Synthesis and structure of gold complexes [ p-Tol 4Sb][ p-TolAuCl 3] and [ p-Tol 4Sb][AuCl 4]

Synthesis and structure of complex compounds of gold, containing [AuHal₄] ^- anions in their composition, were mentioned in the literature [1-5]. In the present paper the synthesis and structure of gold complexes [ p -Tol 4 Sb][AuCl 4 ] and [ p -Tol 4 Sb][ p -TolAuCl 3 ] are described.

Experimental

Synthesis of [ р -Тоl 4 Sb]⁺[ р -ТоlAuCl 3 ]^- (1). Tetra- para -tolylantimony chloride 0.250 g (0.48 mmol) and aurichlorohydric acid tetrahydrate 0.197 g (0.48 mmol) were dissolved in 10 mL acetone, then 5 ml toluene was added. The solution was left to stand for 12 h at 20 ° C. After evaporation of the solvent 0.287 g (68%) of tetra- para -tolylantimony para -tolyltrichloroaurate was obtained (mp 156 ° C). IR spectrum (v, cm ^{- 1}): 484, 587, 800, 1007, 1072, 1194, 1305, 1401, 1492, 1588, 1627, 1905, 2926. Found, %: С 47,38, Н 4,03. Calculated for C 35 H 35 AuCl 3 , %: С 47,72, Н 3,98.

Synthesis of [ р -Тоl 4 Sb]⁺[AuCl 4 ]^- (2). a) The mixture of tetra-para-tolylantimony chloride 0.137 g (0.26 mmol) and and aurichlorohydric acid tetrahydrate 0.108 g (0.26 mmol) in 10 mL acetone stood for 24 h at room temperature. The solvent was evaporated. The yield is 0.205 g (95%) of tetra- para -tolylantimony tetra- para -chloroaurate with decomposition temperature 148-150 ° C. IR spectrum (v, cm ^{- 1}): 483, 529, 585, 633, 697, 809, 1101, 1040, 1066, 1123, 1190, 1212, 1313, 1396, 1444, 1493, 1589, 1708, 2863, 2918, 2953, 3045. Found, %: С 40.52, Н 3.49. Calculated for C 28 H 28 SbAuCl 4 , %: С 40.75, Н 3.40.

• b) The mixture of penta- para -tolylantimony 0.181 g (0.31 mmol) and aurichloric acid tetrahydrate 0.129 g (0.31 mmol) in 10 mL acetone stood for 24 h at room temperature. The solvent was evaporated. The yield is 0.232 g (90%) of pale yellow tetra- para -tolylantimony tetrachloroaurate, the melting point and IR spectrum coincide with tetra- para -tolylantimony tetrachloroaurate obtained according to method a. Found: %: С 40.54, Н 3.52. Calculated for C 28 H 28 SbAuCl 4 , %: С 40.75, Н 3.40.

IR spectra were recorded on the Bruker Tensor 27 in KBr pellets.

The X-ray diffraction analyses of crystals 1 and 2 were performed on the Bruker D8 QUEST automatic four-circle diffractometer (Mo K „ -emission, X = 0.71073 A, graphite monochromator). The data were collected and analyzed, the unit cell parameters were refined, and the absorption correction was applied using the SMART and SAINT-Plus programs [6]. All calculations for structure determination and refinement were performed using the SHELXL/PC programs [7]. The structures were determined by the direct method and refined by the least-squares method in the anisotropic approximation for nonhydrogen atoms.

The main crystallographic data and refinement results for the structures are listed in Table 1. The selected bond lengths and bond angles are given in Table 2.

The full tables of atomic coordinates, bond lengths, and bond angles were deposited with the Cambridge Crystallographic Data Centre (CCDC 1000139 for 1, CCDC 1000140 for 2; ; .

Table 1

Crystallographic data, the experimental and structure refinement parameters for compounds 1, 2

Parameter	Value
	1	2
М	880.70	825.02
Crystal system	Monoclinic	Monoclinic
Space group	P2 1 /n	P2 1 /n
a , Å	12.748(5)	12.7962(5)
b , Å	14.941(5)	14.8701(5)
c, Å	18.19 8(10)	16.1167(5)
α , град	90.00	90.00
β , град	102.87(4)	101.8270(10)
γ , град	90.00	90.00
V , Å3	3379(3)	3001.59(18)
Z	4	4
ρ (calcd.), г/см3	1.731	1.826
µ , mm–1	5.395	6.153
F (000)	1704.0	1576.0
Crystal size, mm	0.54 × 0.36 × 0.34	0.99 × 0.61 × 0.5
2 θ Range of data collection, deg	4.48 - 62.1°	6.16 - 60.1°
Range of refraction indices	–18 ≤ h ≤ 18, –16 ≤ k ≤ 21, –25 ≤ l ≤ 26	–17 ≤ h ≤ 13, –20 ≤ k ≤ 7, –22 ≤ l ≤ 20
Measured reflections	38599	7733
Independent reflections	10659 (R int = 0.0819)	5051 (R int = 0.0298)
Refinement variables	366	311
GOOF	1.011	0.993
R -factors for F2 > 2 σ (F2)	R 1 = 0.0653, wR 2 = 0.1145	R 1 = 0.0416, wR 2 = 0.0913
R -factors for all reflections	R 1 = 0.1352, wR 2 = 0.1342	R 1 = 0.1046, wR 2 = 0.1137
Residual electron density (min/max), e/A3	2.06/–0.82	0.55/–0.85

Table 2

Selected bond lengths ( d ) and bond angles ( ω ) in the structures of compounds 1, 2

Bond d, Å		Angle ω , deg
1
Au(1) - Cl(1)	2.286(2)		Cl(1)Au(1)Cl(2)	176.68(8)
Au(1) - Cl(2)	2.292(2)		C(41)Au(1)Cl(3)	175.59(19)
Au(1) - Cl(3)	2.389(2)		C(1)Sb(1)C1(1)	110.6(3)
Au(1) - C(41)	2.028(7)		C(1)Sb(1)C(21)	106.1(3)
Sb(1) - C(1)	2.094(6)		C(21)Sb(1)C(11)	112.7(3)
Sb(1) - C(11)	2.097(6)		C(31)Sb(1)C(1)	111.3(3)
Sb(1) - C(21)	2.095(7)		C(31)Sb(1)C(11)	108.1(3)
Sb(1) - C(31)	2.091(7)		C(31)Sb(1)C(21)	108.0(3)
2
Au(1) - Cl(1)	2.266(3)		Cl(1)Au(1)Cl(2)	90.74(13)
Au(1) - Cl(2)	2.269(3)		Cl(1)Au(1)Cl(3)	89.58(13)
Au(1) - Cl(3)	2.278(3)		Cl(2)Au(1)Cl(3)	177.61(13)
Au(1) - Cl(4)	2.248(3)		Cl(4)Au(1)Cl(1)	177.24(16)

Organometallic chemistry

Table 2 (end)

Bond d, Å		Angle to , deg
Sb(1) - C(1)	2.076(9)	Cl(4)Au(1)Cl(2)	89.17(13)
Sb(1) - C(11)	2.095(8)	Cl(4)Au(1)Cl(3)	90.62(13)
Sb(1) - C(31)	2.097(9)	C(1)Sb(1)C1(1)	109.5(3)
Sb(1) - C(21)	2.086(8)	C(1)Sb(1)C(31)	111.5(4)
C(1) - C(2)	1.391(13)	C(1)Sb(1)C(21)	109.4(3)
C(1) - C(7)	1.370(12)	C(11)Sb(1)C(31)	106.5(3)
C(2) - C(3)	1.375(16)	C(21)Sb(1)C(11)	111.2(3)
C(4) - C(5)	1.501(16)	C(21)Sb(1)C(31)	108.6(4)

Results and Discussion

It is known that the product of pentaphenylantimony reaction with aurichlorohydric acid (hydrogen tetrachloroaurate (III)) at 20 ° С in acetone is tetraphenylantimony tetrachloroaurate, separated from the reaction mixture with 84 % yield [2].

We have found that in similar conditions the interaction of aurichlorohydric acid, obtained by dissolving jewelry gold in aqua regis, with tetra- para -tolylantimony chloride runs with formation of tetra- para -tolylantimony para -tolyltrichloroaurate ( 1 ):

p -To^SbCl + H[AuCl 4 ] + TolH ^ [ p -Tol 4 Sb]⁺[ p -TolAuCy ^-

If chemically pure aurichlorohydric acid is used, such an unusual transmetalation reaction between antimony and gold compounds is not observed. In this case the formation of tetra- para -tolylantimony tetrachloroaurate ( 2 ) occurs:

p -To^SbCl + HAuCLJ • 4 H 2 O ^ [ p -ToUSbJ + LAuCLJ ^- + HCl + 4 H 2 O

Complex 2 has also been obtained from penta- para -tolylantimony and aurichlorohydric acid: p -To^Sb + H[AuCl 4 ] • 4 H 2 O ^ [ p -Tol 4 Sb]⁺[AuCl 4 ] ^- + TolH + 4 H 2 O

It is obvious that the presence of impurities in the initial jewelry gold and, consequentially, in the used acid affects the direction of the chemical reaction between aurichlorohydric acid and tetra- para -tolylantimony chloride.

According to the X-ray analysis data, the crystal of complex 1 consists of tetra- para -tolylstibonium tetrahedral cations and [ p -TolAuCl 3 ] ^- square-planar anions (Fig. 1).

Fig. 1. The structure of the molecule of compound 1

In crystal 1 tetra- para -tolylstibonium tetrahedral cations (Sb-C 2.091(7) - 2.097(6) A, CSbC 106.1(3) °- 112.7(3) ° ) are present, as well as [ p -TolAuCl₃] ^- anions of square-planar structure (Au - Cl 2.286(2) - 2.389(2) A, Au - C 2.028(7) A, ClAuCl 89.92(9) ° , 92.42(9) ° , 176.68(8) ° , CAuCl 88.27(18) ° , 89.57(18) ° , 175.59(19) ° ). In crystal 2 the geometric characteristics of cations (Sb - C 2.076(7) - 2.097(9), CSbC 106.5(3) °- 111.5(4) ° ) and [AuCl 4 ] ^- square-planar anions (Au - Cl 2.248(3) - 2.278(3) A, ClAuCl 89.17(9) °- 90.74(13) ° , 177.24(16) ° , 177.61(13) ° ) (Fig. 2, Table 2) are similar to those found in 1 .

Fig. 2. The structure of complex 2

The structural organization in crystals I and II is caused by weak interionic hydrogen bonds. At that in I the single interionic contact is observed: ortho -H Ph (16)∙∙∙Cl(1) (2.92 Å). In complex II each anion is bonded with four cations through Cl --- H bonds, formed with the use of all four chlorine atoms and ortho -, meta - and methyl hydrogen atoms of tolyl substituents (2.81 - 2.88 A) (Fig. 3).

Fig. 3. Interionic hydrogen bonds in the crystal of complex 2

Organometallic chemistry

Conclusions

Thus, the ionic complexes of gold with tetra- para -stibonium tetrahedral cation and [ p -TolAuCl₃] ^- and [AuCl 4 ] square-planar anions have been synthesized and structurally described for the first time. The first example of transmetalation reaction with the use of antimony and gold compounds has been described.