Reactions of collman complex with tin(IV) and germanium(IV) porphyris,formation of [tin(II) and germanium(II) porphyrins] tetracarbonyliron and crystal structure of [2,3,7,8,12,13,17,18-octaethylporphinato tin(II)] tetracarbonyliron

The action of Na₂Fe(CO)₄ with tin(IV) and germanium(IV) porphyrins affords metal(II) porphyrin complexes [(por)M(II)Fe(CO)₄] (por = porphyrinate, M - Sn(II) or Ge(II)). The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques. The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques : the Sn coordination is square pyramidal with the iron in axial position (Sn-Fe = 2.492(1)Å) whereas the Fe coordination is trigonal bipyramidal. Mössbauer parameters provide convincing evidence for the formal zero oxidation state of the iron atom.     

Structure elucidation of dicarboxylate complex of Sn porphyrin with a ring current effect model

A new simple model of porphyrin ring current effect was proposed based on a line current approximation. It can reproduce the porphyrin-induced shifts for several Sn(IV)(tpp) and Sn(IV)(oep) dicarboxylate complexes quite satisfactorily. Perpendicular arrangement of the aromatic rings in the diaromatic-carboxylate complexes of Sn(IV)(tpp) and Sn(IV)(oep) was clarified with this porphyrin ring current effect model. There are two structures, exo and endo, in solution in dinaphthalene-1- and 2- carboxylate complexes of Sn(IV)(tpp) and Sn(IV)(oep). The exo conformer is in dynamic equilibrium with the endo form in solution. Thermodynamic data of these conformational equilibria are given.     

Vanadium (IV) porphyrins: synthesis and spectro-chemical characterization of thiovanadyl porphyrins. Exafs structural study of thio (2, 3, 7, 8, 12, 13, 17, 18 - octaethylporphyrinato) vanadium (IV).

The action of elemental sulfur with vanadium (II) porphyrins complexes [V^II(por)(THF)₂] (por = porphyrinate) affords the thiovanadyl porphyrins [V^IV(por)(S)]. EXAFS spectroscopy at the V K-edge of [V^IV(oep)(S)] confirms the axial symmetry of these complexes.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

Preparation and characterization of heterobimetallic tetraxanthates and their complexes with Lewis bases

Some new heterobimetallic tetraxanthates of the type M[Ag(Etxant)₂]₂ [M = Co(II) or Ni(II), Etxant = ethylxanthate] and their complexes of general formula M[Ag(Etxant)₂]₂.xL [x = 2 when L= dimethylsulphoxide (DMSO), triphenylphosphine (Pph₃), pyridine(py) or 2-aminopyridine (2-ampy); x = 3 when L = 2,2′-bipyridine (bipy)] have been prepared and characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. Magnetic and electronic spectral studies indicate square planar geometry around Ni(II) and Co(II) in heterobimetallic tetraxanthates and Ni[Ag(Etxant)₂]₂.2PPh₃ and octahedral geometry around the above metal ions in the remaining complexes.     

Tris(mercaptoimidazolyl)hydroborato complexes of cobalt and iron, [TmPh]2M (M=Fe,Co): structural comparisons with their tris(pyrazolyl)hydroborato counterparts

The tris(mercaptophenylimidazolyl)borate iron and cobalt complexes [Tm^Ph]₂M (M=Fe, Co) have been synthesized by reaction of [Tm^Ph]Tl with MI₂. Structural characterization by X-ray diffraction demonstrates that the potentially tridentate [Tm^Ph] ligand binds through only two sulfur donors in these ‘sandwich’ complexes and that the ‘tetrahedral’ metal centers supplement the bonding by interactions with the two B–H groups. Comparison of the structures of [Tm^Ph]₂M (M=Fe, Co) with the related tris(pyrazolyl)borate [Tp^Ph]₂M counterparts indicates that the tris(mercaptoimidazolyl) ligand favors lower primary coordination numbers in divalent metal complexes. The trivalent complexes, {[Tp^Ph]₂Fe}[ClO₄] and {[pzBm^Me]₂Co}I, however, exhibit octahedral coordination, with the ligands binding using their full complement of donor atoms.     

Di-η5-cyclopentadienylmetal complexes with nitrogen donor atom ligands: New imidazole, N-methylimidazole,pyrazole and 2,2′-bisimidazole complexes of molybdenum and tungsten

Reactions of the tetrahedral metallocene derivatives [M(η-C₅H₅)₂X₂], [M(η-C₅H₅)₂HX] and [M(η-C₅H₅)₂H₃][PF₆] (M = Mo, W; X = halogen) with ligands imidazole, N-methylimidazole, pyrazole and 2,2′-bisimidazole give a wide range of new mono- and bi-nuclear complexes. The pK_a values for some of the coordinated ligands and the ESR spectra of some molybdenum(V) complexes obtained by oxidation of their molybdenum(IV) analogues are also presented and discussed.     

Zur chemie des tris(cyclopentadienyl)uran(IV)-kations in wässriger lösung : II. Oligomere metallorganische tetracyanometallat-komplexe des uran(IV): Bis(tris(pentahapto-cyclopentadienyl)uran(IV))-tetracyanonickolat(II) bzw. -platinat(II)

Novel organometallic uranium(IV) complexes of the composition [(η⁵-Cp)₃U^IV]₂[Mn^II(CN)₄] Cp = C₅H₅, M = Ni or Pt) have been prepared from Cp₃UCl and K₂[M(CN)₄] in aqueous solution. On the basis of their properties they are characterized as layered oligomeric structures involving squared arrays of both the U and M atoms within the same plane, and a presumably trigonal bipyramidal coordination of the uranium(IV) ion.     

Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles

Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double‐decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [Tb^III(tpp)₂]ⁿ (tpp: tetraphenylporphyrinato, n=?1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [Tb^III(oep)₂]^?1 and [Tb^III(oep)₂]⁰ (oep: octaethylporphyrinato), but φ=36° for [Tb^III(oep)₂]⁺¹. Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system.     

Complexes du titane et du zirconium contenant les ligands cyclopentadienyldiphenylphosphine et cyclopentadienylethyldiphenylphosphine: acces a des structures heterobimetalliques

Reactions of Ph₂P(CH₂)_n(C₅H₄)Li, (n = 0, 2), with MCl₄ or CpTiCl₃ (M = Ti, Zr; Cp = η⁵-C₅H₅) form Cl₂M[(η⁵-C₅H₄)(CH₂)_nPPh₂]₂ or Cl₂CpTi[(η⁵-C₅H₄)-(CH₂)₂PPh₂] in good yields. Chemical reduction with Al, or electrochemical reduction of these complexes, under CO, are described. The titanium(IV) and zirconium(IV) derivatives react with metal carbonyls (Mo(CO)₆, Cr(CO)₆, Fe(CO)₅, Mo(CO)₄(C₈H₁₂)) under formation of new heterobimetallic complexes. Reduction with Al of Cl₂CpTi[(η⁵-C₅H₄)(CH₂)₂PPh₂]Mo(CO)₅ under CO results in a new heterobimetallic species containing low valent titanium. Both complexes Cl₂M[(η⁵-C₅H₄)(CH₂)₂PPh₂]₂ (M = Ti, Zr) react with [Rh(μ-Cl)(CO)(C₂H₄)]₂ to yield {RhCl(CO)(Cl₂M[(η⁵-C₅H₄)(CH₂)₂PPh₂]₂)}x, which is assumed to be a dimer, in which the titanium or the zirconium compounds act as bridging diphosphine ligands between the rhodium atoms.     

Formal Co(0), Fe(0), and Mn(0) complexes with NHC and styrene ligation

The limited knowledge on low-coordinate zero-valent transition-metal species has intrigued great synthetic efforts in developing ligand sets for their stabilization. While the combined ligand set of N-heterocyclic carbene (NHC) with vinylsilanes was the only known ligand system amenable to the stabilization of three-coordinate formal zero-valent cobalt, iron, and manganese complexes, the exploration on other ligands has proved that the ligand set of NHCs with styrene is equally effective in stabilizing three-coordinate formal zero-valent metal complexes in the form of (NHC)M(η²-CH₂CHPh)₂ (NHC = IPr, IMes; M = Co, Fe, Mn). These styrene complexes can be prepared by the one-pot reactions of MCl₂ with styrene, NHC and KC₈, and have been characterized by various spectroscopic methods. Preliminary reactivity study indicated that the interaction of [(IMes)Fe(η²-CH₂CHPh)₂] with DippN₃ produces the iron(IV) bisimido complex [(IMes)Fe(NDipp)₂] and styrene, which hints at the utility of these zero-valent metal styene complexes as synthons of the mono-coordinate species (NHC)M(0).     

The infrared spectra of ethylenediamine complexes—II. Tris-, bis- and mono(ethylenediamine) complexes of metal(II) halides

The i.r. spectra of the complexes M(en)₃X₂ (M = Mn, Fe, Co, Ni, Cu, Zn), trans-Cu(en)₂X₂, Ni(en)₂X₂ and M(en)X₂ (M = Ni, Cu, Zn; X = Cl, Br, I) have been studied. Assignments are proposed for the tris(ethylenediamine) complexes on the basis of ¹⁵N-, N₂D₄- and C₂D₄-labelling of en and the effects of metal ion substitution in relation to our earlier study of [M(en)₃]SO₄ complexes. Assignments for the bis(ethylenediamine) complexes are based on our observations of halogen-sensitivity and earlier studies on metal isotope labelling and ligand deuteration of the halide complexes and a normal coordinate analysis of the [Cu(en)₂]²⁺ species. The spectra of the halide complexes have been extended below 200 cm⁻¹ for the first time. Finally, the spectra of the mono(ethylenediamine) complexes are discussed in relation to their known or probable structures.     

The far-infrared spectra of pyridine complexes of transition metal(II) isothiocyanates

The infrared spectra (500–140 cm^?1) of the complexes [M(pyridine)_n(NCS)₂] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v/M-pyridine and v/M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine)₂Cl₂] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of vM-pyridine bands require revision. The spectra of the yellow [Fe(py)₄(NCS)₂] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans-[Fe(py)₄(NCS)₂] into cis-[Fe(py)₃(NCS)₃]     

The formation of alkyne and alkynyl complexes by reaction of 1-alkynes with trans-[M(N2)2(PH2PCH2CH2PPh2)2] (M  Mo OR W) and with [Mo(Ph2PCH2PPh2)3]: X-ray structure of trans-[Mo(CCPh)2(PH2PCH2CH2PPh2)2]

Reaction of RCCH (R  Ph, CO₂Meor CO₂Et) with trans-[M(N₂)₂(dppe)₂] (M  Mo or W; dppe  Ph₂PCH₂CH₂PPh₂) or [Mo(dppm)₃] (dppm  Ph₂PCH₂PPh₂) gives the alkyne complexes [M(RCCH)₂(diphos)₂] (diphos  dppe, M  Mo, R = Ph; dihpos  dppm, M  Mo, R  Ph or CO₂Me) and the alkynyl complexes trans-[M(cCR)₂(dppe)₂], [MH₂(CCR)₂ (dppe)₂] (M  Mo or W. R  Ph, CO₂Me or CO₂Et) and cis-[WH(CCCO₂Me)(dppe)₂]: the X-ray structure of trans-[Mo(CCPh)₂(dppe)₂] is reported.     

Cyclohexylethynyl complexes of CoII and FeII

This paper deals with the synthesis of six σ-cyclohexylethynyl complexes of Co^II and Fe^II and their characterization by chemical analysis, infrared and ¹H NMR spectra, and magnetic measurements. Four of them are six-coordinate complexes, unsubstituted or substituted, namely K₄[M(C≡C—C₆H₁₁)₆] nNH₃(M = Co, n = 2; M = Fe, n = 0), K₂[Co(C≡C₆H₁₁)₄(NH₃)₂] and K₄[Fe(CN)₄-(C≡C—C₆H₁₁)₂]. Two are four-coordinate complexes of formula [(Ph₃P)₂M-(C≡C₆H₁₁)₂] (M = Co, Fe). All are low-spin complexes, the magnetic moment for the six-coordinate Co(II) complexes, measured at various temperatures, being intermediate between low- and high-spin values.     

The bidentate behaviour of tetrahydroborate towards copper(II) and group(IV) metals in heterobimetallic complexes

Summary New heterobimetallic complexes of the type [Cu(TETA)-BH₄)₂M(BH₄)₂] (TETA = triethylene tetramine; M = Si, Ge, Sn, Ti and Zr) were prepared by the interaction of [Cu(TETA)Cl₂MCl₂] with an excess of KBH₄ in THF. The results indicate that the complexes are nonelectrolytes and the tetrahydroborate group links to the copper(II) atom and the group(IV) metal in a bidentate manner adopting C _2v symmetry.     

Double complex salts [M(NH3)5Cl][M′Br4] (M = Rh, Ir, Co, Cr, Ru; M′ = Pt, Pd): Synthesis, x-ray diffraction characterization, and thermal properties

Double complex salts (DCSs) with [M(NH₃)₅Cl]²⁺ (M = Rh, Ir, Co, Cr, Ru) cations and [PtBr₄]^2? anions were prepared in high yields. The salts were two-phase mixtures of the anhydrous and monohydro DCSs. Anhydrous analogues containing [PdBr₄]^2? anions with M = Cr or Ru were synthesized. All the compounds were characterized using a set of physicochemical methods. The crystal structure of chloropentaamminechromium(III) tetrabromopalladate(II) was solved: space group Pnma, Z = 4, a = 17.068(2) Å, b = 8.315(12) Å, c = 9.653(14) Å. The [M(NH₃)₅Cl][M′X₄] (M = Rh, Ir, Co, Cr, Ru; M′ = Pd, Pt; X = Cl, Br) compounds were shown to be isostructural. The [M(NH₃)₅Cl][PtBr₄] · H₂O monohydrates are isostructural to the [M(NH₃)₅Cl][PdCl₄] · H₂O monohydrates (space group P2₁/c, z = 4). The properties of the compounds were comparatively analyzed. The tendencies of the thermal stability of the complexes were elucidated. The thermolysis products of the double complex salts obtained under a helium or hydrogen atmosphere were studied.     

Bimetallic palladium(II) and iron(III), titanium(IV), vanadium(V), cobalt(II), and copper(II) complexes with the [As2W19O67(H2O)]14− heteropolyanion

The formation of bimetallic Pd(II) and M = Fe(III), Ti(IV), V(V), Co(II), or Cu(II) complexes with the two-vacancy [As₂W₁₉O₆₇(H₂O)]^14? heteropolyanion (HPA) (below referred to as As₂W₁₉) has been studied by UV/Vis and IR spectroscopy and differential dissolution. In an aqueous solution at pH 6 and a Pd: M: As₂W₁₉ molar ratio of 1: 1: 1, heteropoly complexes (HPC) incorporating two different metals one being Pd(II) are formed. The resulting complexes were precipitated from solution as cesium salts. In the case of Pd(II) and M = Fe(III), Co(II), or Cu(II) ions, the precipitate contained bimetallic HPC [As₂W₁₉FePDO₆₇(H₂O)₂]^9? (65.9 wt %), [As₂W₁₉CoPdO₆₇(H₂O)₂]^10? (45.6 wt %), and [As₂W₁₉CuPdO₆₇(H₂O)₂]^10? (50.7 wt %) mixed with monometallic HPC [As₂W₁₉M₂O₆₇(H₂O)₂]^{(14 ? 2m)?} (As₂W₁₉M₂). In the case of Pd(II) and Ti(IV) or V(V), bimetallic HPC of a different composition were precipitated, namely, [As₂W₁₉Ti₂O₆₇(OH _x )₂ PdO]^{(10 ? 2x)?} (76.8 wt %) and [As₂W₁₉V₂O₆₇(OH _x )₂ PdO]^{(8 ? 2x)?} (15.0 wt %), where palladium ions are not incorporated in the HPC structure but are attached to the HPC surface, possibly, as hydroxide species. Using M = Pd(II), Ti(IV), V(V) ions and the HPA As₂W₁₉ ([M]: [As₂W₁₉] = 2 : 1, pH 6), new monometallic HPC, [As₂W₁₉Pd₂O₆₇(H₂O)₂]^10?, [As₂W₁₉Ti₂O₆₇(OH _x )₂]^{(10 ? 2x)?}, and [As₂W₁₉V₂O₆₇(OH _x )₂]^{(8 ? 2x)?} (x = 0, 1, or 2), were obtained.     

Preparation and properties of the formamidino complexes [M(π-C5H5){HC(NR)2}(CO)2] (M = molybdenum or tungsten; R = aryl or alkyl)

The preparation and properties of the complexes [M(π-C₅H₅){HC(NR)₂}CO)₂] (M = Mo, W; R = aryl or alkyl) are reported. The complex [Mo(π-C₅H₅){HC(N-p-tolyl)₂}(CO)₂] could be prepared by (a) reaction of MoCp(CO)₃Cl with M′{HC(N-p-tolyl)₂} (M′ = K, Ag or Cu); (b) irradiation of MoCp(CO)₃Cl with HC(HN-p-tolyl)N-p-tolyl); and (c) reaction of [MoCp(CO)₃]₂ with M′{HC(N-p-tolyl)₂} (M′ = Ag or Cu). The several routes to this complex give indications of the mechanisms of formation. The structure of these complexes and the bonding nature of the metal with the formamidino group is discussed on basis of the ¹H and ¹³C NMR and IR spectra.Reaction of N,N′-dimethyl formamidine with MCp(CO)₃Cl gave the complex [M(π-C₅H₅){HC(NMe)N(CO)Me}(CO)₂], containing a carbonyl inserted between the metal and the formamidino group. Irradiation of this carbamoyl complex caused decarbonylation, yielding the complex [M(π-C₅H₅){HC(NMe)₂}CO)₂].     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from bis[N-(2-hydroxynaphthalen-1-yl)methylene]oxaloyldihydrazide

The complex [Mn(L)(H₂O)₂] [H₄L = bis[N-(2-hydroxynaphthalen-1-yl)methylene]-oxaloyldihydrazide] reacts with activated ruthenium(III) chloride in methanol in 1:1.2 M ratio under reflux resulting in heterobimetallic complex of the composition [Mn(L)(H₂O)₄RuCl₂]Cl. The complexes of the composition [Mn(L)(A)₄RuCl₂]Cl were obtained when the above reaction was carried out in presence of heterocyclic nitrogen bases(A) such as pyridine(py), 3-picoline(3-pic) and 4-picoline(4-pic). The molar conductance values for these complexes in DMF(N,N-dimethyl formamide) solution indicate their 1:1 electrolytic nature. Magnetic moment values suggest that these heterobimetallic complexes contain Mn(IV) and Ru(III) in the same structural unit. Electronic spectral studies suggest six coordinated metal ions in these complexes. IR spectra reveal that the H₄L ligand coordinates in its keto-form to Mn(IV) and Ru(III).