Thermal decomposition kinetics of thiophene-2-carboxaldehyde thiosemicarbazone complexes of nickel(II) and palladium(II)

The thermal analysis of Ni(II) and Pd(II) complexes with thiophene-2-carboxaldehyde thiosemicarbazone have been studied using TG technique. Their decompositions are subjected to critical evaluation using the equations of Coats-Redfern, Horowitz-Metzger and modified Horowitz-Metzger and the kinetic parameters (non-isothermal method) have been evaluated for each step of decomposition by the method of weighted least-squares.     

Complexes of platinum,rhodium, iridium and ruthenium with a thiosemicarbazone derived from thiophene-2-carboxaldehyde

Summary Complexes of thiophene-2-carboxaldehyde thiosemicarbazone with Ru^III, Rh^III, Ir^III and Pt^IV have been prepared and characterized by elemental analyses, molar conductance, room temperature, magnetic moments, infrared and electronic spectral studies. Probable structures for the complexes are suggested. All are diamagnetic except the Ru^III complexes and possess octahedral structures. The crystal field parameters of the complexes have also been calculated.     

Pyridine-2-carboxaldehyde as ligand: synthesis and derivatization of carbonyl complexes

Thermally induced carbonyl substitutions on [M(CO)5X] (M=Mn, X=Cl, Br; M=Re, X=Br) or room temperature displacement of acetonitrile from [Mo(eta3-methallyl)Cl(CO)2(NCMe)2] produce stable crystalline complexes containing pyridine-2-carboxaldehyde (pyca) as chelate kappa2(N,O) ligands (). These react with ethylglycine to afford iminopyridine complexes containing an amino ester pendant arm in high-yield. Treatment with silver salts produce halide abstraction affording neutral complexes containing coordinated perchlorate or triflate which can be replaced by triphenyl phosphine to give cationic complexes . As confirmed by spectroscopy and X-ray crystallography the pyca ligand remains bonded as chelate kappa2(N,O) throughout these processes.     

Phthalazine iron carbonyl complexes

Reaction of phthalazine with diiron enneacarbonyl in benzene at room temperature and with triiron dodecacarbonyl in hot benzene gives mono- and binuclear complexes where the nitrogen atoms behave as two- or three-electron donor ligands. 1,2-Dihydrophthalazine and a binuclear iron carbonyl derivative are formed when the triiron dodecacarbonyl reaction is effected in methanolic benzene.     

Synthesis and characterization of new metal complexes of thiosemicarbazone derived from 4-phenyl-3-thiosemicarbazide and chromone-3-carboxaldehyde

Summary The reaction between chromone-3-carboxaldehyde-4-phenylthiosemicarbazone (HCPT) and some hydrated metal salts of Co^II, Ni^II and Cu^II give complexes of the type [Cu(HCPT)Cl₂],[Cu(CPT)BrH₂O],[Cu(CPT)₂]·2H₂O, [Ni(CPT)₂(H₂O)₂]·2H₂O, [Co(CPT)₂(OAc)] and [Co(CPT)₂(H₂O)₂]X·2H₂O (where X=Cl or Br). The metal complexes were characterized by elemental analyses, molar conductivities, and spectal (i.r. and visible) and magnetic studies. I.r. spectra show that the HCPT coordinates in the thione or thiol form and behaves in a bidentate manner. Also, HCPT behaves as an oxidizing agent towards Co^II forming diamagnetic Co^III complexes. An octahedral structure is proposed for both Co^III and Ni^II complexes, while a square-planar structure is proposed for Cu^II complexes on the basis of magnetic and spectral measurements.     

Reactions of iron carbonyl complexes with dimethylthiocarbamoyl chloride

The reactions of dimethylthiocarbamoyl chloride with a number of neutral and ionic iron carbonyl complexes in tetrahydrofuran are described. A variety of unusual products were obtained, viz. Fe(CO)₂(S₂CNMe₂)₂ from Fe(CO)₅; Fe(CO)₂(S₂CNMe₂)(CSNMe₂) from Fe₂)CO)₉, Fe₃(CO)₁₂, and Fe(CO)₄^2?; [Fe-(CO)₂(S₂CNMe₂)(CNMe₂)(CNMe₂)₂S]⁺ from Fe(CO)₄^2?, and Fe₄(CO)₁₂S(CSNMe₂)-(CNMe₂) from Fe₂(CO)₈^2?, as well as Fe₂(CO)₆(CSSEt)₂ from Fe₂(CO)₉ and ClCSSEt. The structures and behavior and some reactions of these complexes are described.     

The first carbonyl iron complexes with dihydroacepentalene ligands

1,4-Dibromo- (8) as well as 1,4,7-trichloro- (11a) and 1,4,7-tribromotriquinacene (11b) react with Fe₂(CO)₉ in THF to yield (dihydroacepentalene)hexacarbonyldiiron complexes 9 and 10, the first representatives with a 7,10-dihydroacepentalene ligand. By reaction with Fe₂(CO)₉, the readily accessible 4,7-bis (dialkylamino)tricyclo[5.2.1.0^4.10]deca-1(10),2,5,8-tetraenes 14, derivatives of the unknown 4,7-dihydroacepentalene, were transfomed into their tricarbonyliron complexes 15. Upon reduction with sodium in THF, the η⁴-(diene)tricarbonyliron 15 selectively gave the novel 1,10η²-(olefin)tricarbonylferrates(-2)17 as a result of a twofold electron transfer. The intermediate green radical anion 16, which is persistent in the absence of excess sodium, was characterized by its ESR signal. Complexes 17 are the first of their class with complete structural characterization by ¹H- and ¹³C-NMR spectroscopy.     

Thermal decomposition kinetics of bis(thiophene-2-carboxaldehyde thiosemicarbazonato) cobalt(II)

The thermal decomposition kinetics of thiophene-2-carboxaldehyde thiosemicarbazone complex of cobalt(II) has been studied using TG, DTG and DTA techniques. Its decomposition was subjected to critical evaluation using the equations of Freeman-Carroll, Horowitz-Metzger and Coats-Redfern and the kinetic parameters have been evaluated for each step of decomposition by the method of weighted least squares.

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Co(II) -2- , . -, - -. .

     

Dinuclear iron carbonyl complexes of 3H-1,2-diazepines

3H-1,2-Diazepines ($\text{1}\text{2}$) give dinuclear complexes ($\text{3}\text{4}$) on reaction with diiron nonacarbonyl. Complexation much reduces the rate of the [1,5] sigmatropic hydrogen shift across the diazepine ring and also reduces the activation energy for ring inversion.     

Transfer processes of alkoxyl groups in iron carbonyl complexes

The mass spectra of Fe₂(CO)₆C₄(COOCH₃)₄ and Fe₂(CO)₆C₄(COOC₂H₅)₄ are reported. Transfer processes of alkoxyl groups and hydrogen rearrangements are observed, and confirmed by deuterium labelling and the observation of metastable transitions. Fe₃(CO)₈C₄(COOCH₃)₄ and Fe₃(CO)₈C₄(COOC₂H₅)₄ give similar breakdown patterns. Likely fragmentation schemes are suggested.     

Nickel(II) complexes of a thiosemicarbazone prepared from 2-Acetylpyridine

Summary The ligand 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(2-pyridinyl)ethylidene]hydrazide (HL), which is observed in an unusual tautomeric form in the solid state, and its selenium analogue (HLSe) have been used to prepare a series of nickel(II) complexes. Compounds of the general formula [NiLX] (X=Cl, Br, NCS, N₃, NO₂ or NCSe) as well as [Ni(LSe)Cl] have been found to be diamagnetic, planar complexes. A single crystal study of [NiL(NCS)] shows the deprotonated ligand bound in a tridentate mannervia its pyridyl nitrogen, imine nitrogen and the thione sulphur atom with the nitrogen atom of the thiocyanato-ligand occupying the fourth coordination position. The solids prepared from the nickel(II) salts having tetrafluoroborate, nitrate and iodide ions approximate to octahedral symmetry and have neutral HL ligands coordinated in a bidentate fashionvia the pyridine and imine nitrogens with the remaining coordination sites being occupied by the anions or water molecules. The [NiL₂] solid is also octahedral with the two deprotonated ligands bonding as tridentate groupsvia the same atoms as in the [NiLX] complexes.     

Synthesis,spectroscopy and structures of halogen and sulfur-bridged dinuclear silver(I) complexes with N1-substituted thiophene-2-carbaldehyde thiosemicarbazone

The reactions of silver(I) halides (Cl or Br) with thiophene-2-carbaldehyde N¹-methyl thiosemicarbazone (HttscMe) in the presence of Ph₃P (1:1:1 molar ratio) yield halogen-bridged dimers, [Ag₂(μ-X)₂(η¹-S-HttsMe)₂(PPh₃)₂] (X = Cl, 1; Br, 2). The use of 2,2′-bipyridine in lieu of Ph₃P in the reaction of silver(I) chloride with HttscMe yields the sulfur-bridged dimer, [Ag₂(μ-S-HttscMe)₂(η¹-HttsMe)₂] · 2CHCl₃ 3. The substituents have altered the nature of bridge between the two silver atoms. The Ag···Ag separation (3.4867(5) Å) in complex 3 is less than that in the halogen-bridged dimers (3.734(4) Å 1; 3.746(5) Å 2). Unlike PPh₃ the co-ligand 2,2′-bipyridine did not coordinate to the silver center, but was necessary for crystallization in the reaction with the thio-ligand. NMR spectroscopy revealed that the complexes remained unchanged in the solution state (CDCl₃).     

Oxygen-17 and carbon-13 nuclear magnetic resonance spectra of thiophene- and pyrrole-2-carboxaldehyde condensation products prepared from ephedrine derivatives

Natural abundance ¹⁷O nmr (acquired in acetonitrile at 70°) and ¹³C nmr (acquired in deuteriochloroform at 37°) spectroscopic data for four oxazolidines and related imino alcohols are reported: relationships of chemical shifts and ¹⁷O line widths at half-heights to structures are discussed.     

Transition metal ion complexes of a thiosemicarbazone derived from 6-methyl-2-acetylpyridine

Summary A series of metal ion complexes of the thiosemicarbazone, 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(6-methyl-2-pyridinyl)ethylidene]hydrazide (6 MLH) have been prepared and spectrally characterized. The ligand undergoes deprotonation to coordinatevia the thione sulphur, the imine nitrogen and the pyridyl nitrogen. A single anionic ligand such as Cl^–, Br^– and NO₃ ^– completes the bonding to the Cu^II and Ni^II centre. The compound derived from CoCl₂ contains two 6 MLH ligands bound to a Co^II centre and a CoCl ₄ ^2– counter ion. Complexes derived from perchlorate salts may feature 6 MLH, 6 ML, or both with the Co^II being oxidized to Co^III. The solids were characterized by i.r., electronic and e.s.r. spectroscopy. In addition, electronic and e.s.r. spectra of their chloroform solutions were recorded.NATO Fellow, on leave from Istanbul Medical Faculty, Istanbul University.     

Intermediate spin iron(III) complexes of N4,N4-disubtituted 2-acetylpyridine thiosemicarbazone

Summary Magnetic susceptibility and Mössbauer spectroscopy measurements have been carried out on [Fe^III(SAm)Cl₂], and indicate an intermediate spin state for the ferric ion. The temperature-independent magnetic moment of (4.17±0.05) _B, the quadrupole splitting=4.09 mm s^–1 and isomer shift=0.133 mm s^–1 are in agreement with such formulation. These studies, together with infrared data, are used to suggest a possible structure of the complex.     

Synthesis and molecular structure of iron carbonyl complexes of germanium

Conclusions The authors have synthesized new iron carbonyl complexes of Ge with carbofunctional substituents at the germanium atom and investigated them by the x-ray structural method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 490–495, March, 1981.