Synthesis and Crystal Structure of Hexahydrobis[(1,3-p-dimethylaminobenzyl)-1,3-diazepine]-2-selenone, C23H32N4Se

Abstract

The use of exobycyclic alkenes of the type 1 (m = 2 or 3) as sources of N-heterocyclic carbene complexes of transition metals is well-established. 1 However, larger rings, i.e. m ≥ 4, have so far not been tackled. In an effort to fill the gap, we prepared 1c (R = p-CH2C6H4NMe2; the R group was chosen so as to contain a quaternizable -NMe2 functionality which would increase the water solubility). Under mild conditions, 1c reacted with Group VI elements to give cyclic chalcogeno ureas (Eq. (1)). This behavior is typical of reactive tetraaminoalkenes 1a and 1b. 2,3 In sharp contrast, 1c is inert to electrophilic transition metal complexes such as [RuCl2(η 6 -arene)]2. This remarkable difference aroused our curiosity. Therefore, the Xray structure of the seleno urea 2c, derived from the alkene 1c was determined.In a typical reaction, bis[1,3-bis(p-dimethylaminobenzyl)-hexahydro-1,3-diazepine-2-ylidene] (1c: 0.886 g, 1.00 mmol) was heated with elemental selenium (0.200 g, 2.53 mmol) in refluxing toluene (20 mL) for 2 h. The resulting solution was cooled to room temperature and then filtered to remove the excess selenium. The volume of the filtrate was reduced to ca. 10 mL and hexane (10 mL) was added. Upon cooling the solution to -20˚C, we obtained cream crystals of the title compound (0.54 g, 61%, m.p. = 141 -142˚). All reactions were carried out under argon atmosphere with the use of Schlenk techniques. The solvents were dried and deoxygenated by standard procedures. The new compound exhibited satisfactory spectroscopic and analytical data. 112.4, 125.0, 129.6, 150.0 CH2C6H4NMe2, 192.8 (C=Se). Anal. Calcd. for C23H32N4Se: C, 62.29; H, 7.27; N, 12.63; found: C, 60.15; H, 7.30; N, 12.39.The crystal and molecular structures of C23H32N4Se were determined by single crystal X-ray diffraction. The crystal data, details of the data collection and the structure determination are given in Table 1. The chemical reaction of the title compound is shown in Fig. 1. The structure was solved by direct methods and refined by full-matrix least squares. The non-hydrogen atoms were refined anisotropically. The diazepine ring proved to be disordered over two orientations. The site-occupancy of the major disordered component refined to 0.53(1). The relatively high R values are related to the weak scattering that is most probably a consequence of the disorder in the diazepine ring. H atoms were added at calculated positions and refined using a riding model with In the title compound, C23H32N4Se, was synthesized and its crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in orthorhombic system, space group Pbca, a = 10.9960(10)Å, b = 14.9460(9)Å, c = 27.565(5)Å and Z = 2. According to X-ray crystallographic studies, the diazepine ring is observed to be in a disordered state. The site-occupancy of the major compenent refined to 0.53(1). The C=Se bond length of 1.862(4)Å is a double bond character. The dihedral angle between the two phenyl rings is 37.7(2)˚.

Ferrocene‐Based N‐Heterocyclic Carbenes with Functionalised Benzyl Substituents

“…The only structurally characterised selenourea compound derived from an expanded‐ring NHC contains a seven‐membered ring 33. The crystal structures of 4a Se (Figure 7) and 4b Se (Figure 8) are the first examples of cyclic selenourea compounds with a six‐membered ring.…”

The Investigation of the Antioxidative Properties of the Novel Synthetic Organoselenium Compounds in Some Rat Tissues

“…Novel synthetic organoselenium compounds (SeI and SeII) (Fig. 1A and B) were synthesized in our laboratories by methods found in the literatures (15,16). The novel compounds synthesized were characterized by 1 H-NMR (300 MHz), 13 C-NMR (75.5 MHz), and FT-IR spectroscopic techniques and microanalysis.…”

Role of Synthesized Organoselenium Compounds on Protection of Rat Erythrocytes from DMBA-Induced Oxidative Stress

“…The synthetic organoselenium compounds (Se I and Se II ; Fig 1a, b) were synthesized in our laboratories by methods prepared in the literature [15][16][17]. The compounds synthesized were characterized by 1 H-nuclear magnetic resonance (NMR; 300 MHz), 13 C-NMR (75.5 MHz), Fourier transform infrared spectroscopic techniques, and microanalysis.…”