1,3-Dipolar cycloadditions of ruthenium(II) azido complexes with alkynes and nitriles

Article abstract of DOI:10.1021/ic302264t

The diazido complex [Na][Ru(N₃)₂{κ ³(N,N,N)-Tpms}(PPh₃)] (1) (Tpms = tris(pyrazolyl) methanesulfonate) has been synthesized, and its reactivity toward dipolarophiles has been investigated. Thus, the reaction of 1 with alkynes leads to complexes with one or two triazolate ligands depending on the alkyne and the reaction conditions. Complex 1 also reacts with nitriles. Thus, the reaction with RCN (R = Me, Ph) leads to the substitution products [Ru(N₃)(NCR) {κ³(N,N,N)-Tpms}(PPh₃)]. However, when fumaronitrile is used, a complex containing a new κ²(N¹,N ³)-5-(1,2,3-triazol-4-yl)-1,2,3,4-tetrazolate ligand is obtained as the result of two consecutive cycloaddition reactions. The mechanism for this unusual reaction has been unambiguously established through the isolation of the intermediate complex resulting from a first cycloaddition between a coordinated azide and the C=C double bond.

Full text of DOI:10.1021/ic302264t

Article
pubs.acs.org/IC
1,3-Dipolar Cycloadditions of Ruthenium(II) Azido Complexes with
Alkynes and Nitriles
S. Miguel-Fernandez, S. Martínez de Salinas, J. Díez, M. P. Gamasa, and E. Lastra*
́
́ ́ ́
Departamento de Química Organica e Inorganica, Instituto de Química Organometalica “Enrique Moles” (Unidad Asociada al
C.S.I.C.), Universidad de Oviedo, 33006 Oviedo, Principado de Asturias, Spain
S
* Supporting Information
ABSTRACT: The diazido complex [Na][Ru-
(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (Tpms = tris(pyrazolyl)-
methanesulfonate) has been synthesized, and its reactivity
toward dipolarophiles has been investigated. Thus, the reaction
of 1 with alkynes leads to complexes with one or two triazolate
ligands depending on the alkyne and the reaction conditions.
Complex 1 also reacts with nitriles. Thus, the reaction with
RCN (R = Me, Ph) leads to the substitution products
[Ru(N3)(NCR){κ3(N,N,N)-Tpms}(PPh3)]. However, when
fumaronitrile is used, a complex containing a new κ2(N1,N3)-5-
(1,2,3-triazol-4-yl)-1,2,3,4-tetrazolate ligand is obtained as the
result of two consecutive cycloaddition reactions. The
mechanism for this unusual reaction has been unambiguously established through the isolation of the intermediate complex
resulting from a first cycloaddition between a coordinated azide and the CC double bond.
In particular, ruthenium azido complexes have been reported
to react with alkynes to produce triazolato complexes and the
reactions with nitriles and isonitriles produce metal−nitrogen
and metal−carbon bonded tetrazolates respectively.
Our interest in the chemistry of ruthenium complexes lead us
to explore the behavior of azido complexes in the fragment
[Ru{κ3(N,N,N)-Tpms}(PPh3)2] (Tpms = tris(pyrazolyl)-
methanesulfonate). Thus, in this paper we present 1,3-dipolar
cycloadditions of a diazido ruthenium(II) complex with alkynes
and nitriles to give triazolato or tetrazolato complexes
respectively. A ruthenium complex with a new κ2(N1,N3)-5-
(1,2,3-triazol-4-yl)-1,2,3,4-tetrazolate ligand is described and its
X-ray structure is reported.
INTRODUCTION
■
1,3-Dipolar cycloaddition reactions are common processes in
organic chemistry1 which involve the reaction of 1,3-dipoles
with unsaturated dipolarophiles. Among various 1,3-dipoles,
organic azides are particularly important2 as they provide an
entry into the synthesis of triazoles and tetrazoles, which are
interesting organic molecules. In particular, 1,2,3-triazoles have
found a range of important applications in the pharmaceutical
and agricultural industries,3 and the preparation of 5R-
substituted tetrazoles presents a great interest due to the use
of 5R-tetrazole-containing coordination compounds of Pt(II)
and Pt(IV) as cytostatic agents, resulting in a minimization of
the negative effects of platinum anticancer drugs.4
The Huisgen 1,3-dipolar cycloaddition of azides and alkynes5
is one of the most useful synthetic methods leading to these
heterocycles. However, even though the reaction is highly
exothermic (−50 to −65 kcal/mol), its high activation barrier
results in exceedingly low reaction rates for unactivated
reactants even at elevated temperatures. The copper-catalyzed
1,3-dipolar azide−alkyne cycloaddition (CuAAC)6 and more
recently the ruthenium catalyzed 1,3-dipolar azide−alkyne
cycloaddition (RuAAC)7 represent an important advance in
the chemistry of 1,2,3-triazoles.
EXPERIMENTAL SECTION
■
Materials and Instrumentation. All manipulations were
performed under an atmosphere of dry nitrogen using a vacuum-line
and standard Schlenk techniques. All reagents were obtained from
commercial suppliers and used without further purification. Solvents
were dried by standard methods and distilled under nitrogen before
use. The compound [RuCl{κ3(N,N,N)-Tpms}(PPh3)2] was prepared
by previously reported methods.14 Infrared spectra were recorded on a
Perkin-Elmer 1720-XFT spectrometer. The C, H, N, and S analyses
were carried out with a Perkin-Elmer 2400, LECO CHNS-932, and
VTF-900 microanalyzers. Conductivities were measured at room
temperature in ca. 5 × 10−4 mol dm−3 solutions, with a crison EC-
Meter BASIC 30+ conductimeter. Electrospray mass spectra (ESI-MS)
were recorded on a Bruker Esquire 6000 instrument, operating in the
Metal coordinated azido ligands can also undergo 1,3-dipolar
cycloaddition reactions. An excellent review8 was published in
1997 by Fruhauf. To that date, the metals involved in this
̈
chemistry most often were Pd(II), Pt(II), and Co(III) and in
less extension Ni(II), Rh(I), Ir(I), Cu(I), Au(I), and Au(III).
Recently, Mo(II)9 and especially Ru(II)10−13 examples have
been reported.
Received: October 16, 2012
Published: March 29, 2013
© 2013 American Chemical Society
4293
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Inorganic Chemistry
Article
positive or negative mode and using dichloromethane or methanol
solutions. NMR spectra were recorded on a Bruker AV-400 instrument
at 400.1 MHz (1H), 162.1 (31P), or 100.6 MHz (13C) and a Bruker
AV-300 instrument at 300.1 MHz (1H), 75.5 MHz (13C) using SiMe4
or 85% H3PO4 as standards. DEPT experiments were carried out for
all the compounds. Coupling constants J are given in hertz.
Resonances due to the Tpms ligand are reported by chemical shift
acetone: ΛM = 81 S cm2 mol−1. IR (KBr): 2077 (ν(CN)); 1725
(ν(CO)); 1296 and 1092 (ν(S−O)); 834 (ν(C−N)); 622 (ν(C−
1
S)) cm−1. H NMR in acetone-d6 (δ): 9.00 (d, 2H, H3,5 pz), 8.90 (d,
1H, H3,5 pz), 8.18 (d, 1H, H3,5 pz), 7.30 (m, 5H, H3,5 pz and PPh3),
7.13 (m, 6H, PPh3), 6.94 (m, 6H, PPh3), 6.31 (d, 1H, H4 pz), 6.06 (d,
2H, H4 pz), 4.26 (c, 8H, 3JHH = 7.0 Hz, CH2), 1.28 (t, 12H, 3JHH = 7.0
Hz, CH3) ppm. 13C{1H} NMR in acetone-d6 (δ): 162.8 (s, CO),
149.0 (s, C-3,5 pz), 144.2 (s, C-3,5 pz), 139.5 (s, CCO2Et), 136.0 (s,
C-3,5 pz), 135.5 (s, C-3,5 pz), 134.2 (d, 2JCP = 9.0 Hz, PPh3), 133.9 (d,
3
and multiplicity only, since all JHH values for pyrazolyl rings are 2.5
Hz. Abbreviations used: br, broad signal; s, singlet; d, doublet; m,
multiplet; t, triplet. The following atom labels have been used for the
1H and 13C{1H} spectroscopic data of the tris(pyrazolyl)-
methanesulfonate (Tpms) ligand:
2
JCP = 39.0 Hz, C-1 PPh3), 128.9 (s, PPh3), 127.4 (d, JCP = 9.0 Hz,
PPh3), 105.9 (s, C-4 pz), 105.1 (s, C-4 pz), 90.6 (C-SO3), 60.4 (s,
CH2), 13.6 (s, CH3) ppm. 31P NMR in acetone-d6 (δ): 51.9 (s, PPh3)
ppm.
Synthesis of [Na][Ru(N3){N3C2HCO2Me}{κ3(N,N,N)-Tpms}(PPh3)]
(3). Methyl propiolate (117 μL, 1.31 mmol) was added to a solution
of complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100 mg,
0.131 mmol) in acetone (20 mL). The reaction mixture was stirred at
room temperature for
Synthesis of [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1). NaN3 (70
mg, 1.05 mmol) was added to a solution of complex [RuCl-
{κ3(N,N,N)-Tpms}(PPh3)2] (100 mg, 0.105 mmol) in a 1:3
dichloromethane/methanol mixture (20 mL), and the reaction mixture
was heated at 65 °C for 4 h. Solvents were removed under a vacuum,
and the solid residue was extracted with cold acetone. The resulting
solution was filtered through kieselguhr and concentrated under a
vacuum to a volume of approximately 1 mL. Addition of hexane
afforded a yellow precipitate. Solvents were decanted and the solid was
washed with dichloromethane (2 × 20 mL) and hexane (3 × 30 mL)
and dried under reduced pressure. Yield: 52 mg (65%). S20°C (H2O):
6.4 mg/mL. Anal. Calcd. for C28H24N12NaO3PRuS: C, 44.04; H, 3.17;
N, 22.01; S, 4.20. Found: C, 44.23; H, 3.34; N, 21.73; S, 4.01. MS-ESI
(m/z): 741 ([M]−, 100%). Molar conductivity in acetone: ΛM = 89 S
cm2 mol−1. IR (KBr): 2048 (ν(NNN)); 1281 and 1055 (ν(S−
Fifteen hours and a yellow precipitate was formed. Solvents were
decanted, and the solid residue was washed with hexane (3 × 20 mL)
and dried under reduced pressure. Yield = 44 mg (40%). Anal. Calcd.
for C32H28N12NaO5PRuS: C, 45.34; H, 3.33; N, 19.83; S, 3.78. Found:
C, 45.39; H, 3.45; N, 20.06; S, 3.64. MS-ESI (m/z): 825 ([M]−,
100%); 563 ([M-PPh3]−, 48%). Molar conductivity in acetone: ΛM
=
89 S cm2 mol−1. IR (KBr): 2052 (ν(NNN)); 1708 (ν(CO));
1
1295 and 1055 (ν(S−O)); 833 (ν(C−N)); 622 (ν(C−S)) cm−1. H
NMR in acetone-d6 (δ): 9.01 (d, 1H, H3,5 pz), 8.98 (d, 1H, H3,5 pz),
8.89 (d, 1H, H3,5 pz), 7.87 (s, 1H, CH), 7.36 (m, 3H, PPh3), 7.31 (d,
1H, H3,5 pz), 7.21 (m, 7H, PPh3), 6.99 (d, 1H, H3,5 pz), 6.98 (d, 1H,
H
3,5 pz), 6.85 (m, 5H, PPh3), 6.43 (d, 1H, H4 pz), 6.21 (d, 1H, H4 pz),
6.05 (d, 1H, H4 pz), 3.81 (s, 3H, CH3) ppm. 13C{1H} NMR in
acetone-d6 (δ): 163.1 (s, CO), 149.8 (s, C-3,5 pz), 146.9 (s, C-3,5
pz), 138.9 (s, CH), 137.7 (s, CCO2CH3), 136.1 (s, C-3,5 pz), 136.0 (s,
1
O)); 832 (ν(C−N)); 622 (ν(C−S)) cm−1. H NMR in acetone-d6
2
(δ): 8.95 (m, 3H, H3,5 pz), 8.52 (d, 1H, H3,5 pz), 7.42 - 7.25 (m, 15H,
PPh3), 6.70 (d, 2H, H3,5 pz), 6.59 (dd, 1H, H4 pz), 6.01 (dd, 2H, H4
pz) ppm. 13C{1H} NMR in acetone-d6 (δ): 147.1 (s, C-3,5 pz), 143.7
C-3,5 pz), 133.2 (d, JCP = 9.0 Hz, PPh3), 132.7 (s, PPh3), 127.9 (d,
2JCP = 9.0 Hz, PPh3), 106.5 (s, C-4 pz), 106.1 (s, C-4 pz), 91.5 (s, C-
SO3), 52.6 (s, CH3) ppm. 31P NMR in acetone-d6 (δ): 52.5 (s, PPh3)
ppm.
(s, C-3,5 pz), 136.3 (s, C-3,5 pz), 135.2 (s, C-3,5 pz), 133.9 (d, 2JCP
9.0 Hz, PPh3), 129.1 (s, PPh3), 127.8 (d, JCP = 9.0 Hz, PPh3), 106.3
(s, C-4 pz), 106.0 (s, C-4 pz), 90.8 (s, C-SO3) ppm. 31P NMR in
acetone-d6 (δ): 52.5 (s, PPh3) ppm.
=
Synthesis of [Na][Ru{N3C2HCO2Me}2{κ3(N,N,N)-Tpms}(PPh3)] (4).
Methyl propiolate (117 μL, 1.31 mmol) was added to a solution of
complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100 mg,
0.131 mmol) in acetone (30 mL). The reaction mixture was refluxed
for 6 h, and a yellow precipitate was formed. Solvents were decanted
and the solid residue was washed with hexane (3 × 20 mL) and dried
under reduced pressure. Yield =56 mg (46%). Anal. Calcd. for
C36H32N12NaO7PRuS: C, 46.40; H, 3.46; N, 18.04. Found: C, 46.33;
H, 3.78; N, 17.86. MS-ESI (m/z): 909 ([M]−, 100%). Molar
conductivity in methanol: ΛM = 109 S cm2 mol−1. IR (KBr): 2047
(ν(CN)); 1707 (ν(CO)); 1297 and 1055 (ν(S−O)); 748 (ν(C−
2
Synthesis of [Na][Ru{κ(N2)-N3C2(CO2R)2}2{κ3(N,N,N)-Tpms}(PPh3)]
(R = Me (2a), Et (2b)). The corresponding alkyne (1.31 mmol)
(dimethyl acetylenedicarboxylate (DMAD), 158 μL for 2a, diethyl
acetylenedicarboxylate (DEAD), 217 μL for 2b) was added to a
solution of complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1)
(100 mg, 0.131 mmol) in acetone (20 mL). The reaction mixture was
stirred at room temperature for 3 h (for 2a) or 18 h (for 2b). Solvents
were then removed under a vacuum, the solid residue was extracted
with dichloromethane, and the resultant solution was filtered through
kieselguhr and concentrated under vacuum. Addition of hexane
afforded an orange precipitate. Solvents were decanted and the solid
was washed with hexane (3 × 30 mL) and diethyl ether (2 × 20 mL)
and dried under reduced pressure. 2a. Yield: 70 mg (51%). Anal.
Calcd. for C40H36N12NaO11PRuS: C, 45.85; H, 3.46; N, 16.04. Found:
C, 45.91; H, 3.46; N, 15.97. MS-ESI (m/z): 1025 ([M]−, 100%); 763
([M-PPh3]−, 55%). Molar conductivity in acetone: ΛM = 92 S cm2
mol−1. IR (KBr): 2071 (ν(CN)); 1732 (ν(CO)); 1294 and 1092
(ν(S−O)); 833 (ν(C−N)); 622 (ν(C−S)) cm−1. 1H NMR in acetone-
d6 (δ): 9.02 (d, 2H, H3,5 pz), 8.91 (d, 1H, H3,5 pz), 8.02 (d, 1H, H3,5
pz), 7.31 (m, 4H, PPh3), 7.22 (d, 2H, H3,5 pz), 7.13 (m, 5H, PPh3),
6.91 (m, 6H, PPh3), 6.29 (dd, 1H, H4 pz), 6.08 (dd, 2H, H4 pz), 3.79
(s, 12H, CH3) ppm. 13C{1H} NMR in acetone-d6 (δ): 163.0 (s, C
O), 149.0 (s, C-3,5 pz), 144.1 (s, C-3,5 pz), 139.3 (s, CCO2CH3),
1
N)); 623 (ν(C−S)) cm−1. H NMR in acetone-d6 (δ): 9.01 (d, 2H,
H
3,5 pz), 8.95 (d, 1H, H3,5 pz), 7.82 (s, 2H, CH), 7.31 (m, 3H, PPh3),
7.10 (m, 6H, PPh3), 6.91 (d, 2H, H3,5 pz), 6.70 (m, 6H, PPh3), 6.55
(d, 1H, H3,5 pz), 6.32 (d, 1H, H4 pz), 6.15 (d, 2H, H4 pz), 3.77 (s, 6H,
CH3) ppm. 13C{1H} NMR in acetone-d6 (δ): 162.3 (s, CO), 148.8
(s, C-3,5 pz), 143.6 (s, C-3,5 pz), 139.7 (s, CH), 137.4 (s, CCO2CH3),
136.2 (s, C-3,5 pz), 135.3 (s, C-3,5 pz), 133.3 (d, 2JCP = 9.0 Hz, PPh3),
132.8 (d, JCP = 39.0 Hz, C-1 PPh3), 129.2 (s, PPh3), 127.6 (d, JCP
2
=
9.0 Hz, PPh3), 106.9 (s, C-4 pz), 106.2 (s, C-4 pz), 91.4 (s, C-SO3),
50.1 (s, CH3) ppm. 31P NMR in acetone-d6 (δ): 51.5 (s, PPh3) ppm.
Synthesis of [Na][Ru(N3){κ(N)-NCS}{κ3(N,N,N)-Tpms}(PPh3)] (5).
CS2 (35 μL, 0.576 mmol) was added to a solution of complex
[Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100 mg, 0.131 mmol)
in acetone (30 mL), and the mixture was refluxed for 8 h. Solvents
were then removed under a vacuum, and the purple residue was
washed with diethyl ether (3 × 30 mL) and dried under reduced
pressure. Yield: 56 mg (55%). Anal. Calcd. for C29H24N10NaO3PRuS2:
C, 44.67; H, 3.10; N, 17.96; S, 8.22. Found: C, 44.52; H, 3.29; N,
18.05; S, 8.52. MS-ESI (m/z): 757 ([M]−, 48%). Molar conductivity in
acetone: ΛM = 113 S cm2 mol−1. IR (KBr): 2117 (ν(NCS)); 2060
(ν(N3)); 1275 and 1056 (ν(S−O)); 832 (ν(C−N)); 623 (ν(C−S))
136.1 (s, C-3,5 pz), 135.5 (s, C-3,5 pz), 134.2 (d, 2JCP = 9.0 Hz, PPh3),
2
133.8 (d, JCP = 39.0 Hz, C-1 PPh3), 129.0 (s, PPh3), 127.5 (d, JCP
=
9.0 Hz, PPh3), 106.0 (s, C-4 pz), 105.3 (s, C-4 pz), 90.8 (s, C-SO3),
51.2 (s, CH3) ppm. 31P NMR in acetone-d6 (δ): 51.8 (s, PPh3) ppm.
2b. Yield: 77 mg (53%). Anal. Calcd. for C44H44N12NaO11PRuS: C,
47.87; H, 4.02; N, 15.22; S, 2.90. Found: C, 47.81; H, 3.93; N, 15.07;
S, 3.11. MS-ESI (m/z): 1081 ([M]−, 57%). Molar conductivity in
1
cm−1. H NMR in acetone-d6 (δ): 8.95 (m, 3H, H3,5 pz), 7.34−7.30
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Inorganic Chemistry
Article
Table 1. Crystal Data and Structure Refinement for Compounds 2b·2(C3H6O), 7·CH2Cl2, and 9·C4H10O
2b·2(C3H6O)
7·CH2Cl2
9·C4H10O
empirical formula
formula weight
temperature/K
wavelength/Å
crystal system
space group
a/Å
C44H44N12NaO11PRuS, 2(C3H6O)
C30H27N10O3PRuS, (CH2Cl2)
C31H25N13NaO3PRuS, (C4H10O)
1220.16
293(2)
1.5418
triclinic
824.64
150(2)
1.5418
triclinic
888.85
293(2)
1.5418
monoclinic
P21/n
P1
̅
P1
̅
13.3422(3)
14.4554(3)
14.7576(3)
97.852(2)
94.281(2)
98.419(2)
2
8.335(5)
12.319(5)
16.685(5)
84.777(5)
87.554(5)
85.771(5)
2
10.5803(2)
29.3713(3)
12.3860(1)
90
b/Å
c/Å
α/°
β/°
γ/°
Z
93.596(1)
90
4
volume/Å3
calculated density/g cm−3
μ/mm−1
2776.14(10)
1.460
1700.3(13)
1.611
3841.46(9)
1.537
3.606
6.620
4.803
F(000)
1260
836
1816
crystal size/mm
θ range/°
0.02 × 0.015 × 0.01
3.04−74.80
29266
0.025 × 0.015 × 0.01
3.61−74.41
11305
0.03 × 0.02 × 0.01
3.01−74.74
29270
no. of reflns. collected
no. of unique reflns.
completeness to θmax (%)
no. of parameters/restraints
goodness-of-fit on F2
10991 [R(int) = 0.0245]
96.3
6346 [R(int) = 0.0393]
91.2
7657 [R(int) = 0.0361]
97.1
688/3
443/0
507/0
1.0593
1.049
1.020
a
R1 [I > 2σ(I)]
0.0422
0.0460
0.0333
a
wR2 [I > 2σ(I)]
0.1173
0.1181
0.0810
R1 (all data)
0.0455
0.0553
0.0416
wR2 (all data)
0.1209
0.1247
0.0858
largest diff. peak and hole/e Å−3
2.101 and −1.783
2
0.836 and −1.467
0.431 and −0.844
a
R1 = Σ(|Fo| − |Fc|)/Σ|Fo|; wR2 = {Σ[w(Fo − Fc2)2]/Σ[w(Fo )2]}1/2
.
2
(m, 15H, PPh3), 6.74 (d, 1H, H3,5 pz), 6.65 (d, 1H, H3,5 pz), 6.57 (d,
1H, H3,5 pz), 6.10 (d, 1H, H4 pz), 6.07 (d, 1H, H4 pz), 6.03 (d, 1H, H4
pz) ppm. 13C{1H} NMR in acetone-d6 (δ): 147.1 (s, C-3,5 pz), 146.9
(s, C-3,5 pz), 146.7 (s, C-3,5 pz), 136.4 (s, C-3,5 pz), 136.2 (s, C-3,5
mg, 0.131 mmol) in acetonitrile (30 mL) was heated to reflux
temperature for 6 days. After this time period, the solvents were
removed under a vacuum, and the yellow residue was extracted with
dichloromethane and the resultant solution was filtered through
kieselguhr and concentrated under vacuum to a volume of
approximately 1 mL. Addition of hexane afforded a yellow precipitate.
Solvents were decanted and the solid residue was washed with hexane
(3 × 30 mL) and dried under reduced pressure. Yield: 83 mg (86%).
Anal. Calcd. for C30H27N10O3PRuS: C, 48.71; H, 3.68; N, 18.94; S,
4.33. Found: C, 48.50; H, 3.68; N, 19.24; S, 4.25. MS-ESI (m/z): 763
([M + Na]+, 100%). IR (KBr): 2131 (ν(NCMe)); 2036 (ν(N31));
1281 and 1054 (ν(S−O)); 834 (ν(C−N)); 625 (ν(C−S)) cm−1. H
NMR in acetone-d6 (δ): 9.03 (d, 1H, H3,5 pz), 8.99 (d, 2H, H3,5 pz),
8.32 (d, 1H, H3,5 pz), 7.54 - 7.24 (m, 15H, PPh3), 7.10 (d, 1H, H3,5
pz), 6.95 (d, 1H, H3,5 pz), 6.67 (d, 1H, H4 pz), 6.24 (d, 1H, H4 pz),
6.17 (d, 1H, H4 pz), 2.47 (s, 3H, CH3) ppm. 13C{1H} NMR in
acetone-d6 (δ): 147.2 (s, C-3,5 pz), 146.9 (s, C-3,5 pz), 143.5 (s, C-3,5
pz), 137.1 (s, C-3,5 pz), 137.0 (s, C-3,5 pz), 135.9 (s, C-3,5 pz), 133.6
(d, 2JCP = 9.0 Hz, PPh3), 131.9 (d, JCP = 41.0 Hz, C-1 PPh3), 130.0 (s,
PPh3), 128.3 (d, 2JCP = 9.0 Hz, PPh3), 124.0 (s, NCCH3), 107.2 (s, C-
4 pz), 106.9 (s, C-4 pz), 106.8 (s, C-4 pz), 90.9 (s, C-SO3), 4.1 (s,
NCCH3) ppm. 31P NMR in acetone-d6 (δ): 49.2 (s, PPh3) ppm.
Synthesis of [Ru(N3)(NCPh){κ3(N,N,N)-Tpms}(PPh3)] (8). Benzoni-
trile (66 μL, 0.650 mmol) was added to a solution of complex
[Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100 mg, 0.131 mmol)
in toluene (15 mL), and the reaction mixture was heated at reflux
temperature for 5 h. Solvents were removed under a vacuum, and the
yellow residue was extracted with dichloromethane. The resulting
solution was filtered through kieselguhr and concentrated under
vacuum to a volume of approximately 1 mL. Addition of hexane
afforded a yellow precipitate. Solvents were decanted and the solid was
washed with hexane (3 × 20 mL) and dried under reduced pressure.
2
pz), 135.1 (s, C-3,5 pz), 134.5 (s, NCS), 134.1 (d, JCP = 12.0 Hz,
PPh3), 133.4 (d, JCP = 41.0 Hz, C-1 PPh3), 129.2 (s, PPh3), 128.0 (d,
2JCP = 12.0 Hz, PPh3), 106.4 (s, C-4 pz), 106.2 (s, C-4 pz), 106.1 (s, C-
4 pz), 91.2 (s, C-SO3) ppm. 31P NMR in acetone-d6 (δ): 51.5 (s, PPh3)
ppm.
Synthesis of [Na][Ru{κ(N)-NCS}2{κ3(N,N,N)-Tpms}(PPh3)] (6). CS2
(790 μL, 13.1 mmol) was added to a solution of complex
[Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100 mg, 0.131
mmol) in acetone (30 mL), and the mixture was refluxed for 3.5 h.
Solvents were then removed under vacuum. Addition of diethyl ether
(30 mL) afforded a brown precipitate. Solvents were decanted and the
solid residue was washed with diethyl ether (3 × 10 mL) and dried
under reduced pressure. Yield: 80 mg (77%). Anal. Calcd. for
C30H24N8NaO3PRuS3: C, 45.28; H, 3.04; N, 14.08; S, 12.09. Found:
C, 44.71; H, 3.01; N, 13.67; S, 11.85. MS-ESI (m/z): 773 ([M]−,
100%). Molar conductivity in acetone: ΛM = 108 S cm2 mol−1. IR
(KBr): 2121 (ν(NCS)); 1275 and 1058 (ν(S−O)); 833 (ν(C−N));
1
622 (ν(C−S)) cm−1. H NMR in acetone-d6 (δ): 8.96 (dd, 2H, H3,5
pz), 8.92 (m, 1H, H3,5 pz), 8.17 (m, 1H, H3,5 pz), 7.50−7.21 (m, 15H,
PPh3), 6.64 (m, 3H, H3,5 and H4 pz), 6.10 (dd, 2H, H4 pz) ppm.
13C{1H} NMR in acetone-d6 (δ): 147.0 (s, C-3,5 pz), 144.1 (s, C-3,5
pz), 136.5 (s, C-3,5 pz), 136.0 (s, NCS), 135.2 (s, C-3,5 pz), 134.0 (d,
2JCP = 10.1 Hz, PPh3), 133.4 (d, JCP = 40.2 Hz, C-1 PPh3), 129.6 (s,
PPh3), 128.3 (d, 2JCP = 9.1 Hz, PPh3), 106.8 (s, C-4 pz), 106.4 (s, C-4
pz), 91.1 (s, C-SO3) ppm. 31P NMR in acetone-d6 (δ): 50.9 (s, PPh3)
ppm.
Synthesis of [Ru(N3)(NCMe){κ3(N,N,N)-Tpms}(PPh3)] (7). A sol-
ution of complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) (100
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Yield: 92 mg (88%). Anal. Calcd. for C35H29N10O3PRuS: C, 52.43; H,
3.65; N, 17.47; S, 4.00. Found: C, 52.35; H, 4.00; N, 17.34; S, 3.60.
MS-ESI (m/z): 825 ([M + Na]+, 49%); 721 ([M-NCPh + Na]+, 95%).
IR (KBr): 2136 (ν(NCPh)); 2038 (ν(N3)); 1284 and 1054 (ν(S−
absorption correction was applied using the SCALE3 ABSPACK
algorithm as implemented in the program CrysAlis Pro RED.15
The software package WINGX16 was used for space group
determination, structure solution, and refinement. The structure for
the complexes 2b and 7 were solved by direct methods using SIR92.17
For 9 the structure was solved by Patterson interpretation and phase
expansion using DIRDIF.18
1
O)); 802 (ν(C−N)); 621 (ν(C−S)) cm−1. H NMR in acetone-d6
(δ): 9.05 (d, 1H, H3,5 pz), 9.01 (d, 2H, H3,5 pz), 8.40 (d, 1H, H3,5 pz),
7.77 - 7.19 (m, 21H, PPh3, Ph and H3,5 pz), 7.16 (d, 1H, H3,5 pz), 7.00
(d, 1H, H4 pz), 6.30 (d, 1H, H4 pz), 6.20 (d, 1H, H4 pz) ppm.
13C{1H} NMR in acetone-d6 (δ): 148.0 (s, C-3,5 pz), 146.6 (s, C-3,5
pz), 143.5 (s, C-3,5 pz), 137.0 (s, C-3,5 pz), 135.9 (s, C-3,5 pz), 133.7
(d, 2JCP = 9.0 Hz, PPh3), 131.8 (s, Ph), 130.1 (s, PPh3), 128.9 (s, Ph),
128.4 (d, 2JCP = 9.0 Hz, PPh3), 128.1 (s, Ph), 125.2 (s, NCPh), 107.4
(s, C-4 pz), 107.1 (s, C-4 pz), 106.9 (s, C-4 pz), 90.9 (s, C-SO3) ppm.
31P NMR in acetone-d6 (δ): 48.8 (s, PPh3) ppm.
Isotropic least-squares refinement on F2 using SHELXL9719 was
performed. During the final stages of the refinements, all the positional
parameters and the anisotropic temperature factors of all the non-H
atoms were refined. The H atoms were geometrically located and their
coordinates were refined riding on their parent atoms. The function
2
2
2
minimized was ([ΣwFo − Fc2)/Σw(Fo )]1/2 where w = 1/[σ2(Fo ) +
(aP)2 + bP] (for 2b, a = 0.0732, b = 2.2361, for 7 a = 0.0689, b =
2
Synthesis of [Na][Ru{κ2(N1,N3)-N3C(H)C−CN4}{κ3(N,N,N)-Tpms}-
(PPh3)] (9). Fumaronitrile (52 mg, 0.655 mmol) was added to a
solution of complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1)
(100 mg, 0.131 mmol) in acetone (30 mL). The reaction mixture was
heated at the reflux temperature for 5 h and the resulting solution was
concentrated under vacuum to a volume of approximately 1 mL.
Addition of hexane afforded a yellow solid which was washed with
hexane (3 × 30 mL) and dried under reduced pressure. Yield: 43 mg
(40%). Anal. Calcd. for C31H25N13NaO3PRuS: C, 45.70; H, 3.09; N,
22.35; S, 3.94. Found: C, 45.64; H, 3.30; N, 22.09; S, 3.81. MS-ESI
(m/z): 792 ([M]−, 95%). Molar conductivity in acetone: ΛM = 95 S
cm2 mol−1. IR (KBr): 2055 (ν(CN)); 1624 (ν(CC)); 1298 and
1.4515 and for 9, a = 0.0382, b = 3.0240) with σ(Fo ) from counting
statistics and P = (Max (Fo , 0) + 2Fc2)/3.
2
Atomic scattering factors were taken from the International Tables
for X-ray Crystallography International.20 The crystallographic plots
were made with PLATON.21
CCDC: 905387, 905388, and 905389 contain the supplementary
crystallographic data for 2b·2C3H6O, 7·CH2Cl2, and 9·C4H10O
respectively. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
RESULTS AND DISCUSSION
■
1
1056 (ν(S−O)); 746 (ν(C−N)); 623 (ν(C−S)) cm−1. H NMR in
Synthesis of the Diazido Complex [Na][Ru(N3)2{κ3(N,N,N)-
Tpms}(PPh3)] (1). Reaction of complex [RuCl{κ3(N,N,N)-
Tpms}(PPh3)2] with an excess of sodium azide in a mixture
dichloromethane/methanol (1:3) at 65 °C leads to the anionic
complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)] (1) in 65%
yield (Scheme 1).
acetone-d6 (δ): 9.10 (d, 2H, H3,5 pz), 9.04 (d, 1H, H3,5 pz), 7.89 (s,
1H, CH), 7.59 (d, 1H, H3,5 pz), 7.53 (d, 1H, H3,5 pz), 7.34−6.59 (m,
15H, PPh3), 6.27 (d, 1H, H4 pz), 6.21 (d, 1H, H4 pz), 6.16 (m, 2H, H4
and H3,5 pz) ppm. 13C{1H} NMR in acetone-d6 (δ): 158.2 (s, N4C),
149.1 (s, C-3,5 pz), 148.6 (s, C-3,5 pz), 140.5 (s, C-3,5 pz), 136.4 (s,
C-3,5 pz), 136.3 (s, C-3,5 pz), 135.6 (s, CH-C), 135.3 (s, C-3,5 pz),
2
133.4 (d, JCP = 9.0 Hz, PPh3), 133.1 (d, JCP = 41.0 Hz, C-1 PPh3),
2
Scheme 1. Synthesis of [Na][Ru(N3)2{κ3(N,N,N)-
Tpms}(PPh3)]
129.3 (s, PPh3), 127.8 (d, JCP = 9.0 Hz, PPh3), 127.6 (s, CH), 106.5
(s, C-4 pz), 106.3 (s, C-4 pz), 106.1 (s, C-4 pz), 91.3 (s, C-SO3) ppm.
31P NMR in acetone-d6 (δ): 52.2 (s, PPh3) ppm.
Synthesis of [Na][Ru(N3){κ(N1)-N3CH(CN)CH(CN)}{κ3(N,N,N)-
Tpms}(PPh3)] (10). Fumaronitrile (52 mg, 0.655 mmol) was added
to a solution of complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}(PPh3)]
(1) (100 mg, 0.131 mmol) in acetone (60 mL) and the reaction
mixture was heated at the reflux temperature for 45 min. Then, the
solution was cooled quickly at 0 °C and concentrated at the same
temperature. The solid residue was washed with diethyl ether (3 × 30
mL) and dried under reduced pressure. Yield: 64 mg (58%). Anal.
Calcd. for C32H26N14NaO3PRuS: C, 45.66; H, 3.11; N, 23.30; S, 3.81.
Found: C, 45.66; H, 3.30; N, 23.62; S, 3.84. MS-ESI (m/z): 819
([M]−, 53%). IR (KBr): 2232 (ν(CN)); 2048 (ν(NNN) and
ν(CN)); 1277 and 1055 (ν(S−O)); 833 (ν(C−N)); 623 (ν(C−S))
Complex 1 is isolated as a yellow powder. The molar
conductivity value found for complex 1 in acetone (89 S cm2
mol−1) is lower than expected for a 1:1 electrolyte (100−140 S
cm2 mol−1).22 Complex 1 has been analytically and
spectroscopically characterized (IR and 1H, 13C{1H} and
31P{1H} NMR). In particular, the IR spectrum (KBr) shows
the characteristic absorptions for the ligand Tpms in a
κ3(N,N,N)-coordination mode:23 two medium signals at 1281
and 1055 cm−1 due to the ν(S−O) from the sulfonate moiety, a
weak band at 832 cm−1 due to the ν(C−N) of the pyrazole
rings and the absorption at 622 cm−1 assigned to the stretching
ν(C−S). Finally, the absorption due to the azide group appears
as a strong signal at 2048 cm−1.
1
cm−1. H NMR in acetone-d6 (δ): 8.99 (d, 2H, H3,5 pz), 8.79 (d, 1H,
H
3,5 pz), 7.90 - 6.96 (m, 18H, H3,5 pz and PPh3), 6.25 (d, 2H, H4 pz),
6.20 (d, 1H, H4 pz), 4.82 (d, 1H, 3JHH = 11.0 Hz, CH(CN)), 4.02 (d,
3
1H, JHH = 11.0 Hz, CH(CN)) ppm. 13C{1H} NMR in acetone-d6 at
252 K (δ): 147. Nine (s, C-3,5 pz), 147.7 (s, C-3,5 pz), 141.1 (s, C-3,5
2
pz), 140.6 (s, C-3,5 pz), 133.7 (d, JCP = 9.0 Hz, PPh3), 129.2 (s,
2
PPh3), 128.0 (d, JCP = 9.0 Hz, PPh3), 120.6 (s, CN), 119.8 (s, CN),
106.7 (s, C-4 pz), 106.4 (s, C-4 pz), 91.0 (s, C-SO3), 66.1 (s,
CH(CN)), 60.0 (s, CH(CN)) ppm. 31P NMR in acetone-d6 (δ): 54.3
(s, PPh3) ppm.
X-ray Crystal Structure Determination of Complexes
2b·2C3H6O, 7·CH2Cl2, and 9·C4H10O. The most relevant crystal
and refinement data are collected in Table 1.
31P{1H} spectrum exhibits a singlet at 52.5 ppm due to the
1
PPh3 phosphorus atom. H and 13C{1H} NMR spectra agree
In all cases, diffraction data were recorded on a Oxford Diffraction
Xcalibur Nova single crystal diffractometer, using Cu−Kα radiation (λ
= 1.5418 Å). Images were collected at a 63 mm fixed crystal-detector
distance, using the oscillation method, with 1° oscillation and variable
exposure time per image (2−10), (15−55), and (6−20) s for 2b, 7,
and 9 respectively. Data collection strategy was calculated with the
program CrysAlis Pro CCD.15 Data reduction and cell refinement
were performed with the program CrysAlis Pro RED.15 An empirical
with the proposed structure (see Experimental Section).
The presence of two azide ligands is evidenced by the
electrospray mass spectrum measured in a negative mode for
complex 1 that shows a peak at m/z 741 for the anion
[Ru(N3)2(Tpms)(PPh3)]¯ .
Cycloaddition Reactions with the Alkynes DMAD and
DEAD. Synthesis of the Complexes [Na][Ru{κ(N2)-
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N3C2(CO2R)2}2{κ3(N,N,N)-Tpms}(PPh3)] (R = Me (2a), Et (2b)).
The reaction of complex 1 with an excess of dimethyl
acetylenedicarboxylate (DMAD) or diethyl acetylenedicarbox-
ylate (DEAD) in acetone at room temperature leads to the
N(2)-bound 4,5-bis(alkoxycarbonyl)-1,2,3-triazolato complexes
[Na][Ru{κ(N2)-N3C2(CO2R)2}2{κ3(N,N,N)-Tpms}(PPh3)]
(R = Me (2a), Et (2b)) (Scheme 2), generated by the 1,3-
dipolar cycloaddition of the two azido groups with two
molecules of the alkyne.
Scheme 2. Synthesis of Complexes [Na][Ru{κ(N2)-
N3C2(CO2R)2}2{κ3(N,N,N)-Tpms}(PPh3)]
Figure 1. Perspective view of the anion of 2b·2C3H6O with atom
numbering scheme showing 10% probability thermal ellipsoids.
Solvent molecules, hydrogen atoms, phenyl rings, and sodium atoms
have been omitted for clarity. Selected bond lengths (Å): Ru(1)−N(1)
= 2.093(2), Ru(1)−N(3) = 2.100(2), Ru(1)−N(5) = 2.095(2),
Ru(1)−P(1) = 2.341(1), Ru(1)−N(8) = 2.082(2), Ru(1)−N(11) =
2.075(2), N(7)−N(8) = 1.331(3), N(8)−N(9) = 1.337(3), N(11)−
N(12) = 1.331(3), N(10)−N(11) = 1.334(3). Selected bond angles
(°): N(1)−Ru(1)−N(3) = 83.36(9), N(3)−Ru(1)−N(5) = 82.64(9),
N(5)−Ru(1)−N(1) = 85.48(9), N(8)−Ru(1)−N(11) = 93.90(9),
N(8)−Ru(1)−P(1) = 87.46(7), N(11)−Ru(1)−P(1) = 94.11(7).
The formation of these complexes was readily confirmed by
the disappearance of the characteristic azide IR absorption and
the appearance of the CN stretching bands at 2071 (2a) and
2077 (2b) cm−1 as well as the CO stretching bands from the
carbonyl groups at 1732 (2a) and 1725 (2b) cm−1.
The NMR spectroscopic data agree with the proposed
stoichiometries. The more remarkable features are as follows:
1
(i) H NMR spectra show a singlet for the four methyl groups
at 3.79 ppm for complex 2a and one triplet (1.28 ppm, 3JHH = 7
3
Hz) and one cuatriplet (4.26 ppm, JHH = 7 Hz) for the four
those found for other ruthenium(II) Tpms complexes.14 The
distances from the ruthenium atom to the triazolate rings
Ru(1)−N(8) and Ru(1)−N(11) are 2.082(2) and 2.075(2) in
accordance with those found for [Ru{N3C2H(CO2Me)}(η5-
C5H5)(dppe)] (2,090(2) Å).13
An important feature of this crystal structure is that the
complex in the solid state consists of linear chains generated by
the crystal periodicity along the a axis. These chains are
produced by electrostatic interactions between the anionic
complexes and the sodium atoms which are located in the front
leading to a tubular structure (Figure 2).
Thus, three ruthenium complexes surround each sodium
atom leading to a heptacoordinate environment provided by
two oxygen atoms from two carboxylic groups of one anionic
moiety, two oxygen atoms and two nitrogen atoms from two
triazolate groups of a second one and an oxygen atom from the
sulfonate group of a third unit (Figure 3).
The existence of these ionic associations can explain the low
values for the molar conductivity found for complexes 2a,b.
For complexes 2a−b, only the N(2)-bound triazolate ligand
has been observed. However, initial formation of the complex
containing the N(1)-bound triazolate ligand and subsequent
conversion to the thermodynamically more stable N(2)-bound
isomer cannot be excluded, in agreement with previously
reported data.10b,13
ethyl groups in complex 2b, indicating that the two rings are
bound through the N(2) atom for these complexes; (ii) the
31P{1H} spectra exhibit a singlet at 51.8 (2a) and 51.9 (2b)
ppm according to the presence of the PPh3 ligand; (iii) the
signals on the 13C{1H} NMR spectra have been fully assigned
through HSQC and HMBC experiments and agree with the
proposed complexes. Thus, for the N(2)-bound triazolate
groups, the spectra show a singlet signal for the equivalent
heterocyclic carbons at 139.3 (2a) and 139.5 (2b) ppm and for
the carbonyl atoms at 163.0 (2a) and 162.8 (2b) ppm.
For both complexes the electrospray mass spectra show the
c o r r e s p o n d i n g p e a k a t m / z 1 0 2 5 f o r [ R u -
{N3C2(CO2Me)2}2(Tpms)(PPh3)]¯ (2a) and at m/z 1081 for
[Ru{N3C2(CO2Et)2}2(Tpms)(PPh3)]¯ (2b).
The molar conductivity values found for complexes 2a,b in
acetone (92 (2a) and 81 (2b) S cm2 mol−1) are lower than
expected for a 1:1 electrolyte (100−140 S cm2 mol−1).22 These
low values can be attributed to ionic associations between the
sodium cations and the anionic moieties.
Slow evaporation of a concentrated solution of complex 2b
in acetone resulted in crystals of 2b·2 C3H6O suitable for X-ray
diffraction studies. A thermal ellipsoid plot is shown in Figure 1,
and selected bond lengths and angles are presented in the
caption.
Attempts to obtain the free organic triazoles were
accomplished. The treatment of complex 2a with benzyl
bromide, in acetone, at 60 °C for 24 h, causes the cleavage of
the Ru−N bond as observed by NMR spectroscopy. Thus,
31P{1H} spectrum shows the disappearance of the signal at 51.8
ppm, while a new signal at 47.8 ppm appears. Moreover, the
The ruthenium atom exhibits a distorted octahedral
coordination geometry bonded κ3(N,N,N) to the Tpms ligand,
to the phosphorus atom of the PPh3 and to the N(2) of the two
planar five-membered triazolate rings. For the Tpms ligand, the
interligand N−Ru−N angles (82.64−85.48°) and the Ru−N
bond distances (2.093(2)−2.100(2) Å) are in the range of
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Figure 2. Tubular chain structure for complex [Na][Ru{κ(N2)-N3C2(CO2Et)2}2{κ3(N,N,N)-Tpms}(PPh3)]·2C3H6O (2b·2C3H6O).
Scheme 3. Synthesis of complexes
[Na][Ru(N3){N3C2H(CO2Me)}{κ3(N,N,N)-Tpms}(PPh3)]
(3) and [Na][Ru{N3C2H(CO2Me)}2{κ3(N,N,N)-
Tpms}(PPh3)] (4)
Figure 3. Sodium coordination sphere in the structure of complex
[Na][Ru{κ(N2)-N3C2(CO2Et)2}2{κ3(N,N,N)-Tpms}(PPh3)]·2C3H6O
(2b·2C3H6O).
1
ppm (3) and 7.82 and 3.77 ppm (4), respectively, in the H
NMR spectra.
1
signals for the organic triazole can be identified in H NMR
spectrum of the crude product.12 Unfortunately, all the
attempts to isolate the free organic triazole were unsuccessful.
Cycloaddition Reactions with Methyl Propiolate.
Synthesis of the Complexes [Na][Ru(N3){N3C2H(CO2Me)}-
{κ3(N,N,N)-Tpms}(PPh3)] (3) and [Na][Ru{N3C2H-
(CO2Me)}2{κ3(N,N,N)-Tpms}(PPh3)] (4). The reaction of com-
plex 1 with an excess of methyl propiolate in acetone at room
temperature for 15 h affords the complex [Na][Ru(N3)-
{N3C2H(CO2Me)}{κ3(N,N,N)-Tpms}(PPh3)] (3) resulting in
the cycloaddition of one azido group with the carbon−carbon
triple bond of the alkyne. When this reaction is carried out in
refluxing acetone, the complex with two triazolate rings
[Na][Ru{N3C2H(CO2Me)}2{κ3(N,N,N)-Tpms}(PPh3)] (4) is
obtained (Scheme 3).
The electrospray mass spectrum of complex 3 shows peaks at
m/z 825 for the anion [Ru(N3){N3C2H(CO2Me)}(Tpms)-
(PPh3)]¯ and m/z 563 for the anion [Ru(N3){N3C2H-
(CO2Me)}(Tpms)]¯.
Even when the spectroscopic data do not allow one to
establish the coordination mode of the triazolate ligands, the
coordination through the N(2) is proposed in agreement with
the isomer obtained for complexes 2a,b and the structure of the
previously reported complex [Ru{N3C2H(CO2Me)}(η5-C5H5)-
(dppe)].13
Reaction with Carbon Disulfide. Synthesis of [Na][Ru-
(N3){κ(N)-NCS}{κ3(N,N,N)-Tpms}(PPh3)] (5) and [Na][Ru{κ(N)-
NCS}2{κ3(N,N,N)-Tpms}(PPh3)] (6). Complex 1 also reacts with
CS2 in refluxing acetone to give the isothiocyanato complexes
[Na][Ru(N3){κ(N)-NCS}{κ3(N,N,N)-Tpms}(PPh3)] (5) and
[Na][Ru{κ(N)-NCS}2{κ3(N,N,N)-Tpms}(PPh3)] (6) depend-
ing on the amount of excess CS2 used. Both complexes have
been characterized by analytical and spectroscopic methods.
Significant spectroscopic data are given: (i) the stretching
frecuency of the NCS group (2117 cm−1 for complex 5 and
2121 cm−1 for complex 6) and the peak corresponding to the
terminal azide group for complex 5 (2060 cm−1) appear in the
IR spectra (KBr), together with the typical absorptions for the
κ3(N,N,N)-Tpms ligand; (ii) the 31P{1H} NMR spectra show
Complexes 3 and 4 are stable yellow solids and have been
characterized by analytical and spectroscopic methods. The IR
spectra for both complexes show the corresponding absorptions
for the Tpms and triazolate ligands. IR spectrum of complex 3
also shows a strong band at 2052 cm−1 due to the azide ligand.
The 31P{1H} NMR spectra exhibit singlet resonances at 52.5
1
and 51.5 ppm for complexes 3 and 4, respectively. H and
13C{1H} NMR spectra agree with the proposed structure (see
Experimental Section). In particular, the proton for the CH and
the methyl groups of triazolate rings appear at 7.87 and 3.81
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the signal for the phosphorus atom of the PPh3 ligand at 51.5
(5) and 50.9 (6) ppm; (iii) 13C{1H} NMR spectra show the
signal corresponding to the NCS group at 134.5 (5) and 136.0
1
(6) ppm. The rest of signals as well as the H NMR spectra
agree with the proposed structures (see Experimental Section).
Molar conductivity values in acetone (113 S cm2 mol−1 for 5
and 108 S cm2 mol−1 for 6) are in the range expected for
electrolytes 1:1 and the electrospray mass spectra show the
peak at m/z 757 for [Ru(N3)(NCS)(Tpms)(PPh3)]¯ (5) and
773 for [Ru(NCS)2(Tpms)(PPh3)]¯ (6).
The formation of complexes 5 and 6 from complex 1 and
CS2 is a well-known transformation24 and can be explained
through a [3 + 2] cycloaddition reaction of CS2 with azido
groups yielding thiothiazolinate intermediates which are
thermally unstable and decompose, in the reaction conditions,
leading to the obtained isothiocyanato complexes.25
Reaction with Nitriles. Synthesis of the Complexes
[Ru(N3)(NCR){κ3(N,N,N)-Tpms}(PPh3)] (R = Me (7), Ph (8)).
Heating an acetonitrile solution of complex 1 at reflux
temperature leads to the substitution product [Ru(N3)-
(NCMe){κ3(N,N,N)-Tpms}(PPh3)] (7). In the same way,
when complex 1 was refluxed with an excess of PhCN in
toluene, the analogous [Ru(N3)(NCPh){κ3(N,N,N)-Tpms}-
(PPh3)] (8) was obtained. Both complexes have been
analytically and spectroscopically characterized. Significant
spectroscopic data are given: (i) the IR spectra (KBr) exhibit
the absorptions corresponding to the ν(CN) at 2131 (7) and
2136 (8) cm−1, and the absorptions due to the azido ligands at
2036 (7) and 2038 (8) cm−1; ii) the 31P{1H} NMR spectra
show singlet signals at 49.2 (7) and 48.8 (8) ppm; (iii) the
13C{1H} NMR spectra show the signal for the CN carbon at
Figure 4. Molecular structure and atom-labeling scheme for the
complex [Ru(N3)(NCMe){κ3(N,N,N)-Tpms}(PPh3)]·CH2Cl2. Hy-
drogen atoms and solvent molecules have been omitted for clarity.
Non-hydrogen atoms are represented by 20% probability ellipsoids.
Selected bond lengths (Å): Ru(1)−N(1) = 2.105(3), Ru(1)−N(3) =
2.069(3), Ru(1)−N(5) = 2.044(3), Ru(1)−P(1) = 2.330(1), Ru(1)−
N(7) = 2.120(3), Ru(1)−N(10) = 2.018(4), N(7)−N(8) = 1.207(5),
N(8)−N(9) = 1.153(5), N(10)−C(29) = 1.154(9), C(29)−C(30) =
1.448(6). Selected bond angles (°): N(1)−Ru(1)−N(3) = 82.15(13),
N(3)−Ru(1)−N(5) = 87.81(13), N(5)−Ru(1)−N(1) = 84.47(13),
N(7)−Ru(1)−P(1) = 93.99(10), N(10)−Ru(1)−P(1) = 92.70(11),
N(10)−Ru(1)−N(7) = 86.35(15), Ru(1)−N(7)−N(8) = 120.50(3),
N(7)−N(8)−N(9) = 177.10(4), Ru(1)−N(10)−C(29) = 174.20(3),
N(10)−C(29)−C(30) = 177.30(5).
1
124.0 (7) and 125.2 (8) ppm; (iv) the H and 13C{1H} NMR
spectra of complex 7 show singlet signals for the methyl group
of the nitrile at 2.47 ppm (1H) and 4.1 ppm (13C).
The structure of complex 7 was determined by single crystal
X-ray diffraction analysis. Slow evaporation of a dichloro-
methane solution of complex 7 enables one to obtain crystals
suitable for X-ray diffraction studies of 7·CH2Cl2. A thermal
ellipsoid plot of the complex is shown in Figure 4, and selected
bond lengths and angles are presented in the caption.
The ruthenium atom exhibits a distorted octahedral
coordination geometry bonded κ3(N,N,N) to the Tpms ligand,
to the nitrogen atoms of azido and acetonitrile groups and the
phosphorus atom of the PPh3 ligand. The Ru−N bond length
trans to the phosphane ligand is significantly longer than those
trans to the acetonitrile and azido groups, in accordance with
the higher trans influence for the phosphane ligands.26
The acetonitrile and the azido groups display a linear (Ru−
N−C, 174.20°) and angular (Ru−N−N, 120.50°) arrangement
respectively, in accordance with the different hybridization of
the nitrogen in both ligands. The Ru−N(7) and Ru−N(10)
bond distances are in agreement with the data found for other
ruthenium complexes containing azido12 and nitrile27 groups
respectively.
Reaction with Fumaronitrile. Synthesis of [Na][Ru-
{κ2(N1,N3)-N3C(H)C−CN4}{κ3(N,N,N)-Tpms}(PPh3)] (9) and
[Na][Ru(N3){N4C(CHCH(CN)}{κ3(N,N,N)-Tpms}(PPh3)] (10).
The reaction of complex 1 with an excess of fumaronitrile in
refluxing acetone affords a new complex [Na][Ru{κ2(N1,N3)-
N3C(H)C−CN4}{κ3(N,N,N)-Tpms}(PPh3)] (9), which con-
tains a bidentate ligand 5-(1,2,3-triazol-4-yl)-1,2,3,4-tetrazo-
late28 coordinated through the N(1) of the tetrazole ring and
the N(3) of the triazole ring (Scheme 4). This complex 9 is the
result of the cycloaddition reaction of the two azide groups with
the CN and CC bonds of fumaronitrile.
Scheme 4. Synthesis of Complex [Na][Ru{κ2(N1,N3)-
N3C(H)C−CN4}{κ3(N,N,N)-Tpms}(PPh3)] (9)
The stoichiometry of this complex was confirmed through
elemental analyses and electrospray mass spectrum which
shows the peak at m/z 792 for the anion [Ru{N3C(H)C−
CN4}(Tpms)(PPh3)]¯.
Complex 9 has been also spectroscopically characterized (IR
1
and H, 13C{1H} and 31P{1H} NMR). In particular, the IR
spectrum (KBr) shows the characteristic absorptions for the
ligand Tpms in a κ3(N,N,N)-coordination mode and the
absorptions due to the CN bonds. The reaction through the
two azide groups is also confirmed by the disappearance of the
terminal azide peak.
1H and 13C{1H} NMR spectra agree with the proposed
structure. Thus, for the triazolate ring the proton appears as a
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singlet at 7.89 ppm and the carbon atoms at 135.6 (cuaternary
carbon) and 127.6 (CH) ppm and for the tetrazolate ring the
carbon atom appears at 158.2 ppm.
Slow diffusion of diethyl ether into a solution of 9 in acetone
resulted in crystals of 9·C4H10O suitable for a single crystal X-
ray diffraction studies. A thermal ellipsoid plot of the anion of
the complex is shown in Figure 5, and selected bond lengths
and angles are presented in the caption.
The torsion angle N(8)−C(13)−C(14)−N(11) (2.4(4)°)
agrees with the planarity of the two rings.
In the solid state, complex 9 shows periodicity along the a
and c axis leading to a layer structure (Figure 6). These layers
Figure 6. Layer structure in complex [Na][Ru{κ2(N1,N3)-N3C(H)C−
CN4}{κ3(N,N,N)-Tpms}(PPh3)]·C4H10O (9·C4H10O).
are generated by electrostatic interactions between the anionic
complexes and the sodium atoms which show a tetracoordi-
nated environment provided by an oxygen atom of the
sulfonate group of an anionic unit, two nitrogen atoms of a
second and third anionic units and the oxygen atom of a diethyl
ether molecule (Figure 7).
The cycloaddition reaction of fumaronitrile with azides can
take place via either the CC or the CN bond. In our case,
the unprecedented formation of complex 9 can be explained as
the result of two consecutive cycloaddition reactions, and
therefore three different pathways can be proposed according
to the literature data (Scheme 5).
Figure 5. Perspective view of the anion of complex 9·C4H10O with
atom numbering scheme showing 10% probability thermal ellipsoids.
Solvent molecules, hydrogen atoms, and sodium atoms have been
omitted for clarity. Selected bond lengths (Å): Ru(1)−N(1) =
2.058(2), Ru(1)−N(3) = 2.096(2), Ru(1)−N(5) = 2.054(2), Ru(1)−
P(1) = 2.314(1), Ru(1)−N(8) = 2.070(2), Ru(1)−N(14) = 2.070(2),
N(8)−N(9) = 1.329(3), N(8)−C(13) = 1.359(3), N(9)−N(10) =
1.333(4), N(10)−C(12) = 1.353(4), C(12)−C(13) = 1.355(4),
C(13)−C(14) = 1.443(4), N(13)−N(14) = 1.327(3), N(14)−C(14)
= 1.347(3), N(12)−N(13) = 1.323(3), N(12)−N(11) = 1.361(4),
N(11)−C(14) = 1.336(4). Selected bond angles (°): N(1)−Ru(1)−
N(3) = 84.17(9), N(3)−Ru(1)−N(5) = 82.74(9), N(5)−Ru(1)−
N(1) = 87.20(8), N(8)−Ru(1)−N(14) = 77.18(9), N(8)−Ru(1)−
P(1) = 92.75(7), N(14)−Ru(1)−P(1) = 94.19(7), N(8)−N(9)−
N(10) = 108.0(2), N(9)−N(8)−C(13) = 108.7(2), N(10)−C(12)−
C(13) = 106.8(3), C(12)−C(13)−C(14) = 138.3(3), N(8)−C(13)−
C(14) = 114.3(2), C(13)−C(14)−N(14) = 115.4(2), C(14)−
N(14)−N(13) = 107.4(2), N(11)−C(14)−C(13) = 134.8(3).
In the Via 1, the process would be initiated by the
cycloaddition of one azide group and one nitrile group of
fumaronitrile, to give the tetrazolato intermediate I. The
intramolecular [3 +2] cycloaddition between the second azide
ligand and the CC double bond following removal of a HCN
molecule would form the final product. Intermediate I is
proposed as the N(1) bound isomer, since this isomer is
proposed to be the kinetically more stable isomer for tetrazolate
complexes.29 Thermodinamically stable N(2)-bound cyanovi-
nyltetrazolate complexes have been described in the reaction of
fumaronitrile with azido complexes of Mo,9 In,30 and Mn.31
The first step of Vias 2 and 3 would involve the [3 +2]
cycloaddition of one azide ligand with the CC double bond.
For Via 2, HCN elimination occurs in this first step, leading to
the 4-cyano-1,2,3-triazolato complex (intermediate II). Intra-
molecular cycloaddition reaction between the second azide
ligand and the CN bond leads to the observed complex 9.
This mechanism agrees with the reported reactions of
ruthenium complexes with fumaronitrile in which complexes
containing a N(2)-bound 4-cyano-1,2,3-triazolate ligand have
been isolated.11−13
The ruthenium atom exhibits a distorted octahedral
coordination geometry bonded κ3(N,N,N) to the Tpms ligand,
to the phosphorus atom of the PPh3 and to two nitrogen atoms
of the bidentate κ2(N1,N3)-5-(1,2,3-triazol-4-yl)-1,2,3,4-tetrazo-
late ligand.
For the Tpms ligand, the interligand N−Ru−N angles
(82.74−87.20°) and the Ru−N bond distances (2.054(2) −
2.096(2) Å) agree with those found for other ruthenium(II)
Tpms complexes.14 The distances from the ruthenium atom to
the triazolate ring Ru(1)−N(8) (2.070(2) Å) and to the
tetrazolate ring Ru(1)−N(14) (2.070(2) Å) are in the range of
those described for complex 2a (2.082(2) and 2.075(2) Å).
For Via 3, the [3 +2] cycloaddition of one azide ligand with
the CC double bond leads to a triazolinato complex III.
Removal of a HCN molecule and intramolecular [3 + 2]
cycloaddition between the azide ligand, and the remaining CN
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Figure 7. Sodium coordination sphere in the structure of complex [Na][Ru{κ2(N1,N3)-N3C(H)C−CN4}{κ3(N,N,N)-Tpms}(PPh3)]·C4H10O
(9·C4H10O).
Via 3 can be assumed as the mechanistic route for the
formation of complex 9.
Scheme 5. Mechanistic Routes for the Formation of
Complex 9
Complex 10 is isolated as a yellow stable solid and has been
1
analytically and spectroscopically characterized (IR and H,
13C{1H} and 31P{1H} NMR). In particular, it must be noted
that (i) the IR spectrum (KBr) exhibits absorptions
corresponding to the Tpms ligand coordinated κ3(N,N,N) as
well as the absorption corresponding to the CN triple bond
(2232 cm−1). This spectrum also shows a strong band at 2048
cm−1 due to the azide ligand; (ii) 31P{1H} spectrum exhibits the
expected singlet corresponding to the PPh3 ligand at 54.3 ppm;
(iii) the 1H NMR spectrum shows the triazolinato ligand bound
through the N(1). Thus, the CH(CN) protons are unequiv-
alent and appear as two doublets (3JHH = 11.0 Hz.) at 4.82 and
4.02 ppm indicating, unambiguously, that the heterocycle is
N(1)-bound; (iv) 13C{1H} NMR spectrum was measured at
252 K and agrees with the proposed structure. Thus, the two
CH(CN) carbon atoms appear at 66.1 and 60.0 ppm and the
CN carbon atoms at 119.8 and 120.6 ppm.
For complex 10, the electrospray mass spectrum shows the
corresponding peak at m/z 819 for [Ru(N3){N3CH(CN)CH-
(CN)}(Tpms)(PPh3)]¯.
Triazolinate complexes are thermally unstable and to our
knowledge, complex 10 is the first triazolinate ruthenium
complex isolated and fully spectroscopically characterized.
group would allow the final product. Unstable triazolinato
complexes have been claimed to form in reaction of azido
complexes of Pd,25 Ni,32 and Co33 with olefins.
In order to get insight into the reaction mechanism for our
system, the reaction of 1 with fumaronitrile was monitorized by
31P{1H} NMR. The formation of a transient species is assessed
by the 31P{1H} NMR spectrum of the reaction mixture, which
shows, after 45 min in refluxing acetone, a singlet resonance (δ
= 54.3 ppm). The reaction mixture was then drastically cooled
to 0 °C, and the N(1)-bound 4,5-dicyano-1,2,3,-triazolinate
complex [Na][Ru(N3){N3CH(CN)CH(CN)}{κ3(N,N,N)-
Tpms}(PPh3)] (10), intermediate III, was isolated (Scheme
6). Complex 10 is unstable in solution at room temperature
and evolves readily to complex 9. On the basis of this finding,
CONCLUSIONS
■
The diazido complex [Na][Ru(N3)2{κ3(N,N,N)-Tpms}-
(PPh3)] (1) reacts with dipolarophiles such alkynes or nitriles
in 1,3-dipolar cycloaddition reactions. Depending on the alkyne
and the reaction conditions, the cycloaddition reactions can
occur through one or the two azido groups leading to
ruthenium with triazolate ligands coordinated through the
N(2). The reaction of complex 1 with nitriles such as NCMe or
PhCN leads to complexes [Ru(N3)(NCR){κ3(N,N,N)-Tpms}-
(PPh3)] in which one azide group has been substituted by the
nitrile. However, when fumaronitrile is used, a complex
containing a new bidentate ligand 5-(1,2,3-triazol-4-yl)-
1,2,3,4-tetrazole coordinated through the N(1) of the tetrazole
ring and the N(3) of the triazole ring is isolated. The formation
of this new ligand is the result of two consecutive 1,3-dipolar
cycloaddition reactions, and the mechanism for this trans-
formation has been unambiguously established through the
isolation of the intermediate complex [Na][Ru(N3){N3CH-
(CN)CH(CN)}{κ3(N,N,N)-Tpms}(PPh3)] resulting from a
first cycloaddition between a coordinated azide and the olefine
group of fumaronitrile.
Scheme 6. Synthesis of
[Na][Ru(N3){N3CH(CN)CH(CN)}{κ3(N,N,N)-
Tpms}(PPh3)] (10)
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(11) Singh, K. S.; Kreisel, K. A.; Yap, G. P. A.; Mohan Rao, K. J.
Organomet. Chem. 2006, 691, 3509−3518.
ASSOCIATED CONTENT
■
S
* Supporting Information
(12) Chen, C.-K.; Tong, H.-C.; Chen Hsu, C.-Y.; Lee, C.-Y.; Fong, Y.
H.; Chuang, Y.-S.; Lo, Y-H; Lin, Y.-C.; Wang, Y. Organometallics 2009,
28, 3358−3368.
X-ray crystallographic data of 2b·2C3H6O, 7·CH2Cl2, and
9·C4H10O in CIF format. This material is available free of
charge via the Internet at http://pubs.acs.org.
(13) Chang, C.-W.; Lee, G.-H. Organometallics 2003, 22, 3107−3116.
(14) Miguel, S.; Díez, J.; Gamasa, M. P.; Lastra, M. E. Eur. J. Inorg.
Chem. 2011, 4745−4755.
AUTHOR INFORMATION
(15) CrysAlisPro CCD, CrysAlisPro RED; Oxford Diffraction Ltd.:
Abingdon, Oxfordshire, UK, 2008.
■
Corresponding Author
*Fax: 34 985103446. E-mail: elb@uniovi.es.
(16) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837−838.
(17) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27,
435−436.
Notes
The authors declare no competing financial interest.
(18) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
García-Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykalla, C. The
DIRDIF Program System; Technical Report of the Crystallographic
Laboratory; University of Nijmegen: Nijmegen, The Netherlands,
1999.
ACKNOWLEDGMENTS
■
This work was supported by the Spanish Ministerio de
Educacio
n y Ciencia (CTQ-2010-17005 and CTQ-2011-
26481) and Consolider Ingenio 2010 (CSD2007-00006). S.
(19) Sheldrick, G. M. SHELXL97: Program for the Refinement of
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Martinez de Salinas thanks the Spanish Ministerio de
Educacion, Cultura y Deporte for a scholarship.
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