The first crystallographically characterised ruthenium(vi) alkylimido porphyrin competent for aerobic epoxidation and hydrogen atom abstraction

Article abstract of DOI:10.1039/c9cc09972g

The syntheses of [Ru^VI(Por)(NAd)(O)] and [Ru^VI(2,6-F₂-TPP)(NAd)₂] have been described. [Ru^VI(2,6-F₂-TPP)(NAd)(O)] capable of catalysing aerobic epoxidation of alkenes has been characterised by X-ray crystallography with RuNAd and RuO bond distances being 1.778(5) ? and 1.760(4) ? (∠O-Ru-NAd: 174.37(19)°), respectively. Its first reduction potential is 740 mV cathodically shifted from that of [Ru^VI(2,6-F₂-TPP)(O)₂].

Full text of DOI:10.1039/c9cc09972g

View Article Online
View Journal
ChemComm
Chemical Communications
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: K. P. Shing, Q.
Wan, X. Chang and C. Che, Chem. Commun., 2020, DOI: 10.1039/C9CC09972G.
Volume 54
This is an Accepted Manuscript, which has been through the
Number
January 2018
Pages 1-112
1
4
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Chemical Communications
rsc.li/chemcomm
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1359-7345
COMMUNICATION
S. J. Connon, M. O. Senge et al.
Conformational control of nonplanar free base porphyrins:
towards bifunctional catalysts of tunable basicity
rsc.li/chemcomm

Please do not adjust margins
Page 1 of 4
ChemComm
View Article Online
DOI: 10.1039/C9CC09972G
COMMUNICATION
The first crystallographically characterised ruthenium(VI)
alkylimido porphyrin competent for aerobic epoxidation and
hydrogen atom abstraction
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Ka-Pan Shing,a Qingyun Wan,a Xiao-Yong Changa and Chi-Ming Che*ab
The syntheses of [RuVI(Por)(NAd)(O)] and [RuVI(2,6-F2-TPP)(NAd)2]
were described. [RuVI(2,6-F2-TPP)(NAd)(O)] capable of catalysing
aerobic epoxidation of alkenes has been characterised by X-ray
crystallography with Ru=NAd and Ru=O bond distances being
1.778(5) Å and 1.760(4) Å (∠O-Ru-NAd: 174.37(19)o), respectively.
Its first reduction potential is 740 mV cathodically shifted from
that of [RuVI(2,6-F2-TPP)(O)2].
Cl
ACN
RuII
NAd
RuVI
NAd
RuVI
Zn dust
excess AdN3
benzene, RT
H2O
RuIII
benzene, RT
ACN/PhF,
reflux
NAd
s
O
4
THF
ACN
2
e
y
n
a
a
d
x
stable for at least
several days at RT
1
3
r
e
i
e
h
-
v
n
o
NH2Ad
g
n
d
2 4 5:
,
,
characterised by
n
RuII
t
a
s
X-ray crystallography
no CN bond cleavage
6
NH2Ad
5
observed
(1:
reported previously )
Isolation and reactivity studies of metal-imido species are
instrumental to understanding burgeoning nitrene-transfer
reactions and designing efficient catalysts through structure-
reactivity studies. In recent years, intra-1 and intermolecular2
C‒H amination reactions mediated by late-transition-metal-
imido or -alkyliminyl species have garnered much attention,1,2
but such species are usually short lived in solution. For the
literature reported isolable metal-imido/nitrene species, many
examples are of low coordination number (2–4);3 examples of
isolable yet reactive 5- and 6-coordinate metal-imido
complexes are relatively sparse.1f,4 Metal-alkylimido complexes,
which could readily undergo 1,2-hydride migration and/or C‒N
bond cleavage,1a,2d are intrinsically more unstable than non-
aliphatic imide analogues. As to Group-8 alkylimido porphyrins,
only [OsVI(4-Cl-TPP)(NBut)2] and [OsVI(TTP)(NBut)(O)] have been
characterised by X-ray crystallography;5 no X-ray crystal
structure has been reported for their Ru counterparts (in
contrast to aryl- and sulfonylimides [RuVI(Por)(NAr)2]4e,f and
[RuVI(Por)(NSO2Ar)2]4b,d which could be isolated and purified by
chromatography in air). Herein we report a crystallographically
characterised Ru(VI) alkylimido porphyrin which can mediate
hydrogen atom abstraction and aerobic alkene oxidation reactions.
Reduction of [RuIII(2,6-F2-TPP)(Cl)(THF)] 6 (1) to air-sensitive
[RuII(2,6-F2-TPP)(ACN)2] (2), followed by reaction with excess
= Por = tetrakis(2,6-difluorophenyl)porphyrin dianion = 2,6-F2-TPP
Por
NH2Ad
RuII
NAd
O2 (1 atm)
4
6
7
2,6-F2-TPP
2,6-Cl2-TPP
TMP
(see Electronic Supplementary
Information)
RuVI
O
60 oC, CH2Cl2
NH2Ad
Scheme 1 Preparation of ruthenium complexes 2‒7.
adamantyl azide (AdN3), gave Ru(VI)-bis(alkylimido) complex
[RuVI(2,6-F2-TPP)(NAd)2] (3, Scheme 1). Complex 3 readily
underwent hydrolysis to form Ru(VI)-oxo(alkylimido) complex
[RuVI(2,6-F2-TPP)(NAd)(O)] (4, which is air-stable in CH2Cl2/C6H6
over days). Previously [RuVI(Por)(NBut)(O)] (Por = 4-Cl-TPP, TPP,
3,4,5-(MeO)3-TPP) were synthesised from [RuVI(Por)(O)2] and
tBuNH2 via isolation of [RuII(Por)(NH2But)] with subsequent
oxidation by bromine7 which requires careful addition of
bromine to minimise formation of side product(s). Using 1 as
starting material, its reduction to 2 (after overnight reflux) is
nearly quantitative, and the reaction of 2 with excess AdN3 in
anhydrous benzene afforded 3 with no side product(s)
detected. Attempts to obtain the X-ray crystal structure of 3
have not been successful. Layering n-hexane on top of a
benzene solution of 3 gave diffraction-quality crystals of 4.
Standing a solution of 3 in anhydrous n-hexane at RT over days
produced [RuII(2,6-F2-TPP)(NH2Ad)2] (5). Complex 4, and
isostructural [RuVI(Por)(NAd)(O)] (Por = 2,6-Cl2-TPP: 6, TMP: 7),
could also be prepared through aerobic oxidative deprotonation of
[RuII(Por)(NH2Ad)2] (Scheme 1).
a. Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The
University of Hong Kong, Pokfulam Road, Hong Kong, China. E-mail:
cmche@hku.hk
Complexes 2‒7 were characterised by spectroscopies (see
the ESI†) and, for 2, 4, 5, also by X-ray crystallography (Fig. S1,
ESI†; Fig. 1 and 2). The H NMR spectra of diamagnetic Ru(VI)-
alkylimido complexes 3 and 4 exhibit pyrrolic signals (Hβ: 8.70
and 8.91 ppm for 3 and 4, respectively) that are downfield
b.HKU Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong
518057, China
†
Electronic supplementary information (ESI) available: Abbreviations,
1
experimental procedures, compound characterisation, Tables S1–S2, Fig. S1–S4
and computational details. CCDC 1972136, 1985960 and 1972138. For ESI and
crystallographic data in CIF or other electronic format see DOI:
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 4
COMMUNICATION
Journal Name
shifted from that of diamagnetic Ru(II)-alkylamine complex 5
(Hβ: 8.34 ppm). The Hβ signal of 3 is slightly upfield shifted from
that of 4, as the former has one extra alkylimido ligand that is
more π-basic than the oxo ligand.5,7 These spectral features are
View Article Online
DOI: 10.1039/C9CC09972G
F1
C23
F4
N3
Ru
F3
F2
7b
reminiscent of those reported for [RuVI(4-Cl-TPP)(NBut)2] (not
N1
N2
N2
N1
isolated,
due
to
extreme
moisture
sensitivity),
F2
[RuVI(Por)(NBut)(O)] and [RuII(Por)(NH2But2)].7 In the case of 19F
NMR spectra, 3 exhibits a single signal at ‒108.1 ppm whereas 4
shows two signals at ‒105.8 and ‒108.7 ppm, consistent with
their molecular symmetry. The MALDI-TOF MS spectra of both 3
and 4 display peaks at m/z 1007.1817 attributable to [Ru(2,6-F2-
TPP)(NAd)] fragment. In the UV-vis spectrum of 3 (Fig. 3), split
Soret bands appear at 410 and 417 nm, which could be
originated from two close-lying transitions (π-π*(Por) and π-
π*(Ru=NC(Ad))) caused by two bent NAd ligands according to
DFT calculations (Fig. S3 and S4, ESI†). Analogous Ru(VI)-
bis(imido) porphyrins, such as [RuVI(Por)(NSO2Ar)2] (Por = TPP,
TTP, 4-Cl-TPP, TMP, 2,6-Cl2-TPP, F20-TPP), also exhibit Soret
bands in similar spectral region (413–423 nm) in CH2Cl2.4b,d The
UV-vis spectrum of 4 (Fig. 3) shows a Soret band at 411 nm
significantly red-shifted from that of the Ru(II) precursor 2 (at
405 nm), as the (dxy)2(dπ)0 electronic structure of 4 is deprived of
dπ(Ru)-π*(Por) back donation, which narrows the π-π*(Por)
energy gap.8 On going from 2 to the Ru(VI) complex 4, the β
band exhibits a large red shift (from 503 to 553 nm), in accord
with other Ru(VI) porphyrins displaying β bands well red-shifted
from those of Ru(II) counterparts.4d,7b,9 The key spectral features
of 6 and 7 (see the ESI†) are similar to that of 4 (e.g. the three
complexes all exhibited oxidation state marker band at 1014 cm-
1 in IR spectra and parent-ion peak in HRMS analysis).
'
F3
N3
F1
F4
Fig. 2 ORTEP drawing of 5 (thermal ellipsoids drawn at 30% probability level).
Hydrogen atoms are omitted. Selected bond distances (Å) and angles (°): Ru‒N1
2.045(4), Ru‒N2 2.028(4), Ru‒N3 2.158(4), N3‒C23 1.503(7); N3-Ru-N3 : 180.0(3), N1-Ru-
’
’
N3: 80.87(17), N1-Ru-N3 : 99.13(17), Ru-N3-C23: 132.4(4).
155000
4
3
105000
55000
5000
360
460
560
660
Wavelength (nm)
Fig. 3 UV-vis spectra of 3 and 4 in CH2Cl2.
The X-ray crystal structure of 4 (Fig. 1) features Ru=NAd
distance of 1.778(5) Å and Ru=O distance of 1.760(4) Å; the N5- (1.760(4) Å) compared with that of [RuVI(Por)(O)2] (ca. 1.72–
Ru-O1 and Ru-N5-C45 angles are 174.37(19)° and 167.7(4)°, 1.74 Å9,11), which is analogous to the longer Os-oxo bond in
respectively, revealing an almost linear axial Ru=N-C(Ad) [OsVI(TTP)(NBut)(O)] than in [OsVI(Por)(O)2] (1.772(7) vs
moiety. In contrast, the X-ray crystal structure of 5 (Fig. 2) 1.743(3) Å),5 is suggestive of the strong π-donor strength of
shows bent axial Ru-N-C(Ad) moieties (with an angle of NAd ligand. This finding is reflective of π-delocalisation
131.2(4)°), coupled with relatively long Ru‒N(NH2Ad) bonds between the metal-alkylimido and metal-oxo units in 4.
(2.158(4) Å), resembling the structure features of
We recorded the cyclic voltammograms of the
[RuII(TMP)(NH2Bn)2] (axial Ru-N-C(Bn) angle: 118.7(2)°, oxo(alkylimido) complexes 4, 6 and 7 and also the dioxo
Ru‒N(NH2Bn) 2.129(2) Å).10 The lengthened Ru-oxo bond of 4 counterpart [RuVI(2,6-F2-TPP)(O)2] (Fig. 4). Notably, the 1st
reduction potential Ep,c of 4 is ‒1.52 V (vs Fc+/Fc), which is
cathodically shifted by 740 mV compared with that of
[RuVI(2,6-F2-TPP)(O)2] (‒0.78 V), revealing that substitution of
F2
the oxo ligand with alkylimido (NAd) ligand has a significant
effect on this redox process and suggesting that the alkylimido
ligand is a much stronger π-base. A less significant effect was
C45
N5
F8
F3
observed by changing the porphyrinato ligand in
N4
F6
[RuVI(Por)(NAd)(O)], as is evident from the similar 1st reduction
potential Ep,c of ‒1.52, ‒1.53, and ‒1.69 V for Por = 2,6-F2-TPP
(in 4), 2,6-Cl2-TPP (in 6), and TMP (in 7), respectively. This is
consistent with the metal-centred Ru(VI) to Ru(V) reduction.
DFT calculations were conducted on 3 and 4 to gain insight
into their electronic structures. The optimised structure of 4
shows consistence with the crystal structure (Fig. S2, ESI†). It
can be noted that hyper-conjugation effect of the Ad group
destabilises π*(O-Ru-NAd) orbital (Fig. 5), which is conceived to
be responsible for the diminished reactivity of 4 compared
N1
Ru
N3
F1
N2
F7
O1
F4
F5
Fig. 1 ORTEP drawing of 4 (thermal ellipsoids drawn at 30% probability level).
Hydrogen atoms are omitted. Selected bond distances (Å) and angles (o): Ru‒N1
2.070(4), Ru‒N2 2.065(4), Ru‒N3 2.071(4), Ru‒N4 2.080(4), Ru‒N5 1.778(5), Ru‒O1
1.760(4), N5-C45 1.416(7); N5-Ru-O1: 174.37(19), N1-Ru-N5: 91.82(18), N1-Ru-O1:
92.00(17), Ru-N5-C45: 167.7(4).
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 4
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
View Article Online
DOI: 10.1039/C9CC09972G
 orbital destabilised by
hyper-conjugation
4
(
)
[RuVI(Por)(O)2] typically undergo HAA and radical rebound
Fig. 5 DFT-calculated molecular orbitals of 4 and [RuVI(2,6-F2-TPP(O)2].
Fig. 4 Cyclic voltammograms recorded in CH2Cl2 with 0.1 M [nBu4N]PF6.
with [RuVI(2,6-F2-TPP)(O)2] towards reduction. On the other
hand, the calculated Ru=NAd bond distance and Ru-N-C(Ad)
angle in 3 are 1.79 Å and 156.9°, respectively (Fig. 6). The MO
diagram of 3 shows that its π orbitals are at higher energies
than that in 4 (ca. +1.0 eV), suggesting that the higher basicity
of NAd in 3 causes a greater susceptibility to protonation.
We examined the stoichiometric reactions of the alkylimido
complexes 3 and 4 with styrene (Scheme 2). Complex 4 reacted
with styrene at 80 °C to give epoxidation product, but neither 3
nor 4 was reactive towards aziridination of styrene,12 unlike the
sulfonyl- and arylimido complexes [RuVI(Por)(NSO2Ar)2] and
[RuVI(Por)(NAr)2] which can undergo alkene aziridination
reactions.4b,d,h The higher reactivity of the sulfonyl- and
arylimido complexes can be attributed to the elevated
electrophilicity resulting from π-delocalisation between the
Nimido and SO2Ar/Ar groups and higher one-electron reduction
potential (e.g., E1/2 = ‒0.34 and ‒0.27 V vs. Fc+/Fc for [RuVI(2,6-
Cl2-TPP)(NTs)2] and [RuVI(TPP)(NTs)2], respectively4d); sterics
might also play a role due to less bulky SO2Ar/Ar groups than
adamantyl group. The Nimido‒CAr and Nimido‒STs bonds in
[RuVI(TPP)(NAr)2] (Ar = 3-(CF3)2-C6H3) and [RuVI(TMP)(NMs)2]
were reported to be 1.361(6)4f and 1.60(2) Å,4g respectively, and
these values are in between those of N‒C(sp2) and N=C(sp2) (ca.
1.28–1.42 Å) or N‒S(sp3) and N=S(sp3) (ca. 1.53–1.73 Å).
.
Fig. 6 DFT-optimised structure of 3 and comparison of its molecular orbitals with 4.
NAd
3
(1)
PhH, 80 oC,
overnight under Ar
not observed
O
4
PhH, 80 oC,
(2)
(3)
(4)
overnight under Ar
>99% yield
3
or
or
CD2Cl2, RT,
overnight under Ar
>99% yield
4
CD2Cl2, RT,
overnight under Ar
92% yield
Interestingly, complexes 3 and 4 can undergo hydrogen
atom abstraction (HAA) reaction with allylic or benzylic
hydrocarbons to give 5 bearing coordinated amine ligands,
and, for the reaction of 3 (bearing two alkylimido axial ligands)
Scheme 2 Reactivity studies involving 3 and 4. Yield: based on [product]/[Ru] (see ESI†).
mechanism to give C‒H bond hydroxylation products.
with
cyclohexa-1,4-diene/9,10-dihydroanthracene,
a
Despite the fact that aerobic epoxidation can be mediated
by a cycle involving [RuIV(Por)(O)] and [RuII(Por)],13 exploring
other new ruthenium porphyrin systems capable of mediating
aerobic epoxidation is of considerable interest. We found that
[RuVI(Por)(NAd)(O)] can mediate epoxidation of a variety of
alkenes under aerobic conditions (Table 1), albeit with
quantitative yield of benzene/anthracene (2 equiv. generated
per Ru used) was observed as the organic product, respectively
(Scheme 2). The reaction of 4 (bearing one alkylimido axial
ligand) with 9,10-dihydroanthracene gave anthracene with a
yield of 92%. For both 3 and 4, no oxygen atom transfer
reaction
with
the
hydrocarbons was observed, whereas the dioxo complexes
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 4
COMMUNICATION
Journal Name
Tiekink, W. B. Breukerlaar, D. L. J. Broere, N. P. van Leest, J. I.
attenuated reactivity. Complex 4 could mediate aerobic
epoxidation of cyclohexene, norbornene, and styrenes at RT;
View Article Online
van der Vlugt, J. N. H. Reek and B. dDeOBI:r1u0i.n10, 3C9h/Cem9C.C–0E9u9r7. 2JG.,
2017, 23, 7945; (g) Z. Lin, N. C. Thacker, T. Sawano, T. Drake,
P. Ji, G. Lan, L. Cao, S. Liu, C. Wang and W. Lin, Chem. Sci.,
2018, 9, 143; (h) M. Goswami, P. Geuijen, J. N. H. Reek and B.
de Bruin, Eur. J. Inorg. Chem., 2018, 617.
Table 1 Aerobic oxidations of alkenes mediated by [RuVI(Por)(NAd)(O)] (4, 6, 7).i
O2 (1 atm)
O
catalyst (1 mol%)
2
3
(a) Y. M. Badiei, A. Dinescu, X. Dai, R. M. Palomino, F. W.
Heinemann, T. R. Cundari and T. H. Warren, Angew. Chem. Int.
Ed., 2008, 47, 9961; (b) S. Wiese, Y. M. Badiei, R. T. Gephart, S.
Mossin, M. S. Varonka, M. M. Melzer, K. Meyer, T. R. Cundari
and T. H. Warren, Angew. Chem. Int. Ed., 2010, 49, 8850; (c) E.
R. King, E. T. Hennessy and T. A. Betley, J. Am. Chem. Soc.,
2011, 133, 4917; (d) M. J. B. Aguila, Y. M. Badiei and T. H.
Warren, J. Am. Chem. Soc., 2013, 135, 9399; (e) K. Shin, Y.
Baek and S. Chang, Angew. Chem. Int. Ed., 2013, 52, 8031.
For examples, see: (a) X. Hu and K. Meyer, J. Am. Chem. Soc.,
2004, 126, 16322; (b) D. T. Shay, G. P. A. Yap, L. N. Zakharov, A.
L. Rheingold and K. H. Theopold, Angew. Chem. Int. Ed., 2005,
44, 1508; (c) C. M. Thomas, N. P. Mankad and J. C. Peters, J.
Am. Chem. Soc., 2006, 128, 4956; (d) I. Nieto, F. Ding, R. P.
Bontchev, H. Wang and J. M. Smith, J. Am. Chem. Soc., 2008,
130, 2716; (e) R. E. Cowley, N. A. Ecker, S. Vaddadi, T. M. Figg,
T. R. Cundari and P. L. Holland, J. Am. Chem. Soc., 2011, 133,
9796; (f) A. M. Geer, C. Tejel, J. A. López and M. A. Ciriano,
Angew. Chem. Int. Ed., 2014, 53, 5614.
For examples, see: (a) W.-H. Leung, T. S. M. Hun, H.-w. Hou
and K.-Y. Wong, J. Chem. Soc., Dalton Trans., 1997, 237; (b)
S.-M. Au, J.-S. Huang, W.-Y. Yu, W.-H. Fung and C.-M. Che, J.
Am. Chem. Soc., 1999, 121, 9120; (c) R. A. Eikey, S. I. Khan
and M. M. Abu-Omar, Angew. Chem. Int. Ed., 2002, 41, 3592;
(d) S. K.-Y. Leung, W.-M. Tsui, J.-S. Huang, C.-M. Che, J.-L.
Liang and N. Zhu, J. Am. Chem. Soc., 2005, 127, 16629; (e) S.
Fantauzzi, E. Gallo, A. Gaselli, F. Ragaini, N. Casati, P. Macchi
and S. Cenini, Chem. Commun., 2009, 3952; (f) D. Intrieri, A.
Caselli, F. Ragaini, P. Macchi, N. Casati and E. Gallo, Eur. J.
Inorg. Chem., 2012, 569; (g) Z. Guo, X. Guan, J.-S. Huang, W.-
M. Tsui, Z. Lin and C.-M. Che, Chem.–Eur. J., 2013, 19, 11320;
(h) S.-M. Law, D. Chen, S. L.-F. Chan, X. Guan, W.-M. Tsui, J.-
S. Huang, N. Zhu and C.-M. Che, Chem.–Eur. J., 2014, 20,
11035; (i) S. Hong, K. D. Sutherlin, A. K. Vardhaman, J. J. Yan,
S. Park, Y.-M. Lee, S. Jang, X. Lu, T. Ohta, T. Ogura, E. I.
Solomon and W. Nam, J. Am. Chem. Soc., 2017, 139, 8800.
Z.-Y. Li, J.-S. Huang, M. C.-W. Chan, K.-K. Cheung and C.-M.
Che, Inorg. Chem., 1997, 36, 3064.
CD2Cl2 or C6D6
RT, 24 h
Product(s) (equiv. per Ru)
Catalyst
Substrate
Entry
a
(3)
O
4
(5)
O
4
4
b
c
O
O
O
H
X
X
X = H
X
X
(<1)
(<1)
(4)
(4)
(1)
X = tBu
d
4
4
(2)
(8) or (8)iii
eii
X = NO2
O
f
(1)
6
7
X = NO2
X = NO2
O2N
(5) or (5)iv
g
i
Conditions: substrate (0.2 mmol), catalyst (0.002 mmol) and solvent (CD2Cl2, 2
mL). ii 40 oC. iii 5 atm O2. iv C6D6 as solvent.
4
better product yield was found for the epoxidation of p-
nitrostyrene at 40 oC (8 equiv. epoxide product per complex 4,
entry e in Table 1; no other oxidation products were detected).
In the cases of electron-rich styrenes such as p-(tert-
butyl)styrene, besides epoxides, benzaldehydes and
phenylacetaldehydes were also formed (entry d in Table 1).
In summary, [RuVI(2,6-F2-TPP)(NAd)(O)] (4), which was both
spectroscopically and crystallographically characterised, is
capable of undergoing oxygen atom transfer (but not
alkylimido group transfer) to styrene, and can also mediate
aerobic epoxidation of alkenes. Electrochemical studies
showed that the first reduction of 4 is less thermodynamically
favourable compared with the dioxo counterpart [RuVI(2,6-F2-
TPP)(O)2]. [RuVI(2,6-F2-TPP)(NAd)2] (3) is unable to transfer its
alkylimido group(s) to styrene, but can undergo HAA reactions
with cyclohexa-1,4-diene or dihydroanthracene to give
[RuII(2,6-F2-TPP)(NH2Ad)2] (5) and benzene or anthracene.
We gratefully acknowledge the financial support from
Hong Kong Research Grants Council (HKU 17301817) and Basic
Research Program-Shenzhen Fund (JCYJ20170412140251576
and JCYJ20180508162429786).
5
6
7
K.-P. Shing, B. Cao, Y. Liu, H. K. Lee, M.-D. Li, D. L. Phillips, X.-
Y. Chang and C.-M. Che, J. Am. Chem. Soc., 2018, 140, 7032.
(a) J.-S. Huang, C.-M. Che and C.-K. Poon, J. Chem. Soc., Chem.
Commun., 1992, 161; (b) J.-S. Huang, X.-R. Sun, S. K.-Y. Leung,
K-K. Cheung and C.-M. Che, Chem.–Eur. J., 2000, 6, 334.
A. Antipas, J. W. Buchler, M. Gouterman and P. D. Smith, J.
Am. Chem. Soc., 1978, 100, 3015.
C.-M. Che, J.-L. Zhang, R. Zhang, J.-S. Huang, T.-S. Lai, W.-M.
Tsui, X.-G. Zhou, Z.-Y. Zhou, N. Zhu and C. K. Chang, Chem.–
Eur. J., 2005, 11, 7040.
8
9
Conflicts of Interest
10 A. J. Bailey and B. R. James, Chem. Commun., 1996, 2343.
11 (a) T.-S. Lai, R. Zhang, K.-K. Cheung, H.-L. Kwong and C.-M.
Che, Chem. Commun., 1998, 1583; (b) E. Gallo, A. Caselli, F.
Ragaini, S. Fantauzzi, N. Masciocchi, A. Sironi and S. Cenini,
Inorg. Chem., 2005, 44, 2039.
There are no conflicts to declare.
Notes and references
1
(a) E. T. Hennessy and T. A. Betley, Science, 2013, 340, 591;
(b) D. L. J. Broere, B. de Bruin, J. N. H. Reek, M. Lutz, S.
Dechert and J. I. van der Vlugt, J. Am. Chem. Soc., 2014, 136,
11574; (c) N. C. Thacker, Z. Lin, T. Zhang, J. C. Gilhula, C. W.
Abney and W. Lin, J. Am. Chem. Soc., 2016, 138, 3501; (d) B.
Bagh, D. L. Broere, V. Sinha, P. F. Kuijpers, N. P. van Leest, B.
de Bruin, S. Demeshko, M. A. Siegler and J. I. van der Vlugt, J.
Am. Chem. Soc., 2017, 139, 5117; (e) H. Kim and S. Chang,
Angew. Chem. Int. Ed., 2017, 56, 3344; (f) P. F. Kuijpers, M. J.,
12 Approximately 30–40% of 3 or 4 (based on the integration of
1
their pyrrolic H NMR signals) was converted into 5 after
stoichiometric reaction with styrene.
13 For examples, see: (a) J. T. Groves and R. Quinn, J. Am. Chem.
Soc., 1985, 107, 5790; (b) J. T. Groves and K.-H. Ahn, Inorg.
Chem., 1987, 26, 3831.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins