[N,N′-Bis(2,4,6-trimethyl­phen­yl)ethane-1,2-diimine-κ2N,N′]tetra­carbonyl­chromium(0)

Landman, M.; Fraser, R.; Pretorius, R.; Prinsloo, R.; Liles, D.C.; Rooyen, P.H. van

doi:10.1107/S1600536812024786

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 7| July 2012| Page m930

https://doi.org/10.1107/S1600536812024786

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[N,N′-Bis(2,4,6-trimethylphenyl)ethane-1,2-diimine-κ²N,N′]tetracarbonylchromium(0)

Marilé Landman,^a Roan Fraser,^a René Pretorius,^a Rohen Prinsloo,^a David C. Liles ^a and Petrus H. van Rooyen ^a ^*

^aDepartment of Chemistry, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
^*Correspondence e-mail: phvr@up.ac.za

(Received 16 May 2012; accepted 30 May 2012; online 16 June 2012)

The octahedral coordination of the Cr⁰ atom in the title compound, [Cr(C₂₀H₂₄N₂)(CO)₄], displays some distortion. This is manifested by an exocyclic torsion angle C(mesitylene)—N—Cr—C(carbonyl) that deviates by more than 20° from planarity. Another structural feature is the significant distortion from linearity of the Cr—C—O angles of the two carbonyl groups that interact with both ortho-methyl groups of the two mesitylene rings. The remaining two carbonyl groups overlap with the centres of the mesitylene rings themselves and are linear within <3°.

Related literature

For the synthesis of similar complexes, see: Baxter & Connor (1995 ). The MLCT (metal-to-ligand charge-transfer) band was observed at 570 nm for an analogous complex; see: Ruminski & Wallace (1987 ).

Experimental

Crystal data

[Cr(C₂₀H₂₄N₂)(CO)₄]
M_r = 456.45
Monoclinic, C c
a = 19.3119 (18) Å
b = 7.5303 (7) Å
c = 16.0769 (15) Å
β = 100.912 (2)°
V = 2295.7 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.53 mm⁻¹
T = 293 K
0.46 × 0.38 × 0.36 mm

Data collection

Adapted Bruker (Siemens) P4 diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.676, T_max = 0.826
5784 measured reflections
2708 independent reflections
2689 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.075
S = 1.07
2708 reflections
286 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.19 e Å⁻³
Absolute structure: Flack (1983 ), 652 Friedel pairs
Flack parameter: 0.018 (14)

Table 1
Selected geometric parameters (Å, °)

Cr1—C2	1.860 (3)
Cr1—C1	1.862 (2)
Cr1—C4	1.890 (3)
Cr1—C3	1.897 (3)
Cr1—N2	2.0740 (19)
Cr1—N1	2.0756 (18)

O1—C1—Cr1	177.1 (2)
O2—C2—Cr1	179.8 (3)
O3—C3—Cr1	172.0 (2)
O4—C4—Cr1	170.1 (3)

C1—Cr1—N2—C21	−21.80 (19)

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL and SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ), POV-RAY (Cason, 2004 ) and Mercury (Macrae et al., 2008 ); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812024786/wm2632sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812024786/wm2632Isup2.hkl

checkCIF report

Comment top

Cr(CO)₄(N,N'-dimesitylethylenediimine) or [Cr(CO)₄(C₂₀H₂₄N₂)], (I), was formed as a product in the microwave-assisted reaction of chromium hexacarbonyl with N,N'-(ethane-1,2-diylidene)bis(2,4,6-trimethylaniline) in dichloromethane as solvent. The intensely-coloured blue-black target complex was formed almost quantitatively with no side products. The complex was characterized using X-ray diffraction, NMR, IR and UV spectroscopy.

The synthesis of similar complexes, using disubstituted 2,2'-bipyridine compounds as coordinating ligands to study solvatochromism of these and other group 6 metal derivatives, was reported previously (Baxter & Connor, 1995). In the UV spectrum of (I), a stronger MLCT band is observed at 595 nm. The intense colour of the complex is ascribed to this metal-to-ligand transition. For an analogous complex, viz. [Cr(CO)₄(dpp)], dpp = 2,3-bis(2-pyridyl)pyrazine, the MLCT band was observed at 570 nm with CHCl₃ as solvent (Ruminski & Wallace, 1987). The transition around 300 nm was assigned as a dpp π* → π intraligand transition.

The solid state structure of the title compound revealed that the molecule packs with the mesitylene rings close to parallel to the (ac)-plane, with the angle between the mean planes formed by these rings at 19.81 (12)°. The 5-membered (Cr—N—C—C—N) ring is planar and approximately parallel to the (bc)-plane. This mean plane is almost perpendicular with the mean planes formed by the mesitylene rings, with the values for these angles being 85.42 (11)° and 76.87 (11)°. The distorted octahedral geometry around the Cr⁰ atom (Fig. 1) is manifested by the exocyclic torsion angle C21—N2—Cr1—C1 with a value of -21.81 (19)°. Another structural feature is the significant distortion from linearity, by 8.0° and 9.8°, of the Cr—C—O bond angles of the two carbonyl groups that interact with the ortho methyl groups of the two mesitylene rings. These two Cr—CO bond lengths are similar at 1.890 (3) Å (C4) and 1.897 (3) Å (C3), and the corresponding Cr—C—O bond angles are 170.2 (3)° and 172.0 (2)°. The remaining two carbonyl groups are positioned over the centre of the mesitylene rings and have little steric interaction, and are thus linear within 3°. This results in shorter Cr—C bond lengths of 1.861 (3) Å (C2) and 1.863 (3) Å (C1) with the corresponding Cr—C—O bond angles of 177.1 (2)° and 179.8 (3)°.

The crystal packing is without any other significant features, but the value of 18.5 Å³ per non-H atom is indicative of the efficient packing of the molecules in the unit cell.

Related literature top

For the synthesis of similar complexes, see: Baxter & Connor (1995). The MLCT (metal-to-ligand charge-transfer) band was observed at 570 nm for an analogous complex; see: Ruminski & Wallace (1987).

Experimental top

Cr(CO)₆ (3 mmol, 0.66 g) and N,N'-(ethane-1,2-diylidene)bis(2,4,6-trimethylaniline) (3 mmol, 0.60 g) were added to a microwave container and 30 ml of dichloromethane added. The container was sealed and the vessel inserted into the microwave oven. The reaction was left at 700 Watt for 1.5 h. The resulting solution was dark blue in colour. Solvent was removed in vacuo. The product was isolated on a silica gel column using 1:1 DCM:hexane as solvent. Recrystallization from the same solvent mixture yielded blue-black crystals. ¹H NMR (δ, p.p.m.), CDCl₃: 2.20 (s, 12H, o-Me), 2.33 (s, 6H, p-Me), 6.99 (s, 4H, m-H), 8.16 (s, 2H, N—H); ¹³C NMR (δ, p.p.m.), CDCl₃: 18.2, 20.8, 128.1, 129.3, 135.7, 151.4, 158.9, 213.6, 224.3. IR (νCO, cm^-1) KBr pellet: 2001(s), 1902(s), 1916(s), 1866(s). UV (λ, nm): 595, 362.

Structure description top

The crystal packing is without any other significant features, but the value of 18.5 Å³ per non-H atom is indicative of the efficient packing of the molecules in the unit cell.

For the synthesis of similar complexes, see: Baxter & Connor (1995). The MLCT (metal-to-ligand charge-transfer) band was observed at 570 nm for an analogous complex; see: Ruminski & Wallace (1987).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL and SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997), POV-RAY (Cason, 2004) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

Fig. 1. View of the asymmetric unit of (I). Displacement ellipsoids are shown at the 50% probability level.

[N,N'-Bis(2,4,6-trimethylphenyl)ethane-1,2-diimine- κ²N,N']tetracarbonylchromium(0) top

Crystal data top

[Cr(C₂₀H₂₄N₂)(CO)₄]	F(000) = 952
M_r = 456.45	D_x = 1.321 Mg m⁻³
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2yc	Cell parameters from 5595 reflections
a = 19.3119 (18) Å	θ = 2.7–26.4°
b = 7.5303 (7) Å	µ = 0.53 mm⁻¹
c = 16.0769 (15) Å	T = 293 K
β = 100.912 (2)°	Tetrahedron, dark-blue
V = 2295.7 (4) Å³	0.46 × 0.38 × 0.36 mm
Z = 4

Data collection top

Adapted Bruker (Siemens) P4 diffractometer	2708 independent reflections
Radiation source: fine-focus sealed tube	2689 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
Detector resolution: 8.3 pixels mm^-1	θ_max = 25.2°, θ_min = 2.6°
φ and ω scans	h = −23→15
Absorption correction: multi-scan (SADABS; Bruker, 2001)	k = −8→9
T_min = 0.676, T_max = 0.826	l = −18→15
5784 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.029	H-atom parameters constrained
wR(F²) = 0.075	w = 1/[σ²(F_o²) + (0.0589P)² + 0.0184P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max = 0.001
2708 reflections	Δρ_max = 0.19 e Å⁻³
286 parameters	Δρ_min = −0.19 e Å⁻³
2 restraints	Absolute structure: Flack (1983), 652 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.018 (14)

Crystal data top

[Cr(C₂₀H₂₄N₂)(CO)₄]	V = 2295.7 (4) Å³
M_r = 456.45	Z = 4
Monoclinic, Cc	Mo Kα radiation
a = 19.3119 (18) Å	µ = 0.53 mm⁻¹
b = 7.5303 (7) Å	T = 293 K
c = 16.0769 (15) Å	0.46 × 0.38 × 0.36 mm
β = 100.912 (2)°

Data collection top

Adapted Bruker (Siemens) P4 diffractometer	2708 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	2689 reflections with I > 2σ(I)
T_min = 0.676, T_max = 0.826	R_int = 0.021
5784 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	H-atom parameters constrained
wR(F²) = 0.075	Δρ_max = 0.19 e Å⁻³
S = 1.07	Δρ_min = −0.19 e Å⁻³
2708 reflections	Absolute structure: Flack (1983), 652 Friedel pairs
286 parameters	Absolute structure parameter: 0.018 (14)
2 restraints

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Cr1	0.212075 (18)	0.27015 (4)	0.64486 (2)	0.04182 (11)
C1	0.29172 (13)	0.1426 (3)	0.69481 (17)	0.0519 (5)
O1	0.34138 (11)	0.0624 (3)	0.72228 (16)	0.0767 (6)
C2	0.14826 (13)	0.0836 (3)	0.63989 (19)	0.0584 (6)
O2	0.10907 (13)	−0.0316 (3)	0.6367 (2)	0.0928 (8)
C3	0.19622 (13)	0.2895 (3)	0.75742 (17)	0.0515 (6)
O3	0.18859 (14)	0.2804 (3)	0.82656 (15)	0.0765 (6)
C4	0.23428 (19)	0.1662 (5)	0.54614 (19)	0.0731 (8)
O4	0.2498 (2)	0.0830 (5)	0.49413 (18)	0.1281 (13)
N1	0.13881 (10)	0.4434 (2)	0.57702 (11)	0.0453 (4)
N2	0.26563 (9)	0.5096 (2)	0.64851 (12)	0.0439 (4)
C5	0.16182 (12)	0.6007 (3)	0.56391 (16)	0.0529 (5)
H5	0.1345	0.6827	0.5289	0.063*
C6	0.23174 (13)	0.6397 (3)	0.60674 (16)	0.0520 (5)
H6	0.2517	0.7517	0.6048	0.062*
C11	0.06672 (11)	0.4040 (3)	0.53884 (13)	0.0440 (4)
C12	0.04958 (13)	0.3506 (3)	0.45416 (14)	0.0496 (5)
C13	−0.02004 (14)	0.3115 (4)	0.42077 (15)	0.0544 (5)
H13	−0.0319	0.2765	0.3644	0.065*
C14	−0.07296 (12)	0.3223 (4)	0.46827 (15)	0.0525 (5)
C15	−0.05452 (12)	0.3769 (4)	0.55176 (15)	0.0540 (5)
H15	−0.0894	0.3854	0.5843	0.065*
C16	0.01465 (12)	0.4195 (3)	0.58840 (13)	0.0484 (5)
C17	0.10406 (15)	0.3377 (5)	0.39831 (17)	0.0701 (7)
H17A	0.1275	0.2250	0.4070	0.105*
H17B	0.1380	0.4314	0.4124	0.105*
H17C	0.0813	0.3486	0.3400	0.105*
C18	−0.14839 (18)	0.2744 (5)	0.4295 (2)	0.0701 (8)
H18A	−0.1704	0.3727	0.3967	0.105*
H18B	−0.1739	0.2474	0.4737	0.105*
H18C	−0.1487	0.1726	0.3935	0.105*
C19	0.03138 (15)	0.4836 (5)	0.67837 (17)	0.0683 (8)
H19A	−0.0117	0.5040	0.6985	0.102*
H19B	0.0577	0.5923	0.6811	0.102*
H19C	0.0589	0.3955	0.7131	0.102*
C21	0.33116 (11)	0.5518 (3)	0.70416 (14)	0.0466 (5)
C22	0.39584 (13)	0.4965 (3)	0.68431 (18)	0.0540 (5)
C23	0.45673 (12)	0.5362 (4)	0.7433 (2)	0.0678 (7)
H23	0.5001	0.5020	0.7312	0.081*
C24	0.45589 (15)	0.6228 (4)	0.8178 (2)	0.0687 (7)
C25	0.39169 (15)	0.6775 (4)	0.83411 (19)	0.0634 (6)
H25	0.3905	0.7385	0.8841	0.076*
C26	0.32877 (13)	0.6448 (3)	0.77868 (16)	0.0539 (5)
C27	0.39987 (16)	0.4046 (5)	0.6026 (2)	0.0702 (8)
H27A	0.4453	0.4252	0.5885	0.105*
H27B	0.3639	0.4504	0.5583	0.105*
H27C	0.3930	0.2793	0.6087	0.105*
C28	0.5228 (2)	0.6584 (6)	0.8816 (3)	0.0993 (13)
H28A	0.5255	0.5782	0.9286	0.149*
H28B	0.5224	0.7785	0.9015	0.149*
H28C	0.5629	0.6410	0.8553	0.149*
C29	0.26070 (19)	0.7080 (4)	0.8015 (3)	0.0721 (8)
H29A	0.2231	0.6299	0.7770	0.108*
H29B	0.2506	0.8261	0.7801	0.108*
H29C	0.2651	0.7084	0.8620	0.108*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cr1	0.04006 (17)	0.03597 (17)	0.04822 (18)	0.00392 (16)	0.00531 (11)	0.00317 (16)
C1	0.0515 (12)	0.0419 (12)	0.0636 (13)	0.0048 (10)	0.0140 (10)	0.0105 (10)
O1	0.0578 (11)	0.0699 (13)	0.1017 (15)	0.0235 (10)	0.0131 (10)	0.0264 (12)
C2	0.0509 (13)	0.0436 (13)	0.0790 (16)	0.0050 (11)	0.0078 (11)	−0.0002 (11)
O2	0.0716 (14)	0.0568 (12)	0.151 (2)	−0.0180 (11)	0.0228 (14)	−0.0118 (14)
C3	0.0418 (11)	0.0514 (14)	0.0601 (16)	0.0053 (10)	0.0066 (10)	0.0071 (10)
O3	0.0736 (15)	0.1005 (17)	0.0578 (13)	0.0106 (11)	0.0187 (10)	0.0143 (10)
C4	0.094 (2)	0.0626 (17)	0.0631 (16)	0.0289 (16)	0.0159 (14)	0.0080 (13)
O4	0.201 (3)	0.114 (2)	0.0746 (15)	0.079 (2)	0.0382 (19)	−0.0077 (15)
N1	0.0472 (9)	0.0409 (9)	0.0457 (9)	0.0068 (7)	0.0033 (7)	0.0012 (7)
N2	0.0392 (8)	0.0408 (9)	0.0522 (9)	0.0017 (7)	0.0100 (7)	0.0032 (7)
C5	0.0520 (12)	0.0423 (12)	0.0605 (13)	0.0081 (9)	0.0007 (9)	0.0082 (9)
C6	0.0521 (12)	0.0385 (11)	0.0641 (13)	−0.0009 (9)	0.0075 (10)	0.0070 (10)
C11	0.0448 (11)	0.0395 (11)	0.0444 (10)	0.0074 (8)	−0.0002 (8)	0.0023 (8)
C12	0.0565 (12)	0.0492 (13)	0.0423 (10)	0.0042 (10)	0.0075 (9)	0.0019 (9)
C13	0.0577 (13)	0.0592 (12)	0.0415 (11)	0.0062 (12)	−0.0030 (9)	−0.0058 (10)
C14	0.0462 (12)	0.0503 (12)	0.0559 (13)	0.0070 (11)	−0.0029 (9)	−0.0019 (10)
C15	0.0446 (11)	0.0595 (13)	0.0559 (13)	0.0095 (10)	0.0047 (9)	−0.0060 (10)
C16	0.0471 (11)	0.0506 (13)	0.0444 (11)	0.0099 (9)	0.0010 (8)	−0.0047 (9)
C17	0.0644 (16)	0.099 (2)	0.0479 (13)	−0.0018 (16)	0.0138 (11)	−0.0036 (14)
C18	0.0518 (16)	0.080 (2)	0.0725 (18)	0.0039 (12)	−0.0041 (13)	−0.0128 (14)
C19	0.0547 (12)	0.094 (2)	0.0524 (13)	0.0149 (14)	0.0005 (10)	−0.0182 (13)
C21	0.0392 (10)	0.0421 (11)	0.0580 (12)	−0.0022 (8)	0.0078 (9)	0.0070 (9)
C22	0.0453 (11)	0.0480 (12)	0.0707 (14)	0.0018 (9)	0.0162 (10)	0.0114 (10)
C23	0.0383 (12)	0.0670 (16)	0.098 (2)	−0.0027 (11)	0.0126 (12)	0.0189 (15)
C24	0.0564 (14)	0.0599 (15)	0.0838 (19)	−0.0161 (12)	−0.0019 (12)	0.0153 (14)
C25	0.0675 (16)	0.0540 (13)	0.0657 (15)	−0.0134 (13)	0.0046 (12)	0.0007 (12)
C26	0.0506 (12)	0.0477 (13)	0.0640 (14)	−0.0078 (10)	0.0127 (10)	0.0000 (10)
C27	0.0645 (16)	0.0698 (18)	0.0823 (18)	0.0057 (14)	0.0293 (13)	0.0070 (15)
C28	0.0674 (19)	0.093 (3)	0.121 (3)	−0.0246 (19)	−0.0228 (19)	0.014 (2)
C29	0.0657 (17)	0.0710 (17)	0.085 (2)	−0.0084 (14)	0.0280 (15)	−0.0213 (15)

Geometric parameters (Å, º) top

Cr1—C2	1.860 (3)	C17—H17B	0.9600
Cr1—C1	1.862 (2)	C17—H17C	0.9600
Cr1—C4	1.890 (3)	C18—H18A	0.9600
Cr1—C3	1.897 (3)	C18—H18B	0.9600
Cr1—N2	2.0740 (19)	C18—H18C	0.9600
Cr1—N1	2.0756 (18)	C19—H19A	0.9600
C1—O1	1.148 (3)	C19—H19B	0.9600
C2—O2	1.146 (3)	C19—H19C	0.9600
C3—O3	1.151 (4)	C21—C26	1.396 (3)
C4—O4	1.130 (4)	C21—C22	1.409 (3)
N1—C5	1.296 (3)	C22—C23	1.396 (4)
N1—C11	1.442 (3)	C22—C27	1.500 (4)
N2—C6	1.294 (3)	C23—C24	1.368 (5)
N2—C21	1.440 (3)	C23—H23	0.9300
C5—C6	1.425 (3)	C24—C25	1.378 (4)
C5—H5	0.9300	C24—C28	1.514 (4)
C6—H6	0.9300	C25—C26	1.386 (4)
C11—C12	1.398 (3)	C25—H25	0.9300
C11—C16	1.401 (3)	C26—C29	1.507 (4)
C12—C13	1.382 (4)	C27—H27A	0.9600
C12—C17	1.510 (3)	C27—H27B	0.9600
C13—C14	1.389 (4)	C27—H27C	0.9600
C13—H13	0.9300	C28—H28A	0.9600
C14—C15	1.384 (3)	C28—H28B	0.9600
C14—C18	1.516 (4)	C28—H28C	0.9600
C15—C16	1.391 (3)	C29—H29A	0.9600
C15—H15	0.9300	C29—H29B	0.9600
C16—C19	1.501 (3)	C29—H29C	0.9600
C17—H17A	0.9600

C2—Cr1—C1	96.63 (12)	C12—C17—H17C	109.5
C2—Cr1—C4	84.56 (15)	H17A—C17—H17C	109.5
C1—Cr1—C4	81.28 (13)	H17B—C17—H17C	109.5
C2—Cr1—C3	82.74 (12)	C14—C18—H18A	109.5
C1—Cr1—C3	84.11 (11)	C14—C18—H18B	109.5
C4—Cr1—C3	159.37 (13)	H18A—C18—H18B	109.5
C2—Cr1—N2	168.64 (9)	C14—C18—H18C	109.5
C1—Cr1—N2	93.98 (9)	H18A—C18—H18C	109.5
C4—Cr1—N2	101.09 (13)	H18B—C18—H18C	109.5
C3—Cr1—N2	94.36 (10)	C16—C19—H19A	109.5
C2—Cr1—N1	94.11 (9)	C16—C19—H19B	109.5
C1—Cr1—N1	167.48 (9)	H19A—C19—H19B	109.5
C4—Cr1—N1	93.40 (10)	C16—C19—H19C	109.5
C3—Cr1—N1	103.65 (9)	H19A—C19—H19C	109.5
N2—Cr1—N1	75.83 (7)	H19B—C19—H19C	109.5
O1—C1—Cr1	177.1 (2)	C26—C21—C22	121.1 (2)
O2—C2—Cr1	179.8 (3)	C26—C21—N2	118.43 (19)
O3—C3—Cr1	172.0 (2)	C22—C21—N2	120.4 (2)
O4—C4—Cr1	170.1 (3)	C23—C22—C21	116.9 (3)
C5—N1—C11	116.85 (18)	C23—C22—C27	121.1 (2)
C5—N1—Cr1	116.04 (15)	C21—C22—C27	122.0 (2)
C11—N1—Cr1	126.99 (14)	C24—C23—C22	123.3 (2)
C6—N2—C21	117.0 (2)	C24—C23—H23	118.4
C6—N2—Cr1	116.32 (16)	C22—C23—H23	118.4
C21—N2—Cr1	125.75 (14)	C23—C24—C25	118.0 (3)
N1—C5—C6	115.6 (2)	C23—C24—C28	121.9 (3)
N1—C5—H5	122.2	C25—C24—C28	120.1 (3)
C6—C5—H5	122.2	C24—C25—C26	122.4 (3)
N2—C6—C5	115.7 (2)	C24—C25—H25	118.8
N2—C6—H6	122.1	C26—C25—H25	118.8
C5—C6—H6	122.1	C25—C26—C21	118.3 (2)
C12—C11—C16	120.98 (19)	C25—C26—C29	119.1 (3)
C12—C11—N1	120.35 (19)	C21—C26—C29	122.6 (2)
C16—C11—N1	118.67 (18)	C22—C27—H27A	109.5
C13—C12—C11	118.2 (2)	C22—C27—H27B	109.5
C13—C12—C17	119.4 (2)	H27A—C27—H27B	109.5
C11—C12—C17	122.3 (2)	C22—C27—H27C	109.5
C12—C13—C14	122.5 (2)	H27A—C27—H27C	109.5
C12—C13—H13	118.8	H27B—C27—H27C	109.5
C14—C13—H13	118.8	C24—C28—H28A	109.5
C15—C14—C13	118.0 (2)	C24—C28—H28B	109.5
C15—C14—C18	121.4 (2)	H28A—C28—H28B	109.5
C13—C14—C18	120.6 (2)	C24—C28—H28C	109.5
C14—C15—C16	121.9 (2)	H28A—C28—H28C	109.5
C14—C15—H15	119.0	H28B—C28—H28C	109.5
C16—C15—H15	119.0	C26—C29—H29A	109.5
C15—C16—C11	118.35 (19)	C26—C29—H29B	109.5
C15—C16—C19	119.8 (2)	H29A—C29—H29B	109.5
C11—C16—C19	121.9 (2)	C26—C29—H29C	109.5
C12—C17—H17A	109.5	H29A—C29—H29C	109.5
C12—C17—H17B	109.5	H29B—C29—H29C	109.5
H17A—C17—H17B	109.5

C2—Cr1—N1—C5	−179.67 (19)	C11—C12—C13—C14	−0.4 (4)
C1—Cr1—N1—C5	−30.5 (6)	C17—C12—C13—C14	−179.3 (3)
C4—Cr1—N1—C5	−94.9 (2)	C12—C13—C14—C15	0.9 (4)
C3—Cr1—N1—C5	96.82 (18)	C12—C13—C14—C18	−178.7 (3)
N2—Cr1—N1—C5	5.70 (17)	C13—C14—C15—C16	−0.3 (4)
C2—Cr1—N1—C11	−3.74 (19)	C18—C14—C15—C16	179.3 (3)
C1—Cr1—N1—C11	145.4 (5)	C14—C15—C16—C11	−0.8 (4)
C4—Cr1—N1—C11	81.0 (2)	C14—C15—C16—C19	178.0 (3)
C3—Cr1—N1—C11	−87.25 (18)	C12—C11—C16—C15	1.3 (4)
N2—Cr1—N1—C11	−178.36 (18)	N1—C11—C16—C15	−178.4 (2)
C2—Cr1—N2—C6	−31.3 (6)	C12—C11—C16—C19	−177.5 (2)
C1—Cr1—N2—C6	169.63 (18)	N1—C11—C16—C19	2.8 (4)
C4—Cr1—N2—C6	87.7 (2)	C6—N2—C21—C26	71.7 (3)
C3—Cr1—N2—C6	−105.99 (18)	Cr1—N2—C21—C26	−96.8 (2)
N1—Cr1—N2—C6	−3.00 (17)	C6—N2—C21—C22	−109.7 (3)
C2—Cr1—N2—C21	137.3 (5)	Cr1—N2—C21—C22	81.8 (2)
C1—Cr1—N2—C21	−21.80 (19)	C26—C21—C22—C23	1.2 (4)
C4—Cr1—N2—C21	−103.68 (19)	N2—C21—C22—C23	−177.4 (2)
C3—Cr1—N2—C21	62.59 (18)	C26—C21—C22—C27	−176.9 (2)
N1—Cr1—N2—C21	165.58 (18)	N2—C21—C22—C27	4.6 (4)
C11—N1—C5—C6	176.19 (19)	C21—C22—C23—C24	0.6 (4)
Cr1—N1—C5—C6	−7.5 (3)	C27—C22—C23—C24	178.7 (3)
C21—N2—C6—C5	−169.4 (2)	C22—C23—C24—C25	−1.8 (4)
Cr1—N2—C6—C5	0.2 (3)	C22—C23—C24—C28	178.0 (3)
N1—C5—C6—N2	4.8 (3)	C23—C24—C25—C26	1.2 (4)
C5—N1—C11—C12	82.6 (3)	C28—C24—C25—C26	−178.6 (3)
Cr1—N1—C11—C12	−93.3 (2)	C24—C25—C26—C21	0.5 (4)
C5—N1—C11—C16	−97.7 (2)	C24—C25—C26—C29	179.6 (3)
Cr1—N1—C11—C16	86.4 (2)	C22—C21—C26—C25	−1.7 (4)
C16—C11—C12—C13	−0.7 (4)	N2—C21—C26—C25	176.8 (2)
N1—C11—C12—C13	178.9 (2)	C22—C21—C26—C29	179.2 (3)
C16—C11—C12—C17	178.2 (3)	N2—C21—C26—C29	−2.2 (4)
N1—C11—C12—C17	−2.2 (4)

Experimental details

Crystal data
Chemical formula	[Cr(C₂₀H₂₄N₂)(CO)₄]
M_r	456.45
Crystal system, space group	Monoclinic, Cc
Temperature (K)	293
a, b, c (Å)	19.3119 (18), 7.5303 (7), 16.0769 (15)
β (°)	100.912 (2)
V (Å³)	2295.7 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.53
Crystal size (mm)	0.46 × 0.38 × 0.36

Data collection
Diffractometer	Adapted Bruker (Siemens) P4
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.676, 0.826
No. of measured, independent and observed [I > 2σ(I)] reflections	5784, 2708, 2689
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.600

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.075, 1.07
No. of reflections	2708
No. of parameters	286
No. of restraints	2
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.19
Absolute structure	Flack (1983), 652 Friedel pairs
Absolute structure parameter	0.018 (14)

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008), SHELXTL and SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), POV-RAY (Cason, 2004) and Mercury (Macrae et al., 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Selected geometric parameters (Å, º) top

Cr1—C2	1.860 (3)	Cr1—C3	1.897 (3)
Cr1—C1	1.862 (2)	Cr1—N2	2.0740 (19)
Cr1—C4	1.890 (3)	Cr1—N1	2.0756 (18)

O1—C1—Cr1	177.1 (2)	O3—C3—Cr1	172.0 (2)
O2—C2—Cr1	179.8 (3)	O4—C4—Cr1	170.1 (3)

C1—Cr1—N2—C21	−21.80 (19)

Acknowledgements

Funding received for this work from the University of Pretoria and the Oppenheimer Memorial Fund is acknowledged.

References

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