Manuel Font-Altaba

Ligand exchange reactions in cyclopalladated complexes of benzylideneanilines. Crystal structure of [Pd(C6H4CHNC6H5)Br(PPh3)2]

The ligand exchange reactions between [{[graphics omitted]C6H5)(O2CMe)}2] and the free imines p-RC6H4CHNC6H5(R = H, Cl, NMe2, or NO2)(N[graphics omitted]CH) in acetic acid have been studied. The substitution process is favoured when the incoming ligand contains electron-withdrawing substituents. From the results obtained a new mechanism involving a bis-cyclometallated complex ([graphics omitted]P[graphics omitted])] as intermediate is proposed. The dimeric cyclopalladated compounds are obtained by metallation of the imines by Pd(O2CMe)2; by reaction with phosphines PR′3 and LiBr, [[graphics omitted]C6H5)Br(PR′3)] and [Pd(p-RC6H3CHNC6H5)Br(PR3′)2] are formed (R′= Ph or Et). All the compounds have been fully characterized and their 1H and 13C n.m.r. spectroscopic data recorded. The molecular structure of [Pd(C6H4CHNC6H5)Br(PPh3)2] has been determined by a single-crystal X-ray analysis. The crystals are monoclinic, space group P21/a, a= 17.427(3), b= 24.790(4), c= 10.424(2)A, β= 98.91(2)°, and Z= 4; R= 0.053 for 6 579 reflections. The palladium atoms are five-co-ordinated, the Pd–N distance being 2.710(6)A.

Electrochemical, EPR, and crystal structure studies on mixed-ligand 4,5-dimercapto-l,3-dithia-2-thione phosphine complexes of nickel, palladium and platinum, M(dmit)(dppe) and Pt(dmit)(PPh3)2

Complexes of the type M(dmit)(Phos)2 (M = Ni, Pd, Pt; Hsdmit = 4,5-dimercapto-1,3-dithia-2-thione; (Phos)s = dppe = 1,2-bis-diphenylphosphinoethane. M = Pt; (Phos)s = (PPha),) have been studied by means of X-ray diffraction method, and electrochemical techniques coupled with EPR spectroscopy. The crystal structure of Pt(dmit)(dppe) has been determined: this compound crystallizes in the monoclinic space group P2r/n witha = 18.267(3), b = 16.903(3), c = 9.748(2) A, fl= 95.50(2)” and 2 = 4. The environment of the platinum atom is nearly square-planar (Pt-P = 2.254(3), I’-S = 2.3 1 l(3) A) with very slight tetrahedral distortion. The cyclic voltammetry parameters for the oxidation and the reduction of the studied complexes have been determined in CHzClz: Ni(dmit)(dppe) undergoes a quasi-reversible one-electron reduction step. Pd(dmit)(dppe) undergoes an irreversible two-electron reduction step. Both Pt(dmit)(dppe) and Pt(dmit)(PPhs)s do not undergo reduction. All three M(dmit)(dppe) (M = Ni, Pd, Pt) undergo a reversible one-electron oxidation step, the Pt(dmit)(PPh& a quasi-reversible one. EPR studies of the electrogenerated complexes show that the reduction of Ni(dmit)(dppe) is metal-based and that the [Ni(dmit)(dppe)]- is a nickel(I) species. The oxidation of the M(dmit)(dppe) complexes is ligand-based and the unpaired electron in the [M(dmit)dppe]+ species is mainly delocalized on the dmit ligand. plexes may be used as molecular model systems of metal-tetrathiolato polymers (MC2S4), [4,5]. These polymers have aroused great interest because of their high compaction powder conductivity (up to 50 s2-’ cm-’ [6,7]). They have been the subject of several research works including their transport properties and degree of partial oxidation [5,8], magnetic behavior [5,9] and formation mechanism [4-71. The formation mechanism of these polymers that we have proposed [5] was based upon the unexpected obtaining of mononuclear metal complexes, M(dmdto)(Phos)2 and M(dmit)(Phos)? ((Phos)2 = dppe = 1,2-bis-diphenylphosphinoethane; (Phos)s = (PPhs)2; H2dmdto = 4,5-dimercapto-1,3-dithia-2one). These complexes were characterized by elemental analysis, IR spectra and mass spectra [4], but none of the crystal structures had been determined. We report here the crystal structure of one member of these series, Pt(dmit)(dppe).

Synthesis and structure of chloro(ligand)bis(diphenylglyoximato)cobalt(III) complexes

Abstract The synthesis and characterization of trans-chloro- (ligand)bis(diphenylglyoximato)cobalt(III) complexes [ligand = pyridine (py), α-, β-, or γ-picoline (α-pic, β-pic, γ-pic), 3,5-lutidine (lut), p-toluidine (p-tol) and PPh3] is presented. X-ray crystal structure determination of the pyridine (1) and p-toluidine (6) derivatives has been carried out. Compound 1 crystallizes in the monoclinic system, space group P21/n, with Z = 4 and unit cell parameters a = 23.124(4), b = 13.009(3) and c = 11.204(3) A, and β= 93.14(2)°. Compound 6 crystallizes in the monoclinic system, space group P21/n, with Z = 4 and unit cell parameters a = 18.792(3), b = 12.540(2) and c = 15.346(3) A, and β = 97.54(2)°.

Gold(I) and gold(III) ortho-nitrophenyl complexes. Crystal and molecular structure of ortho-nitrophenyltriphenylarsinegold(I)

Abstract The reaction between [Au(o-C6H4NO2)Cl]− and tetrahydrothiophene (tht) in the presence of NaClO4 give a solution (probably containing [Au(o-C6H4NO2)(tht)]) that can be used to prepare neutral [Au(o-C6H4NO2)Ln] (L = AsPh3, n = 1; L = SbPh3, n = 2; L = 1,10-phenanthroline, n = 1) or anionic [Au(o-C6H4-NO2(CN)]− complexes. Treatment of [Au(o-C6H4NO2)(PPh3)] with chlorine or PhICl2 gives trans- or cis-[Au(o-C6H4NO2)Cl2(PPh3)]. Isomerizations occur when the cis-isomer is treated with concentrated solutions of chlorine or when the trans-isomer is heated. An X-ray diffraction study of [Au(o-C6H4NO2)(AsPh3)] has revealed an almost linear coordination around the gold atom (AsAuC mean value 177(2)°). The AuO distance is too long (mean value 2.80(3) A) for intramolecular coordination.

o-Nitrophenylpalladium(II) complexes. Crystal and molecular structures of cis-[Pd{o-C6H4N(O)O}2] and cis-[Pd{o-C6H4N(O)O}(o-C6H4NO2)(py)]

Bis(o-nitrophenyl)mercury reacts with palladium dichloride in molar ratios of 2 : 1 or 1 : 1 to give cis-[[graphic omitted]}2] or [{[graphic omitted]](µ-Cl)}2], respectively. The first product reacts with some unidentate (L) or bidentate (L–L) ligands to give [[graphic omitted]}(o-C6H4NO2)L][L = Ph3PCHCO2Me, pyridine (py), 3-bromopyridine, or 4-cyanopyridine] or [Pd(o-C6H4NO2)2-(L–L)][L–L = 1, 10-phenanthroline, 2,2′-bipyridine, 1,2-bis(diphenylphosphino)ethane, or bis-(diphenylphosphino)methane] or with PdCl2, Cl2, PhlCl2, or HgX2 to give [{[graphic omitted]]-(µ-X)}2](X = Cl or Br). The chloro complex reacts (i) with unidentate ligands L (molar ratio 1 : 2) to give [{Pd(o-C6H4NO2)L(µ-Cl)}2](L = PPh3 or AsPh3), (ii) with cyclo-octa-1,5-diene (cod) to give [Pd(o-C6H4NO2)Cl(cod)], and (iii) with thallium acetylacetonate, Tl(acac), to give [[graphic omitted]}(acac)]. The crystal structure of cis-[[graphic omitted]}2] consists of molecules, with square-planer co-ordination, stacked parallel to the (001) plane with alternate Pd ⋯ Pd distances of 3.465(1) and 3.209(1)A. The Pd–C [2.033(5)A(av.)] and Pd–O [2.144(14)A(av.)] bond lengths are normal, while the C–N [1.390(4)A(av.)] are shorter than those found in unidentate nitroaryl ligands. The structure of [[graphic omitted]}(o-C6H4NO2)-(py)] shows a square-planar co-ordination around the palladium atom with a cis configuration of the phenyl groups. The only significant differences between both types of o-nitrophenyl ligands are shorter C–N [1.428(6)A] and longer N–O(Pd)[1.265(5)A] bond distances in the chelating than in the unidentate ligand [1.464(5) and 1.222(5)(av.)A, respectively].

Bis[2-(phenylazo)phenyl-C1N′]gold(III) complexes. Crystal and molecular structure of bis[2-(phenylazo)phenyl-C1N′]gold(III) tetrachloroaurate

The reaction between [NMe4][AuCl4] and [Hg(pap)2][pap = 2-(phenylazo)phenyl] gave the gold(III) complex [Au(pap)2Cl] which reacts with AgClO4 to form [Au(pap)2]ClO4. Addition of [PPh3(CH2Ph)]X (X = Cl), NaX (X = Br), or KX (X = l, CN, or O2CMe), to the cationic complex leads to the corresponding neutral complexes [Au(pap)2X]. Reaction of [Au(pap)2]ClO4 with [NMe4][AuCl4], leads to [Au(pap)2][AuCl4]. By reacting the neutral acetato-complex with [Hpy]ClO4(Hpy = pyridinium), [Au(pap)2(py)]ClO4 is prepared. The crystal structure of [Au(pap)2][AuCl4] has been determined and shows that the cation has a square-planar co-ordination with two cis-nitrogen [Au–N = 2.17(2)A(av.)] and two cis-carbon [Au–C = 2.00(2)A(av.)] atoms bonded to gold.

Reaction of di-t-butoxyethyne with Fe2(CO)9: X-ray crystal structure of (tetra-t-butoxycyclopentadienone)tricarbonyliron (0) and an improved formal synthesis of hydrocroconic acid and the croconate dianion

Di-t-butoxyethyne (1a) reacts with [Fe2(CO)9] affording (tetra-t-butoxycyclopentadienone)tricarbonyliron(0)(5a), the crystal structure of which has been determined by X-ray diffraction. Treatment of (5a) with trimethylamine oxide affords tetra-t-butoxycyclopentadienone (8), which had been previously converted into hydrocroconic acid (2) and the croconate dianion (3). On the other hand, (5a) with trifluoroacetic acid affords (tetra hydroxycyclopentadienone) tricarbonyliron (0)(5b), which is converted into the croconate dianion (3) by oxidation with molecular oxygen in basic medium.

Synthesis and structure of chloro(ligand)bis(glyoximato)cobalt(III) complexes: structural evidence of an electronic effect on the structure of the dimethylpyrazine ligand

Abstract The synthesis and characterization of trans-chloroligandbis(glyoximato)cobalt(III) complexes (ligand=2,6-dimethylpyrazine, β-picoline and γ-picoline) are presented. X-ray crystal structure determination of the dimethylpyrazine derivative, [CoCl(gH)2(Me2pz)] (1), has been carried out, and two important structural features found: a significant change in bond distances within the aromatic nitrogen donor upon substitution of a methyl group of the equatorial dioximato ligand by a hydrogen, and a conformational preference for the axial ligand which appears to be oriented parallel to the equatorial CC bonds, indicating that the substituents of the dioximato ligand are not important in determining that conformation. Changes in the bond angles of the glyoxime ligands upon coordination are due to chelation and hydrogen bond formation. Compound 1 is monoclinic, space group P21/n, with Z=4 and unit cell parameters a=14.973(3), b=10.790(2) and c=10.844(2) A and β=90.92(2)°.

Metal complexes of anxiolitic drugs. X-Ray crystal structure and electronic properties of aquobromazepam(oxalato O1 O2) copper(II)

SummaryThe crystal structure of the title compound has been determined from single-crystal x-ray diffraction data. The copper(II) ion is surrounded by two nitrogen atoms of the bromazepam** molecule [N(imine) and N(pyridine)], and two oxygen atoms of the oxalate ion in a square planar arrangement. One molecule of water is linked to the copper(II) ion in the axial position. The complex has been also characterized by electronic, e.s.r. and i.r. spectra.

Synthesis, crystal structure and properties of [Fe(h5-C5H5)(CO)(μ-SC5H9NCH3)]2

Summary The reaction of Fe 2 (CO) 4 ( h 5 -C 5 H 5 ) 2 with 4- N -methylpiperidine-disulphide affords [Fe( h 5 -C 5 H 5 )(μ-SC 5 H 9 NCH 3 ] 2 , the crystal structure of which has been determined. The crystals are monoclinic, space group C2/c with a 18.761(3), b 14.543(2), c 9.556(1)A, β 103.67(2)°. With Z = 4 the calculated density is 1.46 g cm cm −3 ; the final weighted R factor was 0.047 for 1645 independent reflections. The two carbonyl groups and the two sulphur-attached piperidine groups in the dimeric structure are both cisoid. Reaction with CH 3 I leads to methylation that with aqueous HClO 4 to protonation of the nitrogen atoms of the piperidine rings, giving formation of the [Fe( h 5 - C 5 H 5 )(CO)(μ-SC 5 H 9 N(CH 3 ) 2 ] 2 I 2 · 2H 2 O salt and [Fe( h 5 -C 5 H 5 )(CO)(μ-SC 5 - H 9 NHCH 3 )] 2 2+ cation, respectively.