Chlorido[3,3′-dibutyl-5,5′-(pyridine-2,6-di­yl)dipyrazol-1-ido]gold(III)

Hashmi, A.S.K.; Lothschütz, C.; Rominger, F.

doi:10.1107/S1600536809050995

metal-organic compounds

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ISSN: 2056-9890

Volume 66| Part 1| January 2010| Page m64

doi:10.1107/S1600536809050995

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Chlorido[3,3′-dibutyl-5,5′-(pyridine-2,6-diyl)dipyrazol-1-ido]gold(III)

A. Stephen K. Hashmi,^a ^* Christian Lothschütz ^a and Frank Rominger ^a

^aOrganisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
^*Correspondence e-mail: hashmi@hashmi.de

(Received 13 November 2009; accepted 26 November 2009; online 16 December 2009)

The Au atom in the C2-symmetric pincer-type title complex, [AuCl(C₁₉H₂₃N₅)], is in the +3 oxidation state. The ligand is composed of one pyridine unit and two n-butyl-substituted pyrazoles (pyrz). Both pyrazoles are deprotonated, thus forming a neutral compound. To the best of our knowledge, this is the first Au^III–bispyrazolate complex. According to the special geometry in the N,N′,N′′-tridentate ligand, containing two five-membered heterocycles, the complex deviates from an ideal square-planar coordination geometry; the N_pyrz—Au—N_pyrz angle is 160.8 (3)°, indicating a distortion of nearly 20°.

Related literature

For the importance of gold catalysis, see: Hashmi & Hutchings (2006a ,b ); Hashmi (2007 ). For the role of the gold(I) oxidation state, see: Ito et al. (1986 ) and for the use of gold(III) pre-catalysts, see: Hashmi et al. (2004a ,b ).

Experimental

Crystal data

[AuCl(C₁₉H₂₃N₅)]
M_r = 553.84
Monoclinic, P 2₁ /c
a = 9.0003 (3) Å
b = 24.2220 (7) Å
c = 9.3042 (3) Å
β = 101.372 (1)°
V = 1988.54 (11) Å³
Z = 4
Mo Kα radiation
μ = 7.55 mm⁻¹
T = 200 K
0.16 × 0.04 × 0.04 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan SADABS (Sheldrick, 2008b ) T_min = 0.378, T_max = 0.752
19560 measured reflections
4539 independent reflections
3103 reflections with I > 2σ(I)
R_int = 0.091

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.089
S = 1.07
4539 reflections
235 parameters
H-atom parameters constrained
Δρ_max = 0.91 e Å⁻³
Δρ_min = −1.01 e Å⁻³

Data collection: SMART (Siemens, 1996 ); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008a ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809050995/hg2593sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809050995/hg2593Isup2.hkl

checkCIF report

Comment top

Catalysis of organic reactions by gold complexes has become a very important area of research in the past decade (Hashmi & Hutchings, 2006a, 2006b; Hashmi, 2007). While the field is dominated by gold(I) complexes (Ito et al., 1986), the use of gold(III) pre-catalysts is also of interest (Hashmi et al., 2004a, 2004b). Here we report the structural details of a new representative of the gold(III) pre-catalysts. The main feature of this structure is the ring strain of the two 5-membered metallacycles that were built up by the pincer ligand and the gold center. The theoretical sum of the bond angles in these flat 5-membered metallacycles is 540.0°, as it was observed in both cases. For a hypothetic strain-free (ring-opened) molecule simple geometrical considerations result an angle sum of about 582° (90° at Au1, 120° at N1, C2, C6, and 126° at C11, N12 C21, N22). The required adaption of 42° is achieved by bending the bond angles (mean values over both rings) at Au1 (9.7°), N1 (2.4°), C2/C6 (7.6°), C11/C21 (10.3°), and N12/N22 (12.0°). As expected the bending at the pyridin nitrogen atom N1 is by far least, as the aromatic ring itself is rigid and cannot bend on two sides simultaneously.

Related literature top

For the importance of gold catalysis, see: Hashmi & Hutchings (2006a,b); Hashmi (2007). For the role of the gold(I) oxidation state, see: Ito et al. (1986) and for the use of gold(III) pre-catalysts, see: Hashmi et al. (2004a, 2004b).

Experimental top

2,6-bis(5-butyl-1H-pyrazol-3-yl)pyridine (200 mg, µmol) was dissolved in acetone (5 ml). After this HAuCl₄*xH₂O (248 mg, 618 µmol, 49% metal content) in acetonitrile (3 ml) and NaOH (2.5 M in H₂O, 741 µl) were added consecutively. The mixture was warmed to 60 °C for 20 min, during this time the initially formed yellow precipitate dissolved. The mixture was subjected to hot filtration and the solvent was removed under reduced pressure. The crude complex was purified by recrystallization from acetone to yield the title compound as red crystals (96.0 mg, 173 µmol, 28%). The compound is stable at RT in air.

¹H NMR (300 MHz, acetone): δ=0.93 (t, J=7.3 Hz, 6H, CH₃), 1.4 (dm, J=8.5, 7.1 Hz, 4H, CH₂), 1.65 (m, 4H, CH₂), 2.66 (t, J=7.5 Hz, 4H, CH₂), 7.71 (d, J=7.9 Hz, 2H, ArH), 8.25 (t, J=7.9 Hz, 1H, ArH); ¹³C NMR (75 MHz, acetone): δ = 14.27, 23.13, 32.87, 106.97, 116.38 (no further signals observed, one signal overlapping with solvent at about 29 p.p.m.)

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXTL (Sheldrick, 2008a); program(s) used to refine structure: SHELXTL (Sheldrick, 2008a); molecular graphics: SHELXTL (Sheldrick, 2008a); software used to prepare material for publication: SHELXTL (Sheldrick, 2008a).

Figures top

Fig. 1. Thermal ellipsoid representation of the title compound. Displacement ellipsoids were plotted at 50% probability level.

Chlorido[3,3'-dibutyl-5,5'-(pyridine-2,6-diyl)dipyrazol-1-ido]gold(III) top

Crystal data top

[AuCl(C₁₉H₂₃N₅)]	Z = 4
M_r = 553.84	F(000) = 1072
Monoclinic, P2₁/c	D_x = 1.850 Mg m⁻³
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 9.0003 (3) Å	Cell parameters from 6701 reflections
b = 24.2220 (7) Å	µ = 7.55 mm⁻¹
c = 9.3042 (3) Å	T = 200 K
β = 101.372 (1)°	Polyhedron, orange
V = 1988.54 (11) Å³	0.16 × 0.04 × 0.04 mm

Data collection top

Bruker SMART CCD diffractometer	4539 independent reflections
Radiation source: fine-focus sealed tube	3103 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.091
ω scans	θ_max = 27.5°, θ_min = 1.7°
Absorption correction: multi-scan SADABS (Sheldrick, 2008b)	h = −11→11
T_min = 0.378, T_max = 0.752	k = −31→31
19560 measured reflections	l = −12→12

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.089	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0241P)² + 2.5681P] where P = (F_o² + 2F_c²)/3
4539 reflections	(Δ/σ)_max = 0.001
235 parameters	Δρ_max = 0.91 e Å⁻³
0 restraints	Δρ_min = −1.01 e Å⁻³

Crystal data top

[AuCl(C₁₉H₂₃N₅)]	V = 1988.54 (11) Å³
M_r = 553.84	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 9.0003 (3) Å	µ = 7.55 mm⁻¹
b = 24.2220 (7) Å	T = 200 K
c = 9.3042 (3) Å	0.16 × 0.04 × 0.04 mm
β = 101.372 (1)°

Data collection top

Bruker SMART CCD diffractometer	4539 independent reflections
Absorption correction: multi-scan SADABS (Sheldrick, 2008b)	3103 reflections with I > 2σ(I)
T_min = 0.378, T_max = 0.752	R_int = 0.091
19560 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.089	H-atom parameters constrained
S = 1.07	Δρ_max = 0.91 e Å⁻³
4539 reflections	Δρ_min = −1.01 e Å⁻³
235 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Au1	0.28448 (3)	0.481560 (12)	0.61190 (3)	0.03110 (10)
Cl1	0.3449 (3)	0.44522 (9)	0.8400 (2)	0.0514 (6)
N1	0.2300 (7)	0.5101 (2)	0.4082 (6)	0.0347 (15)
C2	0.1273 (8)	0.5513 (3)	0.3826 (8)	0.0328 (17)
C3	0.0815 (9)	0.5696 (3)	0.2393 (8)	0.040 (2)
H3	0.0069	0.5977	0.2156	0.048*
C4	0.1478 (11)	0.5458 (3)	0.1317 (9)	0.050 (2)
H4	0.1166	0.5578	0.0331	0.060*
C5	0.2585 (10)	0.5050 (3)	0.1635 (9)	0.044 (2)
H5	0.3070	0.4906	0.0897	0.053*
C6	0.2952 (8)	0.4865 (3)	0.3063 (8)	0.0344 (18)
C11	0.0767 (8)	0.5693 (3)	0.5158 (7)	0.0316 (18)
N12	0.1375 (7)	0.5411 (2)	0.6419 (6)	0.0319 (14)
N13	0.0917 (6)	0.5633 (2)	0.7583 (6)	0.0293 (14)
C14	−0.0014 (8)	0.6050 (3)	0.7037 (8)	0.0311 (17)
C15	−0.0165 (8)	0.6099 (3)	0.5537 (8)	0.0328 (18)
H15	−0.0773	0.6355	0.4906	0.039*
C16	−0.0734 (9)	0.6395 (3)	0.8036 (8)	0.040 (2)
H16A	0.0009	0.6458	0.8958	0.048*
H16B	−0.1601	0.6190	0.8284	0.048*
C17	−0.1289 (9)	0.6948 (3)	0.7383 (9)	0.042 (2)
H17A	−0.2064	0.6882	0.6485	0.050*
H17B	−0.0429	0.7142	0.7085	0.050*
C18	−0.1964 (9)	0.7326 (3)	0.8389 (9)	0.048 (2)
H18A	−0.1224	0.7370	0.9322	0.057*
H18B	−0.2881	0.7149	0.8618	0.057*
C19	−0.2390 (11)	0.7898 (4)	0.7739 (11)	0.066 (3)
H19A	−0.1466	0.8108	0.7709	0.098*
H19B	−0.2990	0.8094	0.8349	0.098*
H19C	−0.2986	0.7858	0.6743	0.098*
C21	0.3986 (9)	0.4418 (3)	0.3670 (8)	0.041 (2)
N22	0.4106 (7)	0.4319 (3)	0.5137 (7)	0.0386 (16)
N23	0.5062 (8)	0.3898 (3)	0.5598 (8)	0.0465 (18)
C24	0.5559 (9)	0.3730 (3)	0.4398 (11)	0.049 (2)
C25	0.4926 (9)	0.4040 (3)	0.3161 (10)	0.049 (2)
H25	0.5099	0.4002	0.2191	0.058*
C26	0.6668 (11)	0.3245 (4)	0.4558 (13)	0.071 (3)
H26A	0.7227	0.3261	0.3744	0.085*
H26B	0.7416	0.3291	0.5484	0.085*
C27	0.6011 (12)	0.2719 (4)	0.4563 (15)	0.093 (4)
H27A	0.5352	0.2656	0.3592	0.112*
H27B	0.5353	0.2718	0.5299	0.112*
C28	0.7134 (12)	0.2229 (5)	0.4898 (16)	0.094 (4)
H28A	0.7856	0.2244	0.4221	0.113*
H28B	0.7723	0.2265	0.5911	0.113*
C29	0.6347 (14)	0.1689 (5)	0.4739 (15)	0.114 (5)
H29A	0.5526	0.1693	0.5293	0.171*
H29B	0.7069	0.1396	0.5119	0.171*
H29C	0.5924	0.1620	0.3701	0.171*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Au1	0.03813 (17)	0.03202 (16)	0.02527 (15)	0.00177 (16)	0.01141 (11)	−0.00274 (16)
Cl1	0.0686 (15)	0.0563 (14)	0.0304 (11)	0.0218 (12)	0.0125 (10)	0.0075 (10)
N1	0.051 (4)	0.032 (4)	0.024 (3)	−0.006 (3)	0.015 (3)	−0.003 (3)
C2	0.039 (5)	0.034 (4)	0.029 (4)	−0.008 (4)	0.016 (3)	−0.001 (3)
C3	0.053 (5)	0.040 (5)	0.026 (4)	0.001 (4)	0.005 (4)	0.005 (4)
C4	0.079 (7)	0.041 (5)	0.032 (5)	−0.014 (5)	0.019 (5)	−0.003 (4)
C5	0.072 (6)	0.039 (5)	0.030 (4)	−0.021 (4)	0.031 (4)	−0.012 (4)
C6	0.045 (5)	0.040 (5)	0.024 (4)	−0.014 (4)	0.021 (3)	−0.010 (4)
C11	0.043 (5)	0.034 (4)	0.019 (4)	−0.003 (3)	0.010 (3)	0.008 (3)
N12	0.038 (4)	0.033 (3)	0.027 (3)	0.007 (3)	0.013 (3)	−0.002 (3)
N13	0.029 (3)	0.039 (4)	0.022 (3)	0.001 (3)	0.010 (3)	−0.008 (3)
C14	0.032 (4)	0.037 (5)	0.024 (4)	0.000 (3)	0.007 (3)	0.000 (3)
C15	0.041 (5)	0.035 (4)	0.021 (4)	0.005 (4)	0.003 (3)	0.002 (3)
C16	0.041 (5)	0.048 (5)	0.031 (4)	0.005 (4)	0.006 (4)	−0.003 (4)
C17	0.045 (5)	0.041 (5)	0.038 (5)	0.011 (4)	0.004 (4)	−0.006 (4)
C18	0.051 (6)	0.050 (5)	0.039 (5)	0.009 (4)	0.003 (4)	−0.014 (4)
C19	0.080 (7)	0.042 (6)	0.067 (7)	0.018 (5)	−0.005 (5)	−0.018 (5)
C21	0.054 (5)	0.041 (5)	0.031 (5)	−0.012 (4)	0.020 (4)	−0.014 (4)
N22	0.046 (4)	0.032 (4)	0.041 (4)	0.002 (3)	0.018 (3)	−0.007 (3)
N23	0.047 (4)	0.034 (4)	0.067 (5)	0.001 (3)	0.031 (4)	0.001 (4)
C24	0.046 (5)	0.031 (5)	0.079 (7)	−0.007 (4)	0.036 (5)	−0.016 (5)
C25	0.050 (6)	0.040 (5)	0.064 (6)	−0.007 (4)	0.031 (5)	−0.016 (5)
C26	0.075 (7)	0.041 (6)	0.106 (9)	−0.002 (5)	0.041 (6)	−0.018 (6)
C27	0.055 (7)	0.064 (8)	0.170 (13)	0.009 (6)	0.042 (7)	0.025 (8)
C28	0.062 (7)	0.071 (9)	0.152 (12)	0.032 (6)	0.027 (7)	0.030 (8)
C29	0.104 (11)	0.092 (11)	0.141 (13)	0.044 (9)	0.011 (9)	0.018 (10)

Geometric parameters (Å, º) top

Au1—N1	1.985 (6)	C17—H17B	0.9900
Au1—N22	1.994 (6)	C18—C19	1.529 (11)
Au1—N12	2.014 (6)	C18—H18A	0.9900
Au1—Cl1	2.263 (2)	C18—H18B	0.9900
N1—C6	1.338 (8)	C19—H19A	0.9800
N1—C2	1.349 (9)	C19—H19B	0.9800
C2—C3	1.389 (10)	C19—H19C	0.9800
C2—C11	1.469 (9)	C21—N22	1.369 (9)
C3—C4	1.387 (11)	C21—C25	1.390 (11)
C3—H3	0.9500	N22—N23	1.349 (9)
C4—C5	1.394 (12)	N23—C24	1.346 (10)
C4—H4	0.9500	C24—C25	1.398 (12)
C5—C6	1.379 (10)	C24—C26	1.530 (12)
C5—H5	0.9500	C25—H25	0.9500
C6—C21	1.466 (11)	C26—C27	1.403 (12)
C11—N12	1.374 (9)	C26—H26A	0.9900
C11—C15	1.383 (10)	C26—H26B	0.9900
N12—N13	1.345 (7)	C27—C28	1.551 (13)
N13—C14	1.346 (9)	C27—H27A	0.9900
C14—C15	1.381 (9)	C27—H27B	0.9900
C14—C16	1.490 (10)	C28—C29	1.482 (15)
C15—H15	0.9500	C28—H28A	0.9900
C16—C17	1.515 (10)	C28—H28B	0.9900
C16—H16A	0.9900	C29—H29A	0.9800
C16—H16B	0.9900	C29—H29B	0.9800
C17—C18	1.519 (10)	C29—H29C	0.9800
C17—H17A	0.9900

N1—Au1—N22	80.1 (3)	C17—C18—C19	113.6 (7)
N1—Au1—N12	80.6 (2)	C17—C18—H18A	108.8
N22—Au1—N12	160.8 (3)	C19—C18—H18A	108.8
N1—Au1—Cl1	177.47 (18)	C17—C18—H18B	108.8
N22—Au1—Cl1	98.2 (2)	C19—C18—H18B	108.8
N12—Au1—Cl1	101.06 (18)	H18A—C18—H18B	107.7
C6—N1—C2	124.9 (6)	C18—C19—H19A	109.5
C6—N1—Au1	117.9 (5)	C18—C19—H19B	109.5
C2—N1—Au1	117.3 (5)	H19A—C19—H19B	109.5
N1—C2—C3	118.0 (7)	C18—C19—H19C	109.5
N1—C2—C11	112.7 (6)	H19A—C19—H19C	109.5
C3—C2—C11	129.2 (7)	H19B—C19—H19C	109.5
C4—C3—C2	118.1 (8)	N22—C21—C25	106.9 (8)
C4—C3—H3	120.9	N22—C21—C6	115.6 (6)
C2—C3—H3	120.9	C25—C21—C6	137.5 (8)
C3—C4—C5	122.2 (8)	N23—N22—C21	111.6 (6)
C3—C4—H4	118.9	N23—N22—Au1	134.0 (5)
C5—C4—H4	118.9	C21—N22—Au1	114.3 (5)
C6—C5—C4	117.5 (7)	C24—N23—N22	105.1 (7)
C6—C5—H5	121.3	N23—C24—C25	111.9 (7)
C4—C5—H5	121.3	N23—C24—C26	117.9 (9)
N1—C6—C5	119.2 (8)	C25—C24—C26	130.2 (8)
N1—C6—C21	112.1 (6)	C21—C25—C24	104.5 (8)
C5—C6—C21	128.7 (7)	C21—C25—H25	127.8
N12—C11—C15	107.2 (6)	C24—C25—H25	127.8
N12—C11—C2	115.8 (7)	C27—C26—C24	115.5 (9)
C15—C11—C2	137.0 (7)	C27—C26—H26A	108.4
N13—N12—C11	110.8 (6)	C24—C26—H26A	108.4
N13—N12—Au1	135.4 (5)	C27—C26—H26B	108.4
C11—N12—Au1	113.6 (5)	C24—C26—H26B	108.4
N12—N13—C14	105.2 (5)	H26A—C26—H26B	107.5
N13—C14—C15	112.1 (6)	C26—C27—C28	115.9 (9)
N13—C14—C16	120.0 (6)	C26—C27—H27A	108.3
C15—C14—C16	127.9 (7)	C28—C27—H27A	108.3
C14—C15—C11	104.6 (6)	C26—C27—H27B	108.3
C14—C15—H15	127.7	C28—C27—H27B	108.3
C11—C15—H15	127.7	H27A—C27—H27B	107.4
C14—C16—C17	113.3 (6)	C29—C28—C27	112.1 (9)
C14—C16—H16A	108.9	C29—C28—H28A	109.2
C17—C16—H16A	108.9	C27—C28—H28A	109.2
C14—C16—H16B	108.9	C29—C28—H28B	109.2
C17—C16—H16B	108.9	C27—C28—H28B	109.2
H16A—C16—H16B	107.7	H28A—C28—H28B	107.9
C16—C17—C18	115.2 (7)	C28—C29—H29A	109.5
C16—C17—H17A	108.5	C28—C29—H29B	109.5
C18—C17—H17A	108.5	H29A—C29—H29B	109.5
C16—C17—H17B	108.5	C28—C29—H29C	109.5
C18—C17—H17B	108.5	H29A—C29—H29C	109.5
H17A—C17—H17B	107.5	H29B—C29—H29C	109.5

Experimental details

Crystal data
Chemical formula	[AuCl(C₁₉H₂₃N₅)]
M_r	553.84
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	200
a, b, c (Å)	9.0003 (3), 24.2220 (7), 9.3042 (3)
β (°)	101.372 (1)
V (Å³)	1988.54 (11)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	7.55
Crystal size (mm)	0.16 × 0.04 × 0.04

Data collection
Diffractometer	Bruker SMART CCD diffractometer
Absorption correction	Multi-scan SADABS (Sheldrick, 2008b)
T_min, T_max	0.378, 0.752
No. of measured, independent and observed [I > 2σ(I)] reflections	19560, 4539, 3103
R_int	0.091
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.089, 1.07
No. of reflections	4539
No. of parameters	235
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.91, −1.01

Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SHELXTL (Sheldrick, 2008a).

Acknowledgements

Gold salts were donated by Umicore AG & Co. KG.

References

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