Preparation and reactivity of half-sandwich dioxygen complexes of ruthenium

Article abstract of DOI:10.1039/c8dt01871e

Dioxygen complexes [Ru(η⁵-C₅Me₅)(η²-O₂){P(OEt)₃}₂]BPh₄ (1) and [Ru(η⁵-C₅Me₅)(η²-O₂)(PPh₃){P(OR)₃}]BPh₄ (2, 3) [R = Me (2), Et (3)] were prepared by allowing chloro-complexes RuCl(η⁵-C₅Me₅)[P(OEt)₃]₂ and RuCl(η⁵-C₅Me₅)(PPh₃)[P(OR)₃] to react with air (1 atm) in the presence of NaBPh₄. Substitution of the η²-O₂ in 1-3 by alkenes [CH₂CH₂, CHCHCO(O)CO] and terminal alkynes (PhCCH) afforded [Ru(η⁵-C₅Me₅)(η²-CH₂CH₂){P(OEt)₃}L]BPh₄ (4) [L = P(OEt)₃ (a), PPh₃ (b)], [Ru(η⁵-C₅Me₅){η²-CHCHCO(O)CO}{P(OEt)₃}₂]BPh₄ (5) and [Ru(η⁵-C₅Me₅){CC(H)Ph}{P(OEt)₃}₂]BPh₄ (6) derivatives. Protonation of dioxygen complexes 1-3 with triflic acid yielded phosphate complexes [Ru(κ¹-OTf)(η⁵-C₅Me₅){P(O)(OEt)₃}₂] (7) and [Ru(κ¹-OTf)(η⁵-C₅Me₅){P(O)Ph₃}{P(O)(OMe)₃}] (8). A reaction path for the formation of complexes 7 and 8 is proposed by DFT studies. Besides phosphate complex 7, protonation of 1 under a CH₂CH₂ atmosphere (1 atm) afforded acetic acid. Treatment of complexes 7 and 8 with ^tBuNC afforded the tris(isocyanide) derivative [Ru(η⁵-C₅Me₅)(^tBuNC)₃]BPh₄ (9). The complexes were characterised spectroscopically (IR and NMR) and by X-ray crystal structure determination of 1, 2 and 3.

Full text of DOI:10.1039/c8dt01871e

Dalton
Transactions
View Article Online
View Journal
PAPER
Preparation and reactivity of half-sandwich
dioxygen complexes of ruthenium†
Cite this: DOI: 10.1039/c8dt01871e
a
a
a
Gabriele Albertin, * Stefano Antoniutti,
Jesús Castro
Marco Bortoluzzi,
b
a
and Valentina Ferraro
5
2
5
2
Dioxygen complexes [Ru(η -C
5
Me
5
)(η -O
2
){P(OEt)
3
}
2
]BPh
4
(1) and [Ru(η -C
5
Me
5
5
)(η -O
2
)(PPh
3 3
){P(OR) }]
BPh
4
(2, 3) [R = Me (2), Et (3)] were prepared by allowing chloro-complexes RuCl(η -C
5
Me
5
)[P(OEt)
3
]
2
and
2
5
RuCl(η -C
5
Me
5
)(PPh
3
)[P(OR)
3
] to react with air (1 atm) in the presence of NaBPh
4
. Substitution of the η -
5
O
2
in 1–3 by alkenes [CH
2
vCH
2
, CHvCHCO(O)CO] and terminal alkynes (PhCuCH) afforded [Ru(η -
2
5
2
C
5
Me
P(OEt)
gen complexes 1–3 with triflic acid yielded phosphate complexes [Ru(κ -OTf)(η -C
5
)(η -CH
2
vCH
2
){P(OEt)
3
5
}L]BPh
4
(4) [L = P(OEt)
3
(a), PPh
3
(b)], [Ru(η -C
]BPh (6) derivatives. Protonation of dioxy-
5 5
Me ){η -CHvCHCO(O)CO}
{
3
}
2
]BPh
4
(5) and [Ru(η -C
5
Me
5
){vCvC(H)Ph}{P(OEt)
3
}
2
4
1
5
5
Me
5 3 2
){P(O)(OEt) } ] (7)
1
5
and [Ru(κ -OTf)(η -C Me ){P(O)Ph }{P(O)(OMe) }] (8). A reaction path for the formation of complexes 7
5 5 3 3
Received 9th May 2018,
Accepted 19th June 2018
and 8 is proposed by DFT studies. Besides phosphate complex 7, protonation of 1 under a CH vCH2
2
t
atmosphere (1 atm) afforded acetic acid. Treatment of complexes 7 and 8 with BuNC afforded the tris
DOI: 10.1039/c8dt01871e
5
t
(
isocyanide) derivative [Ru(η -C
5 5 3 4
Me )( BuNC) ]BPh (9). The complexes were characterised spectroscopi-
rsc.li/dalton
cally (IR and NMR) and by X-ray crystal structure determination of 1, 2 and 3.
We are interested in the chemistry of half-sandwich com-
plexes of ruthenium with phosphite ligands and have recently
Introduction
8
9
,10
The activation of dioxygen by transition metal fragments has reported
that the cyclopentadienyl and pentamethyl-
5
+
attracted considerable attention in recent decades because of cyclopentadienyl fragments [Ru(η -C H )(PPh ){P(OR) }] and
5
5
3
3
1
5
+
its relevance to biological oxidation reactions and interest for [Ru(η -C
5
Me
5 3 3 3
)(L){P(OR) }] [L = PPh , P(OR) ] show interesting
2
its application in industrial processes. Although the latter properties in the activation of coordinate diazoalkane towards
9
10
often exploit partially-reduced forms of O , such as peroxides both (3 + 2) cycloaddition and hydrolysis reactions. These
2
2
or oxo-complexes, nature operates with the most readily-avail- results prompted us to extend our studies on half-sandwich
6
2
able oxidant, i.e., dioxygen, using metal complexes having a d
configuration as catalysts.
complexes to dioxygen in order to test whether η -O complexes
2
3
may form and how these fragments may activate this impor-
In this context, a number of transition metal complexes tant molecule. The results of these studies are reported here.
2
4,5
containing dioxygen as a ligand (η -O ) were prepared and
2
4
,5
some studies on the oxygen transfer reaction reported. The
principal type involves the iron triad as a central metal with
bidentate phosphine or cyclopentadienyl as supporting
Results and discussion
2
2
4
g–o,q,5a,d,i
Preparation of η -O derivatives
ligands.
The activation of dioxygen by these frag-
5
ments often involves the formation of oxo complexes [M]vO Dioxygen complexes of ruthenium of the types [Ru(η -C Me )
5
5
3
,4k,n
6
2
5
2
as intermediates,
relevant in olefin epoxidation and (η -O ){P(OEt) } ]BPh (1) and [Ru(η -C Me )(η -O )(PPh ){P
2
3 2
4
5
5
2
3
7
alkene hydroxylation reaction. Examples of intramolecular (OR) }]BPh (2, 3) [R = Me (2), Et (3)] were prepared by allowing
3
4
4
b,l,i
5
5
dioxygen transfer to organic substrates are also reported.
either the chloro-complex RuCl(η -C Me )[P(OEt) ] or RuCl(η -
5
5
3 2
5 5 3 3
C Me )(PPh )[P(OR) ] to stir under air (1 atm) in the presence
of NaBPh , as shown in Scheme 1.
4
a
The reaction proceeds with substituting the Cl− ligand and
Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia,
Via Torino 155, 30172 Venezia Mestre, Italy. E-mail: albertin@unive.it
forming dioxygen complexes 1–3, which were separated as
b
Departamento de Química Inorgánica, Universidade de Vigo, Facultade de Química,
BPh salts and characterised. Crucial for successful syntheses
4
Edificio de Ciencias Experimentais, 36310 Vigo, Galicia, Spain
4
was the presence of the salt NaBPh , which, favoured the sub-
†
Electronic supplementary information (ESI) available. CCDC 1842088–1842090.
For ESI and crystallographic data in CIF or other electronic format see DOI:
0.1039/c8dt01871e
−
stitution of the Cl ligand and allowed the complexes to separ-
ate as solids in good yields.
1
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
2
mentioned phosphine ligands and a dioxygen ligand in a η
coordination manner, also called side-on behaviour. The
overall geometry of the complex is pseudo octahedral, where
three of the positions are occupied by the Cp* ligand and the
dioxygen donor ligand occupies only one of the coordination
sites. In this way, the angles between the legs (see Table 1) are
near 90°. The P–Ru–P angles are between 85.207(12)° and
88.024(13)°, and the other angles to be considered are those
between the centre of the O–O bond and the phosphorus
atom, P–Ru–Ct2 angles. These, probably due to sterical
reasons, are bigger, between 95.639(10)° and 101.837(11)°. The
Ru–P bond lengths depends on the nature of the ligand, with
values around 2.28 Å for phosphite ligands and about 2.37 Å
for triphenylphosphine ligands. Coordination of the Cp*
ligand also shows the small differences depending on the
phosphorus ligands, so the Ru–C bond average is about 2.27 Å
and for mixed ligands and slightly shorter for the diphosphite
Scheme 1 R = Me (2), Et (3).
5
+
5 5 3 2
Both the bis(phosphite) [Ru(η -C Me ){P(OEt) } ]
5
+
mixed-ligand [Ru(η -C Me )(PPh ){P(OR) }] fragments were compound. It is worth noting that these parameters are very
5
5
3
3
able to coordinate the dioxygen molecule, affording yellow- similar to those found in other Ru(II) compounds previously
1
0b,c
orange solids 1–3, stable in air and in solution of polar organic described by our group.
solvents, where they behaved as 1 : 1 electrolytes.
The dioxygen ligand is situated in
1
1
a side-on mode, with Ru–O bond distances between 2.0207(9)
Analytical and spectroscopic data (IR and NMR) confirmed and 2.2939(4) Å. However, the distance between the metal
the proposed formulation, which was further supported by atom and the middle of the O–O bond (Ru–Ct2 entry in
5
2
X-ray crystal structure determination of [Ru(η -C Me )(η -O ){P Table 1) does not depend on the ancillary ligand. The O–O
5
5
2
5
2
(
OEt)
3
}
2
]BPh
4
(1), [Ru(η -C
5
Me
5
)(η -O
2
)(PPh
3
){P(OMe)
3
}]BPh
4
bond distance is between 1.401(3) and 1.4104(13) Å. These
5
2
(
2) and [Ru(η -C
5
Me
5
)(η -O
2
)(PPh
3
){P(OEt)
3
}]BPh
4
(3).
features have also been found in several similar compound
The three complexes consist of tetraphenylborate salts of with the Cp*Ru(O
ruthenium complexes. Only the corresponding cation of 2 is are different phosphorus donors.
2
)P1P2 moiety previously, where P1 and P2
4
i,l,o,s,t,5d,13–15
Worthy of
shown in Fig. 1. This is because the other compounds differ note is that, in literature, the compounds are discussed as
only in phosphorus donors, i.e., 1 contains two phosphite formally Ru(IV)-peroxo complexes, since the O–O bond distance
ligands P(OEt)
ligand.
3
and 3 contains one P(OEt)
3
and one PPh
3
is in the middle of the wide range found in classical peroxo
compounds such as potassium peroxide or hydrogen
In all cases, the cation complex contains a ruthenium atom peroxide.
in a half-sandwich piano-stool structure, coordinated by a
pentamethylcyclopentadienide group (Cp*), the two above-
4
t
Table 1 Selected bond lengths [Å] and angles [°]
1
2
3
Ru–CT1
Ru–CT2
Ru–O(1)
Ru–O(2)
Ru–P(1)
Ru–P(2)
Ru–C(1)
Ru–C(2)
Ru–C(3)
Ru–C(4)
Ru–C(5)
Ru–Cav
1.89329(17)
1.90535(14)
2.0342(9)
2.0270(9)
2.2801(4)
2.2752(3)
2.2553(12)
2.2845(12)
2.2839(13)
2.2469(12)
2.2126(12)
2.2568
1.9132(3)
1.9039(2)
2.0366(17)
2.0211(17)
2.2895(6)
2.3752(6)
2.252(2)
2.229(2)
2.236(2)
2.296(2)
2.316(2)
2.266
1.9140(6)
1.9041(7)
2.0207(9)
2.0404(9)
2.2939(4)
2.3727(4)
2.2428(13)
2.3025(13)
2.3092(13)
2.2636(13)
2.2325(13)
2.2701
O(1)–O(2)
1.4045(13)
1.401(3)
1.4104(13)
CT1–Ru–CT2
CT1–Ru–P(1)
CT1–Ru–P(2)
CT2–Ru–P(1)
CT2–Ru–P(2)
P(1)–Ru–P(2)
125.021(6)
119.886(9)
124.527(10)
95.639(10)
94.595(10)
88.024(13)
121.110(10)
119.976(18)
128.638(16)
100.642(19)
91.830(16)
86.22(2)
120.182(7)
119.992(11)
129.292(10)
101.837(11)
92.125(10)
85.207(12)
1
2
5
2
Fig. 1 ORTEP view of the cation in the compound [Ru(η -C
)(PPh ){P(OMe) }]BPh (2).
5
Me
5
)(η - CT1 is the centroid of the Cp* ligand. CT2 is the centroid of the O2
O
2
3
3
4
ligand.
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
In the IR spectrum of 1 a weak band assignable to νO–O was Reactivity
−
1
observed at 935 cm , which is absent in the spectrum of the
5
precursor RuCl(η -C
and 3 this νO–O band is not unambiguously assignable.
The proton NMR spectra of dioxygen complexes 1–3 show the transfer of dioxygen to the organic substrate is possible.
5
Me
5
)[P(OEt)
3
]
2
. In the related complexes 2 Reactivity studies of our dioxygen complexes 1–3 with alkenes
and alkynes were undertaken with the aim of testing whether
5
the signals of the η -C
either a triplet (1) or a doublet (2, 3), owing to coupling with not react with alkene [CH
the P nuclei of P(OR) phosphites. The characteristic signals of (PhCuCH), leaving the starting complexes unchanged after 48 h
, phosphites and of the BPh
appear in the spectra, whereas the P NMR spectra are a substituted, affording η -alkene [Ru(η -C
singlet for 1 and an AX quartet for 2 and 3, fitting the pro- {P(OEt) }L]BPh
posed formulation for the dioxygen derivatives.
DFT calculations on the cation [Ru(η -C
OMe) } ] support the idea that these compounds are better characterised (Scheme 2).
5
Me
5
ligand methyl substituents as The results show that, at room temperature, complexes 1–3 do
2
vCH , CHvCHCO(O)CO] and alkyne
2
3
–
2
phosphine PPh
3
4
anion also of reaction. Instead, in refluxing 1,2-dichloroethane, η -O
2
was
2
)
3
1
2
5
2
5
2
Me
5
)(η -CH
2
vCH
5
(4),
[Ru(η -C Me ){η -CHvCHCO(O)CO}
Me ){vCvC(H)
5 5
(6) derivatives, which can be isolated and
3
4
5
5
5
{P(OEt)
){P Ph}{P(OEt)
3
}
2
]BPh
4
(5) and vinylidene [Ru(η -C
5
2
5
Me
5
)(η -O
2
3
}
2
]BPh
4
+
(
3
2
described as Ru(IV) peroxo-complexes rather than Ru(II) dioxy-
gen derivatives. Both the π* orbitals of coordinated [O ] are η -O
doubly occupied, that of the highest-energy (HOMO) behaving evidence of oxidation products was detected in the reaction
as non-bonding with respect to [Ru–O ] interaction. Instead, mixture, but only in the excess of organic reagents.
the other π* orbital is involved in σ-interactions with the metal
centre, mainly described by HOMO−2 and HOMO−7 orbitals. oxygen-transfer reactions prompted us to study the behaviour
The reaction seems to only involve the substitution of the
2
ligand by the unsaturated organic substrate, because no
2
2
2
2
2
The stability of the η -O ligand and the related absence of
2
The interaction of the [O
2
] fragment with ruthenium is sup- of the η -O
π-orbitals with those began with the reaction of 1–3 with HOTf at low temperature,
of the [Ru(η -C Me ){P(OMe) } ] cation as is observable, for adding increasing amounts of acid to a CD Cl solution and
2
species in the presence of Brønsted acids. We
ported by the overlap of the occupied O
2
5
+
5
5
3 2
2
2
instance, in HOMO−36, HOMO−38 and HOMO−42 MOs monitoring the progress of the reaction by NMR spectra. The
5
2
(
Fig. 2). The negative Hirshfeld charge on coordinated [O
2
], results showed that adding HOTf to [Ru(η -C
5
Me
5
2
)(η -O ){P
−
0.39 a.u., is in agreement with the formal formation of (OEt) } ]BPh (1) caused the disappearance of the singlet at
3
2
4
peroxo-derivatives. It is worth noting that the Hirshfeld charge 117.0 ppm of the P(OEt)
3
3
and the appearance of a new singlet
1
on the metal centre, 0.29 a.u., is quite similar to the value cal- at −2.77 ppm in the P spectrum, attributed to the co-
5
culated for the Ru(II) bis-organophosphate derivative [Ru(η - ordinated triethylphosphate P(O)(OEt) of a new species that
3
+
C
5
Me
5
){P(O)(OMe)
3
}
2
] , 0.32 a.u. (vide infra), highlighting that was formed. Apart from the signals of the starting complex 1
formal changes in the oxidation state of the ruthenium centre and of the phosphate, no other signals appeared both in the
1
31
are compensated by the ancillary ligands.
H and P NMR spectra, preventing the identification of other
5
2
+
Fig. 2 Selected occupied MOs of [Ru(η -C
5
Me
5
)(η -O
2
){P(OMe)
3
}
2
] . C-PCM/ωB97X calculations. Hydrogen atoms are omitted for clarity. Surface
isovalue = 0.04 a.u.
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
1
5
to the metal centre, affording the [Ru(κ -OTf)(η -C
5
Me
5
){P(O)
(
OEt) } ] (7) derivative.
3 2
5
2
The protonation reaction of [Ru(η -C
5
Me
5
)(η -O
2
2
){P
+
(
OEt)
3
}
2
] (1) in CD
2
Cl
2
was also tested with HBF
4
·Et
O and in
this case the NMR spectra also indicated the formation of the
phosphate P(O)(OEt) . Nonetheless, the complex obtained was
3
not stable and in few minutes decomposed releasing the phos-
phate. This different behaviour may still be explained on the
2
basis of an initial protonation of the η -O
2
, which promotes
3
the oxygen transfer to P(OEt) affording the phosphate species
P(O)(OEt) . However, the instability of the formed complex,
3
5
+
i.e., [Ru(η -C
poor coordinating properties of the BF
able to stabilise the species [Ru(κ -BF )(η -C Me ){P(O)(OEt) } ]
5
Me
5
){P(O)(OEt)
3
}
2
] , may be attributed to the
–
4
anion, which is not
1
5
4
5
5
3 2
which could be formed. Support for this hypothesis came
5
from the use of CF COOH, the reaction of which with [Ru(η -
3
2
+
C Me )(η -O ){P(OEt) } ] gave a stable oily product formulated
by NMR as [Ru(κ -OCOCF
5
5
2
3 2
1
5
3
)(η -C
5 5 3 2
Me ){P(O)(OEt) } ] (7′). The
use of a Brønsted acid containing a good coordinating anion
Scheme 2 L = P(OEt)
3
(a), PPh
3
(b).
−
−
(
OTf or CF COO ) allowed the stabilisation of the phosphate
3
complex 7 or 7′ which, unfortunately, can only be separated as
an oil.
5
2
intermediates. We attempted to isolate the formed complexes,
but only an oil was isolated, the NMR spectra of which agree {P(OMe)
with the presence of a bis(phosphate) complex of the type afford the phosphine oxide-phosphate compound of the type
Mixed-ligand dioxygen complex [Ru(η -C
5
Me
5
)(η -O
)(PPh )
2 3
3
}]BPh (2) also reacts in the presence of HOTf to
4
1
5
1
5
[
Ru(κ -OTf)(η -C Me ){P(O)(OEt) } ] (7) (Scheme 3).
[Ru(κ -OTf)(η -C Me ){P(O)Ph }{P(O)(OMe) }] (8) (Scheme 5).
5 5 3 3
5
5
3 2
The P(O)(OEt)
3
ligand can be removed from complex 7 by
Following the progress of the protonation reaction by
P NMR spectra, we observed the disappearance of the AX
quartet of the dioxygen precursor 2 and the appearance of
t
31
substitution with butylisocyanide (Scheme 4) and chromato-
graphic separation.
The NMR spectrum supports the proposed formulation two singlets at 30.5 and 0.47 ppm, attributed to phosphine
when compared with an authentic sample of P(O)(OEt)
oxide P(O)(Ph) and phosphate P(O)(OMe) , respectively,
3
,
3
3
suggesting the coordination of P(O)(OEt)3 in complex 7. On bonded to the central metal. The formation of phosphine
this basis, we can hypothesise that the acid promotes oxygen- oxide and phosphate from the oxidation of coordinated phos-
2
transfer to each phosphorus atom of the phosphite, affording phine by η -O
2
was confirmed by substituting both P(O)(Ph)
3
t
two phosphate molecules P(O)(OEt) , which can O-coordinate and P(O)(OMe)
groups from compound 8 with BuNC,
3
3
1
31
obtaining compound 9. The H and P NMR spectra con-
firmed the proposed formation of the species P(O)(Ph) and
3
P(O)(OMe)3 when compared with the spectra of authentic
samples. In addition, a comparison between the spectra
1
5
of [Ru(κ -OTf)(η -C
free phosphine oxide and phosphate suggested the
O-coordination of both P(O)(Ph ) and P(O)(OMe) species.
However, even at −90 °C, the P NMR spectra of 8 appear as
5 5 3 3
Me ){P(O)Ph }{P(O)(OMe) }] (8) and of
3
3
31
3
1
two singlets, indicating that the P coupling between the two
species P(O)(Ph)
3
3
and P(O)(OMe) , is so small as to result
Scheme 3
Scheme 4
Scheme 5
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
1
undetectable. It is probable that an exchange process still sketched in red in Scheme 6) less stable than I by about
occurs even at this temperature, preventing the detection of 15.8 kcal mol−
the expected P– P coupling.
1
.
3
1
31
The first oxygen transfer to one of the phosphine ligands
H⋯BF
(sketched in red in
and seems Scheme 6), or the non-protonated oxygen, with the formation
to involve hydroperoxide intermediates. A plausible mecha- of the hydroxo-intermediate I . This last possibility is more
nism for the intramolecular oxidation of coordinated phos- favourable from a thermodynamic point of view, being [Ru(η -
Acid-promoted oxygen transfer has been proposed for could involve the protonated oxygen atom of the [O
2
4
]
1
,4a,b,n,16
2
oxo
several peroxo complexes,
whereas intramolecular η -O
moiety, affording the oxo-complex I2
2
4
i,l
transfer to coordinate phosphine is very rare
2
5
5
+
phines is depicted in Scheme 6 (black path), where [Ru(η -
C
5
Me
are viewed as reactants than the oxo-species I
R). DFT C-PCM/ωB97X calculations allow to optimise possible the trimethylphosphate ligand dissociates as P(O)(OMe) ·HBF
5
)(OH⋯BF
4
){P(OMe)
3
}{P(O)(OMe)
3
}] (I
1
) more stable
by about 6.5 kcal mol . Moreover,
2
+
oxo
−1
C
5
Me
5
)(η -O
2
){P(OMe)
3
}
2
]
and HBF
4
2
(
3
4
oxo
intermediates of the reaction affording the corresponding bis from the oxo-intermediate I
phosphate) complex as the final product. in the hydroxo-complex I . In any case, the processes involving
Protonation of the coordinated [O ] fragment affording the the break of the O–O bond and the consequent formation of a
2
, while it remains coordinated
(
2
2
intermediate species I
Gibbs energy variation being −16.9 kcal mol−1. Such a result is −58.2 kcal mol where I
in agreement with the previously described peroxo-character Therefore, the relative slowness of the reaction (vide infra) is
1
is a favourable process, the associated PvO bond are characterised by high negative ΔG variations,
−1
2
is considered as an intermediate.
5
of the coordinated O
2
ligand. The compound [Ru(η -C
5
Me
5
)- probably associated to high-energy transition states. In fact,
2
+
(
η -O
2
H⋯BF
4
){P(OMe)
3
}
2
]
(I ) has singlet multiplicity. As DFT calculations for oxygen transfer carried out at EDF2 level
1
2
depicted in Scheme 6, the O -ligand keeps the η coordination permitted the finding of a coherent transition state geometry
2
mode after protonation, the computed Ru–OH bond length (TS, imaginary frequency = i569 cm− ) and the estimation of
1
being only 0.174 Å longer than the Ru–O one (2.188 and the energy barrier around 32 kcal mol−
1
.
2
.014 Å, respectively). The possible change of multiplicity
The formation of the second organophosphate ligand from
of the complex after protonation was ruled out, being
I
2
is another thermodynamically favourable process, the
5
2
+
t
−1
[Ru(η -C
5
Me
5
)(η -O
2
H⋯BF
4
){P(OMe)
3
}
2
]
in triplet state (I
1
,
associated ΔG being around −19.0 kcal mol . The product
5
2
+
5
Scheme 6 DFT-optimised intermediates proposed for the reaction of [Ru(η -C
5
Me
5 2 3 2 4 5 5
)(η -O ){P(OMe) } ] with HBF (R) affording [Ru(η -C Me ){P(O)
+
−1
(
OMe)
3
}{P(O)(OMe)
3
⋯HBF
4
}] (P). C-PCM/ωB97X calculations, dichloromethane as continuous medium. Relative Gibbs free energies in kcal mol .
Black path: Lowest-energy reaction pathway. Selected higher energy intermediates are depicted in red. Energy barrier for the oxygen transfer calcu-
lated at DFT C-PCM/EDF2 level. Pictures and Cartesian coordinates of the DFT-optimised geometries are collected in ESI.†
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
5
+
5
2
[
Ru(η -C
5
Me
5
){P(O)(OMe)
3
}{P(O)(OMe)
3
⋯HBF
4
}] (P) is coordi-
On this basis, we treated the complex [Ru(η -C
5
Me
5
2
)(η -O )
natively unsaturated and HBF interacts with one of the [OMe] {P(OEt) } ]BPh with a mixture of CH vCH and O (1 atm)
4
3 2
4
2
2
2
substituents. It is likely that the use of more coordinating and added triflic acid to test whether catalytic oxidation of
counter-anions, such as triflate or trifluoroacetate, affords ethylene may occur. Unfortunately, no catalytic cycle was
more stable products.
observed and the amount of detected acetic acid was the same
. This is probably due to
The acid-catalysed oxidation of coordinated phosphines in that was formed in the absence of O
2
2
5
2
1
our η -O
2
complex [Ru(η -C
5
Me
5
)(η -O
2 3 2 4
){P(OEt) } ]BPh (1) to the properties of the half-sandwich intermediate [Ru(κ -OTf)
1
5
+
give phosphate is rather slow and the formation of [Ru(κ -OTf) (η -C Me ){P(OEt) } ] [D] (Scheme 8), which exclusively gave
5
5
3 2
5
2
5
2
(
η -C
5
Me vCH
5
){P(O)(OEt)
3
}
2
] (7) was almost completed only after the η -CH
2
2
complex [Ru(η -C
5
Me
5
)(η -CH
2 2
vCH ){P
+
2
4 h. Such a slow intramolecular oxygen transfer prompted us (OEt) } ] (4a) in the reaction with ethylene and molecular
3 2
2
5
to test whether other substrates, e.g., alkenes, may be involved oxygen. The non-formation of the η -O derivative [Ru(η -
in oxygen transfer giving oxidised products. Because ethylene
did not react at room temperature with [Ru(η -C
2
2
+
C
5
Me
5
)(η -O
2 3 2
){P(OEt) } ] (1), which should be the key inter-
5
2
5
Me
5
)(η -O
2
){P mediate in the catalytic cycle, prevents the further oxidation
2
(
OEt) } ]BPh , we treated the η -O complex 1 in CDCl3 first reaction. In fact, after adding the acid, the NMR spectra of the
3
2
4
2
5
2
with CH
2
vCH
2
(1 atm) and then with two equivalents of triflic reaction mixture containing [Ru(η -C
5
Me
5
)(η -O
2 3 2
){P(OEt) } ]
acid. The progress of the reaction was monitored by NMR BPh
spectra, which showed that the addition of HOTf caused the complex [Ru(η -C Me )(η -CH vCH ){P(OEt) } ]BPh both in
4
and ethylene showed the formation of the ethylene
5
2
5
5
2
2
3 2
4
disappearance of the signals of starting complex 1 and the for- the absence and in the presence of free O
2
, which prevents the
mation of acetic acid CH COOH (Scheme 7), besides the activation by coordination of the dioxygen molecule in a cata-
3
1
5
known phosphate complex [Ru(κ -OTf)(η -C Me ){P(O)(OEt) } ] (7). lytic oxidation process.
5
5
3 2
2
In the spectra, the signal of the known η -CH
2
vCH
2
derivative
5
2
+
[
Ru(η -C
The formation of acetic acid is rather surprising and indicated
that intermolecular oxygen transfer can also occur, giving oxi- η -Alkene complexes [Ru(η -C
5
Me
5
)(η -CH
2
vCH
2
){P(OEt)
3
}
2
]
(4a) also appeared.
Characterisation of complexes
2
5
2
5
Me
5
)(η -CH
2
vCH
2
){P(OEt)
]BPh
tion. Indeed, inter- and intramolecular processes are in com- (5) and the vinylidene derivative [Ru(η -C Me ){vCvC(H)Ph}
3
}L]
5
2
dation products of the organic substrate present in the solu- BPh
4
(4), [Ru(η -C
5
Me
5
){η -CHvCHCO(O)CO}{P(OEt)
3
}
2
4
5
5
5
3 2 4
petition, where a prevalence of the intramolecular gives phos- {P(OEt) } ]BPh (6) were separated as yellow or orange solids,
phate. The ratio between complex 7 and acetic acid is about stable in air and in solution of polar organic solvents, where
1
1
6
: 1. The formation of acetic acid may tentatively be explained they behave as 1 : 1 electrolytes. Analytical and spectroscopic
as being based on the protonation of ethylene by HOTf. This data (IR and NMR) support the proposed formulation. Besides
+
gives the carbocation CH
2
CH
3
, which behaves as an electro- the signals of the ancillary ligands C
5
Me
5 3
and P(OEt) and of
2
1
phile on the coordinated η -O and gives a peroxo intermedi- the BPh4 anion, the H NMR spectrum of the ethylene
2
5
2
ate of the type [C] (Scheme 8). This intermediate may either complex
[Ru(η -C
5
Me
5
)(η -CH
2
vCH
2
){P(OEt)
3
}
2
]BPh
4
(4a)
give intramolecular oxygen transfer, affording phosphate shows one triplet at 3.05 ppm (JPH = 3.5 Hz) due ethylene
complex 7, or lose the ethylene peroxo species CH –CH –O–O, ligand protons. Instead, the spectrum of the related complex
2
2
5
2
which tautomerises giving acetic acid. In all cases and irre- [Ru(η -C
spective of the underlying mechanism, the formation of two multiplets, at 2.48 and 2.31 ppm, attributable to the η -
CH COOH indicates that our dioxygen complex 1 also behaves CH vCH ligand. Lowering the sample temperature caused
5
Me
5
2 2 3 3 4
)(η -CH vCH ){P(OEt) }(PPh )]BPh (4b) shows
2
3
2
2
towards ethylene as an oxidising agent.
some variations in the spectrum, but ethylene peaks are broad
even at −90 °C, indicating that the rotation of CH vCH still
2
2
took place at this temperature. However, the RT pattern of the
mixed-ligand compound 4b can be simulated by an ABCDXY
3
1
model (X, Y =
P) with the parameters listed in the
Experimental section and the good fit between the calculated
and experimental spectra strongly supports the proposed attri-
bution. Similar behaviour has been observed in strictly-com-
1
0c
parable complexes.
In the temperature range between +20
3
1
and −80 °C, the P NMR spectrum of the phosphite complex
4
4
a is a singlet at 131.5 ppm, whereas that of the mixed-ligand
b is an AX quartet, fitting the proposed formulation for the
complexes.
The IR and NMR spectra of maleic anhydride [Ru(η -C
5
5
Me
(5) and vinylidene
){vCvC(H)Ph}{P(OEt) ]BPh (6) are
5
)
2
{
η -CHvCHCO(O)CO}{P(OEt) } ]BPh
3
2
4
5
derivative [Ru(η -C
5
Me
5
3
}
2
4
1
0c
exactly the same of the sample previous reported by us and
Scheme 7
will not be discussed further.
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
Scheme 8 Proposed reaction path.
1
5
Phosphate complexes [Ru(κ -OTf)(η -C
5
Me
5
){P(O)(OEt)
3
}
2
]
(OMe)
3
}] (8) derivatives. Protonation of oxygen complexes
1
5
(
7) and [Ru(κ -OTf)(η -C
5
Me
5
){P(O)Ph
3
}{P(O)(OMe) }] (8) were under CH vCH (1 atm) gives, besides phosphate, acetic acid.
3 2 2
1
31
obtained as oils. However, the H and P NMR data support
the proposed formulation showing, in the proton spectra, the
5
signals of the η -C
5
Me
5
, of the phosphate P(O)(OEt)
3
and of
Experimental
the phosphine oxide P(O)Ph ligands. In particular, a quintet at
3
4
.27 and a triplet at 1.36 ppm appear in the proton spectra of Materials and physical measurements
, due to the OCH CH substituents of P(O)(OEt) , whereas the
P spectrum is a singlet at −2.77 ppm of the phosphate.
7
2
3
3
All synthetic work was carried out in an appropriate atmo-
sphere (Ar, N ) using standard Schlenk techniques or in an
3
1
2
1
Instead, in the H NMR, a doublet at 3.89 ppm of P(O)(OMe)
3
inert atmosphere dry-box. All solvents were dried over appro-
priate drying agents, degased on a vacuum line, and distilled
into vacuum-tight storage flasks. RuCl ·3H O was a Pressure
3
1
is observed for 8, whereas the P spectrum shows a singlet at
0.5 ppm, attributed to P(O)Ph and another at 0.47 ppm, due
3
3
3
2
to P(O)(OMe)
3
, fitting the proposed formulation.
Chemical Co. (USA) product, whereas pentamethyl-
cyclopentadiene C Me H was a STREM (USA) product, used as
Good analytical data were obtained for the tris(isocyanide)
5
5
5
t
derivative [Ru(η -C Me )( BuNC) ]BPh (9), which was isolated
t
5
5
3
4
3 3
received. Phosphites P(OMe) and P(OEt) and butylisocyanide
as an orange solid stable in air and in solution of polar
were Aldrich products used as received. Other reagents were
purchased from commercial sources in the highest available
purity and used as received. Infrared spectra were recorded on
a PerkinElmer Spectrum-One FT-IR spectrophotometer. NMR
1
1
organic solvents, where it behaves as a 1 : 1 electrolyte. Its IR
−
1
spectrum shows two strong bands at 2175 and 2230 cm
,
1
attributed to the νCN of the isocyanide ligands. The H NMR
spectrum supports the presence of the BuNC ligands, showing
a singlet at 1.48 ppm of the Bu protons, while a singlet at
t
1
13
31
spectra ( H, C, P) were obtained on an AVANCE 300 Bruker
t
spectrometer at temperatures between −90 and +25 °C, unless
5
1
.88 ppm is attributed to the methyl protons of the η -C
5
Me
5
,
1
13
otherwise noted. H and C spectra are referred to internal
in agreement with the proposed formulation.
31
1
tetramethylsilane. P{ H} chemical shifts are reported with
respect to 85% H PO , with downfield shifts considered posi-
tive. COSY, HMQC and HMBC NMR experiments were per-
3
4
1
7
formed with standard programs. The iNMR software package
Conclusions
−
3
was used to treat NMR data. The conductivity of 10 mol
−3
In this paper we report that dioxygen complexes 1–3, stabilised dm solutions of the complexes in CH
3
NO
2
at 25 °C was
5
+
by the half-sandwich fragment [Ru(η -C Me ){P(OR) }L] [L = measured on a Radiometer CDM 83. Elemental analyses were
5
5
3
P(OR)
3 3
, PPh ] undergo intramolecular oxygen transfer in the determined in the Microanalytical Laboratory of the
1
5
presence of acid, affording phosphate [Ru(κ -OTf)(η -C
5
Me
5
){P Dipartimento di Scienze del Farmaco, University of Padova
1
5
(O)(OEt) } ] (7) and [Ru(κ -OTf)(η -C Me ){P(O)Ph }{P(O) (Italy).
3
2
5
5
3
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
Synthesis of the complexes
JAD = JBC = 8.35, JAX = JBX = 5.50, JAY = JBY = 0.70, JCX = JDX =
5
5.50, JCY = JDY = 0.75 (4H, CH vCH ), 1.42 (br, 15H, CH Cp*),
2
2
3
Pentamethylcyclopentadienyl
complexes [RuCl(η -C
5 5
Me )
3
1
1
5
1.29 (t, 9H, CH
3
phos); P{ H} NMR (CD
2
Cl
2
, 20 °C) δ: AX spin
{
P(OEt)
3
}
2
] and [RuCl(η -C
5
Me
5
)(PPh ){P(OR) }] (R = Me, Et)
were prepared following the methods previously reported.
3
3
1
0b
syst., 116.2,
δ
A
δ
X
42.5, = 52.3; Anal. calcd for
J
AX
C H BO P Ru (1012.02): C, 71.21; H, 6.87; found: C, 71.04;
6
0
69
3
2
1
−1
2
5
2
5
2
H, 6.99%; Λ
M
= 51.6 Ω− mol cm .
[
Ru(η -C
5
Me
5
)(η -O
2
){P(OEt)
3
}
2
]BPh
4
(1) and [Ru(η -C
5
Me
5
)(η -
O )(PPh ){P(OR) }]BPh (2, 3) [R = Me (2), Et (3)]
5
2
5
2
3
3
4
[
Ru(η -C
5
Me
5
)(η -ma){P(OEt)
3
}
2
]BPh
4
(5) and [Ru(η -C
5
Me
5
)
In a 25 mL three-necked round-bottomed flask were placed {vCvC(H)Ph}{P(OEt) } ]BPh (6) [ma = CHvCHCO(O)CO]
3
2
4
0
.3 mmol of either the appropriate chloro compounds [RuCl
An excess (0.3 mmol) of the appropriate reagent
5
5
(
η -C
5
Me
5
){P(OEt)
3
}
2
5 5 3 3
] or [RuCl(η -C Me )(PPh ){P(OR) }], an
CHvCHCO(O)CO (ma) (29 mg) or PhCuCH (34 µL) was added
excess of NaBPh (0.6 mmol, 205 mg), 10 mL of ethanol and
8
to stir under air (1 atm) at room temperature for 48 h. The
solvent was removed under reduced pressure to give an oil,
which was triturated with ethanol (2 mL) until a yellow solid
5
2
4
to a solution of the dioxygen complex [Ru(η -C
5
Me
5
2
)(η -O )
mL of dichloromethane. The resulting solution was allowed
{
P(OEt) ]BPh (1) (100 mg, 0.109 mmol) in 10 mL of 1,2-
3
}
2
4
dichloroethane and the reaction mixture refluxed for 1 h. The
solvent was removed under reduced pressure to give an oil,
which was triturated with ethanol (1 mL). A yellow solid separ-
ated out, which was filtered and crystallised from CH Cl and
separated out, which was filtered and crystallised from CH
and EtOH; yield 85% (235 mg) for 1, 79% (231 mg) for 2, 81%
2 2
Cl
2
2
EtOH; yield 84% (90 mg) for 5, 81% (87 mg) for 6.
(
247 mg) for 3.
: IR (KBr, cm− ) νO–O 935 (m); H NMR (CD
.32–6.87 (m, 20H, Ph), 4.17 (m, 12H, CH ), 1.70 (t, 15H, CH
−1
1
5
: IR (KBr, cm ) νCO 1825, 1752 (s); H NMR (CD
2 2
Cl ,
1
1
1
2 2
Cl , 20 °C) δ:
2
2
0 °C) δ: 7.35–6.86 (m, 20H, Ph), 4.12 (m, 12H, CH ), 3.87 (t,
2
7
2
3
H, vCH), 1.58 (br, 15H, CH
3
Cp*), 1.37 (t, 18H, CH
, 20 °C) δ: A spin syst., 130.0 (s); Anal.
calcd for C H BO P Ru (985.89): C, 60.91; H, 6.85; found: C,
3
phos);
3
1
1
Cp*), 1.35 (t, 18H, CH phos); P{ H} NMR (CD Cl , 20 °C) δ: 31
A
C, 60.06; H, 7.12; found: C, 59.87; H, 7.19%; Λ = 52.6
Ω
1
3
2
2
P{ H} NMR (CD
2
Cl
2
2
2
spin syst., 117.0 (s); Anal. calcd for C46
H
65BO
8
P
2
Ru (919.83):
5
0
67
9 2
−1
−1
2
M
60.76; H, 6.94%; Λ
M
= 51.9 Ω mol cm .
−
1
−1
2
mol cm .
: IR (KBr, cm−1) νRuvCv 1646 (m); H NMR (CD
1
6
2
Cl
2
, 20 °C)
1
2
: H NMR (CD
2
Cl
2
, 20 °C) δ: 7.44–6.81 (m, 35H, Ph), 3.37
δ: 7.63–6.88 (m, 25H, Ph), 5.60 (t, 1H, vCH), 4.06 (m, 12H,
3
1
1
(d, 9H, CH3 phos), 1.38 (dd, 15H, CH3 Cp*); P{ H} NMR
31
1
CH
NMR (CD
(
(
1
2
), 1.88 (t, 15H, CH
Cl , 20 °C) δ: A
CD Cl , 20 °C): 360.85 (t, J = 18.5 Hz, RuvCv), 165–122
3
Cp*), 1.31 (t, 18H, CH
3
phos); P{ H}
(CD Cl , 20 °C) δ: AX spin syst., δ 119.15, δ 36.2, J = 90.41;
13
2
2
A
X
AX
2
2
2
spin syst., 136.9 (s); C NMR
Anal. calcd for C55
found: C, 67.62; H, 6.04%; ΛM = 53.2 Ω mol cm .
5 2
H59BO P Ru (973.88): C, 67.83; H, 6.11;
2
2
CP
−1
−1
2
m, Ph), 116.29 (s, vCH), 104.84 (d, C
6.13 (t, CH phos), 10.06 (s, CH
C H BO P Ru (989.97): C, 65.52; H, 7.23; found: C, 65.33; H,
5
Cp*), 63.50 (t, OCH
2
),
1
3
: H NMR (CD Cl , 20 °C) δ: 7.80–6.86 (m, 35H, Ph), 4.05
2 2
3
3
Cp*); Anal. calcd for
2 3 3
(qnt, 6H, CH ), 1.43 (dd, 15H, CH Cp*), 1.30 (t, 9H, CH
5
4
71
6 2
3
1
1
phos); P{ H} NMR (CD Cl , 20 °C) δ: AX spin syst., δ 113.9,
δX 36.62, JAX = 91.38; Anal. calcd for C H BO P Ru (1015.96):
C, 68.57; H, 6.45; found: C, 68.40; H, 6.57%; Λ
mol cm .
−1
−1
2
2
2
A
7.19%; Λ
M
= 52.5 Ω mol cm .
58
65
5 2
= 54.1 Ω−
1
Protonation of [Ru(η -C
5
Me
)(η -O
2
){P(OEt)
}
]BPh
(1) and
M
5
5
2
3
2
4
−
1
2
5
2
[Ru(η -C Me )(η -O )(PPh ){P(OMe) }]BPh (2)
5
5
2
3
3
4
5
A solution of the appropriate dioxygen complex [Ru(η -C
5
Me
5
)
5
2
[
(
Ru(η -C
5
Me
5
)(η -CH
2
vCH
2
){P(OEt)
3
}L]BPh
4
(4) [L = P(OEt)
3
2
5
2
(
η -O ){P(OEt) } ]BPh
(1) or [Ru(η -C Me )(η -O )(PPh )
2
3 2
4
5
5
2
3
a), PPh (b)]
3
{
P(OMe)
3
}]BPh
4
2 2
(2) (0.02 mmol) in CD Cl (1.0 mL), placed in
5
A solution of the appropriate dioxygen complex [Ru(η -C
5
Me
5
)
a 5 mm NMR tube, was cooled to −30 °C and then one equi-
2
(
η -O ){P(OEt) }L]BPh (1–3) (0.11 mmol) in 10 mL of 1,2- valent of HOTf (0.02 mmol, 1.8 µL) was added. The tube was
2
3
4
dichloroethane was refluxed under ethylene (1 atm) for 1 h. introduced into the NMR probe, pre-cooled to −30 °C,
The solvent was removed under reduced pressure to leave an and spectra recorded. Additional amounts of HOTf were added
oil, which was triturated with ethanol (1 mL). A yellow solid up to three equivalents and after each addition spectra
slowly separated out, which was filtered and crystallised from recorded.
CH
for 4b.
2 2
Cl and EtOH; yield 87% (88 mg) for 4a, 85% (95 mg)
1
5
1
5
[
Ru(κ -OTf)(η -C
5 5 3 2
Me ){P(O)(OEt) } ] (7) and [Ru(κ -OTf)(η -
1
C Me ){P(O)Ph }{P(O)(OMe) }] (8)
5
5
3
3
4
a: H NMR (CD
2
Cl
2
, 20 °C) δ: 7.45–6.87 (m, 20H, Ph), 4.08
vCH , JPH = 3.5 Hz), 1.62 An excess of triflic acid (0.33 mmol, 29 µL) was added to the
(
(
(
m, 12H, CH phos), 3.05 (t, 4H, CH
s, 15H, CH3 Cp*), 1.35 (t, 18H, CH3 phos); P{ H} NMR solution of the appropriate dioxygen complex [Ru(η -C Me )
CD
2
2
2
3
1
1
5
5
5
2
5
2
2
Cl
2
, 20 °C) δ: A
2
spin syst., 131.5 (s); Anal. calcd for (η -O
2
){P(OEt)
}]BPh
−80 °C. The reaction mixture was allowed to reach room tem-
3
}
2
]BPh
4
(1) or [Ru(η -C
5
Me
5
)(η -O
2
(10 mL) cooled to
2
)(PPh
3
)
C
7
48
H
69BO
6
P
2
Ru (915.89): C, 62.95; H, 7.59; found: C, 63.13; H, {P(OMe)
3
4
(2) (0.11 mmol) in CH
2
Cl
.44%; Λ = 52.3 Ω− mol cm .
1
−1
2
M
1
4
b: H NMR (CD
2
Cl
2
, 20 °C) δ: 7.55–6.87 (m, 35H, Ph), 4.02 perature and stirred for 24 h. The solvent was removed under
1
31
(m, 6H, CH
2
phos), ABCDXY spin syst. (ABCD = H; X, Y = P), reduced pressure, leaving an oil which we were not able to sep-
δA = δB 2.48, δC = δD 2.31, JAB = JCD = 13.2, JAC = JBD = −1.00, arate as a solid.
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
1
7
: H NMR (CD
2
Cl
2
, 20 °C) δ: 4.27 (qnt, 12H, CH
2
), 1.94 (br, lents of HOTf (0.2 mmol, 17.6 µL). The reaction mixture was
3
1
1
1
31
1
2
5H, CH Cp*), 1.36 (t, 18H, CH phos); P{ H} NMR (CD Cl , left to reach room temperature and H and P NMR spectra
3
3
2
2
= 4.2 Ω− mol cm .
1
−1
2
1
0 °C) δ: A
2
spin syst., −2.77 (s); Λ
M
3 3
recorded. H NMR (CDCl , 20 °C) δ: 2.07 (s, 3H, CH HAc).
1
8
: H NMR (CD
2
Cl
2
, 20 °C) δ: 7.69–7.44 (m, 15H, Ph phos),
3
1
1
3
.89 (d, 9H, CH phos), 1.91 (s, 15H, CH Cp*); P{ H} NMR Crystal structure determinations
3
3
(
CD
2 2 3
Cl , 20 °C) δ: A + A spin syst., 30.5 [s, P(O)Ph ], 0.47 [s,
Crystallographic data were collected in the CACTI
Universidade de Vigo) at low temperature using a Bruker D8
−
1
−1
2
P(O)(OMe)
3
M
]; Λ = 3.9 Ω mol cm .
(
5
t
Venture with a CMOS Photon 100 detector and Mo-Kα radi-
ation (λ = 0.71073 Å) equipped with a CryoStream 800 system.
Preparation of [Ru(η -C Me )( BuNC) ]BPh (9) and separation
of P(O)(OEt)3
5
5
3
4
1
8
The software APEX3 was used for collecting frames of data,
indexing reflections, and the determination of lattice para-
An excess of HOTf (0.6 mmol, 53 µL) was added to a solution
of the dioxygen complex [Ru(η -C
1) (184 mg, 0.2 mmol) in 7 mL of dichloromethane, cooled to
80 °C. The reaction mixture was allowed to reach room tem-
5
2
5
Me
5
)(η -O
2
){P(OEt)
3
}
2
]BPh
4
18
meters, SAINT for integration of intensity of reflections, and
(
−
18
SADABS for scaling and empirical absorption correction. The
crystallographic treatment was performed with the Oscail
perature, stirred for 24 h, and then an excess of
19
program The structures of all the compounds were solved by
t
butylisocyanide (CH
h of stirring, the solvent was removed under reduced
pressure to give an oil, which was triturated with ethanol
3 mL) containing an excess of NaBPh (0.4 mmol, 137 mg). A
yellow solid separated out, which was filtered and crystallised
from CH Cl and EtOH; yield 83% (134 mg).
3
)
3
CNC (1.0 mmol, 113 µL) added. After
20
using the SHELXT program and refined by a full-matrix least-
2
2
21
squares based on F , SHELXL program. Non-hydrogen atoms
were refined with anisotropic displacement parameters.
Hydrogen atoms were included in idealised positions and
refined with isotropic displacement parameters. For com-
(
4
2
2
22
pound 3, the Squeeze program was used to eliminate the
The mother liquor was chromatographed on a silica gel
column (60 cm) using petroleum ether 40–60 °C as eluent. The
first eluted species was evaporated to dryness and character-
ised by H and P NMR spectra as P(O)(OEt)
It is worth noting that free P(OEt) was not oxidised by air
to P(O)(OEt) under the same conditions used for the for-
3
reflections due a disorder solvent. In addition, some disorder
was found in one of the ethoxy groups in this compound.
Details of crystal data and structural refinement are given in
Table 2. CCDC 1842088–1842090† contain the supplementary
crystallographic data for this paper.
1
31
3
(yield ≥ 75%).
3
mation of 7.
Computational details
: IR (KBr, cm− ) νCN 2175 (m), 2130 (s); H NMR (CD Cl ,
1
1
9
2 2
The geometry optimisations and energy calculations were
2
1
0 °C) δ: 7.31–6.87 (m, 20H, Ph), 1.88 (s, 15H, CH
3
Cp*),
2
3
t
carried out using the hybrid-GGA EDF2 functional in combi-
nation with the 6-31G** basis set (ECP-based LANL2DZ basis
.48 (s, 27H, CH
3
Bu); Anal. calcd for C49
H
62BN
3
Ru (804.92):
C, 73.12; H, 7.76; found: C, 72.95; H, 7.62%; Λ = 54.8
Ω
M
2
4
25
−
1
−1
2
set for Ru) and the range-separated DFT functional ωB97X
mol cm .
1
in combination with the split-valence polarised basis set of
P(O)(OEt)
3 2 2 2
: H NMR (CD Cl , 20 °C) δ: 4.04 (m, 6H, CH ),
.28 (t, 9H, CH3); P{ H} NMR (CD Cl , 20 °C) δ: 0.81 ppm.
3
1
1
Ahlrichs and Weigend, with Dolg’s and co-workers ECP for the
1
2
2
2
6
ruthenium centre. The stationary points were characterised
by vibrational analysis, from which zero-point vibrational ener-
Separation of P(O)(OMe) and P(O)Ph
3
3
2
7
5
gies and thermal corrections (T = 298.15 K) were obtained.
The method was exactly like that used for precursor [Ru(η -
C
ligand derivative [Ru(η -C
After separation of the tris(isocyanide) complex 9, the mother
liquor was chromatographed on a silica gel column (60 cm)
using a mixture of petroleum ether 40–60 °C, dichloromethane
and ethanol in 20 : 5 : 2 ratio as eluent. The first eluted species
was evaporated to dryness and characterised as a mixture
2
The implicit solvation model C-PCM (ε = 9.08) was used for
5
Me
5
)(η -O
2 3 2 4
){P(OEt) } ]BPh (1), but starting from the mixed-
2
8
5
2
ωB97X optimisations and EDF2 single point calculations.
The Gaussian 09 Program was used for ωB97X calculations,
5
Me
5
2 3 3 4
)(η -O )(PPh ){P(OMe) }]BPh (2).
2
9
3
0
the Spartan’16 Program for EDF2 calculations. The software
Multiwfn (version 3.3.8) was used for Hirshfeld population
3
1
3
2
analyses.
(
3 3
ratio about 1 : 1) of P(O)Ph and P(O)(OMe) (yield ≥ 70%).
1
P(O)(OMe) : H NMR (CDCl , 20 °C) δ: 3.76 (d, 9H, CH );
3
3
3
Conflicts of interest
3
1
1
P{ H} NMR (CDCl
3
, 20 °C) δ: 2.6 ppm.
1
P(O)Ph
3
: H NMR (CDCl
3
, 20 °C) δ: 7.78, 7.45 (m, 15H, Ph); There are no conflicts of interest to declare.
3
1
1
P{ H} NMR (CDCl , 20 °C) δ: 29.6 ppm.
3
5
2
Protonation of [Ru(η -C Me )(η -O ){P(OEt) } ]BPh (1) under
5
5
2
3 2
4
Acknowledgements
CH
A solution of the dioxygen complex 1 (92 mg, 0.1 mmol) in The financial support of MIUR (Italy) – PRIN 2016 is gratefully
mL of CDCl was allowed to stand under a CH vCH atmo- acknowledged. We thank Daniela Baldan, from the Università
2 2
vCH atmosphere
5
3
2
2
sphere (1 atm), cooled to −30 °C and treated with two equiva- Ca’ Foscari Venezia (Italy), for technical assistance.
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
Table 2 Crystal data and structure refinement
Identification code
1
2
3
Empirical formula
Moiety formula
Formula weight
Temperature (K)
Wavelength (Å)
C
C
46
H
65BO
8
P
2
Ru
C
C
56
H
61BCl
2
O
5
P
2
Ru
C
C
58
H
65BO
5
P
2
Ru
H
22 45
O
8
P
2
Ru, C24
20
H B
H
31 39
O
5
P
2
Ru, C24
H20B, CH
Cl
2 2
H
34 45
5
O P
2
Ru, C24H B
20
919.80
100(2)
0.71073
1058.76
100(2)
0.71073
1015.92
100(2)
0.71073
Crystal system
Space group
Triclinic
Pˉ1
Triclinic
Pˉ1
Triclinic
Pˉ1
Unit cell dimensions (a, b, c (Å))
a = 10.1044(7)
b = 13.9566(11)
c = 17.0124(13)
α = 85.731(2)
β = 77.016(2)
γ = 83.628(2)
2320.3(3)
2
a = 12.8026(13)
b = 13.4361(12)
c = 16.0287(17)
α = 85.349(5)
β = 84.245(5)
γ = 69.965(4)
2574.1(4) Å
2
1.366
0.518
1100
a = 10.7189(9)
b = 14.4422(13)
c = 17.6629(16)
α = 98.425(3)
β = 102.113(3)
γ = 90.545(3)
2642.3(4) Å
2
1.277
0.404
1064
(α, β, γ (°))
3
3
3
Volume (Å )
Z
−1
Calc. ρ (Mg m
)
1.317
0.457
968
−
1
μ (mm
F(000)
)
Crystal size (mm)
Θ range (°)
Index ranges
0.174 × 0.102 × 0.095
2.460 to 28.372
−13 ≤ h ≤ 13
0.085 × 0.053 × 0.048
2.204 to 28.426
−17 ≤ h ≤ 17
−17 ≤ k ≤ 17
−21 ≤ l ≤ 21
86 507
0.211 × 0.142 × 0.063
2.364 to 28.458.
−14 ≤ h ≤ 14
−19 ≤ k ≤ 19
−23 ≤ l ≤ 23
163 708
−
18 ≤ k ≤ 18
22 ≤ l ≤ 22
−
Reflections collected
100 099
Independent reflections
Reflections observed (>2σ)
Data completeness
Absorption correction
Max. and min. transmission
Refinement method
11 590 [R(int) = 0.0267]
10 796
0.997
Semi-empirical from equivalents
0.7457 and 0.7242
Full-matrix least-squares on F
12 844 [R(int) = 0.0599]
11 026
0.993
13 230 [Rint = 0.0329]
12 407
0.991
0.7394 and 0.6994
0.7444 and 0.7206
2
Data/restraints/parameters
Goodness-of-fit on F
11 590/0/535
1.064
12 844/0/614
1.038
13 229/0/632
1.049
2
Final R indices [I > 2σ(I)]
R indices (all data)
R
1
= 0.0229
wR = 0.0586
= 0.0259
wR = 0.0600
0.373 and −0.556
R
1
= 0.0417
wR = 0.0922
= 0.0532
wR = 0.0970
2.034 and −2.269
R
1
= 0.0244
wR = 0.0618
= 0.0280
wR = 0.0635
0.476 and −0.505
2
2
2
R
1
R
1
R
1
2
2
2
Largest diff. peak and hole (e Å−
3
)
(
e) B. R. James, Dioxygen Activation and Homogeneous
References
Catalytic Oxidation, ed. L. I. Simàndi, Elsevier, Amsterdam,
NL, 1991, p. 195; (f) H. Mimoun, Angew. Chem., Int. Ed.
Engl., 1982, 21, 734–750; (g) H. Mimoun, Pure Appl. Chem.,
1981, 53, 2389–2399; (h) R. A. F. Tomas, J. C. M. Bordado
and J. F. P. Gomes, Chem. Rev., 2013, 113, 7421–7469;
(i) L. Boisvert and K. I. Goldberg, Acc. Chem. Res., 2012, 45,
899–910; ( j) Z. Shi, C. Zhang, C. Tang and N. Jiao, Chem.
Soc. Rev., 2012, 41, 3381–3430.
3 (a) W. A. Nugent and J. M. Mayer, Metal-Ligand Multiple
Bonds, Wiley, New York, USA, 1988; (b) D. W. Pipes and
T. J. Meyer, Inorg. Chem., 1986, 25, 4042–4050;
(c) C. M. Che, T. F. Lai and K. Y. Wong, Inorg. Chem., 1987,
26, 2289–2299; (d) M. E. Marmion and K. J. Takeuchi,
J. Am. Chem. Soc., 1988, 110, 1472–1480; (e) C. M. Che,
W. K. Cheng and V. W. W. Yam, J. Chem. Soc., Dalton
Trans., 1990, 3095–3100; (f) M. Bourgault, A. Castillo,
M. A. Esteruelas, E. Oñate and N. Ruiz, Organometallics,
1997, 16, 636–645; (g) H. Molina-Svendsen, G. Bojesen and
C. J. McKenzie, Inorg. Chem., 1998, 37, 1981–1983;
(h) M. J. Camenzind, B. R. James and D. Dolphin, J. Chem.
Soc., Chem. Commun., 1986, 1137–1139; (i) D. K. Dogutan,
1
(a) Active Oxygen in Biochemistry, ed. J. S. Valentine,
C. S. Foote, A. Greenberg and J. F. Liebman, Blackie
Academic and Professional, London, UK, 1995; (b) L. Que
and R. Y. N. Ho, Chem. Rev., 1996, 96, 2607–2624;
(
c) B. J. Wallar and J. D. Lipscomb, Chem. Rev., 1996, 96,
625–2658; (d) M. Sono, M. P. Roach, E. D. Coulter and
J. H. Dawson, Chem. Rev., 1996, 96, 2841–2888;
e) V. R. I. Kaila, M. I. Verkhovsky and M. Wikström, Chem.
2
(
Rev., 2010, 110, 7062–7081; (f) E. I. Solomon, P. Chen,
M. Metz, S.-K. Lee and A. E. Palmer, Angew. Chem., 2001,
1
13, 4702–4724, (Angew. Chem., Int. Ed., 2001, 40, 4570–
4
590); (g) I. G. Denisov, T. M. Makris, S. G. Sligar and
I. Schlichting, Chem. Rev., 2005, 105, 2253–2278.
2
(a) A. S. Matlack, Introduction to Green Chemistry, Marcel
Dekker, New York, USA, 2001; (b) S. S. Stahl, Angew. Chem.,
2
3
004, 116, 3480–3501, (Angew. Chem., Int. Ed., 2004, 43,
400–3420); (c) S. S. Stahl, Science, 2005, 309, 1824–1826;
(
d) The Activation of Dioxygen and Homogeneous Catalytic
Oxidation, ed. D. H. R. Barton, A. E. Martell and
D. T. Sawyer, Plenum, London, New York, USA, 1993;
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018

View Article Online
Dalton Transactions
Paper
S. A. Stoian, R. McGuire, M. Schwalbe, T. S. Teets and
D. G. Nocera, J. Am. Chem. Soc., 2011, 133, 131–140;
Chem., Int. Ed., 2013, 52, 3634–3637; (f) D. Munz and
T. Strassner, Inorg. Chem., 2015, 54, 5043–5052;
(g) T. Ishizuka, S. Ohzu and T. Kojima, Synlett, 2014, 1667–
1679; (h) K. Gogoi, S. Saha, B. Mondal, H. Deka, S. Ghosh
and B. Mondal, Inorg. Chem., 2017, 56, 14438–14445;
(i) T. Bolaño, M. A. Esteruelas, M. P. Gay, E. Oñate,
I. M. Pastor and M. Yus, Organometallics, 2015, 34,
3902–3908.
(
j) J. Y. Yang, R. M. Bullock, W. G. Dougherty, W. S. Kassel,
B. Twamley, D. L. DuBois and M. Rakowski DuBois, Dalton
Trans., 2010, 39, 3001–3010; (k) R. L. Shook, S. M. Peterson,
J. Greaves, C. Moore, A. L. Rheingold and A. S. Borovik,
J. Am. Chem. Soc., 2011, 133, 5810–5817.
4
(a) A. Sen and J. Halpern, J. Am. Chem. Soc., 1977, 99, 8337–
8
339; (b) A. van Asselt, M. S. Trimmer, L. M. Henling and
J. E. Bercaw, J. Am. Chem. Soc., 1988, 110, 8254–8255;
c) S. Bhaduri, L. Casella, R. Ugo, P. R. Raithby, C. Zuccaro
and M. B. Hursthouse, J. Chem. Soc., Dalton Trans., 1979,
624–1628; (d) K. Kirchner, K. Mauthner, K. Mereiter and
R. Schmid, J. Chem. Soc., Chem. Commun., 1993, 892–894;
e) K. Mauthner, K. Mereiter, R. Schmid and K. Kirchner,
6 (a) J. C. Dobson, W. K. Seok and T. J. Meyer, Inorg. Chem.,
1986, 25, 1513–1514; (b) C. M. Che, C. K. Li, W. T. Tang and
W. Y. Yu, J. Chem. Soc., Dalton Trans., 1992, 3153–3158;
(c) A. S. Goldstein, R. H. Beer and R. S. Drago, J. Am. Chem.
Soc., 1994, 116, 2424–2429; (d) L. K. Stultz, R. A. Binstead,
M. S. Reynolds and T. J. Meyer, J. Am. Chem. Soc., 1995,
117, 2520–2532; (e) T. S. Lai, H. L. Kwong, R. Zhang and
C. M. Che, J. Chem. Soc., Dalton Trans., 1998, 3559–3564.
7 (a) J. T. Groves and T. E. Nemo, J. Am. Chem. Soc., 1983,
105, 6243–6248; (b) A. S. Goldstein and R. S. Drago,
J. Chem. Soc., Chem. Commun., 1991, 21–22; (c) A. J. Bailey,
W. P. Griffith and P. D. Savage, J. Chem. Soc., Dalton Trans.,
1995, 3537–3542.
8 (a) G. Albertin, S. Antoniutti, F. Callegaro and J. Castro,
Organometallics, 2009, 28, 4475–4479; (b) G. Albertin,
S. Antoniutti, J. Castro and S. Paganelli, J. Organomet.
Chem., 2010, 695, 2142–2152; (c) G. Albertin, S. Antoniutti,
J. Castro and S. García-Fontán, Eur. J. Inorg. Chem., 2011,
510–520; (d) G. Albertin, S. Antoniutti, J. Castro and S. Da
Lio, Organometallics, 2013, 32, 3651–3661; (e) G. Albertin,
S. Antoniutti, J. Castro and F. Scapinello, J. Organomet.
Chem., 2014, 751, 412–419; (f) G. Albertin, S. Antoniutti,
M. Bortoluzzi, A. Botter and J. Castro, Dalton Trans., 2015,
44, 3439–3446; (g) G. Albertin, S. Antoniutti, M. Bortoluzzi,
A. Botter and J. Castro, Dalton Trans., 2015, 44, 7411–7418.
9 (a) G. Albertin, S. Antoniutti, D. Baldan, J. Castro and
G. Comparin, Organometallics, 2013, 32, 3157–3160;
(b) G. Albertin, S. Antoniutti, A. Botter, J. Castro and
M. Giacomello, Organometallics, 2014, 33, 3570–3582;
(c) G. Albertin, S. Antoniutti, J. Castro and G. Dottorello,
Dalton Trans., 2015, 44, 9289–9303; (d) G. Albertin,
S. Antoniutti, M. Bortoluzzi, J. Castro and L. Marzaro,
Dalton Trans., 2015, 44, 15470–15480; (e) G. Albertin,
S. Antoniutti, M. Bortoluzzi, A. Botter, J. Castro and
F. Sibilla, RSC Adv., 2016, 6, 97650–97658.
(
1
(
Inorg. Chim. Acta, 1995, 236, 95–100; (f) M. Sato and
M. Asai, J. Organomet. Chem., 1996, 508, 121–127;
(
g) E. Lindner, M. Haustein, R. Fawzi, M. Steimann and
P. Wagner, Organometallics, 1994, 13, 5021–5029;
h) S. M. Maddock, C. E. F. Rickard, W. R. Roper and
L. James Wright, J. Organomet. Chem., 1996, 510, 267–279;
i) I. de los Ríos, M. Jiménez Tenorio, J. Padilla,
M. C. Puerta and P. Valerga, Organometallics, 1996, 15,
565–4574; ( j) T. Y. Bartucz, a. Golombek, A. J. Lough,
(
(
4
P. A. Maltby, R. H. Morris, R. Ramachandran and
M. Schlaf, Inorg. Chem., 1998, 37, 1555–1562;
(
k) P. Barthazy, M. Wörle and A. Mezzetti, J. Am. Chem. Soc.,
999, 121, 480–481; (l) G. Jia, W. S. Ng, H. S. Chu,
W.-T. Wong, N.-T. Yu and I. D. Williams, Organometallics,
999, 18, 3597–3602; (m) H. Yu, Y. Fu, Q. Guo and Z. Lin,
1
1
Organometallics, 2009, 28, 4443–4451; (n) P. Barthazy,
M. Wörle, H. Rüegger and A. Mezzetti, Inorg. Chem., 2000,
3
9, 4903–4912; (o) M. E. Navarro Clemente, P. J. Saavedra,
M. Cervantes Vásquez, M. A. Paz-Sandoval, A. M. Arif and
R. D. Ernst, Organometallics, 2002, 21, 592–605;
(
p) K. Fujita, R. Schenker, W. Gu, T. C. Brunold,
S. P. Cramer and C. G. Riordan, Inorg. Chem., 2004, 43,
324–3326; (q) J. Matthes, S. Gründemann, A. Toner,
3
Y. Guari, B. Donnadieu, J. Spandl, S. Sabo-Etienne, E. Clot,
H.-H. Limbach and B. Chaudret, Organometallics, 2004, 23,
1
424–1433; (r) L. Cuesta, E. Tomat, V. M. Lynch and
J. L. Sessler, Chem. Commun., 2008, 3744–3746;
s) W. M. Khairul, M. A. Fox, N. N. Zaitseva, M. Gaudio,
D. S. Yufit, B. W. Skelton, A. H. White, J. A. K. Howard, 10 (a) G. Albertin, S. Antoniutti, A. Botter and J. Castro, Inorg.
(
M. I. Bruce and P. J. Low, Dalton Trans., 2009, 610–620;
t) T. A. Tronic, M. R. DuBois, W. Kaminsky, M. K. Coggins,
T. Liu and J. M. Mayer, Angew. Chem., Int. Ed., 2011, 50,
0936–10939.
(a) S. L. Kuan, W. K. Leong, R. D. Webster and L. Y. Goh,
Chem., 2015, 54, 2091–2093; (b) G. Albertin, S. Antoniutti,
M. Bortoluzzi, A. Botter and J. Castro, Inorg. Chem., 2016,
55, 5592–5602; (c) G. Albertin, S. Antoniutti, M. Bortoluzzi,
A. Botter and J. Castro, J. Organomet. Chem., 2016, 822,
259–268.
(
1
5
Organometallics, 2012, 31, 5159–5168; (b) A. Yoshinari, 11 W. J. Geary, Coord. Chem. Rev., 1971, 7, 81–122.
A. Tazawa, S. Kuwata and T. Ikariya, Chem. – Asian J., 2012, 12 (a) L. J. Farrugia, J. Appl. Crystallogr., 1997, 30, 565;
7
, 1417–1425; (c) J. Cho, R. Sarangi and W. Nam, Acc. Chem.
(b) POV-Ray, v. 3.7 for Windows, Persistence of Vision Pty.
Res., 2012, 45, 1321–1330; (d) T. A. Tronic, W. Kaminsky,
Ltd., 2016 Persistence of Vision Raytracer (Version 3.7).
M. K. Coggins and J. M. Mayer, Inorg. Chem., 2012, 51, 13 A. Y. Kostukovich, D. I. D’yachihin, F. M. Dolgushin,
1
0916–10928; (e) F. Avenier, C. Herrero, W. Leibl,
A. F. Smolyakov, I. A. Godovikov and I. T. Chizhevsky,
A. Desbois, R. Guillot, J.-P. Mahy and A. Aukauloo, Angew.
Molecules, 2014, 19, 7094–7103.
This journal is © The Royal Society of Chemistry 2018
Dalton Trans.

View Article Online
Paper
Dalton Transactions
1
1
1
4 M. D. Palacios, M. C. Puerta, P. Valerga, A. Lledós and
E. Veilly, Inorg. Chem., 2007, 46, 6958–6967.
5 I. de los Ríos, M. Jiménez Tenorio, J. Padilla, M. C. Puerta
and P. Valerga, J. Chem. Soc., Dalton Trans., 1996, 377–381.
6 (a) H. Mimoun, M. M. Perez-Machirant and J. Seree de
Computing, NIC Series, Jülich, 2000, vol. 1, p. 479;
(b) P. J. Hay and W. R. Wadt, J. Chem. Phys., 1985, 82, 270–
283; (c) P. J. Hay and W. R. Wadt, J. Chem. Phys., 1985, 82,
299–310; (d) W. J. Henre, R. Ditchfield and J. A. Pople,
J. Chem. Phys., 1972, 56, 2257–2261.
Roch, J. Am. Chem. Soc., 1978, 100, 5437–5444; (b) V. Conte, 25 (a) Y. Minenkov, Å. Singstad, G. Occhipinti and
F. Di Furia and S. Moro, J. Mol. Catal. A: Chem., 1997, 120,
3–99; (c) M. Aresta, I. Tommasi, E. Quaranta, C. Fragale,
J. Mascetti, m. Tranquille, F. Galan and M. Fouassier,
V. R. Jensen, Dalton Trans., 2012, 41, 5526–5541;
(b) J.-D. Chai and M. Head-Gordon, Phys. Chem. Chem.
Phys., 2008, 10, 6615–6620; (c) I. C. Gerber and
J. G. Ángyán, Chem. Phys. Lett., 2005, 415, 100–105.
9
Inorg. Chem., 1996, 35, 4254–4260; (d) H. Suzuki,
S. Matsuura, Y. Moro-Oka and I. Ikawa, J. Organomet. 26 (a) F. Weigend and R. Ahlrichs, Phys. Chem. Chem. Phys.,
Chem., 1985, 286, 247–258.
7 G. Balacco, http: //www.inmr.net/.
2005, 7, 3297–3305; (b) D. Andrae, U. Haussermann,
M. Dolg, H. Stoll and H. Preuss, Theor. Chim. Acta, 1990,
77, 123–141.
1
1
8 Bruker, APEX3, SMART, SAINT, Bruker AXS Inc., Madison,
Wisconsin, USA, 2015.
9 P. McArdle, K. Gilligan, D. Cunningham, R. Dark and
M. Mahon, CrystEngComm, 2004, 6, 303–309.
0 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Adv., 2015,
27 C. J. Cramer, Essentials of Computational Chemistry, Wiley,
Chichester, 2nd edn, 2004.
28 (a) M. Cossi, N. Rega, G. Scalmani and V. Barone,
J. Comput. Chem., 2003, 24, 669–681; (b) V. Barone and
M. Cossi, J. Phys. Chem. A, 1998, 102, 1995–2001.
1
2
2
2
2
2
7
1, 3–8.
1 G. M. Sheldrick, Acta Crystallogr., Sect. C: Struct. Chem., 29 M. J. Frisch, et al., Gaussian 09, Revision C.01, Gaussian
015, 71, 3–8. Inc., Wallingford CT, USA, 2010.
2 A. L. Spek, Acta Crystallogr., Sect. C: Struct. Chem., 2015, 71, 30 (a) Spartan ‘16, Build 1.1.0, Wavefunction Inc., Irvine CA,
2
9
–18.
3 C. Y. Lin, M. W. George and P. M. W. Gill, Aust. J. Chem.,
004, 57, 365–370.
4 (a) M. Dolg, Modern methods and algorithms of quantum
USA, 2016; (b) Y. Shao, et al., Mol. Phys., 2015, 113,
184–215.
2
31 T. Lu and F. Chen, J. Comput. Chem., 2012, 33,
580–592.
chemistry, ed. J. Grotendorst, John Neumann Institute for 32 F. L. Hirshfeld, Theor. Chim. Acta, 1977, 44, 129–138.
Dalton Trans.
This journal is © The Royal Society of Chemistry 2018