Masking of Lewis acidity trends in the solid-state structures of tri­chlorido- and tri­bromido­(2,2′:6′,2′′-terpyridine-κ³N,N′,N′′)gallium(III)

The mol­ecular structures of tri­chlorido­(2,2′:6′,2′′-terpyridine-κ³N,N′,N′′)gallium(III), [GaCl₃(C₁₅H₁₁N₃)], and tri­bromido­(2,2′:6′,2′′-terpyridine-κ³N,N′,N′′)gallium(III), [GaBr₃(C₁₅H₁₁N₃)], are isostructural, with the Ga^III atom displaying an octa­hedral geometry. It is shown that the Ga—N distances in the two complexes are the same within experimental error, in contrast to expected bond lengthening in the bromide complex due to the lower Lewis acidity of GaBr₃. Thus, masking of the Lewis acidity trends in the solid state is observed not only for complexes of group 13 metal halides with monodentate ligands but for complexes with the polydentate 2,2′:6′,2′′-terpyridine donor as well.

S1. Introduction

The Ga—L distances in molecular complexes of the form [GaX₃(L)] are expected to lengthen with a decrease of the Lewis acidity of the gallium trihalide. However, recently, on the example of molecular complexes of group 13 metal trihalides with monodentate donor ligands, it has been shown that the solid state masks the Lewis acidity trends (Timoshkin et al., 2012). It is of inter­est to explore if the same situation is observed for molecular complexes of group 13 metals with polydentate ligands. Therefore, the molecular structures of gallium trichloride and tribromide complexes with the tridentate ligand 2,2':6',2''-terpyridine (terpy) have been established by X-ray structure analysis. [GaCl₃(terpy)], (I), has already been reported by Beran et al. (1970) [atomic coordinates not readily available; Cambridge Structural Database (CSD; Allen, 2002; Groom & Allen, 2014) refcode TPYGAC], followed by its Al, In, and Tl analogs by Beran et al. (1972), but no structural information is available for [GaBr₃(terpy)], (II). Ionic [GaI₂(Phterpy)]I (Phterpy is 4'-phenyl-2,2':6',2''-terpyridine) was produced by Baker et al. (2004) by reaction of gallium moniiodide (GaI) with Phterpy in toluene.

S2. Experimental

S2.1. Synthesis and crystallization

GaCl₃ and GaBr₃ were obtained by direct reaction between the elements. Purification of the metal halides and terpy (Alfa Aesar, 97%) was carried out by multiple resublimations in sealed whole-glass systems under vacuum. The synthesss of complexes (I) and (II) were performed in aceto­nitrile (MeCN) solutions in a dry box under nitro­gen. MeCN was dried over CaH₂ and distilled before use. For the preparation of (I), GaCl₃ (0.0120 g, 0.068 mmol) was dissolved in MeCN (1 ml) and a terpy solution (0.72 ml) in MeCN (0.022 g ml^-1) was added. For the preparation of (II), GaBr₃ (0.0252 g, 0.081 mmol) was dissolved in MeCN (1 ml) and a terpy solution (0.86 ml) in MeCN (0.022 g ml^-1) was added. In both cases, a white crystalline powder was observed after a few minutes. Solutions in sealed vessels were heated to 303–313 K and stored for three weeks for crystal growth.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were constrained to ride on the pivot atom, with C—H distances set at 0.95 Å and with U_iso(H) = 1.2U_eq(C).

S3. Results and discussion

The molecular structures of [GaCl₃(terpy)], (I), and [GaBr₃(terpy)], (II), are shown in Figs. 1 and 2, respectively. The complexes are isostructural and the Ga^III atom has an o­cta­hedral geometry (mer isomer). The structural data for (I) are in good agreement with the previous structural study by Beran et al. (1970). Complex (II) is only the second example of an o­cta­hedral gallium tribromide compex; the first example is fac-[GaBr₃(Me₃[9]aneN₃)] (Willey et al., 2011).

Determined at 123 K in the present work, the Ga—N bond lengths of (II) are slightly shorter or equal within experimental error to those of (I) (Table 2). This small Ga—N bond shortening on going from GaCl₃ to GaBr₃ is in contrast to the trend expected based on the gas-phase Lewis acidity of galluim halides (GaCl₃ > GaBr₃) (Timoshkin et al., 2012). It is of inter­est if a similar situation is observed for complexes of gallium halides with other ligands. A search of the CSD revealed ten other [GaX₃(L)] pairs of isostructural molecular complexes, for which data for X = Cl and X = Br are available. Table 2 lists the Ga—L and Ga—X distances in such complexes, and the difference (Δ) in Ga—L distances in bromide and chloride complexes. For complexes with a coordination number (CN) of 4 (tetra­hedral geometry at the Ga atom), the values of Δ are positive, but for four out of seven [GaX₃(L)] pairs, Δ is less than 3σ, suggesting that GaBr₃ and GaCl₃ have essentially equal acceptor ability. In contrast, for all three structurally characterized [GaX₃(L)] pairs with CN = 5 (trigonal bipyramidal geometry at Ga), the values of Δ are positive and significantly larger than 3σ, indicating weaker acceptor strength of GaBr₃ compared to GaCl₃. Inter­estingly, for [GaX₃(terpy)] (CN = 6, o­cta­hedral geometry), the value of Δ is negative, but small (for two out of three Ga—N bonds it is less than 3σ). Thus, despite the lower Lewis acidity of gaseous GaBr₃ compared to GaCl₃, the Ga—N bond lengths in the solid [GaX₃(terpy)] complexes are equal within experimental error.

Note, that for complexes with CN = 4, the Ga—X distances in [GaX₃(L)] agree within 0.065 Å [minimal and maximal values are 2.125 (1)–2.190 (3) Å for X = Cl and 2.280 (1)–2.342 (3) Å for X = Br]. An increase of the CN of gallium to 6 leads to significant Ga—X bond lengthening [up to 2.4118 (6) and 2.6053 (3) Å for X = Cl, Br, respectively]. Ga—N distances also increase (Table 2). This may be related to larger structural reorganization of GaX₃ upon formation of o­cta­hedral complexes.

We conclude, that observed earlier masking of Lewis acidity trends of group 13 metal halide complexes with monodentate ligands in the solid state (Timoshkin et al., 2012) also holds for complexes with the polydentate donor terpy as well. Thus, the Ga—N bond length in the solid state can not serve as reliable indicator of the Lewis acidity.

Related literature

For related literature, see: Allen (2002); Baker et al. (2004); Beran et al. (1970, 1972); Groom & Allen (2014); Timoshkin et al. (2012); Willey et al. (2011).

Computing details

For both compounds, data collection: CrysAlis PRO (Agilent, 2013); cell refinement: CrysAlis PRO (Agilent, 2013); data reduction: CrysAlis PRO (Agilent, 2013). Program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007) for GaCl3_Terpy; SHELXS97 (Sheldrick, 2008) for GaBr3_Terpy. For both compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures

	Fig. 1. The molecular structure of (I). Displacement ellispoids are drawn at the ??% probability level and H atpms are shown as small spheres of arbitrary radii. [added caption OK?]
	Fig. 2. The molecular structure of (II). Displacement ellispoids are drawn at the ??% probability level and H atpms are shown as small spheres of arbitrary radii. [added caption OK?]

(GaCl3_Terpy) Trichlorido(2,2':6',2''-terpyridine-κ³N,N',N'')gallium(III)

Crystal data

[GaCl3(C15H11N3)]	F(000) = 816
Mr = 409.34	Dx = 1.749 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.7107 Å
a = 8.2492 (2) Å	Cell parameters from 5153 reflections
b = 14.1770 (3) Å	θ = 3.4–32.0°
c = 13.7119 (3) Å	µ = 2.28 mm^−1
β = 104.217 (3)°	T = 123 K
V = 1554.47 (7) Å^3	Block, colourless
Z = 4	0.08 × 0.05 × 0.02 mm

Data collection

Agilent SuperNova (single source at offset, Eos) diffractometer	5130 independent reflections
Radiation source: SuperNova (Mo) X-ray Source	3289 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.051
Detector resolution: 15.9702 pixels mm^-1	θmax = 32.3°, θmin = 2.9°
ω scans	h = −12→12
Absorption correction: gaussian [CrysAlis PRO (Agilent, 2013), based on expression derived by Clark & Reid (1995)]	k = −20→20
Tmin = 0.887, Tmax = 0.971	l = −19→20
16866 measured reflections

Refinement

Refinement on F^2	Primary atom site location: iterative
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.033	H-atom parameters constrained
wR(F^2) = 0.052	w = 1/[σ^2(Fo^2) + (0.014P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.82	(Δ/σ)max = 0.001
5130 reflections	Δρmax = 0.49 e Å^−3
199 parameters	Δρmin = −0.38 e Å^−3
0 restraints

Special details

Experimental. Absorption correction: CrysAlisPro, Agilent Technologies, Version 1.171.37.12a (release 12-09-2013 CrysAlis171 .NET) (compiled Sep 12 2013,13:51:24) Numerical absorption correction based on gaussian integration over a multifaceted crystal model

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ga4	0.46977 (3)	0.37280 (2)	0.27962 (2)	0.01282 (6)
Cl6	0.21670 (6)	0.39451 (3)	0.14921 (3)	0.01560 (11)
Cl7	0.31811 (7)	0.34913 (4)	0.39335 (4)	0.02083 (12)
Cl10	0.72624 (7)	0.35088 (4)	0.39657 (4)	0.02105 (12)
N2	0.5867 (2)	0.39907 (11)	0.16742 (11)	0.0116 (4)
N7	0.5009 (2)	0.51969 (11)	0.28737 (12)	0.0134 (4)
C2	0.7053 (3)	0.34255 (14)	0.03839 (14)	0.0173 (5)
H2	0.7329	0.2917	0.0003	0.021*
N6	0.4937 (2)	0.23730 (11)	0.22244 (12)	0.0133 (4)
C11	0.7053 (3)	0.50916 (14)	0.07511 (15)	0.0167 (5)
H11	0.7320	0.5723	0.0619	0.020*
C13	0.7480 (3)	0.43441 (15)	0.02065 (15)	0.0196 (5)
H13	0.8073	0.4465	−0.0293	0.024*
C16	0.6224 (2)	0.48881 (13)	0.14929 (14)	0.0125 (4)
C24	0.4591 (3)	0.67375 (14)	0.34695 (15)	0.0188 (5)
H24	0.4250	0.7126	0.3947	0.023*
C31	0.6212 (3)	0.32659 (14)	0.11308 (14)	0.0141 (4)
C33	0.5343 (3)	0.06642 (14)	0.13379 (16)	0.0188 (5)
H33	0.5465	0.0078	0.1028	0.023*
C37	0.4527 (3)	0.57620 (14)	0.35363 (15)	0.0165 (5)
H37	0.4132	0.5486	0.4066	0.020*
C39	0.5844 (3)	0.14945 (14)	0.09638 (14)	0.0165 (4)
H39	0.6314	0.1484	0.0397	0.020*
C41	0.5722 (3)	0.65554 (14)	0.20319 (15)	0.0169 (5)
H41	0.6146	0.6820	0.1508	0.020*
C43	0.5654 (2)	0.55866 (13)	0.21480 (14)	0.0135 (4)
C51	0.5158 (3)	0.71315 (14)	0.26983 (16)	0.0195 (5)
H51	0.5164	0.7797	0.2622	0.023*
C53	0.5648 (3)	0.23415 (14)	0.14312 (14)	0.0133 (4)
C56	0.4471 (3)	0.15650 (14)	0.25857 (14)	0.0163 (5)
H56	0.3992	0.1589	0.3148	0.020*
C63	0.4665 (3)	0.06947 (14)	0.21647 (16)	0.0193 (5)
H63	0.4339	0.0131	0.2439	0.023*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ga4	0.01588 (13)	0.01138 (11)	0.01229 (10)	−0.00043 (10)	0.00554 (9)	0.00044 (9)
Cl6	0.0156 (3)	0.0155 (3)	0.0159 (2)	−0.0005 (2)	0.0042 (2)	0.00170 (19)
Cl7	0.0263 (3)	0.0232 (3)	0.0164 (2)	−0.0028 (2)	0.0116 (2)	0.0015 (2)
Cl10	0.0203 (3)	0.0203 (3)	0.0194 (3)	0.0012 (2)	−0.0012 (2)	0.0006 (2)
N2	0.0106 (9)	0.0138 (9)	0.0104 (8)	0.0014 (7)	0.0025 (7)	0.0024 (6)
N7	0.0139 (10)	0.0115 (9)	0.0149 (8)	−0.0003 (7)	0.0040 (7)	−0.0014 (7)
C2	0.0204 (12)	0.0183 (11)	0.0142 (10)	0.0039 (9)	0.0064 (9)	−0.0003 (8)
N6	0.0143 (10)	0.0120 (9)	0.0132 (8)	0.0015 (7)	0.0027 (7)	0.0012 (7)
C11	0.0175 (12)	0.0130 (11)	0.0196 (11)	−0.0049 (9)	0.0047 (9)	0.0036 (8)
C13	0.0187 (13)	0.0257 (12)	0.0171 (11)	0.0004 (10)	0.0096 (9)	0.0053 (9)
C16	0.0128 (11)	0.0116 (10)	0.0125 (10)	0.0004 (8)	0.0020 (8)	0.0015 (7)
C24	0.0173 (12)	0.0179 (11)	0.0189 (11)	0.0032 (9)	0.0000 (9)	−0.0053 (8)
C31	0.0147 (11)	0.0135 (10)	0.0128 (10)	0.0001 (9)	0.0010 (8)	0.0004 (7)
C33	0.0176 (12)	0.0126 (11)	0.0244 (12)	0.0032 (9)	0.0018 (9)	−0.0044 (8)
C37	0.0169 (12)	0.0165 (11)	0.0160 (10)	0.0009 (9)	0.0038 (9)	−0.0009 (8)
C39	0.0159 (11)	0.0172 (11)	0.0165 (10)	0.0009 (9)	0.0042 (8)	−0.0018 (8)
C41	0.0161 (12)	0.0149 (11)	0.0175 (10)	−0.0041 (9)	0.0001 (9)	0.0023 (8)
C43	0.0123 (12)	0.0132 (10)	0.0141 (10)	0.0000 (8)	0.0013 (9)	−0.0004 (8)
C51	0.0172 (12)	0.0104 (11)	0.0260 (12)	−0.0006 (9)	−0.0040 (10)	0.0003 (8)
C53	0.0128 (11)	0.0144 (10)	0.0120 (10)	0.0007 (9)	0.0016 (8)	0.0008 (8)
C56	0.0145 (12)	0.0173 (11)	0.0183 (11)	0.0006 (9)	0.0061 (9)	0.0043 (8)
C63	0.0184 (12)	0.0126 (11)	0.0256 (12)	−0.0029 (9)	0.0030 (10)	0.0037 (8)

Geometric parameters (Å, º)

Ga4—Cl6	2.4118 (6)	C16—C43	1.489 (3)
Ga4—Cl7	2.2511 (5)	C24—H24	0.9500
Ga4—Cl10	2.3405 (6)	C24—C37	1.388 (3)
Ga4—N2	2.0412 (15)	C24—C51	1.375 (3)
Ga4—N7	2.0976 (15)	C31—C53	1.482 (3)
Ga4—N6	2.1024 (15)	C33—H33	0.9500
N2—C16	1.343 (2)	C33—C39	1.387 (3)
N2—C31	1.340 (2)	C33—C63	1.383 (3)
N7—C37	1.342 (2)	C37—H37	0.9500
N7—C43	1.356 (2)	C39—H39	0.9500
C2—H2	0.9500	C39—C53	1.389 (3)
C2—C13	1.386 (3)	C41—H41	0.9500
C2—C31	1.389 (3)	C41—C43	1.385 (3)
N6—C53	1.357 (2)	C41—C51	1.388 (3)
N6—C56	1.341 (2)	C51—H51	0.9500
C11—H11	0.9500	C56—H56	0.9500
C11—C13	1.391 (3)	C56—C63	1.388 (3)
C11—C16	1.388 (3)	C63—H63	0.9500
C13—H13	0.9500
Cl7—Ga4—Cl6	90.32 (2)	C11—C16—C43	126.11 (17)
Cl7—Ga4—Cl10	93.91 (2)	C37—C24—H24	120.6
Cl10—Ga4—Cl6	175.66 (2)	C51—C24—H24	120.6
N2—Ga4—Cl6	84.33 (5)	C51—C24—C37	118.8 (2)
N2—Ga4—Cl7	174.49 (5)	N2—C31—C2	119.83 (18)
N2—Ga4—Cl10	91.46 (5)	N2—C31—C53	113.55 (17)
N2—Ga4—N7	77.44 (6)	C2—C31—C53	126.60 (18)
N2—Ga4—N6	77.32 (6)	C39—C33—H33	120.2
N7—Ga4—Cl6	89.06 (5)	C63—C33—H33	120.2
N7—Ga4—Cl7	101.23 (5)	C63—C33—C39	119.60 (19)
N7—Ga4—Cl10	91.06 (5)	N7—C37—C24	121.8 (2)
N7—Ga4—N6	154.75 (6)	N7—C37—H37	119.1
N6—Ga4—Cl6	89.06 (5)	C24—C37—H37	119.1
N6—Ga4—Cl7	103.96 (5)	C33—C39—H39	120.5
N6—Ga4—Cl10	88.99 (5)	C33—C39—C53	118.95 (19)
C16—N2—Ga4	118.55 (13)	C53—C39—H39	120.5
C31—N2—Ga4	118.90 (13)	C43—C41—H41	120.7
C31—N2—C16	122.52 (17)	C43—C41—C51	118.54 (19)
C37—N7—Ga4	125.03 (14)	C51—C41—H41	120.7
C37—N7—C43	119.22 (17)	N7—C43—C16	114.26 (17)
C43—N7—Ga4	115.62 (12)	N7—C43—C41	121.52 (18)
C13—C2—H2	120.8	C41—C43—C16	124.21 (18)
C13—C2—C31	118.48 (18)	C24—C51—C41	119.96 (19)
C31—C2—H2	120.8	C24—C51—H51	120.0
C53—N6—Ga4	115.31 (12)	C41—C51—H51	120.0
C56—N6—Ga4	125.52 (13)	N6—C53—C31	114.86 (16)
C56—N6—C53	119.16 (16)	N6—C53—C39	121.35 (18)
C13—C11—H11	121.0	C39—C53—C31	123.79 (18)
C16—C11—H11	121.0	N6—C56—H56	118.9
C16—C11—C13	118.07 (18)	N6—C56—C63	122.19 (18)
C2—C13—C11	120.84 (19)	C63—C56—H56	118.9
C2—C13—H13	119.6	C33—C63—C56	118.69 (19)
C11—C13—H13	119.6	C33—C63—H63	120.7
N2—C16—C11	120.15 (17)	C56—C63—H63	120.7
N2—C16—C43	113.74 (17)
Ga4—N2—C16—C11	178.53 (15)	C13—C11—C16—C43	−179.55 (19)
Ga4—N2—C16—C43	−1.4 (2)	C16—N2—C31—C2	3.7 (3)
Ga4—N2—C31—C2	−178.05 (15)	C16—N2—C31—C53	−177.53 (17)
Ga4—N2—C31—C53	0.7 (2)	C16—C11—C13—C2	1.6 (3)
Ga4—N7—C37—C24	−172.22 (16)	C31—N2—C16—C11	−3.2 (3)
Ga4—N7—C43—C16	−7.1 (2)	C31—N2—C16—C43	176.86 (18)
Ga4—N7—C43—C41	171.51 (15)	C31—C2—C13—C11	−1.1 (3)
Ga4—N6—C53—C31	2.8 (2)	C33—C39—C53—N6	−1.9 (3)
Ga4—N6—C53—C39	−178.36 (15)	C33—C39—C53—C31	176.89 (19)
Ga4—N6—C56—C63	179.81 (16)	C37—N7—C43—C16	176.94 (18)
N2—C16—C43—N7	5.6 (3)	C37—N7—C43—C41	−4.5 (3)
N2—C16—C43—C41	−172.96 (19)	C37—C24—C51—C41	−2.8 (3)
N2—C31—C53—N6	−2.3 (3)	C39—C33—C63—C56	1.4 (3)
N2—C31—C53—C39	178.85 (19)	C43—N7—C37—C24	3.3 (3)
C2—C31—C53—N6	176.38 (19)	C43—C41—C51—C24	1.8 (3)
C2—C31—C53—C39	−2.5 (3)	C51—C24—C37—N7	0.3 (3)
N6—C56—C63—C33	−0.8 (3)	C51—C41—C43—N7	1.9 (3)
C11—C16—C43—N7	−174.34 (19)	C51—C41—C43—C16	−179.63 (19)
C11—C16—C43—C41	7.1 (3)	C53—N6—C56—C63	−1.1 (3)
C13—C2—C31—N2	−1.5 (3)	C56—N6—C53—C31	−176.39 (17)
C13—C2—C31—C53	179.90 (19)	C56—N6—C53—C39	2.5 (3)
C13—C11—C16—N2	0.5 (3)	C63—C33—C39—C53	−0.1 (3)

(GaBr3_Terpy) Tribromido(2,2':6',2''-terpyridine-κ³N,N',N'')gallium(III)

Crystal data

[GaBr3(C15H11N3)]	F(000) = 1032
Mr = 542.72	Dx = 2.199 Mg m^−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.5418 Å
a = 8.3602 (1) Å	Cell parameters from 16135 reflections
b = 14.5133 (1) Å	θ = 3.0–73.5°
c = 13.9874 (1) Å	µ = 10.85 mm^−1
β = 104.967 (1)°	T = 123 K
V = 1639.57 (3) Å^3	Block, colourless
Z = 4	0.12 × 0.1 × 0.08 mm

Data collection

Oxford Diffraction (Gemini Ultra, Ruby CCD) diffractometer	3288 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	3116 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.025
Detector resolution: 10.3546 pixels mm^-1	θmax = 73.7°, θmin = 4.5°
ω scans	h = −10→10
Absorption correction: multi-scan [CrysAlis PRO (Agilent, 2013), based on expression derived by Clark & Reid (1995)]	k = −17→17
Tmin = 0.676, Tmax = 1.000	l = −16→17
26629 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.020	H-atom parameters constrained
wR(F^2) = 0.050	w = 1/[σ^2(Fo^2) + (0.0251P)^2 + 1.7521P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
3288 reflections	Δρmax = 0.40 e Å^−3
200 parameters	Δρmin = −0.46 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00013 (2)

Special details

Experimental. Absorption correction: CrysAlisPro, Agilent Technologies, Version 1.171.35.19 (release 27-10-2011 CrysAlis171 .NET) (compiled Oct 27 2011,15:02:11) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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
Br2	0.80495 (3)	0.354146 (17)	0.395354 (17)	0.02511 (7)
Br1	0.69999 (3)	0.394094 (15)	0.136959 (16)	0.01881 (7)
Br3	1.23890 (3)	0.353584 (17)	0.404362 (18)	0.02517 (7)
Ga1	0.96843 (3)	0.374351 (18)	0.279622 (19)	0.01611 (7)
N2	1.0824 (2)	0.39713 (12)	0.17033 (13)	0.0159 (3)
N1	0.9980 (2)	0.51773 (13)	0.28395 (13)	0.0177 (4)
C1	0.9517 (3)	0.57427 (16)	0.34759 (17)	0.0215 (5)
H1	0.9120	0.5492	0.3982	0.026*
C3	1.0198 (3)	0.70639 (16)	0.26437 (18)	0.0245 (5)
H3	1.0233	0.7699	0.2565	0.029*
N3	0.9913 (2)	0.24078 (12)	0.22764 (13)	0.0175 (4)
C8	1.2414 (3)	0.42717 (18)	0.02660 (18)	0.0248 (5)
H8	1.2987	0.4372	−0.0212	0.030*
C10	1.1167 (3)	0.32507 (16)	0.11965 (15)	0.0178 (4)
C9	1.1985 (3)	0.33815 (17)	0.04597 (17)	0.0227 (5)
H9	1.2239	0.2884	0.0105	0.027*
C15	0.9456 (3)	0.16323 (16)	0.26449 (18)	0.0222 (5)
H15	0.8991	0.1670	0.3180	0.027*
C13	1.0322 (3)	0.07185 (16)	0.14554 (19)	0.0251 (5)
H13	1.0438	0.0151	0.1173	0.030*
C11	1.0616 (3)	0.23553 (15)	0.15049 (15)	0.0172 (4)
C2	0.9612 (3)	0.66899 (17)	0.34001 (18)	0.0253 (5)
H2	0.9288	0.7071	0.3851	0.030*
C6	1.1185 (3)	0.48393 (15)	0.15066 (16)	0.0181 (4)
C12	1.0820 (3)	0.15206 (16)	0.10751 (17)	0.0217 (5)
H12	1.1284	0.1497	0.0539	0.026*
C5	1.0630 (3)	0.55331 (15)	0.21266 (16)	0.0183 (4)
C7	1.1997 (3)	0.50141 (17)	0.07780 (17)	0.0222 (5)
H7	1.2255	0.5613	0.0636	0.027*
C4	1.0735 (3)	0.64761 (16)	0.20040 (18)	0.0218 (5)
H4	1.1158	0.6713	0.1502	0.026*
C14	0.9650 (3)	0.07734 (16)	0.22586 (19)	0.0253 (5)
H14	0.9334	0.0243	0.2535	0.030*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br2	0.03170 (14)	0.02706 (14)	0.02054 (12)	−0.00303 (10)	0.01394 (10)	0.00185 (9)
Br1	0.01962 (11)	0.01690 (12)	0.01982 (12)	−0.00044 (8)	0.00495 (8)	0.00211 (8)
Br3	0.02458 (13)	0.02321 (14)	0.02376 (13)	0.00013 (9)	−0.00088 (10)	0.00125 (9)
Ga1	0.02027 (14)	0.01329 (13)	0.01629 (13)	−0.00066 (10)	0.00748 (11)	0.00071 (10)
N2	0.0148 (8)	0.0160 (9)	0.0159 (8)	−0.0010 (7)	0.0024 (7)	0.0009 (7)
N1	0.0189 (8)	0.0156 (9)	0.0176 (9)	−0.0012 (7)	0.0030 (7)	−0.0003 (7)
C1	0.0210 (10)	0.0194 (11)	0.0229 (11)	0.0019 (9)	0.0036 (9)	−0.0030 (9)
C3	0.0232 (11)	0.0134 (11)	0.0310 (12)	0.0016 (9)	−0.0036 (9)	0.0001 (9)
N3	0.0184 (8)	0.0150 (9)	0.0186 (9)	0.0002 (7)	0.0037 (7)	0.0001 (7)
C8	0.0250 (11)	0.0289 (13)	0.0232 (11)	0.0007 (9)	0.0108 (9)	0.0051 (10)
C10	0.0170 (9)	0.0197 (11)	0.0156 (10)	0.0008 (8)	0.0026 (8)	−0.0001 (8)
C9	0.0269 (11)	0.0226 (12)	0.0201 (11)	0.0039 (9)	0.0090 (9)	0.0002 (9)
C15	0.0206 (10)	0.0195 (11)	0.0267 (12)	−0.0004 (9)	0.0063 (9)	0.0038 (9)
C13	0.0228 (11)	0.0159 (11)	0.0336 (13)	0.0010 (9)	0.0015 (10)	−0.0060 (9)
C11	0.0161 (9)	0.0173 (11)	0.0165 (10)	0.0007 (8)	0.0010 (8)	−0.0010 (8)
C2	0.0216 (11)	0.0216 (12)	0.0290 (12)	0.0032 (9)	−0.0003 (9)	−0.0061 (10)
C6	0.0182 (10)	0.0167 (11)	0.0170 (10)	−0.0009 (8)	0.0005 (8)	0.0033 (8)
C12	0.0203 (10)	0.0216 (12)	0.0222 (11)	0.0027 (9)	0.0034 (9)	−0.0028 (9)
C5	0.0172 (9)	0.0174 (11)	0.0178 (10)	−0.0022 (8)	0.0000 (8)	0.0008 (8)
C7	0.0218 (10)	0.0215 (12)	0.0229 (11)	−0.0033 (9)	0.0051 (9)	0.0064 (9)
C4	0.0189 (10)	0.0183 (11)	0.0246 (11)	−0.0024 (8)	−0.0006 (9)	0.0027 (9)
C14	0.0206 (11)	0.0171 (11)	0.0361 (13)	−0.0015 (9)	0.0034 (10)	0.0053 (10)

Geometric parameters (Å, º)

Br2—Ga1	2.3911 (3)	C8—C7	1.387 (3)
Br1—Ga1	2.6053 (3)	C10—C9	1.389 (3)
Br3—Ga1	2.4920 (3)	C10—C11	1.480 (3)
Ga1—N2	2.0265 (18)	C9—H9	0.9300
Ga1—N1	2.0946 (18)	C15—H15	0.9300
Ga1—N3	2.0965 (18)	C15—C14	1.385 (3)
N2—C10	1.336 (3)	C13—H13	0.9300
N2—C6	1.340 (3)	C13—C12	1.388 (3)
N1—C1	1.339 (3)	C13—C14	1.382 (4)
N1—C5	1.355 (3)	C11—C12	1.382 (3)
C1—H1	0.9300	C2—H2	0.9300
C1—C2	1.383 (3)	C6—C5	1.480 (3)
C3—H3	0.9300	C6—C7	1.386 (3)
C3—C2	1.386 (4)	C12—H12	0.9300
C3—C4	1.392 (3)	C5—C4	1.385 (3)
N3—C15	1.334 (3)	C7—H7	0.9300
N3—C11	1.358 (3)	C4—H4	0.9300
C8—H8	0.9300	C14—H14	0.9300
C8—C9	1.386 (3)
Br2—Ga1—Br1	90.120 (11)	C9—C10—C11	125.9 (2)
Br2—Ga1—Br3	94.881 (12)	C8—C9—C10	118.3 (2)
Br3—Ga1—Br1	174.836 (13)	C8—C9—H9	120.9
N2—Ga1—Br2	173.25 (5)	C10—C9—H9	120.9
N2—Ga1—Br1	83.35 (5)	N3—C15—H15	118.8
N2—Ga1—Br3	91.69 (5)	N3—C15—C14	122.3 (2)
N2—Ga1—N1	77.56 (7)	C14—C15—H15	118.8
N2—Ga1—N3	77.66 (7)	C12—C13—H13	120.4
N1—Ga1—Br2	100.73 (5)	C14—C13—H13	120.4
N1—Ga1—Br1	89.13 (5)	C14—C13—C12	119.2 (2)
N1—Ga1—Br3	91.20 (5)	N3—C11—C10	114.44 (19)
N1—Ga1—N3	155.22 (7)	N3—C11—C12	121.5 (2)
N3—Ga1—Br2	103.93 (5)	C12—C11—C10	124.1 (2)
N3—Ga1—Br1	88.50 (5)	C1—C2—C3	119.1 (2)
N3—Ga1—Br3	89.05 (5)	C1—C2—H2	120.4
C10—N2—Ga1	118.69 (15)	C3—C2—H2	120.4
C10—N2—C6	122.44 (19)	N2—C6—C5	113.46 (19)
C6—N2—Ga1	118.86 (15)	N2—C6—C7	120.1 (2)
C1—N1—Ga1	125.13 (15)	C7—C6—C5	126.4 (2)
C1—N1—C5	119.69 (19)	C13—C12—H12	120.5
C5—N1—Ga1	115.11 (14)	C11—C12—C13	119.0 (2)
N1—C1—H1	119.1	C11—C12—H12	120.5
N1—C1—C2	121.7 (2)	N1—C5—C6	114.70 (19)
C2—C1—H1	119.1	N1—C5—C4	121.2 (2)
C2—C3—H3	120.4	C4—C5—C6	124.1 (2)
C2—C3—C4	119.1 (2)	C8—C7—H7	120.9
C4—C3—H3	120.4	C6—C7—C8	118.3 (2)
C15—N3—Ga1	125.81 (15)	C6—C7—H7	120.9
C15—N3—C11	119.06 (19)	C3—C4—H4	120.5
C11—N3—Ga1	115.13 (14)	C5—C4—C3	119.0 (2)
C9—C8—H8	119.6	C5—C4—H4	120.5
C9—C8—C7	120.7 (2)	C15—C14—H14	120.6
C7—C8—H8	119.6	C13—C14—C15	118.8 (2)
N2—C10—C9	120.1 (2)	C13—C14—H14	120.6
N2—C10—C11	114.02 (18)
Br2—Ga1—N1—C1	7.81 (18)	N1—Ga1—N2—C10	179.70 (16)
Br2—Ga1—N1—C5	−169.17 (14)	N1—Ga1—N2—C6	−1.22 (15)
Br2—Ga1—N3—C15	−9.34 (19)	N1—Ga1—N3—C15	176.25 (17)
Br2—Ga1—N3—C11	171.66 (13)	N1—Ga1—N3—C11	−2.8 (3)
Br1—Ga1—N2—C10	−89.72 (15)	N1—C1—C2—C3	0.2 (3)
Br1—Ga1—N2—C6	89.36 (15)	N1—C5—C4—C3	1.6 (3)
Br1—Ga1—N1—C1	97.77 (17)	C1—N1—C5—C6	176.59 (18)
Br1—Ga1—N1—C5	−79.21 (15)	C1—N1—C5—C4	−3.9 (3)
Br1—Ga1—N3—C15	−99.09 (18)	N3—Ga1—N2—C10	0.19 (15)
Br1—Ga1—N3—C11	81.90 (14)	N3—Ga1—N2—C6	179.27 (17)
Br3—Ga1—N2—C10	88.85 (15)	N3—Ga1—N1—C1	−177.71 (17)
Br3—Ga1—N2—C6	−92.07 (15)	N3—Ga1—N1—C5	5.3 (3)
Br3—Ga1—N1—C1	−87.39 (17)	N3—C15—C14—C13	−0.8 (3)
Br3—Ga1—N1—C5	95.63 (15)	N3—C11—C12—C13	−1.2 (3)
Br3—Ga1—N3—C15	85.45 (18)	C10—N2—C6—C5	177.39 (18)
Br3—Ga1—N3—C11	−93.55 (14)	C10—N2—C6—C7	−2.4 (3)
Ga1—N2—C10—C9	−178.38 (16)	C10—C11—C12—C13	177.1 (2)
Ga1—N2—C10—C11	1.1 (2)	C9—C8—C7—C6	1.9 (3)
Ga1—N2—C6—C5	−1.7 (2)	C9—C10—C11—N3	177.0 (2)
Ga1—N2—C6—C7	178.59 (15)	C9—C10—C11—C12	−1.4 (3)
Ga1—N1—C1—C2	−173.87 (16)	C15—N3—C11—C10	−176.42 (19)
Ga1—N1—C5—C6	−6.3 (2)	C15—N3—C11—C12	2.0 (3)
Ga1—N1—C5—C4	173.27 (16)	C11—N3—C15—C14	−1.0 (3)
Ga1—N3—C15—C14	−179.96 (16)	C11—C10—C9—C8	−180.0 (2)
Ga1—N3—C11—C10	2.7 (2)	C2—C3—C4—C5	1.6 (3)
Ga1—N3—C11—C12	−178.88 (16)	C6—N2—C10—C9	2.6 (3)
N2—Ga1—N1—C1	−178.85 (19)	C6—N2—C10—C11	−177.91 (19)
N2—Ga1—N1—C5	4.17 (15)	C6—C5—C4—C3	−178.9 (2)
N2—Ga1—N3—C15	177.39 (19)	C12—C13—C14—C15	1.6 (3)
N2—Ga1—N3—C11	−1.61 (14)	C5—N1—C1—C2	3.0 (3)
N2—C10—C9—C8	−0.5 (3)	C5—C6—C7—C8	−179.6 (2)
N2—C10—C11—N3	−2.5 (3)	C7—C8—C9—C10	−1.7 (3)
N2—C10—C11—C12	179.1 (2)	C7—C6—C5—N1	−175.0 (2)
N2—C6—C5—N1	5.2 (3)	C7—C6—C5—C4	5.4 (3)
N2—C6—C5—C4	−174.3 (2)	C4—C3—C2—C1	−2.5 (3)
N2—C6—C7—C8	0.1 (3)	C14—C13—C12—C11	−0.6 (3)