μ-1,2-Bis(diphenyl­phosphino)ethane-κ²P:P-bis[trichloridogallium(III)]

The centrosymmetric mol­ecule of the title compound, [(GaCl₃)₂(C₂₆H₂₄P₂)] or [(GaCl₃)₂{μ-Ph₂P(CH₂)₂PPh₂}], consists of two pseudo-tetra­hedral Ga centres coordinated by three Cl atoms [Ga—Cl = 2.1608 (8)–2.1648 (8) Å] and bridged by the diphosphane ligand [Ga—P = 2.3854 (8) Å].

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C)= 0.004 Å
• R factor = 0.032
• wR factor = 0.073
• Data-to-parameter ratio = 21.3

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S1. Comment

Gallium nitride, phosphide, and arsenide are compound semi-conductors (III-V materials) of key importance in the electronics industries; for example GaN, GaP and GaAs are used extensively in LED applications and GaAs is also widely used in integrated circuits, displays and solar cells (O'Brien & Pickett, 2004; Grant, 1993). Gallium halide and gallium alkyl complexes of organo-phosphorus or -arsenic ligands are precursors for the manufacture of GaP and GaAs (O'Brien & Pickett, 2004) and in the course of such an investigation, we obtained the title complex by combination of anhydrous GaCl₃ and Ph₂P(CH₂)₂PPh₂ in Et₂O.

The presence of two coincident Ga—Cl vibrations in the IR and Raman spectra and the ⁷¹Ga NMR chemical shift of δ = 267 are consistent with the presence of pseudo-tetrahedral gallium centres (Cl₃P donor sets) (Cheng et al., 2007; Baker et al., 1997). Colourless crystals of the title compound were obtained from CH₂Cl₂/n-hexane, and the structure determination confirms the deduction from the spectroscopic data.

The molecule (Figure 1) has a centre of symmetry which places the GaCl₃ groups in an anti arrangement. Comparison with the structure of [(I₃Ga)₂{µ-Ph₂P(CH₂)₂PPh₂}] reported previously (Brown et al., 1997) shows a very similar conformation, although in this case not determined by symmetry. The d(Ga—P) in the present chloro-complex of 2.3854 (8) Å) is shorter than the d(Ga—P) in the corresponding iodo-complex (2.404 (9), 2.410 (9) Å) consistent with weaker Lewis acidity of GaI₃.

Similar trends in bond lengths are observed in the [GaX₃(PPh₃)] (X = Cl or I) complexes (Cheng et al., 2007; Baker et al., 1997).

Related literature

For related literature, see: Baker et al. (1997); Brown et al. (1997); Cheng et al. (2007); Grant (1993); O'Brien & Pickett (2004).

S2. Experimental

A solution of Ph₂P(CH₂)₂PPh₂ (0.156 g, 0.39 mmol) in anhydrous Et₂O (5 cm³) was added dropwise to a stirred solution of GaCl₃ (0.137 g, 0.78 mmol) in Et₂O (4 cm³). After stirring at room temperature for 15 h, the resultant white precipitate was filtered off, washed with Et₂O and dried in vacuo. Yield: 63%. Required for C₂₆H₂₄Cl₆Ga₂P₂: C, 41.6; H, 3.1. Found: C, 41.6; H, 3.3%. ¹H NMR (CDCl₃): δ = 7.71–7.44 (m, [20H], Ph), 2.92 (d, [4H], CH₂). ³¹P{¹H} NMR (CDCl₃): δ = -7.6 (relative to external 85% H₃PO₄). ⁷¹Ga NMR: δ = 267 (relative to [Ga(H₂O)₆]³⁺ in water). IR (Nujol): ν(Ga—Cl) = 390(s), 351(m) cm^-1; Raman: ν(Ga—Cl) = 389(m), 352(s) cm^-1.

Crystals were obtained by vapour diffusion of n-hexane into a CH₂Cl₂ solution of the complex.

S3. Refinement

H atoms were placed in calculated positions (C—H = 0.95 (aromatic), 0.99 Å (CH₂)) and refined as riding; U_iso(H) was set equal to 1.2U_eq(C).

Computing details

Data collection: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); cell refinement: COLLECT and DENZO; data reduction: COLLECT and DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. Molecular structure of [(GaCl3)2{Ph2P(CH2)2PPh2}], showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are omitted for clarity. Symmetry operation: (a) -x, 1 - y, -z.

µ-1,2-Bis(diphenylphosphino)ethane-bis[trichloridogallium(III)]

Crystal data

[(GaCl3)2(C26H24P2)]	Z = 1
Mr = 750.53	F(000) = 374
Triclinic, P1	Dx = 1.630 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.3586 (10) Å	Cell parameters from 3379 reflections
b = 9.457 (2) Å	θ = 2.9–27.5°
c = 11.644 (2) Å	µ = 2.41 mm^−1
α = 66.137 (8)°	T = 120 K
β = 77.057 (10)°	Plate, colourless
γ = 65.54 (1)°	0.20 × 0.20 × 0.04 mm
V = 764.4 (2) Å^3

Data collection

Nonius KappaCCD area-detector diffractometer	3469 independent reflections
Radiation source: Nonius rotating anode	2672 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
φ and ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −10→10
Tmin = 0.645, Tmax = 0.908	k = −12→12
15738 measured reflections	l = −15→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.073	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0287P)^2 + 0.6686P] where P = (Fo^2 + 2Fc^2)/3
3469 reflections	(Δ/σ)max < 0.001
163 parameters	Δρmax = 0.56 e Å^−3
0 restraints	Δρmin = −0.64 e Å^−3

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
Ga1	0.32216 (4)	0.20961 (3)	0.22313 (3)	0.01933 (9)
Cl1	0.35788 (9)	−0.00419 (9)	0.39476 (7)	0.03122 (18)
Cl2	0.48454 (9)	0.15689 (9)	0.06153 (7)	0.03109 (17)
Cl3	0.35063 (9)	0.41397 (9)	0.24547 (8)	0.03397 (18)
P1	0.02504 (8)	0.28638 (8)	0.18155 (6)	0.01615 (15)
C1	−0.1279 (3)	0.3960 (3)	0.2806 (2)	0.0173 (5)
C2	−0.0817 (3)	0.3569 (3)	0.4008 (2)	0.0221 (6)
H2	0.0249	0.2687	0.4314	0.026*
C3	−0.1914 (4)	0.4470 (3)	0.4752 (3)	0.0256 (6)
H3	−0.1605	0.4198	0.5573	0.031*
C4	−0.3461 (3)	0.5766 (3)	0.4307 (3)	0.0219 (6)
H4	−0.4199	0.6392	0.4818	0.026*
C5	−0.3935 (3)	0.6153 (3)	0.3124 (3)	0.0231 (6)
H5	−0.4998	0.7043	0.2822	0.028*
C6	−0.2857 (3)	0.5241 (3)	0.2372 (2)	0.0195 (6)
H6	−0.3195	0.5491	0.1565	0.023*
C7	−0.0119 (3)	0.1020 (3)	0.2033 (2)	0.0176 (5)
C8	0.1053 (4)	−0.0017 (3)	0.1387 (3)	0.0226 (6)
H8	0.1985	0.0274	0.0839	0.027*
C9	0.0850 (4)	−0.1466 (3)	0.1550 (3)	0.0258 (6)
H9	0.1638	−0.2170	0.1109	0.031*
C10	−0.0500 (4)	−0.1892 (3)	0.2357 (3)	0.0248 (6)
H10	−0.0640	−0.2887	0.2467	0.030*
C11	−0.1646 (3)	−0.0873 (3)	0.3003 (3)	0.0254 (6)
H11	−0.2563	−0.1178	0.3561	0.030*
C12	−0.1467 (3)	0.0590 (3)	0.2843 (3)	0.0211 (6)
H12	−0.2261	0.1291	0.3285	0.025*
C13	−0.0181 (3)	0.4203 (3)	0.0182 (2)	0.0174 (5)
H13A	0.0569	0.3586	−0.0378	0.021*
H13B	−0.1426	0.4498	0.0052	0.021*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ga1	0.02001 (16)	0.01879 (16)	0.02054 (17)	−0.00612 (12)	0.00056 (11)	−0.01015 (12)
Cl1	0.0287 (4)	0.0259 (4)	0.0247 (4)	−0.0010 (3)	−0.0019 (3)	−0.0043 (3)
Cl2	0.0270 (4)	0.0394 (4)	0.0267 (4)	−0.0085 (3)	0.0062 (3)	−0.0193 (3)
Cl3	0.0343 (4)	0.0321 (4)	0.0482 (5)	−0.0150 (3)	−0.0018 (3)	−0.0239 (4)
P1	0.0197 (3)	0.0142 (3)	0.0162 (3)	−0.0075 (3)	0.0014 (3)	−0.0069 (3)
C1	0.0207 (13)	0.0138 (12)	0.0190 (13)	−0.0077 (10)	0.0024 (10)	−0.0078 (10)
C2	0.0219 (14)	0.0201 (14)	0.0185 (14)	−0.0032 (11)	−0.0017 (11)	−0.0057 (11)
C3	0.0323 (16)	0.0272 (15)	0.0186 (14)	−0.0092 (12)	0.0008 (12)	−0.0122 (12)
C4	0.0221 (14)	0.0204 (14)	0.0255 (15)	−0.0093 (11)	0.0078 (11)	−0.0134 (12)
C5	0.0172 (13)	0.0197 (14)	0.0296 (16)	−0.0048 (11)	0.0013 (11)	−0.0096 (12)
C6	0.0204 (13)	0.0213 (14)	0.0183 (14)	−0.0094 (11)	−0.0022 (10)	−0.0060 (11)
C7	0.0203 (13)	0.0138 (12)	0.0174 (13)	−0.0061 (10)	−0.0048 (10)	−0.0025 (10)
C8	0.0264 (14)	0.0216 (14)	0.0219 (14)	−0.0125 (11)	0.0042 (11)	−0.0088 (12)
C9	0.0348 (16)	0.0199 (14)	0.0248 (15)	−0.0095 (12)	0.0005 (12)	−0.0117 (12)
C10	0.0310 (15)	0.0177 (14)	0.0283 (16)	−0.0120 (12)	−0.0078 (12)	−0.0043 (12)
C11	0.0214 (14)	0.0207 (14)	0.0329 (16)	−0.0116 (11)	0.0011 (12)	−0.0059 (12)
C12	0.0202 (13)	0.0154 (13)	0.0259 (15)	−0.0049 (10)	−0.0006 (11)	−0.0078 (11)
C13	0.0223 (13)	0.0185 (13)	0.0132 (13)	−0.0081 (11)	0.0004 (10)	−0.0073 (11)

Geometric parameters (Å, º)

Ga1—Cl1	2.1608 (8)	C5—H5	0.9500
Ga1—Cl2	2.1648 (8)	C6—H6	0.9500
Ga1—Cl3	2.1620 (8)	C7—C12	1.385 (4)
Ga1—P1	2.3854 (8)	C7—C8	1.399 (4)
P1—C1	1.802 (2)	C8—C9	1.383 (4)
P1—C7	1.804 (3)	C8—H8	0.9500
P1—C13	1.825 (3)	C9—C10	1.383 (4)
C1—C2	1.396 (4)	C9—H9	0.9500
C1—C6	1.394 (3)	C10—C11	1.383 (4)
C2—C3	1.382 (4)	C10—H10	0.9500
C2—H2	0.9500	C11—C12	1.386 (4)
C3—C4	1.385 (4)	C11—H11	0.9500
C3—H3	0.9500	C12—H12	0.9500
C4—C5	1.381 (4)	C13—C13^i	1.532 (5)
C4—H4	0.9500	C13—H13A	0.9900
C5—C6	1.391 (4)	C13—H13B	0.9900
Cl1—Ga1—Cl2	114.33 (3)	C5—C6—C1	119.8 (2)
Cl1—Ga1—Cl3	112.70 (3)	C5—C6—H6	120.1
Cl3—Ga1—Cl2	110.48 (3)	C1—C6—H6	120.1
Cl1—Ga1—P1	103.11 (3)	C12—C7—C8	120.2 (2)
Cl2—Ga1—P1	106.38 (3)	C12—C7—P1	122.0 (2)
Cl3—Ga1—P1	109.27 (3)	C8—C7—P1	117.67 (19)
C1—P1—C7	111.46 (12)	C9—C8—C7	119.7 (2)
C1—P1—C13	107.72 (12)	C9—C8—H8	120.1
C7—P1—C13	105.83 (11)	C7—C8—H8	120.1
C1—P1—Ga1	111.15 (9)	C8—C9—C10	120.0 (3)
C7—P1—Ga1	108.80 (8)	C8—C9—H9	120.0
C13—P1—Ga1	111.78 (9)	C10—C9—H9	120.0
C2—C1—C6	119.7 (2)	C11—C10—C9	120.2 (2)
C2—C1—P1	118.82 (19)	C11—C10—H10	119.9
C6—C1—P1	121.4 (2)	C9—C10—H10	119.9
C3—C2—C1	119.9 (2)	C10—C11—C12	120.6 (2)
C3—C2—H2	120.1	C10—C11—H11	119.7
C1—C2—H2	120.1	C12—C11—H11	119.7
C4—C3—C2	120.3 (3)	C7—C12—C11	119.3 (2)
C4—C3—H3	119.9	C7—C12—H12	120.3
C2—C3—H3	119.9	C11—C12—H12	120.3
C3—C4—C5	120.3 (2)	C13^i—C13—P1	112.4 (2)
C3—C4—H4	119.9	C13^i—C13—H13A	109.1
C5—C4—H4	119.9	P1—C13—H13A	109.1
C4—C5—C6	120.1 (2)	C13^i—C13—H13B	109.1
C4—C5—H5	120.0	P1—C13—H13B	109.1
C6—C5—H5	120.0	H13A—C13—H13B	107.8
Cl1—Ga1—P1—C1	77.84 (9)	C4—C5—C6—C1	−1.4 (4)
Cl3—Ga1—P1—C1	−42.24 (9)	C2—C1—C6—C5	1.9 (4)
Cl2—Ga1—P1—C1	−161.53 (9)	P1—C1—C6—C5	−174.51 (19)
Cl1—Ga1—P1—C7	−45.25 (9)	C1—P1—C7—C12	2.0 (3)
Cl3—Ga1—P1—C7	−165.34 (9)	C13—P1—C7—C12	−114.9 (2)
Cl2—Ga1—P1—C7	75.37 (9)	Ga1—P1—C7—C12	124.9 (2)
Cl1—Ga1—P1—C13	−161.76 (9)	C1—P1—C7—C8	−175.6 (2)
Cl3—Ga1—P1—C13	78.15 (9)	C13—P1—C7—C8	67.5 (2)
Cl2—Ga1—P1—C13	−41.14 (9)	Ga1—P1—C7—C8	−52.7 (2)
C7—P1—C1—C2	90.2 (2)	C12—C7—C8—C9	0.7 (4)
C13—P1—C1—C2	−154.1 (2)	P1—C7—C8—C9	178.3 (2)
Ga1—P1—C1—C2	−31.3 (2)	C7—C8—C9—C10	−0.5 (4)
C7—P1—C1—C6	−93.3 (2)	C8—C9—C10—C11	−0.1 (4)
C13—P1—C1—C6	22.3 (2)	C9—C10—C11—C12	0.6 (4)
Ga1—P1—C1—C6	145.10 (18)	C8—C7—C12—C11	−0.2 (4)
C6—C1—C2—C3	−0.9 (4)	P1—C7—C12—C11	−177.8 (2)
P1—C1—C2—C3	175.6 (2)	C10—C11—C12—C7	−0.4 (4)
C1—C2—C3—C4	−0.6 (4)	C1—P1—C13—C13^i	64.0 (3)
C2—C3—C4—C5	1.0 (4)	C7—P1—C13—C13^i	−176.6 (2)
C3—C4—C5—C6	−0.1 (4)	Ga1—P1—C13—C13^i	−58.4 (3)

Symmetry code: (i) −x, −y+1, −z.