metal-organic compounds
[μ-3,3′-Diisopropyl-1,1′-(propane-1,3-diyl)bis(1,3-diazinan-2-ylidene)]bis[bromido(η4-cycloocta-1,5-diene)rhodium(I)]
aInstitut für Polymerchemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and bInstitut für Allgemeine Anorganische und Theoretische Chemie, Universität Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
*Correspondence e-mail: michael.buchmeiser@ipoc.uni-stuttgart.de
The title compound, [Rh2Br2(C8H12)2(C17H32N4)], was obtained by the reaction of 3,3′-(propane-1,3-diyl)bis(1-isopropyl-3,4,5,6-tetrahydropyrimidin-1-ium) bromide and [{Rh(cod)Cl}2] (cod is cycloocta-1,5-diene) in tetrahydrofuran. The two RhI atoms each have a distorted square-planar coordination environment, defined by a bidentate cod ligand, a bromide anion and one C atom of the bridging bidentate bis-N-heterocyclcic carbene (NHC) ligand. The average Rh—CNHC distance is 2.038 (7) Å, suggesting that the bond has a major σ contribution with very little back donation. The distances between the cod ligands and the RhI atoms vary between 2.104 (4) and 2.210 (4) Å.
CCDC reference: 981713
Related literature
For general background on the development of N-heterocyclic (NHC) as replacements for in the area of organometallic catalysis and Rh–NHC-based complexes, see: Herrmann et al. (1996, 1997); Mayr et al. (2004); Díez-González et al. (2009). For examples of the application of RhI complexes as catalysts in hydroformylation reactions, see: Evans et al. (1968); Reindl et al. (2013). For the synthesis of homobimetallic RhI–NHC complexes and their application as catalysts in hydrosilylations, see: Huckaba et al. (2013).
Experimental
Crystal data
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Data collection: COLLECT (Nonius, 1998); cell DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and publCIF (Westrip, 2010).
Supporting information
CCDC reference: 981713
10.1107/S1600536814001135/im2446sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814001135/im2446Isup2.hkl
[{Rh(cod)Cl}2] (200 mg, 0.47 mmol) was dissolved in anhydrous THF (5 ml), and lithium tert-butoxide (91 mg, 1.14 mmol) was added under vigorous stirring. The mixture was stirred for another 30 min at room temperature, then 3,3'-(propane-1,3-diyl)bis(1-isopropyl-3,4,5,6-tetrahydropyrimidin-1-ium)bromide (220 mg, 0.49 mmol) was added. The reaction mixture was stirred overnight at 65°C, after this time TLC showed no further conversion. The solvent was removed in vacuo and the product was purified by
(silica gel) using dichloromethane:ethanol (250:4) as the mobile phase. The product eluted as a yellow band in the second fraction. The product fractions were pooled and evaporated to dryness to yield a yellow solid (230 mg, 56%). Yellow crystals suitable for X-ray analysis were obtained by layering pentane over a of the title compound in CH2Cl2 at -30°C.All hydrogen positions could be localised, but were only refined regularly with bond restraints of 93 pm at the double bonds of cyclooctadiene (C1, C2, C5, C6, C9, C10, C13 and C14). All other hydrogens were calculated by geometrical methods and refined as a riding model with temperature factors Ueq 1.2 or 1.5 (methyl groups) times higher than their linked carbon atoms.
The hydroformylation reaction is one of the most important catalytic reactions at an industrial level that can be employed for the conversion of σ donation and the excellent stability, have been widely applied as an ideal replacement for in the area of organometallic catalysis (Díez-González et al., 2009). Within that context, homobimetallic rhodium(I) NHC complexes have been reported to represent versatile catalysts for the hydrosilylation of e.g. and tertiary (Huckaba et al., 2013). The title compound was prepared by the reaction of 3,3'- (propane-1,3-diyl)bis(1-isopropyl-3,4,5,6-tetrahydropyrimidin-1-ium) bromide and [{Rh(cod)Cl}2] in anhydrous THF. It crystallizes in the Pbca (No.61). The structure exhibits a typical pesudo-square planar ligand environment for the Rh(I) centers which are coordinated by a bidentate cycloocta-1,5-diene (cod) ligand, one carbon atom of the bridging bis-N-heterocyclic carbene ligand and one bromide atom. The molecular structure is closely similar to that of the recently reported compounds bromo(η4-1,5-cyclooctadiene){1,3-bis(2-propyl)-3,4,5,6- tetrahydropyrimidin- 2-ylidene}rhodium and bromo(η4-1,5-cyclooctadiene){1,3-dimesityl-3,4,5,6- tetrahydropyrimidin- 2-ylidene}rhodium (Mayr et al., 2004).
carbon monoxide and hydrogen into and Most of the hydroformylation catalysts so far were based on rhodium and phosphine ligands (e.g., the Wilkinson-catalyst [RhCl(PPh3)3] (Evans et al., 1968). However, phosphine ligands have some common disadvantages as they are easily oxidized by molecular oxygen in solution. Furthermore, and CO show similar binding constants to rhodium. Due to the fact that CO-pressures applied during hydroformylation are quite high, an excess of phosphine is required to generate a sterically demanding environment around the active rhodium-center, a prerequisite for high n/iso-ratios. N-heterocyclic (NHCs), owing to their strongFor general background on the development of N-heterocyclic
(NHC) as replacements for in the area of organometallic catalysis and Rh–NHC-based complexes, see: Herrmann et al. (1996, 1997); Mayr et al. (2004); Díez-González et al. (2009). For examples of the application of RhI complexes as catalysts in hydroformylation reactions, see: Evans et al. (1968); Reindl et al. (2013). For the synthesis of homobimetallic rhodium(I) NHC complexes and their application as catalysts in hydrosilylations, see: Huckaba et al. (2013).Data collection: COLLECT (Nonius, 1998); cell
DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010).Fig. 1. Molecular structure of the title molecule with displacement ellipsoids drawn at the 30% probability level. |
[Rh2Br2(C8H12)2(C17H32N4)] | F(000) = 3536 |
Mr = 874.46 | Dx = 1.653 Mg m−3 |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 54150 reflections |
a = 16.4075 (2) Å | θ = 1.0–25.0° |
b = 15.7975 (3) Å | µ = 3.24 mm−1 |
c = 27.1065 (4) Å | T = 233 K |
V = 7025.94 (19) Å3 | Prism, yellow |
Z = 8 | 0.2 × 0.1 × 0.08 mm |
Nonius KappaCCD diffractometer | 6186 independent reflections |
Radiation source: fine-focus sealed tube | 5045 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.083 |
Detector resolution: 9.1 pixels mm-1 | θmax = 25.0°, θmin = 1.9° |
phi and ω scans | h = −19→19 |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | k = −18→18 |
Tmin = 0.432, Tmax = 0.755 | l = −32→32 |
57878 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.033 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.078 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0254P)2 + 11.9446P] where P = (Fo2 + 2Fc2)/3 |
6186 reflections | (Δ/σ)max = 0.002 |
402 parameters | Δρmax = 0.95 e Å−3 |
8 restraints | Δρmin = −0.51 e Å−3 |
[Rh2Br2(C8H12)2(C17H32N4)] | V = 7025.94 (19) Å3 |
Mr = 874.46 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 16.4075 (2) Å | µ = 3.24 mm−1 |
b = 15.7975 (3) Å | T = 233 K |
c = 27.1065 (4) Å | 0.2 × 0.1 × 0.08 mm |
Nonius KappaCCD diffractometer | 6186 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | 5045 reflections with I > 2σ(I) |
Tmin = 0.432, Tmax = 0.755 | Rint = 0.083 |
57878 measured reflections |
R[F2 > 2σ(F2)] = 0.033 | 8 restraints |
wR(F2) = 0.078 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0254P)2 + 11.9446P] where P = (Fo2 + 2Fc2)/3 |
6186 reflections | Δρmax = 0.95 e Å−3 |
402 parameters | Δρmin = −0.51 e Å−3 |
Experimental. Absorption correction: multi-scan from symmetry-related measurements |
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. Hydrogen atoms at C=C bonds of COD were refined with bond restraints (d=0.93 angs.) for C1, C2, C5, C6, C9, C10, C13 and C14 |
x | y | z | Uiso*/Ueq | ||
Rh1 | 0.311925 (16) | 0.057582 (18) | 0.871181 (10) | 0.02707 (9) | |
Rh2 | 0.322674 (16) | 0.166937 (18) | 0.624003 (10) | 0.02634 (9) | |
Br1 | 0.21591 (3) | 0.18233 (3) | 0.873742 (16) | 0.04127 (12) | |
Br2 | 0.23333 (3) | 0.03852 (3) | 0.613041 (18) | 0.04847 (13) | |
N1 | 0.17169 (18) | −0.06234 (19) | 0.87524 (11) | 0.0312 (7) | |
N4 | 0.17595 (18) | 0.2779 (2) | 0.61382 (11) | 0.0316 (7) | |
N2 | 0.20658 (19) | −0.0214 (2) | 0.79627 (11) | 0.0340 (8) | |
N3 | 0.20629 (18) | 0.2398 (2) | 0.69400 (11) | 0.0319 (7) | |
C1 | 0.3988 (3) | −0.0285 (3) | 0.84394 (18) | 0.0462 (11) | |
H1 | 0.376 (2) | −0.064 (2) | 0.8205 (12) | 0.050 (13)* | |
C2 | 0.3797 (3) | −0.0498 (3) | 0.89246 (18) | 0.0455 (11) | |
H2 | 0.3421 (19) | −0.090 (2) | 0.9001 (15) | 0.041 (12)* | |
C3 | 0.4344 (4) | −0.0301 (4) | 0.9360 (2) | 0.0796 (18) | |
H3A | 0.4201 | −0.0690 | 0.9628 | 0.096* | |
H3B | 0.4907 | −0.0426 | 0.9264 | 0.096* | |
C4 | 0.4320 (4) | 0.0559 (4) | 0.9555 (2) | 0.0792 (18) | |
H4A | 0.4876 | 0.0729 | 0.9641 | 0.095* | |
H4B | 0.4000 | 0.0556 | 0.9861 | 0.095* | |
C5 | 0.3968 (3) | 0.1214 (3) | 0.92170 (19) | 0.0485 (12) | |
H5 | 0.361 (2) | 0.158 (2) | 0.9372 (15) | 0.059 (15)* | |
C6 | 0.4213 (3) | 0.1385 (3) | 0.8752 (2) | 0.0508 (12) | |
H6 | 0.401 (2) | 0.1895 (15) | 0.8629 (12) | 0.025 (9)* | |
C7 | 0.4924 (3) | 0.0970 (4) | 0.8492 (3) | 0.0798 (18) | |
H7A | 0.5115 | 0.1353 | 0.8231 | 0.096* | |
H7B | 0.5370 | 0.0905 | 0.8729 | 0.096* | |
C8 | 0.4758 (3) | 0.0144 (4) | 0.8270 (2) | 0.0811 (18) | |
H8A | 0.5218 | −0.0232 | 0.8342 | 0.097* | |
H8B | 0.4730 | 0.0214 | 0.7911 | 0.097* | |
C9 | 0.3832 (3) | 0.2798 (3) | 0.60524 (17) | 0.0420 (10) | |
H9 | 0.3462 (19) | 0.3251 (18) | 0.6024 (14) | 0.034 (11)* | |
C10 | 0.4035 (2) | 0.2582 (3) | 0.65399 (18) | 0.0454 (11) | |
H10 | 0.376 (2) | 0.283 (2) | 0.6803 (11) | 0.049 (13)* | |
C11 | 0.4850 (3) | 0.2212 (4) | 0.66950 (19) | 0.0618 (14) | |
H11A | 0.5275 | 0.2435 | 0.6477 | 0.074* | |
H11B | 0.4973 | 0.2401 | 0.7031 | 0.074* | |
C12 | 0.4878 (3) | 0.1255 (4) | 0.66804 (18) | 0.0569 (13) | |
H12A | 0.5438 | 0.1076 | 0.6608 | 0.068* | |
H12B | 0.4734 | 0.1035 | 0.7007 | 0.068* | |
C13 | 0.4314 (2) | 0.0870 (3) | 0.63017 (16) | 0.0395 (10) | |
H13 | 0.409 (2) | 0.0370 (18) | 0.6407 (15) | 0.053 (13)* | |
C14 | 0.4256 (2) | 0.1116 (3) | 0.58242 (16) | 0.0385 (10) | |
H14 | 0.399 (2) | 0.076 (2) | 0.5604 (11) | 0.035 (11)* | |
C15 | 0.4765 (3) | 0.1803 (3) | 0.55893 (17) | 0.0521 (12) | |
H15A | 0.4877 | 0.1650 | 0.5246 | 0.063* | |
H15B | 0.5289 | 0.1840 | 0.5762 | 0.063* | |
C16 | 0.4352 (3) | 0.2658 (3) | 0.56028 (19) | 0.0592 (13) | |
H16A | 0.4770 | 0.3100 | 0.5589 | 0.071* | |
H16B | 0.4010 | 0.2716 | 0.5308 | 0.071* | |
C17 | 0.2195 (2) | −0.0158 (2) | 0.84536 (13) | 0.0268 (8) | |
C18 | 0.1040 (3) | −0.1135 (3) | 0.85686 (16) | 0.0452 (11) | |
H18A | 0.0546 | −0.0787 | 0.8550 | 0.054* | |
H18B | 0.0936 | −0.1604 | 0.8796 | 0.054* | |
C19 | 0.1239 (3) | −0.1476 (3) | 0.80667 (17) | 0.0488 (11) | |
H19A | 0.1702 | −0.1867 | 0.8089 | 0.059* | |
H19B | 0.0770 | −0.1788 | 0.7935 | 0.059* | |
C20 | 0.1447 (3) | −0.0753 (3) | 0.77315 (16) | 0.0486 (11) | |
H20A | 0.1654 | −0.0972 | 0.7417 | 0.058* | |
H20B | 0.0956 | −0.0419 | 0.7664 | 0.058* | |
C21 | 0.2480 (2) | 0.0378 (3) | 0.76332 (14) | 0.0395 (10) | |
H21A | 0.2705 | 0.0063 | 0.7353 | 0.047* | |
H21B | 0.2937 | 0.0637 | 0.7810 | 0.047* | |
C22 | 0.1927 (2) | 0.1073 (3) | 0.74396 (14) | 0.0373 (9) | |
H22A | 0.1545 | 0.1251 | 0.7697 | 0.045* | |
H22B | 0.1613 | 0.0866 | 0.7157 | 0.045* | |
C23 | 0.2462 (2) | 0.1819 (3) | 0.72838 (13) | 0.0355 (9) | |
H23A | 0.2623 | 0.2136 | 0.7579 | 0.043* | |
H23B | 0.2959 | 0.1600 | 0.7130 | 0.043* | |
C24 | 0.1405 (3) | 0.2910 (3) | 0.71502 (15) | 0.0438 (10) | |
H24A | 0.1573 | 0.3133 | 0.7472 | 0.053* | |
H24B | 0.0919 | 0.2560 | 0.7198 | 0.053* | |
C25 | 0.1214 (3) | 0.3630 (3) | 0.68061 (17) | 0.0451 (11) | |
H25A | 0.0730 | 0.3935 | 0.6923 | 0.054* | |
H25B | 0.1672 | 0.4028 | 0.6797 | 0.054* | |
C26 | 0.1061 (3) | 0.3280 (3) | 0.63002 (16) | 0.0447 (11) | |
H26A | 0.0572 | 0.2924 | 0.6305 | 0.054* | |
H26B | 0.0968 | 0.3746 | 0.6068 | 0.054* | |
C27 | 0.2226 (2) | 0.2346 (2) | 0.64542 (13) | 0.0264 (8) | |
C28 | 0.1766 (2) | −0.0514 (2) | 0.92925 (13) | 0.0331 (9) | |
H28 | 0.2234 | −0.0136 | 0.9360 | 0.040* | |
C29 | 0.1865 (2) | 0.2654 (3) | 0.55998 (14) | 0.0368 (9) | |
H29 | 0.2368 | 0.2317 | 0.5554 | 0.044* | |
C281 | 0.1927 (3) | −0.1345 (3) | 0.95619 (17) | 0.0528 (12) | |
H28A | 0.2419 | −0.1603 | 0.9433 | 0.079* | |
H28B | 0.1470 | −0.1725 | 0.9512 | 0.079* | |
H28C | 0.1993 | −0.1235 | 0.9912 | 0.079* | |
C282 | 0.1006 (3) | −0.0072 (3) | 0.94842 (16) | 0.0490 (11) | |
H28D | 0.0925 | 0.0452 | 0.9305 | 0.073* | |
H28E | 0.1072 | 0.0051 | 0.9833 | 0.073* | |
H28F | 0.0537 | −0.0437 | 0.9438 | 0.073* | |
C291 | 0.1980 (3) | 0.3475 (3) | 0.53222 (18) | 0.0625 (14) | |
H29A | 0.2437 | 0.3783 | 0.5462 | 0.094* | |
H29B | 0.1490 | 0.3814 | 0.5349 | 0.094* | |
H29C | 0.2088 | 0.3353 | 0.4978 | 0.094* | |
C292 | 0.1166 (3) | 0.2136 (3) | 0.53902 (17) | 0.0563 (13) | |
H29D | 0.1112 | 0.1614 | 0.5576 | 0.084* | |
H29E | 0.1276 | 0.2006 | 0.5047 | 0.084* | |
H29F | 0.0664 | 0.2458 | 0.5414 | 0.084* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Rh1 | 0.02475 (15) | 0.02505 (17) | 0.03142 (17) | −0.00038 (12) | −0.00464 (12) | 0.00325 (12) |
Rh2 | 0.02445 (15) | 0.02526 (17) | 0.02930 (16) | 0.00086 (12) | 0.00006 (11) | 0.00182 (12) |
Br1 | 0.0385 (2) | 0.0333 (2) | 0.0520 (3) | 0.00655 (18) | −0.00447 (18) | −0.00114 (19) |
Br2 | 0.0444 (3) | 0.0330 (2) | 0.0680 (3) | −0.00669 (19) | −0.0033 (2) | −0.0044 (2) |
N1 | 0.0352 (17) | 0.0279 (17) | 0.0307 (17) | −0.0085 (14) | −0.0037 (13) | 0.0025 (14) |
N4 | 0.0290 (16) | 0.0339 (18) | 0.0320 (18) | 0.0062 (14) | −0.0016 (13) | 0.0006 (14) |
N2 | 0.0377 (18) | 0.0363 (19) | 0.0280 (18) | −0.0069 (15) | −0.0054 (13) | 0.0036 (14) |
N3 | 0.0322 (17) | 0.0363 (19) | 0.0272 (18) | 0.0076 (14) | 0.0031 (13) | 0.0045 (14) |
C1 | 0.036 (2) | 0.041 (3) | 0.062 (3) | 0.011 (2) | 0.001 (2) | −0.009 (2) |
C2 | 0.040 (2) | 0.031 (2) | 0.065 (3) | 0.007 (2) | −0.017 (2) | 0.008 (2) |
C3 | 0.095 (4) | 0.066 (4) | 0.077 (4) | 0.015 (3) | −0.051 (3) | 0.008 (3) |
C4 | 0.104 (5) | 0.061 (4) | 0.073 (4) | −0.003 (3) | −0.051 (3) | 0.003 (3) |
C5 | 0.047 (3) | 0.038 (3) | 0.061 (3) | −0.004 (2) | −0.025 (2) | −0.005 (2) |
C6 | 0.035 (2) | 0.037 (3) | 0.081 (4) | −0.009 (2) | −0.007 (2) | 0.008 (2) |
C7 | 0.047 (3) | 0.075 (4) | 0.118 (5) | −0.017 (3) | 0.024 (3) | 0.000 (4) |
C8 | 0.048 (3) | 0.090 (5) | 0.105 (5) | 0.000 (3) | 0.026 (3) | −0.009 (4) |
C9 | 0.037 (2) | 0.028 (2) | 0.061 (3) | −0.0046 (19) | 0.007 (2) | 0.001 (2) |
C10 | 0.031 (2) | 0.051 (3) | 0.054 (3) | −0.008 (2) | −0.001 (2) | −0.017 (2) |
C11 | 0.035 (2) | 0.085 (4) | 0.066 (3) | −0.003 (3) | −0.013 (2) | −0.016 (3) |
C12 | 0.034 (2) | 0.084 (4) | 0.052 (3) | 0.012 (2) | −0.005 (2) | 0.014 (3) |
C13 | 0.027 (2) | 0.042 (3) | 0.049 (3) | 0.0093 (18) | 0.0050 (18) | 0.011 (2) |
C14 | 0.034 (2) | 0.038 (2) | 0.043 (3) | 0.0072 (19) | 0.0063 (18) | −0.004 (2) |
C15 | 0.048 (3) | 0.063 (3) | 0.046 (3) | 0.002 (2) | 0.016 (2) | 0.009 (2) |
C16 | 0.057 (3) | 0.052 (3) | 0.069 (3) | −0.011 (3) | 0.022 (2) | 0.017 (3) |
C17 | 0.0278 (19) | 0.0232 (19) | 0.029 (2) | 0.0052 (16) | −0.0032 (15) | 0.0003 (15) |
C18 | 0.044 (2) | 0.042 (3) | 0.049 (3) | −0.017 (2) | −0.002 (2) | −0.002 (2) |
C19 | 0.059 (3) | 0.038 (3) | 0.050 (3) | −0.011 (2) | −0.008 (2) | −0.008 (2) |
C20 | 0.060 (3) | 0.048 (3) | 0.038 (2) | −0.010 (2) | −0.016 (2) | −0.003 (2) |
C21 | 0.039 (2) | 0.051 (3) | 0.029 (2) | 0.002 (2) | 0.0016 (17) | 0.0095 (19) |
C22 | 0.034 (2) | 0.047 (3) | 0.031 (2) | −0.0024 (18) | −0.0012 (16) | 0.0110 (19) |
C23 | 0.034 (2) | 0.045 (2) | 0.027 (2) | 0.0012 (18) | −0.0025 (16) | 0.0057 (18) |
C24 | 0.046 (2) | 0.046 (3) | 0.040 (2) | 0.010 (2) | 0.0085 (19) | −0.003 (2) |
C25 | 0.045 (2) | 0.035 (2) | 0.054 (3) | 0.013 (2) | 0.009 (2) | −0.003 (2) |
C26 | 0.039 (2) | 0.043 (3) | 0.052 (3) | 0.017 (2) | −0.0019 (19) | 0.002 (2) |
C27 | 0.0277 (18) | 0.0199 (18) | 0.032 (2) | −0.0014 (15) | 0.0031 (15) | 0.0058 (15) |
C28 | 0.040 (2) | 0.031 (2) | 0.028 (2) | −0.0028 (17) | 0.0012 (16) | 0.0057 (17) |
C29 | 0.040 (2) | 0.042 (2) | 0.029 (2) | 0.0047 (19) | −0.0057 (17) | 0.0047 (18) |
C281 | 0.070 (3) | 0.044 (3) | 0.045 (3) | 0.008 (2) | 0.005 (2) | 0.015 (2) |
C282 | 0.051 (3) | 0.048 (3) | 0.048 (3) | 0.008 (2) | 0.008 (2) | 0.003 (2) |
C291 | 0.095 (4) | 0.051 (3) | 0.041 (3) | 0.004 (3) | −0.004 (2) | 0.014 (2) |
C292 | 0.054 (3) | 0.064 (3) | 0.050 (3) | −0.006 (2) | −0.017 (2) | −0.002 (2) |
Rh1—C17 | 2.033 (4) | C12—H12A | 0.9800 |
Rh1—C1 | 2.104 (4) | C12—H12B | 0.9800 |
Rh1—C2 | 2.108 (4) | C13—C14 | 1.355 (6) |
Rh1—C5 | 2.198 (4) | C13—H13 | 0.918 (19) |
Rh1—C6 | 2.207 (4) | C14—C15 | 1.510 (6) |
Rh1—Br1 | 2.5239 (5) | C14—H14 | 0.935 (18) |
Rh2—C27 | 2.043 (3) | C15—C16 | 1.512 (7) |
Rh2—C9 | 2.103 (4) | C15—H15A | 0.9800 |
Rh2—C10 | 2.121 (4) | C15—H15B | 0.9800 |
Rh2—C13 | 2.191 (4) | C16—H16A | 0.9800 |
Rh2—C14 | 2.210 (4) | C16—H16B | 0.9800 |
Rh2—Br2 | 2.5205 (5) | C18—C19 | 1.499 (6) |
N1—C17 | 1.346 (5) | C18—H18A | 0.9800 |
N1—C18 | 1.461 (5) | C18—H18B | 0.9800 |
N1—C28 | 1.476 (5) | C19—C20 | 1.499 (6) |
N4—C27 | 1.338 (5) | C19—H19A | 0.9800 |
N4—C26 | 1.460 (5) | C19—H19B | 0.9800 |
N4—C29 | 1.483 (5) | C20—H20A | 0.9800 |
N2—C17 | 1.350 (5) | C20—H20B | 0.9800 |
N2—C21 | 1.461 (5) | C21—C22 | 1.518 (5) |
N2—C20 | 1.466 (5) | C21—H21A | 0.9800 |
N3—C27 | 1.346 (5) | C21—H21B | 0.9800 |
N3—C23 | 1.460 (5) | C22—C23 | 1.529 (6) |
N3—C24 | 1.465 (5) | C22—H22A | 0.9800 |
C1—C2 | 1.393 (7) | C22—H22B | 0.9800 |
C1—C8 | 1.505 (7) | C23—H23A | 0.9800 |
C1—H1 | 0.927 (19) | C23—H23B | 0.9800 |
C2—C3 | 1.515 (6) | C24—C25 | 1.504 (6) |
C2—H2 | 0.910 (19) | C24—H24A | 0.9800 |
C3—C4 | 1.459 (8) | C24—H24B | 0.9800 |
C3—H3A | 0.9800 | C25—C26 | 1.500 (6) |
C3—H3B | 0.9800 | C25—H25A | 0.9800 |
C4—C5 | 1.498 (7) | C25—H25B | 0.9800 |
C4—H4A | 0.9800 | C26—H26A | 0.9800 |
C4—H4B | 0.9800 | C26—H26B | 0.9800 |
C5—C6 | 1.351 (7) | C28—C282 | 1.520 (6) |
C5—H5 | 0.928 (19) | C28—C281 | 1.525 (6) |
C6—C7 | 1.513 (7) | C28—H28 | 0.9900 |
C6—H6 | 0.930 (18) | C29—C291 | 1.511 (6) |
C7—C8 | 1.463 (8) | C29—C292 | 1.519 (6) |
C7—H7A | 0.9800 | C29—H29 | 0.9900 |
C7—H7B | 0.9800 | C281—H28A | 0.9700 |
C8—H8A | 0.9800 | C281—H28B | 0.9700 |
C8—H8B | 0.9800 | C281—H28C | 0.9700 |
C9—C10 | 1.405 (6) | C282—H28D | 0.9700 |
C9—C16 | 1.504 (6) | C282—H28E | 0.9700 |
C9—H9 | 0.941 (18) | C282—H28F | 0.9700 |
C10—C11 | 1.519 (6) | C291—H29A | 0.9700 |
C10—H10 | 0.932 (19) | C291—H29B | 0.9700 |
C11—C12 | 1.513 (8) | C291—H29C | 0.9700 |
C11—H11A | 0.9800 | C292—H29D | 0.9700 |
C11—H11B | 0.9800 | C292—H29E | 0.9700 |
C12—C13 | 1.510 (7) | C292—H29F | 0.9700 |
C17—Rh1—C1 | 90.89 (16) | C14—C13—H13 | 121 (3) |
C17—Rh1—C2 | 91.66 (15) | C12—C13—H13 | 112 (3) |
C1—Rh1—C2 | 38.61 (18) | Rh2—C13—H13 | 101 (3) |
C17—Rh1—C5 | 161.56 (17) | C13—C14—C15 | 124.7 (4) |
C1—Rh1—C5 | 94.95 (19) | C13—C14—Rh2 | 71.3 (2) |
C2—Rh1—C5 | 82.20 (17) | C15—C14—Rh2 | 110.7 (3) |
C17—Rh1—C6 | 162.59 (17) | C13—C14—H14 | 118 (2) |
C1—Rh1—C6 | 80.86 (18) | C15—C14—H14 | 115 (2) |
C2—Rh1—C6 | 91.34 (18) | Rh2—C14—H14 | 102 (2) |
C5—Rh1—C6 | 35.71 (18) | C14—C15—C16 | 112.5 (3) |
C17—Rh1—Br1 | 89.38 (10) | C14—C15—H15A | 109.1 |
C1—Rh1—Br1 | 159.60 (13) | C16—C15—H15A | 109.1 |
C2—Rh1—Br1 | 161.76 (14) | C14—C15—H15B | 109.1 |
C5—Rh1—Br1 | 91.15 (12) | C16—C15—H15B | 109.1 |
C6—Rh1—Br1 | 93.08 (13) | H15A—C15—H15B | 107.8 |
C27—Rh2—C9 | 90.25 (15) | C9—C16—C15 | 114.0 (4) |
C27—Rh2—C10 | 92.15 (16) | C9—C16—H16A | 108.8 |
C9—Rh2—C10 | 38.84 (18) | C15—C16—H16A | 108.8 |
C27—Rh2—C13 | 158.99 (15) | C9—C16—H16B | 108.8 |
C9—Rh2—C13 | 97.05 (16) | C15—C16—H16B | 108.8 |
C10—Rh2—C13 | 81.59 (17) | H16A—C16—H16B | 107.7 |
C27—Rh2—C14 | 164.93 (15) | N1—C17—N2 | 117.8 (3) |
C9—Rh2—C14 | 81.46 (16) | N1—C17—Rh1 | 122.6 (3) |
C10—Rh2—C14 | 89.25 (17) | N2—C17—Rh1 | 119.6 (3) |
C13—Rh2—C14 | 35.85 (15) | N1—C18—C19 | 110.0 (3) |
C27—Rh2—Br2 | 89.27 (10) | N1—C18—H18A | 109.7 |
C9—Rh2—Br2 | 158.18 (13) | C19—C18—H18A | 109.7 |
C10—Rh2—Br2 | 162.95 (14) | N1—C18—H18B | 109.7 |
C13—Rh2—Br2 | 91.07 (12) | C19—C18—H18B | 109.7 |
C14—Rh2—Br2 | 93.78 (11) | H18A—C18—H18B | 108.2 |
C17—N1—C18 | 122.7 (3) | C20—C19—C18 | 109.0 (4) |
C17—N1—C28 | 120.1 (3) | C20—C19—H19A | 109.9 |
C18—N1—C28 | 116.4 (3) | C18—C19—H19A | 109.9 |
C27—N4—C26 | 122.3 (3) | C20—C19—H19B | 109.9 |
C27—N4—C29 | 119.7 (3) | C18—C19—H19B | 109.9 |
C26—N4—C29 | 117.4 (3) | H19A—C19—H19B | 108.3 |
C17—N2—C21 | 119.2 (3) | N2—C20—C19 | 109.9 (3) |
C17—N2—C20 | 124.6 (3) | N2—C20—H20A | 109.7 |
C21—N2—C20 | 115.6 (3) | C19—C20—H20A | 109.7 |
C27—N3—C23 | 119.8 (3) | N2—C20—H20B | 109.7 |
C27—N3—C24 | 124.1 (3) | C19—C20—H20B | 109.7 |
C23—N3—C24 | 115.3 (3) | H20A—C20—H20B | 108.2 |
C2—C1—C8 | 125.8 (5) | N2—C21—C22 | 113.4 (3) |
C2—C1—Rh1 | 70.9 (2) | N2—C21—H21A | 108.9 |
C8—C1—Rh1 | 112.6 (3) | C22—C21—H21A | 108.9 |
C2—C1—H1 | 114 (3) | N2—C21—H21B | 108.9 |
C8—C1—H1 | 114 (3) | C22—C21—H21B | 108.9 |
Rh1—C1—H1 | 110 (3) | H21A—C21—H21B | 107.7 |
C1—C2—C3 | 123.7 (5) | C21—C22—C23 | 108.1 (3) |
C1—C2—Rh1 | 70.5 (2) | C21—C22—H22A | 110.1 |
C3—C2—Rh1 | 111.2 (3) | C23—C22—H22A | 110.1 |
C1—C2—H2 | 122 (3) | C21—C22—H22B | 110.1 |
C3—C2—H2 | 112 (3) | C23—C22—H22B | 110.1 |
Rh1—C2—H2 | 105 (3) | H22A—C22—H22B | 108.4 |
C4—C3—C2 | 117.2 (4) | N3—C23—C22 | 113.7 (3) |
C4—C3—H3A | 108.0 | N3—C23—H23A | 108.8 |
C2—C3—H3A | 108.0 | C22—C23—H23A | 108.8 |
C4—C3—H3B | 108.0 | N3—C23—H23B | 108.8 |
C2—C3—H3B | 108.0 | C22—C23—H23B | 108.8 |
H3A—C3—H3B | 107.2 | H23A—C23—H23B | 107.7 |
C3—C4—C5 | 115.6 (4) | N3—C24—C25 | 109.3 (3) |
C3—C4—H4A | 108.4 | N3—C24—H24A | 109.8 |
C5—C4—H4A | 108.4 | C25—C24—H24A | 109.8 |
C3—C4—H4B | 108.4 | N3—C24—H24B | 109.8 |
C5—C4—H4B | 108.4 | C25—C24—H24B | 109.8 |
H4A—C4—H4B | 107.4 | H24A—C24—H24B | 108.3 |
C6—C5—C4 | 126.5 (5) | C26—C25—C24 | 108.9 (3) |
C6—C5—Rh1 | 72.5 (3) | C26—C25—H25A | 109.9 |
C4—C5—Rh1 | 107.9 (3) | C24—C25—H25A | 109.9 |
C6—C5—H5 | 119 (3) | C26—C25—H25B | 109.9 |
C4—C5—H5 | 113 (3) | C24—C25—H25B | 109.9 |
Rh1—C5—H5 | 99 (3) | H25A—C25—H25B | 108.3 |
C5—C6—C7 | 125.3 (5) | N4—C26—C25 | 110.1 (3) |
C5—C6—Rh1 | 71.8 (3) | N4—C26—H26A | 109.6 |
C7—C6—Rh1 | 110.7 (3) | C25—C26—H26A | 109.6 |
C5—C6—H6 | 114 (2) | N4—C26—H26B | 109.6 |
C7—C6—H6 | 119 (2) | C25—C26—H26B | 109.6 |
Rh1—C6—H6 | 101 (2) | H26A—C26—H26B | 108.2 |
C8—C7—C6 | 115.8 (4) | N4—C27—N3 | 118.8 (3) |
C8—C7—H7A | 108.3 | N4—C27—Rh2 | 123.1 (3) |
C6—C7—H7A | 108.3 | N3—C27—Rh2 | 118.0 (2) |
C8—C7—H7B | 108.3 | N1—C28—C282 | 110.4 (3) |
C6—C7—H7B | 108.3 | N1—C28—C281 | 112.6 (3) |
H7A—C7—H7B | 107.4 | C282—C28—C281 | 111.9 (3) |
C7—C8—C1 | 115.7 (5) | N1—C28—H28 | 107.2 |
C7—C8—H8A | 108.4 | C282—C28—H28 | 107.2 |
C1—C8—H8A | 108.4 | C281—C28—H28 | 107.2 |
C7—C8—H8B | 108.4 | N4—C29—C291 | 113.0 (4) |
C1—C8—H8B | 108.4 | N4—C29—C292 | 110.6 (3) |
H8A—C8—H8B | 107.4 | C291—C29—C292 | 111.8 (4) |
C10—C9—C16 | 126.3 (4) | N4—C29—H29 | 107.0 |
C10—C9—Rh2 | 71.3 (2) | C291—C29—H29 | 107.0 |
C16—C9—Rh2 | 109.8 (3) | C292—C29—H29 | 107.0 |
C10—C9—H9 | 114 (2) | C28—C281—H28A | 109.5 |
C16—C9—H9 | 114 (2) | C28—C281—H28B | 109.5 |
Rh2—C9—H9 | 111 (2) | H28A—C281—H28B | 109.5 |
C9—C10—C11 | 124.2 (4) | C28—C281—H28C | 109.5 |
C9—C10—Rh2 | 69.9 (2) | H28A—C281—H28C | 109.5 |
C11—C10—Rh2 | 113.2 (3) | H28B—C281—H28C | 109.5 |
C9—C10—H10 | 120 (3) | C28—C282—H28D | 109.5 |
C11—C10—H10 | 112 (3) | C28—C282—H28E | 109.5 |
Rh2—C10—H10 | 106 (3) | H28D—C282—H28E | 109.5 |
C12—C11—C10 | 113.9 (4) | C28—C282—H28F | 109.5 |
C12—C11—H11A | 108.8 | H28D—C282—H28F | 109.5 |
C10—C11—H11A | 108.8 | H28E—C282—H28F | 109.5 |
C12—C11—H11B | 108.8 | C29—C291—H29A | 109.5 |
C10—C11—H11B | 108.8 | C29—C291—H29B | 109.5 |
H11A—C11—H11B | 107.7 | H29A—C291—H29B | 109.5 |
C13—C12—C11 | 113.6 (4) | C29—C291—H29C | 109.5 |
C13—C12—H12A | 108.8 | H29A—C291—H29C | 109.5 |
C11—C12—H12A | 108.8 | H29B—C291—H29C | 109.5 |
C13—C12—H12B | 108.8 | C29—C292—H29D | 109.5 |
C11—C12—H12B | 108.8 | C29—C292—H29E | 109.5 |
H12A—C12—H12B | 107.7 | H29D—C292—H29E | 109.5 |
C14—C13—C12 | 125.3 (4) | C29—C292—H29F | 109.5 |
C14—C13—Rh2 | 72.8 (2) | H29D—C292—H29F | 109.5 |
C12—C13—Rh2 | 108.6 (3) | H29E—C292—H29F | 109.5 |
Experimental details
Crystal data | |
Chemical formula | [Rh2Br2(C8H12)2(C17H32N4)] |
Mr | 874.46 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 233 |
a, b, c (Å) | 16.4075 (2), 15.7975 (3), 27.1065 (4) |
V (Å3) | 7025.94 (19) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 3.24 |
Crystal size (mm) | 0.2 × 0.1 × 0.08 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | Multi-scan (SORTAV; Blessing, 1995) |
Tmin, Tmax | 0.432, 0.755 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 57878, 6186, 5045 |
Rint | 0.083 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.078, 1.06 |
No. of reflections | 6186 |
No. of parameters | 402 |
No. of restraints | 8 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
w = 1/[σ2(Fo2) + (0.0254P)2 + 11.9446P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 0.95, −0.51 |
Computer programs: COLLECT (Nonius, 1998), DENZO-SMN (Otwinowski & Minor, 1997), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SHELXS86 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010).
Acknowledgements
Financial support provided by the DFG (BU 2174/8–1) is greatfully acknowledged.
References
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The hydroformylation reaction is one of the most important catalytic reactions at an industrial level that can be employed for the conversion of alkenes, carbon monoxide and hydrogen into aldehydes and alcohols. Most of the hydroformylation catalysts so far were based on rhodium and phosphine ligands (e.g., the Wilkinson-catalyst [RhCl(PPh3)3] (Evans et al., 1968). However, phosphine ligands have some common disadvantages as they are easily oxidized by molecular oxygen in solution. Furthermore, phosphines and CO show similar binding constants to rhodium. Due to the fact that CO-pressures applied during hydroformylation are quite high, an excess of phosphine is required to generate a sterically demanding environment around the active rhodium-center, a prerequisite for high n/iso-ratios. N-heterocyclic carbenes (NHCs), owing to their strong σ donation and the excellent stability, have been widely applied as an ideal replacement for phosphines in the area of organometallic catalysis (Díez-González et al., 2009). Within that context, homobimetallic rhodium(I) NHC complexes have been reported to represent versatile catalysts for the hydrosilylation of e.g. aldehydes, ketones, alkenes, nitriles, isocyanates and tertiary amides. (Huckaba et al., 2013). The title compound was prepared by the reaction of 3,3'- (propane-1,3-diyl)bis(1-isopropyl-3,4,5,6-tetrahydropyrimidin-1-ium) bromide and [{Rh(cod)Cl}2] in anhydrous THF. It crystallizes in the space group Pbca (No.61). The structure exhibits a typical pesudo-square planar ligand environment for the Rh(I) centers which are coordinated by a bidentate cycloocta-1,5-diene (cod) ligand, one carbon atom of the bridging bis-N-heterocyclic carbene ligand and one bromide atom. The molecular structure is closely similar to that of the recently reported compounds bromo(η4-1,5-cyclooctadiene){1,3-bis(2-propyl)-3,4,5,6- tetrahydropyrimidin- 2-ylidene}rhodium and bromo(η4-1,5-cyclooctadiene){1,3-dimesityl-3,4,5,6- tetrahydropyrimidin- 2-ylidene}rhodium (Mayr et al., 2004).