CS⋯I halogen bonding interactions in crystalline iodinated dithiole-2-thiones and thiazole-2-thiones

Abstract

The propensity of the sp 2 sulfur atom in thiones to act as a halogen bond (XB) acceptor is well established with dihalides (I 2 , IBr or ICl) as XB donors, but has been more rarely explored with organic XB donors. The crystal structures of four iodinated heterocycles, namely, the mono-and diiodo derivatives of 1,3-dithiole-2-thione and N-ethylthiazole-2-thione, offer an opportunity to evaluate the strength and directionality of such C-I⋯S interactions. We describe here the original synthesis of 3-ethyl-5-iodothiazole-2IJ3H)-thione and 3-ethyl-4,5-diiodothiazole-2IJ3H)-thione and the solid state structures of the four compounds, with specific attention to the halogen bonds (C-I⋯SC) and hydrogen bonds (C-H⋯I,S) taking place in the crystals, in connection with the peculiarities of the calculated electrostatic surface potential (ESP) of the four molecules. The thione sulfur atoms in thiazole-2-thiones appear as better XB acceptors than in dithiole-2-thiones, with a notable deformation of the charge concentration area. The mono-iodinated derivatives, 4-iodo-1,3-dithiole-2-thione and 3-ethyl-5-iodothiazole-2-thione, are characterized by hydrogen atoms with positive extremum of the electrostatic surface potential comparable to those of the neighboring iodine atoms, illustrating the parallelism between C-I⋯S halogen bonds and the so-called weak C-H⋯I,S hydrogen bonds. CrystEngCommThis journal is

The Halogen Bonding Proclivity of the sp3 Sulfur Atom as a Halogen Bond Acceptor in Cocrystals of Tetrahydro-4H-thiopyran-4-one and Its Derivatives

“…Simple comparisons with literature data for other types of acceptor sulfur atoms (thione, thiocyanate, or thioamide) show that these halogen bonds feature comparable or slightly higher upper limits on R.S. values (albeit at lower temperatures) to those in this work (6.0–17% for thiones, 43 , 45 , 46 7.6–17% for thioamides, 47 , 48 and 5.8–16.4% for thiocyanate species 39 − 42 , 57 ), as well as that the more exposed sulfur atoms or ions can participate in multiple halogen and hydrogen bonds. This apparent disadvantage of the hindered cyclic sp 3 sulfur can also be considered an advantage, because it could have less propensity for hydrogen bonding.…”

Halogen Bonding between Thiocarbonyl Compounds and 1,2- and 1,4-Diiodotetrafluorobenzenes

“…Much of the recent XB research on the donor systems has concentrated on nonperfluorinated iodine based XB donors like iodonium (I + ), − I 2 , − and tetraiodoethylene. , On the XB acceptor side, a large part of the recent XB research has been focused on nitrogen compounds, although other XB applications, such as anion recognition, ,− have been actively researched and shown to be useful, e.g., as analytical tools. Out of the other possible XB acceptors, neutral sulfur species have attracted relatively little attention, but, for example, two studies on weak XBs of the title thiocarbonyl compounds were recently reported. , …”

Single-handed supramolecular double helix of homochiral bis(N-amidothiourea) supported by double crossed C−I···S halogen bonds

“…The double C−I···S halogen bonds are the same in structural parameters (Supplementary Table 3), being 3.764(3) Å in length that is shorter than the sum of the van der Waals radii of I and S atoms (3.780 Å) 33 , whereas the angle of the halogen bond is 156.3(3)°, being almost linear. The bond length is longer than the usual I···S contacts, such as those in crystalline iodinated dithiole-2-thiones and thiazole-2-thiones that range from 3.2 to 3.4 Å 27 , but it is comparable to those in the classic crystals of I-substituted tetrathiafulvalene derivatives with I 3 − or I 2 that range between 3.7–3.9 Å 28 . The longer length observed here may result from the balance of the bond lengths and angles, since shorter lengths will lead to smaller angles in the crossed geometry with two I···S contacts.…”