sp-9-Acetyl­fluorene, the initial acetyl­ation product of 9-fluorenyl­lithium

The reaction of 9-fluorenyl­lithium with acetyl chloride (tetra­hydro­furan, 213 K, under argon) provided four products which we have isolated and whose structures we have unequivocally identified for the first time. That of the initially formed component, 9-acetyl­fluorene (C₁₅H₁₂O), described here, shows it to be exclusively the sp rotamer in its crystalline form. The acetyl C-C=O plane is essentially perpendicular to the planar fluorene ring and there is no indication of rotational restriction. In contrast, related 9-pivaloyl­fluorene, which we reported previously, is rotationally restricted and exists exclusively as its ap rotamer, in which the pivaloyl C-C=O plane is also almost perpendicular to the fluorene ring.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: PROCESS in TEXSAN (Molecular Structure Corporation, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: LS in TEXSAN and SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: TEXSAN, SHELXL97, and PLATON (Spek, 2000).

sp-9-Acetylfluorene

Crystal data

C15H12O	Dx = 1.217 Mg m^−3
Mr = 208.25	Melting point = 347–348 K
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71069 Å
a = 11.253 (4) Å	Cell parameters from 23 reflections
b = 5.740 (6) Å	θ = 2.3–8.1°
c = 17.782 (6) Å	µ = 0.08 mm^−1
β = 98.19 (3)°	T = 296 K
V = 1136.9 (13) Å^3	Prism, colourless
Z = 4	0.49 × 0.43 × 0.38 mm
F(000) = 440

Data collection

Rigaku AFC-5S diffractometer	Rint = 0.043
Radiation source: sealed tube	θmax = 25.2°, θmin = 2.0°
Graphite monochromator	h = 0→13
ω scans	k = 0→6
2109 measured reflections	l = −21→20
2001 independent reflections	3 standard reflections every 100 reflections
981 reflections with I > 2σ(I)	intensity decay: −0.3%

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)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.156	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0747P)^2 + 0.0629P] where P = (Fo^2 + 2Fc^2)/3
2001 reflections	(Δ/σ)max < 0.001
146 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	−0.0753 (2)	0.5733 (4)	0.41839 (14)	0.0854 (8)
C1	0.2326 (2)	0.2426 (5)	0.43818 (16)	0.0592 (7)
C2	0.3244 (2)	0.0839 (6)	0.45510 (18)	0.0666 (9)
C3	0.3341 (2)	−0.1050 (6)	0.40848 (19)	0.0707 (9)
C4	0.2529 (2)	−0.1404 (5)	0.34437 (18)	0.0616 (8)
C4a	0.1596 (2)	0.0179 (5)	0.32713 (15)	0.0484 (7)
C4b	0.0617 (2)	0.0272 (5)	0.26332 (15)	0.0516 (7)
C5	0.0321 (3)	−0.1187 (6)	0.20109 (17)	0.0695 (9)
C6	−0.0669 (3)	−0.0666 (7)	0.14903 (19)	0.0833 (11)
C7	−0.1356 (3)	0.1277 (7)	0.1581 (2)	0.0848 (11)
C8	−0.1075 (3)	0.2762 (6)	0.21952 (18)	0.0714 (9)
C8a	−0.0075 (2)	0.2243 (5)	0.27152 (15)	0.0520 (7)
C9	0.0418 (2)	0.3560 (5)	0.34278 (15)	0.0529 (7)
C9a	0.1500 (2)	0.2089 (4)	0.37388 (15)	0.0471 (7)
C10	−0.0491 (2)	0.3829 (5)	0.39785 (16)	0.0549 (7)
C11	−0.1065 (3)	0.1687 (5)	0.4228 (2)	0.0787 (10)
H1	0.2263	0.3703	0.4696	0.071*
H2	0.3804	0.1045	0.4984	0.080*
H3	0.3968	−0.2101	0.4207	0.085*
H4	0.2601	−0.2679	0.3131	0.074*
H5	0.0785	−0.2495	0.1947	0.083*
H6	−0.0876	−0.1634	0.1073	0.100*
H7	−0.2022	0.1596	0.1223	0.102*
H8	−0.1543	0.4065	0.2256	0.086*
H9	0.0690	0.5104	0.3289	0.063*
H11a	−0.1145	0.1819	0.4757	0.118*
H11b	−0.0576	0.0360	0.4154	0.118*
H11c	−0.1844	0.1499	0.3936	0.118*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0847 (16)	0.0616 (15)	0.111 (2)	0.0168 (12)	0.0192 (13)	−0.0204 (13)
C1	0.0522 (15)	0.0620 (18)	0.0636 (18)	−0.0020 (14)	0.0089 (14)	−0.0074 (16)
C2	0.0440 (15)	0.084 (2)	0.069 (2)	0.0035 (16)	0.0007 (14)	0.0016 (19)
C3	0.0448 (16)	0.077 (2)	0.092 (2)	0.0120 (16)	0.0142 (17)	0.007 (2)
C4	0.0510 (15)	0.0536 (17)	0.085 (2)	0.0035 (15)	0.0253 (15)	−0.0064 (17)
C4a	0.0401 (13)	0.0483 (15)	0.0591 (15)	−0.0063 (12)	0.0157 (12)	−0.0017 (14)
C4b	0.0483 (15)	0.0531 (16)	0.0555 (17)	−0.0133 (13)	0.0148 (13)	−0.0047 (14)
C5	0.0676 (19)	0.075 (2)	0.068 (2)	−0.0221 (17)	0.0188 (16)	−0.0143 (18)
C6	0.080 (2)	0.105 (3)	0.064 (2)	−0.035 (2)	0.0062 (19)	−0.013 (2)
C7	0.061 (2)	0.119 (3)	0.069 (2)	−0.025 (2)	−0.0055 (17)	0.013 (2)
C8	0.0575 (18)	0.081 (2)	0.073 (2)	−0.0030 (17)	0.0011 (16)	0.0119 (19)
C8a	0.0464 (14)	0.0549 (17)	0.0545 (16)	−0.0099 (13)	0.0063 (13)	0.0052 (14)
C9	0.0494 (15)	0.0388 (14)	0.0703 (18)	0.0005 (12)	0.0080 (13)	0.0036 (14)
C9a	0.0398 (14)	0.0455 (15)	0.0569 (16)	−0.0016 (11)	0.0096 (12)	0.0016 (13)
C10	0.0454 (14)	0.0515 (17)	0.0647 (18)	0.0086 (14)	−0.0022 (13)	−0.0056 (15)
C11	0.068 (2)	0.073 (2)	0.101 (3)	0.0048 (18)	0.0351 (18)	0.008 (2)

Geometric parameters (Å, º)

O1—C10	1.202 (3)	C9—C9a	1.519 (3)
C1—C2	1.378 (4)	C9—C10	1.521 (4)
C1—C9a	1.381 (4)	C10—C11	1.486 (4)
C2—C3	1.379 (4)	C1—H1	0.9300
C3—C4	1.371 (4)	C2—H2	0.9300
C4—C4a	1.389 (4)	C3—H3	0.9300
C4a—C9a	1.389 (4)	C4—H4	0.9300
C4a—C4b	1.466 (4)	C5—H5	0.9300
C4b—C5	1.390 (4)	C6—H6	0.9300
C4b—C8a	1.393 (4)	C7—H7	0.9300
C5—C6	1.376 (4)	C8—H8	0.9300
C6—C7	1.380 (5)	C9—H9	0.9800
C7—C8	1.386 (4)	C11—H11a	0.9600
C8—C8a	1.383 (4)	C11—H11b	0.9600
C8a—C9	1.512 (4)	C11—H11c	0.9600
C2—C1—C9a	118.9 (3)	C2—C1—H1	120.5
C1—C2—C3	120.6 (3)	C9a—C1—H1	120.5
C4—C3—C2	121.1 (3)	C1—C2—H2	119.7
C3—C4—C4a	118.7 (3)	C3—C2—H2	119.7
C4—C4a—C9a	120.4 (3)	C4—C3—H3	119.5
C4—C4a—C4b	131.0 (3)	C2—C3—H3	119.5
C9a—C4a—C4b	108.7 (2)	C3—C4—H4	120.7
C5—C4b—C8a	119.9 (3)	C4a—C4—H4	120.7
C5—C4b—C4a	131.5 (3)	C6—C5—H5	120.5
C8a—C4b—C4a	108.6 (2)	C4b—C5—H5	120.5
C6—C5—C4b	118.9 (3)	C5—C6—H6	119.6
C5—C6—C7	120.7 (3)	C7—C6—H6	119.6
C6—C7—C8	121.4 (3)	C6—C7—H7	119.3
C8a—C8—C7	117.8 (3)	C8—C7—H7	119.3
C8—C8a—C4b	121.3 (3)	C8a—C8—H8	121.1
C8—C8a—C9	128.3 (3)	C7—C8—H8	121.1
C4b—C8a—C9	110.5 (2)	C8a—C9—H9	109.4
C8a—C9—C9a	101.9 (2)	C9a—C9—H9	109.4
C8a—C9—C10	113.0 (2)	C10—C9—H9	109.4
C9a—C9—C10	113.5 (2)	C10—C11—H11a	109.5
C1—C9a—C4a	120.4 (2)	C10—C11—H11b	109.5
C1—C9a—C9	129.3 (3)	H11a—C11—H11b	109.5
C4a—C9a—C9	110.4 (2)	C10—C11—H11c	109.5
O1—C10—C11	121.7 (3)	H11a—C11—H11c	109.5
O1—C10—C9	120.3 (3)	H11b—C11—H11c	109.5
C11—C10—C9	118.0 (2)
C9a—C1—C2—C3	0.3 (4)	C4a—C4b—C8a—C9	−0.4 (3)
C1—C2—C3—C4	−0.1 (4)	C8—C8a—C9—C9a	179.5 (3)
C2—C3—C4—C4a	−0.2 (4)	C4b—C8a—C9—C9a	0.7 (3)
C3—C4—C4a—C9a	0.5 (4)	C8—C8a—C9—C10	57.3 (4)
C3—C4—C4a—C4b	179.3 (3)	C4b—C8a—C9—C10	−121.5 (2)
C4—C4a—C4b—C5	0.2 (5)	C2—C1—C9a—C4a	0.0 (4)
C9a—C4a—C4b—C5	179.1 (3)	C2—C1—C9a—C9	−179.9 (3)
C4—C4a—C4b—C8a	−179.0 (3)	C4—C4a—C9a—C1	−0.3 (4)
C9a—C4a—C4b—C8a	0.0 (3)	C4b—C4a—C9a—C1	−179.4 (2)
C8a—C4b—C5—C6	−0.9 (4)	C4—C4a—C9a—C9	179.6 (2)
C4a—C4b—C5—C6	179.9 (3)	C4b—C4a—C9a—C9	0.5 (3)
C4b—C5—C6—C7	0.2 (5)	C8a—C9—C9a—C1	179.2 (3)
C5—C6—C7—C8	0.1 (5)	C10—C9—C9a—C1	−59.0 (4)
C6—C7—C8—C8a	0.3 (5)	C8a—C9—C9a—C4a	−0.7 (3)
C7—C8—C8a—C4b	−1.1 (4)	C10—C9—C9a—C4a	121.1 (2)
C7—C8—C8a—C9	−179.7 (3)	C8a—C9—C10—O1	−123.2 (3)
C5—C4b—C8a—C8	1.4 (4)	C9a—C9—C10—O1	121.4 (3)
C4a—C4b—C8a—C8	−179.3 (2)	C8a—C9—C10—C11	54.7 (3)
C5—C4b—C8a—C9	−179.7 (2)	C9a—C9—C10—C11	−60.7 (3)