Further studies on organonickel compounds: the synthesis of some new alkyl-, acyl- and cyclopentadienyl-derivatives and the crystal structure of trans-[Ni(CH2SiMe3)2(PMe3)2]

The complex [NiCl₂(PMe₃)₂] reacts with one equivalent of mg(CH₂CMe₃)Cl to yield the monoalkyl derivative trans-[Ni(CH₂CMe₃)Cl(PMe₃)₂], which can be carbonylated at room temperature and pressure to afford the acyl [Ni(COCH₂CMe₃)Cl(PMe₃)₂]. Other related alkyl and acyl complexes of composition [Ni(R)(NCS)(PMe₃)₂] (R = CH₂CMe₃, COCH₂CMe₃) and [Ni(R)(η-C₅H₅)L] (L = PMe₃, R = CH₂CMe₃, COCH₂CMe₃; L = PPh₃, R = CH₂CMe₂Ph) have been similarly prepared. Dialkyl derivatives [NiR₂(dmpe)] (R = CH₂SiMe₃, CH₂CMe₂Ph; dmpe = 1,2-bis(dimethylphosphine)ethane, Me₂PCH₂ CH₂PMe₂) have been obtained by phosphine replacement of the labile pyridine and NNN′N′-tetramethylethylenediamine ligands in the corresponding [Ni(CH₂SiMe₃)₂(py)₂] and [Ni(CH₂CMe₂Ph)₂(tmen)] complexes. A single-crystal X-ray determination carried out on the previously reported trimethylphosphine derivative [Ni(CH₂SiMe₃)₂(PMe₃)₂] shows the complex belongs to the orthorhombic space group Pbcn, with a = 14.345(4), b = 12.656(3), c = 12.815(3) Å, Z = 4 and R 0.077 for 535 independent observed reflections. The phosphine ligands occupy mutually trans positions P-Ni-P 146.9(3)° in a distorted square-planar arrangement.     

Photoinduced synthesis of the new organoseleno manganese cluster [Mn(CO)3SeC6H5]4

The synthesis of the compounds [Mn(CO)₃XC₆H₅]₄ (X = Se, S) by UV irradiation of a mixture of Mn₂(CO)₁₀ with Se₂(C₆H₅)₂ or S₂(C₆H₅)₂ is described.     

Bis(dimethylphosphino)methane (dmpm) complexes of iron,molybdenum and chromium: X-ray crystal structures of FeCr(CO)6(μ-dmpm)2 and Fe2(CO)4(μ-CO)(μ-dmpm)2

The photolysis of Fe(η¹-dmpm)(dmpm)₂ [dmpm = bis(dimethylphosphino) methane) with Cr(CO)₆ and Fe(CO)₅ under UV irradiation produces FeCr(CO)₆(μ-dmpm)₂, Fe₂(CO)₆(μ-CO)(μ-dmpm) and Fe₂(CO)₄(μ-CO)(μ-dmpm)₂ respectively. The interaction of Mo(CO)₃(MeCN)₃ and (C₇H₈)Cr(CO)₃ with dmpm produces Mo₂(CO)₆(μ-dmpm)₃ and cis-Cr(CO)₂(dmpm)₂ respectively. The X-ray crystal structure of FeCr(CO)₆(μ-dmpm)₂ shows the molecule to contain a trigonal bipyramidal Fe(CO)₃P₂ unit plus a square pyramidal Cr(CO)₃P₂ unit held closely together by the methylene bridges of the dmpm ligands with steric compression between the CO groups causing distortions from ideal geometry in each case. The Cr … Fe distance is 3.111(6) Å and there seems to be little structural evidence of any form of interaction between the 16e Cr(O) centre and the Fe-containing unit. The structure of Fe₂(CO)₄(μ-CO)(μ-dmpm)₂ contains a symmetrical μ₂-carbonyl and a single bond between the two symmetry related (m) iron atoms. The Fe … Fe distance is 2.719(4) Å.     

Mononuclear and dinuclear tertiary phosphine molybdenum complexes. oxo-molybdenum(IV), dinuclear Mo2Cl4L4 and related derivatives

Green and blue isomers of the oxo derivative MoOCl₂(PMe₃)₃ have been obtained by an oxygen-atom abstraction reaction between MoCl₄(thf)₂ and equimolar amounts of water in the presence of PMe₃. Methatesis with KX(X = NCO, NCS) yields MoOX₂(PMe₃)₃ and with NaS₂CNEt₂, MoO(S₂CNEt₂)₂(PMe₃). The latter complex readily loses PMe₃ to give MoO(S₂CNEt₂)₂ from which it can be prepared by addition of the phosphine ligand.Reaction of the blue purple complex, MoCl₃(thf)₃ (I), with excess PMe₃ gives mer-MoCl₃(PMe₃)₃ which loses PMe₃ on heating in toluene to afford [MoCl₃(PMe₃)₂]₂. Reduction of (I) with phosphines and zinc in tetrahydrofuran gives the dinuclear molybdenum(II) halide complexes Mo₂Cl₄L₄ (L = PMe₃, PEt₃, PhMe₂Ph, PEt₂Ph; L₂ = dppm), while Zn-acetic acid reduction yields Mo₂(CO₂Me)₄. Interaction of the chlorocarbonyl species MoCl₂(CO)₂(PMe₃)₃ with Tl(acac) affords Mo(acac)Cl(CO)(PMe₃)₃ which has an unusually low CO stretching frequency for a terminal carbonyl group (1755 cm^?1).     

Iron carbonyl complexes of 2,3,5,6-tetrakis(methylene)-7-oxabicyclo[2.2.1]heptane. Crystal and molecular structure of (C10H10O)Fe(CO)3 and (C9H10CO)Fe2(CO)6

The reaction of 2,3,5,6-tetrakis(methylene)-7-oxabicyclo[2.2.1]heptane (I) with iron carbonyls in various solvents yields the (η⁴-1,3-diene)Fe(CO)₃ isomers (II: exo; III: endo) and the bimetallic isomers bis[(η⁴-1,3-diene)Fe(CO)₃] (IV: bis(exo); V: endo,exo). In weakly coordinating solvents, a parallel rearrangement of I occurs through CO bond cleavage of the allylic ether by Fe₂(CO)₉ yielding an unsaturated ketone (VI) bonded to two Fe(CO)₃ groups through a trimethylenemethane and a 1,3-diene system, respectively. The geometries of III and VI have been ascertained by X-ray crystal structure determinations.     

Allyldifluorophosphite-metal chemistry: Ru complexes of F2POC3H5 and the crystal structure of (Ph3P)2(F2POC3H5)Ru(CO)(Cl)H

With several chloro ruthenium phosphine complexes, allyldifluorophosphite, F₂POC₃H₅, displaces triphenylphosphine to form new compounds in which it acts as a phosphorus donor ligand. The new complexes [PPh₃]₂[F₂POC₃H₅]Ru[CO][Cl][H], I, and [(PPh₃)₂(F₂POC₃H₅)₂RuCl₂]_nII, hav characterized by chemical, spectroscopic, and, in the case of I, crystallographic means. This behaviour of F₂POC₃H₅ contrasts to its reactions with several platinum and palladium chloro complexes where it undergoes Arbuzov-type rearrangements.     

Stereospecific functionalisations of iron carbonyl complexes of 5,6,7,8-tetrakis(methylene)bicyclo[2.2.2]oct-2-ene. Crystal and molecular structure of (C12H12)Fe2(CO)6

When the reaction between an excess of Fe₂(CO)₉ and the pentaene 5,6,7,8-tetrakis(methylene)bicyclo[2.2.2]oct-2-ene(I) is carried out in hexane/methanol the endo,exo-bis(tetrahaptotricarbonyliron) isomer (C₁₂H₁₂)Fe₂(CO)₆(IIa)is the major product. The structure of this complex has been determined by X-ray diffraction.The asymmetric positions of the two Fe(CO)₃ groups with respect to the roof-shaped organic skeleton was used to induce either stereo-specific functionalisation of the uncoordianted endocyclic CC double bond or stereo-and regiospecific functionalisation of one of the two coordinated s-cis-butadiene groups of the pentaene. Thus, hydroboration/oxidation of Ila gave the endo-exo-bis(tetrahaptotricarbonyliron)isomer of 5,6,7,8-tetrakis(methylene)bicyclo[2.2.2]octane-2-ol (IV). cis deuteration of the exocyclic double bond was achieved by treating IIa with D₂/PtO₂ in n-hexane.Protonation of IIa by HCl/AlCl₃/CH₂Cl₂ to give the η⁴-diene : η²-ene : η³-dienyl cationic complex Va, followed by quenching of Va with NaHCO₃/CH₃OH, resulted in a 1,4-addition of methanol to one coordinated s-cis-butadiene system. In contrast, quenching with NaOCH₃/CH₃OH resulted in the corresponding 1,2-addition of methanol. This gave the η⁴-1,3-diene : η⁴-1,4-diene complex VIIIa in which, suprisingly, one Fe(CO)₃ group is coordinated to two CC double bonds in gauche positions with respect to each other.     

On basic thallium sulfates: Structure of Tl2Tl OH(SO4)2

The Tl₂TlOH(SO₄)₂ compound is monoclinic, a = 7.758 (3), b = 17.587 (9), c = 7.356 (3) Å, β = 119.91 (3)°, S. G. Cc, Z = 4. The structure was solved by full-matrix least square refinement to R = 0.033 from 1242 single-crystal reflections collected on an automated diffractometer. Tl⁺ ions ensure bonding between [Tl^IIIOH(SO₄)₂]_∞ sheets. These sheets may be viewed as criss-crossing TlSO₄ chains. In the [101] direction, the linking of Tl^III is reinforced by bidentate OH groups, so the usual hexacoordination of trivalent thallium is preserved. A transition occurring at 104°C is under investigation.     

Regioselective addition of protic acids to tricarbonyliron complexes of 2,3,5,6-tetrakis(methylene)-7-oxabicyclo[2.2.1]heptane. Crystal structure of (C10H10O)Fe2(CO)6

The main product of the thermal reaction between the title oxatetraene (I) and Fe₂(CO)₉ in ether/pentane is the bimetallic complex (C₁₀H₁₀O)Fe₂(CO)₆-diexo (II), which has C_2υ symmetry both in the solid state (X-ray analysis) and in solution. Whereas the protonation of the free ligand leads usually to polymerisation, the addition of a protic acid such as CF₃CO₂H to II proceeds cleanly at 0°C giving first a (η 3-allyl)Fe(CO)₃O₂CCF₃ complex (III). The intermediate III adds a second equivalent of acid in a slower step (k₂/k₁ = 0.1, CF₃CO₂D/CHCl₃, 0°C) giving the trans-bis(η³-allyl) isomer IV with high regioselectivity. The addition of CF₃CO₂D yields the corresponding deuteriomethylallyliron tricarbonyl trifluoroacetates III′ and IV′. No further deuterium incorporation is observed at 0°C, thus confirming the kinetic control of the regioselective double addition of protic acid to II.     

Organo-imido alkoxides of tungsten(VI). The crystal and molecular structures of [W(NPh)(μ-OMe)(OMe)3]2 and [W(NPh)(OCMe3)3Cl(NH2CMe3)]

Reaction of phenylimido tungsten tetrachloride with MeOH and t-butylamine gave the dimeric complexes [W(NPh)(μ-OMe)(OMe)₃]₂ and [W(NPh)(μ-OMe)(OMe)₂Cl]₂. With ethanol [W(NPh)(μ-OEt)(OEt)₂Cl]₂ was formed whereas isopropyl and neopentyl alcohols gave the monomeric complexes [W(NPh)(OR)₄(NH₂CMe₃)](R = CHMe₂, CH₂CMe₃); t-butanol gave [W(NPh)(OCMe₃)3Cl(NH₂CMe₃)] which could not be converted to [W(NPh) (OCMe₃)₄]. Further reaction of [W(NPh)(μ-OMe)(OMe)₃]₂ with o-HOC₆H₄CH = NC₆H₃Me₂(salim-H) gave the salicylaldimine complex [W(NPh)(OMC)₃(salim)]. The products were characterised by analytical data, IR, ¹H NMR, ¹³C NMR and mass spectroscopy. The crystal and molecular structures of the title complexes have been determined from single crystal X-ray diffractometer data. Crystals of [W(NPh)(μ-OMe)(OMe)₃]₂are triclinic with a = 8.473(7), b = 10.776(5), c = 7.683(Å, α = 102.26(3), β = 102.68(4), γ = 71.13(6)°, space group P$\text{1}$ Crystals of 3) [W(NPh)(OCMe₃)₃Cl(NH₂CMe₃) are monoclinic with a = 9.341(2), b = 29.608(7), c = 10.257(2) Å, β = 106.28(2)°, space group, P2₁/c. Both structures were solved by Patterson and Fourier methods and refined to R = 0.075 for the 1022 observed data of [W(NPh) (μ-OMe)(OMe)₃]₂ and to R = 0.074. For the 2033 observed data of [W(NPh)(OCMe₃)₃Cl(NH₂CMe₃). The former molecule is shown to be a dimer, the two halves of the molecule being related by a centre of symmetry. Both W atoms adopt a distorted octahedral coordination geometry and they are linked by two methoxy bridges. Trans to one of the bridging donors is the phenyl imido group with a WN bond length of 1.61(4) Å; the remaining coordination sites are filled with methoxy groups. The structure of W(NPh)(OCMe₃)₃ Cl(NH₂CMe₃) is monomeric with the phenylimido group trans to the NH₂CMe₃ ligand in a distorted octahedral coordination geometry. Remaining sites are filled with the chloride and 3 OCMe₃ ligands. The WN (imido) bond length is 1.71(2) Å, whilst WN(amine) is 2.40(2) Å     

A dichromium(II) compound with an elongated metal-metal bond: Cr2(oxindolate)4(oxindole)2

The title compound has been prepared by reaction of (C₅H₅)₂Cr with oxindole (indole with CO in place of CH₂ at the 2-position). Red single crystals belong to space group P2₁/c with a = 10.107(4) Å, b = 22.496(7) Å, c = 9.210(3) Å, β = 93.26(3)°, V = 2091(2), and Z = 2. The centrosymmetric molecule has a CrCr distance of 2.495(4) Å. The mean CrO and CrN distances for the bonds to bridging oxindolate anions are 2.024(7) and 2.065(8) Å, respectively. There is an oxindole molecule bound at each end with a CrO axial bond of length 2.341(8) Å and a hydrogen bond from the oxindole NH group to an equatorial oxygen atom of length 2.83(1) Å. The significance of this compound with respect to CrCr bonding is discussed.     

Sign of the electric field gradient tensor and the nature of the low temperature phase transition in Fe(pyridine)2Cl2

Mossbauer spectra of Fe(pyridine)₂Cl₂ have been determined in large external magnetic fields at room temperature and 78 K. The principal component of the electric field gradient tensor is positive and consistent with an electron in the d_xy orbital. The results indicate no change in orbital ground state for the low temperature phase transition of this material.     

The molybdenum-molybdenum triple bond—XVII. Syntheses,spectroscopic and structural characterizations of Mo4F4(O—t-Bu)8 and Mo2F2(O—t-Bu)4(PMe3)2 (MoMo)

Hydrocarbon solutions of Mo₂(O—t-Bu)₆ and PF₃ (2 equiv) yield Mo₄F₄(O—t-Bu)₈, I, and PF₂(O—t-Bu). Compound I contains a bisphenoid of molybdenum atoms with two short MoMo distances, 2.26 Å, and four long MoMo distances, 3.75 Å, corresponding to localized MoMo triple bonding and non-bonding distances, respectively. The tetranuclear compound may be viewed as a dimer, [Mo₂(μ₂-F)₂(O-t-Bu)₄]₂, and addition of PMe₃ to hydrocarbon solutions of I yields Mo₂F₂(O—t-Bu)₄(PMe₃)₂, II, which contains an unbridged MoMo triple bond of distance 2.27 Å. Each molybdenum atom is coordinated to two oxygen atoms, one fluorine atom and the phosphorus atom of the PMe₃ ligand in a roughly square planar manner. The overall central Mo₂O₄F₂P₂ skeleton has C₂ symmetry and NMR studies (¹H, ¹⁹F and ³¹P) are consistent with the maintenance of this type of structure in solution. Infrared and electronic absorption spectral data are reported. These are the first compounds containing fluorine ligands attached to the (MoMo)⁶⁺ unit.     

A new monoclinic phase in the Fe2O3TiO2 system. I. Structure determination and Mössbauer spectroscopy

Single crystals with compositions within the Fe₂O₃TiO₂ system were grown from a flux containing various amounts of the basic oxides. Apart from the known pseudobrookite (Fe₂TiO₅) and rutile (TiO₂) structures, a new monoclinic polytype of Fe₂TiO₅ was found, which was isostructural with V₃O₅. The structure was determined by X-ray analysis and Mössbauer spectroscopy contributed data on hyperfine parameters and the magnetic ordering temperature.     

Synthesis of 1,2-ethanediylbis(diphenyl-phosphonium)-PH,P′H′ hexachloromolybdate(III) I and nonachlorodimolybdate(III) II. The crystal structure of (dppeH2)3[MoCl6]2·12h2O

Two compounds of the formulae (dppeH₂)₃[MOCl₆]₂ ·12H₂O I and (dppeH₂)₃[Mo₂Cl₉]₂II are described. For compound I, which proved to be active in olefin epoxidation, the crystal structure was determined. The rose-pink crystals are triclinic, space group P$\text{1}$ with a = 13.715(9), b₃ = 14.686(7), c = 12.512(7) Å, α = 109.56(4), β = 97,98(4) and γ = 91.27(5)°, V = 2345 Å, D_m = 1.42 and D_c = 1.44 gcm^?3, Z = 1. Block-diagonal least squares refinement of the structure has led to a final value of the conventional R factor of 0.049 for the 3914 independent reflections with I > 3σ(I). Bond distances are in the range: MoCl 2.439(2)–2.469(2) Å, and PC 1.771(9)–1.806(8) Å.     

Tris(difluoro and trifluorobutane-2,4-dionato) gallium(III) and indium(III) complexes

Eight tris(β-diketonate)gallium(III) and seven tris(β-diketonate)-indium(III) complexes M(RCOCH-COR′)₃, with R′being difluoromethyl and trifluoromethyl substituents and R′ being methyl, phenyl, aryl, 2′-naphthyl and 2′-thienyl substituents have been studied by nuclear magnetic resonance spectroscopy. The complexes are all nonrigid (fluxional) and their ¹⁹F NMR spectra show four resonances in the nonexchanging regions due to cis and trans isomers. A variable low temperature study of these complexes was done for the gallium chelates and activation parameters are calculated. The indium complexes all have nonexchanging regions below ?100°C. The ¹³C NMR data on the complexes are also reported.     

The preparation and X-ray structure of (disulphurdinitrido)bis(triphenylphosphine) platinum(II)—tetrachloroform solvate,Pt(S2N2)(PPh3)2·4CHCl3

Reaction of Pt(PPh₃)₃ with S₄N₄H₄ gives cis-Pt(S₂N₂)(PPh₃)₂ (1) in 45% yield. 1 was characterised be IR     

Transition-metal complexes of two valence tautomers of a bulky phenoxide, 2,6-Bu-t2-4-MeC6H2O− (ArO−); preparation and crystal and molecular structure of a phenoxytitanium(III) and a cyclohexadienonylrhodium(I) complex, [Ti(η-C5H5)2 OAr] and [Rh(ArO-η5)(PPh3)2]

The 2,6-di-t-butyl-4-methylphenoxo ligand (ArO^?) is ambidentate, giving rise to the O-bonded 15-electron d¹ [Ti(η-C₅H₅)₂OAr] and the η⁵ -[C(2)-C(6)]-bonded 18-electron d⁸ complex [Rh(ArO-η⁵)(PPh₃)₂], obtained from [{Ti(η-C₅H₅)₂Cl}₂]-LiO Ar and [Rh{N(SiMe₃)₂}(PPh₃)₂]-ArOH, respectively; the average TiC(η) distance is 2.362(10) Å, TiO 1.892(2) Å, and O:C(of Ar) 1.352(3) Å, and TiOC 142.3(2)°; in the Rh^I complex, C(2)C(6) are coplanar (with CC(av.) 1.38(2) Å). C(1)O 1.28 Å, and Rh to C(2) C(6) bond lengthsare in the range 2.19–2.65 Å.     

Vibrational and luminescence spectra of a new binuclear uranyl complex [(C2H5)4N]2[UO2F(NO3)2]2

The preparation, vibrational and luminescence spectra of the title compound are described. The complex has bidentate nitrate groups and bridging fluoride ions. The spectra are assigned in detail and interpreted as showing couplings between the uranyl antisymmetric stretching modes and between the nitrate modes within the dimer, the coupling energy being 17 cm^? in the former case. There is no clear evidence for electronic coupling involving the uranyl groups.     

Vibrational study of the unusual phase sequence in Tl3Cr(SO4)3: A compound containing [Cr(SO43−3]∞ columns

The polarized Raman spectra of small single crystals of Tl₃Cr(SO₄)₃ have been recorded using the Raman microprobe technique in the temperature range 295–660 K. The behavior of the external modes is analyzed on polycrystalline samples with conventional Raman spectrometer from 100 K to the decompositon temperature 660 K. Analysis of the spectra, in connection with dielectric measurements and X-ray data show that Tl₃Cr(SO₄)₃ undergoes the following space group phase sequence

$\text{P2}{}_1\text{c}\text{→}\text{340}\text{K}\text{R}\text{3}\text{→}\text{450}\text{K}\text{R3c}\text{→}\text{630}\text{K}\text{R}\text{3}\text{c}$

in accordance with the point group relationship

$\text{2}\text{m}\text{→}\text{3}\text{→3m→}\text{3}\text{m}$