Base-induced dehydrogenation of ruthenium hydrazine complexes

Article abstract of DOI:10.1021/ic302449n

Treatment of [RuCl(PP₃^iPr)]⁺Cl^- (PP₃^iPr = P(CH₂CH₂P ⁱPr₂)₃) with hydrazine, phenylhydrazine, and methylhydrazine afforded side-on bound hydrazine complexes [RuCl(η ²-H₂N-NH₂)(η³-PP ₃^iPr)]⁺, [RuCl(η²-H ₂N-NHPh)(η³-PP₃^iPr)] ⁺, and [RuCl(η²-H₂N-NHMe) (η³-PP₃^iPr)]⁺. The analogous reactions of [RuCl₂(PP₃^Ph)] (PP ₃^Ph = P(CH₂CH₂PPh₂) ₃) with hydrazine, phenylhydrazine, and methylhydrazine afforded end-on bound hydrazine complexes [RuCl(η¹-H₂N-NH ₂)(PP₃^Ph)]⁺, [RuCl(η ¹-H₂N-NHPh)(PP₃^Ph)]⁺, and [RuCl(η¹-H₂N-NHMe)(PP₃^Ph)] ⁺. Treatment of parent hydrazine complex [RuCl(N₂H ₄)(PP₃^iPr)]⁺ with strong base afforded the dinitrogen and dihydride complexes [Ru(N₂)(PP ₃^iPr)] and [RuH₂(PP₃ ^iPr)]. Treatment of phenylhydrazine complex [RuCl(NH ₂NHPh)(PP₃^iPr)]⁺ with strong base afforded the hydrido ruthenaindazole complex [RuH(η²-NHi? - ?NC₆H₄)(η³-PP₃^iPr)] while similar treatment of methylhydrazine complex [RuCl(NH₂NHMe) (PP₃^iPr)]⁺ afforded the hydrido methylenehydrazide complex [RuH(NHNi? - ?CH₂)(PP ₃^iPr)]. Treatment of the hydrazine complexes [RuCl(NH ₂NHR)(PP₃^Ph)]⁺ (R = H, Ph, Me) with strong base afforded the dinitrogen complex [Ru(N₂)(PP ₃^Ph)].

Full text of DOI:10.1021/ic302449n

Article
pubs.acs.org/IC
Base-Induced Dehydrogenation of Ruthenium Hydrazine Complexes
Leslie D. Field,*,† Hsiu L. Li,† Scott J. Dalgarno,‡ and Ruaraidh D. McIntosh‡
†School of Chemistry, University of New South Wales, NSW 2052, Australia
‡School of EPS-Chemistry, Heriot-Watt University, Edinburgh, Scotland, UK EH14 4AS
S
* Supporting Information
iPr
ABSTRACT: Treatment of [RuCl(PP3iPr)]+Cl− (PP3
=
P(CH2CH2PiPr2)3) with hydrazine, phenylhydrazine, and
methylhydrazine afforded side-on bound hydrazine complexes
[RuCl(η2-H2N-NH2)(η3-PP3iPr)]+, [RuCl(η2-H2N-NHPh)(η3-
PP3iPr)]+, and [RuCl(η2-H2N-NHMe)(η3-PP3iPr)]+. The anal-
ogous reactions of [RuCl2(PP3Ph)] (PP3
= P-
Ph
(CH2CH2PPh2)3) with hydrazine, phenylhydrazine, and
methylhydrazine afforded end-on bound hydrazine complexes
[RuCl(η1-H2N-NH2)(PP3Ph)]+, [RuCl(η1-H2N-NHPh)-
(PP3Ph)]+, and [RuCl(η1-H2N-NHMe)(PP3Ph)]+. Treatment
of parent hydrazine complex [RuCl(N2H4)(PP3 iPr)]+ with
strong base afforded the dinitrogen and dihydride complexes [Ru(N2)(PP3 iPr)] and [RuH2(PP3iPr)]. Treatment of
phenylhydrazine complex [RuCl(NH2NHPh)(PP3iPr)]+ with strong base afforded the hydrido ruthenaindazole complex
[RuH(η2-NHNC6H4)(η3-PP3iPr)] while similar treatment of methylhydrazine complex [RuCl(NH2NHMe)(PP3iPr)]+ afforded
the hydrido methylenehydrazide complex [RuH(NHNCH2)(PP3iPr)]. Treatment of the hydrazine complexes [RuCl-
(NH2NHR)(PP3Ph)]+ (R = H, Ph, Me) with strong base afforded the dinitrogen complex [Ru(N2)(PP3Ph)].
complexes due to ligand constraints and sterics. The
tetradentate phosphine (PP3) podand ligands have previously
been utilized to bind four sites in an octahedral system leaving
the remaining two sites geometry-constrained to a cis
arrangement10 and, where the central atom has been replaced
by boron or silicon, to induce electronic effects in the resulting
complexes.11 We now report the synthesis of ruthenium
hydrazine, methylhydrazine, and phenylhydrazine complexes
containing PP3 ligands and their reactions with base.
INTRODUCTION
■
Iron-bound hydrazine, diazene, and hydrido species have been
shown to be important intermediates in the reduction of
dinitrogen at iron by the enzyme nitrogenase.1 There has been
recent interest in the synthesis of iron hydrazine and diazene
complexes as well as studies into their interconversions as
possible models of the interaction at nitrogenase.2 There has
also been interest in the synthesis of phenyl- and methyl-
substituted hydrazine and diazene complexes of iron as well as
ruthenium3−5 since these are considered more stable analogues
of the parent unsubstituted species and may be able to shed
light on the chemistry and properties of metal hydrazines and
diazenes.
RESULTS AND DISCUSSION
■
iPr
Ru Hydrazine Complexes with the PP3 Ligand.
Treatment of [RuCl(PP3iPr)]+Cl− (PP3
= tris[2-
iPr
Hydrazine (NH2NH2) can bind to a metal center in three
ways, end-on, bridging, or side-on. Similar bonding modes are
known for substituted hydrazines although end-on bound
species can be coordinated via the NH2 terminus or the
substituted NHR end.6 Substituted diazenes can also bind end-
on, bridging, or side-on in a variety of modes (Figure 1).7
We have previously reported the base-mediated conversion
of iron-bound hydrazine to diazene then to dinitrogen in the
presence of a strong base.8 More recently we reported the base-
induced conversion of coordinated hydrazine to side-on bound
diazene on ruthenium9 as well as the conversion of coordinated
phenylhydrazine to side-on bound phenyldiazene (on iron and
ruthenium) and conversion of coordinated methylhydrazine to
side-on bound methyldiazene (on ruthenium), respectively.7
In these reports, the complexes contained bidentate
phosphines as coligands and changes to these coligands were
expected to confer changes in reactivity of the resultant
(diisopropylphosphino)ethyl]phosphine) with hydrazine in
tetrahydrofuran (THF) and methanol afforded the complex
[RuCl(η2-N2H4)(η3-PP3iPr)]+Cl− (1) where the hydrazine
ligand is bound side-on and the polydentate has one pendant
arm that is not coordinated (Scheme 1). The 31P{1H} NMR
spectrum of 1 exhibits resonances at δ 108.3, 91.6, and 8.3 in a
ratio of 1:2:1 assigned to the central phosphine PC, the two
equivalent terminal phosphines PT, and the free (uncoordi-
nated) phosphine arm PF, respectively. The resonance for PF is
close to the resonance for the phosphine arms of the free ligand
(δ −15.4)12 while the resonance for PC is at higher field than in
complexes where all phosphines are coordinated (typically δ
142−162).12 The 31P solid state NMR spectrum shows similar
Received: November 8, 2012
Published: January 22, 2013
© 2013 American Chemical Society
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to the symmetry of the complex and the fact that it is part of an
AA′XX′ spin system.
Crystals of [RuCl(η2-N2H4)(η3-PP3iPr)]+Cl− (1) suitable for
X-ray crystallography were obtained on layering the reaction
mixture with diethyl ether. The crystal structure (Figure 3)
Figure 3. ORTEP plot of [RuCl(η2-N2H4)(η3-PP3iPr)]+Cl− (1), 50%
displacement ellipsoids, chloride counterion, and carbon-bound
hydrogen atoms excluded for clarity. Selected bond lengths (Å) and
angles (deg): Ru1−N1 2.1242(18), Ru1−N2 2.1324(18), N1−N2
1.444(2), N1−Ru1−N2 39.66(6), N1−Ru1−P4 96.17(7), N2−Ru1−
P4 97.50(7), N1−Ru1−P1 153.08(4), N2−Ru1−P1 113.45(6), N1−
Ru1−P2 108.36(6), N2−Ru1−P2 148.02(4), P1−Ru1−P2 98.53(5),
N1−Ru1−Cl1 82.62(7), N2−Ru1−Cl1 79.42(7), N2−N1−Ru1
70.48(8), N1−N2−Ru1 69.86(8).
Figure 1. Bonding modes of hydrazine, substituted hydrazine, and
substituted diazene complexes.
Scheme 1
clearly shows the side-on bound nature of the hydrazine ligand,
the uncoordinated phosphine arm (P3), and the fact that the
chloride ligand is trans to the central phosphorus (P4). The
geometry about ruthenium is that of a severely distorted
octahedron with an acute N1−Ru1−N2 angle of 39.66(6)° and
angles of 113.45(6), 108.36(6), and 98.53(5)° for N2−Ru1−
P1, N1−Ru1−P2, and P1−Ru1−P2, respectively. The Ru−N
bond lengths of 2.1242(18) and 2.1324(18) Å are within the
range for previously reported Ru hydrazine complexes (2.101−
2.273 Å).9,13,14 Short contacts were observed from the N atoms
of the hydrazine ligand to the chloride anion (3.073 and 3.169
Å), and these may contribute to the stability of the complex in
the solid state. Side-on bound hydrazine complexes are still
relatively rare15 and, so far, only one other side-on bound
hydrazine complex on ruthenium has been reported.9 The
hydrazine ligand is labile in solution without excess hydrazine.
Attempts to isolate the complex as the tetraphenylborate salt by
addition of NaBPh4 only afforded orange crystals of the chloro
chemical shifts to the solution chemical shifts with resonances
at δ 109.3, 95.9, 90.5, and 4.3. On labeling with 15N, the PT
resonance gains an extra splitting of about 21 Hz in the 31P{1H}
NMR spectrum while a single resonance at δ −364.7 is
observed in the 15N{1H} NMR spectrum indicating that the
hydrazine ligand is side-on bound trans to the two equivalent
phosphine arms (Figure 2). While the 15N resonance appears
superficially as a doublet, there is an underlying complexity due
12
complex [RuCl(PP3iPr)]+BPh4 .
−
Treatment of [RuCl(PP3iPr)]+Cl− with phenylhydrazine in
THF afforded the side-on bound phenylhydrazine complex
[RuCl(η2-NH2NHPh)(η3-PP3iPr)]+Cl− (2) (Scheme 1). The
31P{1H} NMR spectrum of the reaction mixture contained
resonances at δ 104.8, 83.9, 72.3, and 8.4 for the central
phosphine PC, terminal phosphines PT1, PT2, and the pendant
phosphine PF, respectively. Addition of pentane or hexane to
the reaction mixture afforded a pale yellow precipitate. The 31
P
solid state NMR spectrum of the precipitate showed four
resonances at δ 105.1 (PC), 72.1 (PT1), 68.1 (PT2), and 3.9
(PF). These chemical shifts are similar to the resonances
observed for the reaction mixture by solution 31P{1H} NMR
spectroscopy, where the chemical shift for PF is diagnostic of a
Figure 2. 15N{1H} NMR spectrum of [RuCl(η2-15N2H4)(η3-
PP3iPr)]+Cl− (1, methanol/THF/THF-d8, 41 MHz).
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pendant phosphine arm. The 31P solid state NMR spectrum is
consistent with the presence of a side-on bound phenyl-
hydrazine similar to that observed for the parent hydrazine
complex 1. The phenylhydrazine ligand in complex 2 is labile in
solution, and, on redissolving the precipitate, only signals for
[RuCl(PP3iPr)]+ and free phenylhydrazine were observed by
NMR spectroscopy.
Treatment of [RuCl(PP3iPr)]+Cl− with excess methylhydra-
zine in THF afforded the methylhydrazine complex [RuCl(η2-
NH2NHMe)(η3-PP3iPr)]+Cl− (3) (Scheme 1). The 31P{1H}
NMR spectrum of the reaction mixture exhibits multiple
resonances in the region δ 108−6 where up to 5 different
geometric isomers are possible, all with one phosphine arm
uncoordinated (Supporting Information). In one isomer, the
phosphine ligand is facially coordinated with the Cl ligand trans
to the central phosphine and the methylhydrazine ligand trans
to terminal phosphines, as for hydrazine complex 1 (Figure 4a).
Figure 5. ORTEP plot of [RuCl(η2-NH2NHMe)(η3-PP3iPr)]+Cl− (3),
50% displacement ellipsoids, chloride counterion, and carbon-bound
hydrogen atoms excluded for clarity. Only one of two independent
molecules is shown. Selected bond lengths (Å) and angles (deg):
Ru1−N1 2.116(4), Ru1−N2 2.173(5), N1−N2 1.452(6), N2−C25
1.474(7), N1−Ru1−N2 39.54(16), N1−Ru1−P4 96.74(13), N2−
Ru1−P4 94.76(13), N1−Ru1−P1 154.31(13), N2−Ru1−P1
114.79(12), N1−Ru1−P2 107.62(12), N2−Ru1−P2 146.92(12),
P1−Ru1−P2 98.06(5), N1−Ru1−Cl1 84.48(13), N2−Ru1−Cl1
85.75(13), N2−N1−Ru1 72.3(3), N1−N2−C25 113.4(4), N1−N2−
Ru1 68.1(3), C25−N2−Ru1 130.8(4).
98.06(5), respectively. Short contacts were observed from the
N atoms of the methylhydrazine ligand to the chloride
counterion (3.119−3.126 Å), and this may contribute to the
stability of the complex in the solid state. Methylhydrazine
preferentially binds end-on,16,17 and although bridging
examples are known,18 only one other example of side-on
binding19 has been crystallographically characterized.
Ph
Ru Hydrazine Complexes with the PP3 Ligand.
P h
Treatment of [RuCl2 (PP3 P h )] (PP3
= tris[2-
(diphenylphosphino)ethyl]phosphine) with excess hydrazine
in THF resulted in the substitution of one chloride ligand with
hydrazine to afford the end-on bound hydrazine complex
[RuCl(N2H4)(PP3Ph)]+ (4) (Scheme 2). On treatment with
NaBPh4 in methanol, complex 4 can be isolated as the
tetraphenylborate salt. The 31P{1H} NMR spectrum of 4
contains three resonances characteristic for an octahedral
complex with a tripodal tetradentate phosphine ligand. The low
field resonance at δ 142.5 is assigned to the central phosphine
PC, while the resonance at δ 59.2 is assigned to the unique
phosphine PU and the resonance at δ 34.1 with double the
intensity of the other signals to the two equivalent terminal
phosphines PT. The hydrazine signals in the 1H NMR spectrum
at δ 3.26 and 1.94 correlate to 15N signals at δ −344.8 and
Figure 4. Geometric isomers of [RuCl(η2-NH2NHMe)(η3-PP3iPr)]+
(3).
In another two isomers, the phosphine ligand is facially
coordinated with the Cl ligand trans to a terminal phosphine
(Figure 4b). A further two isomers arise from meridional
coordination of the phosphine ligand with the two terminal
phosphines trans to each other (Figure 4c). The 31P solid state
NMR spectrum is similar to that observed for hydrazine
complex 1 with resonances at δ 104.9, 96.8, 83.1, and −3.3
indicating that only one isomer is present in the solid state. As
observed for the analogous hydrazine complex 1, the
methylhydrazine ligand in 3 is labile in solution and efforts to
isolate the tetraphenylborate salt afforded only the chloro
1
−321.1, respectively, in a 2D H−15N HSQC (heteronuclear
single quantum coherence) experiment indicating that the
nitrogen atoms are in different chemical environments. On
labeling with 15N, an extra 31 Hz coupling is only observed for
PU in the 31P{1H} NMR spectrum indicating that the hydrazine
ligand is located trans to PU and that it must be end-on bound.
In the 15N{1H} NMR spectrum, the upfield signal exhibits a
reciprocal 31 Hz coupling to 31P indicating that it corresponds
to the NH2 directly bonded to Ru. The upfield signal also
exhibits a 6 Hz coupling to its partner nitrogen atom in the
hydrazine ligand. The downfield signal does not exhibit any
measurable 31P coupling and is assigned to the noncoordinated
NH2, again consistent with the fact that the hydrazine ligand is
complex [RuCl(PP3iPr)]+BPh4 .
−
Layering the reaction mixture of [RuCl(PP3iPr)]+Cl− and
methylhydrazine with diethyl ether afforded yellow crystals of
3. X-ray crystallographic analysis confirmed the side-on bound
nature of the methylhydrazine ligand and η3-coordination of the
tripodal phosphine ligand (Figure 5). The chloro ligand is trans
to the central phosphine (P4) indicating that geometric isomer
(a) was crystallized preferentially. The distorted octahedral
geometry about ruthenium is shown by the acute N1−Ru1−N2
angle of 39.54(16)° as well as angles for N2−Ru1−P1, N1−
Ru1−P2, and P1−Ru1−P2 of 114.79(12), 107.62(12), and
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Scheme 2
bound end-on. Microanalysis confirms that there is only one
coordinated hydrazine in the solid state for the tetraphenylbo-
rate salt of 4.
Although we were unable to grow crystals of hydrazine
complex 4 suitable for X-ray crystallography, we did obtain,
from the reaction mixture of [RuCl2(PP3Ph)] and hydrazine in
THF, crystals of the bis-substituted hydrazine complex
[RuCl(η1-N2H4)2(η3-PP3Ph)]+Cl− (5). The crystal structure of
5 (Figure 6) clearly shows two hydrazine ligands which are
arms coordinated was detected indicating first the lability of the
coordinated hydrazine and second that the structure in the
solid state differs from the structure in solution.
Treatment of [RuCl2(PP3Ph)] with phenylhydrazine or
methylhydrazine in THF similarly resulted in the substitution
of one chloride ligand to afford end-on bound hydrazine
complexes [RuCl(NH2NHR)(PP3Ph)]+ (R = Ph, 6; R = Me, 7)
(Scheme 2).
Layering of diethyl ether on the respective reaction mixtures
afforded crystals suitable for X-ray crystallography for both
complexes [RuCl(NH2NHR)(PP3Ph)]+ (R = Ph, 6; R = Me, 7)
(Figures 7 and 8). Both structures show an octahedral
Figure 6. ORTEP plot of [RuCl(η1-N2H4)2(η3-PP3Ph)]+Cl− (5), 50%
displacement ellipsoids, chloride counterion, carbon-bound hydrogen
atoms, and atoms of less than 50% occupancy excluded for clarity. It
was not possible to locate H atom positions on N3 and N4 due to
disorder over two positions. Selected bond lengths (Å) and angles
(deg): Ru1−N3 2.219(5), Ru1−N1 2.239(4), N1−N2 1.484(6), N3−
N4 1.382(8), N3−Ru1−N1 81.18(17), N2−N1−Ru1 121.3(3), N4−
N3−Ru1 125.7(5).
Figure 7. ORTEP plot of [RuCl(NH2NHPh)(PP3Ph)]+Cl− (6), 50%
displacement ellipsoids, only one of two independent molecules
shown. Three phenylhydrazine solvates, chloride counterion, and
carbon-bound hydrogen atoms excluded for clarity. Selected bond
lengths (Å) and angles (deg): Ru1−N1 2.210(3), N1−N2 1.436(4),
N2−C43 1.429(4), N2−N1−Ru1 123.91(19), C43−N2−N1
116.1(3).
both trans to terminal phosphines (P1 and P3) and bound end-
on. One arm of the phosphine ligand is a pendant arm and not
coordinated to the metal and the chloride ligand is trans to the
central phosphorus atom (P4). The Ru−N bond lengths of
2.219(5) and 2.239(4) Å and N−N bond lengths of 1.484(6)
and 1.382(8) Å are within the range reported for other
ruthenium end-on bound hydrazine complexes (2.126−2.273
and 1.377−1.479 Å, respectively).9,13 Short contacts were
observed from the N atoms of the hydrazine ligands to the
chloride counterion (3.205−3.282 Å), and this may contribute
to the stability of the bis hydrazine complex in the solid state.
Bis-substituted hydrazine complexes have been structurally
characterized previously and are known to bind end-on9,20 and
bridging.21 The 31P solid state NMR spectrum of the bulk of
the crystals shows resonances at δ 106.7, 63.3, 58.8, and −2.4
for the central phosphine PC, two terminal phosphines PT1, PT2,
and the pendant phosphine PF consistent with the crystal
structure above. When the crystals were dissolved, only the
presence of the monosubstituted complex 4 with all phosphine
arrangement of atoms around the metal center with the
chloride ligand trans to the central phosphorus (P4). Both
phenylhydrazine and methylhydrazine ligands are bound end-
on via the NH2 group. The N−N bond lengths of the two
independent molecules of phenylhydrazine complex 6
(1.436(4), 1.445(4) Å) are within the range reported previously
for end-on bound phenylhydrazine complexes (1.41−1.545
Å)7,22−24 although the Ru−N bonds (2.210(3), 2.222(3) Å) are
slightly shorter than the Ru−N bond for [RuCl(NH2NHPh)-
(dmpe)2]+ (2.2504(19) Å).7 The N−N bond length (1.450(2)
Å) for methylhydrazine complex 7 is within the range reported
for other end-on bound methylhydrazine complexes (1.421−
1.458 Å).7,17,22,25,26 The Ru−N bond length (2.2103(15) Å) is
similar to that for [RuCl(NH2NHMe)(dmpe)2]+ where dmpe
=1,2-bis(dimethylphosphino)ethane (2.1965(18) Å)7 and
significantly longer than the Ru-methylhydrazine bond in
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Scheme 3
15N NMR spectra for [Ru(15N2)(PP3iPr)] match those reported
previously.12 The use of the 15N labeled substrate first confirms
that N2 observed in the product is derived from the labeled
hydrazine in 1 and second allows 15N NMR spectroscopy to be
used as a further line of evidence to verify the identity of the
product.
The reaction probably proceeds by initial deprotonation of
the hydrazine species to afford the side-on bound diazene
complex (Scheme 4). This first step has been observed in Ru
Figure 8. ORTEP plot of [RuCl(NH2NHMe)(PP3Ph)]+Cl− (7), 50%
displacement ellipsoids, THF solvate, chloride counterion, and carbon-
bound hydrogen atoms have been excluded for clarity. Selected bond
lengths (Å) and angles (deg): Ru1−N1 2.2103(15), N1−N2 1.450(2),
N2−C43 1.468(2), N2−N1−Ru1 123.50(11), N1−N2−C43
110.66(14).
Scheme 4
[Ru(Tp)(NH2NHMe){P(OEt)3}(PPh3)] where Tp =
hydridotris(pyrazolyl)borate (2.154(3) Å)26 probably due to
the stronger trans influence of the P atom trans to the
methylhydrazine ligand in 7 compared to that of the trans N
atom in [Ru(Tp)(NH2NHMe){P(OEt)3}(PPh3)].
Both phenylhydrazine complex 6 and methylhydrazine
complex 7 can be isolated as the respective tetraphenylborate
salts on treatment with NaBPh4 in methanol. The 31P{1H}
NMR spectrum of phenylhydrazine complex 6 contains three
signals at δ 139.8, 59.0, and 32.4 in a ratio of 1:1:2 for PC, PU,
and PT, respectively. The 31P solid state NMR spectrum is
similar to the solution spectrum with resonances at δ 140.4,
59.4, 37.0, and 30.4 as expected for a complex with all four
phosphine atoms coordinated to the metal. In a 1H−15N
correlation experiment, the broad 1H signal integrating to three
protons at δ 3.70 correlates to two 15N signals at δ −284.8 and
−328.4 for NHPh and RuNH2, respectively. The 1H signal at δ
5.44 correlates to a 13C signal at δ 112.6 indicating that it is due
to CH protons. This highly shielded signal for aromatic protons
is likely due to the ortho protons of the phenylhydrazine ligand
which are located in the shielding zone (close to the face) of
two PP3Ph phenyl groups as also seen in the crystal structure of
6 (Figure 7).
dmpe and depe (depe = 1,2-bis(diethylphosphino)ethane)
systems where side-on bound diazene complexes have been
isolated and characterized.9 Transfer of electrons onto Ru and
into the N−N bond affords a Ru(0) end-on bound diazene
complex. Disproportionation of the diazene with loss of H2 or
loss of N2 forms the Ru dinitrogen and dihydride complexes.
Synthesis and Characterization of [RuH2(PP3iPr)]. The
Ru dihydride complex [RuH2(PP3iPr)] (8) has not been
previously reported and was synthesized independently by
treatment of [RuCl(PP3iPr)]+Cl− with sodium in liquid
ammonia or potassium triethylborohydride (KBEt3H) in
Similarly, for methylhydrazine complex 7, three resonances
in a ratio of 1:1:2 at δ 140.5, 57.6, and 33.4 are observed in the
31P{1H} NMR spectrum for PC, PU, and PT, respectively. In a
1
1H−15N HSQC experiment, the H NMR signals at δ 3.04
1
(integrating to two protons) and δ 1.50 (integrating to one
benzene or toluene under argon. The H NMR spectrum
proton) correlate to 15N signals at δ −314.5 and −309.6 for
exhibits a single broad resonance at −9.13 ppm for the hydride
ligands. The 31P{1H} NMR spectrum contains a quartet at
154.2 ppm and a doublet at 91.8 ppm in a ratio of 1:3. These
features are consistent with exchange occurring between the
hydride ligands as well as between the terminal phosphorus
environments. On lowering the temperature, the single hydride
resonance separates into two signals while the two phosphorus
signals give three broad signals in a ratio of 1:2:1 (Figure 9).
Such exchange has been observed previously for analogous
dihydride complexes with tripodal tetraphosphine ligands.27
Crystals of 8 suitable for X-ray crystallography were obtained
by slow evaporation of a benzene/benzene-d6 solution under
argon (Figure 10). The geometry of the complex is distorted
1
RuNH2 and NHMe, respectively. The H NMR signal for the
methyl protons of the methylhydrazine ligand is shifted upfield
to δ 0.80 as the protons are located in the shielding zone of two
phenyl groups from the PP3Ph ligand, and this can also be seen
in the crystal structure of 7 (Figure 8).
Base-Induced Dehydrogenation of Ru Hydrazine
Complexes. [RuCl(η2-15N2H4)(η3-PP3iPr)]+Cl− (1). Treatment
of 15N-labeled hydrazine complex [RuCl(η2-15N2H4)(η3-
PP3iPr)]+Cl− (1) with KOtBu in THF-d8 afforded the Ru(0)
dinitrogen [Ru(15N2)(PP3iPr)] and Ru dihydride
[RuH2(PP3iPr)] (8) complexes in a ratio of 1:1.2 (NMR yields
1
of 44% and 54%, respectively) (Scheme 3). The H, 31P, and
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Scheme 5
Figure 9. High field 1H (a) and 31P{1H} (b) NMR spectra of
[RuH2(PP3iPr)] (8) (d8-toluene, 600 and 243 MHz).
either side of the face) of the five-membered diazoruthenacycle.
1
In a H−15N HSQC experiment, the diazene proton correlates
to a 15N signal at δ 2.4 which is well within the range of
reported chemical shifts for aryldiazenyl NH nitrogens (δ 43.6
to −110.7).26,32 The 15N NMR chemical shift for the aryl N
was located at δ 110.7 after synthesizing a 15N-labeled complex
[RuH(C6H415NNH)(η3-PP3iPr)]. In the 31P{1H} NMR
spectrum, three signals are observed at δ 103.4, 92.5, and 8.2
in a ratio of 1:2:1 for the central phosphine, the two equivalent
terminal phosphines, and a free pendant phosphine arm,
respectively. Given the presence of three different ligands in the
molecule (hydride and cyclometalated phenyldiazene), the only
arrangement where the terminal phosphines are equivalent is
one where the terminal phosphines are trans to each other.
Crystals suitable for X-ray crystallography were grown by
slow evaporation of a toluene solution of 9 (Figure 11). The
crystal structure confirms the presence of an orthometalated
phenyldiazene ligand, a hydride ligand and the meridional
iPr
Figure 10. ORTEP plot of [RuH2(PP3iPr)] (8), 50% displacement
ellipsoids, carbon bound hydrogen atoms excluded for clarity. Selected
bond lengths (Å) and angles (deg): Ru1−P4 2.2322(3), Ru1−P3
2.3002(3), Ru1−P1 2.3090(3), Ru1−P2 2.3415(3), P4−Ru1−P3
84.256(10), P4−Ru1−P1 84.565(10), P3−Ru1−P1 147.883(10), P4−
Ru1−P2 85.671(11), P3−Ru1−P2 100.792(10), P1−Ru1−P2
108.259(10).
arrangement of the PP3 ligand with two mutually trans
terminal phosphine arms and one free phosphine arm. The
cyclometalated aryldiazene motif has so far only been observed
for iridium complexes, of which several have been crystallo-
octahedral with the hydride ligands in mutually cis positions.
The structure is analogous to those of [RuH2(P-
(CH2CH2CH2PiPr2)3)]28 (which contains the related tetra-
phosphine ligand with 3-carbon instead of 2-carbon linkers
b e t w e e n t h e p h o s p h i n e s ) a n d [ R u H 2 ( P -
(CH2CH2CH2PMe2)3)]29 (which also contains 3-carbon link-
ers as well as methyl substituents instead of isopropyl
substituents on the terminal phosphines). The PC−Ru-PT/PU
angles (84.257(10)−85.671(11)°) are smaller than those of
[RuH2(P(CH2CH2CH2PiPr2)3)] (89.45(4)−94.75(4)°) and
[RuH2(P(CH2CH2CH2PMe2)3)] (90.8(2)−96.4(2)°) reflect-
ing the more constrained environment of the ligand with 2-
carbon linkers compared to those with 3-carbon linkers.
[RuCl(η2-NH2NHPh)(η3-PP3iPr)]+Cl− (2). In contrast to the
complex with unsubstituted hydrazine, treatment of phenyl-
hydrazine complex [RuCl(η2-NH2NHPh)(η3-PP3iPr)]+Cl− (2)
with KOtBu in THF afforded the hydrido ruthenaindazole
complex [RuH(C6H4NNH)(η3-PP3iPr)] (9) as an orange
solid (Scheme 5). In the 1H NMR spectrum, a hydride
resonance at δ −12.52 and only four aromatic signals at δ 8.08,
8.01, 6.83, and 6.71 which (except for the signal at δ 6.83)
exhibit small couplings to 31P indicate the presence of a
cyclometalated phenyl ring. A singlet at δ 14.75 is observed for
NH at a typical chemical shift for an end-on bound aryldiazene
ligand (δ 11−17).26,30−32 1H signals for two sets of methyl
protons from the phosphine ligand are shifted upfield to δ
−0.02 as these protons are in the shielding zone (directly on
Figure 11. ORTEP plot of [RuH(C6H4NNH)(η3-PP3iPr)] (9), 50%
displacement ellipsoids, toluene solvate and carbon-bound hydrogen
atoms excluded for clarity. Selected bond lengths (Å) and angles
(deg): Ru1−N1 2.0388(14), Ru1−C32 2.0781(16), Ru1−P4
2.2642(4), Ru1−P1 2.2803(4), Ru1−P2 2.2934(4), Ru1−H
1.581(18), N1−N2 1.2911(19), N2−C37 1.395(2), C32−C37
1.424(2), N1−Ru1−C32 75.76(6), N1−Ru1−P4 103.15(4), N1−
Ru1−P1 104.46(4), P4−Ru1−P1 84.837(16), N1−Ru1−P2
104.73(4), P4−Ru1−P2 83.788(16), P1−Ru1−P2 150.381(17),
N1−Ru1−H 170.2(6), N2−N1−Ru1 123.25(11), N1−N2−C37
110.52(13), C37−C32−Ru1 111.93(12), N2−C37−C32 118.54(14).
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graphically characterized.33 The N−N bond distance of
1.2911(19) Å in 9 is similar to those in cyclometalated
aryldiazene iridium complexes (1.24−1.28 Å) and within the
range reported for other aryldiazene complexes (1.13−1.373
Å)31,34 clearly indicating the presence of an N−N double bond.
The N−C bond distance of 1.395(2) Å is also shorter than the
analogous bond in phenylhydrazine complex [RuCl-
(NH2NHPh)(PP3Ph)]+ (6) (1.429(4) Å) indicating partial
delocalization of the nitrogen lone pair into the phenyl ring. In
fact, the planarity of the ruthenacycle and attached phenyl ring
indicates delocalization of electrons throughout the bicyclic
structure such that the cyclometalated phenyldiazene moiety
can be considered a benzopyrrole or indazole molecule with a
ruthenium metal in place of a carbon atom. The aromaticity of
the ruthenaindazole moiety is borne out by the significant
upfield shifts of the methyl protons located on either side of the
face of the ring.
Scheme 7
complex was characterized by NMR spectroscopy as soon as
possible after synthesis.
1
In the H NMR spectrum of [RuH(NHNCH2)(PP3iPr)]
(10), two doublets at δ 6.28 and 5.54 with13.5 Hz coupling are
observed for the methylene protons. A doublet at δ 5.27 with a
7.1 Hz coupling to 31P is observed for NH, and a metal hydride
signal is observed at δ −10.69. All signals integrate in a ratio of
1:1:1:1. The 31P{1H} NMR spectrum indicates that all four P
atoms are bound to Ru with signals at δ 145.4, 63.5, and 52.9
for PC, PT, and PU, respectively. The methylene protons
The reaction probably proceeds initially by stepwise
deprotonation of the NHPh end of the phenylhydrazine ligand
and then deprotonation of the NH2 group to give a side-on
bound phenyldiazene ligand (Scheme 6). These steps have
correlate to a single 13C signal at δ 104.4 in a H−13C HSQC
1
experiment while the NH proton correlates to a 15N signal at δ
−266.4 in a low temperature 1H−15N HSQC experiment
(Figure 12). No three-bond correlation is detected in a 1H−15N
HMBC experiment even at low temperature for Nβ.
Scheme 6
Figure 12. (a) H−13C HSQC spectrum (toluene-d8, 298 K, 600 and
1
been observed for Ru dmpe complexes where the side-on
phenylhydrazide and phenyldiazene complexes have been
isolated and characterized.7 Subsequent transfer of electrons
onto Ru and into the N−N bond affords a Ru(0) end-on
bound phenyldiazene complex. Oxidative addition of the
phenyl group affords the final hydrido ruthenaindazole complex
9. This is the first report of an end-on bound phenyldiazene
complex being formed on base treatment of a phenylhydrazine
complex. It is also the first route to a cyclometalated
phenyldiazene by base treatment of phenylhydrazine. The
known iridium cyclometalated aryldiazene complexes have been
synthesized by reaction of iridium precursor complexes such as
[IrCl(CO)(PPh3)2], [IrH3(PPh3)3], [IrH(CO)(PPh3)3], [IrH-
(CO)2(PPh3)2], or [Ir2(CO)6(PPh3)2] with aryldiazonium
salts.33,35
151 MHz) and (b) 1H−15N HSQC spectrum (toluene-d8, 200 K, 600
and 61 MHz) of [RuH(NH-NCH2)(PP3iPr)] (10).
Formation of methylenehydrazide complex 10 probably
proceeds initially by deprotonation of the methylhydrazine
ligand to afford the side-on bound methyldiazene complex
(Scheme 8), and an analogous complex has been observed for
Ru with dmpe coligands.7 Electron transfer onto Ru and into
the N−N bond leading to decoordination of the NMe end
affords a Ru(0) methyldiazene species. Hydride transfer from
the methyl group to the Ru center with electron redistribution
effectively oxidizes Ru(0) to Ru(II) and furnishes the final
hydrido methylenehydrazide complex 10.
While we have assigned 10 as the methylenehydrazide
complex, we cannot completely eliminate the possibility that
the nitrogenous ligand could be methyleneimine (NHCH2)
rather than (−NH-NCH2). Albertin and co-workers36 have
reported the formation of methyleneimine complex [Re(NH
CH2)(CO)P4]+ (P = P(OEt)3) as a mixture with methyldiazene
complex [Re(NHNCH3)(CO)P4]+ on treatment of methyl-
hydrazine complex [Re(NH2NHMe)(CO)P4]+ with Pb(OAc)4
at low temperature. The rhenium methyleneimine complex has
[RuCl(η2-NH2NHMe)(η3-PP3iPr)]+Cl− (3). Treatment of meth-
ylhydrazine complex [RuCl(η2-NH2NHMe)(η3-PP3iPr)]+Cl−
(3) with KOtBu for 5−10 min in THF followed by a quick
pentane extraction afforded a mixture of products and we assign
the major product as the hydrido 2-methylenehydrazido
complex [RuH(NHNCH2)(PP3iPr)] (10) (Scheme 7).
Longer reaction times afforded significant amounts of
unidentified products. The methylenehydrazide complex 10 is
unstable both in solution and in the solid state, and the
1
a broad H NMR signal at δ 13.98 for the NH proton and a
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Scheme 8
Scheme 9
Scheme 10
slightly broadened multiplet at δ 3.66 which couples to the NH
proton for one of the two NCH2 methylene protons (the
other methylene proton likely masked by P ligand signals).
Albertin et al. have also reported the base-induced tautomeriza-
tion of methyldiazene complexes [M(NHNCH3)(CO)P4]2+
(M = Ru, Os; P = P(OEt)3) to formaldehyde hydrazone
complexes [M(NH2NCH2)(CO)P4]2+ where broad 1H
NMR signals at δ 5.86 (M = Ru) and δ 6.26 (M = Os) are
observed for the NH2 groups and AB quartets (JAB = 9.3 Hz) at
δ 6.67 (M = Ru) and 6.54 (M = Os) for the methylene
protons.37 The 1H NMR data for complex 10 is more
consistent with that for a methylenehydrazide ligand given
that the NH resonance is not to low field (i.e., not between δ
11−14) and no coupling is observed from the NH to the
methylene protons as reported for free methyleneimine38 and
methyleneimine complexes.36,39 In addition, a methyleneimine
complex would be charged and unlikely to be pentane soluble.
Both mono40 and bis-substituted41 methylenehydrazide
(−NHNCHR and −NHNCRR′) complexes are known,
but to the best of our knowledge, methylenehydrazide complex
10 is the first report of a complex containing a parent
methylenehydrazide (−NHNCH2) ligand. Complex 10 is
unstable both in solution and solid states and decomposes over
time to afford dinitrogen complex [Ru(N2)(PP3iPr)] and other
unidentified products.
(at δ 6.28) shows a dramatic reduction in the intensity of the
upfield methylene proton (at δ 5.54) by saturation transfer,
indicating chemical exchange between the methylene protons.
The rate of exchange was measured to be approximately 2.8 s−1
at 298 K using an inversion-transfer-recovery experiment42 (see
the Supporting Information), and this translates to an activation
barrier for the exchange process of about 70.4 kJ mol−1. A
reasonable rationalization for the facile exchange is that there is
an allylic-type delocalization of electrons across the methyl-
enehydrazide ligand (Scheme 9) which facilitates rotation about
the NC bond.
Base-Induced Reaction of [RuCl(15N2H4)(PP3Ph)]+ (4),
[RuCl(NH2NHPh)(PP3Ph)]+ (6) [RuCl(NH2NHMe)(PP3Ph)]+ (7).
In an analogous reaction to that for [RuCl(η2-15N2H4)(η3-
PP3iPr)]+ (1), treatment of 15N-labeled hydrazine complex
[RuCl(15N2H4)(PP3Ph)]+ (4, chloride or tetraphenylborate salt)
with KOtBu in THF-d8 afforded the Ru(0) dinitrogen
[Ru(15N2)(PP3Ph)] and Ru dihydride [RuH2(PP3Ph)] com-
plexes in a ratio of 6:1 (NMR yields of approximately 72% and
13%, respectively) (Scheme 10). The resonances in the 1H, 31P,
and 15N NMR spectra are identical to those for the relevant
complexes as previously reported in the literature.43,44
Similarly, treatment of phenylhydrazine complex [RuCl-
(NH2NHPh)(PP3Ph)]+ (6) or methylhydrazine complex
[RuCl(NH2NHMe)(PP3Ph)]+ (7) with KOtBu under argon
afforded the dinitrogen complex [Ru(N2)(PP3Ph)] (85% yield
by NMR) and benzene (87% yield by NMR) or methane (39%
yield by NMR; the yield of methane is probably understated
An unusual feature of [RuH(NHNCH2)(PP3iPr)] (10) is
the evidence of chemical exchange between the methylene
protons. Selective saturation of the downfield methylene signal
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Table 1. Crystallographic Data for [RuCl(η2-N2H4)(η3-PP3iPr)]+Cl− (1), [RuCl(η2-NH2NHMe)(η3-PP3iPr)]+Cl− (3), [RuCl(η1-
N2H4)2(η3-PP3Ph)]+Cl− (5), [RuCl(NH2NHPh)(PP3Ph)]+Cl− (6), [RuCl(NH2NHMe)(PP3Ph)]+Cl− (7), [RuH2(PP3iPr)] (8), and
[RuH(C6H4NNH)(η3-PP3iPr)] (9)
1
3
5
6
7
8
9
formula
C24H58Cl2N2P4Ru
670.57
C25H60Cl2N2P4Ru
684.60
C42H46Cl2N4P4Ru
902.68
C114H124Cl4N10P8Ru
2225.93
C90H104Cl4N4OP8Ru2 C24H56P4Ru
C37H68N2P4Ru
765.88
M (g mol−1
size (mm3)
)
1849.47
569.64
0.40 × 0.30 × 0.28 0.40 × 0.30 × 0.25 0.20 × 0.18 × 0.16 0.30 × 0.25 × 0.23
0.30 × 0.20 × 0.20
0.40 × 0.30 ×
0.26
0.25 × 0.20 ×
0.15
crystal
colorless block
colorless block
colorless block
colorless block
colorless block
colorless block orange block
morphology
crystal system
space group
a (Å)
orthorhombic
Pbca
monoclinic
P21/c (no. 14)
13.6590(10)
18.7193(14)
26.3192(18)
90
monoclinic
P21/c (no.14)
14.411(16)
29.81(4)
9.912(11)
90
monoclinic
Cc
orthorhombic
Ibca
monoclinic
P21/n (no.14)
10.7083(4)
19.7253(8)
14.3069(6)
90
triclinic
P-1
13.693(11)
18.134(15)
26.76(2)
90
12.117(11)
27.59(3)
34.12(3)
90
17.3284(9)
26.8150(12)
36.139(3)
90
12.2635(5)
13.1418(5)
14.6359(5)
78.7060(10)
71.3070(10)
64.7060(10)
2015.36(13)
2
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
90
91.681(3)
90
100.35(3)
90
100.23(2)
90
90
107.7170(10)
90
90
90
V (Å3)
6 643(9)
8
6 726.6(8)
8
4 188(8)
4
11 228(19)
4
16 792.2(16)
8
2 878.6(2)
4
Z
Dc (g/cm3)
1.341
1.352
1.432
1.317
1.463
1.314
1.262
μ (mm−1
)
0.841
0.833
0.690
0.529
0.690
0.777
0.574
F(000)
2 832
2 896
1 856
4 616
7 648
1 216
816
2θmax (deg)
60.9
53.5
49.8
52.7
54.4
62.0
54.2
N
79 190
55 357
24 036
86 165
125 524
38 868
32 206
Nind
10 066 (Rint
0.0444)
=
14 250 (Rint
0.0646)
=
7 113 (Rint
0.0949)
=
21 821 (Rint = 0.0294) 9 285 (Rint = 0.0347) 9 166 (Rint
=
8 870 (Rint =
0.0264)
0.0251)
Nobs (I > 2σ(I))
goodness of fit
8 435
1.047
10 628
1.199
4 422
20 628
1.041
8 177
8 265
7 762
0.984
1.040
1.046
1.023
R1 (F, I > 2σ(I)) 0.0258
wR2 (F2, all data) 0.0563
0.0602
0.1144
0.0504
0.0867
0.0325
0.0779
0.011(13)
0.0251
0.0596
0.0187
0.0447
0.0259
0.0535
absolute structure
parameter
due to loss of methane gas from solution into the head space of
the reaction mixture), respectively. Reduction of coordinated
phenylhydrazine to ammonia and aniline has been re-
ported.3,17,24,45 Reduction of methylhydrazine to ammonia
and methylamine has also been reported.3,4 Only one report
details the formation of dinitrogen and benzene as a mixture
with ammonia and aniline from phenylhydrazine.46 As far as we
are aware, there is no precedent for the formation of dinitrogen
and methane from coordinated methylhydrazine. The reactions
of hydrazine complexes 4, 6, and 7 with base probably proceed
through a mechanism analogous to that proposed for the
reaction of [RuCl(η2-N2H4)(η3-PP3iPr)]+ (1) with base
(Scheme 4) but with loss of benzene or methane, respectively,
for complexes 6 and 7.
containing a cyclometalated phenyldiazene ligand. This is the
first report of formation of an end-on bound phenyldiazene
ligand by base treatment of the phenylhydrazine ligand.
The base treatment of methylhydrazine complex [RuCl(η2-
NH2NHMe)(η3-PP3iPr)]+ affords the hydrido methylenehydra-
zide complex [RuH(NHNCH2)(PP3iPr)], and this the first
report of a complex containing the parent methylenehydrazide
ligand.
These reactions, where the Ru center is coordinated by a
hindered tripodal PP3 ligand, in contrast to those reported for
Ru complexes with bidentate ligands dmpe and depe, where
side-on bound diazene complexes were isolated as stable
complexes. These results exemplify how changes in the ligand
environment can dramatically impact the reactivity pathways of
ruthenium hydrazines and may be due to a number of factors
including the balance between the steric and electronic effects
of the tripodal phosphine ligands.
CONCLUSIONS
■
We have reported the synthesis of tripodal phosphine (PP3
where PP3 = PP3 = P(CH2CH2PiPr2)3 and PP3
=
iPr
Ph
EXPERIMENTAL SECTION
P(CH2CH2PPh2)3) complexes of Ru containing hydrazine,
phenylhydrazine, and methylhydrazine ligands.
■
All manipulations of metal complexes and air-sensitive reagents were
carried out using standard Schlenk techniques or in nitrogen or argon
filled glove boxes. Solvents were dried and distilled under nitrogen or
argon from sodium/benzophenone (benzene) and dimethoxymagne-
sium (methanol). Tetrahydrofuran, diethyl ether, toluene, and pentane
were dried and deoxygenated using a Pure Solv 400-4-MD (Innovative
Technology) solvent purification system. Deuterated solvents were
purchased from Cambridge Isotope Laboratories. Tetrahydrofuran-d8,
benzene-d6, and toluene-d8 were dried over and distilled from sodium/
benzophenone. Hydrazine (1 M in THF) was purchased from Aldrich
and deoxygenated before use. Hydrazine-15N2 was prepared by Soxhlet
extraction of 15N2H4·H2SO4 with liquid ammonia.47 Methylhydrazine
Treatment of the Ru hydrazine complexes with base
(butoxide) affords the Ru(0) dinitrogen complexes and the
Ru dihydride complexes. Treatment of the phenylhydrazine
complex [RuCl(NH2NHPh)(PP3Ph)]+ with base affords the
Ru(0) dinitrogen complex and benzene. Treatment of the
methylhydrazine complex [RuCl(NH2NHMe)(PP3Ph)]+ with
base affords the Ru(0) dinitrogen complex and methane.
The treatment of phenylhydrazine complex [RuCl(η2-
NH2NHPh)(η3-PP3iPr)]+ with base affords a new hydrido
ruthenaindazole complex [RuH(C6H4NNH)(η3-PP3iPr)]
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was dried over barium oxide, vacuum distilled, and stored over
activated molecular sieves under nitrogen. Phenylhydrazine was
vacuum distilled and stored over activated molecular sieves under
nitrogen. Ph15NHNH2 was prepared by diazotization of aniline-15N
with sodium nitrite (unlabeled) and subsequent reduction with
sodium sulfite. Potassium t-butoxide was sublimed twice and stored
under an inert atmosphere. Potassium triethylborohydride (KBEt3H)
was synthesized by reaction of equimolar amounts of potassium
hydride and triethylboron in toluene and hexane. Tris[2-
(diphenylphosphino)ethyl]phosphine (PP3Ph) was purchased from
Aldrich and used without further purification. [RuCl2(PP3Ph)] was
prepared from [RuCl2(PPh3)3] according to the literature method.43
Tris[2-(diisopropylphosphino)ethyl]phosphine (PP3iPr) and [RuCl-
(PP3iPr)]+Cl− were prepared according to the literature method.12
Air-sensitive NMR samples were prepared in argon or nitrogen
filled glove boxes or on a high vacuum line by vacuum transfer of
The 15N-labeled analogue was prepared in a similar manner using
[RuCl(PP3iPr)]+Cl− (0.103 g, 0.161 mmol) and Ph15NHNH2 (0.249 g,
2.30 mmol) to afford [RuCl(NH215NHPh)(PP3iPr)]+Cl− (0.116 g,
0.125 mmol, 78%).
[RuCl(η2-NH2NHMe)(η3-PP3 iPr)]+Cl− (3). Methylhydrazine (0.2
mL, 4 mmol) was added to a suspension of [RuCl(PP3iPr)]+Cl− (0.136
g, 0.213 mmol) in THF (2 mL) under nitrogen to give a yellow
solution. 31P{1H} NMR (methylhydrazine/THF/THF-d8, 162 MHz):
2
δ 105.9 (q, JPP 19 Hz, 4.4P), 104.1 (m, 1P), 103.3 (m, 1.3P), 101.9
(dt, 2JPP 26 Hz, 2JPP 19 Hz, 1.4P), 99.9 (q, 2JPP 20 Hz, 4P), 92.3 (t, 2JPP
16 Hz, 4.4P), 91.5 (m, 1.3P), 89.9 (m, 1.5P), 88.6 (t, 2JPP 17 Hz, 4P),
88.2 (m, 1P), 81.4 (t, 2JPP 22 Hz, 1.2P), 72.3 (d, 2JPP 20 Hz, 8.2P), 70.8
(m, 1P), 64.7 (dd, 2JPP 24 Hz, 2JPP 19 Hz, 1.2P), 10.0 (m, 1.3P), 9.4−
8.1 (m, 10.5P). Diethyl ether (6 mL) was added and yellow crystals
precipitated from the reaction mixture overnight. The product was
collected by filtration, washed with diethyl ether, then dried in vacuo
(0.129 g, 0.188 mmol, 88%). C25H60Cl2N2P4Ru (684.72) requires C,
43.9; H, 8.9; N, 4.1; found C, 44.0; H, 8.9; N, 4.1%. 31P solid state
NMR: δ 104.9 (1P, PC), 96.8 (1P, PT1), 83.1 (1P, PT2), −3.3 (1P, PF).
IR: 3248w, 3155w, 3079m, 1584s, 1402m, 1379s, 1315w, 1251m,
1183m, 1157w, 1099m, 1061m, 1044s, 1021s, 988w, 965w, 928w,
900m, 885m, 841w, 817m, 784m, 722s, 709s, 691s, 656s, 630m, 616s
cm−1.
1
solvent into an NMR tube fitted with a concentric Teflon valve. H,
31P, and 15N NMR spectra were recorded on Bruker Avance III 600,
400 or DPX 300 NMR spectrometers at 298 K unless otherwise stated.
1H NMR spectra were referenced to residual solvent resonances while
31P spectra were referenced to external neat trimethyl phosphite at δ
140.85 ppm. 15N NMR spectra were reference to external neat
nitromethane at δ 0.0 ppm. Simulation of 31P spectra were performed
iteratively using the simulation program NUMMRIT (SpinWorks 3)
where signs for coupling constants are not implied. Infrared spectra
were recorded on a Nicolet Avatar 360 FTIR spectrometer as nujol
mulls. 31P solid state NMR spectra were recorded on a Bruker Avance
III 300 MHz solid state spectrometer equipped with an Oxford 300
magnet. Samples were spun in a 4 mm rotor at 12 or 14 kHz and
spectra were referenced to external ammonium dihydrogen phosphate
(ADP) at δ 1.0. Mass spectrometric analyses were carried out at the
Bioanalytical Mass Spectrometry Facility, UNSW. Microanalyses were
carried out at the Campbell Microanalytical Laboratory, University of
Otago, New Zealand. X-ray crystallography was carried out on a
Bruker Nonius X8 Apex II CCD diffractometer (MoKα radiation, λ =
0.710 73 Å, T = 100(2) K). Crystallographic data are presented in
Table 1.
[RuCl(N2H4)(PP3Ph)]+X− (4). XCl. [RuCl2(PP3Ph)] (53 mg, 63
μmol) was dissolved in a hydrazine solution (1 M in THF, 2 mL, 2
mmol) under nitrogen to give a yellow solution. On standing for
several days, a yellow crystalline solid precipitated from the reaction
mixture. The product was collected by filtration and washed with
THF. The product was used directly in the next step without further
2
purification. 31P{1H} NMR (MeOH, 122 MHz): δ 144.9 (dt, JPC‑PU
2
2
11.1 Hz, JPC‑PT 10.9 Hz, 1P, PC), 60.2 (dt, JPU‑PT 25.2 Hz, 1P, PU),
35.1 (dd, 2P, PT). Crystals of [RuCl(η1-N2H4)2(η3-PP3Ph)]+Cl− (5)
suitable for X-ray crystallography were obtained from a similar reaction
mixture as above which was left to stand at room temperature for
several days. 31P solid state NMR: δ 106.7 (1P, PC), 63.3 (1P, PT1),
58.8 (1P, PT2), −2.4 (1P, PF).
The 15N-labeled analogue [RuCl(15N2H4)(PP3Ph)]+Cl− was pre-
pared in a similar manner using 15N2H4. 31P{1H} NMR (MeOH, 121
MHz): δ 144.9 (dt, 2JPC‑PU 10.9 Hz, 2JPC‑PT 10.9 Hz, 1P, PC), 60.1 (ddt,
[RuCl(η2-N2H4)(η3-PP3 iPr)]+Cl− (1). Methanol (0.4 mL) was added
to a suspension of [RuCl(PP3iPr)]+Cl− (93 mg, 0.15 mmol) in
hydrazine (1 M in THF, 1 mL, 1 mmol) under nitrogen to give a
yellow solution. 31P{1H} NMR (hydrazine/MeOH/THF, 122 MHz):
δ 108.3 (dt, 2JPC‑PT 18 Hz, 2JPC‑PF 21 Hz, 1P, PC), 91.6 (d, 2P, PT), 8.3
(d, 1P, PF). Diethyl ether (5 mL) was added, and yellow crystals
precipitated from the reaction mixture overnight. The product was
collected by filtration, washed with diethyl ether, then dried in vacuo
(74 mg, 0.11 mmol, 74%). C24H58Cl2N2P4Ru (670.69) requires C,
43.0; H, 8.7; N, 4.2; found C, 43.2; H, 8.8; N, 4.2%. 31P solid state
NMR: δ 109.3 (1P, PC), 95.9 (1P, PT1), 90.5 (1P, PT2), 4.3 (1P, PF).
IR: 3282m, 3189w, 3113w, 2748w, 1592m, 1561m, 1418m, 1368m,
1245m, 1183w, 1159m, 1139w, 1121w, 1113w, 1100w, 1068w, 1048m,
1026w, 994w, 964w, 930w, 896m, 891m, 885m, 840w, 811m, 782m,
758w, 721s, 708s, 688s, 657s, 636s, 617s, 607s cm−1.
2
2JPU‑PT 25.2 Hz, JPU‑N 31.0 Hz 1P, PU), 35.1 (dd, 2P, PT). 15N{1H}
NMR (MeOH, 30 MHz): δ −320.2 (d, 1JNN 6 Hz, NH2), −345.3 (dd,
1
2JNP 31 Hz, JNN 6 Hz, Ru-NH2).
XBPh4. A solution of NaBPh4 (49 mg, 0.14 mmol) in methanol
(0.5 mL) was added to a solution of [RuCl(N2H4)(PP3Ph)]+Cl− in
methanol (1 mL). The precipitate formed was collected by filtration,
washed with methanol (3 × 1 mL), and dried in vacuo to afford a
yellow solid (56 mg, 48 μmol, 77%). C66H66BClN2P4Ru (1158.55)
1
requires C, 68.4; H, 5.8; N, 2.4; found C, 68.3; H, 6.0; N, 2.4%. H
NMR (THF-d8, 400 MHz): δ 7.82 (m, 4H, Ph), 7.71−7.24 (m, 22H,
Ph), 7.09−6.75 (m, 24H, Ph), 3.39−3.09 (m, 4H, RuNH2, CH2),
2.65−2.37 (m, 2H, CH2), 2.36−1.97 (m, 8H, CH2), 1.94 (br, 2H,
NH2). 1H{31P} NMR (THF-d8, 400 MHz): δ 7.82 (m, 4H, Ph), 7.53−
7.24 (m, 22H, Ph), 7.05−6.74 (m, 24H, Ph), 3.34−3.14 (m, 4H,
RuNH2, CH2), 2.57−2.42 (m, 2H, CH2), 2.27 (m, 2H, CH2), 2.13 (m,
The 15N-labeled analogue [RuCl(η2-15N2H4)(η3-PP3iPr)]+Cl− was
prepared in a similar reaction using 15N2H4. 31P{1H} NMR (MeOH/
2
2
THF/THF-d8, 122 MHz): δ 108.4 (dt, JPC‑PE 18 Hz, JPC‑PF 21 Hz,
3
2H, CH2), 2.03 (br, 4H, CH2), 1.93 (br t, JHH 4 Hz, 2H, NH2).
1P, PC), 91.9 (dd, JPE‑N 21 Hz, 2P, PT), 8.3 (d, 1P, PF). 15N{1H}
2
2
31P{1H} NMR (THF-d8, 162 MHz): δ 142.5 (dt, JPC‑PU 11.0 Hz,
NMR (MeOH/THF/THF-d8, 41 MHz): δ −336.4 (s, free 15N2H4),
2
2JPC‑PT 11.3 Hz, 1P, PC), 59.2 (dt, JPU‑PT 25.2 Hz, 1P, PU), 34.1 (dd,
2
−364.7 (d, JNP 21 Hz, Ru-NH2).
2P, PT). 15N{1H} NMR (THF-d8, 41 MHz, from HN-HSQC): δ
[RuCl(η2-NH2NHPh)(η3-PP3 iPr)]+Cl− (2). Methanol (6 drops) was
added to a suspension of [RuCl(PP3iPr)]+Cl− (0.113 g, 0.177 mmol)
and phenylhydrazine (0.307 g, 2.84 mmol) in THF (1 mL) under
nitrogen to give a dark orange solution. Hexane (10 mL) was added
and yellow solid precipitated from the reaction mixture overnight. The
product was collected by filtration, washed with hexane, then dried in
vacuo (0.146 g, 0.157 mmol, 89%). C30H62Cl2N2P4Ru·C6H8N2·C4H8O
(927.07) requires C, 51.8; H, 8.5; N, 6.0; found C, 51.4; H, 8.5; N,
6.3%. 31P{1H} NMR (phenylhydrazine/THF/THF-d8, 162 MHz): δ
104.8 (m, 1P, PC), 83.9 (br, 1P, PT1), 72.3 (br, 1P, PT2), 8.4 (m, 1P,
PF). 31P solid state NMR: δ 105.1 (1P, PC), 72.1 (1P, PT1), 68.1 (1P,
PT2), 3.9 (1P, PF).
1
1
−321.1 (corr with H δ 1.94, NH2), −344.8 (corr with H δ 3.26,
RuNH2). IR: 3343w, 3296m, 3254w, 3231w, 3053m, 1600w, 1579m,
1482m, 1435s, 1337w, 1306w, 1264w, 1190w, 1160w, 1097m, 1031w,
999w, 972w, 917w, 899w, 885w, 847w, 830w, 801w, 788w, 735s, 720s,
701s, 674m, 612s cm−1.
[RuCl(NH2NHPh)(PP3Ph)]+X− (6). XCl. Phenylhydrazine (0.1
mL, 1 mmol) was added to a suspension of [RuCl2(PP3Ph)] (32 mg,
38 μmol) in THF (0.6 mL) under nitrogen to give a pale yellow
solution. Diethyl ether (2 mL) was added and the reaction mixture left
to stand for 1 week. Crystals suitable for X-ray crystallography were
obtained from this reaction mixture. The remaining solid was collected
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Inorganic Chemistry
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by filtration, washed with diethyl ether (3 × 1 mL), and dried in vacuo
(30 mg, 32 μmol, 83%). 31P solid state NMR: δ 140.4 (1P, PC), 59.4
(1P, PU), 37.0 (d, JP−P 283 Hz, 1P, PT1), 30.4 (d, JP−P 283 Hz, 1P,
PT2).
a dark green then yellow reaction mixture which was filtered into an
1
NMR tube. H NMR (THF-d8, 400 MHz, high field only): δ −9.49
(br, RuH2). 31P{1H} NMR (THF-d8, 162 MHz): δ 162.1 (m, RuN2
PC), 155.0 (q, 2JPC‑PE 12 Hz, RuH2 PC), 92.1 (br, RuH2 PT), 88.3 (m,
RuN2 PT). 15N{1H} NMR (THF-d8, 41 MHz): δ −12.8 (s, Nβ), −53.3
(m, RuNα).
2
2
XBPh4. A solution of NaBPh4 (37 mg, 0.11 mmol) in methanol
(0.5 mL) was added to a solution of [RuCl(NH2NHPh)(PP3Ph)]+Cl−
(37 mg, 39 μmol) in methanol (0.5 mL). The precipitate formed was
collected by filtration, washed with methanol (2 × 3 mL), and dried in
vacuo to afford a yellow solid (39 mg, 32 μmol, 81%).
C72H70BClN2P4Ru (1234.65) requires C, 70.0; H, 5.7; N, 2.3; found
C, 70.0; H, 5.8; N, 2.3%. 1H NMR (THF-d8, 400 MHz, 281K): δ 7.72
(br, 4H, Ph), 7.53 (m, 4H, Ph), 7.44 (m, 12H, Ph), 7.15−6.74 (m,
32H, Ph), 6.64 (m, 1H, Ph), 5.44 (m, 2H, Ph), 3.70 (br, 3H, RuNH2
and NHPh), 3.22 (m, 2H, CH2), 2.60 (m, 2H, CH2), 2.27−1.94 (m,
8H, CH2). 1H{31P} NMR (THF-d8, 400 MHz, 280K): δ 7.72 (br, 4H,
Ph), 7.53 (m, 4H, Ph), 7.44 (m, 12H, Ph), 7.15−6.74 (m, 32H, Ph),
6.64 (m, 1H, Ph), 5.44 (m, 2H, Ph), 3.70 (br, 3H, RuNH2 and
NHPh), 3.22 (m, 2H, CH2), 2.60 (m, 2H, CH2), 2.20 (m, 2H, CH2),
2.14−1.90 (m, 6H, CH2). 31P{1H} NMR (THF-d8, 162 MHz, 280 K):
[RuH2(PP3iPr)] (8). A condenser containing dry ice and acetone was
attached to a flask containing [RuCl(PP3iPr)]+Cl− (0.393 g, 0.615
mmol) and sodium (0.29 g, 13 mmol) under argon. Ammonia
(approximately 50 mL) was condensed into the flask, and the mixture
refluxed for about 4 h. The ammonia was slowly evaporated off under a
stream of argon. The residue was dried in vacuo to remove the last
traces of ammonia then extracted with pentane (50 mL) and filtered
through Celite, and the solvent was removed under reduced pressure.
The residue was dried in vacuo to afford a pale brown solid (0.129 g,
0.201 mmol, 33% yield). C24H56P4Ru·C5H12 (641.82) requires C, 54.3;
H, 10.7; found C, 54.5; H, 10.3%. 1H NMR (benzene-d6, 400 MHz): δ
1.68 (m, 6H, CH), 1.47−1.32 (br m, 12H, CH2), 1.27 (m, 18H, CH3),
1
1.20 (m, 18H, CH3), −9.13 (br, 2H, RuH). H{31P} NMR (benzene-
3
2
d6, 400 MHz): δ 1.68 (sep, JHH 7 Hz, 6H, CH), 1.36 (br m, 12H,
δ 139.8 (app. q, splitting 12 Hz, 1P, PC), 59.0 (dt, JPU‑PT 26 Hz,
CH2), 1.27 (d, 3JHH 7 Hz, 18H, CH3), 1.20 (d, 3JHH 7 Hz, 18H, CH3),
−9.13 (br, 2H, RuH). 31P{1H} NMR (benzene-d6, 162 MHz): δ 154.2
(q, 2JPC‑PE 12 Hz, 1P, PC), 91.8 (br, 3P, PE). 1H NMR (toluene-d8, 600
MHz, 200 K): δ 2.23−0.53 (CH/CH2/CH3), −5.55 (m, 1H, RuH),
−12.61 (m, 1H, RuH). 31P{1H} NMR (toluene-d8, 243 MHz, 200 K):
δ 152.6 (br, 1P, PC), 95.5 (br, 2P, PT), 79.0 (br, 1P, PU). Crystals
suitable for X-ray crystallography were obtained by slow evaporation of
a benzene/benzene-d6 solution under argon.
2JPU‑PC 12 Hz, 1P, PU), 32.4 (dd, 2JPU‑PT 26 Hz, 2JPT‑PC 11 Hz, 2P, PT).
15N{1H} NMR (THF-d8, 41 MHz, from HN-HSQC, 284K): δ
1
1
−284.8, (corr with H δ 3.70, NHPh), −328.4 (corr with H δ 3.70,
RuNH2). IR: 3342w, 3276m, 3191w, 3053s, 1952w, 1889w, 1818w,
1770w, 1601m, 1579m, 1495m, 1483s, 1435s, 1337w, 1308w, 1251m,
1190w, 1159w, 1098m, 1031w, 999w, 971w, 897w, 885w, 847m, 829w,
801w, 787w, 748s, 734s, 720s, 701s, 676m, 623m, 612s cm−1.
[RuCl(NH2NHMe)(PP3Ph)]+X− (7). X = Cl. Methylhydrazine (0.1
mL, 2 mmol) was added to a suspension of [RuCl2(PP3Ph)] (44 mg,
52 μmol) in THF (0.4 mL) under nitrogen to give a very pale yellow
solution. Diethyl ether (2 mL) was added, and the reaction mixture
was left to stand for 1 month. The pale yellow needles formed were
collected by filtration, washed with diethyl ether (3 × 0.5 mL), and
dried in vacuo (44 mg, 50 μmol, 95%). C43H48Cl2N2P4Ru (888.78)
requires C, 58.1; H, 5.5; N, 3.2; found C, 58.3; H, 5.4; N, 3.1%.
[RuH2(PP3iPr)] was also synthesized by treatment of [RuCl-
(PP3iPr)]+Cl− (0.302 g, 0.473 mmol) with KBEt3H (0.187 g, 1.36
mmol) in toluene (10 mL) under argon overnight. The solvent was
removed under reduced pressure with warming from an oil bath. The
residue was extracted with hexane (50 mL), sonicated for 20 min,
filtered through Celite and the solvent removed under reduced
pressure. The residue was dried in vacuo to afford a very pale yellow
solid (0.107 g, 0.187 mmol, 40% yield).
2
31P{1H} NMR (MeOH, 122 MHz): δ 144.9 (dt, JPC‑PU 11.1 Hz,
[RuH(C6H4NNH)(η3-PP3iPr)] (9). [RuCl(η2-NH2NHPh)(η3-
PP3iPr)]+Cl− (90 mg, 0.12 mmol) and KOtBu (83 mg, 0.74 mmol)
were stirred overnight in THF (2 mL) under nitrogen to give a dark
blue-green suspension which gradually turned orange. The reaction
mixture was evaporated to dryness under vacuum. The residue was
extracted with pentane (15 mL) and filtered through Celite, and the
solvent was removed under reduced pressure. The residue was dried in
vacuo to afford a red-orange solid (30 mg, 45 μmol, 37%).
C30H60N2P4Ru (673.87) requires C, 53.5; H, 9.0; N, 4.2 found C,
53.8; H, 9.0; N, 4.0%. 1H NMR (THF-d8, 300 MHz): δ 14.75 (s, 1H,
NH), 8.08 (m, 1H, Ph), 8.01 (m, 1H, Ph), 6.83 (m, 1H, Ph), 6.71 (m,
1H, Ph), 2.23−1.92 (m, 6H, CH/CH2), 1.90−1.61 (m, 7H, CH/
CH2), 1.47 (m, 2H, CH2), 1.32−1.08 (m, 20H, CH2/CH3), 1.08−0.95
(m, 7H, CH2/CH3), 0.77 (m, 6H, CH3), −0.02 (m, 6H, CH3), −12.52
2
2JPC‑PT 10.9 Hz, 1P, PC), 60.2 (dt, JPU‑PT 25.2 Hz, 1P, PU), 35.1 (dd,
2P, PT). IR: 3302w, 3277w, 3193w, 3047w, 3034w, 1572w, 1482s,
1433s, 1334w, 1313w, 1274w, 1191m, 1157w, 1122m, 1098s, 1065m,
1030w, 998m, 973w, 959w, 897m, 847w, 828s, 801m, 787m, 756m,
745s, 719s, 698s, 669m cm−1. Crystals suitable for X-ray crystallog-
raphy were obtained from a similar reaction mixture to that described
above.
X = BPh4. A solution of NaBPh4 (46 mg, 0.13 mmol) in methanol
(1 mL) was added to a solution of [RuCl(NH2NHMe)(PP3Ph)]+Cl−
(53 mg, 60 μmol) in methanol (1 mL). The precipitate formed was
collected by filtration, washed with methanol several times, and dried
in vacuo to afford a pale yellow solid (64 mg, 55 μmol, 91%). 1H NMR
(THF-d8, 400 MHz): δ 7.75 (br, 4H, Ph), 7.54 (m, 4H, Ph), 7.46−
7.26 (m, 18H, Ph), 7.03 (m, 2H, Ph), 7.00−6.86 (m, 14H, Ph), 6.82
(m, 8H, Ph), 3.21 (m, 2H, CH2), 3.04 (br s, 2H, RuNH2), 2.48 (m,
2H, CH2), 2.19 (m, 2H, CH2), 2.04 (m, 6H, CH2), 1.50 (q, 3JHH 6 Hz,
2
(dt, JHP 14 Hz, 28 Hz, 1H, RuH). 1H{31P} NMR (THF-d8, 300
MHz): δ 14.74 (s, 1H, NH), 8.08 (m, 1H, Ph), 8.01 (m, 1H, Ph), 6.83
(m, 1H, Ph), 6.71 (m, 1H, Ph), 2.22−1.94 (m, 6H, CH/CH2), 1.89−
1.60 (m, 7H, CH/CH2), 1.47 (m, 2H, CH2), 1.31−1.08 (m, 20H,
3
1
1H, NHMe), 0.80 (d, JHH 6 Hz, 3H, CH3). H{31P} NMR (THF-d8,
400 MHz): δ 7.75 (br, 4H, Ph), 7.54 (m, 4H, Ph), 7.46−7.25 (m,
18H, Ph), 7.03 (m, 2H, Ph), 7.00−6.86 (m, 14H, Ph), 6.82 (m, 8H,
Ph), 3.21 (m, 2H, CH2), 3.04 (m, 2H, RuNH2), 2.47 (m, 2H, CH2),
3
CH2/CH3), 1.08−0.97 (m, 7H, CH2/CH3), 0.77 (d, JHH 7 Hz, 6H,
CH3), −0.02 (d, 3JHH 7 Hz, 6H, CH3), −12.52 (s, 1H, RuH). 31P{1H}
2
2
NMR (THF-d8, 122 MHz): δ 103.4 (dt, JPC‑PE 15 Hz, JPC‑PF 19 Hz,
3
1P, PC), 92.5 (d, 2P, PT), 8.2 (d, 1P, PF). 15N{1H} NMR (THF-d8, 30
MHz, from HN-HSQC): δ 2.4 (corr with H δ 14.75, RuNH). IR:
2.19 (m, 2H, CH2), 2.04 (m, 6H, CH2), 1.50 (q, JHH 6 Hz, 1H,
NHMe), 0.80 (d, 3JHH 6 Hz, 3H, CH3). 31P{1H} NMR (THF-d8, 162
1
2
MHz): δ 140.5 (app. q, splitting 12 Hz, 1P, PC), 57.6 (dt, JPU‑PT 25
3162m, 1928m (ν Ru−H), 1602w, 1574m, 1537w, 1412m, 1364m,
1307s, 1292s, 1238s, 1170m, 1152w, 1095w, 1076w, 1035w, 1020m,
1008m, 923w, 881m, 860m, 835w, 794w, 774m, 751w, 720s, 707s,
695s, 672s, 646s, 625s, 611s, 601s cm−1. MS (ESI, THF): m/z
675.2836 [100%, (M + H)+]. Crystals suitable for X-ray crystallog-
raphy were obtained by slow evaporation of a toluene solution under
nitrogen.
Hz, 2JPU‑PC 12 Hz, 1P, PU), 33.4 (dd, 2JPU‑PT 25 Hz, 2JPT‑PC 12 Hz, 2P,
PT). 15N{1H} NMR (THF-d8, 41 MHz, from HN-HSQC): δ −309.6
(corr with 1H δ 1.50, NHMe), −314.5 (corr with 1H δ 3.04, RuNH2).
IR: 3319w, 3271w, 3189w, 3053m, 3035m, 1579m, 1483s, 1435s,
1337w, 1310w, 1269w, 1247w, 1191w, 1160w, 1125w, 1098m, 1031w,
1000w, 972w, 948w, 899w, 885w, 847w, 830m, 819w, 802w, 788w,
734s, 701s, 674m, 658w, 612m cm−1.
The 15N-labeled analogue was prepared in a similar manner using
[RuCl(NH215NHPh)(PP3iPr)]+Cl− (72 mg, 96 μmol) and KOtBu (42
mg, 0.37 mmol) to afford [RuH(C6H415NNH)(η3-PP3iPr)] (39 mg,
58 μmol, 60%). 15N NMR (THF-d8, 41 MHz): δ 110.7 (NC6H4).
Reaction of [RuCl(η2-15N2H4)(η3-PP3 iPr)]+Cl− with KOtBu.
[RuCl(η2-15N2H4)(η3-PP3iPr)]+Cl− (29 mg, 43 μmol) and KOtBu
(22 mg, 0.20 mmol) were suspended in THF-d8 under nitrogen to give
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Inorganic Chemistry
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[RuH(NHNCH2)(PP3iPr)] (10). [RuCl(η2-NH2NHMe)(η3-
PP3iPr)]+Cl− (60 mg, 88 μmol) and KOtBu (80 mg, 0.71 mmol)
were stirred in THF (2 mL) under nitrogen for 6 min, then the
reaction mixture was evaporated to dryness under reduced pressure.
The residue was extracted with pentane (12 mL), filtered through
Celite, and the solvent was removed under reduced pressure. The
residue was dried in vacuo to afford a yellow solid (33.6 mg, 54.9 μmol,
ACKNOWLEDGMENTS
■
We thank the Australian Research Council and the University
of New South Wales for funding. We also thank Dr. James
Hook and Dr. Aditya Rawal at the Mark Wainwright Analytical
Centre (University of New South Wales) for assistance in
obtaining the 31P solid state NMR spectra and Dr. Alison
Magill for assistance in analyzing the inversion transfer recovery
data for compound 10.
1
2
62%). H NMR (toluene-d8, 600 MHz): δ 6.28 (d, JHH 13.5 Hz, 1H,
2
2
CHH), 5.54 (d, JHH 13.5 Hz, 1H, CHH), 5.27 (d, JHP 7.1 Hz,
2
1H, NH), 2.21−0.61 (m, CH/CH2/CH3), −10.69 (ddt, JHP 93.5,
29.8, 18.1 Hz, 1H, RuH). H{31P} NMR (toluene-d8, 600 MHz): δ
1
REFERENCES
2
2
■
6.28 (d, JHH 13.5 Hz, 1H, CHH), 5.54 (d, JHH 13.5 Hz, 1H, 
CHH), 5.27 (s, 1H, NH), 2.21−0.61 (m, CH/CH2/CH3), −10.69 (s,
1H, RuH). 31P{1H} NMR (toluene-d8, 243 MHz): δ 145.4 (app. q,
splitting =11.3 Hz, 1P, PC), 63.5 (app. t, splitting =13.3 Hz, 2P, PT),
52.9 (m, 1P, PU). 13C{1H} NMR (toluene-d8, 151 MHz, from HC-
(1) Lukoyanov, D.; Dikanov, S. A.; Yang, Z.-Y.; Barney, B. M.;
Samoilova, R. I.; Narasimhulu, K. V.; Dean, D. R.; Seefeldt, L. C.;
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Am. Chem. Soc. 2009, 131, 10358. Saouma, C. T.; Moore, C. E.;
Rheingold, A. L.; Peters, J. C. Inorg. Chem. 2011, 50, 11285. Crossland,
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(3) Chen, Y.; Zhou, Y.; Chen, P.; Tao, Y.; Li, Y.; Qu, J. J. Am. Chem.
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(4) Yuki, M.; Miyake, Y.; Nishibayashi, Y. Organometallics 2012, 31,
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(6) Heaton, B. T.; Jacob, C.; Page, P. Coord. Chem. Rev. 1996, 154,
193.
1
1
HSQC): δ 104.4 (corr with H δ 6.28 and 5.54, NCH2). H NMR
2
(toluene-d8, 600 MHz, 200 K): δ 6.55 (d, JHH 13 Hz, 1H, CHH),
5.87 (d, 2JHH 13 Hz, 1H, CHH), 5.51 (br, 1H, NH), 2.35−0.00 (m,
CH/CH2/CH3), −10.61 (m, 1H, RuH). 15N{1H} NMR (toluene-d8,
1
61 MHz, from HN-HSQC, 200 K): δ −266.4 (corr with H δ 5.51,
RuNH).
Reaction of [RuCl(15N2H4)(PP3 Ph)]+Cl− with KOtBu. [RuCl-
(15N2H4)(PP3Ph)]+Cl− (48 mg, 55 μmol) and KOtBu (15 mg, 0.13
mmol) were suspended in THF-d8 under nitrogen to give a dark red
solution and some insoluble orange solid. The supernatant liquid was
decanted into an NMR tube. 1H NMR (THF-d8, 400 MHz, high field
only): δ −7.18 (m, RuH2). 31P{1H} NMR (THF-d8, 162 MHz): δ
160.5 (m, RuN2 PC), 158.0 (q, 2JPC‑PE 7 Hz, RuH2 PC), 77.9 (d, RuH2
PE), 70.5 (m, RuN2 PE). 15N{1H} NMR (THF-d8, 41 MHz): δ −24.7
(s, Nβ), −63.4 (m, RuNα).
(7) Field, L. D.; Li, H. L.; Dalgarno, S. J.; McIntosh, R. D. Inorg.
Chem. 2012, 51, 3733 and references therein..
Reaction of [RuCl(NH2NHPh)(PP3 Ph)]+Cl− with KOtBu. [RuCl-
(NH2NHPh)(PP3Ph)]+Cl− (25 mg, 26 μmol) and KOtBu (18 mg, 0.16
mmol) were suspended in THF (0.4 mL) and THF-d8 (0.15 mL)
under argon to give a dark green suspension which on standing turned
dark orange-red with some insoluble dark brown solid. 1H NMR
(THF/THF-d8, 400 MHz): δ 7.26 (s, C6H6). 31P{1H} NMR (THF/
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2
THF-d8, 162 MHz): δ 160.2 (q, JPC‑PE 24 Hz, RuN2 PC), 70.1 (d,
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RuN2 PE).
Reaction of [RuCl(NH2NHMe)(PP3 Ph)]+Cl− with KOtBu. [RuCl-
(NH2NHMe)(PP3Ph)]+Cl− (17 mg, 19 μmol) and KOtBu (19 mg,
0.17 mmol) were suspended in THF (0.4 mL) and THF-d8 (0.15 mL)
under argon to give an orange solution and some insoluble orange
1
solid. H NMR (THF/THF-d8, 300 MHz): δ 0.15 (s, CH4). 31P{1H}
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2
NMR (THF/THF-d8, 122 MHz): δ 160.2 (q, JPC‑PE 24 Hz, RuN2
PC), 70.1 (d, RuN2 PE). IR (orange solid): 2080s (ν(NN), RuN2)
cm−1.
ASSOCIATED CONTENT
■
S
* Supporting Information
CIF files for 1, 3, 5, 6, 7, 8, and 9. Figures for 31P{1H} NMR
spectrum of 3; H and 31P{1H} NMR spectra of 10; details of
1
inversion transfer recovery NMR experiments. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: l.field@unsw.edu.au.
Author Contributions
The manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript. Dr. Scott J. Dalgarno and Dr. Ruaraidh D.
McIntosh were primarily responsible for the X-ray crystallo-
graphic analysis.
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Notes
The authors declare no competing financial interest.
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