(Phenyliodosyl)benzene tosylate dihydrate

The title compound is a λ5-diaryliodosyl salt capable of sulfide oxidations.


Structure description
The crystal structure of (phenyliodosyl)benzene tosylate dihydrate (1) is shown in Fig. 1. A partial packing structure is shown in Fig. 2. The title compound 1 crystallizes from water via slow cooling to 293 K to the monoclinic crystal system with space group P2 1 /c. This iodosyl salt arose from the reaction of iodoxybenzene with sodium hydroxide (Fig. 3). The intermediate formed was captured with p-toluene sulfonic acid, generating 1.
Zhdankin synthesized a tosylate derivative of 2-iodoxybenzoic acid. Crystals of the final product could not be isolated, but the intermediate mixed tosylate-acetate derivative was analysed. The I-O bond lengths in this iodine(V) compound had distances of 2.080 (2), 2.213 (2), 2.027 (2) and 1.998 (2) Å (Yusubov et al., 2013). These values are in accordance with a single-bond interaction of iodine with oxygen, further indicating that the I-O bond distance in 1 is of a double-bond nature. Additionally, bond lengths being shorter than predicted in hypervalent iodine compounds have been studied previously (Koser et al., 1976). Koser confirmed the I-O single bond length was shorter (1.91 Å ) than the computed distance (1.96 Å ) in his seminal work on hydroxy(tosyloxy)iodobenzene. Additionally, in 1, secondary coordination of the iodonium I-oxide centre with neighbouring water molecules indicates a close contact via the I1Á Á ÁO2 and I1Á Á ÁO3 with bond distances of 2.5674 (10) and 2.8118 (10) Å , respectively.
The title compound forms a distorted octahedral geometry in accordance with comparison to a VSEPR model. The O1-I1-O2 bond angle of 175.27 (4) , the C7-I1-O3 angle of 176.33 (4) , the O1-I1-O4 angle of 77.55 (4) with the coordinating tosylate anion and the C1-I1-C7 angle of 95.36 (4) complete the distorted octahedral geometry. The accompanying tosylate anion and water molecules occupy apical and equatorial positions to stabilize the monomeric complex. Bis(diphenyliodonium I-oxide) diacetate trihydrate also adopted a distorted octahedral geometry, albeit via a dimeric coordinating structure (Bozopoulos & Rentzeperis, 1987). In this complex, the asymmetric units form distorted trigonal-pyramidal arrangements, where the iodine atoms occupy the apices, resembling the IO 3 À iodate anion. Secondary IÁ Á ÁO interactions complete the distorted octahedral geometry around each individual iodine atom. The title complex 1 does not dimerize like the Rentzeperis compound, most likely due to the bulky nature of the coordinating tosylate anion, along with additional hydrogen bonding of the sulfone O atoms and water O atoms with neighbouring water molecules.

Figure 1
The title compound 1 with 50% displacement ellipsoids. All hydrogen labels are omitted for clarity.

Figure 2
The unit cell as viewed down the a axis showing intermolecular hydrogen bonds as dashed lines. and then cooled to room temperature. To the cooled reaction flask were added 50 ml of ice-cold water, and the white crystals that formed were filtered, washed with cold water (20 ml), cold chloroform (10 ml), and air-dried in a dark room until a constant weight was found (2.08 g, 8.81 mmol, 88% yield). The crude material was used in the next step without further purification. The iodoxybenzene (2.08 g, 8.81 mmol) was added to a stirred solution of 1 N NaOH (18.7 ml) pre-cooled to 277 K. The reaction was stirred for 1 h maintaining the temperature of the reaction below 281 K. The NaIO 3 that formed was filtered off. The filtrate was poured into a roundbottomed flask equipped with a magnetic stir bar and cooled to 277 K. With vigorous stirring p-toluene sulfonic acid monohydrate (2.87 g, 15.08 mmol) was added to the cooled filtrate and a white precipitate formed. The suspension was stirred for an additional 30 min and then filtered. The compound was washed with a minimal amount of diethyl ether (10 ml) and ice-cold water (10 ml). The product (1.75 g, 3.47 mmol, 47.5% yield) matched known 1 H, 13 C and FTIR data (Chen, 2007). A sample for crystallographic analysis was prepared by dissolving the sample in a minimal amount of boiling water and allowing for slow cooling in an insulated thermal bath, insuring that the temperature took at least two days to return to room temperature. After additional cooling at room temperature for four days, the crystals that formed were suitable for X-ray analysis.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.