Modified cyclopentadienyl molybdenum compounds with enhanced cytotoxic activity towards MOLT-4 leukaemia cells

Article abstract of DOI:10.1002/aoc.3759

A series of new cyclopentadienyl molybdenum compounds bearing substituted phenanthroline ligands [(η⁵-C₅H₄CH₂C₆H₄X-4)Mo(CO)₂(^N,NL)][BF₄] (X?=?F, Cl, Br;

Full text of DOI:10.1002/aoc.3759

Received: 4 November 2016
DOI 10.1002/aoc.3759
Revised: 2 January 2017
Accepted: 17 January 2017
F U L L PA P E R
Modified cyclopentadienyl molybdenum compounds with
enhanced cytotoxic activity towards MOLT‐4 leukaemia cells
Iva Honzíčková1 | Jaromír Vinklárek1 | Zdeňka Růžičková1 | Martina Řezáčová2 |
Jan Honzíček3
1 Department of General and Inorganic
Chemistry, Faculty of Chemical Technology,
University of Pardubice, Studentská 573, 532
10 Pardubice, Czech Republic
2 Department of Medical Biochemistry,
Faculty of Medicine in Hradec Králové,
Charles University in Prague, Šimkova 870,
500 01 Hradec Králové, Czech Republic
3 Institute of Chemistry and Technology of
Macromolecular Materials, Faculty of
Chemical Technology, University of
Pardubice, Studentská 573, 532 10
Pardubice, Czech Republic
A series of new cyclopentadienyl molybdenum compounds bearing substituted
phenanthroline ligands [(η5‐C5H4CH2C6H4X‐4)Mo(CO)2(N,NL)][BF4] (X = F, Cl,
Br; N,NL = phen, 5‐NH2‐phen, 4,7‐Ph2‐phen) was prepared and characterized using
infrared and NMR spectroscopies. Crystal structures of [(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(NCMe)2][BF4], [(η5‐C5H4CH2C6H4X‐4)Mo(CO)2(phen)][BF4] (X = F,
Cl, Br) and [(η5‐C5H4CH2C6H4Cl‐4)Mo(CO)2(4,7‐Ph2‐phen)][BF4]⋅(4,7‐Ph2‐
phen)⋅HBF4 were determined using X‐ray diffraction analysis. Biological studies
revealed a strong cytotoxic effect of the chelating ligands. Although the cytostatic
effect of the halogen in the side chain of the cyclopentadienyl ring is negligible, it
could be used for future post‐modification of these types of cytotoxic active molyb-
denum‐based compounds.
Correspondence
Jan Honzíček, Institute of Chemistry and
Technology of Macromolecular Materials,
Faculty of Chemical Technology, University
of Pardubice, Studentská 573, 532 10
Pardubice, Czech Republic.
KEYWORDS
cyclopentadienyl, cytotoxicity, fulvene, leukaemia therapy, molybdenum, X‐ray diffraction analysis
Email: jan.honzicek@upce.cz
1 | INTRODUCTION
ligands) were established as a new class of cytotoxic active
compounds against several tumour cell lines.[3] The most
Despite our constantly deepening knowledge about
pathobiochemical mechanisms of various haematological
malignancies, many leukaemias remain incurable and have
very poor survival prognoses. Although targeted therapy,
such as tyrosin kinase inhibitors or specific monoclonal anti-
bodies, has been a great revolution for the therapy of some
types of leukaemias, others rely fully on classical chemother-
apy.[1] For example, the core of the treatment regimen of
acute myeloid leukaemia has remained nearly unchanged
for 40 years, and the prognosis remains poor, mainly in
elderly patients. Therefore, research continues on novel cyto-
statics that would provide fewer undesirable side effects
while maintaining potent anti‐tumour activity.[2]
potent cytotoxic effect was observed for indenyl com-
plexes bearing 1,4‐bis(4‐tolyl)‐1,4‐diazabuta‐1,3‐diene, 4,7‐
diphenyl‐1,10‐phenanthroline, 1,2‐bis(diphenylphosphino)
ethane and 1,4,7‐trithiacyclononane. Their half maximal
inhibitory concentration (IC50) towards Ehrlich‐ascites cell
line ranges from 6 to 10 μmol l−1 [3]
Subsequent studies have
.
extended the series of cytotoxic active compounds and
brought an early insight into the mechanism of their
action.[4–12]
The aim of the work presented here was to enhance the
cytotoxicity of cyclopentadienyl molybdenum compounds
through modification of the active species. Two approaches
were chosen to achieve this goal. These were the attach-
ment of new halogenobenzyl substituents on the
cyclopentadienyl ring and coordination of substituted
phenanthroline ligands.
In 2005, the molybdenum(II) compounds [(η3‐C3H5)
Mo(CO)2L2Br], [(η5‐C5H5)Mo(CO)2L2][BF4] and [(η5‐
C9H7)Mo(CO)2L2][BF4] (L2 = N,N‐, S,S‐ and P,P‐chelating
Appl Organometal Chem. 2017;e3759.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.3759

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HONZÍČKOVÁ ET AL.
The substitution effects were evaluated for human
Mo(CO)2(NCMe)2Cl] (4) according to the protocol devel-
oped for the unsubstituted analogue.[15] The halogenobenzyl
substituents were attached to the cyclopentadienyl framework
MOLT‐4 leukaemia cells. This cell line is derived from
human T‐lymphoblastic leukaemia and shows specific sur-
face signs: CD1+ (49%), CD4+ (55%), CD5+ (72%) and
CD7+ (77%). MOLT‐4 contains wild type of protein p53,
which is crucial in the cell response to cytostatic therapy
and radiotherapy of p53wt tumours. The intact p53 pathway
predicts the cell line to be an excellent model for study of
molecular mechanism responding mainly to DNA
damage.[13,14]
using
a
well‐established fulvene protocol.[16,17] The
substituted benzaldehydes react with cyclopentadiene under
basic conditions to give fulvenes 1–3 (Scheme 1). These
intermediates were isolated and treated with SuperHydride
to give reactive cyclopentadienides 1‐Li–3‐Li.
The allyl molybdenum compounds 5–7 were character-
ized using infrared and NMR spectroscopies. The infrared
spectra show two CO stretching bands in the range typical
of terminal carbonyl ligands bound to molybdenum(II)
(Table 1). 1H NMR spectra show a broadened signal at
5.13 ppm (4H) that is assigned to protons of the
monosubstituted cyclopentadienyl ligand. The allyl ligands
give two doublets at ca 2.71 and ca 0.94 ppm and one multi-
plet at ca 3.91 ppm that is typical for the η3‐coordination
mode. The protons of the methylene bridge between the
cyclopentadienyl and benzene ring appear as one singlet at
ca 3.55 ppm. The 1,4‐disubstituted benzene ring gives two
doublets in the range 7.0–7.4 ppm with interaction constant
3J(1H,1H) ~ 8.4 Hz. In the spectrum of 5, the signals of the
2 | RESULTS AND DISCUSSION
2.1 | Synthesis of Allyl molybdenum
precursors
Allyl
molybdenum
compounds
[(η3‐C3H5)(η5‐
C5H4CH2C6H4X‐4)Mo(CO)2] (5: X = F; 6: X = Cl; 7:
X = Br) were prepared by reaction of appropriate substituted
lithium cyclopentadienide Li(C5H4CH2C6H4X‐4) (1‐Li:
X = F; 2‐Li: X = Cl; 3‐Li: X = Br) with [(η3‐C3H5)
4
benzene protons are split by 19F (3J = 8.7 Hz, J = 5.4 Hz).
The 19F{1H} NMR spectrum of 5 shows a single resonance
at 116.4 ppm.
2.2 | Synthesis of Phenanthroline complexes
The allyl compounds 5–7 react with tetrafluoroboric acid in
the presence of acetonitrile to give stable cationic complexes
[(η5‐C5H4CH2C6H4X‐4)Mo(CO)2(NCMe)2][BF4] (8: X = F;
9: X = Cl; 10: X = Br). The infrared spectra of compounds
8–10 show the CO stretching bands at considerably higher
wavenumbers than those of the allyl precursors 5–7
(Table 1). This shift is due to much lower electron density
on the central metal in cationic compounds 8–10. The
SCHEME
1
Synthesis of compounds 1–3 and molybdenum
compounds 5–7. Reaction conditions: (a) C5H6, pyrrolidine/MeOH;
(b) Li[Et3BH]/Et2O, [(η3‐C3H5)Mo(CO)2(NCMe)2Cl] (4)/
tetrahydrofuran
TABLE 1 Summary of infrared data for molybdenum compoundsa
νa(C≡O)
νs(C≡O)
νa(C≡O)
νs(C≡O)
5
6
1932
1941
1936
1971
1976
1975
1966
1970
1844
1854
1846
1903
1895
1893
1885
1898
13
14
15
16
17
18
19
1968
1966
1966
1966
1967
1967
1966
1896
1885
1885
1886
1888
1889
1885
7
8
9
10
11
12
aWavenumbers are given in cm−1
.

HONZÍČKOVÁ ET AL.
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cationic character of 8–10 is further supported by a broad
B─F stretching band at ca 1040 cm−1. 1H NMR spectra show
two apparent triplets of cyclopentadienyl protons at 5.7 and
4
5.5 ppm (3J = J = 2.2 Hz). A signal at ca 2.5 ppm is
assigned to protons of coordinated acetonitrile. The
FIGURE
2
ORTEP
drawing
of
[(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(phen)]+ present in crystal structure of 11. The labelling for
all non‐hydrogen atoms is shown. Thermal ellipsoids are drawn at the
20% probability level. The alternate position of disordered substituent of
the cyclopentadienyl ring is omitted for clarity
FIGURE
1
ORTEP
drawing
of
[(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(NCMe)2]+ present in crystal structure of 8. Thermal
ellipsoids are drawn at the 30% probability level
FIGURE
3
ORTEP drawing of [(η5‐C5H4CH2C6H4Cl‐4)
SCHEME
2
Synthesis of cationic molybdenum compounds.
Mo(CO)2(phen)]+ present in crystal structure of 12. Thermal ellipsoids
Reaction conditions: (a) HBF4⋅Et2O/CH2Cl2, MeCN; (b) N,NL/CH2Cl2
are drawn at the 30% probability level

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HONZÍČKOVÁ ET AL.
cyclopentadienyl ring substituents exhibit very similar 1H
NMR and 19F{1H} NMR spectral features as described above
for allyl complexes 5–7.
The structure of 8 was determined using single‐crystal X‐
ray diffraction analysis. The cation has a square‐pyramidal
structure with the η5‐cyclopentadienyl ligand in the apical
position (Figure 1). The equatorial plane is occupied with
two cis‐coordinated terminal carbonyl ligands and two nitro-
gen donor atoms of coordinated acetonitrile molecules.
The acetonitrile complexes 8–10 are the key
intermediates for the synthesis of stable derivatives
bearing chelating ligands. The compounds with substituted
1,10‐phenanthroline
ligands
[(η5‐C5H4CH2C6H4X‐4)
Mo(CO)2(N,NL)][BF4] (11–19) are available via ligand‐
exchange reaction (Scheme 2). The reaction products were
characterized using infrared and NMR spectroscopies. The
exchange of the acetonitrile ligands with N,N‐chelating
ligands has only a minor effect on the carbonyl stretching fre-
quencies. Molecular structures of 11, 12, 13 and
18⋅Ph2phen⋅HBF4 in the solid state were determined using
single‐crystal X‐ray diffraction analysis. Molecular structures
of the complex cations are depicted in Figures 2–5. Selected
geometric parameters describing the coordination sphere of
FIGURE
5
ORTEP drawing of [(η5‐C5H4CH2C6H4Cl‐4)
Mo(CO)2(4,7‐Ph2‐phen)]+ present in crystal structure of
18⋅phen⋅HBF4. Thermal ellipsoids are drawn at the 30% probability
level
molybdenum are summarized in Table 2. Due to the geometric
constraint imposed by five‐membered chelate ring, compounds
11, 12, 13 and 18 exhibit more acute N–Mo–N angle
(73.69(11)–74.11(9)°) than the bisacetonitrile complex 8
(77.34(19)°). This phenanthroline‐imposed feature is the only
significant structural difference in the coordination geometries
at the molybdenum centres of 11, 12, 13 and 18 relative that in 8.
The crystal structures of 12 and 13 are stabilized by π–π
interactions. A sandwich π–π stacking, involving the
phenanthroline ligand and the halogeno‐substituted benzene
ring, connects neighbouring molecules into zigzag chains.
The perpendicular distances between centroid of the benzene
ring (C7–C12) and central ring of phenanthroline (C13–C21)
are 3.4815(16) and 3.452(2) Å for compounds 12 and 13,
respectively. Such zigzag chains are crosslinked into layers
through T‐shaped interactions between halide of the C6H5X
moiety and a face of the phenanthroline ligand. The perpen-
dicular distances between halide and side ring of
phenanthroline (N2–C24) are 3.466 and 3.446 Å for com-
pounds 12 and 13, respectively.
FIGURE
4
ORTEP drawing of [(η5‐C5H4CH2C6H4Br‐4)
Mo(CO)2(phen)]+ present in crystal structure of 13. Thermal ellipsoids
In the crystal structure of 18·phen·HBF4, a weak
N─H···F─BF3 hydrogen bond (N···F = 2.774(4) Å) connects
are drawn at the 30% probability level

HONZÍČKOVÁ ET AL.
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TABLE 2 Selected bond lengths and bond angles of molybdenum compoundsa
8
11
1.995(3)
12
13
1.984(3)
18·Ph2phen·HBF4
Mo–Cg(C5)b
Mo–C(CO)
Mo–N
1.984(2)
1.9823(16)
1.9817(15)
1.966(5) 1.967(5)
2.174(5) 2.160(5)
73.3(2)
1.967(6) 1.981(7)
2.187(5) 2.194(4)
76.1(3)
1.969(3) 1.984(4)
2.175(2) 2.194(2)
75.25(15)
1.982(5) 1.983(6)
2.195(5) 2.190(4)
75.7(3)
1.964(4) 1.968(4)
2.178(3) 1.179(3)
75.90(15)
(OC)C–Mo–C(CO)
N–Mo–N
77.34(19)
73.72(18)
74.11(9)
74.0(2)
73.69(11)
aDistances are given in Å; angles and dihedral angles are given in °.
bCg(C5) is centre of gravity of the cyclopentadienyl ring.
the protonated phenanthroline with one tetrafluoroborate.
The phenanthroline molecule is further connected with a
C6H5Cl moiety of the molybdenum complex via sandwich
π–π stacking (Cg(C7–C12)–Pl(39–47) = 3.4011(16) Å).
The highest cytotoxicity is observed for compounds bearing
4,7‐diphenyl‐1,10‐phenanthroline and cyclopentadienyl
ligand modified by 4‐fluorobenzyl (17) and 4‐chlorobenzyl
(18). These species have about one order of magnitude higher
activity than that reported for DDP.
2.3 | Cytotoxicity study
3 | CONCLUSIONS
The cytotoxic activity of phenanthroline molybdenum com-
pounds 11–19 was evaluated on human T‐lymphocytic
MOLT‐4 leukaemia cells using procedures described previ-
ously.[18] All new phenanthroline molybdenum complexes
display high cytotoxic activity against MOLT‐4 leukaemia
cells as evidenced by IC50 values obtained using standard
WST‐1 viability assays (Table 3).
The activity strongly depends on the substitution pattern
of the phenanthroline framework. Very high activity is
observed mainly for complexes with coordinated 5‐NH2‐
phen (14–16: IC50 = 1.9–3.7 μmol l−1) and 4,7‐Ph2‐phen
(17–19: IC50 = 0.9–1.9 μmol l−1). Complexes bearing
unsubstituted 1,10‐phenanthroline show lower activity
(11–13: IC50 = 14.1–16.2 μmol l−1) but even here the IC50
values are comparable with that of cisplatin (DDP;
IC50 = 15.8 Æ 1.9 μmol l−1). The substitution in the
cyclopentadienyl ligand has only a minor effect on
cytotoxicity. Hence, complexes bearing unsubstituted 1,10‐
phenathroline have IC50 values near to that of the analogue
with unsubstituted cyclopentadienyl ring [(η5‐C5H5)
Mo(CO)2(phen)][BF4] (20; IC50 = 19.9 Æ 0.7 μmol l−1).[7]
This study demonstrates that introduction of substituents to
the phenanthroline and cyclopentadienyl ligands of [(η5‐
C5H5)Mo(CO)2(phen)][BF4] results in complexes with var-
ied cytotoxicity. The activity towards MOLT‐4 leukaemia
cells exhibited by complexes bearing 4,7‐Ph2‐phen (17–
19) is roughly ten times greater than that of DDP. Com-
plexes with 5‐NH2‐phen (14–16) are less active than 17–
19 but still an improvement over DDP. Complexes 11–13
with unsubstituted phenanthroline show activities very sim-
ilar to that of DDP. The presence of pendant CH2C6H4X
(X = F, Cl, Br) cyclopentadienyl substituents in 11–19
results in small differences in activity for complexes with
a given N,N‐ligand. While the modulation of X within
complexes 11–13, 14–16 and 17–19 offers little advantage
in terms of cytotoxicity enhancement, these functional
groups provide a convenient entry point for pendant group
elaboration to further explore the cytotoxicity of complexes
with the [(η5‐C5H5)Mo(CO)2(phen)]+ core. The successful
attachment of CH2C6H4X group is also important from
the synthetic point of view. It could be utilized for
post‐modification of molybdenum species using C─C
cross‐coupling reactions.[19,20]
TABLE 3 Cytotoxicity data for complexes bearing N,N‐chelating
ligandsa
IC50
IC50
IC50
4 | EXPERIMENTAL
11
12
13
20
16.2 Æ 0.5
14.5 Æ 0.9
14.1 Æ 1.1
19.9 Æ 0.7
14
1.9 Æ 0.4
3.7 Æ 0.5
2.8 Æ 0.2
15.8 Æ 1.9b
17
18
19
1.4 Æ 0.1
0.9 Æ 0.1
1.9 Æ 0.2
15
4.1 | Methods and materials
16
All operations were performed under nitrogen using conven-
tional Schlenk‐line techniques. The solvents were purified
and dried by standard methods.[21] Starting materials were
available commercially or prepared according to literature
DDP
aIC50 values towards MOLT‐4 cell line are given in μmol l−1
bData published elsewhere.[30]
.

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HONZÍČKOVÁ ET AL.
procedures: [(η3‐C3H5)Mo(CO)2(NCMe)2Cl] (4).[15] The
infrared spectra were recorded in the 400–4000 cm−1 region
(resolution of 1 cm−1) with a Nicolet iS50 FT‐IR spectrome-
ter using a Diamond Smart Orbit ATR. 1H NMR and
19F{1H} NMR spectra were measured with a Bruker Avance
400 spectrometer at room temperature. The chemical shifts
are given in ppm relative to tetramethylsilane. Elemental
analysis (C, H, N) was performed using a Flash 2000 CHNS
elemental analyser (Thermo Scientific).
(Rf,TLC = 0.75). Yield: 5.36 g (23 mmol, 46%), Red oil. Ana-
lytical and spectroscopic data are in agreement those reported
elsewhere.[23]
4.3 | Synthesis of molybdenum compounds
4.3.1 | Synthesis of [(η3‐C3H5)(η5‐
C5H4CH2C6H4F‐4)Mo(CO)2] (5)
A solution of 1 (0.28 g, 1.61 mmol) was dissolved in
diethyl ether (10 ml) and treated with a solution of
SuperHydride (1 M in tetrahydrofuran (THF), 1.65 ml,
1.65 mmol). The reaction mixture was stirred overnight.
The white precipitate was decanted, washed with diethyl
ether (3 × 5 ml) and vacuum dried. The white solid
was dissolved in THF (10 ml) and added to the solution
of 4 (0.50 g, 1.61 mmol) in THF (10 ml) precooled at
−80 °C. The reaction mixture was stirred at room tem-
perature overnight and then vacuum evaporated to dry-
ness. The crude product was extracted with hot hexane
(3 × 10 ml). The volatiles were vacuum evaporated.
The product was recrystallized from a hexane–diethyl
ether (2:1) mixture at −80 °C. Yield: 440 mg (75%,
1.21 mmol). Yellow viscous oil. Anal. Calcd for
C17H15FMoO2 (%): C, 55.75; H, 4.13. Found (%): C,
55.68; H, 4.21. 1H NMR (CDCl3; 400 MHz; δ, ppm):
7.12 (dd, 3J(1H,1H) = 8.1 Hz, 4J(1H,19F) = 5.4 Hz,
4.2 | Synthesis of ligand precursors
4.2.1 | Synthesis of 6‐(4′‐fluorophenyl)fulvene
(1)
Pyrrolidine (6 ml, 73 mmol) was added dropwise to a mixture
of freshly cracked cyclopentadiene (10 ml, 119 mmol) and 4‐
fluorobenzaldehyde (6.45 g, 52 mmol) in methanol (150 ml).
After addition, the solution was stirred at room temperature
for 2 h. The reaction was quenched by a solution of acetic
acid (4 ml, 70 mmol) in distilled water (50 ml). The mixture
was extracted using pentane (3 × 50 ml), and the organic
phases were collected and dried with anhydrous magnesium
sulfate. Volatiles were vacuum‐evaporated and the crude
product was purified by column chromatography on silica
using a hexane–diethyl ether (1:1) mixture as the eluent.
Yield: 5.10 g (30 mmol, 57%). Orange solid. Analytical and
spectroscopic data are in agreement with those reported
elsewhere.[22]
2H, C6H4), 6.97 (dd, 3J(1H,1H)
=
8.1 Hz,
3J(1H,19F) = 8.7 Hz, 2H, C6H4), 5.13 (s, 4H, C5H4), 3.91
3
3
(tt, J(1H,1H) = 10.7 Hz, J(1H,1H) = 7.0 Hz, 1H, meso‐
C3H5), 3.56 (s, 2H, C5H4CH2C6H4F), 2.71 (d,
3J(1H,1H)
=
7.0 Hz, 2H, syn‐C3H5), 0.94 (d,
4.2.2 | Synthesis of 6‐(4′‐chlorophenyl)fulvene
(2)
3J(1H,1H) = 10.7 Hz, 2H, anti‐C3H5). 19F{1H} NMR
(CDCl3; 376 MHz; δ, ppm): −116.4 (C6H4F). FT‐IR
(ATR; cm−1): 1932 vs (νa(CO)), 1844 vs (νs(CO)).
The steps of synthesis followed the procedure for compound
1. Reagents: freshly cracked cyclopentadiene (10 ml,
119 mmol), 4‐chlorobenzaldehyde (7.31 g, 50 mmol), pyrrol-
idine (6 ml, 73 mmol), acetic acid (4 ml, 70 mmol). The
crude product was purified by column chromatography on
silica using a hexane–diethyl ether (1:1) mixture as the eluent
(Rf,TLC = 0.75). Yield: 7.92 g (42 mmol, 60%). Red oil. Ana-
lytical and spectroscopic data are in agreement with those
reported elsewhere.[23,24]
4.3.2 | Synthesis of [(η3‐C3H5)(η5‐
C5H4CH2C6H4Cl‐4)Mo(CO)2] (6)
The steps of synthesis followed the procedure for compound
5. Reagents: 4 (0.50 g, 1.61 mmol), 2 (0.30 g, 1.61 mmol),
Super‐Hydride (1 M in THF, 1.65 ml, 1.65 mmol). Yield:
460 mg (59%, 0.95 mmol). Yellow powder. M.p. 50–60 °C.
Anal. Calcd for C17H15ClMoO2 (%): C, 53.35; H, 3.95.
4.2.3 | Synthesis of 6‐(4′‐bromophenyl)fulvene
(3)
1
Found (%): C, 53.26; H, 4.03. H NMR (CDCl3; 400 MHz;
δ, ppm): 7.25 (d, J(1H,1H) = 8.2 Hz, 2H, C6H4), 7.10 (d,
3
The steps of synthesis followed the procedure for compound
1. Reagents: freshly cracked cyclopentadiene (10 ml,
119 mmol), 4‐bromobenzaldehyde (9.21 g, 50 mmol), pyr-
rolidine (6 ml, 73 mmol), acetic acid (4 ml, 70 mmol). The
crude product was purified by column chromatography on
silica using a hexane–diethyl ether (1:1) mixture as the eluent
3J(1H,1H) = 8.2 Hz, 2H, C6H4), 5.13 (s, 4H, C5H4), 3.91
(tt, 3J(1H,1H) = 10.7 Hz, 3J(1H,1H) = 7.0 Hz, 1H,
meso‐C3H5), 3.56 (s, 2H, C5H4CH2C6H4Cl), 2.71 (d,
3J(1H,1H)
=
7.0 Hz, 2H, syn‐C3H5), 0.94 (d,
3J(1H,1H) = 10.8 Hz, 2H, anti‐C3H5). FT‐IR (ATR; cm−1):
1941 vs (νa(CO)), 1854 vs (νs(CO)).

HONZÍČKOVÁ ET AL.
7 of 10
400 MHz; δ, ppm): 7.28 (d, 3J(1H,1H) = 8.4 Hz, 2H,
4.3.3 | Synthesis of [(η3‐C3H5)(η5‐
C5H4CH2C6H4Br‐4)Mo(CO)2] (7)
3
C6H4), 7.20 (d, J(1H,1H) = 8.4 Hz, 2H, C6H4), 5.63 (dd,
3J(1H,1H)
=
4J(1H,1H)
=
2H, C5H4), 5.49 (dd,
The steps of synthesis followed the procedure for compound
5. Reagents: 4 (0.50 g, 1.61 mmol), 3 (0.38 g, 1.61 mmol),
Super‐Hydride (1 M in THF, 1.65 ml, 1.65 mmol). Yield:
450 mg (65%, 1.05 mmol). Yellow powder. M.p. 70–80 °C.
Anal. Calcd for C17H15BrMoO2 (%): C, 47.80; H, 3.54.
3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H, C5H4), 3.57 (s,
2H, C5H4CH2C6H4Cl), 2.52 (s, 6H, CH3CN). FT‐IR
(ATR; cm−1): 1976 vs (νa(CO)), 1895 vs (νs(CO)), 1040
vs‐br (ν(BF)).
1
Found (%): C, 48.02; H, 3.49. H NMR (CDCl3; 400 MHz;
3
δ, ppm): 7.40 (d, J(1H,1H) = 8.3 Hz, 2H, C6H4), 7.04 (d,
4.3.6 | Synthesis of [(η5‐C5H4CH2C6H4Br‐4)
Mo(CO)2(NCMe)2][BF4] (10)
3J(1H,1H) = 8.3 Hz, 2H, C6H4), 5.13 (s, 4H, C5H4), 3.91
3
3
(tt, J(1H,1H) = 10.8 Hz, J(1H,1H) = 7.0 Hz, 1H, meso‐
C3H5), 3.54 (s, 2H, C5H4CH2C6H4Br), 2.72 (d,
The steps of synthesis followed the procedure for com-
pound 8. Reagents: 7 (428 mg, 1.00 mmol), HBF4·Et2O
(136 μl, 1.00 mmol). Yield: 502 mg (90%, 0.90 mmol).
Dark orange powder. M.p. 120–130 °C (dec.). Anal. Calcd
for C18H16BBrF4MoN2O2 (%): C, 38.95; H, 2.91; N, 5.05.
Found (%): C, 39.02; H, 2.83; N, 5.12. 1H NMR
3J(1H,1H)
=
7.0 Hz, 2H, syn‐C3H5), 0.94 (d,
3J(1H,1H) = 10.8 Hz, 2H, anti‐C3H5). FT‐IR (ATR; cm−1):
1936 vs (νa(CO)), 1846 vs (νs(CO)).
4.3.4 | Synthesis of [(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(NCMe)2][BF4] (8)
3
(CD3CN; 400 MHz; δ, ppm): 7.55 (d, J(1H,1H) = 8.4 Hz,
2H, C6H4), 7.28 (d, 3J(1H,1H) = 8.4 Hz, 2H, C6H4),
5.79 (dd, 3J(1H,1H) = 4J(1H,1H) = 2H, C5H4), 5.57
(dd, 3J(1H,1H) = 4J(1H,1H) = 2H, C5H4), 3.60 (s,
2H, C5H4CH2C6H4Br), 2.49 (s, 6H, CH3CN). FT‐IR
(ATR; cm−1): 1975 vs (νa(CO)), 1893 vs (νs(CO)),
1040 vs‐br (ν(BF)).
Compound 5 (366 mg, 1.00 mmol) was dissolved in 10 ml
of a CH2Cl2–MeCN mixture (10:1), cooled at 0 °C and
treated with HBF4·Et2O (136 μl, 1.00 mmol). The solution
immediately changed colour from yellow to dark red. The
reaction mixture was slowly warmed to room temperature
and stirred for an additional 2 h. The volatiles were vacuum
evaporated. The crude product was washed with Et2O
(5 ml), recrystallized from a MeCN–Et2O mixture and vac-
uum dried. Yield: 456 mg (92%, 0.92 mmol). Dark orange
powder. M.p. 120–130 °C (dec.). Anal. Calcd for
C18H16BF5MoN2O2 (%): C, 43.76; H, 3.26; N, 5.67. Found
(%): C, 43.81; H, 3.18; N, 5.72. 1H NMR (CD3CN;
400 MHz; δ, ppm): 7.32 (dd, 3J(1H,1H) = 8.9 Hz,
4.3.7 | Synthesis of [(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(phen)][BF4] (11)
Compound 8 (99 mg, 0.20 mmol) was dissolved in CH2Cl2
(10 ml) and treated with 1,10‐phenanthroline (36 mg,
0.20 mmol). The solution was stirred at room temperature
overnight. The volatiles were vacuum evaporated. The crude
product was washed with ether and recrystallized from a
CH2Cl2–Et2O mixture and vacuum dried. Yield: 112 mg
(95%, 0.19 mmol). Red powder. M.p. 150–160 °C (dec.).
Anal. Calcd for C26H18BF5MoN2O2 (%): C, 52.73; H, 3.06;
4J(1H,19F)
=
5.4 Hz, 2H, C6H4), 7.10 (dd,
3
3J(1H,1H) = 8.9 Hz, J(1H,19F) = 8.9 Hz, 2H, C6H4), 5.75
(dd, 3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H, C5H4), 5.53
3
4
(dd, J(1H,1H) = J(1H,1H) = 2.2 Hz, 2H, C5H4), 3.58 (s,
2H, C5H4CH2C6H4F), 2.46 (s, 6H, CH3CN). 19F{1H}
NMR (CD3CN; 376 MHz; δ, ppm): −117.7 (C6H4F),
−151.6 (BF4). FT‐IR (ATR; cm−1): 1971 vs (νa(CO)),
1903 vs (νs(CO)), 1040 vs‐br (ν(BF)). Single crystals of 8
suitable for X‐ray diffraction analysis were prepared by
overlayering of the MeCN solution with Et2O.
1
N, 4.73. Found (%): C, 52.82; H, 2.98; N, 4.79. H NMR
3
(CD3CN; 400 MHz; δ, ppm): 9.42 (d, J(1H,1H) = 5.4 Hz,
3
2H, C12H8N2), 8.78 (d, J(1H,1H) = 8.2 Hz, 2H, C12H8N2),
8.22 (s, 2H, C12H8N2), 7.97 (dd, 3J(1H,1H) = 8.2 Hz,
3J(1H,1H)
=
5.4 Hz, 2H, C12H8N2), 6.88 (dd,
4
3J(1H,1H) = 8.9 Hz, J(1H,19F) = 5.4 Hz, 2H, C6H4), 6.86
3
3
(dd, J(1H,1H) = 8.9 Hz, J(1H,19F) = 8.9 Hz, 2H, C6H4),
5.78 (dd, 3J(1H,1H) = 4J(1H,1H) = 2.1 Hz, 2H, C5H4),
5.70 (dd, 3J(1H,1H) = 4J(1H,1H) = 2.1 Hz, 2H, C5H4),
2.97 (s, 2H, C5H4CH2C6H4F). 19F{1H} NMR (CD3CN
376 MHz; δ, ppm): −117.8 (C6H4F), −151.6 (BF4). FT‐IR
(ATR; cm−1): 1966 vs (νa(CO)), 1885 vs (νs(CO)), 1040 vs‐
br (ν(BF)). Single crystals of 11 suitable for X‐ray diffraction
analysis were prepared by overlayering of the CH2Cl2 solu-
tion with hexane.
4.3.5 | Synthesis of [(η5‐C5H4CH2C6H4Cl‐4)
Mo(CO)2(NCMe)2][BF4] (9)
The steps of synthesis followed the procedure for com-
pound 8. Reagents: 6 (383 mg, 1.00 mmol), HBF4·Et2O
(136 μl, 1.00 mmol). Yield: 439 mg (86%, 0.86 mmol).
Dark orange powder. M.p. 120–130 °C (dec.). Anal. Calcd
for C18H16BClF4MoN2O2 (%): C, 42.35; H, 3.16; N, 5.49.
1
Found (%): C, 42.32; H, 3.21; N, 5.57. H NMR (CDCl3;

8 of 10
HONZÍČKOVÁ ET AL.
C12H7N2), 9.03 (d, 3J(1H,1H) = 5.4 Hz, 1H, C12H7N2),
8.77 (d, 3J(1H,1H) = 8.4 Hz, 1H, C12H7N2), 8.37 (d,
4.3.8 | Synthesis of [(η5‐C5H4CH2C6H4Cl‐4)
Mo(CO)2(phen)][BF4] (12)
3J(1H,1H)
=
8.3 Hz, 1H, C12H7N2), 7.92 (dd,
The steps of synthesis followed the procedure for compound
11. Reagents: 9 (102 mg, 0.20 mmol), 1,10‐phenanthroline
(36 mg, 0.20 mmol). Yield: 98 mg (81%, 0.16 mmol). Red
powder. M.p. 150–160 °C (dec.). Anal. Calcd for
C26H18BClF4MoN2O2 (%): C, 51.31; H, 2.98; N, 4.60.
3J(1H,1H) = 8.4 Hz, J(1H,1H) = 5.4 Hz, 1H, C12H7N2),
7.73 (dd, 3J(1H,1H) = 8.3 Hz, 3J(1H,1H) = 5.3 Hz, 1H,
C12H7N2), 7.15 (s, 1H, C12H7N2), 6.88 (s‐br, 2H, C6H4),
6.86 (s‐br, 2H, C6H4), 5.73 (m, 2H, C5H4), 5.67 (m, 1H,
C5H4), 5.65 (m, 1H, C5H4), 5.60 (s, 2H, NH2), 2.94 (s, 2H,
C5H4CH2C6H4F). 19F{1H} NMR (CD3CN; 376 MHz; δ,
ppm): −117.8 (C6H4F), −151.7 (BF4). FT‐IR (ATR; cm−1):
3382 m (ν(NH)), 1966 vs (νa(CO)), 1885 vs (νs(CO)), 1040
vs‐br (ν(BF)).
3
1
Found (%): C, 51.39; H, 3.06; N, 4.51. H NMR (CD3CN;
400 MHz; δ, ppm): 9.41 (d, 3J(1H,1H) = 5.5 Hz, 2H,
C12H8N2), 8.78 (d, 3J(1H,1H) = 8.3 Hz, 2H, C12H8N2),
8.22 (s, 2H, C12H8N2), 7.97 (dd, 3J(1H,1H) = 8.3 Hz,
3J(1H,1H)
=
5.5 Hz, 2H, C12H8N2), 7.11 (d,
3J(1H,1H) = 8.6 Hz, 2H, C6H4), 6.85 (d, 3J(1H,1H) = 8.6 Hz,
4.3.11 | Synthesis of [(η5‐C5H4CH2C6H4Cl‐4)
Mo(CO)2(5‐NH2‐phen)][BF4] (15)
2H, C6H4), 5.80 (dd, J(1H,1H) = J(1H,1H) = 2.1 Hz, 2H,
C5H4), 5.70 (dd, 3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H,
C5H4), 2.99 (s, 2H, C5H4CH2C6H4Cl). FT‐IR (ATR; cm−1):
1970 vs (νa(CO)), 1898 vs (νs(CO)), 1040 vs‐br (ν(BF)). Sin-
gle crystals of 12 suitable for X‐ray diffraction analysis were
prepared by overlayering of the CH2Cl2 solution with hexane.
3
4
The steps of synthesis followed the procedure for compound
11. Reagents: 9 (102 mg, 0.20 mmol), 1,10‐phenanthrolin‐5‐
amine (39 mg, 0.20 mmol). Yield: 117 mg (94%, 0.19 mmol).
Red powder. M.p. 150–160 °C (dec.). Anal. Calcd for
C26H19BClF4MoN3O2 (%): C, 50.07; H, 3.07; N, 6.74.
1
4.3.9 | Synthesis of [(η5‐C5H4CH2C6H4Br‐4)
Mo(CO)2(phen)][BF4] (13)
Found (%): C, 50.15; H, 2.98; N, 6.67. H NMR (CD3CN;
400 MHz; δ, ppm): 9.38 (d, 3J(1H,1H) = 5.4 Hz, 1H,
C12H7N2), 9.02 (d, 3J(1H,1H) = 5.3 Hz, 1H, C12H7N2),
8.77 (d, 3J(1H,1H) = 8.4 Hz, 1H, C12H7N2), 8.37 (d,
The steps of synthesis followed the procedure for compound
11. Reagents: 10 (111 mg, 0.20 mmol), 1,10‐phenanthroline
(36 mg, 0.20 mmol). Yield: 121 mg (92%, 0.18 mmol). Red
powder. M.p. 150–160 °C (dec.). Anal. Calcd for
C26H18BBrF4MoN2O2 (%): C, 47.82; H, 2.78; N, 4.29.
3J(1H,1H)
=
8.3 Hz, 1H, C12H7N2), 7.92 (dd,
3J(1H,1H) = 8.4 Hz, J(1H,1H) = 5.4 Hz, 1H, C12H7N2),
7.73 (dd, 3J(1H,1H) = 8.3 Hz, 3J(1H,1H) = 5.3 Hz, 1H,
C12H7N2), 7.15 (s, 1H, C12H7N2), 7.12 (d, 3J(1H,1H) = 8.5 Hz,
2H, C6H4), 6.84 (d, 3J(1H,1H) = 8.5 Hz, 2H, C6H4), 5.75 (m,
2H, C5H4), 5.68 (m, 1H, C5H4), 5.65 (m, 1H, C5H4), 5.57 (s,
2H, NH2), 2.96 (s, 2H, C5H4CH2C6H4Cl). FT‐IR (ATR; cm
−1): 3384 m (ν(NH)), 1966 vs (νa(CO)), 1885 vs (νs(CO)),
1040 vs‐br (ν(BF)).
3
1
Found (%): C, 47.78; H, 2.75; N, 4.38. H NMR (CD3CN;
400 MHz; δ, ppm): 9.41 (d, 3J(1H,1H) = 5.4 Hz, 2H,
C12H8N2), 8.77 (d, 3J(1H,1H) = 8.2 Hz, 2H, C12H8N2),
8.21 (s, 2H, C12H8N2), 7.97 (dd, 3J(1H,1H) = 8.2 Hz,
3J(1H,1H)
=
5.4 Hz, 2H, C12H8N2), 7.24 (d,
3J(1H,1H) = 8.4 Hz, 2H, C6H4), 6.77 (d, 3J(1H,1H) = 8.4 Hz,
2H, C6H4), 5.80 (dd, J(1H,1H) = J(1H,1H) = 2.2 Hz, 2H,
C5H4), 5.69 (dd, 3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H,
C5H4), 2.97 (s, 2H, C5H4CH2C6H4Br). FT‐IR (ATR; cm
−1): 1968 vs (νa(CO)), 1896 vs (νs(CO)), 1040 vs‐br
(ν(BF)). Single crystals of 13 suitable for X‐ray diffraction
analysis were prepared by overlayering of the CH2Cl2 solu-
tion with hexane.
3
4
4.3.12 | Synthesis of [(η5‐C5H4CH2C6H4Br‐4)
Mo(CO)2(5‐NH2‐phen)][BF4] (16)
The steps of synthesis followed the procedure for compound
11. Reagents: 10 (111 mg, 0.20 mmol), 1,10‐phenanthrolin‐
5‐amine (39 mg, 0.20 mmol). Yield: 125 mg (94%,
0.19 mmol). Red powder. M.p. 150–160 °C (dec.). Anal.
Calcd for C26H19BBrF4MoN3O2 (%): C, 46.74; H, 2.87; N,
6.29. Found (%): C, 46.62; H, 2.80; N, 6.36. 1H NMR
4.3.10 | Synthesis of [(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(5‐NH2‐phen)][BF4] (14)
3
(CD3CN; 400 MHz; δ, ppm): 9.37 (d, J(1H,1H) = 5.4 Hz,
3
1H, C12H7N2), 9.02 (d, J(1H,1H) = 5.4 Hz, 1H, C12H7N2),
The steps of synthesis followed the procedure for compound
11. Reagents: 8 (99 mg, 0.20 mmol), 1,10‐phenanthrolin‐5‐
amine (39 mg, 0.20 mmol). Yield: 116 mg (96%, 0.19 mmol).
Red powder. M.p. 150–160 °C (dec.). Anal. Calcd for
C26H19BF5MoN3O2 (%): C, 51.43; H, 3.15; N, 6.92. Found
(%): C, 51.36; H, 3.21; N, 6.84. 1H NMR (CD3CN;
400 MHz; δ, ppm): 9.38 (d, 3J(1H,1H) = 5.4 Hz, 1H,
8.77 (d, 3J(1H,1H) = 8.4 Hz, 1H, C12H7N2), 8.36 (d,
3J(1H,1H)
=
8.3 Hz, 1H, C12H7N2), 7.92 (dd,
3
3J(1H,1H) = 8.4 Hz, J(1H,1H) = 5.4 Hz, 1H, C12H7N2),
7.72 (dd, 3J(1H,1H) = 8.3 Hz, 3J(1H,1H) = 5.4 Hz, 1H,
C12H7N2), 7.25 (d, J(1H,1H) = 8.5 Hz, 2H, C6H4), 7.15 (s,
3
1H, C12H7N2), 6.77 (d, J(1H.1H) = 8.5 Hz, 2H, C6H4),
3
5.75 (m, 2H, C5H4), 5.67 (m, 1H, C5H4), 5.65 (m, 1H,

HONZÍČKOVÁ ET AL.
9 of 10
C5H4), 5.61 (s, 2H, NH2), 2.94 (s, 2H, C5H4CH2C6H4Br).
FT‐IR (ATR; cm−1): 3385 Mm (ν(NH)), 1966 vs (νa(CO)),
1886 vs (νs(CO)), 1040 vs‐br (ν(BF)).
Calcd for C38H26BBrF4MoN2O2 (%): C, 56.68; H, 3.25; N,
3.48. Found (%): C, 56.62; H, 3.31; N, 3.52. 1H NMR
3
(CD3CN; 400 MHz; δ, ppm): 9.45 (d, J(1H,1H) = 5.6 Hz,
2H, C12H6N2), 8.15 (s, 2H, C12H6N2), 7.93 (d,
3J(1H,1H) = 5.6 Hz, 2H, C12H6N2), 7.67 (s, 10H, C6H5),
7.20 (d, 3J(1H,1H) = 8.4 Hz, 2H, C6H4), 6.77 (d,
4.3.13 | Synthesis of [(η5‐C5H4CH2C6H4F‐4)
Mo(CO)2(4,7‐Ph2‐phen)][BF4] (17)
3J(1H,1H)
=
8.4 Hz, 2H, C6H4), 5.88 (dd,
The steps of synthesis followed the procedure for compound
11. Reagents: 8 (99 mg, 0.20 mmol), 4,7‐diphenyl‐1,10‐
phenanthroline (67 mg, 0.20 mmol). Yield: 145 mg (97%,
0.19 mmol). Red powder. M.p. 150–160 °C (dec.). Anal.
Calcd for C38H26BF5MoN2O2 (%): C, 61.31; H, 3.52; N,
3.76. Found (%): C, 61.24; H, 3.58; N, 3.68. 1H NMR
3J(1H,1H) = 4J(1H,1H) = 2.1 Hz, 2H, C5H4), 5.76 (dd,
3J(1H,1H) = J(1H,1H) = 2.1 Hz, 2H, C5H4), 3.08 (s, 2H,
4
C5H4CH2C6H4Br). FT‐IR (ATR; cm−1): 1966 vs (νa(CO)),
1885 vs (νs(CO)), 1040 vs‐br (ν(BF)).
4.4 | X‐ray crystallography
3
(CD3CN; 400 MHz; δ, ppm): 9.46 (d, J(1H,1H) = 5.6 Hz,
2H, C12H6N2), 8.15 (s, 2H, C12H6N2), 7.93 (d,
3J(1H,1H) = 5.6 Hz, 2H, C12H6N2), 7.67 (s, 10H, C6H5),
7.07 (d, 2H, 3J(1H,1H) = 8.5 Hz, C6H4), 6.85 (d,
The X‐ray data for crystals of compounds 8, 11, 12, 13 and
18·phen·HBF4 were obtained at 150 K using an Oxford
Cryostream low‐temperature device with
a
Nonius
3J(1H,1H)
=
8.5 Hz, 2H, C6H4), 5.88 (dd,
KappaCCD diffractometer with Mo Kα radiation
(λ = 0.71073 Å) and a graphite monochromator. Data reduc-
tions were performed with DENZO‐SMN.[25] The absorption
was corrected by integration methods.[26] Structures were
solved by direct methods (Sir92)[27] and refined by full‐
matrix least squares based on F2 (SHELXL97).[28] Hydrogen
atoms were mostly localized on a difference Fourier map.
However, to ensure uniformity of the treatment of the crystal,
all hydrogen atoms were recalculated into idealized positions
(riding model) and assigned temperature factors
Uiso(H) = 1.2(Ueq(pivot atom)) or 1.5Ueq for the methyl moi-
ety with C─H = 0.96, 0.97 and 0.93 Å for methyl, methylene
and hydrogen atoms in aromatic rings or the allyl moiety,
respectively. The tetrafluoroborate structure within 8 contains
positionally disordered fluorine atoms. Three of the fluorine
atoms were split into two positions with occupancy of
1:1. This disorder has been treated by Shelxl software
instructions.[29] SAME Shelxl software instruction was used
in the case of 11, which contains a disordered benzyl
group. It was split into two positions with occupancy of
about 5:1. The hydrogen atom of the protonated ligand in
18 was localized on the Fourier difference electron density
map close to one of the nitrogen atoms. The N─H distance
was fixed to be 0.92 Å in the appropriate direction for the
N─H···F─BF3 hydrogen bond. CCDC 1511587 (for 8),
1511588 (for 11), 1511589 (for 13), 1511590 (for 12)
and 1511591 (for 18·phen·HBF4) contain the supplemen-
tary crystallographic data for this paper. These data can
be obtained free of charge from the Cambridge Crystallo-
graphic Data Centre.
3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H, C5H4), 5.76 (dd,
4
3J(1H,1H) = J(1H,1H) = 2.2 Hz, 2H, C5H4), 3.09 (s, 2H,
C5H4CH2C6H4F). 19F{1H} NMR (CD3CN; 376 MHz; δ,
ppm): −117.8 (C6H4F), −151.6 (BF4). FT‐IR (ATR; cm−1):
1967 vs (νa(CO)), 1888 vs (νs(CO)), 1040 vs‐br (ν(BF)).
4.3.14 | Synthesis of [(η5‐C5H4CH2C6H4Cl‐4)
Mo(CO)2(4,7‐Ph2‐phen)][BF4] (18)
The steps of synthesis followed the procedure for compound
11. Reagents: 9 (102 mg, 0.20 mmol), 4,7‐diphenyl‐1,10‐
phenanthroline (67 mg, 0.20 mmol). Yield: 142 mg (93%,
0.19 mmol). Red powder. M.p. 150–160 °C (dec.). Anal.
Calcd for C38H26BClF4MoN2O2 (%): C, 59.99; H, 3.44; N,
3.68. Found (%): C, 59.91; H, 3.49; N, 3.72. 1H NMR
3
(CD3CN; 400 MHz; δ, ppm): 9.46 (d, J(1H,1H) = 5.6 Hz,
2H, C12H6N2), 8.15 (s, 2H, C12H6N2), 7.93 (d,
3J(1H,1H) = 5.6 Hz, 2H, C12H6N2), 7.67 (s, 10H, C6H5),
7.07 (d, 3J(1H,1H) = 8.5 Hz, 2H, C6H4), 6.85 (d,
3J(1H,1H)
=
8.5 Hz, 2H, C6H4), 5.88 (dd,
3J(1H,1H) = 4J(1H,1H) = 2.2 Hz, 2H, C5H4), 5.76 (dd,
3J(1H,1H) = J(1H,1H) = 2.2 Hz, 2H, C5H4), 3.09 (s, 2H,
4
C5H4CH2C6H4Cl). FT‐IR (ATR; cm−1): 1967 vs (νa(CO)),
1889 vs (νs(CO)), 1040 vs‐br (ν(BF)). Single crystals of
18·Ph2phen·HBF4 suitable for X‐ray diffraction analysis
were prepared by overlayering of the CH2Cl2 solution of
the crude product with hexane.
4.3.15 | Synthesis of [(η5‐C5H4CH2C6H4Br‐4)
Mo(CO)2(4,7‐Ph2‐phen)][BF4] (19)
The steps of synthesis followed the procedure for compound
11. Reagents: 10 (111 mg, 0.20 mmol), 4,7‐diphenyl‐1,10‐
phenanthroline (67 mg, 0.20 mmol). Yield: 158 mg (98%,
0.20 mmol). Red powder. M.p. 150–160 °C (dec.). Anal.
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