Transition Met. Chem., 15, 273-277 (1990) Dinitrosoresorcinol Fe, Co and Ni complexes Synthesis and characterisation of complexes of iron(II, III), cobalt(II, III) and nickel(II) with dinitrosoresorcinol Ramadan M. Awadallah*, Adila E. Mohamed, Mohamed A. El Maghraby and Abd El Mottaleb M. Ramadan Depa~tment of Chemistry, Faculty of Science, Aswan, A.R. Egypt 273 Summary Complexes of Fe l~, Fe m, Co u, Co m and Ni n with dinitroso resorcinol (DNR) have been isolated and characterised. [.r. studies showed that the metals are coordinated to the oxygens of one hydroxyl and one nitroso group, the second hydroxyl and nitroso groups remaining uncoordinated. The magnetic moments of the Fe" and Ni n complexes are commensurate with tetrahedral (or distorted octahedral) structures, while the others are octahedral; however, the electronic spectra suggest octahedral stereochemistries for all the complexes. Introduction In continuation of our earlier studies ~-3) on complexes of iron, cobalt and nickel with dibenzoylmethane, murexide, eriochrome black T, thenoyltrifluoroacetone, violuric acid and 2, 2-dipyridyl as N, S or O donors, we here report the results of the reactions of iron(II, II1), cobalt(II, III) and nickel(II) with dinitrosoresorcinol (DNR). Experimental All chemicals used were from Riedel de Hfien, BDH or E. Merck and of AnalaR quality. Preparation of complexes The complexes were prepared by boiling aqueous solutions (1 mmol in t 0 ml) of (NHr 4. FeSO,' 6Hz O, FeC13"6HzO, COC12"6H20, Na[Co(NO2)6] or (NH4)zSO,'NiSO4"6HzO with EtOH solutions in appropriate metal:DNR molar ratios (1:1, 1:2 for Fe n, Co", Nin; 1:t, 1:2 and 1:3 for Fe nl, Co hI) under reflux for ca. 2h, then cooling. The solid complexes of Fem-DNR separated on addition of Et20, while those of Co m were separated by addition o1' acetone and the Ni"-DNR complexes separated by cooling alone. The solutions of Con-DNR were reduced by evaporation to a small vol on a water bath. A small vol of EtOH was added to dissolve any unreacted ligand or metal chloride and this treatment was repeated, whereby the solid complexes precipitated. The reaction mixtures of FeU-DNR were evaporated to a small vol then an M%Co C6H 6 (1: I) mixture (20cm 3) was added and the solid complexes were separated. The complexes were filtered off, washed 7-10 times using the precipitants (3cm 3 portions) and then dried in a desiccator over P,O~o. Analyses of Fe, Co and Ni contents were carried out by atomic absorption spectrophotometry (Pye Unicam 1900 Atomic Absorption Spectrophotometer), after destruction of the complexes with HNO 3. Chloride was determined titrimetrically by the mercuric nitrate * Author to whom all-correspondenceshould be directed. method ~4) at Aswan, Faculty of Science. C, H, N, S were determined microanalytically at the Microanalytical Centre of Cairo University. Physical measurements Magnetic measurements of the solid complexes were made at room temperature (27 ~C) by the Gouy method at the Faculty of Science, Alexandria. Conductometric titrations were carried out by titrating specific volumes (Vt) of 1 x 10 -3 M aqueous solutions of metal ions with aliquots (0.5 ml) of 1 x 10 -2 M DNR and measuring the conductances after stirring the solutions magnetically for 3 rain at 30 ~C. The specific conductances were corrected for dilution [2(V 1 + Vz)/V1]. Conductometric measure- ments were made using a constant concentration of DNR, keeping the total vol constant (10 cm 3 volumetric fask), and thermostatting the solutions at 35~ for 2 h. Molar conductivities of the solutions (1 x 10- 2 M in DMF) were measured using a WPA CM 25 conductivity meter, Saffron Walden, at Aswan, Faculty of Science. Thermal (d.t.a. and t.g.a.) analyses of the powdered ( - 200 mesh) complexes (ca. 18 rag) were recorded using a Shimadzu DT-30 Apparatus at the Research Centre, E1 Mansoura University. I.r. spectra of the ligand and the solid complexes as KBr discs were recorded on a Perkin-Elmer 183 Recording Spectrophotometer in the range 4000-200cm-1 at Assiut, Faculty of Science. Electronic spectra were obtained as nujol mulls on Whatman no. 1 filter paper. A reference window-free-material was used to compensate light scattering and the mulls, as well as DMF solutions, were scanned in the 300-700rim range using a Shimadzu Recording Spectrophotometer model UV-240. Melting points were measured using a hot plate melting point apparatus reading up to 500~ The specific gravities of the air-free powdered complexes were measured with a pyknometer using bromobenzene as displacement liquid. Results and discussion The data obtained are recorded in Table 1. The overall stepwise reaction between metal ions and ligand leads to the formation of [M(DNR)], [M(DNR)2] and [-M(DNR)3q complexes. The complexes are fairly soluble in water, ethanol and DMF and have high melting points. The melting points and specific gravities of complexes decrease slightly in the order: MX(DNR) > M(DNR)2 > M(DNR)3. The conductance values of the complexes as 1 x 10 3M solutions in DMF (MX.DNR + DMF~M-DNR.DMF + H + + X-, M(DNR)2 +2DMF~---M(DMF)2 + 2H + +2DNR-, M(DNR)3 + 3DMF.~---M(DMF)3 + 3H + + 3DNR-) are in excellent agreement with the reference values (5). Thermogravimetric and differential thermal analyses The thermogravimetric measurements of the complexes 0340-4285/90 $03.00+ .12 9 1990Chapman and Hall Ltd