Tris­(tert-butyl­iso­nitrile)­hexa­carbonyl-μ₃-ethyl­idyne-triangulo-tricobalt(I)(3 Co—Co)

The title molecule, [Co₃(C₂H₃)(C₅H₉N)₃(CO)₆] or [Co₃(μ₃-CCH₃)(CN^tBu)₃(CO)₆], lies on a threefold rotation axis. The three isonitrile ligands each occupy an equatorial site on each of the three Co atoms. The average Co—Co bond length is 2.4769 (6) Å. The tert-butyl groups are disordered over two orientations, with site occupancies of ca 0.6:0.4.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.007 Å
• Disorder in main residue
• R factor = 0.025
• wR factor = 0.059
• Data-to-parameter ratio = 14.9

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT242_ALERT_2_A Check Low       Ueq as Compared to Neighbors for         C4

Author Response: Associated with the disorder of the butyl group, C4 is not disordered, attached Me groups are.

Alert level B
PLAT220_ALERT_2_B Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       3.74 Ratio

Alert level C
PLAT301_ALERT_3_C Main Residue  Disorder .........................      20.00 Perc.
PLAT320_ALERT_2_C Check Hybridisation of  C1     in Main Residue .          ?
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          7

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.38
           From the CIF: _reflns_number_total               1991
           Count of symmetry unique reflns         1002
           Completeness (_total/calc)            198.70%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       989
           Fraction of Friedel pairs measured     0.987
           Are heavy atom types Z>Si present        yes
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   1 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

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

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S1. Comment

The title compound is the first structurally characterized isonitrile derivative of a [Co₃(µ₃-CR)(CO)₉] cluster. The three CNBu^t ligands have displaced three equatorial CO ligands in the parent molecule, to give a molecule with C₃ symmetry. The substitution has had little effect on the parameters of the cluster core with average Co—Co and Co—C distances (2.4769 (6) and 1.908 (3) Å respectively) that do not differ significantly from those of parent (2.467 (7) and 1.90 (2) Å, (Sutton & Dahl, 1967) though the low precision of the earlier study would mask any small changes.

Related literature

For details of the synthesis, see Newman & Manning (1974). For the structure of the parent nonacarbonyl cluster, see Sutton & Dahl (1967). Other examples of equatorially trisubstituted derivatives of [Co₃(µ₃-CR)(CO)₉] include the (MeO)₃P derivative (Dawson et al., 1979). Axial substitution appears to be favoured only by very bulky or chelating ligands (D'Agostino et al., 1991; Renouard et al., 1996).

S2. Experimental

The compound was prepared by thermal reaction between [Co₃(µ₃-CR)(CO)₉] and CNBu^t (Newman & Manning, 1974). X-ray crystals were grown from pentane.

S3. Refinement

The tert-butyl groups are disordered over two orientations which refined to a 0.64:0.36 occupancy ratio; this accounts for the large differences between the displacement parameters of the C4 carbon atom and the attached CH₃ carbon atoms. All H-atoms were positioned geometrically and refined using a riding model with d(C—H) = 0.96 Å, U_iso = 1.5U_eq (C).

Computing details

Data collection: SMART (Bruker 2001); cell refinement: SAINT (Bruker 2001); data reduction: SAINT (Bruker 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Version 1.70.01; Farrugia, 1999).

Figures

	Fig. 1. Structure of [Co3(µ3-CCH3)(CO)6(CNBu^t)3] with diplacement parameters drawn at the 30% probability level. Only the major disorder component of the t-butyl group is shown.
	Fig. 2. A view down the threefold axis. Only the major disorder component of the t-butyl group is shown.

tris(tert-butylisonitrile)hexacarbonyl-µ₃-ethylidyne- triangulo-tricobalt(I)(3 Co—Co)

Crystal data

[Co3(C2H3)(C5H9N)3(CO)6]	Dx = 1.420 Mg m^−3
Mr = 621.29	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 5750 reflections
Hall symbol: R 3 -2"c	θ = 2.4–26.4°
a = 16.9804 (6) Å	µ = 1.73 mm^−1
c = 17.4605 (11) Å	T = 293 K
V = 4360.0 (4) Å^3	Hexagonal rod, black
Z = 6	0.54 × 0.13 × 0.11 mm
F(000) = 1908

Data collection

Siemens SMART CCD diffractometer	1991 independent reflections
Radiation source: fine-focus sealed tube	1757 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
multi–scan	θmax = 26.4°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −21→20
Tmin = 0.672, Tmax = 0.830	k = −21→21
10767 measured reflections	l = −21→21

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.025	H-atom parameters constrained
wR(F^2) = 0.059	w = 1/[σ^2(Fo^2) + (0.0388P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max = 0.002
1991 reflections	Δρmax = 0.21 e Å^−3
134 parameters	Δρmin = −0.16 e Å^−3
1 restraint	Absolute structure: Flack (1983), with 989 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.01 (2)

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Co1	0.92643 (2)	0.01828 (2)	0.164850 (14)	0.04289 (10)
N1	0.91952 (19)	0.17320 (19)	0.24181 (17)	0.0676 (7)
C1	1.0000	0.0000	0.2372 (3)	0.0441 (9)
C2	1.0000	0.0000	0.3218 (3)	0.0698 (14)
H2A	1.0116	0.0581	0.3401	0.105*	0.333
H2B	1.0466	−0.0116	0.3401	0.105*	0.333
H2C	0.9419	−0.0466	0.3401	0.105*	0.333
C3	0.92327 (19)	0.1150 (2)	0.21234 (18)	0.0557 (7)
C4	0.9179 (2)	0.2509 (2)	0.27631 (19)	0.0684 (9)
C11	0.9168 (2)	0.0388 (2)	0.06419 (19)	0.0593 (7)
O11	0.9109 (2)	0.0514 (2)	0.00155 (15)	0.0992 (9)
C12	0.8144 (2)	−0.0659 (2)	0.18837 (19)	0.0618 (8)
O12	0.74179 (17)	−0.1194 (2)	0.2037 (2)	0.1022 (10)
C5	0.9649 (10)	0.3290 (5)	0.2265 (6)	0.120 (5)	0.640 (16)
H51	0.9328	0.3171	0.1788	0.180*	0.640 (16)
H52	1.0255	0.3405	0.2172	0.180*	0.640 (16)
H53	0.9676	0.3812	0.2506	0.180*	0.640 (16)
C6	0.9631 (13)	0.2680 (9)	0.3533 (7)	0.166 (8)	0.640 (16)
H61	0.9298	0.2155	0.3853	0.249*	0.640 (16)
H62	0.9643	0.3197	0.3768	0.249*	0.640 (16)
H63	1.0243	0.2797	0.3470	0.249*	0.640 (16)
C7	0.8180 (6)	0.2243 (6)	0.2791 (9)	0.135 (6)	0.640 (16)
H71	0.7858	0.1729	0.3124	0.202*	0.640 (16)
H72	0.7926	0.2086	0.2285	0.202*	0.640 (16)
H73	0.8126	0.2745	0.2980	0.202*	0.640 (16)
C5A	1.0165 (10)	0.3310 (10)	0.2776 (15)	0.126 (10)	0.360 (16)
H51A	1.0400	0.3441	0.2263	0.188*	0.360 (16)
H52A	1.0533	0.3150	0.3083	0.188*	0.360 (16)
H53A	1.0176	0.3836	0.2989	0.188*	0.360 (16)
C6A	0.8664 (11)	0.2787 (10)	0.2206 (10)	0.100 (7)	0.360 (16)
H61A	0.8968	0.2940	0.1719	0.150*	0.360 (16)
H62A	0.8646	0.3304	0.2407	0.150*	0.360 (16)
H63A	0.8054	0.2290	0.2142	0.150*	0.360 (16)
C7A	0.875 (2)	0.2261 (16)	0.3488 (9)	0.154 (13)	0.360 (16)
H71A	0.9097	0.2094	0.3820	0.231*	0.360 (16)
H72A	0.8149	0.1754	0.3432	0.231*	0.360 (16)
H73A	0.8727	0.2766	0.3706	0.231*	0.360 (16)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.03864 (19)	0.04002 (19)	0.05232 (16)	0.02140 (15)	−0.00286 (15)	−0.00329 (17)
N1	0.0639 (16)	0.0525 (15)	0.0928 (18)	0.0338 (14)	−0.0040 (15)	−0.0173 (14)
C1	0.0416 (13)	0.0416 (13)	0.049 (2)	0.0208 (7)	0.000	0.000
C2	0.077 (2)	0.077 (2)	0.055 (3)	0.0386 (11)	0.000	0.000
C3	0.0456 (15)	0.0494 (16)	0.0751 (18)	0.0259 (14)	−0.0041 (13)	−0.0059 (14)
C4	0.078 (2)	0.0545 (18)	0.081 (2)	0.0398 (18)	−0.0010 (18)	−0.0181 (16)
C11	0.0538 (18)	0.0548 (17)	0.067 (2)	0.0257 (14)	−0.0064 (14)	0.0037 (14)
O11	0.105 (2)	0.111 (2)	0.0676 (16)	0.0438 (19)	−0.0143 (14)	0.0177 (15)
C12	0.0504 (19)	0.0576 (18)	0.083 (2)	0.0312 (16)	0.0002 (15)	0.0059 (14)
O12	0.0457 (14)	0.0793 (18)	0.171 (3)	0.0234 (13)	0.0190 (16)	0.0303 (18)
C5	0.169 (15)	0.064 (5)	0.121 (6)	0.054 (7)	0.021 (7)	0.002 (4)
C6	0.29 (2)	0.143 (12)	0.095 (7)	0.132 (15)	−0.076 (12)	−0.049 (8)
C7	0.096 (6)	0.085 (6)	0.237 (18)	0.056 (5)	0.031 (7)	−0.024 (8)
C5A	0.087 (9)	0.075 (9)	0.21 (3)	0.038 (7)	−0.026 (10)	−0.075 (13)
C6A	0.104 (14)	0.079 (11)	0.141 (12)	0.063 (12)	−0.024 (10)	−0.024 (9)
C7A	0.31 (4)	0.132 (16)	0.074 (13)	0.15 (2)	0.067 (19)	0.015 (11)

Geometric parameters (Å, º)

Co1—C12	1.764 (3)	C5—H51	0.9600
Co1—C11	1.815 (3)	C5—H52	0.9600
Co1—C3	1.865 (3)	C5—H53	0.9600
Co1—C1	1.908 (3)	C6—H61	0.9600
Co1—Co1^i	2.4769 (6)	C6—H62	0.9600
N1—C3	1.143 (4)	C6—H63	0.9600
N1—C4	1.464 (4)	C7—H71	0.9600
C1—C2	1.477 (8)	C7—H72	0.9600
C2—H2A	0.9600	C7—H73	0.9600
C2—H2B	0.9600	C5A—H51A	0.9600
C2—H2C	0.9600	C5A—H52A	0.9600
C4—C7A	1.413 (16)	C5A—H53A	0.9600
C4—C5	1.446 (8)	C6A—H61A	0.9600
C4—C6	1.503 (10)	C6A—H62A	0.9600
C4—C7	1.522 (9)	C6A—H63A	0.9600
C4—C6A	1.532 (14)	C7A—H71A	0.9600
C4—C5A	1.541 (14)	C7A—H72A	0.9600
C11—O11	1.129 (4)	C7A—H73A	0.9600
C12—O12	1.139 (4)
C12—Co1—C11	102.54 (15)	O12—C12—Co1	179.1 (3)
C12—Co1—C3	96.66 (13)	C4—C5—H51	109.5
C11—Co1—C3	102.54 (14)	C4—C5—H52	109.5
C12—Co1—C1	104.04 (11)	H51—C5—H52	109.5
C11—Co1—C1	143.23 (15)	C4—C5—H53	109.5
C3—Co1—C1	99.12 (12)	H51—C5—H53	109.5
C12—Co1—Co1^i	150.03 (10)	H52—C5—H53	109.5
C11—Co1—Co1^i	96.93 (10)	C4—C6—H61	109.5
C3—Co1—Co1^i	101.12 (9)	C4—C6—H62	109.5
C1—Co1—Co1^i	49.53 (8)	H61—C6—H62	109.5
C12—Co1—Co1^ii	92.89 (10)	C4—C6—H63	109.5
C11—Co1—Co1^ii	104.41 (11)	H61—C6—H63	109.5
C3—Co1—Co1^ii	148.64 (9)	H62—C6—H63	109.5
Co1^i—Co1—Co1^ii	60.0	C4—C7—H71	109.5
C3—N1—C4	176.9 (4)	C4—C7—H72	109.5
C2—C1—Co1	131.45 (10)	H71—C7—H72	109.5
Co1^ii—C1—Co1	80.95 (16)	C4—C7—H73	109.5
C1—C2—H2A	109.5	H71—C7—H73	109.5
C1—C2—H2B	109.5	H72—C7—H73	109.5
H2A—C2—H2B	109.5	C4—C5A—H51A	109.5
C1—C2—H2C	109.5	C4—C5A—H52A	109.5
H2A—C2—H2C	109.5	H51A—C5A—H52A	109.5
H2B—C2—H2C	109.5	C4—C5A—H53A	109.5
N1—C3—Co1	178.6 (3)	H51A—C5A—H53A	109.5
C7A—C4—N1	109.7 (8)	H52A—C5A—H53A	109.5
C5—C4—N1	109.2 (4)	C4—C6A—H61A	109.5
C5—C4—C6	111.5 (7)	C4—C6A—H62A	109.5
N1—C4—C6	107.7 (6)	H61A—C6A—H62A	109.5
C5—C4—C7	108.3 (8)	C4—C6A—H63A	109.5
N1—C4—C7	105.4 (4)	H61A—C6A—H63A	109.5
C6—C4—C7	114.5 (9)	H62A—C6A—H63A	109.5
C7A—C4—C6A	112.1 (14)	C4—C7A—H71A	109.5
N1—C4—C6A	106.7 (5)	C4—C7A—H72A	109.5
C7A—C4—C5A	114.7 (15)	H71A—C7A—H72A	109.5
N1—C4—C5A	107.4 (5)	C4—C7A—H73A	109.5
C6A—C4—C5A	105.9 (11)	H71A—C7A—H73A	109.5
O11—C11—Co1	179.9 (4)	H72A—C7A—H73A	109.5

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