Russian Chemical Bulletin, International Edition, Vol. 56, No. 10, pp. 1956—1959, October, 2007 1956 Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1890—1893, October, 2007. 1066-5285/07/5610-1956 © 2007 Springer Science+Business Media, Inc. Chemiluminescence in the reaction of LnI 2 (Ln = Dy, Nd) with water R. G. Bulgakov, a S. P. Kuleshov, a Z. S. Kinzyabaeva, a A. A. Fagin, b I. R. Masalimov, a and M. N. Bochkarev b a Institute of Petroleum Chemistry and Catalysis, Russian Academy of Sciences, 141 prosp. Oktyabrya, 450075 Ufa, Russian Federation. Fax: +7 (347 2) 31 2750. E-mail: ink@anrb.ru b G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 ul. Tropinina, 603950 Nizhnii Novgorod, Russian Federation. Fax: +7 (831 2) 62 7497. E-mail: mboch@iomc.ras.ru Сhemiluminescence (CL) upon the reaction of crystalline LnI 2 (Ln = Dy, Nd) with water was found. The CL emitters are the Ln 3+ * electron-excited ions (Dy 3+ *, λ max = 470, 570 nm; Nd 3+ *, λ = 700—1200 nm) generated by the electron transfer from the Ln II ions to the H 2 O molecules. The identified reaction products are H 2 , dissolved LnI 3 , and insoluble LnI(OH) 2 (49—51% and 48—50% yield for DyI 2 and NdI 2 , respectively). The treatment of NdI 2 with an H 2 O solution in THF gives the NdI 2 OH(thf) 2 •3H 2 O complex and hydrogen. Key words: dysprosium, neodymium, diiodides, chemiluminescence, hydrolysis, photolu- minescence. Chemiluminescence (CL) involving Ln II compounds, unlike Ln III compounds, was studied to less extent. The CL is known for the EuCl 2 complexes with organic ligands 1—3 and Cp 2 Yb, 4 Cp 2 Sm, and Cp 2 Eu lanthanido- cenes (see Refs 5 and 6) upon oxidation with hydrogen peroxide and molecular oxygen. In all cases, the CL emit- ters are the excited Ln 3+ * ions: Eu 3+ *, Yb 3+ *, and Sm 3+ *. The Eu II , Yb II , and Sm II compounds are rather stable, (E°(Ln 3+ /Ln 2+ ) = –(0.34—1.50 V) 7,8 ), whereas the compounds of other Ln II (Ln = Nd, Dy, and Tm) with very low oxidation potentials (E°(Ln 3+ /Ln 2+ ) = –(2.22—2.62 V) 7,8 ) are extremely unstable; they have been synthesized rather recently. 9—11 The properties of these compounds were studied to less extent, and their CL has not recently been examined. Therefore, investigation of the physicochemical properties of the labile Nd II and Dy II compounds is urgent. In this work, we studied for the first time the ability of DyI 2 (1) and NdI 2 (2) to enter chemical reactions and generate radiative excited states Ln 3+ *. The interaction of compounds 1 and 2 with water was chosen as this reac- tion. The reaction has not been studied earlier: CL was not detected and no stable products were identified. Experimental Crystalline samples 1 and 2 (content of the main substance 95 and 93%, respectively) were synthesized according to earlier described procedures. 9,10 Bidistilled water was used; THF was purified by reflux over NaOH and metallic sodium and prior to use it was kept for 15 min over compound 1 or 2 for the addi- tional purification from water traces. For recording IR spectra, the samples were prepared as a suspension in Nujol and placed between NaCl plates. Photolu- minescence (PL) spectra were recorded on a home-made spectrofluorimeter designed on the basis of an MDR-23 double monochromator. Absorption spectra were measured on Specord M-40 (UV-visible region) and Specord M-40 (IR region) spec- trophotometers. Chemiluminescence measurements. To measure the CL ki- netics, a powder of compound 1 (18.20 mg, 0.04 mmol) or 2 (15.92 mg, 0.04 mmol) was placed under argon on the bottom of a glass cell mounted in a light-tight chamber of the chemilumi- nescence setup. 12 Water (2 mL) was added for 3 s from a doser to the cell, and CL was detected. The spectra of CL arisen upon the hydrolysis of compounds 1 (91.40 mg, 0.22 mmol) and 2 (87.60 mg, 0.22 mmol) were measured using a set of cut-off color filters according to a known procedure 13 with FEU-39 (for 1) and FEU-83 (for 2) photomultipliers cooled with liquid nitrogen as light receivers. When measuring the CL spectra, an aliquot of water (2 mL) was added to compound 1 (or 2) or argon containing water vapor, which was obtained by purging argon through a bottle filled with water, was supplied. Reactions of compounds 1 and 2 with liquid water. The reac- tions were carried out in an ampule filled with argon and con- nected to a gas burette. Water (5 mL) was added dropwise at 0 °С to compound 1 (1.39 g, 3.34 mmol). After gas evolution ceased completely, more water (15 mL) was added to the reac- tion mixture, the mixture was centrifuged, and a light blue solu- tion was separated from the precipitate by decantation. The precipitate was washed with MeOH (10 mL) and dried in vacuo. The yield of DyI(OH) 2 •H 2 O was 0.494 g (82.4%). Found (%): Dy, 47.03; I, 38.26. H 4 IDyO 3 . Calculated (%): Dy, 47.59; I, 37.17. The reaction of compound 2 with water was carried out similarly. Diiodide 2 (1.28 g, 3.22 mmol) gave NdI(OH) 2 •H 2 O (0.425 g, 74%). Found (%): I, 38.26; Nd, 45.74. H 4 INdO 3 .