Heterocyclic bismuth(III) compounds with transannular S→Bi interactions. An experimental and theoretical approach

Accepted Manuscript Heterocyclic bismuth(III) compounds with transannular S→Bi interactions. An experimental and theoretical approach Ana Toma, Ciprian I. Raţ, Anca Silvestru, Tobias Rüffer, Heinrich Lang, Michael Mehring PII:

S0022-328X(16)30019-5

DOI:

10.1016/j.jorganchem.2016.01.019

Reference:

JOM 19370

To appear in:

Journal of Organometallic Chemistry

Received Date: 7 November 2015 Revised Date:

1 January 2016

Accepted Date: 13 January 2016

Please cite this article as: A. Toma, C.I. Raţ, A. Silvestru, T. Rüffer, H. Lang, M. Mehring, Heterocyclic bismuth(III) compounds with transannular S→Bi interactions. An experimental and theoretical approach, Journal of Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.01.019. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Graphical Abstract

Text

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Several hypervalent diorganobismuth(III) compounds of type [(C6H4CH2)2S]BiX [X = Br (1), I (2), ONO2 (3) and OSO2CF3 (4)] were prepared and structurally characterized. The S→Bi intramolecular coordination is evaluated both at experimental and

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theoretical level and the polymeric associations in crystals are discussed.

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Figure

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Heterocyclic bismuth(III) compounds with transannular S→Bi interactions. An experimental and theoretical approach. Ana Toma,a Ciprian I. Raț,a * Anca Silvestru,a * Tobias Rüffer,b Heinrich Lang b and Michael

a

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Mehring c * Faculty of Chemistry & Chemical Engineering, Chemistry Department, Babes-Bolyai

University, RO-400028 Cluj-Napoca, Romania; E-mail: [email protected] b

Technische Universität Chemnitz, Institut für Chemie, Anorganische Chemie, D-09107

Chemnitz, Germany; E-mail: [email protected]

Technische Universität Chemnitz, Institut für Chemie, Koordinationschemie, D-09107

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c

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Chemnitz, Germany, E-mail: [email protected]

Abstract

Several new diorganobismuth(III) compounds based on a butterfly-like tetrahydrodibenzo[c,f][1,5]thiabismocine heterocyclic framework were prepared and structurally

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characterized. The reaction between the dilithio derivative of bis(2-bromobenzyl)sulfane with BiBr3 in a 1:1 molar ratio resulted in the formation of [(C6H4CH2)2S]BiBr (1). Further exchange reactions of 1 with KI, AgNO3 and AgOSO2CF3, respectively, afforded the hypervalent species [(C6H4CH2)2S]BiX [X = I (2), ONO2 (3) and OSO2CF3 (4)]. The new

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species were characterized by 1H and

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C NMR, FT IR spectroscopy and mass spectrometry.

The crystal and molecular structures of compounds 1 ‒ 4 were determined by single-crystal X-

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ray diffraction. In all compounds the sulfur atom is strongly intramolecularly coordinated to bismuth, thus resulting in hypervalent species 10-Bi-4 (for 1 and 2) and 12-Bi-5 (for 3 and 4). Intermolecular interactions (X···Hmethylene in 1 and 2, Bi···Cg in 3 and Bi···O in 4) led to polymeric chains in the crystals. DFT calculations were carried out on [(C6H4CH2)2S]BiCl and 1 – 4 in order to better understand the S→Bi intramolecular coordination.

Keywords:

organobismuth(III) heterocycles; spectroscopy; single crystal X-ray diffraction;

DFT calculations; hypervalency.

ACCEPTED MANUSCRIPT 1.

Introduction During last years a continuously increased interest was devoted to hypervalent

organometallic compounds of main group elements due to their potential as catalysts in various organic transformations, precursors for nanomaterials or as biologically active species [1,2]. By using organic groups with donor atoms (O, S, N) capable for

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intramolecular coordination not only the thermal and hydrolytic stability can be significantly increased, but also the specific properties of the designed species might be tuned according to the desired purpose. Among the heavy main group elements, bismuth is very attractive due to several characteristics: (i) it has a low level of

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toxicity, (ii) its compounds are readily available, (iii) it is able to form air-stable organometallic species, (iv) a majority of its compounds are Lewis acids of moderate to high strength and (v) it is relatively cheap comparing with the late d metals which

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are currently used in catalysis or medicine [3-7]. Molecular bismuth compounds, either inorganic or intramolecularly stabilized organometallic species were studied in relation with their catalytic activity [8-10]. It is well known that the catalytic properties of a given species are strongly influenced by the Lewis acidity and the availability of the metal centre for the organic substrate activation [11,12]. During last years bifunctional

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species which combine the Lewis acidity of the metal with the Lewis basicity of the ligand were developed and different strategies were employed in order to design new catalysts with increased diastereoselectivity, taking in account the nature and the space-structure of the ligand as well as the effect of the counter ion [13]. Sulfur

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bridged bis(phenolato) ligands correspond to these requirements and several compounds based on a tetrahydrodibenzo[c,f][1,5]thiabismocine framework were

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reported as active species in the direct diastereoselective Mannich reaction [14,15], or for the stereoselective synthesis of (E)-α,β-unsaturated ketones [16]. On the other hand organobismuth compounds were investigated due to their

antibacterial

[17,18]

and

antitumor

activity

[19-21].

Bi-

chlorotetrahydrodibenzo[c,f][1,5]thiabismocine and related heterocyclic compounds have shown a pronounced antimicrobial activity against several strains of bacteria [22] and anticancer potential in various human cancer cell lines, e.g. the leukemia cell line HL-60 [23]. In order to bring new insights to the influence which might arise upon the strength of the S→Bi intramolecular interaction by using different anionic ligands attached to bismuth in heterocyclic tetrahydrodibenzo[c,f][1,5]thiabismocines, we prepared and we investigated

ACCEPTED MANUSCRIPT compounds 1 - 4. In addition to the experimental analysis of their structures both in solution and in solid state, DFT calculations were carried out on [(C6H4CH2)2S]BiCl and 1 – 4. The intramolecular coordination of the sulfur to the bismuth atom was analysed within the framework of the NBO method.

2.1.

Results and discussion Preparation and spectroscopic characterization

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2.

The diorganobismuth(III) compounds 1 – 4, based on a butterfly-like tetrahydrodibenzo[c,f][1,5]thiabismocine heterocyclic framework, were prepared according to Scheme

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1. The bromo-derivative 1 was obtained by the ortho-lithiation of bis(2-bromobenzyl) sulfane, followed by the reaction of the dilithio derivative with BiBr3 in a 1:1 molar ratio. Further exchange reactions between 1 and the appropriate potassium or silver salt led to

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compounds 2 – 4.

Scheme 1. Synthesis of compounds 1 – 4.

The new compounds are colourless, air-stable microcrystalline solids with moderate solubility in common organic solvents. As it was previously observed also for the chlorine homologue, the effect of the strong transannular S→Bi interaction significantly increases the thermal and hydrolytic stability of these compounds [24].

ACCEPTED MANUSCRIPT The 1H and

13

C NMR spectra of 1 – 4 are consistent with the proposed

structure. By contrast with the free dibenzylthioether, where the CH2 protons give a singlet resonance, in the diorganobismuth complexes 1 - 4 the CH2 protons appear as AB spin systems, at low field shifted, similarly as in the previously reported derivative [(C6H4CH2)2S]BiCl [24]. The APCI+ mass spectra for the reported species show the

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base peak for the cation [{(C6H4CH2)2S}Bi+] at m/z 421.05. The FT IR spectrum of compound 3 shows strong bands at 1448 and 1430 cm−1, characteristic for the νasNO2 stretching vibration [25], while in the spectrum of compound 4 the bands at 1293, 1171 and 1010 cm−1 were assigned to the νasSO2, νsSO2 and νSO vibrations, respectively [26].

This behavior suggests an unisobidentate coordination of the

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anionic ONO2− and OSO2CF3− ligands, as it was also observed by single-crystal X-ray

2.2.

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diffraction (see subsequent discussion).

Single-crystal X-ray diffraction studies

Single crystals of compounds 1 – 4 suitable for X-ray diffraction studies were obtained from a CH2Cl2/n-hexane (1/5, v/v) mixture of solvents at ambient temperature. The crystals of the diorganobismuth(III) bromide 1 and the diorganobismuth(III) iodide 2 contain

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four and respectively two similar independent molecules in the asymmetric unit. Thermal ellipsoids representations of the compounds are depicted in Figures 1 – 4 and the relevant interatomic distances and angles are given in Tables 1 and 2. Carbon atoms in Table 1 were

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labelled according to Scheme 2.

Figure 1 Figure 2 Figure 3 Figure 4

Scheme 2. Labelling scheme for the [(C6H4CH2)2S]Bi fragment.

Table 1

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In all compounds intramolecular transannular S→Bi interactions are present, thus giving rise to a distorted pseudo-trigonal bipyramidal coordination geometry about bismuth, with the coordinated sulfur S1 and the halogen atoms (in 1 and 2) or

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O1 (in 3 and 4) in apical positions and the aryl carbon atoms C1 and C14 and the lone pair in the equatorial plane. The S→Bi interaction determines the formation of 10-Bi-4 hypervalent species [27] with a butterfly-like structure.

The S→Bi interactions in 1 [range 2.830(5) – 2.836(5) Å] and 2 [2.847(3) and

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2.861(4) Å] are close to those observed in the related {(C6H4CH2)2S]BiCl [range 2.845(4) – 2.859(4) Å, in the four independent molecules] [24]}, while in the other two derivatives the respective S−Bi bond distances are shorter, 2.764(3) Å in 3 and

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2.6741(17) Å in 4. The latter values are close to those observed in the cationic species [S(CH2C6H4)2Bi(OH2)]+ (2.692(3) – 2.713(1) Å) [15]. The S−Bi−X (X = Br, O) bond angles in the range 155.4(2) – 158.28(12)° for compounds 1, 3 and 4 are similar with those found in the corresponding chloride [24], or the cationic species containing coordinated water [15], while in case of the iodide 2 the values observed in the two

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independent molecules are larger (163.24(8) and 167.19(7)°). In compounds 3 and 4 short intramolecular Bi···O2 contacts are also present (3.041(11) Å in 3 and 3.568(5) Å in 4, vs. ΣrvdW (Bi,O) 3.80 Å) [28], thus being consistent with an asymmetric bidentate coordination of the ONO2 and OSO2CF3 anionic ligands. If we take in account also

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theses contacts and the increased coordination number of the metal, compounds 3 and 4 might be described as 12-Bi-5 hypervalent species. The proximity of the electron-

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donating O2 atoms in these compounds might be responsible for the strengthening of the S→Bi interaction in compounds 3 and 4 in comparison with the analogues halides. The Bi−O1 covalent bonds in compounds 3 and 4 are weaker than those observed in [S(CH2C6H4)2]BiOC(O)CH2CH2GePh3 (2.256(7) Å) [24] or in monomeric bismuth alkoxides (2.15 – 2.20 Å) [29], but close to or even greater than the values found in the cationic [S(CH2C6H4)2Bi(OH2)]+ species (2.447(7) – 2.497(6) Å) [15]. The dihedral angles between the two phenyl rings in the respective monomers (range 77.19 – 88.04°) are smaller than the corresponding C1−Bi−C14 [range 88.2(4) − 97.7(6)°] and the C7−S1−C8 angles [range 100.3(10) – 103.0(3)°] and much smaller than the respective dihedral angle of 101.2° in [S(CH2C6H4)2]BiCl [15]. In compounds 1 − 3, the five-membered rings Bi1C1C6C7S1 (1) and Bi1C14C9C8S1 (2) are not planar,

ACCEPTED MANUSCRIPT but folded along the C7···Bi1 and C8···Bi1 axes, respectively. As a consequence the structures of these species might be described in terms of planar chirality [30] as mixtures of S1,S2 and R1,R2 isomers (the superscripts “1“ and “2“ refer to the two fivemembered rings, as designated above). In compound 4 the Bi1C1C6C7S1 system is almost planar (S1 deviation from the Bi1C1C6C7 best plane is 0.084 Å), while the S1

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atom is 0.269 Å out of the Bi1C14C9C8 best plane. Thus, for compound 4 a mixture of S2 and R2 isomers might be considered.

A closer look at the crystal packing of the four compounds shows the formation of supramolecular structures based on different types of intermolecular interactions, as

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followings:

- the bromide 1 has a similar crystal packing as the previously described chloride. In the crystal one-dimensional polymeric chains of Bi1/Bi3 and Bi2/Bi4 molecules, based on

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short Br···Hmethylene contacts (range 2.639(2) – 2.743(2) Å; c.f. ΣrvdW(Br,H) 3.15 Å) [28], are developed along the a and b axes (see ESI†, Figures S1 and S2). If additional weak Br···Hmethylene contacts in the range 2.904(2) – 3.064(2) Å, involving the other methylene proton of the same SCH2 group and the bromine of the neighboring polymeric chain growing in the same direction are considered as well, results a supramolecular network built of

S3).

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successively ordered layers of Bi1/Bi3 and Bi2/Bi4 interconnected chains (see ESI†, Figure

- the crystal of iodide 2 consists also of one-dimensional infinite polymeric chains of Bi1 molecules connected by short I···Hmethylene contacts (I1···H8A' 2.9663(2)

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Å, vs. ΣrvdW(I,H) 3.35 Å) [28] constructed in the same way as the above described chains of 2. The Bi1 molecules are further interacting with the Bi2 molecules by weak

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H···I contacts (I2''···H5 3.1934(3) Å) (Figure 5).

Figure 5

The so formed chains are connected in a supramolecular two-dimensional

network by additional weak I···H contacts established between hydrogen atoms in the phenyl ring of the Bi1 molecule and the iodine atoms in the Bi2 molecules [I1···H22A'' 3.2787(1); I2···H3''' 3.2374(2) Å, see ESI†, Figure S4]. - in the crystal of compound 3 the molecules are associated in polymeric chains by Bi···Cg intermolecular contacts (Bi-π interaction) established between the metal

ACCEPTED MANUSCRIPT atom with two adjacent molecules (Bi···Cg 3.5317(3) and 3.6507(3) Å), as depicted in Figure 6.

Figure 6

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These values correspond well with the calculated and experimental data reported previously for organobismuth compounds bearing ligands of low electron withdrawing character [31]. The crystal lattice contains CH2Cl2 molecules which connect the polymeric chains in a 2D network by weak HCH2Cl2···Cg (2.442 and 2.773 Å) and

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Cl2···H8B (2.8051(2) Å) secondary interactions (see ESI†, Figure S5).

- in the crystal of compound 4 the polymeric chain is formed by bridging

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triflate (Bi1···O3' 3.086(1) Å, Figure 7).

Figure 7

If additional intermolecular contacts in the range of the sum of the respective van der Waals radii are taken into account, Bi1···Cg2'' and H8A···O2''', a 2D supramolecular

2.3.

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network might be considered in this case also (see ESI†, Figure S6).

Theoretical calculations

Theoretical calculations at DFT level were carried out on compounds 1 ‒ 4, as

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well as on the previously reported derivative [(C6H4CH2)2S]BiCl [15]. A comparison between bond lengths and bonding angles around the metal centre is found in Table

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S1, ESI†. Visual representations of the overlapped calculated and determined molecular structures are shown in Figures S7 – S11, ESI†. In the calculated structures the Bi···S bond lengths are slightly larger (in the

range 4.01 to 6.47%) than those found in the structures determined by single-crystal X-ray diffraction. Values slightly larger were also found for Bi‒X (in 1 and 2) and Bi‒O bond lengths (in 3 and 4). The calculated bonding angles, with few exceptions, have relative deviations smaller than 5% with respect to those found experimentally. Overall, the largest differences between the calculated and determined molecular structures were found for compound 4, due to a different arrangement of the triflate ligand (see Figure S11, ESI†).

ACCEPTED MANUSCRIPT Wiberg indexes (Tables S4 and S5) corresponding to the Bi‒S interactions decrease in the series 4 > 3 > [(C6H4CH2)2S]BiCl > 1 > 2 and are consistent to the trend observed in the X-ray determined bond lengths. The Wiberg indexes of the Bi−X bonds increase in the above series. The natural charge (ESI†, Tables S4 and S5) on the bismuth atom calculated with NBO decreases as Bi‒S Wiberg indexes, with the largest

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ionic character for the Bi−X bonds corresponding to the triflate and the smallest to the iodide.

The largest stabilization energy, calculated in the second order perturbation theory analysis of the Fock matrix, results from S−Bi donation and decreases in the

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series 4 (54.59 kcal/mol) to 2 (27.32 kcal/mol). Same analysis reveals that in the case of 4, 3, and [(C6H4CH2)2S]BiCl, the donation from the S lone pair takes place in unfilled valence lone-pair with mainly p character on bismuth atom, whereas for 1 and

3.

Experimental

3.1.

Materials and methods

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2 it takes place in a Bi−X antibonding orbital.

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Starting materials were commercially available or were prepared according to literature procedures: bis(2-bromobenzyl)sulfane [24]. Organic solvents were dried and distilled prior to use. Experiments involving air sensitive compounds were carried out under argon atmosphere. Elemental analyses were performed on a Flash EA 1112

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analyzer. Melting points were measured on an Electrothermal 9200 apparatus and are not corrected. 1H,

13

C and

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F NMR spectra were recorded in CDCl3 with Bruker 500

and Bruker Avance III 400 instruments. The chemical shifts are reported in δ units

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(ppm) relative to TMS (1H and

13

C) and CFCl3 (19F). The NMR data were processed

using the MestReNova software [32]. APCI+ mass spectra were recorded on a Thermo Scientific Orbitrap XL instrument. IR spectra were recorded in the range 4000 – 400 cm−1 on a Jasco spectrometer.

Synthesis of [(C6H4CH2)2S]BiBr (1). A solution of nBuLi in n-hexane (4.78 ml 2.5M sol., 0.766 g, 11.95 mmol) was added dropwise to a solution of bis(2-bromobenzyl)sulfane (2.224 g, 5.9 mmol) in diethyl ether (30 ml) at -30 °C. The reaction mixture was stirred at this temperature for 3h and then it was cooled at -50 °C, when solid BiBr3 (2.679 g, 5.9 mmol) was added.

ACCEPTED MANUSCRIPT After 30 min, it was allowed to gradually reach room temperature and it was left until the next day under vigorous stirring. The solvent is removed in vacuum and the solid was extracted with toluene (2 x 20 ml). The organic phase was washed with degassed water (3 x 15 ml) and then dried on MgSO4. The solvent was removed at low pressure and compound 1 was isolated as a light yellow solid. Yield: 2.01 g (67%). M.p. 188–

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191 °C. Anal. calcd. for C14H12SBiBr (501.19): C, 33.55; H, 2.41; found: C 33.35, H 2.35%. 1H NMR (500 MHz): δ 4.36, AB spin system with δA 4.23 and δB 4.49 (4H, 2

JHH = 15.2 Hz), 7.38 (t, 2H, H4, 3JHH = 7.4 Hz) 7.46 (t, 2H, H3, 3JHH = 7.3 Hz), 7.53

(d, 2H, H5, 3JHH = 7.5 Hz), 8.96 (d, H2, 2H, 3JHH = 7.5 Hz).

C NMR (126 MHz): δ

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41.06 (CH2), 128.17 (C4), 130.87 (C5), 131.33 (C3), 141.39 (C2), 147.78 (C6), 170.29

Synthesis of [(C6H4CH2)2S]BiI (2).

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(C1). MS (APCI+, CH3CN), m/z (%): 421.05 (100) [(C6H4CH2)2S]Bi+.

To a solution of 1 (0.457 g, 0.9 mmol) in CH2Cl2 (20 ml), a solution of KI (0.2 g, 0.11 mmol) in water (10 ml) was added under vigorous stirring. The organic phase became yellow and after 2 h under stirring, it was separated from the aqueous phase and dried over MgSO4. After removal of the solvent in vacuum, a crystalline yellow

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powder was obtained. Yield: 0.49 g (98%). M.p. 196 °C (dec.) Anal. calcd. for C14H12SBiI (548.19): C, 30.67; H, 2.21; found: C 30.81, H 2.26%.

1

H NMR (500

MHz): δ 4.3 AB spin system with δA 4.18 and δB 4.43 (4H, 2JHH = 14.8 Hz), 7.33-7.46 (m, br., 4H, H4 + H3), 7.47-7.54 (m, 2H, H5), 9.19 (br., 2H, H2). 13C NMR (126 MHz):

(C6),

163.92

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δ 40.93 (CH2), 128.20 (C4), 130.71 (C5), 131.80 (br., C3), 145.72 (br., C2), 147.71 (br.,

C1).

MS

(APCI+,

CH3CN),

m/z

(%):

421.05

(100)

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[(C6H4CH2)2S]Bi+.

Synthesis of [(C6H4CH2)2S]Bi(ONO2) (3). Compound 3 was obtained as a colourless solid, following a similar procedure

as the one described for compound 2, by using [(C6H4CH2)2S]BiBr (0.208 g, 0.4 mmol) and AgNO3 (0.140 g, 0.8 mmol) in acetone (10 ml),. Yield: 0.176 g (88%). M.p. 150 °C (dec.). Anal. calcd. for C14H12BiNO3S (483.30): C, 34.79; H, 2.50; N, 2.90. found: C, 34.56; H, 2.42; N, 2.81%.

H NMR (400 MHz): δ 4.53 AB spin

1

system with δA 4.39 and δB 4.67 (4H, 2JHH = 14.7 Hz), 7.38 (t, 2H, H4, 3JHH = 7.6 Hz), 7.54 (t, 2H, H3, 3JHH = 6.8 Hz), 7.63 (d, 2H, H5, 3JHH = 6.2 Hz), 8.32 (br, H2, 2H).

13

C

ACCEPTED MANUSCRIPT NMR (101 MHz): δ 42.43 (CH2), 128.27 (C4), 131.26 (C5), 131.32 (C3), 138.48 (br., C2), 148.70 (C6), the C1 resonance was not observed. MS (APCI+, CH3CN), m/z (%): 421.05 (100) [(C6H4CH2)2S]Bi+. Synthesis of [(C6H4CH2)2S]Bi(OSO2CF3) (4).

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Compound 4 was obtained following a similar procedure as that one described for compound 2, from [(C6H4CH2)2S]BiBr (0.185 g, 0.36 mmol) and AgOSO2CF3 (0.100 g, 0.38 mmol) in acetone (6 ml), as a colourless solid. Yield: 0.164 g (89%). M.p. 140 °C. Anal. calcd. for C15H12BiF3O3S2 (570.36): C, 31.59; H, 2.12; found: C, H NMR (500 MHz): δ 4.69 AB spin system with δA 4.53 and δB

1

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31.70; H, 2.20%.

4.86 (4H, 2JHH = 15.4 Hz), 7.41 (t, 2H, H4, 3JHH = 7.5 Hz), 7.61 (t, 2H, H3, 3JHH = 7.6 Hz), 7.72 (d, 2H, H5, 3JHH = 7.9 Hz), 8.38 (d, 2H, H5, 3JHH = 7.8 Hz).

13

C NMR (126

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MHz): δ 44.24 (CH2), 128.69 (C4), 131.58 (C5), 131.63 (C3), 138.45 (C2), 150.12 (C6), 183.84 (C1). The CF3 resonance was not observed.

F NMR (470 MHz): δ -77.43

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ppm. MS (APCI+, CH3CN), m/z (%): 421.05 (100) [(C6H4CH2)2S]Bi+. 3.2.

X-Ray structure determination

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Single-crystals of compounds 1 – 4 were obtained from a mixture of CH2Cl2 and n-hexane (1/5 v/v) at room temperature. The data were collected on an Oxford Gemini S diffractometer using Mo Kα radiation (λ = 0.71073 Å) at 100 K. The calculations were performed using the SHELXTL or the SHELX-97 program [33,34].

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The structures were solved by direct methods and refined by full-matrix least-square procedures on F². All non-hydrogen atoms were refined anisotropically and a riding

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model was employed in the refinement of the hydrogen atom positions. The crystals of 1 were twinned with a major domain corresponding to ca. 65%

of all reflections. The attempts to integrate the major domain with the subdomains (each containing ca. 5% of the reflections) did not lead to reliable results. The alerted unrefined electron density peaks, the low precision of C-C bonds and large final R values are most likely the consequence of the unresolved twinned nature of the crystals. Also in the structures of 3 and 4, unrefined density peaks were found in the vicinity of the bismuth atoms. Nevertheless, these peaks are known to exist at distances between 0.6 and 1.2 Å from the heavy atom and can have ca. 10% of its

ACCEPTED MANUSCRIPT electron density [35]. Intermolecular interactions were identified with PLATON [36]. The drawings were created with the Diamond software package [37].

3.3.

Computational details

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Theoretical calculations were carried out using the ORCA 3.0.3 software package [38]. B3LYP functional [39], relativistic effects via ZORA approximation [40], atom-pairwise dispersion correction with the Becke-Johnson damping scheme (D3BJ) [41], a Grid5 and the basis set def2-TZVP-ZORA were used for geometry

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optimizations [42]. The software default very tight conditions for SCF convergence with fulfilment of all convergence criteria and tight conditions for the optimizations were employed. The energy minimum of the structures obtained was confirmed by

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frequency calculations. For the NBO analysis software version 5.9 was used [43]. In order to evaluate the stabilization conferred by the S→Bi interaction, the second order perturbation theory analysis of Fock matrix in NBO basis was carried out on input files obtained from single point calculations with ORCA using BP86 functional [44] and the resolution of the identity (RI) approximation. For these single point

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calculations, besides the Ahlrichs Coulomb-fitting def2-TZVP/J basis set required for the RI, the basis set, relativistic effects and dispersion correction were those used also for the geometry optimization (vide supra), whereas for the VeryTightSCF

4.

Conclusions

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convergence criteria were considered the ORCA default values.

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Four new diorganobismuth(III) compounds of type [(C6H4CH2)2S]BiX [X = Br (1), I (2), ONO2 (3) and OSO2CF3 (4)] based on the heterocyclic butterfly-like tetrahydro-dibenzo[c,f][1,5]thiabismocine framework were prepared in order to investigate the influence of different anionic ligands with electron-withdrawing ability towards the transannular S→Bi interaction. The X-ray diffraction studies revealed that the interatomic S→Bi distance is of a similar magnitude for the diorganobismuth halides (about 2.84 Å) and decreases in the order Cl, Br, I > ONO2 > OSO2CF3. In addition, we observed that in all four species the molecules are primary associated by different types of intermolecular interactions (Br···Hmethylene in 1, I···Hmethylene in 2, π Bi···Cg in 3 and O···Bi in 4) in polymeric chains. Further weak inter-chain contacts result in supramolecular networks. NBO analysis on 1-4 and [(C6H4CH2)2S]BiCl

ACCEPTED MANUSCRIPT revealed that the strength of the intramolecular S→Bi interaction decreases in the series 4 > 3 > [(C6H4CH2)2S]BiCl > 1 > 2 and is correlated with a decrease in the ionic character of the Bi‒X bond.

Acknowledgements

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Financial support from National University Research Council and Ministry of Education and Research of Romania (Research Project PNII-ID 0659/2011) and from the Fonds der Chemischen Industrie (FCI) is greatly acknowledged. A.T. is grateful

and STIBET).

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Appendix A. Supplementary material

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for financial support from DAAD (fellowship, “Eastern Europe Partnership” program

CCDC 1416630 − 1416632 and 1418493 contain the supplementary crystallographic data for compounds 1 ‒ 3 and 4, respectively. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. The supplementary material contains also figures representing the polymeric associations and the crystal packing in compounds 1 − 4, cartesian coordinates and graphical representations of all the

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optimized structures in xyz format. Supplementary data associated with this article can be found, in

References

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the online version, at ______.

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electrons about a central atom X with L ligands. C. W. Perkins, J. C. Martin, A. J. Arduengo III, W. Lau, A. Alegria, K. Kochi, J. Am. Chem. Soc. 102 (1980) 7753. [28] J. Emsley, Die Elemente, Walter de Gruyter, Berlin, 1994. [29] (a) T. Murafuji, M. Nagasue, Y. Tashiro, Y. Sugihara, N. Azuma, Organometallics

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ACCEPTED MANUSCRIPT Figure captions

Figure 1. Thermal ellipsoids (50% probability) representation and atom numbering scheme for S1,S2-1 isomer (hydrogen atoms are omitted for clarity).

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Figure 2. Thermal ellipsoids (50% probability) representation and atom numbering scheme for S1,S2-2 isomer (hydrogen atoms are omitted for clarity).

Figure 3. Thermal ellipsoids (50% probability) representation and atom numbering scheme

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for S1,S2-3 isomer (hydrogen atoms are omitted for clarity).

Figure 4. Thermal ellipsoids (50% probability) representation and atom numbering

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scheme for S2-4 isomer (hydrogen atoms are omitted for clarity).

Figure 5. Polymeric chain in the crystal of compound 2.

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Figure 6. π Bi1···Cg intermolecular interactions in the crystal of compound 3. Figure 7. Bi···O intermolecular interactions in the crystal of compound 4.

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Scheme 1. Synthesis of compounds 1 – 4.

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Scheme 2. Labelling scheme for the [(C6H4CH2)2S]Bi fragment.

ACCEPTED MANUSCRIPT Table 1. Selected interatomic distances (Å) and angles (o) in compounds [(C6H4CH2)2S]BiBr (1) and [(C6H4CH2)2S]BiI (2) X = Br 1d 2.779(2) 2.261(15) 2.265(17) 2.832(5)

97.8(6) 92.9(4) 88.4(5) 75.0(4) 74.8(5) 157.42(10) 102.1(10) 90.3(6) 92.2(6)

95.8(6) 92.7(4) 89.2(5) 75.3(4) 74.4(5) 158.28(12) 100.7(9) 89.8(6) 94.1(6)

97.1(6) 89.5(5) 93.0(4) 73.5(5) 75.1(4) 157.54(10) 100.4(9) 93.0(6) 92.9(6)

97.0(6) 88.8(5) 92.6(4) 74.1(5) 75.2(4) 157.33(10) 101.5(9) 92.8(6) 90.6(6)

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2a 2.9314(12) 2.260(11) 2.282(12) 2.847(3)

2b 2.9714(11) 2.285(10) 2.267(11) 2.861(4)

91.9(4) 93.3(3) 93.3(4) 74.9(3) 75.5(4) 163.24(8) 101.4(6) 93.8(5) 89.7(5)

89.3(4) 94.3(3) 95.5(3) 75.4(3) 77.1(3) 167.19(7) 101.4(6) 95.5(4) 89.8(4)

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1c 2.779(2) 2.272(16) 2.289(15) 2.836(5)

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1b 2.778(2) 2.245(16) 2.256(16) 2.830(5)

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Ca‒Bi‒Cb Ca‒Bi‒X Cb‒Bi‒X Ca‒Bi‒S Cb‒Bi‒S X‒Bi‒S Cc‒S‒Cd Cc‒S‒Bi Cd‒S‒Bi

1a 2.783(2) 2.255(16) 2.251(16) 2.834(5)

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Bi‒X Bi‒Ca Bi‒Cb Bi−S

X=I

ACCEPTED MANUSCRIPT Table 2. Selected interatomic distances (Å) and angles [(C6H4CH2)2S]BiONO2 (3) and [(C6H4CH2)2S]BiOSO2CF3 (4) 3

compounds

4 2.277(12) 2.272(13) 2.764(3) 2.431(9) 3.041(11)

Bi1‒C1 Bi1‒C14 Bi1−S1 Bi1‒O1 Bi1···O2

2.256(6) 2.261(7) 2.6741(17) 2.571(5) 3.568(5)

88.2(4) 82.3(4) 89.4(4) 77.3(3) 76.6(3) 155.4(2) 102.1(6) 91.6(4) 96.6(4)

C1‒Bi1‒C14 C1‒Bi1‒O1 C14‒Bi1‒O1 C1‒Bi1‒S1 C14‒Bi1‒S1 O1‒Bi1‒S1 C7‒S1‒C8 C7‒S1‒Bi1 C8‒S1‒Bi1

O1‒Bi1···O2 S1‒Bi1···O2 C1‒Bi1···O2 C14‒Bi1···O2

45.7(3) 151.4(2) 127.9(3) 89.7(4)

O1‒Bi1···O2 S1‒Bi1···O2 C1‒Bi1···O2 C14‒Bi1···O2

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96.7(2) 85.5(2) 84.0(2) 79.79(19) 78.82(17) 155.87(12) 103.0(3) 97.4(2) 99.2(3)

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C1‒Bi1‒C14 C1‒Bi1‒O1 C14‒Bi1‒O1 C1‒Bi1‒S1 C14‒Bi1‒S1 O1‒Bi1‒S1 C7‒S1‒C8 C7‒S1‒Bi1 C8‒S1‒Bi1

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in

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Bi1−C1 Bi1−C14 Bi1−S1 Bi1−O1 Bi1···O2

(o)

42.75(1) 161.23(8) 108.15(2) 116.04(2)

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ACCEPTED MANUSCRIPT Highlights

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New hypervalent species [(C6H4CH2)2S]BiX [X = Br (1), I (2), ONO2 (3) and OSO2CF3 (4)] are described.

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The influence of different anionic ligands towards the transannular S→Bi interaction is discussed. DFT calculations were employed in order to evaluate the transannular S→Bi interaction.

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The strength of the S→Bi interaction decreases in the series 4 > 3 > [(C6H4CH2)2S]BiCl > 1

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>2

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Intermolecular H···X (X = Br, I), π Bi···Cg or Bi···O interactions led to polymeric

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associations.

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•