, R″ = p-NO2Ph; R′= Me, R″= p-MePh; R′R″ = C5H10) in CHCl3 at 50°C gave good yields of [Fe(CO)2L(η5-C5H5)][PF6] by displacement of the acetone. The crystal structure of [Fe(CO)2(PhCHNNHCSNH2)(η5-C5H5)][PF6] was determined by single crystal X-ray diffraction studies refined to R = 0.067 for 1389 reflections above background. The coordination geometry about the iron may best be described in terms of a “piano stool” or pseudo-octahedral structure. The C5H5− ligand occupies three sites in the octahedron with the carbonyls and the sulphur atom of the thiosemicarbazone in the other three sites. The Mossbauer isomer shifts of these compounds have values which lie between that of [Fe(CO)3(η5-C5H5)]− and those for [Fe(CO)2X(η5-C5H5)] showing the thiosemicarbazone sulphur to be a poorer π-acceptor than CO and a better π-acceptor than the halides. The similarity of the spectroscopic data for all the compounds suggests that they all have the same structure. The monodentate S-bonded nature of the thiosemicarbazide in solutions of [Fe(CO)2(NH2NHCSNH2)(η5-C5H5)][PF6] is confirmed by its reaction with benzaldehyde to give the compound [Fe(CO)2(PhCHNNHCSNH2)(η5-C5H5)][PF6].