Abstract
The synthesis and single crystal X-ray studies of bis(trimethylsilylmethyl) telluriumdiiodide was studied through an insertion route with quantitative yield. This molecule was characterized with the help of 1H NMR, elemental analysis and single-crystal X-ray studies. The new crystalline molecule provides a supramolecular synthon in crystal lattices of tellurium(IV) diiodide showing 2d synthons associated with the help of C-H - - - I interactions.
Introduction
The first organotellurium compound, diethyltelluride was reported by Wöhler in 1840 [1]. Thereafter a series of organotellurium derivatives has been reported in the literature [2]. In recent years organotellurium chemistry has been paid much attention by several research groups throughout the world because of its potential applications in modern organic synthesis [3], single-source precursors for metal-organic chemical vapour deposition [4], ligand chemistry [5] and biochemistry [6]. Tin-doped tellurium films can be employed for the development of flexible asymmetric pseudocapacitors [7]. A series of hypervalent trifluoromethyl ligands bearing tellurium derivatives were studied by Pietrasiak and Togni in 2017. In this report the authors have treated in situ prepared aryltellurate anion with CF3I [8]. In 2021 Bart and co-workers have reported the synthesis and characterization of half sandwich complexes of selenium and tellurium [9]. In 2002 Tanaka and co-workers have studied the phosphine catalysed insertion reaction of tellurium powder across Sn-Sn and Pb-Pb bonds under mild conditions to isolate the corresponding tellurides R3MTeMR3 (M = Sn and Pb) with quantitative yield [10]. Insertion of tellurium powder across yttrium-carbon bonds was developed by Beletskaya and co-workers with excellent yield [11]. In 2010 Ghosh and co-workers have employed insertion of sulphur, selenium and tellurium atoms into metallaborane cages [12]. Recently A. Sinha and M. Ravikanth have studied the synthesis and characterization of benzofuran-embedded selenaporphyrin and benzofuran-embedded telluraporphyrin macrocycles. In this report the group employed the condensation of benzofuran based tripyrrane with appropriate 2,5-bis(hydroxymethylaryl) selenophene/telluorophene to afford pure benzofuran-embedded selenaporphyrin and telluraporphyrin macrocycles in 3–6% yields [13]. In 2007 Chauhan and co-workers developed a methodology to isolate a bis-organotellurium (IV) derivative through an insertion route at room temperature with isolation of pinacolyltellurium(IV) dihalides [14]. In 2008, the same research group have also employed electrophilic substitution reactions to isolate a series of acylmethyl(aryl)tellurium dichloride (RCOCH2)ArylTeCl2 derivatives with excellent yield at room temperature [15, 16]. In 2010 Misra et al., have reported amidomethylation of tellurium powder as well as in situ generated aryltellurium bromide (ArylTeBr) under mild conditions. This reaction involves oxidative insertion of low valent tellurium into the C–Br bond of N-substituted α-bromoacetamides and provides a direct synthetic route to the stable, crystalline amidomethyltellurium(IV) dibromides [17]. In 2018 we have reported a series of organotellurium (IV)/organomercury(II) derivatives bearing a N,N′,C-chelating aryldiamine ligand [18]. Thereafter in 2019 we also developed a tridentate ligand, N-methyl-N-(naphthalen-2-ylmethyl)-2-(pyridin-2-yl) ethanamine. This ligand was further employed for cyclometallation with Pd(OAc)2 [19]. In 2021 we have studied the single crystal x-ray studies of a cyclic tellurium (IV) molecule [20] and dimesityl ditelluride [21]. Recently Singh and co-workers have developed a series of unsymmetrical selenoethers through nucleophilic substitution reactions followed by facile cleavage of the Se-C bond [22]. In 2022 we reported a series of bis-organotellurium (IV) diiodides through the insertion reaction in good yield [23]. However, the synthesis of bis-(trimethylsilylmethyl) telluriumdiiodide was earlier reported through a different route [24]. In this article, we have reported the synthesis and characterization of bis-(trimethylsilylmethyl) telluriumdiiodide along with single crystal x-ray studies.
Structure determination procedures
X-ray crystallographic studies
Single-crystal x-ray data and structure refinement details for molecule bis-(trimethylsilylmethyl) telluriumdiiodide are given in Table 1. Atomic coordinates and equivalent isotropic displacement parameters for molecule bis-(trimethylsilylmethyl) telluriumdiiodide are shown in Table 2. Anisotropic displacement parameters for bis-(trimethylsilylmethyl) telluriumdiiodide are shown in Table 3. ORTEP observation of its molecular structure is depicted in Fig. 1. Its most important bond length and bond angles relevant to its geometry are shown in captions. A suitable single crystal was selected under an optical microscope and attached on the top of glass fiber for data collection. Intensity data of the molecule was recorded by the use of MoKα (λ= 0.71073 Å) radiation on a Bruker SMART APEX diffractometer with a CCD area detector at 100(2)K. The data was integrated with SAINT software [25]. An experimental absorption modification was applied to the collected reflections with SADABS [26]. The structure was confirmed by direct methods using SHELXTL and was refined on F2 by the full-matrix least-squares procedure using the program SHELXL-2018 [27]. All non-hydrogen atoms were refined with anisotropic dislocation parameters. All H atoms were positioned geometrically and refined with relative isotropic dislocation parameters.
Crystal data and structure refinement for bis-(trimethylsilylmethyl) telluriumdiiodide
Crystal data and structure refinement for bis-(trimethylsilylmethyl) telluriumdiiodide
Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2×103) for bis-(trimethylsilylmethyl) telluriumdiiodide. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor
Anisotropic displacement parameters (Å2×103) for bis-(trimethylsilylmethyl) telluriumdiiodide. The anisotropic displacement factor exponent takes the form: 2p2[h2a*2U11 +...+2 h k a* b* U12]
Synthesis of bis-(trimethylsilylmethyl) telluriumdiiodide.
Recently we have investigated the synthesis and single-crystal X-ray studies of cyclic and acyclic organotellurium(IV) diiodide obtained through an insertion route [23]. Similarly, the desired bis-(trimethylsilylmethyl) telluriumdiiodide molecule was prepared by the treatment of (iodomethyl)trimethylsilane and tellurium powder in a thick-walled glass tube at 130°C for seven days. After seven days the reaction mixture was allowed to cool at room temperature. The reaction mixture was extracted with chloroform solvent in two portions over a period of 10 minutes at room temperature. The extract was evaporated under vacuum to give an orange colour crystalline solid of bis(trimethylsilylmethyl) telluriumdiiodide, which was recrystallized from chloroform afforded needle-shaped crystals. Yield: 0.55 g (20%), mp 58C (Scheme 1). In the 1H NMR spectrum two singlet peak was observed at 0.35 ppm for six methyl group and at 3.07 ppm for two methylene. This molecule was further confirmed with elemental analysis and single-crystal x-ray studies.
Molecular structure of bis-(trimethylsilylmethyl) telluriumdiiodide
The molecular structure of bis-(trimethylsilylmethyl) telluriumdiiodide is shown in Fig. 1. This molecule crystallizes in a triclinic crystal system with space group P-1. Each unit cell contains two molecules. Each molecule is interconnected through reciprocal C-H⋯I intermolecular hydrogen bonding interactions that give rise to centrosymmetric dimeric unit shown in Fig. 2. The geometry around the tellurium atom in the molecules is trigonal bipyramidal in which a lone pair and two carbon atoms are located at the equatorial position and the iodine atoms are situated at the axial site. The observed C–Te–C and I–Te–I bond angle is 99.8(2)° and 175.240(16)° respectively. The C-Te-C bond angle 95.0(7) of (t-BuCOCH2)2TeI2 [14] and 94.6(7) of (m-NO2-C6H4CH2)2TeI2 [23] is significantly smaller than that for molecules (Me3SiCH2)2TeI2: 99.8(2), and (C6H5CH2)2TeI2: 99.71(7) by more than ∼5° [23]. This observation may be attributed to the higher group electronegativity of the m-NO2-C6H4 and t-BuCO fragments in comparison with the phenyl and trimethylsilyl group. This observation is further confirmed by comparing C-Si bond length and C-Si-C bond angles of (Me3SiCH2)2TeI2. The CH2-Si bond length (2.131(5) Å, 2.136(5) Å) is shorter than average bond length of CH3-Si ∼ 1.870 Å in (Me3SiCH2)2TeI2 molecules Table 4. These values are expected to be smaller in comparison to a regular sp3-hybridized atom. These findings are in accordance with the Bent’s rule [28].
In crystal packing diagram appears to contribute significantly to the formation of centrosymmetric dimer through C-H - - - I hydrogen bonding interactions (3.236 Å) in its crystalline state Fig. 2.
The molecular structure of bis-(trimethylsilylmethyl) telluriumdiiodide exhibiting a 50% probability of dislodgment ellipsoids with the atom numbering method. Most important bond distances (Å) and angles (°): Te(1)-C(5): 2.131(5), Te(1)-C(1): 2.136(5), Te(1)-I(2): 2.8895(5), Te(1)-I(1): 2.9504(5), Si(1)-C(4): 1.855(7), Si(1)-C(2): 1.861(6), Si(1)-C(3): 1.861(6), Si(1)-C(1): 1.902(5), Si(2)-C(7): 1.860(7), Si(2)-C(6): 1.865(6), Si(2)-C(8): 1.869(6), Si(2)-C(5): 1.902(6). C(5)-Te(1)-C(1): 99.8(2), C(5)-Te(1)-I(2): 88.13(16), C(1)-Te(1)-I(2): 91.03(14), C(5)-Te(1)-I(1): 87.11(16), C(1)-Te(1)-I(1): 89.74(14), I(2)-Te(1)-I(1): 175.240(16), C(4)-Si(1)-C(2): 111.3(3), C(4)-Si(1)-C(3): 110.8(3), C(2)-Si(1)-C(3): 109.0(4), C(4)-Si(1)-C(1): 106.9(3), C(2)-Si(1)-C(1): 109.4(3), C(3)-Si(1)-C(1): 109.4(3), C(7)-Si(2)-C(6): 108.8(3), C(7)-Si(2)-C(8): 112.0(3), C(6)-Si(2)-C(8): 109.9(3), C(7)-Si(2)-C(5): 106.5(3), C(6)-Si(2)-C(5): 110.8(3), C(8)-Si(2)-C(5): 108.7(3), Si(1)-C(1)-Te(1): 113.0(3), Si(2)-C(5)-Te(1): 113.0(3).
Supramolecular synthon in crystal lattices of tellurium(IV) diiodide showing 2d synthons associated with the help of C-H - - - I interactions.
Most important bond distances (Å) and angles (°) of some reported molecules
Synthesis of compound bis(trimethylsilylmethyl) telluriumdiiodide
We took (iodomethyl)trimethylsilane, (1.50 ml, 10.0 mmol) and tellurium powder (0.64 g, 5 mmol) in a thick-walled glass tube with a stopper. The reaction mixture was allowed to heat at 130°C for seven days. After seven days in the reaction mixture, some orange colour solid of bis(trimethylsilylmethyl) telluriumdiiodide appeared. The reaction mixture was allowed to cool at room temperature. The reaction mixture was extracted with chloroform solvent in two portions over a period of 10 minutes at room temperature. The extract was evaporated under vacuum to give an orange colour crystalline solids of bis(trimethylsilylmethyl) telluriumdiiodide, which was recrystallized from chloroform afforded needle-shaped crystal. Yield: 0.55 g (20%), mp 58C. Anal. Calcd. For C8H22SiTeI2: C, 17.29; H, 3.99. Found: C, 18.10, H 4.00. 1H NMR (400 MHz, CDCl3): &delta 0.35 (s, 9H- Me3Si), 3.07 (s, 2H- CH2).
Conclusion
For the first time we are able to report the synthesis and characterization of bis-(trimethylsilylmethyl) telluriumdiiodide through the insertion route. In this work, we are able to generate two C-Te bonds in a single molecule through one pot synthesis. The geometry around tellurium atoms in the molecule is explained with the help of Bent’s rule. The new crystalline molecule provides supramolecular synthon in crystal lattices of tellurium(IV) diiodide showing 2d synthons associated with the help of C-H - - - I interactions.
Footnotes
Acknowledgment
PS and JKB is heartily thankful to the Science and Engineering Research Board, New Delhi, India for Teachers Associateship for Research Excellence Grant (Project No. TAR/2021/000075). We are also thankful to Central Drug Research Institute Lucknow for recording analytical data.
