Crystal structure of bis­{N-[(di­ethyl­amino)­dimethyl­sil­yl]anilido-κ² N,N′}zinc

Abstract

The title zinc amide, [Zn(C₁₂H₂₁N₂Si)₂], was prepared by the metathetical reaction of [LiN(SiMe₂NEt₂)(C₆H₅)]₂ with zinc dichloride. It is mononuclear and the mol­ecule is generated by twofold rotation symmetry. The central Zn^II atom is N,N′-chelated by each of the two N-silylated anilide ligands in a highly distorted tetra­hedral environment. Two N—Si—N ligands are arranged in a cis fashion around the Zn^II atom. The Zn—N_amine bonds [2.2315 (12) Å] are much longer than the Zn—N_anilide bonds [1.9367 (11) Å].

Related literature  

For related compounds which show linear and tetra­hedral coordination, see: Schumann et al. (2000 ▸). For applications of zinc amides, see: Armstrong et al. (2002 ▸) and for their utility in MOVCD, see Maile & Fischer (2005 ▸). For a related zinc amide with a dimethylanilide ligand instead of an anilide ligand, see: Chen et al. (2007 ▸).

Experimental  

Crystal data  

• [Zn(C₁₂H₂₁N₂Si)₂]

• M _r = 508.19

• Orthorhombic,

• a = 29.7954 (12) Å

• b = 21.3566 (8) Å

• c = 8.5844 (3) Å

• V = 5462.5 (4) ų

• Z = 8

• Mo Kα radiation

• μ = 1.01 mm⁻¹

• T = 200 K

• 0.20 × 0.15 × 0.15 mm

Data collection  

• Bruker SMART area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▸) T _min = 0.824, T _max = 0.864

• 12927 measured reflections

• 3296 independent reflections

• 3153 reflections with I > 2σ(I)

• R _int = 0.023

Refinement  

• R[F ² > 2σ(F ²)] = 0.019

• wR(F ²) = 0.051

• S = 1.12

• 3296 reflections

• 147 parameters

• 1 restraint

• H-atom parameters constrained

• Δρ_max = 0.23 e Å⁻³

• Δρ_min = −0.23 e Å⁻³

• Absolute structure: Flack (1983 ▸), 1484 Friedel pairs

• Absolute structure parameter: 0.028 (7)

Data collection: SMART (Bruker, 2000 ▸); cell refinement: SAINT (Bruker, 2000 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: SHELXTL/PC (Sheldrick, 2008 ▸); software used to prepare material for publication: SHELXL97.

Supplementary Material

CCDC reference: 1439385

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

S1. Comment

Zinc amides were good transamination reagents and useful precusors for preparing the zinc thin film through the MOVCD method (Amstrong et al., 2002; Maile et al., 2005).

The title compound was prepared by metathetical reaction of [LiN(SiMe₂NEt₂)(C₆H₅)]₂ with zinc dichloride. It is monomeric and similar to the reported bis[(N-trimethylsilyl)2,6-dimethylanilido]zinc (Schumann et al., 2000). The ligand fixes Zn center with the N—Si—N chelating unit, giving an N—Zn—N bite angle of 76.98°. The N—Si—N group is presumed to be a "quasi" conjugated system owing to d—π interaction between Si and N atoms, but is much more flexible in contrast to the rigid N—C—N chelating unit in the amidinate ligand. The Zn—N_anilide bonds are in the normal range. The Zn—N_amine bonds are about 0.3 Å longer than the Zn—N_anilide bonds. Two N—Si—N ligands are arranged in a cis fashion around Zn, composing a highly distorted tetrahedral environment. The situation is quite different from an analgous zinc amide with the similar ligand, in which the two ligands are trans to each other (Chen et al., 2007). Two types of ligands have slightly different steric effect.

S2. Experimental

A solution of LiBuⁿ (2.2 M, 2.27 ml, 5.0 mmol) in hexane was slowly added into a solution of [NH(SiMe₂NEt₂)(C₆H₅)]₂ (1.14 g, 5.0 mmol) in Et₂O (30 ml) at 273 K by syringe. The mixture was stirred at room temperature for five hours and then ZnCl₂ (0.56 g, 2.5 mmol) was added at 273 K. The resulting solution was stirred at room temperature overnight. The filtrate was concentrated to give the title compound as colorless crystals (yield 0.85 g, 67%).

S3. Refinement

The methyl H atoms were constrained to an ideal geometry, with C—H distances of 0.98 Å and U_iso(H) = 1.5U_eq(C), but each group was allowed to rotate freely along its C—C bond. The methylene H atoms were constrained with C—H distances of 0.99 Å and U_iso(H) = 1.2U_eq(C). The phenyl H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances in the range 0.95 Å and U_iso(H) = 1.2U_eq(C).

Figures

Fig. 1.

The molecular structure of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms have been omitted for clarity.

Crystal data

[Zn(C12H21N2Si)2]	F(000) = 2176
Mr = 508.19	Dx = 1.236 Mg m−3
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 9968 reflections
a = 29.7954 (12) Å	θ = 2.8–28.3°
b = 21.3566 (8) Å	µ = 1.01 mm−1
c = 8.5844 (3) Å	T = 200 K
V = 5462.5 (4) Å3	Block, colorless
Z = 8	0.20 × 0.15 × 0.15 mm

Data collection

Bruker SMART area-detector diffractometer	3296 independent reflections
Radiation source: fine-focus sealed tube	3153 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
φ and ω scan	θmax = 28.3°, θmin = 3.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −39→36
Tmin = 0.824, Tmax = 0.864	k = −28→28
12927 measured reflections	l = −11→11

Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.019	w = 1/[σ2(Fo2) + (0.0141P)2 + 1.7098P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.051	(Δ/σ)max < 0.001
S = 1.12	Δρmax = 0.23 e Å−3
3296 reflections	Δρmin = −0.23 e Å−3
147 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraint	Extinction coefficient: 0.00049 (6)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1484 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.028 (7)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Zn1	0.2500	0.2500	0.29180 (2)	0.02397 (7)
Si1	0.247147 (12)	0.121100 (17)	0.32504 (4)	0.02649 (10)
N2	0.28157 (4)	0.17456 (5)	0.43443 (15)	0.0259 (2)
N1	0.22836 (4)	0.17412 (5)	0.19372 (15)	0.0272 (2)
C1	0.20137 (5)	0.16863 (6)	0.06303 (15)	0.0270 (3)
C2	0.19263 (5)	0.11107 (7)	−0.01073 (18)	0.0342 (3)
H2	0.2063	0.0740	0.0281	0.041*
C3	0.16452 (6)	0.10739 (8)	−0.1389 (2)	0.0418 (4)
H3	0.1592	0.0679	−0.1863	0.050*
C6	0.18084 (5)	0.22167 (7)	−0.00242 (17)	0.0348 (3)
H6	0.1864	0.2616	0.0424	0.042*
C8	0.20082 (6)	0.08844 (8)	0.4469 (2)	0.0443 (4)
H8A	0.1845	0.1228	0.4971	0.066*
H8B	0.2134	0.0608	0.5268	0.066*
H8C	0.1802	0.0646	0.3807	0.066*
C9	0.32965 (5)	0.17499 (7)	0.38603 (19)	0.0329 (3)
H9A	0.3313	0.1681	0.2721	0.039*
H9B	0.3453	0.1397	0.4375	0.039*
C11	0.27592 (6)	0.17628 (8)	0.60640 (19)	0.0359 (3)
H11A	0.2434	0.1768	0.6303	0.043*
H11B	0.2888	0.2159	0.6458	0.043*
C7	0.28096 (6)	0.05379 (8)	0.2524 (3)	0.0530 (5)
H7A	0.2609	0.0192	0.2244	0.080*
H7B	0.3017	0.0400	0.3342	0.080*
H7C	0.2981	0.0667	0.1605	0.080*
C4	0.14411 (5)	0.15989 (9)	−0.19904 (19)	0.0432 (4)
H4	0.1245	0.1568	−0.2860	0.052*
C12	0.29757 (7)	0.12168 (10)	0.6950 (3)	0.0568 (5)
H12A	0.2863	0.0819	0.6535	0.085*
H12B	0.2900	0.1248	0.8059	0.085*
H12C	0.3302	0.1234	0.6824	0.085*
C10	0.35400 (5)	0.23565 (7)	0.4258 (2)	0.0401 (4)
H10A	0.3383	0.2710	0.3776	0.060*
H10B	0.3848	0.2337	0.3862	0.060*
H10C	0.3545	0.2412	0.5391	0.060*
C5	0.15272 (6)	0.21749 (8)	−0.12999 (19)	0.0402 (4)
H5	0.1392	0.2543	−0.1708	0.048*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Zn1	0.02833 (11)	0.01733 (9)	0.02623 (11)	−0.00051 (8)	0.000	0.000
Si1	0.0303 (2)	0.01746 (17)	0.0317 (3)	0.00078 (13)	−0.00043 (17)	0.00132 (13)
N2	0.0254 (6)	0.0237 (5)	0.0286 (6)	0.0029 (4)	−0.0020 (5)	0.0004 (5)
N1	0.0366 (7)	0.0197 (5)	0.0253 (5)	−0.0027 (5)	−0.0024 (5)	−0.0004 (5)
C1	0.0303 (7)	0.0291 (7)	0.0216 (7)	−0.0042 (5)	0.0044 (5)	−0.0004 (5)
C2	0.0417 (8)	0.0294 (7)	0.0316 (7)	−0.0058 (6)	0.0021 (6)	−0.0041 (6)
C3	0.0474 (10)	0.0449 (9)	0.0332 (8)	−0.0118 (7)	0.0002 (7)	−0.0115 (7)
C6	0.0453 (9)	0.0326 (7)	0.0264 (7)	0.0006 (6)	−0.0035 (6)	−0.0019 (6)
C8	0.0461 (10)	0.0440 (9)	0.0427 (9)	−0.0117 (7)	0.0022 (8)	0.0132 (8)
C9	0.0279 (7)	0.0294 (7)	0.0414 (8)	0.0040 (5)	0.0005 (6)	−0.0020 (6)
C11	0.0372 (8)	0.0418 (9)	0.0286 (7)	0.0022 (6)	−0.0030 (6)	0.0028 (6)
C7	0.0506 (10)	0.0278 (7)	0.0806 (15)	0.0098 (7)	−0.0018 (10)	−0.0167 (9)
C4	0.0396 (9)	0.0651 (11)	0.0250 (7)	−0.0074 (7)	−0.0038 (7)	−0.0055 (8)
C12	0.0654 (12)	0.0608 (12)	0.0442 (10)	0.0046 (9)	−0.0136 (10)	0.0175 (9)
C10	0.0296 (8)	0.0406 (8)	0.0502 (10)	−0.0015 (6)	−0.0034 (7)	−0.0047 (7)
C5	0.0442 (9)	0.0499 (10)	0.0267 (7)	0.0068 (7)	−0.0021 (6)	0.0027 (7)

Geometric parameters (Å, º)

Zn1—N1	1.9367 (11)	C8—H8B	0.9800
Zn1—N1i	1.9367 (11)	C8—H8C	0.9800
Zn1—N2i	2.2315 (12)	C9—C10	1.524 (2)
Zn1—N2	2.2315 (12)	C9—H9A	0.9900
Zn1—Si1i	2.7689 (4)	C9—H9B	0.9900
Si1—N1	1.6930 (13)	C11—C12	1.535 (2)
Si1—N2	1.7993 (12)	C11—H11A	0.9900
Si1—C7	1.8628 (16)	C11—H11B	0.9900
Si1—C8	1.8669 (17)	C7—H7A	0.9800
N2—C11	1.486 (2)	C7—H7B	0.9800
N2—C9	1.4917 (18)	C7—H7C	0.9800
N1—C1	1.3854 (18)	C4—C5	1.389 (2)
C1—C6	1.405 (2)	C4—H4	0.9500
C1—C2	1.4070 (19)	C12—H12A	0.9800
C2—C3	1.385 (2)	C12—H12B	0.9800
C2—H2	0.9500	C12—H12C	0.9800
C3—C4	1.376 (3)	C10—H10A	0.9800
C3—H3	0.9500	C10—H10B	0.9800
C6—C5	1.382 (2)	C10—H10C	0.9800
C6—H6	0.9500	C5—H5	0.9500
C8—H8A	0.9800
N1—Zn1—N1i	128.46 (8)	Si1—C8—H8C	109.5
N1—Zn1—N2i	134.62 (5)	H8A—C8—H8C	109.5
N1i—Zn1—N2i	76.98 (5)	H8B—C8—H8C	109.5
N1—Zn1—N2	76.98 (5)	N2—C9—C10	113.59 (12)
N1i—Zn1—N2	134.62 (5)	N2—C9—H9A	108.8
N2i—Zn1—N2	113.45 (6)	C10—C9—H9A	108.8
N1—Zn1—Si1i	152.49 (4)	N2—C9—H9B	108.8
N1i—Zn1—Si1i	37.12 (4)	C10—C9—H9B	108.8
N2i—Zn1—Si1i	40.41 (3)	H9A—C9—H9B	107.7
N2—Zn1—Si1i	130.41 (3)	N2—C11—C12	115.22 (15)
N1—Si1—N2	96.41 (6)	N2—C11—H11A	108.5
N1—Si1—C7	118.18 (9)	C12—C11—H11A	108.5
N2—Si1—C7	110.86 (7)	N2—C11—H11B	108.5
N1—Si1—C8	112.23 (8)	C12—C11—H11B	108.5
N2—Si1—C8	111.48 (7)	H11A—C11—H11B	107.5
C7—Si1—C8	107.39 (9)	Si1—C7—H7A	109.5
C11—N2—C9	112.67 (12)	Si1—C7—H7B	109.5
C11—N2—Si1	118.00 (11)	H7A—C7—H7B	109.5
C9—N2—Si1	113.95 (9)	Si1—C7—H7C	109.5
C11—N2—Zn1	118.64 (10)	H7A—C7—H7C	109.5
C9—N2—Zn1	104.34 (8)	H7B—C7—H7C	109.5
Si1—N2—Zn1	86.07 (5)	C3—C4—C5	118.69 (15)
C1—N1—Si1	132.42 (10)	C3—C4—H4	120.7
C1—N1—Zn1	128.03 (9)	C5—C4—H4	120.7
Si1—N1—Zn1	99.21 (6)	C11—C12—H12A	109.5
N1—C1—C6	120.57 (12)	C11—C12—H12B	109.5
N1—C1—C2	123.07 (13)	H12A—C12—H12B	109.5
C6—C1—C2	116.36 (13)	C11—C12—H12C	109.5
C3—C2—C1	121.27 (15)	H12A—C12—H12C	109.5
C3—C2—H2	119.4	H12B—C12—H12C	109.5
C1—C2—H2	119.4	C9—C10—H10A	109.5
C4—C3—C2	121.25 (15)	C9—C10—H10B	109.5
C4—C3—H3	119.4	H10A—C10—H10B	109.5
C2—C3—H3	119.4	C9—C10—H10C	109.5
C5—C6—C1	121.94 (15)	H10A—C10—H10C	109.5
C5—C6—H6	119.0	H10B—C10—H10C	109.5
C1—C6—H6	119.0	C6—C5—C4	120.48 (16)
Si1—C8—H8A	109.5	C6—C5—H5	119.8
Si1—C8—H8B	109.5	C4—C5—H5	119.8
H8A—C8—H8B	109.5
N1—Si1—N2—C11	129.24 (11)	N1i—Zn1—N1—C1	−40.18 (11)
C7—Si1—N2—C11	−107.31 (13)	N2i—Zn1—N1—C1	72.13 (15)
C8—Si1—N2—C11	12.27 (14)	N2—Zn1—N1—C1	−177.65 (13)
N1—Si1—N2—C9	−95.22 (10)	Si1i—Zn1—N1—C1	7.03 (19)
C7—Si1—N2—C9	28.23 (13)	N1i—Zn1—N1—Si1	145.83 (7)
C8—Si1—N2—C9	147.82 (10)	N2i—Zn1—N1—Si1	−101.86 (7)
N1—Si1—N2—Zn1	8.73 (6)	N2—Zn1—N1—Si1	8.36 (6)
C7—Si1—N2—Zn1	132.18 (8)	Si1i—Zn1—N1—Si1	−166.96 (3)
C8—Si1—N2—Zn1	−108.23 (7)	Si1—N1—C1—C6	162.62 (12)
N1—Zn1—N2—C11	−127.69 (11)	Zn1—N1—C1—C6	−9.3 (2)
N1i—Zn1—N2—C11	100.35 (13)	Si1—N1—C1—C2	−17.0 (2)
N2i—Zn1—N2—C11	5.59 (10)	Zn1—N1—C1—C2	171.08 (11)
Si1i—Zn1—N2—C11	49.47 (12)	N1—C1—C2—C3	178.36 (14)
N1—Zn1—N2—C9	105.95 (9)	C6—C1—C2—C3	−1.3 (2)
N1i—Zn1—N2—C9	−26.01 (12)	C1—C2—C3—C4	0.0 (2)
N2i—Zn1—N2—C9	−120.77 (9)	N1—C1—C6—C5	−178.12 (14)
Si1i—Zn1—N2—C9	−76.89 (9)	C2—C1—C6—C5	1.5 (2)
N1—Zn1—N2—Si1	−7.78 (5)	C11—N2—C9—C10	−66.02 (17)
N1i—Zn1—N2—Si1	−139.74 (6)	Si1—N2—C9—C10	156.06 (12)
N2i—Zn1—N2—Si1	125.50 (5)	Zn1—N2—C9—C10	63.99 (14)
Si1i—Zn1—N2—Si1	169.383 (19)	C9—N2—C11—C12	−59.38 (18)
N2—Si1—N1—C1	176.23 (13)	Si1—N2—C11—C12	76.70 (17)
C7—Si1—N1—C1	58.42 (16)	Zn1—N2—C11—C12	178.35 (12)
C8—Si1—N1—C1	−67.40 (16)	C2—C3—C4—C5	1.0 (2)
N2—Si1—N1—Zn1	−10.18 (7)	C1—C6—C5—C4	−0.5 (2)
C7—Si1—N1—Zn1	−127.99 (8)	C3—C4—C5—C6	−0.7 (2)
C8—Si1—N1—Zn1	106.18 (8)

Symmetry code: (i) −x+1/2, −y+1/2, z.