I. INTRODUCTION
Oxygen atom transfer to or from a substrate, is a very delicate operation that is performed in nature by enzymes such as oxotransferasas or hidrosilasas, which mostly have molybdenum-oxygen entity (Mo = O) as the active site (Enemark et al., Reference Enemark, Cooney, Wang and Holm2004; Holm et al., Reference Holm, Solomon, Majumdar and Tenderholf2011). Numerous bio-inspired dioxo-Mo complexes have been synthesized and it has been observed that the transfer of oxygen and the stability of these complexes is directly related to the chemical environment (metal-ligand interaction) surrounding its active site (Arzoumanian, Reference Arzoumanian1998; Amini et al., Reference Amini, Haghdoost and Bagherzadeh2013). Among the innumerable bidentate chelating ligands used to obtain complexes with transitions metals, the 2,2′-bipyridine is certainly one of the most widely used because of its ability of introducing different substituents and modify its physical and chemical properties (Constable and Steel, Reference Constable and Steel1989; Ittel et al., Reference Ittel, Johnson and Brookhart2000). This property has allowed us to study the coordination sphere effect in the reactivity of the Mo = O entity (Kühn et al., Reference Kühn, Lopes, Santos, Hertdweck, Haider, Romäo and Santos2000; Günyar et al., Reference Günyar, Zhou, Drees, Baxter, Bassioni, Herdtweck and Kühn2009). We have reported, over the years, the synthesis of several complexes with bypiridil ligands and studied, under homogeneous and heterogeneous conditions, their properties as oxygen atom transfer agents (Paez et al., Reference Paez, Castellanos, Martinez, Ziarelli, Agrifoglio, Paez-Mozo and Arzoumanian2008; Arzoumanian et al., Reference Arzoumanian, Castellanos, Martínez, Paez-Mozo and Ziarelli2010; Castellanos et al., Reference Castellanos, Martínez, Páez-Mozo, Ziarelli and Arzoumanian2012) Their ability to participate in catalytic oxidation has been reported in the selective oxidation of phosphines, arylalkanes and the photochemical oxidative decomposition of persistent organic pollutants (POPs) specifically using molecular O2 as oxygen atom donor under visible light irradiation (Paez et al., Reference Páez, Lozada, Castellanos, Martínez, Ziarelli, Agrifoglio, Paez-Mozo and Arzoumanian2009; Bakhtchadjian et al., Reference Bakhtchadjian, Tsarukyan, Barrault, Martinez, Tavadyan and Castellanos2011; Castellanos et al., Reference Castellanos, Martínez, Lynen, Biswas, Van Der Voort and Arzoumanian2013). In this work we report the synthesis and results on the molecular characterization (FTIR, NMR) and X-ray powder diffraction data for the compound dichlorodioxido (4,4-dimethoxycarbonyl-2,2-bipyridyl) molybdenum(VI).
II. EXPERIMENTAL
A. Synthesis
The ligand 4,4′-dimethoxycarbonyl-2,2′-bipyridyl was previously synthesized according to the literature procedure (Arzoumanian and Bakhtchadjian, Reference Arzoumanian and Bakhtchadjian2006). CH2Cl2 solution containing 2.57 mmol of 4,4′-dimethoxycarbonyl-2,2′-bipyridyl (0.7 g) was added over a slenchk containing 3 mmol of solid MoO2Cl2. We observed the gradual disappearance of the solid and change in coloration of the solution (light green) after 3 h of reaction. The solution was filtered and the product was precipitated with ethyl ether to give a light green solid with yield of 85%. Its synthesis is shown in the Figure 1. The density of 1.604 g cm−3 was measured by the flotation method in an aqueous solution of potassium iodine.
![](https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20160921025304527-0954:S0885715613000754:S0885715613000754_fig1g.gif?pub-status=live)
Figure 1. Synthesis of 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene.
The molecular characterization which was carried out with ultraviolet–visible (UV–Vis) spectroscopy showed two absorption bands in the regions 230–300 and 310–379 nm. Infrared (IR) spectrometry showed stretching vibrations; ν: 1727 (C = O); 1434 (C = C); 944, 911 (Mo = O); and nuclear magnetic resonance on protons (1H NMR, 400 MHz, CDCl3) showed δ (ppm) = 9.73 (d, 2H), 8.92 (s, 2H), 8.30 (d, 2H), 4.16 (t, 6H).
B. Powder data collection
A small portion of the title compound was gently ground in an agate mortar and sieved to a grain size less than 38 µm. The specimen was mounted on a polymethyl methacrylate (PMMA) specimen holder. The XRPD pattern was recorded with a D8 ADVANCE BRUKER diffractometer operating in DaVinci geometry equipped with a Cu-target X-ray tube (40 kV and 30 mA), a nickel filter and a 1-dimensional LynxEye detector. A receiving slit (RS) of 0.6 mm and primary and secondary soller slits (SS) of 2.5° were used. The scan range was 2–70° 2θ with a step size of 0.015 26° and a count time of 2 s per step. Powder data were collected at room temperature (298 K).
Powder analytical software was used to remove the background (Sonneveld and Visser, Reference Sonneveld and Visser1975), smoothing (Saviztky and Golay, Reference Saviztky and Golay1964), to eliminate the Kα 2 component (Rachinger, Reference Rachinger1948) and the second derivative method was used to determine the position and intensities of the diffraction maxima from each reflection.
III. RESULTS AND DISCUSSION
The X-ray powder pattern of the compound dichlorodioxido(4,4-dimethoxycarbonyl-2,2-bipyridyl)molybdenum(VI) (2) is shown in Figure 2. X-ray powder diffraction data for the compound (2) are given in the Table I. All reflections were indexed successfully using the DICVOL06 program (Boultif and Louër, Reference Boultif and Loüer2004) on a monoclinic unit cell and the peak positions, each with an absolute error of 0.03° (2θ), were used in the calculations. The space group, P21/c (No. 14), estimated by the program CHEKCELL (Laugier and Bochu, Reference Laugier and Bochu2002) was compatible with the systematic absences and with the crystal density. The unit-cell parameters of the compound (2) were refined with the program NBS*AIDS83 software (Miguell et al., Reference Miguell, Hubberd and Stalick1981). Its crystal data, X-ray density and figures of merit M20 (de Wolff, Reference de Wolff1968) and F20 (Smith and Snyder, Reference Smith and Snyder1979) are compiled in the Table II.
![](https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20160921025304527-0954:S0885715613000754:S0885715613000754_fig2g.gif?pub-status=live)
Figure 2. Powder X-ray diffraction pattern of 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene.
Table I. X-ray powder diffraction data of 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene. Cu-Kα1 radiation (λ = 1.5406 Å).
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Table II. Parameters obtained by X-ray powder diffraction for the compound 1-[N-(methyl)-(3,5-dimethylphenylamino)]methylnaphthalene.
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ACKNOWLEDGEMENTS
The authors would like to thank Centro de Investigaciones of Universidad Santo Tomás (Bucaramanga-Colombia) for their support with the project approved in the VII internal call of research projects and the Laboratorio de Difracción de Rayos-X PTG of Universidad Industrial de Santander (Bucaramanga-Colombia) for data collection.