Tris(4-tert-butyl­phen­yl)phosphine oxide

In the title compound, C₃₀H₃₉OP, the P=O bond length is 1.4866 (12) Å and the P-C bond lengths range from 1.804 (2) to 1.808 (13) Å. The molecle is located on a crystallographic mirror plane. The methyl groups of one tert-butyl group are disordered over two sites in a 0.776 (4):0.224 (4) ratio.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• Disorder in main residue
• R factor = 0.042
• wR factor = 0.117
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        C15
PLAT732_ALERT_1_B Angle   Calc    111.7(8), Rep  111.72(19) ......       4.21 su-Ra
              O1   -P1   -C1      1.555   1.555   1.555

Alert level C
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       3.59 Ratio
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.90 Ratio
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          3
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2

Alert level G
PLAT301_ALERT_3_G Note: Main Residue  Disorder ...................       9.00 Perc.
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         18

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Arylphosphines are the most frequently used as ligands in transition metal catalysis (Buchwald et al., 2006; Surry & Buchwald 2008; Xu et al., 2009). While preparing tris(4-tert-butylphenyl) phosphines, we have obtained the title compound as a side product.

The title compound, C₃₀H₃₉OP, has a P=O bond length of 1.4866 (12) Å. The P—C bond lengths range from 1.804 (2) to 1.808 (13) Å. It is located on a crystallographic mirror plane. All the bond distances and angles in the structure are within normal ranges, similar to those found in the related compounds (Baures & Silverton 1990; Shawkataly et al., 2009). The methyl groups of one tert-butyl group are disordered over two sites in a 0.776 (4):0.224 (4) ratio.

Related literature

For applications of phosphine ligands in palladium-catalysed syntheses, see: Buchwald et al. (2006); Surry & Buchwald (2008); Xu et al. (2009). For related structures, see: Baures & Silverton (1990); Shawkataly et al. (2009). For the synthesis, see: Issleib & Brack (1954).

S2. Experimental

The title compound was obtained as a side product from the reaction of PCl₃ and 4-C(CH₃)₃-C₆H₄—MgBr as described in the literature (Issleib & Brack 1954) and recrystallized from ethanol at room temperature to give the desired crystals suitable for single-crystal X-ray diffraction.

S3. Refinement

The methyl groups of one tert-butyl group are disordered over two sites, occupancies were refined and converged to 0.776 (4):0.224 (4). The rigid-group mode was used in refinement for the disordered components, and atomic displacement parameters were constrained for disordered components. H atoms attached to C atoms of the title compound were placed in geometrically idealized positions and treated as riding with C—H distances constrained to 0.93–0.96 Å, and with U_iso(H)=1.2–1.5U_eq(C).

Computing details

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

Fig. 1. The molecular structure of the title compound with displacement ellipsoids at the 30% probability level (Symmetry code A: x, -y + 1/2, z).

Tris(4-tert-butylphenyl)phosphine oxide

Crystal data

C30H39OP	Dx = 1.142 Mg m^−3
Mr = 446.58	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pnma	Cell parameters from 5668 reflections
a = 11.7986 (10) Å	θ = 2.6–28.1°
b = 20.9246 (18) Å	µ = 0.13 mm^−1
c = 10.5204 (9) Å	T = 294 K
V = 2597.3 (4) Å^3	Block, colourless
Z = 4	0.45 × 0.43 × 0.42 mm
F(000) = 968

Data collection

Bruker SMART APEX CCD area-detector diffractometer	2485 independent reflections
Radiation source: fine-focus sealed tube	2143 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
phi and ω scans	θmax = 25.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −14→14
Tmin = 0.946, Tmax = 0.949	k = −25→25
17327 measured reflections	l = −12→12

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.117	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0575P)^2 + 1.3437P] where P = (Fo^2 + 2Fc^2)/3
2485 reflections	(Δ/σ)max < 0.001
161 parameters	Δρmax = 0.38 e Å^−3
18 restraints	Δρmin = −0.30 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	Occ. (<1)
C1	0.77025 (14)	0.31883 (8)	0.30317 (15)	0.0298 (4)
C2	0.66436 (14)	0.33374 (8)	0.35431 (16)	0.0340 (4)
H2	0.6014	0.3093	0.3328	0.041*
C3	0.65284 (15)	0.38473 (8)	0.43698 (17)	0.0370 (4)
H3	0.5814	0.3944	0.4689	0.044*
C4	0.74507 (15)	0.42213 (8)	0.47393 (16)	0.0342 (4)
C5	0.84902 (15)	0.40734 (9)	0.42064 (17)	0.0400 (4)
H5	0.9119	0.4319	0.4419	0.048*
C6	0.86199 (14)	0.35678 (9)	0.33627 (17)	0.0381 (4)
H6	0.9329	0.3483	0.3016	0.046*
C7	0.72901 (17)	0.47686 (9)	0.56942 (18)	0.0422 (4)
C8	0.8417 (2)	0.50323 (12)	0.6179 (2)	0.0656 (7)
H8A	0.8839	0.4696	0.6579	0.098*
H8B	0.8276	0.5366	0.6784	0.098*
H8C	0.8844	0.5201	0.5478	0.098*
C9	0.6599 (2)	0.45282 (11)	0.6836 (2)	0.0654 (7)
H9A	0.5866	0.4390	0.6553	0.098*
H9B	0.6513	0.4868	0.7443	0.098*
H9C	0.6988	0.4176	0.7228	0.098*
C10	0.6641 (2)	0.53167 (10)	0.5049 (2)	0.0592 (6)
H10A	0.7100	0.5498	0.4387	0.089*
H10B	0.6467	0.5640	0.5667	0.089*
H10C	0.5950	0.5155	0.4691	0.089*
C11	0.6881 (2)	0.2500	0.0829 (2)	0.0299 (5)
C12	0.64869 (17)	0.30649 (9)	0.03060 (18)	0.0432 (5)
H12	0.6743	0.3453	0.0627	0.052*
C13	0.57171 (17)	0.30618 (9)	−0.06884 (18)	0.0453 (5)
H13	0.5472	0.3450	−0.1021	0.054*
C14	0.5301 (2)	0.2500	−0.1204 (2)	0.0342 (5)
C15	0.4417 (2)	0.2500	−0.2271 (2)	0.0433 (6)
C16	0.3243 (4)	0.2500	−0.1637 (5)	0.0934 (17)	0.776 (4)
H16A	0.3112	0.2906	−0.1240	0.140*	0.776 (4)
H16B	0.2671	0.2500	−0.2269	0.140*	0.776 (4)
C17	0.4487 (4)	0.3089 (2)	−0.3094 (4)	0.1069 (16)	0.776 (4)
H17A	0.3956	0.3054	−0.3782	0.160*	0.776 (4)
H17B	0.5240	0.3129	−0.3429	0.160*	0.776 (4)
H17C	0.4309	0.3460	−0.2594	0.160*	0.776 (4)
C18	0.5182 (14)	0.2500	−0.3521 (17)	0.0934 (17)	0.224 (4)
H18A	0.4698	0.2500	−0.4229	0.140*	0.224 (4)
H18B	0.5516	0.2086	−0.3543	0.140*	0.224 (4)
C19	0.3708 (5)	0.3102 (7)	−0.2313 (5)	0.1069 (16)	0.224 (4)
H19A	0.3178	0.3074	−0.3003	0.160*	0.224 (4)
H19B	0.4193	0.3465	−0.2436	0.160*	0.224 (4)
H19C	0.3303	0.3148	−0.1526	0.160*	0.224 (4)
O1	0.91419 (9)	0.2500 (7)	0.15255 (12)	0.0397 (4)
P1	0.79669 (5)	0.2500 (7)	0.20357 (5)	0.02885 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0308 (8)	0.0304 (8)	0.0281 (8)	−0.0013 (7)	−0.0028 (6)	0.0019 (7)
C2	0.0283 (8)	0.0345 (9)	0.0393 (9)	−0.0042 (7)	−0.0036 (7)	−0.0025 (7)
C3	0.0323 (9)	0.0385 (9)	0.0401 (9)	0.0005 (7)	0.0026 (7)	−0.0037 (8)
C4	0.0393 (9)	0.0304 (9)	0.0327 (9)	−0.0023 (7)	−0.0031 (7)	0.0006 (7)
C5	0.0341 (9)	0.0405 (10)	0.0455 (10)	−0.0099 (8)	−0.0034 (8)	−0.0057 (8)
C6	0.0299 (9)	0.0429 (10)	0.0414 (9)	−0.0036 (7)	0.0022 (7)	−0.0047 (8)
C7	0.0487 (11)	0.0362 (9)	0.0418 (10)	−0.0038 (8)	0.0006 (8)	−0.0080 (8)
C8	0.0646 (15)	0.0595 (14)	0.0728 (15)	−0.0078 (12)	−0.0120 (12)	−0.0304 (12)
C9	0.0945 (19)	0.0592 (14)	0.0425 (11)	−0.0148 (13)	0.0137 (12)	−0.0147 (10)
C10	0.0685 (14)	0.0424 (12)	0.0665 (14)	0.0090 (10)	0.0018 (12)	−0.0086 (11)
C11	0.0328 (12)	0.0310 (12)	0.0260 (11)	0.000	0.0004 (9)	0.000
C12	0.0580 (12)	0.0298 (9)	0.0418 (10)	−0.0022 (8)	−0.0149 (9)	−0.0015 (7)
C13	0.0597 (12)	0.0328 (10)	0.0434 (10)	0.0061 (9)	−0.0153 (9)	0.0027 (8)
C14	0.0334 (13)	0.0424 (13)	0.0270 (11)	0.000	0.0005 (10)	0.000
C15	0.0486 (16)	0.0461 (15)	0.0352 (14)	0.000	−0.0122 (12)	0.000
C16	0.055 (3)	0.157 (5)	0.068 (3)	0.000	−0.026 (2)	0.000
C17	0.121 (3)	0.117 (3)	0.083 (3)	−0.045 (3)	−0.065 (2)	0.053 (2)
C18	0.055 (3)	0.157 (5)	0.068 (3)	0.000	−0.026 (2)	0.000
C19	0.121 (3)	0.117 (3)	0.083 (3)	−0.045 (3)	−0.065 (2)	0.053 (2)
O1	0.0300 (9)	0.0473 (10)	0.0419 (10)	0.000	0.0059 (7)	0.000
P1	0.0270 (3)	0.0314 (3)	0.0282 (3)	0.000	0.0000 (2)	0.000

Geometric parameters (Å, º)

C1—C6	1.387 (2)	C11—P1	1.804 (2)
C1—C2	1.396 (2)	C12—C13	1.385 (3)
C1—P1	1.808 (13)	C12—H12	0.9300
C2—C3	1.383 (2)	C13—C14	1.384 (2)
C2—H2	0.9300	C13—H13	0.9300
C3—C4	1.396 (2)	C14—C13^i	1.384 (2)
C3—H3	0.9300	C14—C15	1.533 (3)
C4—C5	1.384 (3)	C15—C17^i	1.509 (4)
C4—C7	1.535 (2)	C15—C17	1.509 (4)
C5—C6	1.389 (2)	C15—C19^i	1.512 (13)
C5—H5	0.9300	C15—C19	1.512 (13)
C6—H6	0.9300	C15—C16	1.537 (6)
C7—C8	1.527 (3)	C15—C18	1.596 (19)
C7—C9	1.537 (3)	C16—H16A	0.9600
C7—C10	1.537 (3)	C16—H16B	0.9471
C8—H8A	0.9600	C17—H17A	0.9600
C8—H8B	0.9600	C17—H17B	0.9600
C8—H8C	0.9600	C17—H17C	0.9600
C9—H9A	0.9600	C18—H18A	0.9378
C9—H9B	0.9600	C18—H18B	0.9517
C9—H9C	0.9600	C19—H19A	0.9600
C10—H10A	0.9600	C19—H19B	0.9600
C10—H10B	0.9600	C19—H19C	0.9600
C10—H10C	0.9600	O1—P1	1.4866 (12)
C11—C12^i	1.384 (2)	P1—C1^i	1.808 (13)
C11—C12	1.384 (2)
C6—C1—C2	118.28 (15)	C14—C13—H13	118.9
C6—C1—P1	117.83 (17)	C12—C13—H13	118.9
C2—C1—P1	123.78 (18)	C13—C14—C13^i	116.2 (2)
C3—C2—C1	120.19 (15)	C13—C14—C15	121.88 (11)
C3—C2—H2	119.9	C13^i—C14—C15	121.88 (11)
C1—C2—H2	119.9	C17^i—C15—C17	109.6 (4)
C2—C3—C4	122.08 (16)	C17^i—C15—C19^i	48.2 (3)
C2—C3—H3	119.0	C17—C15—C19^i	133.9 (3)
C4—C3—H3	119.0	C17^i—C15—C19	133.9 (3)
C5—C4—C3	116.92 (16)	C17—C15—C19	48.2 (3)
C5—C4—C7	122.78 (16)	C19^i—C15—C19	112.7 (7)
C3—C4—C7	120.30 (16)	C17^i—C15—C14	112.50 (18)
C4—C5—C6	121.79 (16)	C17—C15—C14	112.50 (18)
C4—C5—H5	119.1	C19^i—C15—C14	113.5 (2)
C6—C5—H5	119.1	C19—C15—C14	113.5 (2)
C1—C6—C5	120.69 (16)	C17^i—C15—C16	107.4 (3)
C1—C6—H6	119.7	C17—C15—C16	107.4 (3)
C5—C6—H6	119.7	C19^i—C15—C16	60.9 (4)
C8—C7—C4	112.37 (16)	C19—C15—C16	60.9 (4)
C8—C7—C9	108.61 (18)	C14—C15—C16	107.2 (2)
C4—C7—C9	109.45 (15)	C17^i—C15—C18	59.7 (3)
C8—C7—C10	108.16 (17)	C17—C15—C18	59.7 (3)
C4—C7—C10	109.22 (15)	C19^i—C15—C18	106.8 (4)
C9—C7—C10	108.98 (19)	C19—C15—C18	106.8 (4)
C7—C8—H8A	109.5	C14—C15—C18	102.6 (6)
C7—C8—H8B	109.5	C16—C15—C18	150.1 (6)
H8A—C8—H8B	109.5	C15—C16—H16A	109.5
C7—C8—H8C	109.5	C15—C16—H16B	109.7
H8A—C8—H8C	109.5	H16A—C16—H16B	101.0
H8B—C8—H8C	109.5	C15—C17—H17A	109.5
C7—C9—H9A	109.5	C15—C17—H17B	109.5
C7—C9—H9B	109.5	C15—C17—H17C	109.5
H9A—C9—H9B	109.5	C15—C18—H18A	108.1
C7—C9—H9C	109.5	C15—C18—H18B	104.7
H9A—C9—H9C	109.5	H18A—C18—H18B	103.5
H9B—C9—H9C	109.5	C15—C19—H16A	90.7
C7—C10—H10A	109.5	C15—C19—H19A	109.5
C7—C10—H10B	109.5	C15—C19—H19B	109.5
H10A—C10—H10B	109.5	H19A—C19—H19B	109.5
C7—C10—H10C	109.5	C15—C19—H19C	109.5
H10A—C10—H10C	109.5	H19A—C19—H19C	109.5
H10B—C10—H10C	109.5	H19B—C19—H19C	109.5
C12^i—C11—C12	117.3 (2)	O1—P1—C1	111.72 (19)
C12^i—C11—P1	121.2 (5)	O1—P1—C11	114.10 (9)
C12—C11—P1	121.2 (5)	C1—P1—C11	106.6 (5)
C11—C12—C13	121.07 (17)	O1—P1—C1^i	111.72 (16)
C11—C12—H12	119.5	C1—P1—C1^i	105.59 (10)
C13—C12—H12	119.5	C11—P1—C1^i	106.6 (5)
C14—C13—C12	122.14 (17)
C6—C1—C2—C3	−0.8 (2)	C13—C14—C15—C17	28.3 (4)
P1—C1—C2—C3	175.4 (4)	C13^i—C14—C15—C17	−152.7 (3)
C1—C2—C3—C4	−1.1 (3)	C13—C14—C15—C19^i	−154.7 (4)
C2—C3—C4—C5	2.1 (3)	C13^i—C14—C15—C19^i	24.3 (5)
C2—C3—C4—C7	−177.92 (16)	C13—C14—C15—C19	−24.3 (5)
C3—C4—C5—C6	−1.4 (3)	C13^i—C14—C15—C19	154.7 (4)
C7—C4—C5—C6	178.71 (16)	C13—C14—C15—C16	−89.5 (2)
C2—C1—C6—C5	1.5 (3)	C13^i—C14—C15—C16	89.5 (2)
P1—C1—C6—C5	−174.9 (3)	C13—C14—C15—C18	90.5 (2)
C4—C5—C6—C1	−0.5 (3)	C13^i—C14—C15—C18	−90.5 (2)
C5—C4—C7—C8	−11.6 (3)	C6—C1—P1—O1	−9.6 (3)
C3—C4—C7—C8	168.51 (18)	C2—C1—P1—O1	174.21 (16)
C5—C4—C7—C9	−132.3 (2)	C6—C1—P1—C11	−134.9 (3)
C3—C4—C7—C9	47.8 (2)	C2—C1—P1—C11	48.9 (6)
C5—C4—C7—C10	108.5 (2)	C6—C1—P1—C1^i	112.0 (2)
C3—C4—C7—C10	−71.5 (2)	C2—C1—P1—C1^i	−64.1 (2)
C12^i—C11—C12—C13	0.9 (4)	C12^i—C11—P1—O1	86.9 (3)
P1—C11—C12—C13	174.97 (17)	C12—C11—P1—O1	−86.9 (3)
C11—C12—C13—C14	0.3 (3)	C12^i—C11—P1—C1	−149.3 (4)
C12—C13—C14—C13^i	−1.4 (4)	C12—C11—P1—C1	36.9 (4)
C12—C13—C14—C15	177.7 (2)	C12^i—C11—P1—C1^i	−36.9 (4)
C13—C14—C15—C17^i	152.7 (3)	C12—C11—P1—C1^i	149.3 (4)
C13^i—C14—C15—C17^i	−28.3 (4)

Symmetry code: (i) x, −y+1/2, z.