Heavy Neutral and Anionic Pnictogen Thiocyanates - Inorganic

Article pubs.acs.org/IC

Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

Heavy Neutral and Anionic Pnictogen Thiocyanates Sören Arlt,† Jörg Harloff,† Axel Schulz,*,†,‡ Alrik Stoffers,† and Alexander Villinger† †

Institut für Chemie and ‡Leibniz-Institut für Katalyse, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany

Inorg. Chem. Downloaded from pubs.acs.org by UNIV OF LOUISIANA AT LAFAYETTE on 04/01/19. For personal use only.

S Supporting Information *

ABSTRACT: When [PPN]SCN (1; PPN = [Ph3P−N−PPh3]) is treated with Me3Si−SCN in methanol, [PPN][H(NCS)2] (2), a hydrogen diisothiocyanate salt bearing the [H(NCS)2]− anion, was generated, isolated, and fully characterized. Pure heavy E(NCS)3 [E = Sb (3), Bi (4)] species were obtained from the reaction of EF3 and an excess of Me3Si− SCN, while the tetrahydrofuran (THF) solvates E(NCS)3·THF were isolated when the product was recrystallized from THF. When 2 equiv of 1 was combined with Me3Si−SCN and SbF3, [PPN]2[Sb(NCS)5] (5) could be isolated. When 1 was added to BiF3, [PPN]2[Bi(NCS)3(SCN)2·THF] (6·THF), containing three SCN− ions coordinating via the N atom and two coordinating via the S atom, was isolated after recrystallization from THF. The structures of 1, 2, 3·THF, 4·THF, 5, and 6·THF were determined. 3·THF displayed a typical [3 + 3] coordination mode with a trigonal-pyramidal environment in the first coordination sphere of the Sb3+ ion, and the dianion of 5, [Sb(NCS)5]2−, featured a classical square-pyramidal molecular geometry around the Sb3+ ion with one additional Menshutkin-type interaction to one aryl ring of the [PPN]+ cation. 4·THF exhibited a distorted pentagonalbipyramidal structure within a two-dimensional network, while in 6·THF, an octahedrally surrounded Bi3+ ion was observed.

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INTRODUCTION Thiocyanic acid, HSCN (first known as Schwefelblausäure, which is German for sulfur blue acid), was already observed in 1790 by Winterl, 1798 by Buchholz,1 and 1804 by Rink and prepared in 1808 by Porret.2 Its composition was determined by Berzelius in 1820, and he also introduced the old name rhodanic acid (from Greek for red) because iron(III) thiocyanate is a deep-red complex. Thiocyanate salts can be prepared from cyanides and sulfur in the melt.2 In addition to HSCN, an isomer is also known, namely, isothiocyanic acid (HNCS, also known as thiocarbimide). The thiocyanate ion, like the azide, cyanide, or cyanate, is referred to as a linear pseudohalide that easily forms salts with alkali metals such as potassium thiocyanate (KSCN, also known as potassium rhodanide).3−7 As early as 1873, Lössner converted phosphorus trichloride with KSCN into P(SCN)3 in an alcoholic solution.8 Shortly thereafter, the reactions of PCl3, AsCl3, and SbCl3 with metal thiocyanates (MSCN, where M = alkali metal) were studied by different groups.9 Formation of the thiocyanates P(SCN)3, As(SCN)3, and Sb(SCN)3 was assumed because, upon contact of these E(SCN)3 (E = P, As, and Sb) species with water, HSCN was observed. In 1902, Dixon studied the reaction of PCl3 with KSCN in detail in order to investigate the behavior of P(SCN)3 toward alcohol.10 It was Söderbäck who advanced thiocyanate chemistry and dealt, in particular, with the synthesis of free HSCN and its salts. In the course of these investigations, he examined the effect of HSCN−ether solutions on pure arsenic and antimony, whereby he could isolate a yellow hygroscopic oily solid.11 To date, various synthetic routes to P(SCN)3 have been published, most of them starting from PCl3 and metal thiocyanates such as AgSCN, Hg(SCN)2, or NH4SCN (Scheme 1).12,13 © XXXX American Chemical Society

Scheme 1. Known Synthese of P(SCN)3

A structural characterization of the phosphorus trithiocyanate liquid at room temperature was not possible because of its instability.13 There are only a few references with regard to the heavier E(SCN)3 (E = As, Sb) molecules, which were obtained analogous to P(SCN)3 in the reaction of the element trichlorides with 3 equiv of AgSCN.14,15 The arsenic trithiocyanate could be isolated at lower temperatures as a white solid but decomposed readily at room temperature.14 Antimony trithiocyanate coordination compounds with further neutral ligands such as naphthalene, pyridine, or urea were isolated and characterized by elemental analysis.16,17 Structural characterization is unknown for the pure arsenic and antimony trithiocyanate compounds. The situation is different with bismuth trithiocyanate, which was already discussed by Bender as early as 1887.18 The first structural characterization of bismuth trithiocyanate stabilized by 5-amino-1,2,4-dithiazole3-thione was achieved by Bensch et al. in 1989.19 In 2010, the group of Ruck succeeded in synthesizing a water-bridged complex of bismuth trithiocyanate.20 For this purpose, the carbonate (BiO)2CO3 was reacted with freshly prepared HSCN. To the best of our knowledge, a solvent-free structure is not yet known. Also, relatively little is known about ionic Received: February 8, 2019

A

DOI: 10.1021/acs.inorgchem.9b00378 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry pnictogen thiocyanate compounds such as [E(SCN)n]m− (EIII = pnictogen, n = 4−6, m = 1−3; EV, n = 6, m = 1). In 1982, Dillon and Platt described the synthesis of hexathiocyanatophosphate ([P(NCS)6]−) and observed the decomposition of that compound at room temperature.21 Partially substituted compounds of the type [PX6−n(SCN)n]− (X = F, Cl; n = 1−5) were also isolated by Dillon and Platt, however, without structure determination.21,22 Arsenic variants of anions of the type [AsX6−n(SCN)n]− or [AsX4−n(NCS)n]− (X = halogen) are not known; however, salts bearing [As(CH3SO3)(NCS)3]− with a methyl sulfate instead of a halide were reported in 1987.23 The heavier homologues [E(CH3SO3)(NCS)3]− (E = Sb, Bi) were described by Kapoor et al.23 The anion [SbPh(NCS)3]− was structurally characterized in 1995 by Sowerby et al.24 All hitherto known antimony thiocyanate species25−28 are of the type [SbR(NCS)3]− or [Sb(OR)(NCS)3]− (R = organic substituent). To the best of our knowledge, a pure antimony trithiocyanate could not yet be structurally characterized, although Bertazzi and Alonzo described the synthesis of [NH4][Sb(NCS)4] (Scheme 2) in 1989. On the basis of mass spectrometry data, they postulated a possible structural arrangement of the thiocyanates around the antimony.17

Figure 1. Ball-and-stick representation of the molecular structure of 2 in the crystal. Selected bond lengths (Å) and angles (deg): N1−H1 1.33(5), N2−H1 1.21(5), N1−C1 1.155(6), C1−S1 1.615(5), N2− C2 1.155(6), C2−S2 1.606(5), N1···N2 2.533(7); N1−H1−N2 173(5), H1−N1−C1 151(2), H1−N2−C2 169(2), N1−C1−S1 178.5(4), N2−C2−S2 179.0(5), C1−N1−N2 165.5(2). Shown is only one of the two independent molecules.

of [PPh4][H(NCS)2], which was obtained accidently as a byproduct in the reaction of uranium tetrachloride with sodium thiocyanate and tetraphenylphosphonium chloride.51 Moreover, a polymorph of 1 has been reported previously.52 With pure thiocyanate salts in hand, we attempted the synthesis of pure, solvate-free E(SCN)3 (E = Sb, Bi). In the reaction of antimony trifluoride with trimethylsilyl isothiocyanate in THF, the previously structurally unknown Sb(SCN)3· THF (3·THF) and Bi(SCN)3·THF (4·THF) could be synthesized (Scheme 4, eq 3). When both compounds (3· THF and 4·THF) are subjected to prolonged pumping or when the reaction was carried out in an excess of Me3Si−SCN (without THF), the solvent-free E(SCN)3 can be obtained. Despite storage under argon as a protective gas, a discoloration to yellow and later orange in the crystallization process was observed after a few days, which indicated slow decomposition even at ambient conditions. Salts containing the [E(SCN)5]2− ion (E = Sb, Bi) were prepared in the reaction of the trifluoride EF3 with 2 equiv of 1 and 3 equiv of Me3Si−SCN in MeCN. Crystals of [PPN]2[E(SCN)5] salts were obtained after recrystallization from THF. Interestingly, [PPN]2[Sb(SCN)5] (5) crystallized as a pure salt, whereas [PPN]2[Bi(SCN)5·THF] (6·THF) crystallized as THF monosolvate. Spectroscopic Characterization. The heavy pnictogen trithiocyanates (3 and 4) must be stored under inert gas at a lower temperature because they decompose slowly at room temperature and are very sensitive to oxygen as well as moisture (Table 1). Above 100 °C, a fairly rapid decomposition occurs, beginning with coloration to a deep-orange color. A similar thermal behavior was found for the pentathiocyanate complexes. IR and Raman spectroscopic studies revealed the existence of SC−N stretching modes in the expected range between 1930 and 2122 cm−1. A strong splitting of the SC−N stretching vibration was observed, especially for the pentathiocyanate complexes because the SCN ions can be differently linked to the pnictogen ions (see below). IG 13C NMR spectroscopy studies (IG = inverse gated) were performed to determine the number of SCN groups coordinated to the formal Sb3+ ion of [PPN]2[Sb(NCS)5] (5) in solution. For compound 5, five magnetically equivalent SCN ions could be determined by calibration and a

Scheme 2. Synthesis of [Me4N][Sb(NCS)4]

In 2009, Renz et al. mentioned the synthesis of iron/ antimony rhodanide clusters, however, without any structural data.29,30 As early as 1976 and 1994, Galdecki et al. and Crispini et al. reported on the structure of salts containing the anions [Bi(NCS)4]− and [Bi(NCS)6]3−, respectively.31,32 Following our long-standing interest in pseudohalide chemistry,33−48 we report here in detail on the synthesis and structure of antimony and bismuth thiocyanates.

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RESULTS AND DISCUSSION Synthesis. We started this project with a detailed study of the solubilities of thiocyanates in various solvents, e.g., water, methanol (MeOH), acetonitrile (MeCN), dichloromethane (CH2Cl2), or even ionic liquids such as 1-butyl-3-methylimidazolium triflate (BMimOTf). We were particularly interested in the synthesis of [WCC]SCN salts (WCC = weakly coordinating cation) such as bis(triphenylphosphine)iminium thiocyanate {[PPN]SCN (1), where PPN+ = [Ph3P− N−PPh3]+} to reduce the cation−anion interaction.44,49,50 As expected, KSCN dissolves well in protic polar solvents but poorly in organic solvents, while 1 dissolves well in MeOH, CH2Cl2, and MeCN but poorly in water. Surprisingly, in the reaction of [PPN]Cl with an excess of KSCN, we obtained [PPN][H(NCS)2] (2; Figure 1) rather than the expected 1, which prompted us to find a direct synthesis. First, in a next step, the desired 1 could be obtained from water by a modified literature synthesis, exploiting the poor solubility of 1 in water (Scheme 3, eq 1).35 Second, for compound 2, a direct synthetic route could be established starting from 1 and Me3Si−SCN in MeOH with isolated yields >98% (Scheme 3, eq 2). These two routes enabled us to prepare, isolate, and structurally characterize pure 1, 1·THF, and 2. It should be mentioned that in 2016 Nuzzo et al. published structural data B


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Inorganic Chemistry Scheme 3. Syntheses of 1 and 2

compared to ∑rcov= 2.11 Å)53 and three rather long Sb···S (average 3.098 Å, compared to ∑rvan der Waals = 3.86 Å)54 distances are found. Actually, there are two further, rather long Sb···S distances (average 3.818 Å) that are within the sum of the van der Waals radii (Table 2), which means a [3 + 3 + 2] coordination55 mode could also be discussed. A view along the c axis in the unit cell features the 4-fold screw axis (Figure 3, right). Similar to the structure of 3, the THF solvate 3·THF also exhibits three short Sb−N bond lengths (average 2.107 Å; Table 2), leading to a formal trigonal-pyramidal arrangement of the strongly bound three SCN− ions (Figure 4, left). However, the THF molecule, bound via the O atom, features a bond length of 2.421(5) Å (cf. ∑rcov = 2.03 Å;53 ∑rvan der Waals = 3.59 Å),54 which lies between a covalent and van der Waals type Sb−O bond. Hence, a bisphenoidal (pseudotrigonalbipyramidal) environment around the Sb atom can also be assumed in accordance with the rather large O1−Sb1−N1 angle of 156.5(1)°. In addition, two van der Waals interactions can be discussed between the Sb3+ and two SCN ions of two adjacent Sb(SCN)3 moieties [avarage d(Sb···S) = 3.209 Å]. So, either a [3 + 1 + 2] or a [4 + 2] coordination mode can be discussed.55 Again there are also two very weak Sb···S van der Waals interactions [d(Sb···S) = 3.885 Å], as found in 3 (vide supra). The view along the b axis in the unit cell displays 1,1 coordination via the S atom of two different SCN− ions, leading to 4-membered Sb2S2 rings, as well as 1,3 coordination of two different SCN− ions, resulting in 8-membered Sb2(SCN)2 rings (Figure 4, right). 5 crystallizes in the monoclinic space group P21/c with four formula units in the unit cell. The anion adopts a distorted square-pyramidal geometry with a SbN5 core (Figure 5, left). The Sb−N bond lengths in the square base are between 2.206(3) and 2.322(4) Å. In contrast, the bond to the apical thiocyanate group is significantly shorter with 2.045(3) Å, which is even slightly below the sum of the covalent radii [∑rcov(Sb−N) = 2.11 Å].53 The angles between the basal and apical thiocyanates are all less than 90°. The thiocyanate ligands coordinate all via the N atom of the thiocyanate to the Sb3+ ion and show an angled arrangement [∠(Sb−N−C) between 140.1(3) and 169.1(3)°]. Compared to the Sb−N bond lengths in 3, the averaged Sb−N distances in the first coordination sphere are slightly elongated (2.222 vs 2.098 Å) due to the increased coordination number. At a first glance, there are no significant interionic cation− anion or anion−anion contacts (shortest distance S2···S4′ 4.248(2) Å; Figure 5, right). However, a closer look at the Sb···

Scheme 4. Synthesis of E(SCN)3 and [PPN]2[E(SCN)5] (E = Sb, Bi)

comparison with the signal of the cation [PPN]+ (Figure 2). The rather broad 13C NMR shift at 138 ppm was assigned to the C atom of the five thiocyanate groups, which is the most downfield-shifted signal in the spectrum of 5. It was impossible to resolve the intramolecular dynamic exchange within the [Sb(SCN)5]2− ion. Structure Elucidation. Besides the structures of the starting materials 1 (Figure S1 and Table S4), 1·THF (Figure S2), and 2 (Figure 1), the structures of Sb(NCS)3 (3; Figure 3), 3·THF (Figure 4), 5 (Figures 5 and 6), 4·THF (Figure 7), and 6·THF (Figure 8) were determined. Selected average bond lengths are summarized in Table 2. While Figures 1 and 3−8 show ball-and-stick represantations of the pnictogen thiocyanate compounds for clarity, ORTEP representations can be found in Figures S1−S8. Crystallographic details are summarized in Tables S1−S3. 2 crystallizes in the triclinic space group P1̅ with two independent molecules and four formula units per unit cell. Because most of the structural data of the anion in 2 are similar to those of the accidently found [PPh4][H(NCS)2] salt (monoclinic space group P21/c), we will abstain from a extensive discussion and refer to the work of Nuzzo et al.51 However, a closer look at the C−N−N angles revealed significantly different values [Figure 1; cf. ∠(C1−N1−N2) = 165.5(2) vs 171.6(2)°], which can be attributed to a rather flat potential energy surface regarding the C−N−N angle. Hence, a change from the [PPh4]+ ion (Nuzzo et al.) to the [PPN]+ cation, as in this work, has a considerable influence on the structural parameters that are associated with a flat potential energy surface (such as the C−N−N angle or even localization of the proton). 3 crystallizes in the tetragonal space group I41cd with 16 formula units in the unit cell. In contrast, 3·THF crystallizes in the monoclinic space group P21/n with four formula units. The neutral, solvent-free compound 3 exhibits a distorted trigonalpyramidal molecular structure (Figure 3, left), in which the coordination sphere of the central antimony is extended by coordination via the sulfur to three adjacent thiocyanate groups, finally leading to [3 + 3] coordination.55 In accordance with this consideration, three short Sb−N (average 2.098 Å,

Table 1. Spectroscopic Details (Melting Points in °C and CN Stretching Modes in cm−1) of Thiocyanate Species 1−6 1 MP νCN,IR

193 2052 (m)

νCN,Raman

2052(5)

2 129 2048 (s,br) 2051(1)

3·THF

4·THF

130a 1932 (vs,br)

121a 2083 (s,br)

2122(2), 2083(4), 2060(3), 2029(2), 2004(2)

2105(10), 2072(2)

5 141 2073 (m), 2037 (m), 2013 (s), 1988 (s), 1975 (s) 2076(1), 2068(1), 2042(2), 2026(5), 1993(1)

6·THF 114 2114 (w), 2102 (m), 2033 (s), 1975 (m), 1944 (s) 2116(5), 2054(1), 1980(1), 1950(1),

a

Decomposition. C


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Inorganic Chemistry

Figure 2. IG 13C NMR spectrum of 5 in CD3CN. The inset shows the enlarged resonances in the region 127−139 ppm that correspond to the structural formula on the right.

Caryl,PNP distances revealed a weak cation−anion interaction, as manifested by a shortened Sb···Caryl,PNP distance [d(Sb1···C58) = 3.677(4) Å, compared to ∑rvan der Waals = 3.76 Å],54 which can be understood as a weak Menshutkin-type interaction (Figure 6).56−58 Yellow crystals of 4·THF crystallize in the monoclinic space group P21/c. As illustrated in Figure 7 (top), the coordination around the Bi3+ ion is best described by a strongly distorted pentagonal bipyramid. Contrary to the analogous antimony structure 3·THF (Figure 4), there is no clear molecular Bi(SCN)3 entity with a [3 + 3] coordination mode.55 All Bi−N [2.412−2.617 Å, compared to ∑rcov(Bi−N) = 2.22 Å and ∑rvdW(Bi···N) = 3.62 Å] and Bi−S [2.751−2.847 Å, compared

Table 2. Selected Average Bond Lengths (Å) of 2−6 along with the Sum of the Covalent and van der Waals Radii E−N E−S E−O ∑rcov53 ∑rvdW54

2

3

2.534a 3.557b

2.098 3.098

Sb−N

Sb−S

2.11 3.61

2.43 3.86

3·THF

4·THF

5

6·THF

2.107 3.209 2.421 Sb−O

2.505 2.802 2.555 Bi−N

2.222 8.107c Bi−S

2.364 2.788 2.648 Bi−O

2.22 3.62

2.54 3.87

2.14 3.59

2.03 3.58

a

E = N, N1, ..., N2 distance. bE = C, shortest S···Caryl,cation distance. Shortest Sb···S distance between adjacent anions.

c

Figure 3. 2.103(3), 1.165(4), 83.87(9), 178.1(3).

Left: Ball-and-stick representation of the molecular structure of 3 in the crystal. Selected bond lengths (Å) and angles (deg): Sb1−N1 Sb1−N2 2.099(2), Sb1−N3 2.093(2), Sb1···S3′ 3.1178(6), Sb1···S3′′ 3.0479(8), Sb1···S3‴ 3.1293(7), N1−C1 1.182(4), N2−C2 N3−C3 1.175(4), C1−S1 1.600(3), C2−S2 1.613(3), C3−S3 1.607(3); N1−Sb1−N2 87.9(1), N1−Sb1−N3 85.6(1), N2−Sb1−N3 Sb1−N1−C1 138.9(3), Sb1−N2−C2 175.6(2), Sb1−N3−C3 141.6(2), N1−C1−S1 177.7(3), N2−C2−S2 179.0(3), N3−C3−S3 Symmetry code: ′, 1 − x, y, −0.5 + z, ′′, 1 − y, 0.5 + x, 0.25 + z; ‴, 1 − x, y, 0.5 + z. Right: Unit cell, viewed along the c axis. D


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Inorganic Chemistry

Figure 4. Left: Ball-and-stick representation of the molecular structure of 3·THF in the crystal. Selected bond lengths (Å) and angles (deg): Sb1− N1 2.151(2), Sb1−N2 2.070(2), Sb1−N3 2.101(3), N1−C1 1.162(4), N2−C2 1.182(3), N3−C3 1.178(4), C1−S1 1.610(3), C2−S2 1.586(3), C3−S3 1.600(3), Sb1···S1′ 3.140(2), Sb1···S3′ 3.2774(8), Sb1---O1 2.421(5); N1−Sb1−N2 86.36(9), N1−Sb1−N3 85.9(1), N2−Sb1−N3 86.5(1), Sb1−N1−C1 145.3(3), Sb1−N2−C2 138.2(2), Sb1−N3−C3 146.2(2), N1−C1−S1 178.3(3), N2−C2−S2 176.7(2), N3−C3−S3 176.7(3), O1−Sb1−N1 156.4(2), O1−Sb1−N2 76.6(2), O1−Sb1−N3 77.0(2). Right: Unit cell, viewed along the b axis.

Figure 5. Left: Ball-and-stick representation of the molecular structure of 5 in the crystal. Selected bond lengths (Å) and angles (deg): Sb1−N1 2.322(4), Sb1−N2 2.254(4), Sb1−N3 2.045(3), Sb1−N4 2.206(3), Sb1−N5 2.284(3), N1−C1 1.154(5), C1−S1 1.620(4), N2−C2 1.158(5), C2−S2 1.609(4), N3−C3 1.171(4), C3−S3 1.591(4), N4−C4 1.163(5), C4−S4 1.606(4), N5−C5 1.173(5), C5−S5 1.617(4); N1−Sb1−N2 90.7(2), N1−Sb1−N3 79.5(2), N1−Sb1−N4 162.4(2), N1−Sb1−N5 90.3(2), N2−Sb1−N3 81.3(2), N2−Sb1−N4 88.4(2), N2−Sb1−N5 163.2(2), N3−Sb1−N4 83.0(2), N3−Sb1−N5 82.3(2), N4−Sb1−N5 85.5(2), C1−N1−Sb1 149.9(3), C2−N2−Sb1 169.1(3), C3−N3−Sb1 161.2(3), C4−N4−Sb1 140.1(3), C5−N5−Sb1 149.8(3), N1−C1−S1 178.9(4), N2−C2−S2 177.5(4), N3−C3−S3 178.5(4), N4−C4−S4 177.4(4), N5−C5−S5 178.2(3). Right: Unit cell, viewed along the c axis.

sum of the covalent radii but significantly shorter than the sum of the van der Waals radii (Table 2).53,54 The same holds true for the Bi−O bond lengths with the THF molecule [2.555 Å, compared to ∑rcov(Bi−O) = 2.14 Å and ∑rvdW(Bi···O) = 3.59 Å].53,54 Taking these bond lengths and bond angles into account, the pentagon is composed of N1, N2, N3, S3‴, and O1, while the two apical positions are occupied by S1′ and S2′′, in accordance with the rather large S1′−Bi1−S2′′ angle of 164.43(4)°. As depicted in Figure 7, the most prominent structural feature within the cell is the existence of three (almost trigonally arranged) 8-membered rings composed of Bi(SCN)2 inversion dimers (always with a 1,3 coordination of the SCN− ion), leading to the formation of a two-dimensional network. The coordination around the Bi3+ cations in 4·THF resembles that described by Ruck et al. for Bi(SCN)3·1/2H2O (triclinic space group P1̅),20 for which a coordination mode of [7 + 1] for one Bi3+ (four S, three N, and one O donor atoms)55 and a heptacoordination for a second independent Bi3+ ion (three N, three S, and one O donor atoms) are

Figure 6. Ball-and-stick representation of the Menshutkin-type interaction in 5 in the crystal: Sb1···C58 3.677(4) Å.

to ∑rcov(Bi−S) = 2.54 Å, compared to ∑rvdW(Bi···S) = 3.87 Å] bond lengths are only slightly elongated compared to the E


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Inorganic Chemistry

discussed. However, in contrast to our structure, Bi(SCN)3·1/2H2O exhibits 1,1 SCN− coordination along with a μ2-bridging water molecule, resulting in the formation of Bi2OS 4-membered rings.20 Yellow crystals of 6·THF crystallize in the monoclinic space group P21 with two formula units per cell. Interestingly, there are no significant interactions between the cations and anions or between the complex anions [shortest interanionic distances d(Bi···S) = 6.381(2), compared to ∑rvdW(Bi···S) = 3.87 Å; Figure 8].54 Even more puzzling in comparison with the analogous antimony compound is the fact that three of the five thiocyanate ions coordinate to the Bi3+ ion via the N atom, while two SCN− ions are linked via the S atom. In addition, the THF molecule also coordinates via the O atom to the Bi3+ ion. All in all, this results in a slightly distorted octahedral coordination environment for the Bi3+ center. Because there is no significant interaction between the anions [shortest distance d(Bi···Bi) = 9.8913(5) Å], it follows that each octahedral, Bi3+containing anion, [Bi(NCS)3(SCN)2(THF)]2−, is exclusively surrounded by [PPN]+ cations. Interestingly, the distortion of the octahedral BiS2N3O core is fairly small, as manifested by the S4−Bi1−S5 (178.1°), N−Bi−N (between 84.3 and 85.2°), and N−Bi−S (88.3−92.1°) angles. In comparison with the bond lengths in 4·THF, the averaged Bi−N and Bi−S bond lengths in 6·THF are significantly shorter [d(Bi−N) = 2.364 vs 2.505 Å and d(Bi−S) = 2.787 vs 2.802 Å; Table 2]. Only the Bi−O bond length is slightly longer with 2.648(5) Å, compared to 2.555(7) Å (4·THF). Interestingly, in the already reported octahedral [Bi(SCN)6]3− ion, a slightly distorted BiS6 octahedron is found, but no coordination via the N atom of the SCN− ion is found in 6·THF.32 SCN/NCS isomerism has been found before, for example, for many transition-metal SCN complexes.59

Figure 7. Top: Ball-and-stick representation of the coordination environment around the Bi1 center in 4·THF in the crystal. Selected bond lengths (Å) and angles (deg): Bi1−N1 2.485(5), Bi1−N2 2.412(5), Bi1−N3 2.617(5), N1−C1 1.151(7), N2−C2 1.158(7), N3−C3 1.153(7), C1−S1 1.658(6), C2−S2 1.643(5), C3−S3 1.153(7), Bi1−S1′ 2.808(2), Bi1−S2′′ 2.847(2), Bi1−S3‴ 2.751(2), Bi1−O1 2.555(7); N1−Bi1−N2 147.4(2), N1−Bi1−N3 73.2(2), N2−Bi1−N3 139.3(2), Bi1−N1−C1 161.8(4), Bi1−N2−C2 159.0(4), Bi1−N3−C3 161.3(4), N1−C1−S1 178.0(5), N2−C2− S2 177.8(5), N3−C3−S3 179.0(5), O1−Bi1−N1 127.7(3), O1− Bi1−N2 73.9(5), O1−Bi1−N3 74.4(6). Bottom: view along the a axis of a 2 × 2 × 2 cell representation. Symmetry codes: ′, 1 − x, −0.5 + y, 1.5 − z; ′′, 1 − x, 1 − y, 1 − z; ‴, 1 − x, 0.5 + y, 1.5 − z. THF molecules are disordered.

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CONCLUSION

In summary, an easy route to synthesizing solvate-free heavy pnictogen trithiocyanates E(NCS)3 (E = Sb, Bi) is the reaction of EF3 with an excess of Me3Si−SCN, wherein the Me3Si−

Figure 8. Left: Ball-and-stick representation of the coordination environment around the Bi1 center in 6·THF in the crystal. Selected bond lengths (Å) and angles (deg): Bi1−N1 2.499(6), Bi1−N2 2.282(6), Bi1−N3 2.361(6), Bi1−S4 2.739(2), Bi1−S5 2.836(2), N1−C1 1.157(9), N2−C2 1.036(9), N3−C3 1.160(9), N4−C4 1.16(2), N5−C5 1.17(1), C1−S1 1.617(8), C2−S2 1.647(9), C3−S3 1.618(7), C4−S4 1.64(2), C5−S5 1.648(8), Bi1---O1 2.648(5); N1−Bi1−N2 84.3(2), N1−B1−N3 169.3(2), N1−Bi1−S4 89.2(2), N1−Bi1−S5 92.1(2), N1−Bi1−O1 111.6(2), N2−Bi1−N3 85.1(2), N2−Bi1−S4 90.4(2), N2−Bi1−S5 88.3(2), N2−Bi1−O1 160.5(2), N3−Bi1−S4 89.3(2), N3−Bi1−S5 89.2(2), N3−Bi1− O1 78.5(2), S4−Bi1−S5 178.1(1), S4−Bi1−O1 79.1(2), S5−Bi1−O1 101.8(2), Bi1−N1−C1 173.8(5), Bi1−N2−C2 123.9(5), Bi1−N3−C3 159.5(5), Bi1−S4−C4 102.4(3), Bi1−S5−C5 94.0(2), N1−C1−S1 179.7(8), N2−C2−S2 174.2(7), N3−C3−S3 177.8(6), N4−C4−S4 176.1(8), N5−C5−S5 179.3(7). Right: unit cell, viewed along the a axis. F


Article

Inorganic Chemistry

(m), 997 (s), 972 (m), 908 (s), 847 (m), 797 (w), 744 (m), 723 (s), 687 (vs), 663 (s), 619 (s), 608 (s), 571 (s), 542 (vs). Raman (633 nm, D00, ×10, 20s, 20 acc., cm−1): 3056 (4), 2051 (1), 1588 (4), 1573 (1), 1182 (1), 1160 (1), 1109 (3), 1025 (4), 1000 (10), 662 (3), 613 (2), 357 (1), 282 (0), 264 (2), 256 (1), 246 (1), 232 (2), 227 (2). Sb(NCS)3/Sb(NCS)3·THF (3/3·THF). SbF3 (0.5 g, 2.8 mmol) was dissolved in THF (10 mL). Subsequently, trimethylsilyl isothiocyanate (3.5 mL, 3.305 g, 25.2 mmol) was added and stirred for 16 h at ambient temperature. After removal of the solvent in vacuo, the product 3·THF was isolated with a yield of 0.870 g (84.4%). 3·THF (366.9 g/mol). Mp: 130 °C (dec). Elem anal. Calcd (found): C, 22.41 (22.84); H, 2.15 (2.19); N, 11.34 (11.42); S, 26.66 (26.13). IR (ATR, 25 °C, 128 scans, cm−1): 2980 (m), 2955 (m), 2930 (m), 2883 (m), 2490 (m), 2328 (w), 1932 (vs, br), 1603 (s), 1493 (s), 1479 (s), 1454 (s), 1446 (s), 1379 (s), 1362 (s), 1294 (s), 1254 (s), 1173 (s), 1136 (s), 1032 (s), 1013 (s), 953 (s), 916 (s), 885 (s), 827 (s), 766 (s), 663 (s), 582 (s), 528 (s). Raman (633 nm, D00, ×10, 30s, 30 acc., cm−1): 2982 (0), 2937 (0), 2892 (0), 2122 (2), 2083 (4), 2060 (3), 2029 (2), 2004 (2), 1974 (3), 1608 (1), 1494 (1), 1381 (3), 1337 (1), 1310 (1), 1017 (1), 940 (1), 922 (0), 889 (0), 851 (0), 823 (0), 736 (1), 662 (3), 597 (1), 544 (4), 506 (10), 491 (2), 470 (3), 447 (0), 410 (3), 376 (1), 337 (8), 317 (2), 274 (0), 254 (3), 214 (5). MS (EI): m/z (%) 44 (15.3) ([CS]+), 76 (100), 77 (3.7), 78 (12.4) ([CS2]+), 121 (11.3), 123 (8.7) ([Sb]+), 179 (48.6), 180 (1.2), 181 (34.3) ([Sb(NCS)]+), 237 (50.0), 238 (2.0) 239 (41.0) ([Sb(NCS)2]+), 295 (44.9), 296 (2.6), 297 (42.3), 299 (4.1) ([Sb(NCS)3]+). Unsolvated 3 was obtained after prolonged pumping or from the reaction of SbF3 in an excess of trimethylsilyl isothiocyanate. Elem anal. Calcd (found): C, 12.17 (12.26); N, 14.20 (13.10). Bi(NCS)3/Bi(NCS)3·THF (4/4·THF). BiF3 (0.5 g, 1.9 mmol) was suspended in THF (10 mL). Subsequently, trimethylsilyl isothiocyanate (2.4 mL, 2.2 g, 16.9 mmol) was added and stirred for 16 h at ambient temperature. The solution was filtered and the solvent removed in vacuo. The product had a yield of 0.220 g (25%). Mp: 121 °C (dec). Elem anal. Calcd (found) for 4·THF: C, 18.46 (17.27); H, 1.77 (1.38); N, 9.23 (9.71); S, 21.23 (22.57). 1H NMR (250 MHz, THF-d8): δ 3.70−3.47 (m, OCH2), 1.85−1.62 (m, CH2), 0.30−0.23 (m), 0.20−0.10 (m), 0.05 to −0.02 (m). 13C NMR (62 MHz, THFd8): δ 68.4 (s), 26.6 (s), 2.2 (s), 0.1 (t, J = 7.6 Hz). IR (ATR, 25 °C, 32 scans, cm−1): 2945 (w), 2883 (w), 2083 (s, br), 1454 (s), 1365 (s), 1340 (s), 1022 (vs), 916 (s), 858 (vs), 771 (s), 731 (s), 662 (s). Raman (633 nm, D06, ×10, 10s, 20 acc., cm−1): 2986 (0), 2886 (0), 2105 (10), 2072 (2), 915 (0), 885 (0), 773 (0), 750 (1), 731 (1), 463 (1), 447 (1), 443 (1), 223 (6), 194 (3), 157 (3). Pure 4 was obtained after prolonged pumping in vacuo: C, 9.40 (9.37); H, 0.0 (0.17); N, 10.96 (10.70); S, 25.10 (24.60). [PPN]2[Sb(NCS)5] (5). 1 (4.4 g, 7.37 mmol) and SbF3 (0.4394 g, 2.46 mmol) were dissolved in MeCN (20 mL). Subsequently, trimethylsilyl isothiocyanate (4.0 mL, 3.724 g, 22.4 mmol) was added and stirred at room temperature for 16 h. After removal of the solvent, the crude product was recrystallized from a THF solution (25 mL). The product was isolated with a yield of 1.254 g (11.4%). Mp: 141 °C. Elem anal. Calcd (found): C, 62.10 (61.53); H, 4.06 (4.00); N, 6.58 (6.28); S, 10.77 (10.56). 1H NMR (300 MHz, CD3CN): δ 7.72−7.42 (m, 60H, HPh), 3.99 (s, br), 3.69−3.60 (m, OCH2), 1.83− 1.77 (m, CH2). 13C NMR (75 MHz, CD3CN): δ 140.1 (SCN), 134.6 (Cpara), 133.4−133.1 (m, Cmeta), 130.6−130.1 (m, Cortho), 128.2 (dd, 1 13 31 J[ C, P] = 108 Hz, 3J[13C,31P] = 2 Hz, Cipso). IG 13C NMR (63 MHz, CD3CN): δ 138.1 (s br, 5C, SCN), 134.6 (s, 12C, Cpara), 133.5−132.9 (m, 24C, Cmeta), 130.6−130.1 (m, 24C, Cortho), 128.2 (dd, 1J[13C,31P] = 108 Hz, 3J[13C,31P] = 2 Hz, 12C, Cipso). 31P NMR (121 MHz, CD3CN): δ 20.8. IR (ATR, 25 °C, 32 scans, cm−1): 3051 (w), 2073 (m), 2037 (m), 2013 (s), 1988 (s), 1975 (s), 1821 (w), 1587 (m), 1576 (w), 1481 (m), 1437 (s), 1298 (s), 1281 (s), 1265 (s), 1244 (s), 1182 (s), 1161 (m), 1109 (s), 1070 (m), 1026 (m), 997 (s), 984 (m), 953 (m), 928 (m), 922 (m), 887 (m), 856 (m), 847 (m), 825 (m), 804 (m), 762 (m), 744 (s), 721 (s), 689 (vs), 665 (s), 617 (m), 546 (vs), 530 (s). Raman (633 nm, D03, ×10, 10s, 20 acc.,

SCN acts as both a reactant and a solvent. E(NCS)3 solvates can be obtained upon recrystallizaion from THF or other solvents with donor properties. The treatment of EF3 with an excess of Me3Si−SCN in the presence of 1 always results in the formation of formal [PPN]2[E(SCN)5] salts. However, while the [Sb(NCS)5]2− ion features a square-pyramidal molecular geometry around the Sb3+ ion with five Sb−NCS bonds, the analogous bismuth species was isolated as solvate [Bi(NCS)3(SCN)2(THF)]2−, in which the Bi3+ ion sits in an octahedral molecular environment with three N-linked and two S-bound thiocyanate ions, in addition to one O atom from the THF donor solvent. All discussed antimony(III) and bismuth(III) thiocyanate complexes feature a stereochemically active lone pair, which has been discussed in the literature for antimony(III) and bismuth(III) azides as well as cyanides.36,45 Furthermore, we have presented a straightforward synthesis for hydrogen diisothiocyanate salts such as 2. This high-yielding facile synthesis begins with the synthesis of pure 1, followed by the addition of Me3Si−SCN in MeOH, which leads to the in situ formation of HSCN and Me3Si−O−Me.

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EXPERIMENTAL DETAILS

General Information. All manipulations were carried out with oxygen- and moisture-free conditions under argon using standard Schlenk or drybox techniques. MeCN was dried over CaH2 and freshly distilled prior to use. Tetrahydrofuran (THF) was dried over sodium/benzophenone and freshly distilled prior to use. n-Pentane was dried over sodium/ benzophenone/tetraglyme [tetraglyme = Me(OCH2CH2)3OMe] and freshly distilled prior to use. Trimethylsilyl isothiocyanate (ABCR) was freshly distilled and degassed prior to use. SbF3 (Fluka) and BiF3 (ABCR) were used as received. [PPN]SCN (1). [PPN]Cl (12.8 g, 22.3 mmol) was dissolved in hot water (80 °C, 100 mL). KSCN (4.3 g, 44.2 mmol) was dissolved in water (20 mL) too. Subsequently, both solutions were united. The white residue was filtered and washed with water (3 × 20 mL). After drying in air, the product was crystallized from acetone (75 mL). The product 1 was dried in vacuo and isolated with a yield of 11.36 g (85.3%). Mp: 193 °C. Elem anal. calcd (found): C, 74.48 (74.16); H, 5.07 (5.19); N, 4.69 (4.65); S, 5.37 (5.18). 1H NMR (300 MHz, CD3CN): δ 7.72−7.41 (m). 13C NMR (75 MHz, CD3CN): δ 134.6 (s, Cpara), 133.5−133.1 (m, Cmeta), 130.6−130.2 (m, Cortho), 128.2 (dd, 1J[13C,31P] = 108 Hz, 3J[13C,31P] = 2 Hz, Cipso). 31P NMR (121 MHz, CD3CN): δ 20.8. IR (ATR, 25 °C, 32 scans, cm−1): 3059 (w), 3012 (w), 2052 (m), 1587 (w), 1576 (w), 1481 (w), 1435 (m), 1410 (w), 1319 (m), 1304 (s), 1286 (m), 1273 (s), 1178 (m), 1161 (w), 1111 (s), 1076 (m), 1026 (w), 997 (m), 974 (w), 924 (w), 795 (w), 764 (m), 741 (m), 719 (s), 702 (s), 687 (s), 663 (m), 615 (w), 546 (s), 528 (vs). Raman (633 nm, D00, ×10, 20s, 20 acc., cm−1): 3172 (0), 3148 (0), 3146 (0), 3143 (0), 3089 (0), 3063 (3), 3057 (3), 3013 (0), 2989 (0), 2052 (5), 1587 (5), 1574 (1), 1193 (0), 1185 (0), 1177 (1), 1162 (0), 1159 (0), 1152 (1), 1115 (2), 1107 (3), 1025 (5), 998 (10), 728 (1), 660 (3), 613 (2), 542 (0), 485 (0), 361 (0), 278 (0), 264 (1), 249 (1), 232 (3), 222 (1). [PPN][H(NCS)2] (2). 1 (1.475 g, 2.47 mmol) and trimethylsilyl isothiocyanate (0.70 mL, 0.648 g, 4.94 mmol) were dissolved in MeCN (2 mL). Subsequently, MeOH (0.1 mL, 0.079 g, 2.47 mmol) was added and stirred for 12 h. The solvent and excess reactants were removed in vacuo. The product had a yield of 0.956 g (98.8%). Mp: 129 °C. Elem anal. Calcd (found): C, 69.60 (69.65); H, 4.76 (4.96); N, 6.49 (6.52); S, 9.78 (9.80). 1H NMR (300 MHz, CD3CN): δ 7.77−7.33 (m). 13C NMR (75 MHz, CD3CN): δ 134.6 (s, Cpara), 133.5−133.0 (m, Cmeta), 130.6−130.1 (m, Cortho), 128.2 (dd, 1 13 31 J[ C, P] = 108 Hz, 3J[13C,31P] = 2 Hz, Cipso). 31P NMR (121 MHz, CD3CN): δ 20.8. IR (ATR, 25 °C, 32 scans, cm−1): 3076 (w), 3055 (w), 2048 (s, br), 1589 (w), 1481 (w), 1435 (m), 1296 (s), 1279 (s), 1265 (s), 1184 (m), 1169 (m), 1113 (s), 1070 (m), 1024 G


Article

Inorganic Chemistry cm−1): 3058 (5), 2076 (1), 2068 (1), 2042 (2), 2026 (5), 1993 (1), 1589 (5), 1576 (1), 1440 (1), 1185 (1), 1164 (2), 1111 (3), 1030 (5), 1003 (10), 808 (1), 725 (0), 666 (4), 616 (3), 486 (3), 477 (1), 335 (1), 268 (2), 243 (3), 237 (3), 229 (1). [PPN]2[Bi(NCS)3(SCN)2·THF] (6·THF). 1 (1.683 g, 2.82 mmol) and BiF3 (0.25 g, 0.94 mmol) were stirred in MeCN (10 mL). Subsequently, trimethylsilyl isothiocyanate (1.5 mL, 1.4 g, 8.46 mmol) was added and stirred at room temperature for 16 h. After removal of the solvent, the crude product was recrystallized from a THF solution (10 mL). The product was isolated with a yield of 1.243 g (26.8%). Mp: 114 °C. Elem anal. Calcd (found): C, 59.01 (59.34); H, 4.16 (4.19); N, 5.95 (5.65); S, 9.72 (9.47). 1H NMR (300 MHz, CD3CN): δ 7.85−7.33 (m, 60H, HPh), 3.73−3.55 (m, 4H, OCH2), 1.86−1.74 (m, 4H, CH2). 13C NMR (75 MHz, CD3CN): δ 134.6 (s, Cpara), 133.5−133.1 (m, Cmeta), 130.6−130.2 (m, Cortho), 128.2 (dd, 1J[13C,31P] = 108 Hz, 3J[13C,31P] = 2 Hz, Cipso), 68.3 (s, OCH2), 26.2 (s, CH2). 31P NMR (121 MHz, CD3CN): δ 20.8. IR (ATR, 25 °C, 32 scans, cm−1): 3057 (w), 3045 (w), 2989 (w), 2114 (w), 2102 (m), 2033 (s), 1975 (m), 1944 (s), 1824 (w), 1747 (w), 1587 (w), 1481 (m), 1437 (s), 1292 (m), 1279 (m), 1248 (s), 1180 (m), 1111 (s), 1070 (m), 1036 (m), 1024 (m), 997 (s), 951 (w), 937 (m), 924 (m), 876 (m), 851 (m), 804 (m), 760 (m), 744 (s), 721 (s), 689 (vs), 667 (s), 617 (m), 552 (s). Raman (633 nm, D03, ×10, 10s, 20 acc., cm−1): 3173 (0), 3150 (0), 3059 (5), 2955 (0), 2116 (5), 2054 (1), 1980 (1), 1950 (1), 1588 (5), 1575 (1), 1441 (1), 1188 (1), 1181 (1), 1165 (1), 1158 (1), 1111 (4), 1027 (4), 1002 (10), 710 (1), 668 (4), 1617 (2), 551 (0), 545 (0), 534 (1), 508 (1), 474 (1), 372 (1), 324 (5), 298 (1), 286 (1), 268 (3), 249 (5), 236 (7), 210 (10), 111 (2).

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(2) Kö hler, H. Die Fabrikation von Cyanverbindungen Aus Tierischen Abfällen Und Produkten Der Trockenen Destillation. Die Industrie der Cyanverbindungen; Vieweg + Teubner Verlag: Wiesbaden, Germany, 1914; pp 60−101. (3) Kauffman, G. B.; Foust, G. E.; Tun, P. Pseudohalogens: A General Chemistry Laboratory Experiment. J. Chem. Educ. 1968, 45 (2), 141−146. (4) Brand, H.; Schulz, A.; Villinger, A. Modern Aspects of Pseudohalogen Chemistry: News from CN- and PN-Chemistry. Z. Anorg. Allg. Chem. 2007, 633 (1), 22−35. (5) Stopenko, V. V.; Golub, A. M.; Köhler, H. Chemistry of Pseudohalides; Elsevier: Amsterdam, The Netherlands, 1986. (6) Birckenbach, L.; Kellermann, K. Ü ber Pseudohalogene (I). Ber. Dtsch. Chem. Ges. B 1925, 58 (4), 786−794. (7) Brand, H.; Liebman, J. F.; Schulz, A.; Mayer, P.; Villinger, A. Nonlinear, Resonance-Stabilized Pseudohalides: From Alkali Methanides to Ionic Liquids of Methanides. Eur. J. Inorg. Chem. 2006, 21, 4294−4308. (8) Lö ssner, L.; Kretzschmar, A.; Peitzsch, B.; Salomon, F. Einwirkung von Phosphorchlorür Und von Benzoylchlorid Auf Rhodankalium. J. Prakt. Chem. 1873, 7 (1), 474−480. (9) Dixon, A. E. LIX. − A Form of Tautomerism Occurring amongst the Thiocyanates of Electronegative Radicles. J. Chem. Soc., Trans. 1901, 79, 541−552. (10) Dixon, A. E. XVII. - The Action of Phosphorus Trithiocyanate on Alcohol. J. Chem. Soc., Trans. 1902, 81 (168), 168−171. (11) Söderbäck, E. Studien Ü ber Das Freie Rhodan. Liebigs Ann. Chem. 1919, 419 (3), 217−322. (12) Gall, H.; Schü p pen, J. Ü ber Die Valenz-Grenze Bei Phosphorcyaniden Und Phosphorrhodaniden. Ber. Dtsch. Chem. Ges. B 1930, 63 (2), 482−487. (13) Fluck, E.; Goldmann, F. L.; Rümpler, K.-D. Pseudohalogenide Nichtmetallischer Elemente. II. Phosphor(III)-Isothiocyanat Und Phosphor(III)-Isocyanat Die Systeme PCl3/P(NCS)3, PBr3/P(NCS)3 und PCl3/P(NCO)3. Z. Anorg. Allg. Chem. 1965, 338, 52−57. (14) Sowerby, D. B. The Preparation and Properties of Some Inorganic Isothiocyanates. J. Inorg. Nucl. Chem. 1961, 22, 205−212. (15) Alonzo, G.; Consiglio, M.; Maggio, F.; Agozzino, P.; Bertazzi, N. Identification of Antimony(III) Thiocyanato Species in the Mass Spectra of Antimony Trifluoride and Ammonium Thiocyanate Mixtures. Inorg. Chim. Acta 1989, 165 (1), 7−8. (16) Saxena, R.; Gupta, S.; Rastogi, M. K. Reactions of Antimony(III) Chloride Adducts with Potassium Thiocyanate. Asian J. Chem. 1997, 9 (1), 10−16. (17) Bertazzi, N.; Alonzo, G. Synthesis, Infrared And121Sb Mössbauer Spectra of Some Antimony(III) Thiocyanate Complexes. Z. Anorg. Allg. Chem. 1989, 575 (1), 209−216. (18) Bender, G. Ueber Rhodanwismuth. Ber. Dtsch. Chem. Ges. 1887, 20 (1), 723−726. (19) Bensch, W.; Reifler, F. A.; Reller, A.; Oswald, H. R. The Crystal Structure of Di(5-Amino-3-Thione-1,2,4-Dithiazole)TrisThiocyanatobismuthate(III), (C2H2N2S3)2Bi(SCN)3. Z. Krist. Cryst. Mater. 1989, 189, 169−179. (20) Koch, G.; Ruck, M. The Layered Coordination Polymer Bi(SCN)3·1/2 H2O. Z. Anorg. Allg. Chem. 2010, 636 (11), 1987− 1990. (21) Dillon, K. B.; Platt, A. W. G. Cyano- and ThiocyanatoDerivatives of the Hexachlorophosphate Ion (PCl6−). J. Chem. Soc., Dalton Trans. 1982, 7, 1199−1204. (22) Dillon, K. B.; Platt, A. W. G. Azido- and ThiocyanatoDerivatives of Some Chlorofluorophosphate(V) Ions. J. Chem. Soc., Dalton Trans. 1983, 6, 1159−1164. (23) Kapoor, R.; Wadhawan, P.; Kapoor, P. Preparation, Properties, and Characterization of Methanesulfonato Complexes of Arsenic(III), Antimony (III), and Bismuth(III). Can. J. Chem. 1987, 65 (6), 1195− 1199. (24) Forster, G. E.; Begley, M. J.; Sowerby, D. B. Phenylantimony(Iii) Dithiocyanate and the Crystal Structure of K[SbPh(SCN)3]. J. Chem. Soc., Dalton Trans. 1995, 7, 1173−1176.

ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.9b00378. Details of the syntheses along with all experimental data including all spectra (PDF) Accession Codes

CCDC 1895144−1895151 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Axel Schulz: 0000-0001-9060-7065 Alexander Villinger: 0000-0002-0868-9987 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors thank the Deutsche Forschungsgemeinschaft (DFG SCHU 1170/9-2), especially the priority program SPP 1708, for financial support. We thank Dr. D. Michalik (University of Rostock) for measurement of the NMR spectra.

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REFERENCES

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Heavy Neutral and Anionic Pnictogen Thiocyanates - Inorganic

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