Tri­methyl­phosphine oxide dihydrate

Urlep, M.; Cerkovnik, J.; Lozinšek, M.

doi:10.1107/S2414314623003140

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 8| Part 4| April 2023| x230314

https://doi.org/10.1107/S2414314623003140

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Trimethylphosphine oxide dihydrate

Matic Urlep,^a Janez Cerkovnik ^a and Matic Lozinšek ^a,^b ^*‡

^aDepartment of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia, and ^bJožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
^*Correspondence e-mail: matic.lozinsek@ijs.si

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 21 March 2023; accepted 4 April 2023; online 14 April 2023)

The title hydrate, Me₃PO·2H₂O, crystallizes in the orthorhombic space group Pbca with eight formula units per unit cell. The extended structure displays O—H⋯O hydrogen bonding, with Me₃PO molecules as acceptors and water molecules acting as donors and acceptors of hydrogen bonds, forming hydrogen-bonded layers, which propagate in the ac plane.

Keywords: phosphine oxide; hydrate; hydrogen bonding; crystal structure.

CCDC reference: 2254008

Structure description

Tertiary phosphine oxides, R₃P=O (R = alkyl/aryl), are good hydrogen-bond acceptors and have been employed for co-crystallization and stabilization of hydrogen-bond donor species such as hydrogen peroxide (Arp et al., 2019 ) and di(hydroperoxy)alkanes (Ahn et al., 2015 ). However, only a limited number of simple tertiary phosphine oxide hydrates have been structurally characterized by single-crystal X-ray diffraction. For example: tricyclohexylphosphine oxide hydrate, Cy₃PO·H₂O (Cambridge Structural Database refcode ZOQHEU; Hilliard et al. 2014 ; Thomas et al., 2019 ); triphenylphosphine oxide hemihydrate, Ph₃PO·0.5H₂O (JEDTOB; Baures & Silverton, 1990 ; Baures, 1991 ; Ng, 2009 ); tri-p-tolylphosphine oxide hemihydrate p-Tol₃PO·0.5H₂O (JULBAT; Churchill et al., 1993 ); tris(2,4,6-trimethoxyphenyl)phosphine oxide hydrate, [(CH₃O)₃C₆H₂]₃PO·H₂O (WAMXIR; Chaloner et al., 1993 ); tris(2,4,6-trimethoxyphenyl)phosphine oxide dihydrate, [(CH₃O)₃C₆H₂]₃PO·2H₂O (LICVUO; Dunbar & Haefner, 1994 ); di-o-tolylphenylphosphine oxide hydrate, o-Tol₂PhPO·H₂O (POMRUH; Arp et al., 2019). The absence of crystal structures of trialkylphosphine oxide hydrates with a short alkyl chain is particularly noteworthy. Herein, the crystal structure of the title phosphine oxide hydrate is reported.

Trimethylphosphine oxide dihydrate crystallizes in the orthorhombic space group Pbca with one Me₃PO and two H₂O molecules in the asymmetric unit (Fig. 1). The P=O bond length [1.5067 (7) Å] and P—C distances [1.7805 (12), 1.7809 (11), and 1.7819 (11) Å] are in good agreement with the bond distances reported in crystal structures of trimethylphosphine oxide (FAKLUY; Engelhardt et al., 1986 ; Begimova et al., 2016 ).

Figure 1
The asymmetric unit and the atom-labelling scheme of the Me₃PO·2H₂O crystal structure. Displacement ellipsoids are depicted at the 50% probability level, hydrogen atoms are shown as spheres of arbitrary radius, and hydrogen bonds are indicated by blue dashed lines.

The trimethylphosphine oxide molecule is an acceptor of two O⋯H—O hydrogen bonds, whereas both water molecules are donors of hydrogen bonds to Me₃PO and H₂O, and acceptors of hydrogen bonds from adjacent water molecules (Table 1, Fig. 2). Two Me₃PO and six H₂O molecules form a hydrogen-bonded 16-membered ring (Fig. 2) with an R₈⁶(16) graph-set motif (Etter, 1990 ). Each water molecule participates in three rings, whereas the trimethylphosphine molecule participates in two rings. These rings are interconnected into layers that extend parallel to the ac plane, whereby each ring is surrounded by six other rings (Figs. 2, 3). Hydrogen-bonded layers and layers of Me₃P groups are stacked along the b-axis direction (Fig. 3).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O3	0.807 (17)	1.976 (18)	2.7787 (10)	173.2 (16)
O2—H3⋯O3	0.789 (18)	2.046 (18)	2.8261 (11)	169.7 (15)
O1—H2⋯O2ⁱ	0.873 (18)	1.981 (18)	2.8460 (12)	170.6 (14)
O2—H4⋯O1ⁱⁱ	0.834 (17)	1.993 (17)	2.8218 (11)	172.0 (14)
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (ii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Figure 2
Hydrogen-bonded rings (depicted by blue dashed lines) are conjoined into layers parallel to the ac-plane.

Figure 3
Crystal packing and the unit cell of Me₃PO·2H₂O viewed along the crystallographic b-axis (top) and c-axis (bottom). Hydrogen bonds are indicated by blue dashed lines.

Synthesis and crystallization

Trimethylphosphine oxide (2.3 mg) was dissolved in a mixture of acetone-d₆ (0.6 ml) and diethyl ether-d₁₀ (0.3 ml) in an NMR tube that was capped and cooled to −20 °C in an ethanol cooling bath. The Dewar flask containing the bath and sample was sealed and placed in a freezer at −80 °C. Crystals of Me₃PO·2H₂O grew within 3 days. The single crystals were examined, selected, and transferred to the diffractometer employing a previously described low-temperature crystal-mounting procedure (Lozinšek et al., 2021 ). The crystals melt at room temperature.

Refinement

Crystal data, data collection, and structure refinement details are summarized in Table 2. Positions and isotropic thermal displacement parameters of hydrogen atoms were freely refined (Cooper et al., 2010 ).

Table 2
Experimental details

Crystal data
Chemical formula	C₃H₉OP·2H₂O
M_r	128.10
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	150
a, b, c (Å)	9.33514 (8), 11.39118 (9), 13.23961 (11)
V (Å³)	1407.88 (2)
Z	8
Radiation type	Cu Kα
μ (mm⁻¹)	2.88
Crystal size (mm)	0.70 × 0.24 × 0.13

Data collection
Diffractometer	SuperNova, Dual, Cu at home/near, Atlas
Absorption correction	Gaussian (CrysAlis PRO; Rigaku OD, 2023 )
T_min, T_max	0.299, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	24977, 1451, 1417
R_int	0.023
(sin θ/λ)_max (Å⁻¹)	0.628

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.021, 0.057, 1.04
No. of reflections	1451
No. of parameters	117
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.27, −0.24
Computer programs: CrysAlis PRO (Rigaku OD, 2023), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), OLEX2 (Dolomanov et al., 2009 ), DIAMOND (Brandenburg, 2005 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 2254008

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314623003140/hb4428sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314623003140/hb4428Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314623003140/hb4428Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2023); cell refinement: CrysAlis PRO (Rigaku OD, 2023); data reduction: CrysAlis PRO (Rigaku OD, 2023); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2019/2 (Sheldrick, 2015b); molecular graphics: Olex2 1.5 (Dolomanov et al., 2009), DIAMOND (Brandenburg, 2005); software used to prepare material for publication: Olex2 1.5 (Dolomanov et al., 2009), publCIF (Westrip, 2010).

(Dimethylphosphoryl)methane dihydrate top

Crystal data top

C₃H₉OP·2H₂O	D_x = 1.209 Mg m⁻³
M_r = 128.10	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, Pbca	Cell parameters from 18569 reflections
a = 9.33514 (8) Å	θ = 3.3–75.4°
b = 11.39118 (9) Å	µ = 2.88 mm⁻¹
c = 13.23961 (11) Å	T = 150 K
V = 1407.88 (2) Å³	Block, colourless
Z = 8	0.70 × 0.24 × 0.13 mm
F(000) = 560

Data collection top

SuperNova, Dual, Cu at home/near, Atlas diffractometer	1451 independent reflections
Radiation source: micro-focus sealed X-ray tube, SuperNova (Cu) X-ray Source	1417 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.023
Detector resolution: 5.2466 pixels mm^-1	θ_max = 75.5°, θ_min = 7.0°
ω scans	h = −11→11
Absorption correction: gaussian (CrysalisPro; Rigaku OD, 2023)	k = −14→14
T_min = 0.299, T_max = 1.000	l = −16→16
24977 measured reflections

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F² > 2σ(F²)] = 0.021	w = 1/[σ²(F_o²) + (0.032P)² + 0.4017P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.057	(Δ/σ)_max = 0.001
S = 1.04	Δρ_max = 0.27 e Å⁻³
1451 reflections	Δρ_min = −0.24 e Å⁻³
117 parameters	Extinction correction: SHELXL2019/2 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0019 (4)
Primary atom site location: dual

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
P1	0.29293 (2)	0.43133 (2)	0.43709 (2)	0.01874 (11)
O3	0.38810 (7)	0.33831 (6)	0.48229 (5)	0.02332 (17)
O1	0.50092 (9)	0.18661 (7)	0.33846 (6)	0.02949 (19)
O2	0.30184 (8)	0.28005 (8)	0.68067 (6)	0.0309 (2)
C3	0.12748 (12)	0.37348 (12)	0.39205 (10)	0.0361 (3)
C1	0.25087 (15)	0.54386 (11)	0.52559 (9)	0.0360 (3)
C2	0.37390 (13)	0.50121 (11)	0.33118 (9)	0.0363 (3)
H1	0.4749 (17)	0.2314 (14)	0.3820 (13)	0.049 (4)*
H3	0.3357 (17)	0.2929 (13)	0.6272 (13)	0.044 (4)*
H1A	0.1928 (16)	0.6023 (14)	0.4936 (12)	0.049 (4)*
H3A	0.0705 (17)	0.4349 (13)	0.3682 (13)	0.049 (4)*
H2	0.5911 (19)	0.2011 (13)	0.3261 (11)	0.048 (4)*
H3B	0.0772 (19)	0.3342 (15)	0.4489 (14)	0.062 (5)*
H4	0.3659 (17)	0.2931 (12)	0.7231 (12)	0.042 (4)*
H2A	0.3129 (17)	0.5592 (14)	0.3018 (13)	0.050 (4)*
H3C	0.148 (2)	0.3195 (15)	0.3342 (15)	0.068 (5)*
H2B	0.395 (2)	0.4400 (15)	0.2808 (14)	0.063 (5)*
H1C	0.2035 (16)	0.5079 (16)	0.5804 (12)	0.055 (5)*
H2C	0.457 (2)	0.5422 (15)	0.3541 (14)	0.066 (5)*
H1B	0.337 (2)	0.5830 (16)	0.5464 (14)	0.067 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.01726 (15)	0.02106 (16)	0.01790 (16)	0.00154 (8)	0.00075 (7)	0.00121 (8)
O3	0.0247 (3)	0.0246 (3)	0.0206 (3)	0.0062 (3)	0.0018 (2)	0.0022 (3)
O1	0.0265 (4)	0.0370 (4)	0.0249 (4)	0.0048 (3)	0.0004 (3)	−0.0075 (3)
O2	0.0240 (4)	0.0472 (5)	0.0214 (4)	−0.0027 (3)	0.0013 (3)	0.0014 (3)
C3	0.0252 (5)	0.0464 (7)	0.0366 (6)	−0.0071 (5)	−0.0062 (5)	0.0026 (5)
C1	0.0422 (7)	0.0322 (5)	0.0336 (6)	0.0156 (5)	−0.0049 (6)	−0.0071 (5)
C2	0.0336 (6)	0.0393 (6)	0.0359 (6)	0.0022 (5)	0.0068 (5)	0.0174 (5)

Geometric parameters (Å, º) top

P1—O3	1.5067 (7)	C3—H3B	0.993 (18)
P1—C3	1.7819 (11)	C3—H3C	1.001 (19)
P1—C1	1.7805 (12)	C1—H1A	0.957 (17)
P1—C2	1.7809 (11)	C1—H1C	0.943 (17)
O1—H1	0.807 (17)	C1—H1B	0.96 (2)
O1—H2	0.873 (18)	C2—H2A	0.955 (17)
O2—H3	0.789 (18)	C2—H2B	0.985 (18)
O2—H4	0.834 (17)	C2—H2C	0.958 (19)
C3—H3A	0.934 (16)

O3—P1—C3	112.58 (5)	H3B—C3—H3C	113.3 (13)
O3—P1—C1	112.02 (5)	P1—C1—H1A	109.6 (10)
O3—P1—C2	112.13 (5)	P1—C1—H1C	107.3 (11)
C1—P1—C3	107.18 (7)	P1—C1—H1B	109.7 (11)
C1—P1—C2	106.85 (7)	H1A—C1—H1C	112.1 (13)
C2—P1—C3	105.64 (6)	H1A—C1—H1B	106.2 (14)
H1—O1—H2	107.7 (14)	H1C—C1—H1B	112.0 (15)
H3—O2—H4	106.5 (15)	P1—C2—H2A	112.1 (10)
P1—C3—H3A	109.3 (9)	P1—C2—H2B	107.6 (10)
P1—C3—H3B	108.8 (10)	P1—C2—H2C	108.3 (11)
P1—C3—H3C	108.3 (11)	H2A—C2—H2B	109.5 (14)
H3A—C3—H3B	108.9 (14)	H2A—C2—H2C	106.1 (13)
H3A—C3—H3C	108.2 (14)	H2B—C2—H2C	113.3 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3	0.807 (17)	1.976 (18)	2.7787 (10)	173.2 (16)
O2—H3···O3	0.789 (18)	2.046 (18)	2.8261 (11)	169.7 (15)
O1—H2···O2ⁱ	0.873 (18)	1.981 (18)	2.8460 (12)	170.6 (14)
O2—H4···O1ⁱⁱ	0.834 (17)	1.993 (17)	2.8218 (11)	172.0 (14)

Symmetry codes: (i) x+1/2, −y+1/2, −z+1; (ii) x, −y+1/2, z+1/2.

Footnotes

‡Current address: Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.

Acknowledgements

We thank the EN-FIST Center of Excellence, Ljubljana, Slovenia, for access to a single-crystal X-ray diffractometer.

Funding information

Funding for this research was provided by: Slovenian Research Agency (grant No. P1-0230; grant No. N1-0189).

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