Organoselenium compounds containing pyrazole or phenylthiazole groups: Synthesis, structure, tin(IV) complexes and antiproliferative activity

Abstract

The diorganodiselenides (pzCH 2 CH 2 ) 2 Se 2 (1) and (PhtzCH 2 ) 2 Se 2 (2) were prepared by reacting Na 2 Se 2 with 1-(2-bromoethyl)-1H-pyrazole and 4-(chloromethyl)-2-phenylthiazole, respectively, while the reactions between 1-(2-bromoethyl)-1H-pyrazole or 4-(chloromethyl)-2-phenylthiazole and the lithium organoselenolates [2-(Et 2 NCH 2 )C 6 H 4 ]SeLi and [2-{O(CH 2 CH 2 ) 2 NCH 2 } C 6 H 4 ]SeLi in a 1:1 molar ratio resulted in the heteroleptic diorganoselenium(II) compounds [2-(Et 2 NCH 2 )C 6 H 4 ](R)Se (R = pzCH 2 CH 2 (3) or PhtzCH 2 (5)) and [2-{O(CH 2 CH 2 ) 2 NCH 2 }C 6 H 4 ](R)Se (R = pzCH 2 CH 2 (4) or PhtzCH 2 (6)). The diorganotin(IV) bis(organoselenolato) derivatives of type R 2 Sn(SeCH 2 CH 2 pz) 2 (R = 2-(Me 2 NCH 2 )C 6 H 4 (7) or Me (8)) were obtained by reacting (pzCH 2 CH 2 ) SeNa with the appropriate diorganotin(IV)dichloride in a 2:1 molar ratio. All compounds were investigated using NMR spectroscopy ( 1 H, 13 C, 77 Se, 119 Sn as appropriate) and ESI+ mass spectrometry. The molecular structures of 2 and 6 were determined using single-crystal X-ray diffraction. The formation of a 10-Se-3 hypercoordinated species was evidenced for 6 in the solid state, as a consequence of the C,N coordination behaviour of the 2-{O(CH 2 CH 2 ) 2 NCH 2 } C 6 H 4 group. Compounds 1, 7 and 8 were investigated for their antiproliferative activity towards the mouse colon carcinoma C26 cell line with the preliminary results showing a better activity than 5-fluorouracil.

On the Importance of σ–Hole Interactions in Crystal Structures

“…Particularly, many studies demonstrate the ability of organic diselenides to establish both intermolecular and intramolecular ChBs with electron-rich atoms, which are stronger and more directional (see Table 6 for geometrical details) in the prolongation of the Se-Se bond [9]. Two examples are shown in Figures 11 and 12, the first one illustrating ChBs in the prolongation of the diselenide bond (FEYBAP [107]). In Figure 12, the HOGBOW [108] crystal architecture is shown, exhibiting ChBs in the middle of the Se-Se bond, because of the overlapping of both σ-holes.…”

Chalcogen bonding in crystalline diselenides and selenocyanates: From molecules of pharmaceutical interest to conducting materials

“…Among the acyclic diselenides, only a few examples of intermolecular ChB interactions with Lewis bases are found, indicating already that these interactions do not play an important role in these highly flexible molecules. The thiazole derivative23 (Table 2: FEYBAP) provides an…”

Heterovalent chalcogen bonding: supramolecular assembly driven by the occurrence of a tellurium(ii)⋯Ch(i) (Ch = S, Se, Te) linkage

“…Fourmigué and Dhaka 18 queried the Cambridge Structural Database (CSD) for ChBs present in organic diselenides, R 2 Se 2 , and found a few Se I ⋯Ch II (Ch = S II , Se II ) linkages in which formally monovalent selenium(I) centers function as ChB donors, providing a σ-hole for interactions with a Ch II -based nucleophilic center. Heterovalent ChB, however, was beyond the scope of the original synthetic studies [42][43][44] and also of the review. 18 Our own CSD search (section 4.6) revealed the structure of the ditellurole Te I 2 (CH t Bu) 2 Te II (CSD refcode: COWQUB, Fig.…”