Metastable β-phase of benzophenone: independent structure determinations via X-ray powder ­diffraction and single crystal studies

Benzophenone was the first organic molecular material to be identified as polymorphic. It is well known that benzophenone crystallizes in a stable orthorhombic α-form (m.p. 321 K) with space group P2₁2₁2₁ and a = 10.28, b = 12.12, c = 7.99 Å, [Girdwood (1998). Ph.D. thesis. Strathclyde University, Glasgow, Scotland]. Here we report two separate structure determinations of the metastable β-form (m.p. 297–299 K). Crystalline material of the metastable polymorph was obtained from a melt supercooled to ∼243 K. The structure was determined from X-ray powder diffraction data by employing a novel, computational systematic search procedure to identify trial packing arrangements for subsequent refinement. Unit-cell and space-group information, determined from indexing the powder diffraction data, was used to define the search space. The structure was also determined from single-crystal diffraction data at room temperature and at 223 K. The metastable phase is monoclinic with space group C2/c and a = 16.22, b = 8.15, c = 16.33 Å, β = 112.91° (at 223 K). The structures derived from the individual techniques are qualitatively the same. They are compared both with each other and with the stable polymorph and other benzophenone derivatives.

Computing details

Program(s) used to refine structure: GSAS for MSBENZ2.

Figures

(MSBENZ2)

Crystal data

C13H10O	β = 112.911 (5)°
Mr = 182.22	V = 1988.35 (13) Å^3
Monoclinic, C2/c	Z = 8
Hall symbol: -C 2yc	Dx = 1.218 Mg m^−3
a = 16.2219 (11) Å	Cu Kα radiation, λ = 1.54178 Å
b = 8.1468 (3) Å	?, ? × ? × ? mm
c = 16.3340 (7) Å

Data collection

2θmin = 11.26°, 2θmax = 59.96°, 2θstep = 0.02°

Refinement

Rp = ?	? data points
Rwp = ?	23 parameters
Rexp = ?
χ^2 = 8.644

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

	x	y	z	Uiso*/Ueq
O1	0.3802 (6)	0.151 (2)	0.9751 (12)	0.0*
C1	0.3784 (6)	0.242 (2)	0.9228 (5)	0.0*
C2	0.4685 (7)	0.3183 (11)	0.9157 (5)	0.0*
C3	0.5480 (8)	0.2240 (13)	0.9436 (8)	0.0*
C4	0.6261 (8)	0.2898 (18)	0.9375 (7)	0.0*
C5	0.6248 (9)	0.4500 (18)	0.9033 (5)	0.0*
C6	0.5453 (10)	0.5443 (16)	0.8754 (9)	0.0*
C7	0.4671 (9)	0.4785 (14)	0.8816 (8)	0.0*
C8	0.2910 (8)	0.2968 (11)	0.8547 (7)	0.0*
C9	0.2211 (7)	0.3455 (16)	0.8809 (7)	0.0*
C10	0.1380 (8)	0.3972 (16)	0.8161 (6)	0.0*
C11	0.1247 (7)	0.4002 (15)	0.7252 (7)	0.0*
C12	0.1947 (7)	0.3515 (18)	0.6990 (7)	0.0*
C13	0.2778 (7)	0.2998 (16)	0.7638 (7)	0.0*

(223K)

Crystal data

C13H10O	β = 112.82 (2)°
Mr = 182.22	V = 1966.2 (7) Å^3
Monoclinic, C2/c	Z = 8
Hall symbol: -C 2yc	Dx = 1.231 Mg m^−3
a = 16.200 (4) Å	Cu Kα radiation, λ = 1.54178 Å
b = 8.104 (1) Å	× × mm
c = 16.248 (4) Å

Data collection

h = ?→?	l = ?→?
k = ?→?

Refinement

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

	x	y	z	Uiso*/Ueq
O1	0.37698 (8)	0.1592 (2)	0.97451 (8)	0.0539 (6)
C1	0.3758 (1)	0.2532 (2)	0.9152 (1)	0.0389 (8)
C2	0.4603 (1)	0.3130 (2)	0.9099 (1)	0.0374 (8)
C3	0.5373 (1)	0.2183 (2)	0.9444 (1)	0.0481 (10)
C4	0.6166 (1)	0.2743 (3)	0.9420 (1)	0.0574 (11)
C5	0.6207 (1)	0.4289 (3)	0.9073 (1)	0.0583 (12)
C6	0.5449 (1)	0.5242 (3)	0.8737 (1)	0.0562 (11)
C7	0.4648 (1)	0.4668 (2)	0.8739 (1)	0.0477 (10)
C8	0.2884 (1)	0.3088 (2)	0.8460 (1)	0.0380 (9)
C9	0.2187 (1)	0.3516 (2)	0.8713 (1)	0.0488 (10)
C10	0.1369 (1)	0.3984 (3)	0.8069 (2)	0.0595 (12)
C11	0.1238 (1)	0.3975 (2)	0.7180 (2)	0.0621 (12)
C12	0.1924 (1)	0.3539 (2)	0.6924 (1)	0.0571 (11)
C13	0.2750 (1)	0.3113 (2)	0.7566 (1)	0.0463 (9)
H3	0.533 (1)	0.108 (2)	0.967 (1)	0.057 (5)
H4	0.667 (1)	0.204 (3)	0.963 (1)	0.071 (6)
H5	0.680 (1)	0.467 (2)	0.908 (1)	0.063 (5)
H6	0.548 (1)	0.633 (2)	0.850 (1)	0.067 (5)
H7	0.412 (1)	0.535 (2)	0.850 (1)	0.057 (5)
H9	0.230 (1)	0.349 (2)	0.935 (1)	0.067 (6)
H10	0.092 (1)	0.429 (2)	0.827 (1)	0.066 (5)
H11	0.064 (1)	0.432 (3)	0.672 (1)	0.080 (6)
H12	0.185 (1)	0.354 (2)	0.630 (1)	0.070 (6)
H13	0.324 (1)	0.278 (2)	0.739 (1)	0.051 (5)