A new synthetic route to the electron-deficient ligand tris­(3,4,5-tri­bromo­pyrazol-1-yl)phosphine oxide

The anionic tris(pyrazol­yl)borates, or scorpionates, have proven to be extremely useful ligands. Neutral tris(pyrazol­yl)methane ligands, however, are difficult to prepare and require numerous purification steps for a number of substitution patterns. We have previously outlined two different routes for accessing neutral tris­(pyra­zol­yl) ligands. We describe here an adaptation of the previously published procedures for the synthesis of the electron-poor ligand tris­(3,4,5-tri­bromo­pyrazol-1-yl)phosphine oxide, C₉Br₉N₆OP. Similar electron-deficient ligands have been proven to unlock unique chemistry for the anionic scorpionates. The title perbrominated tris­(pyrazol­yl)phosphine oxide displays a network of halogen bonds in the solid state. All the bonds in the pyrazole ring are rather similar to the reported borate analogues, which makes this mol­ecule promising as a ligand for applications where very electron-poor metal complexes are required.

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

Tris(3,4,5-tribromopyrazol-1-yl)phosphine oxide

Crystal data

C9Br9N6OP	Dx = 2.980 Mg m^−3
Mr = 958.31	Mo Kα radiation, λ = 0.71069 Å
Orthorhombic, Pna21	Cell parameters from 4782 reflections
a = 17.0187 (5) Å	θ = 1.0–27.5°
b = 9.7329 (2) Å	µ = 16.98 mm^−1
c = 25.7877 (8) Å	T = 150 K
V = 4271.5 (2) Å^3	Plate, colourless
Z = 8	0.20 × 0.20 × 0.04 mm
F(000) = 3472

Data collection

Kappa APEXII diffractometer	7037 reflections with I > 2σ(I)
phi and ω scans	Rint = 0.063
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)	θmax = 27.5°, θmin = 2.9°
Tmin = 0.496, Tmax = 1.274	h = −22→15
16015 measured reflections	k = −12→9
8616 independent reflections	l = −33→28

Refinement

Refinement on F^2	1 restraint
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0393P)^2 + 126.2737P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.070	(Δ/σ)max < 0.001
wR(F^2) = 0.166	Δρmax = 1.47 e Å^−3
S = 1.11	Δρmin = −1.37 e Å^−3
8616 reflections	Absolute structure: Refined as an inversion twin
422 parameters	Absolute structure parameter: 0.50 (4)

Special details

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

Refinement. Refined as a 2-component inversion twin

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

	x	y	z	Uiso*/Ueq
Br1	0.39024 (17)	1.2163 (3)	−0.02071 (13)	0.0391 (7)
Br2	0.22814 (15)	1.4299 (2)	0.01788 (12)	0.0320 (6)
Br3	0.10717 (15)	1.2151 (3)	0.10181 (12)	0.0336 (6)
Br4	0.07984 (17)	0.8022 (3)	−0.07622 (11)	0.0401 (7)
Br5	0.01298 (15)	0.5386 (3)	0.01210 (12)	0.0372 (7)
Br6	0.11237 (16)	0.6097 (2)	0.13398 (11)	0.0303 (6)
Br7	0.43723 (16)	0.5501 (3)	0.05212 (14)	0.0431 (8)
Br8	0.47273 (16)	0.6178 (3)	0.18860 (14)	0.0461 (8)
Br9	0.32315 (17)	0.8624 (3)	0.22677 (12)	0.0365 (6)
P1	0.2122 (3)	0.9111 (6)	0.1114 (3)	0.0225 (13)
O1	0.1726 (10)	0.9385 (18)	0.1596 (7)	0.030 (4)
N1	0.2420 (11)	1.050 (2)	0.0794 (9)	0.028 (5)
N2	0.3120 (11)	1.047 (2)	0.0499 (9)	0.025 (4)
N3	0.1581 (11)	0.8264 (19)	0.0667 (8)	0.021 (4)
N4	0.1521 (10)	0.8775 (19)	0.0154 (8)	0.019 (4)
N5	0.2930 (12)	0.8104 (19)	0.1191 (10)	0.030 (5)
N6	0.3211 (15)	0.7386 (19)	0.0774 (9)	0.027 (5)
C1	0.3133 (14)	1.168 (2)	0.0262 (11)	0.026 (3)
C2	0.2465 (15)	1.253 (2)	0.0391 (13)	0.026 (3)
C3	0.2028 (13)	1.170 (2)	0.0734 (10)	0.020 (5)
C4	0.1056 (14)	0.786 (3)	−0.0073 (11)	0.026 (3)
C5	0.0802 (13)	0.680 (2)	0.0267 (11)	0.026 (3)
C6	0.1172 (15)	0.710 (2)	0.0732 (10)	0.022 (5)
C7	0.3798 (14)	0.669 (2)	0.0944 (11)	0.026 (3)
C8	0.3955 (13)	0.693 (2)	0.1466 (11)	0.026 (3)
C9	0.3390 (14)	0.783 (3)	0.1629 (12)	0.029 (6)
Br10	−0.13606 (19)	0.7068 (3)	0.39935 (14)	0.0452 (8)
Br11	0.03296 (16)	0.9123 (3)	0.36622 (13)	0.0381 (7)
Br12	0.14363 (16)	0.7084 (3)	0.27430 (13)	0.0383 (7)
Br13	−0.18452 (17)	0.0266 (3)	0.31455 (13)	0.0411 (7)
Br14	−0.22028 (16)	0.1165 (3)	0.18078 (13)	0.0406 (7)
Br15	−0.07276 (16)	0.3704 (3)	0.14798 (11)	0.0335 (6)
Br16	0.17763 (17)	0.3324 (3)	0.45034 (12)	0.0443 (8)
Br17	0.24532 (17)	0.0576 (3)	0.36627 (13)	0.0391 (7)
Br18	0.13929 (16)	0.1067 (2)	0.24501 (11)	0.0308 (6)
P2	0.0362 (4)	0.4069 (6)	0.2645 (3)	0.0235 (13)
O2	0.0791 (11)	0.4346 (18)	0.2167 (7)	0.029 (4)
N7	0.0041 (12)	0.5473 (19)	0.2942 (9)	0.027 (5)
N8	−0.0604 (12)	0.541 (2)	0.3278 (9)	0.026 (3)
N9	−0.0433 (12)	0.304 (2)	0.2561 (9)	0.028 (5)
N10	−0.0686 (13)	0.223 (2)	0.2974 (9)	0.026 (3)
N11	0.0876 (11)	0.3245 (19)	0.3101 (9)	0.024 (5)
N12	0.0948 (12)	0.384 (2)	0.3588 (9)	0.026 (3)
C10	−0.0581 (14)	0.660 (3)	0.3517 (10)	0.029 (6)
C11	0.0071 (18)	0.746 (2)	0.3401 (12)	0.027 (3)
C12	0.0474 (17)	0.667 (3)	0.3056 (11)	0.030 (6)
C13	−0.1319 (14)	0.155 (2)	0.2745 (13)	0.033 (6)
C14	−0.1410 (16)	0.190 (2)	0.2228 (11)	0.027 (3)
C15	−0.0896 (15)	0.285 (2)	0.2120 (10)	0.021 (5)
C16	0.1447 (13)	0.302 (3)	0.3821 (11)	0.027 (6)
C17	0.1718 (16)	0.190 (2)	0.3523 (10)	0.027 (3)
C18	0.1332 (13)	0.210 (2)	0.3062 (10)	0.020 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0399 (15)	0.0318 (13)	0.046 (2)	0.0056 (12)	0.0190 (14)	0.0083 (13)
Br2	0.0342 (12)	0.0245 (11)	0.0373 (17)	0.0028 (10)	−0.0005 (12)	0.0060 (11)
Br3	0.0263 (13)	0.0337 (12)	0.0409 (19)	0.0056 (11)	0.0078 (12)	0.0044 (12)
Br4	0.0442 (15)	0.0556 (17)	0.0204 (15)	0.0006 (13)	−0.0084 (12)	0.0067 (12)
Br5	0.0318 (12)	0.0323 (13)	0.047 (2)	−0.0065 (10)	−0.0095 (12)	−0.0023 (12)
Br6	0.0411 (14)	0.0248 (11)	0.0251 (15)	−0.0012 (10)	0.0009 (11)	0.0041 (10)
Br7	0.0302 (13)	0.0348 (13)	0.064 (2)	0.0032 (11)	0.0070 (13)	−0.0126 (14)
Br8	0.0310 (14)	0.0429 (16)	0.064 (2)	−0.0009 (12)	−0.0172 (14)	0.0140 (15)
Br9	0.0434 (14)	0.0435 (15)	0.0226 (15)	−0.0097 (12)	−0.0035 (12)	0.0010 (12)
P1	0.023 (3)	0.017 (3)	0.027 (4)	0.000 (2)	0.002 (3)	−0.001 (2)
O1	0.030 (9)	0.036 (9)	0.023 (10)	0.000 (8)	0.003 (7)	−0.012 (8)
N1	0.018 (9)	0.035 (11)	0.030 (14)	−0.006 (8)	−0.003 (8)	−0.011 (9)
N2	0.023 (9)	0.028 (10)	0.024 (12)	−0.007 (8)	0.000 (8)	−0.006 (8)
N3	0.028 (10)	0.019 (9)	0.015 (11)	0.010 (8)	−0.008 (8)	−0.004 (8)
N4	0.023 (8)	0.027 (9)	0.008 (10)	0.006 (7)	0.009 (7)	0.007 (8)
N5	0.025 (10)	0.017 (9)	0.047 (16)	0.005 (8)	−0.009 (10)	−0.013 (9)
N6	0.043 (12)	0.017 (9)	0.021 (13)	0.007 (8)	0.006 (9)	−0.008 (8)
C1	0.030 (7)	0.023 (6)	0.026 (9)	0.008 (6)	0.004 (6)	−0.006 (6)
C2	0.014 (6)	0.026 (7)	0.036 (10)	−0.007 (5)	0.004 (6)	0.005 (6)
C3	0.019 (10)	0.012 (9)	0.029 (15)	0.006 (8)	0.003 (9)	0.001 (9)
C4	0.030 (7)	0.023 (6)	0.026 (9)	0.008 (6)	0.004 (6)	−0.006 (6)
C5	0.014 (6)	0.026 (7)	0.036 (10)	−0.007 (5)	0.004 (6)	0.005 (6)
C6	0.033 (13)	0.022 (11)	0.013 (13)	0.001 (10)	−0.007 (10)	0.001 (9)
C7	0.030 (7)	0.023 (6)	0.026 (9)	0.008 (6)	0.004 (6)	−0.006 (6)
C8	0.014 (6)	0.026 (7)	0.036 (10)	−0.007 (5)	0.004 (6)	0.005 (6)
C9	0.014 (11)	0.040 (14)	0.034 (18)	−0.007 (10)	−0.004 (10)	0.003 (12)
Br10	0.0499 (17)	0.0422 (15)	0.044 (2)	−0.0098 (14)	0.0201 (15)	−0.0109 (15)
Br11	0.0415 (14)	0.0249 (11)	0.0479 (19)	−0.0042 (10)	0.0016 (13)	−0.0096 (12)
Br12	0.0294 (14)	0.0332 (13)	0.052 (2)	−0.0050 (11)	0.0057 (13)	−0.0032 (14)
Br13	0.0422 (15)	0.0377 (14)	0.0435 (19)	−0.0165 (12)	0.0034 (13)	0.0032 (13)
Br14	0.0342 (14)	0.0412 (15)	0.046 (2)	−0.0009 (12)	−0.0140 (13)	−0.0068 (13)
Br15	0.0399 (14)	0.0386 (13)	0.0219 (15)	0.0073 (11)	−0.0039 (11)	0.0025 (11)
Br16	0.0459 (16)	0.0613 (18)	0.0259 (17)	0.0177 (14)	−0.0133 (13)	−0.0138 (14)
Br17	0.0398 (14)	0.0372 (13)	0.0403 (18)	0.0155 (11)	−0.0094 (13)	−0.0047 (13)
Br18	0.0438 (15)	0.0249 (11)	0.0236 (15)	0.0032 (10)	−0.0004 (11)	−0.0056 (10)
P2	0.031 (3)	0.025 (3)	0.014 (3)	0.000 (2)	−0.007 (2)	−0.003 (2)
O2	0.047 (10)	0.037 (9)	0.004 (9)	0.005 (8)	−0.005 (7)	0.000 (7)
N7	0.035 (11)	0.019 (9)	0.026 (13)	0.000 (8)	−0.003 (9)	0.007 (8)
N8	0.029 (6)	0.030 (6)	0.020 (7)	−0.004 (5)	0.006 (5)	−0.001 (5)
N9	0.032 (11)	0.032 (11)	0.019 (13)	0.003 (9)	−0.006 (9)	0.010 (9)
N10	0.029 (6)	0.030 (6)	0.020 (7)	−0.004 (5)	0.006 (5)	−0.001 (5)
N11	0.019 (9)	0.022 (9)	0.030 (13)	0.006 (8)	0.018 (9)	0.002 (8)
N12	0.029 (6)	0.030 (6)	0.020 (7)	−0.004 (5)	0.006 (5)	−0.001 (5)
C10	0.031 (12)	0.045 (14)	0.013 (13)	0.008 (11)	−0.012 (10)	0.004 (11)
C11	0.039 (8)	0.021 (6)	0.022 (9)	0.002 (6)	−0.006 (6)	0.007 (6)
C12	0.047 (15)	0.024 (11)	0.020 (15)	0.011 (11)	−0.009 (12)	0.001 (10)
C13	0.026 (12)	0.016 (10)	0.06 (2)	−0.006 (9)	0.012 (12)	−0.003 (11)
C14	0.039 (8)	0.021 (6)	0.022 (9)	0.002 (6)	−0.006 (6)	0.007 (6)
C15	0.039 (14)	0.011 (9)	0.014 (13)	0.006 (10)	−0.010 (10)	0.007 (9)
C16	0.016 (10)	0.028 (12)	0.036 (17)	0.014 (9)	0.000 (10)	0.000 (10)
C17	0.039 (8)	0.021 (6)	0.022 (9)	0.002 (6)	−0.006 (6)	0.007 (6)
C18	0.015 (10)	0.017 (10)	0.028 (15)	−0.007 (9)	0.008 (9)	−0.002 (10)

Geometric parameters (Å, º)

Br1—C1	1.84 (3)	Br10—C10	1.86 (3)
Br2—C2	1.83 (2)	Br11—C11	1.81 (2)
Br3—C3	1.84 (2)	Br12—C12	1.87 (3)
Br4—C4	1.84 (3)	Br13—C13	1.85 (3)
Br5—C5	1.83 (2)	Br14—C14	1.87 (3)
Br6—C6	1.85 (2)	Br15—C15	1.87 (2)
Br7—C7	1.87 (2)	Br16—C16	1.87 (3)
Br8—C8	1.85 (3)	Br17—C17	1.83 (2)
Br9—C9	1.84 (3)	Br18—C18	1.87 (3)
P1—O1	1.439 (19)	P2—O2	1.457 (19)
P1—N1	1.67 (2)	P2—N7	1.66 (2)
P1—N3	1.69 (2)	P2—N11	1.67 (2)
P1—N5	1.70 (2)	P2—N9	1.70 (2)
N1—C3	1.35 (3)	N7—N8	1.40 (3)
N1—N2	1.41 (3)	N7—C12	1.41 (3)
N2—C1	1.33 (3)	N8—C10	1.32 (3)
N3—C6	1.34 (3)	N9—N10	1.39 (3)
N3—N4	1.42 (3)	N9—C15	1.40 (3)
N4—C4	1.33 (3)	N10—C13	1.40 (3)
N5—N6	1.37 (3)	N11—C18	1.36 (3)
N5—C9	1.40 (3)	N11—N12	1.39 (3)
N6—C7	1.28 (3)	N12—C16	1.31 (3)
C1—C2	1.44 (3)	C10—C11	1.42 (4)
C2—C3	1.41 (3)	C11—C12	1.36 (4)
C4—C5	1.42 (4)	C13—C14	1.38 (4)
C5—C6	1.38 (4)	C14—C15	1.30 (4)
C7—C8	1.39 (4)	C16—C17	1.41 (4)
C8—C9	1.36 (4)	C17—C18	1.37 (4)
O1—P1—N1	114.8 (11)	O2—P2—N7	113.7 (11)
O1—P1—N3	115.1 (11)	O2—P2—N11	115.0 (10)
N1—P1—N3	103.1 (11)	N7—P2—N11	104.0 (11)
O1—P1—N5	112.6 (12)	O2—P2—N9	113.7 (11)
N1—P1—N5	106.3 (11)	N7—P2—N9	106.4 (11)
N3—P1—N5	103.8 (10)	N11—P2—N9	102.9 (10)
C3—N1—N2	112 (2)	N8—N7—C12	108 (2)
C3—N1—P1	127.4 (17)	N8—N7—P2	120.5 (15)
N2—N1—P1	120.3 (16)	C12—N7—P2	127.3 (19)
C1—N2—N1	103.9 (19)	C10—N8—N7	103 (2)
C6—N3—N4	112.0 (19)	N10—N9—C15	112 (2)
C6—N3—P1	127.7 (18)	N10—N9—P2	118.9 (17)
N4—N3—P1	120.3 (16)	C15—N9—P2	129.3 (18)
C4—N4—N3	102.6 (19)	N9—N10—C13	101 (2)
N6—N5—C9	110 (2)	C18—N11—N12	111 (2)
N6—N5—P1	119.0 (19)	C18—N11—P2	130 (2)
C9—N5—P1	131 (2)	N12—N11—P2	118.7 (15)
C7—N6—N5	106 (2)	C16—N12—N11	102.3 (19)
N2—C1—C2	113 (2)	N8—C10—C11	116 (2)
N2—C1—Br1	122.6 (17)	N8—C10—Br10	120 (2)
C2—C1—Br1	124.5 (19)	C11—C10—Br10	124 (2)
C3—C2—C1	104 (2)	C12—C11—C10	102 (2)
C3—C2—Br2	129.3 (19)	C12—C11—Br11	129 (2)
C1—C2—Br2	127 (2)	C10—C11—Br11	129 (2)
N1—C3—C2	108 (2)	C11—C12—N7	110 (3)
N1—C3—Br3	126.6 (17)	C11—C12—Br12	127 (2)
C2—C3—Br3	125.7 (17)	N7—C12—Br12	123 (2)
N4—C4—C5	113 (2)	C14—C13—N10	112 (2)
N4—C4—Br4	120.5 (19)	C14—C13—Br13	130 (2)
C5—C4—Br4	126 (2)	N10—C13—Br13	117 (2)
C6—C5—C4	104 (2)	C15—C14—C13	108 (2)
C6—C5—Br5	128.3 (19)	C15—C14—Br14	129 (2)
C4—C5—Br5	127 (2)	C13—C14—Br14	123.0 (19)
N3—C6—C5	108 (2)	C14—C15—N9	108 (2)
N3—C6—Br6	125.1 (18)	C14—C15—Br15	127 (2)
C5—C6—Br6	127.2 (18)	N9—C15—Br15	124.9 (18)
N6—C7—C8	113 (2)	N12—C16—C17	116 (2)
N6—C7—Br7	122 (2)	N12—C16—Br16	121.8 (19)
C8—C7—Br7	124.5 (18)	C17—C16—Br16	122.4 (18)
C9—C8—C7	106 (2)	C18—C17—C16	102 (2)
C9—C8—Br8	125 (2)	C18—C17—Br17	127 (2)
C7—C8—Br8	129.6 (19)	C16—C17—Br17	131 (2)
C8—C9—N5	106 (2)	N11—C18—C17	109 (2)
C8—C9—Br9	130 (2)	N11—C18—Br18	122 (2)
N5—C9—Br9	123.9 (19)	C17—C18—Br18	129.0 (18)