Dichloro(tetrahydrofuran-O)[(trimethylsilyl)amido-N]gallium(III)

The title compound, [GaCl₂(C₃H₁₀NSi)(C₄H₈O)], is the tetra­hydro­furan-coordinated monomer of the previously structurally characterized dimer [GaN(H)SiMe₃Cl₂]₂. The title compound consists of discrete monomeric mol­ecules with two crystallographically independent mol­ecules within the unit cell. The crystal structure is composed of a Ga atom in a four-coordinate tetrahedral arrangement, with Ga-N distances of 2.025 (3) and 2.026 (3) Å in the two independent mol­ecules.

S1. Comment

During the course of examining (II) (Wiberg & Schmid, 1966) as a potential synthon for the preparation of a novel zinc amide, it was mixed with a solution of Me₂Zn in toluene. However, the only compound to be isolated from the reaction, after crystallization from tetrahydrofuran (THF) and work-up, was the title compound, (I), which is the THF-coordinated monomer of the starting material, the previously structurally characterized dimer [GaN(H)SiMe₃Cl₂]₂, (II) (Nutt et al., 1985). \scheme

Compound (I) has two crystallographically independent molecules within the unit cell. The crystal structure consists of discrete monomers, with the molecular structure consisting of a Ga atom bonded to two Cl atoms, an O atom from the coordinated THF molecule, which shows some disorder, and the N atom of the amino group. The N atom is further bonded to an Si atom from the trimethylsilyl ligand and to an H atom.

The bond distances in (I) are comparable with those in the starting compound, (II), which is a dimer consisting of a four-membered (GaN)₂ ring with the trimethylsilyl ligands on adjacent N atoms trans to one another. The Ga—Cl and N—Si interatomic distances in (I) are Ga1—Cl1 2.2178 (10), Ga1—Cl2 2.2182 (9), Ga2—Cl3 2.2226 (9) and Ga2—Cl4 2.2218 (10) Å, and N1—Si1 1.791 (3) and N2—Si2 1.800 (2) Å (for the crystallographically independent molecules 1 and 2, respectively). The corresponding values in (II) are Ga—Cl 2.150 (2) and 2.136 (2) Å, and N—Si 1.805 (4) Å. The Ga—N interatomic distances in (I) are slightly longer than those found in (II): Ga1—N1 2.026 (3) and Ga2—N2 2.025 (2) Å in (I), and Ga—N 1.974 (4) and 1.964 (4) Å in (II), with this bond lengthening most likely occurring due to the electron-releasing effect of the coordinated THF molecule.

The Ga—O distances [Ga1—O1 2.048 (2) and Ga2—O2 2.041 (2) Å] are within the range found in the other two structually characterized gallium complexes possessing a coordinated THF molecule and a Ga—Cl interaction, [GaSi(SiMe₃)₃Cl₂(C₄H₈O)] [2.010 (3) Å; Linti et al., 1996] and PhClGaSi(SiMe₃)·THF [2.061 (3) Å]. The interatomic angles about the four-coordinate Ga atom deviate from those of an ideal tetrahedron, with the most acute being O1—Ga1—Cl1 102.87 (7) and O2—Ga2—Cl3 101.55 (7)° (molecules 1 and 2, respectively) and the most obtuse being Cl2—Ga1—Cl1 119.27 (4) and Cl4—Ga2—Cl3 119.23 (4)°.

S2. Experimental

A 2M toluene solution of Me₂Zn (1.1 ml, 2.186 mmol) was added dropwise to a vigorously stirred ether solution of (II) (1.00 g, 2.18 mmol) at 195 K. The resulting reaction mixture was warmed to room temperature and stirred for 18 h. The solvent volume was removed by vacuum pump and the remaining white residue extracted in THF. Filtration through Celite, reduction of the solvent volume followed by overlayering with pentane, afforded, after solvent diffusion over a period of days at 238 K, compound (I) as white colourless crystals. Crystals suitable for an X-ray structural determination were grown using solvent diffusion, by placing saturated THF solutions of (I) overlayered with pentane at 238 K for several days (yield 40%). Spectroscopic analysis: ¹H-NMR (3000 MHz, C₆D₆, δ, p.p.m.): 0.234 (s, SiMe₃), 1.214 (m, furan), 2.785 (2.785 s, NH), 3.626 (m, furan); ¹³C-NMR (500 MHz, C₆D₆, δ, p.p.m.): 5.593 (SiMe₃), 19.404 (furan), 63.964 (furan).

S3. Refinement

H-atom positions were calculated for the ordered C atoms and were refined as riding. H atoms on N were located from difference Fourier maps and their coordinates were fixed during refinement. All H-atom displacement parameters were refined isotropically. Both of the THF ligands exhibited disorder; atoms C6, C7 and C13 were split into two positions and refined with occupancies of 0.5. H atoms were not calculated on atoms C5, C6, C7, C12, C13 and C14 of the disordered THF ligands.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97.

Figures

Fig. 1. The ORTEP (Johnson, 1968) representation of (I), showing the disorder in the THF ligands. Displacement ellipsoids are at the 30% probability level and all H atoms have been omitted for clarity.

Dichloro(tetrahydrofuran-O)[(trimethylsilyl)amido-N]gallium(III)

Crystal data

[Ga(C3H10NSi)Cl2(C4H8O)]	Z = 4
Mr = 300.93	F(000) = 616
Triclinic, P1	Dx = 1.433 Mg m^−3
a = 9.4539 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 11.8134 (3) Å	Cell parameters from 7048 reflections
c = 12.8999 (3) Å	θ = 1.6–28.4°
α = 86.918 (1)°	µ = 2.41 mm^−1
β = 83.194 (1)°	T = 193 K
γ = 77.308 (1)°	Cube, colourless
V = 1395.02 (6) Å^3	0.44 × 0.29 × 0.24 mm

Data collection

Siemens SMART 1K CCD diffractometer	4826 reflections with I > 2σ(I)
ω scans	Rint = 0.024
Absorption correction: multi-scan (Blessing, 1995)	θmax = 28.4°
Tmin = 0.392, Tmax = 0.563	h = −12→12
12575 measured reflections	k = −15→15
6380 independent reflections	l = −16→16

Refinement

Refinement on F^2	w = 1/[σ^2(Fo^2) + (0.0514P)^2 + 0.8048P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.038	(Δ/σ)max = 0.001
wR(F^2) = 0.108	Δρmax = 0.96 e Å^−3
S = 1.03	Δρmin = −0.51 e Å^−3
6380 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997)
261 parameters	Extinction coefficient: 0.0004 (5)
H atoms treated by a mixture of independent and constrained refinement

Special details

Experimental. A crystal of the title compound was selected and mounted on a glass fibre while in a stream of cold argon gas and placed immediately on a Siemens SMART 1 K CCD diffractometer at 173 K under a stream of cold nitrogen gas. Graphite monochromated Mo—Kα radiation was used (λ Å). Reflections were collected with a frame width of 0.3° in ω scans and a counting time of 30 s per frame at a crystal-to-detector distance of 4.911 cm. The double-pass method of scanning was used to reduce any noise. The first 50 frames of data were recollected at the conclusion of data collection to monitor crystal decay.

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	Occ. (<1)
Ga1	0.45992 (4)	0.49750 (3)	0.71387 (3)	0.03747 (12)
Ga2	0.52816 (4)	−0.01645 (3)	0.79044 (3)	0.03677 (11)
Si1	0.78047 (10)	0.30826 (8)	0.68609 (7)	0.0385 (2)
Si2	0.20911 (9)	−0.09996 (7)	0.81756 (7)	0.03112 (19)
Cl1	0.29953 (11)	0.57772 (9)	0.60453 (7)	0.0598 (3)
Cl2	0.56211 (10)	0.61067 (7)	0.79950 (8)	0.0493 (2)
Cl3	0.68233 (10)	0.00461 (10)	0.90170 (7)	0.0569 (3)
Cl4	0.42694 (10)	0.13652 (7)	0.69627 (8)	0.0498 (2)
N1	0.6004 (3)	0.3582 (2)	0.6485 (2)	0.0329 (6)
H1	0.5538	0.3009	0.6567	0.057 (12)*
N2	0.3899 (3)	−0.1160 (2)	0.85525 (19)	0.0301 (5)
H2D	0.3749	−0.0999	0.9285	0.056 (11)*
O1	0.3356 (3)	0.4260 (2)	0.82922 (18)	0.0464 (6)
O2	0.6625 (2)	−0.1235 (2)	0.68397 (18)	0.0418 (6)
C1	0.8876 (4)	0.4154 (4)	0.6338 (3)	0.0568 (10)
H1A	0.8799	0.4280	0.5612	0.084 (9)*
H1B	0.9870	0.3870	0.6447	0.084 (9)*
H1C	0.8512	0.4865	0.6687	0.084 (9)*
C2	0.7672 (5)	0.2999 (4)	0.8301 (3)	0.0604 (12)
H2A	0.7320	0.3755	0.8568	0.081 (9)*
H2B	0.8609	0.2682	0.8516	0.081 (9)*
H2C	0.7020	0.2516	0.8561	0.081 (9)*
C3	0.8531 (4)	0.1619 (3)	0.6308 (3)	0.0520 (10)
H3A	0.8001	0.1085	0.6650	0.070 (8)*
H3B	0.9533	0.1371	0.6409	0.070 (8)*
H3C	0.8431	0.1655	0.5582	0.070 (8)*
C4	0.1924 (5)	0.4064 (5)	0.8195 (4)	0.0686 (13)
H4A	0.1971	0.3527	0.7663	0.122 (16)*
H4B	0.1281	0.4770	0.8026	0.122 (16)*
C5	0.1423 (7)	0.3598 (7)	0.9207 (5)	0.113 (2)
C6	0.2197 (11)	0.3844 (9)	0.9954 (8)	0.069 (2)*	0.50
C6A	0.2707 (12)	0.3141 (10)	0.9785 (9)	0.076 (3)*	0.50
C7	0.3583 (15)	0.4212 (10)	0.9417 (8)	0.056 (3)	0.50
C7A	0.3884 (15)	0.3614 (11)	0.9199 (9)	0.063 (3)	0.50
C8	0.2253 (4)	−0.1045 (3)	0.6735 (3)	0.0453 (8)
H8A	0.2717	−0.0448	0.6438	0.060 (7)*
H8B	0.1309	−0.0932	0.6511	0.060 (7)*
H8C	0.2817	−0.1778	0.6514	0.060 (7)*
C9	0.1333 (4)	−0.2227 (3)	0.8791 (3)	0.0503 (9)
H9A	0.1908	−0.2938	0.8528	0.082 (9)*
H9B	0.0358	−0.2145	0.8634	0.082 (9)*
H9C	0.1343	−0.2226	0.9526	0.082 (9)*
C10	0.1021 (4)	0.0417 (3)	0.8642 (3)	0.0464 (9)
H10A	0.1092	0.0468	0.9365	0.073 (8)*
H10B	0.0028	0.0490	0.8533	0.073 (8)*
H10C	0.1392	0.1023	0.8266	0.073 (8)*
C11	0.8071 (4)	−0.1896 (4)	0.7018 (3)	0.0526 (10)
H11A	0.8002	−0.2527	0.7496	0.082 (11)*
H11B	0.8614	−0.1417	0.7293	0.082 (11)*
C12	0.8773 (5)	−0.2324 (5)	0.5984 (4)	0.0845 (17)
C13	0.7802 (14)	−0.2017 (11)	0.5231 (10)	0.086 (3)*	0.50
C13A	0.7532 (9)	−0.2480 (7)	0.5394 (6)	0.0460 (17)*	0.50
C14	0.6326 (5)	−0.1422 (5)	0.5792 (3)	0.0789 (17)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ga1	0.0389 (2)	0.0380 (2)	0.0322 (2)	−0.00129 (15)	−0.00541 (15)	0.00218 (14)
Ga2	0.0318 (2)	0.0458 (2)	0.0345 (2)	−0.01039 (15)	−0.00483 (15)	−0.00531 (15)
Si1	0.0384 (5)	0.0412 (5)	0.0319 (5)	0.0042 (4)	−0.0101 (4)	−0.0034 (4)
Si2	0.0275 (4)	0.0387 (4)	0.0277 (4)	−0.0075 (3)	−0.0055 (3)	0.0008 (3)
Cl1	0.0551 (6)	0.0739 (7)	0.0370 (5)	0.0168 (5)	−0.0131 (4)	0.0077 (4)
Cl2	0.0507 (5)	0.0357 (4)	0.0613 (6)	−0.0053 (4)	−0.0091 (4)	−0.0100 (4)
Cl3	0.0415 (5)	0.0998 (8)	0.0378 (5)	−0.0281 (5)	−0.0064 (4)	−0.0182 (5)
Cl4	0.0514 (5)	0.0403 (4)	0.0618 (6)	−0.0154 (4)	−0.0168 (4)	0.0071 (4)
N1	0.0330 (14)	0.0314 (13)	0.0342 (14)	−0.0052 (11)	−0.0082 (11)	0.0010 (11)
N2	0.0255 (13)	0.0378 (13)	0.0269 (13)	−0.0052 (10)	−0.0051 (10)	−0.0016 (10)
O1	0.0388 (13)	0.0692 (17)	0.0343 (13)	−0.0189 (12)	−0.0061 (10)	0.0063 (11)
O2	0.0292 (12)	0.0599 (15)	0.0317 (12)	0.0018 (10)	−0.0029 (9)	−0.0077 (10)
C1	0.044 (2)	0.068 (3)	0.062 (3)	−0.0153 (19)	−0.0090 (19)	−0.008 (2)
C2	0.076 (3)	0.057 (2)	0.038 (2)	0.015 (2)	−0.021 (2)	−0.0023 (17)
C3	0.054 (2)	0.050 (2)	0.044 (2)	0.0080 (17)	−0.0017 (17)	−0.0079 (17)
C4	0.048 (2)	0.097 (4)	0.069 (3)	−0.032 (2)	−0.014 (2)	0.001 (3)
C5	0.090 (4)	0.180 (7)	0.083 (4)	−0.079 (5)	0.021 (3)	−0.003 (4)
C7	0.065 (7)	0.086 (8)	0.021 (4)	−0.029 (7)	0.001 (4)	0.007 (5)
C7A	0.067 (8)	0.097 (9)	0.035 (6)	−0.039 (7)	−0.014 (5)	0.024 (6)
C8	0.051 (2)	0.057 (2)	0.0338 (18)	−0.0191 (17)	−0.0117 (16)	−0.0022 (15)
C9	0.046 (2)	0.061 (2)	0.048 (2)	−0.0237 (18)	−0.0077 (17)	0.0124 (18)
C10	0.0335 (18)	0.054 (2)	0.046 (2)	0.0045 (15)	−0.0060 (15)	−0.0008 (16)
C11	0.0327 (19)	0.072 (3)	0.046 (2)	0.0054 (18)	−0.0074 (16)	−0.0024 (19)
C12	0.051 (3)	0.129 (5)	0.057 (3)	0.022 (3)	−0.003 (2)	−0.032 (3)
C14	0.053 (3)	0.132 (4)	0.034 (2)	0.029 (3)	−0.0143 (18)	−0.036 (2)

Geometric parameters (Å, º)

Ga1—N1	2.026 (3)	O1—C7	1.489 (12)
Ga1—O1	2.048 (2)	O2—C14	1.451 (4)
Ga1—Cl1	2.2178 (10)	O2—C11	1.456 (4)
Ga1—Cl2	2.2182 (9)	C4—C5	1.456 (7)
Ga2—N2	2.025 (2)	C5—C6	1.357 (11)
Ga2—O2	2.041 (2)	C5—C6A	1.485 (12)
Ga2—Cl4	2.2218 (10)	C6—C6A	0.887 (12)
Ga2—Cl3	2.2226 (9)	C6—C7	1.546 (16)
Si1—N1	1.791 (3)	C6—C7A	1.742 (16)
Si1—C1	1.842 (4)	C6A—C7A	1.467 (16)
Si1—C2	1.846 (4)	C6A—C7	1.679 (16)
Si1—C3	1.861 (4)	C7—C7A	0.758 (13)
Si2—N2	1.800 (2)	C11—C12	1.480 (6)
Si2—C10	1.846 (4)	C12—C13	1.395 (13)
Si2—C8	1.850 (3)	C12—C13A	1.521 (9)
Si2—C9	1.856 (4)	C13—C13A	0.667 (13)
O1—C7A	1.441 (12)	C13—C14	1.533 (13)
O1—C4	1.444 (4)	C13A—C14	1.559 (9)
N1—Ga1—O1	103.78 (10)	C4—C5—C6A	108.6 (6)
N1—Ga1—Cl1	110.14 (8)	C6A—C6—C5	79.9 (11)
O1—Ga1—Cl1	102.87 (7)	C6A—C6—C7	82.4 (11)
N1—Ga1—Cl2	114.85 (8)	C5—C6—C7	108.7 (8)
O1—Ga1—Cl2	103.65 (8)	C6A—C6—C7A	57.3 (10)
Cl1—Ga1—Cl2	119.27 (4)	C5—C6—C7A	96.7 (8)
N2—Ga2—O2	102.82 (10)	C7—C6—C7A	25.8 (5)
N2—Ga2—Cl4	115.13 (7)	C6—C6A—C7A	92.2 (12)
O2—Ga2—Cl4	104.55 (7)	C6—C6A—C5	64.1 (10)
N2—Ga2—Cl3	110.87 (8)	C7A—C6A—C5	104.3 (9)
O2—Ga2—Cl3	101.55 (7)	C6—C6A—C7	66.0 (11)
Cl4—Ga2—Cl3	119.23 (4)	C7A—C6A—C7	26.8 (6)
N1—Si1—C1	107.09 (16)	C5—C6A—C7	96.4 (8)
N1—Si1—C2	108.18 (17)	C7A—C7—O1	71.5 (15)
C1—Si1—C2	110.6 (2)	C7A—C7—C6	91.7 (18)
N1—Si1—C3	107.12 (16)	O1—C7—C6	102.5 (9)
C1—Si1—C3	112.86 (19)	C7A—C7—C6A	60.8 (16)
C2—Si1—C3	110.71 (18)	O1—C7—C6A	96.9 (8)
N2—Si2—C10	107.20 (15)	C6—C7—C6A	31.6 (5)
N2—Si2—C8	107.64 (14)	C7—C7A—O1	78.5 (17)
C10—Si2—C8	111.11 (17)	C7—C7A—C6A	92.4 (19)
N2—Si2—C9	107.52 (15)	O1—C7A—C6A	109.5 (10)
C10—Si2—C9	112.08 (18)	C7—C7A—C6	62.5 (17)
C8—Si2—C9	111.05 (18)	O1—C7A—C6	95.7 (8)
Si1—N1—Ga1	122.06 (14)	C6A—C7A—C6	30.6 (5)
Si2—N2—Ga2	122.10 (13)	O2—C11—C12	105.6 (3)
C7A—O1—C4	108.2 (6)	C13—C12—C11	110.6 (6)
C7A—O1—C7	29.9 (5)	C13—C12—C13A	26.0 (5)
C4—O1—C7	109.2 (6)	C11—C12—C13A	105.3 (4)
C7A—O1—Ga1	125.5 (5)	C13A—C13—C12	87.6 (16)
C4—O1—Ga1	124.6 (2)	C13A—C13—C14	79.8 (15)
C7—O1—Ga1	123.8 (5)	C12—C13—C14	107.4 (8)
C14—O2—C11	109.8 (3)	C13—C13A—C12	66.4 (14)
C14—O2—Ga2	126.1 (2)	C13—C13A—C14	75.4 (14)
C11—O2—Ga2	124.1 (2)	C12—C13A—C14	100.1 (5)
O1—C4—C5	106.0 (4)	O2—C14—C13	105.0 (6)
C6—C5—C4	110.2 (6)	O2—C14—C13A	105.4 (4)
C6—C5—C6A	36.0 (5)	C13—C14—C13A	24.9 (5)