Kinetics of thermal dehydration of some bis-(4-aminosalicylato)-diaquo complexes of transition metal ions

The kinetics of thermal dehydration of bis-(4-aminosalicylato)-diaquo complexes of VO(II), Cu(II), Ni(II), Co(II), Fe(II) and Mn(II), were studied. The activation energies and other kinetic parameters have been evaluated. The observed kinetic parameters indicate a first-order reaction. The activation energy of the thermal dehydration decreases in the order: VO(II) > Cu(II) > Co(II) > Ni(II) > Fe(II) > Mn(II), which is also the order for the covalency in the MO bonds.     

Oxythallation of norbornene derivatives with thallium(III) acetate in methanol

Treatment of norbornene, norbornadiene, benzonorbornadiene, and chloro- and methoxy-benzonorbornadiene with thallium(III) acetate in methanol affords only the corresponding cis-exo-acetoxythallation adducts in a sharp contrast to oxymercuration of such strained olefins where methoxymercuration prevails. In the cases of substituted benzonorbornadienes the products are obtained as the regioisomeric mixtures, the isomer ratio being determined by ¹³C NMR. In the cases of 5-norbornene-2,3-dicarboxylic anhydride, 5-norbornene-2-methyl-2,3-dicarboxylic anhydride, and 5-norbornen-2-endo-carboxylic acid, lactonization occurs to give a trans-oxythallation adduct having a lactone ring, no introduction of either methoxy or acetoxy groups being observed. ¹H and/or ¹³C NMR data for several new oxythallation adducts are provided. The alkaline sodium borohydride reduction of adducts in methanol affords mainly the parent olefin together with 10–16% yields of the corresponding exo-alcohol.     

Synthesis and characterisation of a new mixed [Si(IV), Al(III)] μ-oxo-isopropoxide and its acid complexes

Reaction of dimethyldiacetoxysilane with aluminium isopropoxide was carried out in 1 : 2 molar ratio in refluxing cyclohexane and a mixed [Si(IV), Al(III)] μ-oxo-isopropoxide of the composition Me₂SiO₂Al₂(OPrⁱ)₄ was isolated. This compound was characterised by elemental analysis and IR and NMR spectral studies. The tertiary butanol derivative, Me₂SiO₂Al₂(OBu^t)₄, was prepared by alcoholysis. Reactions of this mixed [Si(IV), Al(III)] μ-oxo-isopropoxide with monobasic bidentate carboxylic acids, such as trans-cinnamic acid (HCA) and dihydrocinnamic acid (HDCA) and with dibasic tridentate carboxylic acids such as salicylic acid (H₂SA) and benzilic acid (H₂BA) were also studied. Products of the type Me₂SiO₂Al₂(OPrⁱ)_4-n(L)_n [where HL = trans-cinnamic acid (HCA), dihydrocinnamic acid (HDCA) and n = 1,2,3 or 4] and Me₂SiO₂Al₂(OPrⁱ)_4-2n(L)_n [where H₂L = salicylic acid (H₂SA), benzilic acid (H₂BA) and n = 1 or 2] were isolated and characterised by elemental and spectral studies.     

Studies on the structure and thermal behaviour of the Mn—urea complex

The urea complex of manganese was synthesized and its structure established to be [Mn(Urea)(H₂O)₃Cl₂] from elemental analyses, IR and UV and visible spectroscopy and magnetic susceptibility measurements. The thermal behaviour has been studied by thermogravimetry (TG) in nitrogen and air atmospheres and differential thermal analysis (DTA) in air. TG analysis shows three main steps of decomposition leading to oxide formation in the final stage when the complex is heated in air, and MnCl₂ formation when it is heated in nitrogen. The kinetics of decomposition of the complex have been studied. Plots of the Coats—Redfern equation show two breaks from which three values of the activation energy are reported. From the results, it is concluded that decomposition of the complex is a heterogeneous process.     

Bis- and tris-(trimethylsilyl)methyl derivatives of antimony

Reaction of RMgCl [R = (Me₃Si)₂CH) with SbCl₃ affords RSbCl₂. Also R₂SbCl reacts with RLi to yield R₃Sb, while R′SbCl₂ [R′ = (Me₃Si)₃C] is synthesized from R′Li and SbCl₃. Mass spectra of RSbCl₂ and R′SbCl₂ show that fragmentations proceed with elimination of Me₃SiCl. The chlorides RSbCl₂, R₂SbCl and R′SbCl₂ are thermally very stable.     

Alkali-metal trifluoromonosulphatomanganates (III) A2[MnF3(SO4)] (A = NH4, Li,Na or K)

Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A₂[MnF₃(SO₄)] (A = NH₄, Li, Na or K), have been synthesised in high yields by reacting KMnO₄ or MnO(OH) with 40% HF and A₂SO₄ or by the reaction of MnO(OH) with 40% HF and A₂S₂O₈ (A = NH₄ or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH₄)₂[MnF₃(SO₄)] on being pyrolysed at 340°C yields MnSO₄.     

Studies on iron(III) complex with 5,6-diamino-1,3-dimethyluracil

Reaction of 5,6-diamino-1,3-dimethyluracil (DDU) with iron(III) ion gave a fine blue colouration due to the formation of Fe[(DDU—H)₃]·2HClO₄. An oxidation product (7), C₁₂H₁₂N₆O₄, was also isolated from the reaction mixture.     

Some trimethylphosphineoxide complexes of lanthanide and indium tris-(bis-trimethylsilylamides)

The reactions of the 3-coordinated metal tris-(bis-trimethylsilylamides) M[N(SiMe₃)₂]₃ (ML₃; where M = La, Pr, Eu, Gd and In) with trimethylphosphineoxide Me₃PO(L′) have been studied. All of these metals gave 1:1 complexes ML₃(L′) which dissociated on heating in vacuo. The Pr and Eu complexes gave interesting pseudo-contact shifted ¹H NMR spectra which are qualitatively in accord with the expected molecular structure. Variable temperature NMR measurements proved the restricted rotation of the silylamide (L) ligands occurs around the M–N axes. Evidence is also presented for unstable 5-coordinated complexes ML₃(L′)₂. The gadolinium 1:1 complex gave a very broad NMR spectrum and its ESR spectrum is being investigated.     

Photochemistry of planar four-co-ordinate palladium(II) complexes—III. Photosynthesis and crystal structure of [Pd2(PPr3n2(NCS)(SCN)2(μ-CN)]

U.V. irradiation of MeOH and CH₃CN solutions of trans-[Pd(PPr₃ⁿ)₂(NCS)₂] causes a stepwise photochemical reaction. When the solvent is CH₃CN the photoproduct can be conveniently isolated in a crystalline form. This compound has been shown, by X-ray analysis, to be a cyano bridged palladium(II) complex.     

The ferric chloride α-DI-imine systemVI: Electronic structure of the dimethyl formamide addcut of mono-1,10-phenanthroline ferric chloride and the by-product,tris-1,10-phenanthroline ferrous μ-oxo-bis[trichloro ferrate(III)]; field induced slow paramagnetic relaxation in monomeric ferric complexes

Magnetic susceptibility (1.45–300 K), zero and high field Mössbauer spectroscopy, IR and solution conductivity measurements were used to characterize the title DMR adduct, Fe(phen)Cl₃·DMF. The absence of magnetic hyperfine splitting in zero external field is correlated with D positive corresponding to an isolated, rapidly relaxing ground (M_s = ± $\text{1}\text{2}$ Kramers doublet. X-ray data show that the ferric ion centres are apparently sufficiently close (～ 7 Å) to allow for rapid spin-spin relaxation via dipolar interactions. The application of longitudinal magnetic fields (0–5 Tesla for 1.7–4.2 K) slows relaxation and results in fully resolved Zeeman split Mössbauer spectra for which the effective internal field, H_n = 354 kG at 1.7 K for H₀ = 5T. The complex [Fe(phen)₃] [O(FeCl₃)₂] contains an unusual binuclear anion based on tetrahedral FeOCl₃ units as recently found in [pyridinium]₂[O(FeCl₃)₂] and is obtained as a trace by-product in our preparation of Fe(phen)Cl₃·DMF. Further magnetic characterization of the latter pyridinium compound is presented.     

Magnetic susceptibility and ESR studies of three complexes of chromium(III) and L-histidine. Ferromagnetic interactions in the dimeric complex [Cr(L-histidine)2(OH)]2

Three complexes of chromium(III) and histidine were investigated by variable temperature magnetic susceptibility and ESR. Two monomeric stereosoimers of Cr(L-histidine)₂(NO₃) were studied; the trans(imidazole) and trans(carboxylate)isomers exhibited Curie-Weiss behaviour in the 6–300 K temperature region. The magnetic susceptibility of the related binuclear complex, [Cr(L-histidine)₂(OH)]₂, showed ferromagnetic behaviour at low temperature (J/k = +0.15 K) lending strong support to the proposed hydroxo-bridged structure.     

Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Alkylenedithiophosphate derivatives of arsenic(III), antimony(III) and bismuth(III)

Tris(alkylenedithiophosphates) of arsenic(III), antimony(III) and bismuth(III),

have been synthesized by the reactions of alkylenedithiophosphoric acids with metal oxides and chlorides and of their ammonium salts with metal chlorides in suitable solvents. Mixed chloride alkylenedithiophosphates of arsenic(III) and antimony(III),

have been obtained by the reactions of metal chlorides with ammonium alkylenedithiophosphates at 1 : 1 and 1 : 2 molar ratios or alternatively by the co-disproportionations reactions of metal chlorides with metal tris(alkylenedithiophosphates) at different (2 : 1 and 1 : 2) molar ratios. These new compounds have been characterized by elemental analyses, molecular weight measurements and spectroscopic (IR, and ¹H and ³¹P NMR) data. Chelated structures with bidentate alkylenedithiophosphate groups have been proposed for all these derivatives.     

Kinetics of the thermal dehydration of trans-fluoroaquobis(ethylenediamine)chromium(III) tetracyanometallate(II) [metal(II) = Ni(II), Pd(II) and Pt(II)]

The solid phase thermal deaquation—anation of trans-[CrF(H₂O)(en)₂][M(CN)₄] (M = Ni, Pd, Pt; en = ethylenediamine) has been investigated by means of non-isothermal DSC and isothermal and non-isothermal TG measurements. The physical model for these reactions (nucleation, growth, diffusion or intermediates) has been found by comparison of the isothermal and non-isothermal TG data for all the principal g(α) expressions (0.2?α?0.8) and by the shape of the isothermal curves. The values found for activation energy are low (～ 130 kJ mol^?1 for the Ni compound, ～ 140 kJ mol^?1 for the Pd compound, and ～ 100 kJ mol^?1 for the Pt compound). These data permit the assignment of the deaquation—anation mechanism of the S_N1 type involving a square-base pyramid activated complex and elimination of water as Frenkel defects.     

Ln(GaM2+)O4 and Ln(AlMn2+)O4 compounds having a layer structure [Ln = Lu,Yb, Tm,Er, Ho,and Y,and M = Mg,Mn, Co,Cu, and Zn]

A series of new compounds Ln(GaM²⁺)O₄ and Ln(AlMn²⁺)O₄ having a layer structure were successfully prepared [Ln = Lu, Yb, Tm, Er, Ho, and Y, and M = Mg, Mn, Co, Cu, and Zn]. The synthesis conditions and the unit cell parameters for 23 compounds have been determined. These compounds are isostructural with YbFe₂O₄ (space group $\text{R}\text{3}\text{m, a = 3.455(1)}$ Å, and c = 25.109(2) Å).     

Improved syntheses of chlorodicyclopentadienyl derivatives of scandium(III), titanium(III) and vanadium(III)

An improved synthesis of chlorodicyclopentadienyl derivatives of scandium(III), titanium(III) and vanadium(III) has been developed by the reaction of thallium cyclopentadienide with the appropriate anhydrous metal trihalides.     

Synthesis and crystal structure of [N,N′-bis(2,3,5,6-tetrafluorophenyl)-ethane-1,2-diaminato(2-)]dipyridineplatinum(II)

The reaction of PtCl₂en (en = ethane-1,2-diamine) with TlO₂CC₆F₅ in boiling pyridine unexpectedly yielded a polyfluorophenyl-stabilized ethane-1,2-diaminatoplatinum(II) complex, Pt[N(p-HC₆F₄)CH₂]₂(py)₂, 1a, the structure of which has been established by X-ray crystallography.     

Equilibrium study of the systems of aluminium(III), gallium(III) and indium(III) with mercaptoacetate, 3-mercaptopropionate and 2-mercaptobenzoate

Equilibrium studies were carried out by pH-potentiometry on the systems of aluminium(III), gallium(III) and indium(III) with mercaptoacetate (MerAc^2?), 3-mercaptopropionate (MerPr^2?) and 2-mercaptobenzoate (MerBe^2?). It was found that the complex-forming properties of the Al³⁺ ion towards these mercaptocarboxylic acid ligands differ from those of Ga³⁺ and Al³⁺. Under the conditions of the study, Al³⁺ forms only hydroxo complexes, while Ga³⁺ and In³⁺ form relatively stable complexes involving the simultaneous coordination of the carboxylate and the deprotonated mercapto group. In all cases the equilibrium systems can be described without the assumption of polynuclear complexes. The complexes Ga(MerAc)₂ and Ga(MerBe)₂ show marked stability; this was interpreted in terms of back-coordination and of interaction between the d¹⁰ electrons of the Ga³⁺ ion and the empty d orbitals of the S donor atom. Complexes of composition ML_i are not formed in the Ga³⁺-MerPr^2? system; this points to the importan roles of the number of atoms in the chelate ring and the higher stability of the Ga(III)-hydroxo complexes.     

Metal complexes of mercaptoamines—III. Different behaviour of β- and γ-(N,N-dimethyl)-mercaptoamines

The complexes Ni₆(MPDMA)₁₂, [Ni₆(MPDMAH)₁₂]X₁₂ X = (I, ClO₄) and Pd₂(MPDMA)₂Cl₂ (MPDMA = ^t-S(CH₂)₃N(CH₃)₂) have been prepared and characterized. An X-ray diffraction study shows that the structure of [Ni₆(MPDMAH)₁₂] (ClO₄)₁₂ consists of a cyclic hexanuclear array of nickel atoms linked by sulphur bridging ligands. Infrared and electronic spectra show that there is no chelation in any of the nickel complexes. However, coordination through the nitrogen atoms occurs in the palladium complex. This behaviour differs from that of the homologous β-mercaptoamine, which forms monomeric chelate complexes with both nickel and palladium.     

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.