Inorganic Chemistry
RhCl(COD)(NHC)] and proteins at the molecular level and
the related ligand exchange reactions occurring at the Rh
center.
Article
[
H
2
O 5:95 and 0.1% TFA to acetonitrile/H
2
O 95:5 and 0.1% TFA,
column: Macherey Nagel EC 125/4 Nucleodur C4 Gravity 5 μm):
8
.6 min.
Protein Crystallography. HEWL crystals of 0.1−0.2 mm were
grown from a reservoir solution consisting of sodium chloride (0.8 M)
and sodium acetate (0.1 M, pH 4.7) which, in the crystallization drop,
EXPERIMENTAL SECTION
Synthesis of Amino Acid Derivatives. Compounds 4−6 and
peptide 7 were synthesized according to literature procedures. The
■
7
5
was mixed with an equal volume of HEWL (100 mg/mL). Crystals
formed within 24 h and were then transferred into a drop of reservoir
solution of sodium nitrate (0.8 M) and sodium acetate (0.1 M, pH
4.7) supplemented with 8b (0.69 mg, 2 mg/mL). The crystals were
observed to turn orange after 3 d, and X-ray analysis was performed
after soaking for periods of 1 week and 1 month. For this purpose, the
soaked crystals were transferred into a cryoprotectant of 20% glycerol,
sodium nitrate (0.8 M), and sodium acetate (0.1 M, pH 4.7) and flash
frozen in liquid nitrogen.
Protein Crystal Data Collection and Analysis. X-ray diffraction
data were collected on the crystallography beamline MX1 at the
Australian Synchrotron. Data were processed with XDS, revealing
that the protein crystallized in the space group P4 2 2. The structures
33
Synthesis of [Rh(NHC)(COD)Cl] Complexes (8a−8c). General
Procedure. In a heated Schlenk flask under N atmosphere, 1 equiv of
2
the respective imidazolium salt was dissolved in 15 mL of dry
dichloromethane (DCM) (in case of ligands 2 and 5) or dry
acetonitrile (ACN) (in case of peptide 7). The solution was degassed
by three consecutive cycles of freeze−pump−thaw. After addition of
7
6
77
0
1
.5 equiv of Ag O, the solution was left to stir at room temperature for
2
h in the dark, during which a disappearance of the black Ag O could
2
3
1
be seen, followed by an addition of 0.5 equiv of [Rh(COD)Cl]2
leading to a color change to bright yellow. The solution was then left
to stir overnight at room temperature. Afterward the reaction mixture
was filtered through Celite (DCM/MeOH 9:1), and the filtrate was
concentrated under reduced pressure. Purification of the product was
carried out by flash column chromatography (n-hexane/ethyl acetate
were determined by molecular replacement using a monomer of
lysozyme (PDB ID: 4NHI) as a search model in PHASER. The
models were refined with iterative rounds of refinement and model
building in REFMAC and COOT. Sodium ion placement was
57
78
7
9
80
8
1
aided by the use of the WASP server at USF. The 2F −F , F −F ,
o
c
o
c
8
2
and anomalous difference maps were generated using FFT. To
further support the positioning of the organometallic moieties, maps
were generated of unbiased density, of simulated annealing composite
0
:1 to 1:0), leading to the products as bright yellow solids. The
peptide conjugate 8c was further purified by semipreparative HPLC
on a VarioPrep 125/10 Nucleodur C4 Gravity 5 μm column with a
83
84
omit, and with phenix.polder. The compound fragment formed
was reformatted (from the small molecule crystal structure of an
gradient of ACN/H O and 0.1% of trifluoroacetic acid (TFA) (5:95
2
8
5
86
to 95:5 v/v).
analogous [Ir(Cl)(COD)(NHC)] complex) using Gaussian, and
the final PDB and CIF files were generated by phenix.elbow.
87
Chloro-(1,5-cyclooctadiene)(1,3-dimethyl-1H-imidazol-3-ide)-
rhodium(I) (8a). Yield: 125 mg (0.33 mmol, 55%). Analytical data:
1
H NMR (200 MHz, chloroform-d) δ 6.79 (s, 2H, N−CHCH−N),
ASSOCIATED CONTENT
sı Supporting Information
■
5
.01 (s, 2H, 2x COD CH), 4.06 (s, 6H, 2x N−CH ), 3.28 (s, 2H, 2x
3
*
COD CH), 2.39 (t, J = 7.1 Hz, 4H, 2x COD CH ), 1.93 (m, 4H, 2x
2
COD CH2). 13C NMR (101 MHz, chloroform-d) δ 182.7 (d, J = 50.6
Hz, N−C−N), 122.0 (N−CHCH−N), 98.6 (d, J = 6.8 Hz, COD
CH), 67.8 (d, J = 14.5 Hz, COD CH), 37.8 (N−CH ), 33.1 (COD
3
General experimental information, detailed synthesis
procedures for all compounds, supplementary figures
and spectra (NMR, MS, including high-resolution MS of
+
CH ), 29.0 (COD CH ), ESI-MS: m/z 307.5 [M − Cl] .
2
2
Chloro-1,5-cyclooctadiene-[4-(2-((tert-butoxycarbonyl)amino)-
-methoxy-3-oxopropyl)-1,3-dimethyl-1H-imidazol-3-ide]-
3
8
c), chromatograms of all metal-containing compounds,
rhodium(I) (8b). Yield: 60 mg (0.11 mmol, 39%). Analytical data: R
f
1
(
ehtylacetate/n-hexane, 1:1): 0.13. H NMR (400 MHz, chloroform-
and additional crystallographic data and figures (PDF)
d, mixture of two isomers) δ 6.60 (d, J = 15.7 Hz, 2H, 2x N−CH =
C), 5.01 (m, 6H, 6x COD CH, NH), 4.55 (dd, J = 12.0, 7.6 Hz, 2H,
Corresponding Author
■
2
x α-CH), 4.01 (m, 12H, 4x N−CH ), 3.74 (d, J = 20.2 Hz, 6H, 2x
3
O−CH ), 3.27 (m, 4H, 2x COD CH), 2.93 (m, 4H, 2x β-CH ), 2.39
3
2
Nils Metzler-Nolte − Inorganic Chemistry I − Bioinorganic
(
qd, J = 12.4, 10.0, 5.5 Hz, 8H, 4x COD CH ), 1.94 (m, 8H, 4x COD
2
13
CH ), 1.42 (d, J = 19.7 Hz, 18H, 6x Boc CH ). C NMR (101 MHz,
2
3
chloroform-d) δ 171.7 (COOMe), 155.1 (CO-NH), 129.1 (N−C
CH), 120.2 (N−CHC), 98.6 (d, J = 10.1 Hz, COD CH), 80.5
(
Boc quat. C), 68.0 (m, COD CH), 52.6 (m, COD CH, α-CH, O−
CH ), 37.8 (d, J = 8.0 Hz, N−CH ), 35.1 (N−CH ), 33.1 (m, COD
CH ), 31.7 (COD CH ), 29.0 (m, COD CH ), 28.4 (d, J = 6.5 Hz,
3
3
3
2
2
2
Authors
Boc CH ), 28.0 (d, J = 32.3 Hz, COD CH ). ESI-MS: m/z 508.5 [M
Isabelle M. Daubit − Inorganic Chemistry I − Bioinorganic
Universität Bochum, 44801 Bochum, Germany
Matthew P. Sullivan − School of Chemical Sciences and School
Milena John − Inorganic Chemistry I − Bioinorganic
Universität Bochum, 44801 Bochum, Germany
3
2
+
+
−
Cl] , 565.9 [M + Na] .
Chloro-1,5-cyclooctadiene-[5-(13-((tert-butoxycarbonyl)amino)-
0-isobutyl-7-isopropyl-4-methyl-3,6,9,12-tetraoxo-2-oxa-5,8,11-
triazatetradecan-14-yl)-1,3-dimethyl-1H-imidazol-3-ide]-rhodium-
I) (8c). Yield: 13 mg (0.016 mmol, 32%). Analytical data: R (ethyl
1
(
f
1
acetate): 0.50. H NMR (300 MHz, chloroform-d, mixture of two
isomers) δ 6.65 (s, 2H, 2x N−CHC), 5.40 (m, 2H, 2x COD CH),
4
.98 (s, 4H, 4x COD CH), 4.19 (m, 19H, 6x α-CH, 4x N−CH ), 3.74
3
(
d, J = 4.7 Hz, 6H, 2x O−CH ), 3.48 (d, J = 3.1 Hz, 2H, 2x COD
3
CH), 3.28 (s, 2H, 2x COD CH), 2.84 (m, 4H, 2x β-CH ), 2.39 (d, J =
2
1
1.1 Hz, 8H, 4x COD CH ), 2.01 (dd, J = 44.5, 8.7 Hz, 8H, 2x Val
2
CH, 3x COD CH ), 1.58 (q, J = 9.3, 8.9 Hz, 6H, 2x Leu CH, 2x Leu
2
CH ), 1.41 (t, J = 6.7 Hz, 24H, 6x Boc CH , 2x Ala CH ), 0.93 (dq, J
2
3
3
Christian G. Hartinger − School of Chemical Sciences,
=
12.9, 5.6, 4.8 Hz, 24H, 4x Val CH , 4x Leu CH ). ESI-MS: m/z
3 3
+
+
7
91.7 [M − Cl] . HR ESI-MS: m/z 791.3594 [M − Cl] , 849.3177
+
[
M + Na] . Analytical HPLC retention time: (gradient: acetonitrile/
F
Inorg. Chem. XXXX, XXX, XXX−XXX