Preparation and reactivity of half-sandwich hydrazine complexes of ruthenium and osmium

Article abstract of DOI:10.1016/j.jorganchem.2011.09.011

Hydrazine complexes [MCl(η⁶-p-cymene)(RNHNH ₂)L]BPh₄ (1-6) [M = Ru, Os; R = H, Me, Ph; L = P(OEt) ₃, PPh(OEt)₂, PPh₂OEt] were prepared by allowing dichloro complexes MCl₂(η⁶-p-cymene)L to react with hydrazines RNHNH₂ in the presence of NaBPh₄. Treatment of ruthenium complexes [RuCl(η⁶-p-cymene)(RNHNH ₂)L]BPh₄ with Pb(OAc)₄ led to acetate complex [Ru(κ²-O₂CCH₃)(η⁶-p- cymene)L]BPh₄ (7). Instead, the reaction of osmium derivatives [OsCl(η⁶-p-cymene)(CH₃NHNH₂)L]BPh ₄ with Pb(OAc)₄ afforded the methyldiazenido complex [Os(CH₃N₂)(η⁶-p-cymene)L}]BPh₄ (8). Treatment with HCl of this diazenido complex 8 led to the methyldiazene cation [OsCl(CH₃NNH)(η⁶-p-cymene)L}]⁺ (9⁺). The complexes were characterised spectroscopically and by X-ray crystal structure determination of [OsCl(η⁶-p-cymene) (PhNHNH₂){PPh(OEt)₂}]BPh₄ (6b) and [Ru(κ²-O₂CCH₃)(η⁶-p- cymene){PPh(OEt)₂}]BPh₄ (7b).

Full text of DOI:10.1016/j.jorganchem.2011.09.011

Journal of Organometallic Chemistry 697 (2012) 6e14
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Preparation and reactivity of half-sandwich hydrazine complexes of ruthenium
and osmium
,
a
b
Gabriele Albertin a , Stefano Antoniutti , Jesús Castro
*
a Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia, Italy
b Departamento de Química Inorgánica, Universidade de Vigo, Facultade de Química, Edificio de Ciencias Experimentais, 36310 Vigo (Galicia), Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Hydrazine complexes [MCl(
h
6-p-cymene)(RNHNH2)L]BPh4 (1e6) [M
¼
Ru, Os;
R
h
¼
H, Me, Ph;
L ¼ P(OEt)3, PPh(OEt)2, PPh2OEt] were prepared by allowing dichloro complexes MCl2(
react with hydrazines RNHNH2 in the presence of NaBPh4. Treatment of ruthenium complexes [RuCl(h6
p-cymene)(RNHNH2)L]BPh4 with Pb(OAc)4 led to acetate complex [Ru(k2eO2CCH3)( 6-p-cymene)L]BPh4
(7). Instead, the reaction of osmium derivatives [OsCl(
6-p-cymene)(CH3NHNH2)L]BPh4 with Pb(OAc)4
afforded the methyldiazenido complex [Os(CH3N2)(
6-p-cymene)L}]BPh4 (8). Treatment with HCl of this
diazenido complex 8 led to the methyldiazene cation [OsCl(CH3N]NH)(
6-p-cymene)L}]þ (9þ). The
complexes were characterised spectroscopically and by X-ray crystal structure determination of
[OsCl(
6-p-cymene)(PhNHNH2){PPh(OEt)2}]BPh4 (6b) and [Ru(k2eO2CCH3)( 6-p-cymene){PPh(OEt)2}]
BPh4 (7b).
6-p-cymene)L to
Received 25 July 2011
Received in revised form
8 September 2011
-
h
Accepted 17 September 2011
h
h
Keywords:
Hydrazine
Diazo compounds
Half-sandwich complexes
Ruthenium
h
h
h
Ó 2011 Elsevier B.V. All rights reserved.
Osmium
1. Introduction
iron triad stabilised by phosphite, carbonyl or tris(pyrazolyl)borate
ligands, of the type [MH(RNHNH2)L4]þ, [M(RNHNH2)2L4]2þ
,
The chemistry of transition metal complexes containing
hydrazine NH2NH2 or substituted hydrazine RNHNH2 as ligands
continues to be studied, not only due to interest in the differing
coordination modes and interesting reactivity shown by these
ligands [1e4], but also due to the relationship of hydrazine with the
nitrogen fixation process [5e7].
[M(CO)(RNHNH2)L4]2þ, [M(Tp)(RNHNH2)L(PPh3)]þ [M ¼ Fe, Ru, Os;
Tp ¼ tris(pyrazolyl)borate; L ¼ P(OEt)3, PPh(OEt)2] [11].
We have now extended these studies with the aim of intro-
ducing the arene ligands into the diazo chemistry of the iron triad.
In this paper, we report the synthesis and reactivity of new
hydrazine complexes of ruthenium and osmium stabilised by the p-
cymene ligand.
Hydrazine is reported to coordinate both
h
1- and
h
2- to a metal
centre, and may also behave as a bridging
me
h2 ligand [1e4].
Coordinated NH2NH2 can either give stable 1,2-diazene complexes
[M]eNH]NH, by both oxidation [5] and deprotonation with
a strong base [4], or undergo reduction to ammonia [5b,6,7a,8].
Hydrazine has also been shown to be a substrate of nitrogenase and
has been trapped as an intermediate during enzyme turnover [9].
A number of hydrazine RNHNH2 complexes of several transition
2. Experimental section
2.1. General comments
All synthetic work was carried out in an appropriate atmosphere
(Ar, N2) using standard Schlenk techniques or a vacuum atmo-
sphere dry-box. Once isolated, the complexes were found to be
relatively stable in air, but were stored in an inert atmosphere
at ꢀ25 ꢁC. All solvents were dried over appropriate drying agents,
degassed on a vacuum line, and distilled into vacuum-tight storage
flasks. RuCl3$3H2O and OsO4 were Pressure Chemical Co. (USA)
products, used as received. Phosphites PPh(OEt)2 and PPh2OEt were
prepared by the method of Rabinowitz and Pellon [12]. Instead,
P(OEt)3 (Aldrich) was used as received. Hydrazine NH2NH2 was
prepared by decomposition of hydrazine cyanurate (Fluka)
following the reported method [13]. High-grade (99.99%) lead(IV)
acetate was purchased from Aldrich. Other reagents were
metals have been reported in the past 30 years, mainly with
p-
acceptors such as carbonyl, phosphine and cyclopentadienyl as
ancillary ligands [1e4]. Less attention has been devoted to arene
ligands and, for the iron triad, only a few examples of hydrazine
complexes containing arene as supporting ligand have been re-
ported [10].
We are interested in the chemistry of diazo complexes and have
reported the synthesis and reactivity of hydrazine complexes of the
* Corresponding author. Fax: þ39 0 41 234 8917.
E-mail address: albertin@unive.it (G. Albertin).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.09.011

G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
7
purchased from commercial sources in the highest available purity
and used as received. Infrared spectra were recorded on Per-
kineElmer Spectrum One FTeIR spectrophotometer. NMR spectra
(1H, 31P, 13C) were obtained on AC200 or AVANCE 300 Bruker
spectrometers at temperatures between ꢀ80 and þ30 ꢁC, unless
otherwise noted. 1H and 13C spectra are referenced to internal
tetramethylsilane; 31P{1H} chemical shifts are reported with
respect to 85% H3PO4, with downfield shifts considered positive.
The COSY, HMQC and HMBC NMR experiments were performed
using their standard programs. The iNMR software package [14]
was used to treat NMR data. The conductivity of 10ꢀ3 mol dmꢀ3
solutions of the complexes in CH3NO2 at 25 ꢁC were measured with
a Radiometer CDM 83. Elemental analyses were determined in the
Microanalytical Laboratory of the Dipartimento di Scienze Farm-
aceutiche of the University of Padua, Italy.
JAB ¼ 6.3), 5.28 (d, 1H, HB p-cym), 4.02, 3.90 (m, 4H, CH2), 3.60, 3.51
(m, br, 2H, MeNH2), 2.63 (m, br, 2H, NeNH2), 2.57 (m, 1H, CH iPr),
1.90 (s, 3H, CH3 p-cym), 1.36 (t, 6H, CH3 phos), 1.15, 1.13 (d, 6H, CH3
iPr) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 144.0 (s) ppm.
L
¼ 55.1 Uꢀ1 molꢀ1 cm2. C44H53BClN2O2PRu (820.21): C 64.43, H
M
6.51, N 3.42, Cl 4.32; found C 64.20, H 6.39, N 3.28, Cl 4.56%.
1c: IR (KBr pellet): nNH ¼ 3334, 3289, 3255 (m) cmꢀ1. 1H NMR
(CD2Cl2, 25 ꢁC):
d
¼ 7.82e6.85 (m, 30H, Ph), 5.46 (d, 1H, HC p-cym,
JCD ¼ 6.1 Hz), 5.43 (d, 1H, HD p-cym), 5.37 (d, 1H, HA p-cym,
JAB ¼ 6.1), 5.31 (d, 1H, HB p-cym), 3.82e3.50 (m, 2H, CH2), 3.58, 3.51
(m, br, 2H, MeNH2), 2.67 (br, 2H, NeNH2), 2.63 (m, 1H, CH iPr), 2.00
(s, 3H, CH3 p-cym), 1.20 (t, 3H, CH3 phos, JHH ¼ 7.0), 1.17, 1.10 (d, 6H,
CH3 iPr, JHH
d
¼
6.9) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
¼ 128.1 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 165e122 (m,
Ph),112.86 (d, br, C1 p-cym), 102.01 (d, br, C4 p-cym), 93.73 (d, C6 p-
cym, JCP ¼ 5.8), 89.10 (d, C2 p-cym, JCP ¼ 5.5), 88.42 (d, br, C3 p-cym),
88.15 (d, br, C5 p-cym), 66.04 (d, CH2, JCP ¼ 13.9), 30.96 (s, CH iPr),
22.76, 21.75 (s, CH3 iPr), 18.16 (s, CH3 p-cym), 16.24 (d, CH3 phos,
2.2. Synthesis of complexes
JCP ¼ 6.7) ppm. L ¼ 49.6 Uꢀ1 molꢀ1 cm2. C48H53BClN2OPRu
Compounds RuCl2(h h
6-p-cymene)L and OsCl2( 6-p-cymene)L
M
(852.25): C 67.65, H 6.27, N 3.29, Cl 4.16; found C 67.42, H 6.15, N
3.17, Cl 4.33%.
[L ¼ P(OEt)3, PPh(OEt)2, PPh2OEt] were prepared following the
methods previously reported [15,16].
2a: IR (KBr pellet): nNH ¼ 3295, 3261 (m) cmꢀ1. 1H NMR (CD2Cl2,
25 ꢁC):
d
¼ 7.34e6.87 (m, 20H, BPh4), 5.60 (d, 1H, HA p-cym,
2.2.1. [RuCl(
h
6-p-cymene)(RNHNH2)L]BPh4 (1e3) [R ¼ H (1), Me
JAB ¼ 6.3 Hz), 5.58 (d, 1H, HB p-cym), 5.51 (d, 1H, HC p-cym,
JCD ¼ 6.1), 5.27 (d, 1H, HD p-cym), 4.55 (dm, br, 2H, NH2), 4.29 (m,
1H, NH), 4.15 (m, 6H, CH2), 2.71 (m, 1H, CH iPr), 2.52 (d, 3H, NeCH3,
JHH ¼ 6.2), 2.07 (s, 3H, CH3 p-cym), 1.35 (t, 9H, CH3 phos), 1.23, 1.21
(d, 6H, CH3 iPr) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
(2), Ph (3); L ¼ P(OEt)3 (a), PPh(OEt)2 (b), PPh2OEt (c)]
In a 25-mL three-necked round-bottomed flask were placed
0.30 mmol of the appropriate RuCl2(h
6-p-cymene)L complex, an
excess of NaBPh4 (0.60 mmol, 0.20 g), 3 mL of ethanol and 5 mL of
dichloromethane. A slight excess of the appropriate hydrazine
RNHNH2 (0.31 mmol) was added to the resulting solution cooled
to ꢀ196 ꢁC. The reaction mixture was left to reach room tempera-
ture, stirred for 5 h and then the solvent was removed under
reduced pressure to give an oil which was triturated with ethanol
(3 mL). By cooling to ꢀ25 ꢁC of the resulting solution, a yellow solid
slowly separated out, which was filtered and crystallised from
ethanol. Yield: 154 mg (65%) for 1a, 187 mg (76%) for 1b, 202 mg
(79%) for 1c, 166 mg (69%) for 2a, 193 mg (77%) for 2b, 216 mg (83%)
for 2c, 181 mg (70%) for 3a, 228 mg (85%) for 3b.
d
¼ 114.9 (s) ppm. L ¼ 51.8 Uꢀ1 molꢀ1 cm2. C41H55BClN2O3PRu
M
(802.19): C 61.39, H 6.91, N 3.49, Cl 4.42; found C 61.18, H 7.03, N
3.36, Cl 4.22%.
2b: IR (KBr pellet): nNH ¼ 3389, 3261 (m) cmꢀ1. 1H NMR (CD2Cl2,
25 ꢁC):
d
¼ 7.59e6.86 (m, 25H, Ph), 5.53 (d, 1H, HC p-cym,
JCD ¼ 6.1 Hz), 5.41 (d, 1H, HA p-cym), 5.33 (d, 1H, HB p-cym,
JAB ¼ 6.4), 5.30 (d, 1H, HD p-cym), 4.18e3.95 (m, 4H, CH2), 4.15, 3.71
(d, br, 2H, NH2), 3.59 (m, 1H, NH), 2.61 (m, 1H, CH iPr), 2.33 (d, 3H,
NeCH3, JHH ¼ 6.0 Hz), 1.94 (s, 3H, CH3 p-cym), 1.41, 1.39 (t, 6H, CH3
phos), 1.18, 1.16 (d, 6H, CH3 iPr) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
1a: IR (KBr pellet): nNH ¼ 3336, 3300, 3255 (m) cmꢀ1. 1H NMR
d
¼ 144.8 (s) ppm. L ¼ 54.4 Uꢀ1 molꢀ1 cm2. C45H55BClN2O2PRu
(CD2Cl2, 25 ꢁC) see Chart 1:
d
¼ 7.48e6.86 (m, 20H, BPh4), 5.52 (d,
M
(834.24): C 64.79, H 6.65, N 3.36, Cl 4.25; found C 64.61, H 6.49, N
3.18, Cl 4.42%.
1H, HA p-cym, JAB ¼ 6.3 Hz), 5.49 (d, 1H, HC p-cym, JCD ¼ 6.2), 5.35
(d, 1H, HD p-cym), 5.18 (d, 1H, HB p-cym), 4.11 (m, 6H, CH2), 3.82,
2c: IR (KBr pellet): nNH ¼ 3285, 3261 (m) cmꢀ1. 1H NMR (CD2Cl2,
i
3.75 (br, 2H, MeNH2), 2.73 (br, 2H, NeNH2), 2.69 (m, 1H, CH Pr),
25 ꢁC):
d
¼ 7.69e6.85 (m, 30H, Ph), 5.61 (d, 2H, HC, HD p-cym,
2.06 (s, 3H, CH3 p-cym), 1.33 (t, 9H, CH3 phos, JHH ¼ 7.0), 1.21 (d, 6H,
CH3 iPr, JHH
d
¼
6.9) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
JCD ¼ 5.8 Hz), 5.48 (d, 1H, HA p-cym, JAB ¼ 5.8), 5.39 (d, 1H, HB p-
cym), 4.02 (dm, 2H, NH2), 3.84, 3.61 (m, 2H, CH2), 3.47 (m, br, 1H,
NH), 2.68 (m, 1H, CH iPr), 2.20 (d, 3H, NeCH3, JHH ¼ 6.3), 2.06 (s, 3H,
CH3 p-cym),1.24 (t, 3H, CH3 phos, JHH ¼ 7.0),1.22,1.14 (d, 6H, CH3 iPr,
¼ 115.1 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 164e122 (m,
BPh4), 114.35 (d, C1 p-cym, JCP ¼ 3.3), 104.45 (d, C4 p-cym, JCP ¼ 2.1),
92.39 (d, C5 p-cym, JCP ¼ 7.2), 89.62 (d, C2 p-cym, JCP ¼ 7.0), 87.95 (d,
br, C3 p-cym), 87.81 (d, br, C6 p-cym), 64.78 (d, CH2, JCP ¼ 3.4), 31.04
JHH ¼ 7.0) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 129.4 (s) ppm. 13
C
{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 165e122 (m, Ph),112.45 (d, C1 p-cym,
i
(s, CH Pr), 22.53, 21.97 (s, CH3 iPr), 18.59 (s, CH3 p-cym), 16.36 (d,
53.4 Uꢀ1 molꢀ1 cm2.
JCP ¼ 4.6), 103.08 (d, br, C4 p-cym), 93.60 (d, C6 p-cym, JCP ¼ 6.1),
88.76 (d, C2 p-cym, JCP ¼ 4.3), 88.41 (d, br, C5 p-cym), 87.54 (d, br, C3
p-cym), 66.22 (d, CH2, JCP ¼ 14.0), 43.46 (s, NeCH3), 31.11 (s, CH iPr),
22.76, 21.92 (s, CH3 iPr), 18.36 (s, CH3 p-cym), 16.23 (d, CH3 phos,
CH3 phos, JCP
¼
6.1) ppm.
L
¼
M
C40H53BClN2O3PRu (788.17): C 60.96, H 6.78, N 3.55, Cl 4.50; found
C 61.16, H 6.66, N 3.37, Cl 4.38%.
1b: IR (KBr pellet): nNH ¼ 3323, 3283, 3239 (m) cmꢀ1. 1H NMR
JCP ¼ 6.9) ppm. L ¼ 53.7 Uꢀ1 molꢀ1 cm2. C49H55BClN2O2PRu
(CD2Cl2, 25 ꢁC):
d
¼ 7.56e6.89 (m, 25H, Ph), 5.49 (d, 1H, HC p-cym,
M
(866.28): C 67.94, H 6.40, N 3.23, Cl 4.09; found C 67.73, H 6.28, N
3.13, Cl 4.27%.
JCD ¼ 6.2 Hz), 5.45 (d, 1H, HD p-cym), 5.30 (d, 1H, HA p-cym,
3a: IR (KBr pellet): nNH ¼ 3355, 3254 (m) cmꢀ1. 1H NMR (CD2Cl2,
25 ꢁC):
d
¼ 7.36e6.78 (m, 25H, Ph), 5.71, 5.08 (d, br, 2H, NH2), 5.62
H
4
B
H
1
A
(d, 1H, HA p-cym, JAB ¼ 6.1 Hz), 5.57 (d, 1H, HC p-cym, JCD ¼ 5.8),
5.48 (d, 1H, HB p-cym), 5.23 (d, 1H, HD p-cym), 5.38 (t, br, 1H, NH),
4.13 (m, 6H, CH2), 2.75 (m, 1H, CH iPr), 2.07 (s, 3H, CH3 p-cym), 1.27
(t, 9H, CH3 phos), 1.27, 1.26 (d, 6H, CH3 iPr) ppm. 31P{1H} NMR
3
5
2
6
CH3
H
H3C
C
CH3
(CD2Cl2, 25 ꢁC):
d
¼ 114.0 (s) ppm. L ¼ 54.0 Uꢀ1 molꢀ1 cm2.
M
H
C
H
D
C46H57BClN2O3PRu (864.26): C 63.93, H 6.65, N 3.24, Cl 4.10; found
C 63.71, H 6.56, N 3.12, Cl 4.29%.
Chart 1. Labelling scheme of the p-cymene ligand used for the NMR study.

8
G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
3b: IR (KBr pellet): nNH ¼ 3283 (m, br) cmꢀ1. 1H NMR (CD2Cl2,
C
45H55BClN2O2OsP (923.40): C 58.53, H 6.00, N 3.03, Cl 3.84; found
25 ꢁC):
d
¼ 7.84e6.56 (m, 30H, Ph), 5.77 (d, br, 1H, NH), 5.61 (d, 1H,
C 58.30, H 5.89, N 2.92, Cl 3.98%.
HA p-cym, JAB ¼ 6.1 Hz), 5.45 (d, 1H, HD p-cym, JCD ¼ 6.1), 5.43 (d,
1H, HC p-cym), 5.35 (d, 1H, HB p-cym), 5.37, 4.31 (d, br, 2H, NH2,
5c: IR (KBr pellet): nNH ¼ 3317, 3272, 3244 (m) cmꢀ1
.
1H NMR
(CD2Cl2, 25 ꢁC):
d
¼ 7.78e6.82 (m, 30H, Ph), 5.80 (d, 1H, HA p-cym,
i
JHH ¼ 8.2), 4.20e3.90 (m, 4H, CH2), 2.67 (m, 1H, CH Pr, JHH ¼ 6.8),
JAB ¼ 6.0 Hz), 5.64 (d,1H, HD p-cym, JCD ¼ 6.0), 5.63 (d, 2H, HB, HC p-
cym), 4.65 (t, br), 4.52 (m, br) (2H, NH2), 3.90e3.78, 3.59e3.47 (m,
2H, CH2), 3.31 (m, br, 1H, NH), 2.65 (m, 1H, CH iPr), 2.16 (s, 3H, CH3
p-cym), 2.14 (d, 3H, NeCH3, JHH ¼ 6.4), 1.25, 1.18 (d, 6H, CH3 iPr,
JHH ¼ 7.0), 1.22 (t, 3H, CH3 phos, JHH ¼ 7.1) ppm. 31P{1H} NMR
1.96 (s, 3H, CH3 p-cym), 1.38, 1.36 (t, 6H, CH3 phos, JHH ¼ 7.2), 1.21,
1.20 (d, 6H, CH3 iPr, JHH ¼ 6.9) ppm. P{1H} NMR (CD2Cl2, 25 ꢁC):
31
d
¼ 144.6 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 165e122 (m,
Ph), 115.6 (s, br, C1 p-cym), 103.25 (s, br, C4 p-cym), 90.62 (d, C2 p-
cym, JCP ¼ 4.2), 82.29 (d, C5 p-cym, JCP ¼ 3.6), 88.20 (br, C3 p-cym),
87.71 (br, C6 p-cym), 64.77, 64.19 (d, CH2, JCP ¼ 9.0, JCP ¼ 8.1), 31.26
(s, CH iPr), 22.39, 21.94 (s, CH3 iPr), 18.24 (s, CH3 p-cym), 16.47, 16.24
(CD2Cl2, 25 ꢁC):
d
d
¼ 87.3 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC):
¼ 165.4e122.1 (m, Ph), 105.22 (d, br, C1 p-cym), 97.60 (d, br, C4 p-
cym), 80.59 (d, C6 p-cym, JCP ¼ 4.3), 84.99 (d, C5 p-cym, JCP ¼ 6.2),
79.80 (d, C2 p-cym, JCP ¼ 2.5), 78.33 (d, br, C3 p-cym), 65.82 (d, CH2,
(d, CH3 phos, JCP ¼ 6.5, JCP ¼ 7.6) ppm. L ¼ 53.6 Uꢀ1 molꢀ1 cm2.
M
i
C50H57BClN2O2PRu (896.31): C 67.00, H 6.41, N 3.13, Cl 3.96; found C
66.79, H 6.30, N 3.01, Cl 4.12%.
JCP ¼ 12.9), 43.43 (s, NeCH3), 31.01 (s, CH Pr), 22.79, 22.44 (s, CH3
iPr), 18.23 (s, CH3 p-cym), 16.11 (d, CH3 phos, JCP ¼ 7.2) ppm.
L
¼ 48.8 Uꢀ1 molꢀ1 cm2. C49H55BClN2O2OsP (955.44): C 61.60, H
M
2.2.2. [OsCl(
h
6-p-cymene)(RNHNH2)L]BPh4 (4e6) [R ¼ H (4), Me
5.80, N 2.93, Cl 3.71; found C 61.38, H 5.69, N 2.80, Cl 3.84%.
(5), Ph (6); L ¼ P(OEt)3 (a), PPh(OEt)2 (b), PPh2OEt (c)]
6a: IR (KBr pellet): nNH ¼ 3287, 3248 (m) cmꢀ1. 1H NMR (CD2Cl2,
In a 25-mL three-necked round-bottomed flask were placed
25 ꢁC):
d
¼ 7.63e6.62 (m, 25H, Ph), 6.15 (t, br, 1H, NH), 5.67 (d, 2H,
0.13 mmol of the appropriate OsCl2(
h
6-p-cymene)L complex, an
HA, HD p-cym, JAB ¼ JCD ¼ 5.6 Hz), 5.60 (d, 1H, HC p-cym), 5.45 (d,
excess of NaBPh4 (0.26 mmol, 89 mg), 3 mL of ethanol and 5 mL of
dichloromethane. The resulting solution was cooled to ꢀ196 ꢁC and
a slight excess of the appropriate hydrazine RNHNH2 (0.14 mmol)
was added. The reaction mixture was allowed to reach room
temperature and then stirred for 24. The solvent was removed
under reduced pressure to give an oil which was triturated with
ethanol (2 mL). By cooling to ꢀ25 ꢁC of the resulting solution,
yellow crystals separated out, which were collected and recrystal-
lised from ethanol. Yield: 89 mg (75%) for4b, 75 mg (65%) for 5a,
85 mg (71%) for 5b, 98 mg (79%) for 5c, 87 mg (70%) for 6a, 100 mg
(78%) for 6b.
1H, HB p-cym), 5.60, 3.97 (d, br, 2H, NH2, JHH ¼ 9.5), 4.21e4.01 (m,
i
6H, CH2), 2.72 (m, 1H, CH Pr), 2.18 (s, 3H, CH3 p-cym), 1.28 (t, 9H,
CH3 phos, JHH ¼ 7.0), 1.27, 1.26 (d, 6H, CH3 iPr, JHH ¼ 6.9) ppm. 31P
{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 89.2 (s) ppm. 13C{1H} NMR (CD2Cl2,
25 ꢁC):
d
¼ 165e115 (m, Ph), 108.01 (d, C1 p-cym, JCP ¼ 4.0), 99.94 (s,
br, C4 p-cym), 86.17 (d, C2 p-cym, JCP ¼ 3.2), 83.89 (d, C5 p-cym,
JCP ¼ 6.3), 81.80 (d, C6 p-cym, JCP ¼ 6.5), 78.4 (s, br, C3 p-cym), 65.01
(d, CH2, JCP ¼ 10.5), 30.84 (s, CH iPr), 22.66, 22.37 (s, CH3 iPr), 18.51
(s, CH3 p-cym), 16.25 (d, CH3 phos, JCP
¼
6.7) ppm.
L
¼ 50.7 Uꢀ1 molꢀ1 cm2. C46H57BClN2O3OsP (953.42): C 57.95, H
M
6.03, N 2.94, Cl 3.72; found C 57.71, H 5.93, N 2.82, Cl 3.88%.
4b: IR (KBr pellet): nNH ¼ 3323, 3255, 3244 (m) cmꢀ1. 1H NMR
6b: IR (KBr pellet): nNH ¼ 3273 (m), 3245 (m, br) cmꢀ1. 1H NMR
(CD2Cl2, 25 ꢁC):
d
¼ 7.68e6.88 (m, 25H, Ph), 5.52 (d, 1H, HC p-cym,
(CD2Cl2, 25 ꢁC):
d
¼ 7.65e6.52 (m, 30H, Ph), 6.01 (t, br, 1H, NH,
JCD ¼ 5.7 Hz), 5.46 (d, 1H, HD p-cym), 5.44 (d, 1H, HB p-cym,
JAB ¼ 5.7), 5.35 (d, 1H, HA p-cym), 4.40, 4.27 (br, 2H, MeNH2),
4.09e3.75 (m, 4H, CH2), 2.65 (br, 2H, NeNH2), 2.53 (m, 1H, CH iPr),
2.02 (s, 3H, CH3 p-cym), 1.35, 1.34 (t, 6H, CH3 phos, JHH ¼ 7.0), 1.17,
JHH ¼ 8.8 Hz), 5.77, 5.44 (d, 2H, NH2, JHH ¼ JHH ¼ 8.8), 5.72 (d, 2H, HC,
HD, p-cym, JCD ¼ 5.8), 5.64 (d, 1H, HA p-cym, JAB ¼ 5.8), 5.58 (d, 1H,
HB p-cym), 4.17e3.79 (m, 4H, CH2), 2.62 (m, 1H, CH iPr), 2.05 (s, 3H,
CH3 p-cym), 1.32, 1.31 (t, 6H, CH3 phos), 1.23, 1.21 (d, 6H, CH3
1.15 (d, 6H, CH3 iPr, JHH ¼ 7.0) ppm. P{1H} NMR (CD2Cl2, 25 ꢁC):
iPr) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
NMR (CD2Cl2, 25 ꢁC):
d
¼ 98.9 (s) ppm. 13C{1H}
31
d
¼ 97.6 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 165e122 (m,
d
¼ 165e115 (m, Ph), 109.61 (s, br, C1 p-cym),
Ph), 108.4 (d, C1 p-cym, JCP ¼ 3.0), 96.93 (d, C4 p-cym, JCP ¼ 1.9),
83.78 (d, C2 p-cym, JCP ¼ 4.6), 83.20 (d, C5 p-cym, JCP ¼ 6.7), 80.67
(d, C6 p-cym, JCP ¼ 2.6), 77.53 (s, br, C3 p-cym), 65.03, 64.14 (d,
97.57 (s, br, C4 p-cym), 83.59 (s, br, C3 p-cym), 82.73 (s, br, C5 p-
cym), 80.17 (s, br, C6 p-cym), 76.90 (br, C2 p-cym), 65.32, 63.55 (d,
CH2, JCP ¼ 9.3, JCP ¼ 7.8), 31.05 (s, CH Pr), 22.50, 22.32 (s, CH3 iPr),
i
CH2, JCP ¼ 9.3, JCP ¼ 7.0), 30.81 (s, CH Pr), 22.46, 22.21 (s, CH3 iPr),
18.13 (s, CH3 p-cym), 16.32, 16.11 (d, CH3 phos, JCP
¼
7.4,
i
18.13 (s, CH3 p-cym), 16.31, 16.15 (d, CH3 phos, JCP
¼
6.5,
JCP ¼ 8.0) ppm. L ¼ 51.4 Uꢀ1 molꢀ1 cm2. C50H57BClN2O2OsP
M
JCP ¼ 7.6) ppm. L ¼ 51.1 Uꢀ1 molꢀ1 cm2. C44H53BClN2O2OsP
(985.47): C 60.94, H 5.83, N 2.84, Cl 3.60; found C 60.76, H 5.91, N
2.95, Cl 3.43%.
M
(909.37): C 58.11, H 5.87, N 3.08, Cl 3.90; found C 58.27, H 5.74, N
3.19, Cl 3.76%.
5a: IR (KBr pellet): nNH ¼ 3310, 3277 (w) cmꢀ1. 1H NMR (CD2Cl2,
2.2.3. [Ru(k2eO2CCH3)(
h
6-p-cymene){PPh(OEt)2}]BPh4 (7b)
6-p-cyme-
25 ꢁC):
d
¼ 7.33e6.87 (m, 20H, BPh4), 5.69 (d, 1H, HC p-cym,
A
solid sample of hydrazine complex [RuCl(h
JCD ¼ 5.9 Hz), 5.62 (d, 1H, HA p-cym, JAB ¼ 5.9), 5.57 (d, 1H, HD p-
cym), 5.45 (d, 1H, HB p-cym), 5.41, 5.24 (d, br, 2H, NH2), 4.13 (m, 6H,
CH2), 3.53 (m, br, 1H, NH), 2.68 (m, 1H, CH iPr), 2.51 (d, 3H, NeCH3,
JHH ¼ 6.4), 2.16 (s, 3H, CH3 p-cym), 1.34 (t, 9H, CH3 phos, JHH ¼ 7.0),
1.24, 1.22 (d, 6H, CH3 iPr, JHH ¼ 6.8) ppm. 31P{1H} NMR (CD2Cl2,
ne)(RNHNH2)L]BPh4 (1e3) (0.17 mmol) was placed in a 25-mL
three-necked round-bottomed flask fitted with a solid-addition
side arm containing a slight excess of Pb(OAc)4 (0.18 mmol,
80 mg). Dichloromethane (10 mL) was added, the solution cooled
to ꢀ30 ꢁC and Pb(OAc)4 portionwise added over 20e30 min to the
cold stirring solution. The solution was brought to 0 ꢁC, stirred for
5 min, and then the solvent was removed at 0 ꢁC under reduced
pressure. The oil obtained was triturated with ethanol (2 mL)
containing NaBPh4 (58 mg, 0.17 mmol) and the resulting solution
stirred at 0 ꢁC until a brown solid separated out, which was filtered
and crystallised from CH2Cl2 and ethanol. Yield: 62 mg (45%). 1H
25 ꢁC):
d
¼
69.8 (s) ppm.
L
¼
53.5 Uꢀ1 molꢀ1 cm2.
M
C41H55BClN2O3OsP (891.35): C 55.25, H 6.22, N 3.14, Cl 3.98; found C
55.07, H 6.35, N 3.02, Cl 4.21%.
5b: IR (KBr pellet): nNH ¼ 3289, 3255 (m) cmꢀ1. 1H NMR (CD2Cl2,
25 ꢁC):
d
¼ 7.61e6.86 (m, 25H, Ph), 5.60 (d, 2H, HA, HC p-cym,
JAB ¼ 5.9, JCD ¼ 6.0 Hz), 5.48 (d, 1H, HD p-cym), 5.52 (d, 1H, HB p-
cym), 4.85 (t, br), 4.60 (d, br) (2H, NH2, JHH ¼ 8.8, JHH ¼ 8.3),
4.16e3.84 (m, 4H, CH2), 3.47 (m, 1H, NH), 2.58 (m, 1H, CH iPr), 2.28
(d, 3H, NeCH3, JHH ¼ 6.2), 2.08 (s, 3H, CH3 p-cym), 1.38 (t, 6H, CH3
phos, JHH ¼ 7.0), 1.20, 1.19 (d, 6H, CH3 iPr) ppm. 31P{1H} NMR
NMR (CD2Cl2, 25 ꢁC):
d
¼ 7.56e6.86 (m, 25H, Ph), 5.59 (d, 2H, HC,
HD p-cym), 5.42 (d, 2H, HA, HB p-cym, JAB ¼ 6.0 Hz), 3.92 (m, 4H,
i
CH2), 3.13 (d, 3H, CH3COO, JHH ¼ 2.2), 2.36 (m, 1H, CH Pr), 1.84 (s,
3H, CH3 p-cym), 1.34 (t, 6H, CH3 phos, JHH ¼ 7.8), 1.19 (d, 6H, CH3
iPr) ppm. P{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 144.2 (s) ppm. 13C{1H}
31
(CD2Cl2, 25 ꢁC):
d
¼ 99.0 (s) ppm. L ¼ 52.9 Uꢀ1 molꢀ1 cm2.
M

G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
9
NMR (CD2Cl2, 25 ꢁC):
d
¼ 185.5 (d, br, COO), 165e121 (m, Ph), 113.6
+
(s, br, C1 p-cym), 99.0 (s, br, C4 p-cym), 89.2 (d, C2, C6 p-cym,
JCP ¼ 4.1), 86.7 (d, br, C3, C5 p-cym), 64.8 (d, CH2, JCP ¼ 9.0), 30.9 (s,
CH iPr), 25.1 (s, br, CH3COO), 22.7, 22.1 (s, CH3 iPr), 18.45 (s, CH3 p-
RNHNH2
-
M
BPh4
M
cym), 16.43 (d, CH3 phos, JCP ¼ 7.5) ppm. L ¼ 56.3 Uꢀ1 molꢀ1 cm2.
L
L
NaBPh4, EtOH
M
Cl
Cl
C46H52BO4PRu (811.76): C 68.06, H 6.46; found C 67.82, H 6.33%.
NH2NHR
Cl
1 - 6
2.2.4. [Os(CH3N2)(
This complex was prepared by treating the methylhydrazine
h
6-p-cymene){PPh(OEt)2}]BPh4 (8b)
Scheme 1. M ¼ Ru (1e3), Os (4e6); R ¼ H (1, 4), Me (2, 5), Ph (3, 6); L ¼ P(OEt)3 (a),
PPh(OEt)2 (b), PPh2OEt (c).
complex [Os(h
6-p-cymene)(CH3NHNH2){PPh(OEt)2}]BPh4 (5b)
(0.15 mmol, 139 mg) with Pb(OAc)4 at ꢀ30 ꢁC in CH2Cl2 following
the method used for the synthesis of 7b. Yield: 84 mg (63%). IR (KBr
3. Results and discussion
pellet): nNN ¼ 1698 (s) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC):
¼ 7.58e6.87
d
Half-sandwich dichloro complexes [15] of ruthenium and
(m, 25H, Ph), 5.60 (d, 2H, HA, HB p-cym, JAB ¼ 6.3 Hz), 5.50 (d, 1H p-
cym), 5.38 (d, 2H, HC, HD p-cym, JCD ¼ 6.3), 4.08e3.74 (m, 4H, CH2),
3.49 (d, 3H, CH3N, JHH ¼ 2.5), 2.70 (m, 1H, CH iPr), 2.41 (s, 3H, CH3 p-
cym), 1.35, 1.33 (t, 6H, CH3 phos, JHH ¼ 7.0), 1.24 (d, 6H, CH3 iPr,
osmium MCl2(
monosubstituted hydrazines RNHNH2 in the presence of NaBPh4 to
give hydrazine derivatives [MCl(
6-p-cymene)(RNHNH2)L]BPh4
h
6-p-cymene)L react with hydrazine NH2NH2 or
h
(1e6), which were isolated in good yields and characterised
(Scheme 1).
JHH ¼ 7.0) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 110.7 (s) ppm. 13
C
{1H} NMR (CD2Cl2, 25 ꢁC):
d
¼ 164e122 (m, Ph),113.00 (d, C1 p-cym,
Crucial for the separation of compounds 1e6 as solids was the
use of equimolar amounts of reagents and starting the reaction at
a low temperature. The addition of an excess of hydrazine to the
JCP ¼ 3.6), 98.75 (s, br, C4 p-cym), 86.40 (d, C5 p-cym, JCP ¼ 2.5),
86.00 (d, C3 p-cym, JCP ¼ 1.8), 81.83 (d, C2 p-cym, JCP ¼ 4.3), 81.67 (d,
C6 p-cym, JCP ¼ 3.5), 64.61, 64.50 (d, CH2, JCP ¼ 7.0), 37.05 (d, CH3N2,
JCP ¼ 5.7), 32.65 (s, CH iPr), 24.45, 24.40 (s, CH3 iPr), 20.02 (s, CH3 p-
dichloro precursors MCl2(h
6-p-cymene)L caused some decompo-
sition, which led to oily products difficult to purify.
cym), 16.35, 16.26 (d, CH3 phos, JCP
¼
7.3) ppm.
It is worth noting that only one chloride ligand in the MCl2(h
6-p-
L
¼ 52.9 Uꢀ1 molꢀ1 cm2. C45H52BN2O2OsP (884.92): C 61.08, H
M
cymene)L precursors may be substituted by RNHNH2 yielding
5.92, N 3.17; found C 59.94, H 5.81, N 3.28%.
monohydrazine derivatives 1e6. The use of an excess of hydrazine
never
ene)(RNHNH2)2L]2þ, but only led to decomposition products.
The hydrazine complexes of Ru and Os [MCl(
6-p-cyme-
yielded
bis(hydrazine)
complexes
[M(h
6-p-cym-
2.2.5. OsCl(CH3N]NH)(
This complex was prepared only in solution by reacting
[Os(CH3N2)( (8b) (100 mg,
6-p-cymene){PPh(OEt)2}]BPh4
h
6-p-cymene){PPh(OEt)2}]þBPh4ꢀ (9b)
h
h
ne)(RNHNH2)L]BPh4 (1e6) were obtained as yellow or orange
solids, stable in air and in solution of polar organic solvents, where
they behave as 1:1 electrolytes [23]. Analytical and spectroscopic
(IR and 1H, 31P, 13C NMR) data support the proposed formulation,
which was further confirmed by X-ray crystal structure determi-
0.11 mmol) in 4 mL of CD2Cl2 with a slight excess of HCl (0.12 mmol,
40
m
L of a 3 M solution in diethylether) at ꢀ80 ꢁC. The solution was
allowed to reach 0 ꢁC and then NMR spectra were recorded.1H NMR
(CD2Cl2, 25 ꢁC):
d
¼ 13.6 (s, br, 1H, ¼NH), 7.70e6.98 (m, 25H, Ph),
5.58, 5.53, 5.40, 5.31 (d, 4H, Ph p-cym), 4.13, 3.98 (m, 4H, CH2), 3.20
(t, 3H, CH3N¼), 2.66 (m, 1H, CH iPr), 2.03 (s, 3H, CH3 p-cym), 1.33 (t,
6H, CH3 phos), 1.21, 1.18 (d, 6H, CH3 iPr) ppm. 31P{1H} NMR (CD2Cl2,
nation of complex [OsCl(h
6-p-cymene)(PhNHNH2){PPh(OEt)2}]
BPh4 (6b), the ORTEP [24] of which is shown in Fig. 1.
The structure consists of a tetraphenylborate anion (not shown)
25 ꢁC):
d
¼ 101.02 (s) ppm.
and a cation formed of an osmium atom
p-cymene molecule and to three donor atoms e chloride, phos-
phonite PPh(OEt)2 and phenylhydrazine- -N ligands e leading to
h
6-coordinated to a
k
2.3. X-ray crystallography
the formation of a “three-legged piano stool” structure. Selected
bond lengths and angles for the metal environment of the cation
are listed in Table 1. The overall geometry of the complex should be
considered as octahedral, although the angles PeOseCl, N(1)e
Crystallographic data were collected on a Bruker Smart 1000
CCD diffractometer at CACTI (Universidade de Vigo) with graphite
monochromated MoeK
a
radiation (
l
¼ 0.71073 Å), and were cor-
rected for Lorentz and polarisation effects. The software SMART
[17] was used for collecting frames of data, indexing reflections, and
the determination of lattice parameters, SAINT [18] for integration
of intensity of reflections and scaling, and SADABS [19] for empirical
absorption correction.
P
The structures were solved and refined with the Oscail program
[20] by Patterson (6b) or direct (7b) methods and refined by a full-
matrix least-squares based on F2 [21]. For the compound 6b, the
Squeeze program was used to correct the reflection data for the
diffuse scattering due to disordered EtOH solvent [22]. Compound
7b crystallises in the monoclinic P21/n space group with two unit
formula in the asymmetric unit, and any attempt to look for any
other symmetry was unsuccessful. Careful study of the structures
showed us true differences between both units (see discussion).
Non-hydrogen atoms were refined with anisotropic displacement
parameters. Hydrogen atoms were included in idealised positions
and refined with isotropic displacement parameters, except that on
the NH group (in 6b), which was found in the electronic density
map and refined with isotropic displacement parameters. Details of
crystal data and structural refinement are given in Table 3.
Os
N1
Cl
N2
Fig. 1. ORTEP [24] view of the cation of 6b, drawn at 30% probability level. Tetra-
phenylborate anion and most hydrogen atoms have been omitted for clarity. Atom
labelled as P represents a PPh(OEt)2 group.

10
G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
absorptions at 3317e3261 cmꢀ1, attributed to the nNH of the
Table 1
Selected bond lengths [Å] and angles [ꢁ] for 6b.
methylhydrazine. The 1H NMR spectra confirm the presence of
CH3NHNH2, showing two slightly broad multiplets between 5.18
and 3.70 ppm for the NH2 protons, only one multiplet at
Os-CT1
1.7217(2)
2.154(4)
2.287(4)
2.193(5)
2.197(5)
1.437(5)
OseP
OseCl
OseC(24)
OseC(25)
OseC(26)
N(2)eC(1)
2.2948(13)
2.4060(12)
2.235(5)
2.168(5)
2.264(4)
1.415(6)
OseN(1)
OseC(21)
OseC(22)
OseC(23)
N(1)eN(2)
4.29e3.31 ppm of the NH proton, and
a sharp doublet at
2.52e2.14 ppm of the methyl substituent of the CH3NHNH2 ligand.
The proton signals of the phenylhydrazine ligand in complexes
[MCl(h a higher
6-p-cymene)(PhNHNH2)L]BPh4 (3, 6) fall at
CT1eOseN(1)
CT1eOseP
CT1eOseCl
126.78(11)
129.45(3)
129.31(3)
114.7(3)
N(1)eOseP
N(1)eOseCl
PeOseCl
88.39(11)
81.46(11)
85.78(5)
115.9(4)
frequency than the related hydrazines. In particular, a broad triplet
appears at 6.15e5.38 ppm, and was attributed to the NH protons,
whereas two slightly broad multiplets, due to the diastereotopic
NH2 protons, appear between 5.77 and 4.38 ppm, fitting the pres-
ence of the phenylhydrazine ligand.
N(2)eN(1)eOs
C(1)eN(2)eN(1)
CT represents the centroid of the benzene ring of the p-cymene ligand.
The 1H NMR spectra of all hydrazine complexes 1e6 also show
the characteristic signals of both p-cymene and phosphite ligands,
with splitting of some signals due to the presence of a chiral centre
in the molecule. The 13C spectra support the presence of the
p-cymene and phosphite ligands and, in the case of methylhy-
drazine complexes, also show a singlet at 43.46e43.43 ppm for the
methyl substituent. In the temperature range between þ20
and ꢀ80 ꢁC, the 31P NMR spectra are sharp singlets, matching the
proposed formulation for the complexes.
OseP and N(1)eOseCl are more acute than expected, with an
average of 85.2(2)ꢁ. The lower value, 81.4(2)ꢁ, corresponds to the
NeOseCl angle, and it is noteworthy that a similar effect was found
in a recently published benzylideneamine ruthenium complex [25].
Any weak hydrogen bond interaction (not found) or simply steric
hindrance of the phosphane ligand could explain this value.
The average OseC bond distance for the p-cymene ligand is
2.224(5) Å, and the distance from the osmium atom to the centroid
of the benzene ring of the cymene ligand is 1.7217(2) Å. These
values are slightly shorter than those found in other related
complexes [26] and show more regularity than other p-cymene
osmium derivatives. As usual for this kind of complex, the longer
value corresponds to the atom labelled as C(21), the isopropyl
substituted carbon atom. The OseP bond length, 2.295(2) Å, is
similar to other related complexes [26] and does not need further
comment. The OseN bond distance, 2.154(4) Å, is shorter than
those found in other hydrazine osmium complexes [5b,11c,27]. To
the best of our knowledge [CSD database, CSD version 5.32
(February 2011 updated)], except for a cluster compound contain-
ing a bridging pentafluorophenylhydrazine ligand [28], no other
phenylhydrazine osmium complex has been described. The
hydrazine ligand adopts a trans conformation in the OseNeNeC
group, but the OseNeNeC torsion angle, 160.6(4)ꢁ, is slightly
different from the quasi-planar value found in other phenyl-
hydrazine complexes [29]. The N(1)eN(2) bond distance, 1.437(5)
Å, is consistent with a NeN single bond, and the N(2)eC(ring) bond
distance is slightly shorter, 1.415(6) Å, but still consistent with a sp3
character for the nitrogen atom. The angles around both nitrogen
atoms are very similar, 114.7(3) and 115.9(4)ꢁ. These values usually
differ more greatly from each other, as found both in a phenyl-
hydrazine molybdenum complex [29], with values of 112.8(4) and
Hydrazine complexes of ruthenium have been reported with
several supporting ligands such as phosphine, phosphite, iso-
cyanide, diene, arene and tris(pyrazolyl)borate [1e4,11a,31].
Instead, hydrazine complexes of osmium are rare [8a,11c,27,32] and
no example with arene ligands has been reported. The use of
OsCl2(h
6-p-cymene)L as a precursor allowed the first arene osmium
hydrazine complexes to be prepared.
Reactivity studies of our hydrazine complexes 1e6 towards
oxidation with Pb(OAc)4 were undertaken, and the results are
shown in Scheme 2 for Ru compounds and Scheme 3 for Os ones.
Hydrazine complexes of ruthenium [RuCl(h
6-p-cyme-
ne)(RNHNH2)L]BPh4 (1e3) react with an equimolar amount of
Pb(OAc)4 at ꢀ30 ꢁC in CH2Cl2 to give a purple solution, from which
a
reddish solid, characterised as the acetate complex
[Ru(k2eO2CCH3)( 6-p-cymene)L]BPh4 (7), was obtained. The
h
formation of the chelate complex 7 is somewhat surprising,
because the coordinated hydrazines are known to undergo oxida-
tion with Pb(OAc)4 to give diazene RN]NH derivatives. However,
taking into account the fact that hydrazine complexes 1e3 do not
react with the acetate ion, the formation of complex 7 may be
explained on the basis of the path shown in Scheme 4.
Pb(OAc)4 oxidises the coordinate hydrazine to diazene [A],
which is probably unstable and can be substituted by the acetate
117.4(5)ꢁ,
or
in
the
cationic
osmium
complex
ion. The
substitution of the Clꢀ ligand, affording the final
[Ru(k2eO2CCH3)( 6-p-cymene)L]BPh4 (7) derivative.
k
2-coordination of the CH3COOꢀ group gives also rise to
[Os(NH2NH2)2{P(OEt)3}4]2þ [11c], where the angles around the
donor nitrogen atoms are 120ꢁ (sp2 hybridization). Values close to
120ꢁ are also found for dinuclear molybdenum complexes with
both phenyldiazenido and phenylhydrazine [30].
h
Different behaviour is shown by osmium complexes 4e6, which
react with Pb(OAc)4 at ꢀ30 ꢁC to give, in the case of the methyl-
The IR spectra of hydrazine complexes [MCl(
h
6-p-cyme-
hydrazine complex [OsCl(h
6-p-cymene)(CH3NHNH2)L]BPh4, an
ne)(NH2NH2)L]BPh4 (1, 4) show three medium-intensity bands at
3336e3239 cmꢀ1, attributed to the nNH of the hydrazine ligand.
However, its presence is confirmed by the 1H NMR spectra, which
show two slightly broad multiplets between 4.40 and 3.51 ppm,
attributed to the metal-N-bonded NH2 group. The multiplicity of
signals is due to the presence of a chiral centre in the molecule,
which makes the two NH2 protons diastereotopic, with different
chemical shifts and JHH values of about 9 Hz. A slightly broad
multiplet at 2.73e2.63 ppm is also present in the 1H NMR spectra
which, in a COSYexperiment, was correlated with two multiplets at
4.40e3.51 ppm and attributed to the end-on NH2 group of
hydrazine.
orange solid characterised as the methyldiazenido derivative
[Os(CH3N2)(h
6-p-cymene)L]BPh4 (8) (Scheme 3). Instead, reaction
+
+
Pb(OAc)4
-
Ru
Cl
Ru
BPh4
L
L
CH2Cl2, -30 °C
O
NH2NHR
O
C
7
CH3
Scheme 2. R ¼ H, Me, Ph; L ¼ PPh(OEt)2 (b).
The IR spectra of methylhydrazine complexes [MCl(
ene)(CH3NHNH2)L]BPh4 (2, 5) show two medium-intensity
h
6-p-cym-

G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
11
+
+
+
+
+
-H+
Pb(OAc)4
Pb(OAc)4
Os
H
Os
-
Os
Os
BPh4
L
L
CH2Cl2, -30 °C
L
Cl
CH2Cl2, -30 °C
Cl
N
N
NH2NHCH3
Cl
L
NH2NHCH3
N
CH3
[ B ]
N
8
+
CH3
-Cl-
Os
Os
L
Cl
L
Pb(OAc)4
N
N
N
Os
decomposition products
L
CH2Cl2, -30 °C
CH3
N
Cl
NH2NHR
[ C ]
8
CH3
Scheme 3. R ¼ H, Ph; L ¼ PPh(OEt)2 (b).
Scheme 5. L ¼ PPh(OEt)2 (b).
of the hydrazine and phenylhydrazine complexes with Pb(OAc)4 led
to an orange solution, from which only intractable oils containing
decomposition products were isolated. The formation of methyl-
diazenido complex 8 from reaction of the methylhydrazine complex
with Pb(OAc)4 is not surprising, and may be explained on the
basis of oxidation of the coordinate CH3NHNH2 to methyldiazene
CH3N]NH, giving the intermediate complex [B] (Scheme 5).
The diazene hydrogen atom is known to be acidic [1,5e,33], and
can be deprotonated by the acetate ion present in solution, giving
the double-bent methyldiazenido complex [C]. A rearrangement of
this double-bent ArNꢀ2 ligand to singly-bent ArNþ2 should involve
a 2eꢀ reduction of the central metal to Os(0), followed by concur-
rent dissociation of the chloride ligand [5e,33] to give the final
cationic methyldiazenido derivative 8.
octahedral, with PeRueO angles 85.2(1) and 88.6(1)ꢁ. The third
angle between the legs corresponds to the chelating angle, with an
average value of 61.4(2)ꢁ, similar to that found in other octahedral
carbonate complexes, such as [Ru(k2eO2CCH3)2{1,10-bis(diphenyl-
phosphino)ferrocene}], average 61.0(2)ꢁ [34], the cationic [Ru(N3
-
P)(k2eO2CCH3)]þ, 60.61(6)ꢁ [35], or the [Ru(k2eO2CCH3)Cl(p-
cymene)], 60.31(7)ꢁ [36].
The coordination of the acetate ligand, with differences between
RueO bonds of only 0.006 Å (i.e. within the margin of error), is
much more symmetrical than that found in other acetate
complexes [11a,36b,37]. The RueO bond lengths are, on average,
2.122(4) Å and are within the limits found in the above-mentioned
carboxylate complexes. The RueP bond length, on average 2.293(2)
Å, is in fact the same value found in other pseudo-octahedral
Complexes 7 and 8 were isolated as reddish (7) or orange (8)
solids, stable in air and in solution of polar organic solvents, where
they behave as 1:1 electrolytes [23]. Analytical and spectroscopic
(IR and 1H, 31P, 13C NMR) data support the proposed formulations,
which were further confirmed by X-ray crystal structure determi-
[Ru(h
6-p-cymene)LL’{PPh(OEt)2}]þ cationic compounds [25] and
is similar to other related compounds [38]. The average RueC bond
distance is 2.209(6) Å for the ruthenium atom labelled as Ru(1) and
slightly longer, 2.218(7) Å, for the ruthenium atom labelled as Ru(2)
(Table 2). This may be an effect of the different arrangement of the
ligands around the metal (see below). In any case, these values are
in average slightly shorter than those found in other p-cymene
ruthenium complexes [15,38,39]. The Ruecentroid arene ring
distances are 1.7085(5) and 1.7152(5) Å, respectively, also perhaps
as a consequence of the different arrangement of the ligands
around the metal. These differences are clear in Fig. 3. The
p-cymene ligand, in the molecule containing Ru(1), is much more
planar than in the molecule containing Ru(2), with rms deviation of
0.009 or 0.032, respectively. In the molecule containing Ru(1), the
longest RueC bond length is that quasi-trans to the phosphane
ligand labelled as C(22), 2.243(5) Å and the two substituted (iPr or
Me) carbon atoms are both at 2.219(6) Å from the metal. Other
RueCring bond lengths are shorter. But in the molecule containing
Ru(2), the longest RueC bond length is the methyl-substituted
carbon, since two influences are found at this atom, the trans
nation of complex [Ru(k2eO2CCH3)( 6-p-cymene){PPh(OEt)2}]
h
BPh4 (7b), the ORTEP [24] of which is shown in Fig. 2.
Compound 7b crystallises in the monoclinic P21/n space group
with two tetraphenylborate anions and two cationic metal
complexes. In order to show the metal environment, Fig. 2 repre-
sents only one of the cationic complexes; Fig. 3 shows the two
cationic complexes and their arrangement. Both cations are formed
of a ruthenium atom in a classical “three-legged piano stool”
structure by means of a h
6-coordinating p-cymene molecule, and
three donor atoms as legs, a phosphorus atom for a phosphonite
PPh(OEt)2 ligand, and two oxygen atoms from a carboxylate anion.
Selected bond lengths and angles are listed in Table 2. The
geometrical anion parameters are comparable within the margin of
error, but the arrangement of the ligands around the ruthenium
atom is quite different in both molecules, as will be explained
below. Coordination of both ruthenium atoms is best considered as
L
L
L
Cl
Cl
O
+Ac-
Pb(OAc)4
-30 °C
Ru
Ru
R
C
CH3
Ru
O
NH2NHR
N
N
H
1 - 3
[ A ]
7
Scheme 4. L ¼ PPh(OEt)2 (b).

12
G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
Table 2
Selected bond lengths [Å] and angles [ꢁ] for 7b.
C29
C27
Ru(1)eCT1
1.7085(5)
2.219(6)
2.243(5)
2.193(5)
2.219(6)
2.192(6)
2.190(6)
2.121(4)
2.127(4)
2.2966(15)
1.267(9)
1.275(9)
1.501(9)
Ru(2)eCT2
1.7152(5)
2.248(6)
2.173(6)
2.179(6)
2.285(7)
2.243(6)
2.182(6)
2.117(4)
2.121(4)
2.2884(16)
1.245(7)
1.281(7)
1.484(8)
Ru(1)eC(21)
Ru(1)eC(22)
Ru(1)eC(23)
Ru(1)eC(24)
Ru(1)eC(25)
Ru(1)eC(26)
Ru(1)eO(12)
Ru(1)eO(11)
Ru(1)eP(1)
Ru(2)eC(51)
Ru(2)eC(52)
Ru(2)eC(53)
Ru(2)eC(54)
Ru(2)eC(55)
Ru(2)eC(56)
Ru(2)eO(41)
Ru(2)eO(42)
Ru(2)eP(2)
C26
C21
C25
C24
C28
C210
C22
C23
P1
Ru1
C(11)eO(12)
C(11)eO(11)
C(12)eC(11)
C(41)eO(41)
C(41)eO(42)
C(41)eC(42)
O11
C11
C12
O12
CT1eRu(1)eO(12)
CT1eRu(1)eO(11)
O(12)eRu(1)eO(11)
CT1eRu(1)eP(1)
O(12)eRu(1)eP(1)
O(11)eRu(1)eP(1)
132.99(13)
135.94(13)
61.7(2)
128.22(5)
88.26(13)
86.74(12)
CT2eRu(2)eO(41)
CT2eRu(2)eO(42)
O(41)eRu(2)eO(42)
CT2eRu(2)eP(2)
O(41)eRu(2)eP(2)
O(42)eRu(2)eP(2)
132.36(11)
133.20(11)
60.99(16)
131.05(5)
88.91(11)
85.74(12)
CT represents the centroid of the benzene ring of the p-cymene ligand.
Fig. 2. ORTEP [24] view of one of the cations found in the asymmetric unit of 7b,
drawn at 20% probability level. Tetraphenylborate anion and hydrogen atoms have
been omitted for clarity.
The IR spectrum of methyldiazenido complex [Os(CH3N2)(h
6-p-
cymene){PPh(OEt)2}]BPh4 (8b) shows a strong band at 1698 cmꢀ1
,
influence of the phosphane ligand and the fact of being substituted
by a methyl group. The arrangement of the substituents at the
phosphane ligand is also quite different, as Fig. 3 shows. In the
molecule containing Ru(1), the phenyl ring is as far as possible from
the acetate ligand and apparently parallel to the p-cymene ring,
although the dihedral angle between best planes is 24.3(2)ꢁ. In the
molecule containing Ru(2), the phenyl ring is as far as possible from
the p-cymene ligand and almost perpendicular to it, with a dihedral
angle between best planes of 89.6(2)ꢁ. The position of the phenyl
ring and one ethoxy group are interchangeable, and this allows the
different arrangement of the p-cymene ligand in the solid state.
Besides the signals characteristic of the p-cymene, phosphine
attributed to the nNN of the methyldiazenido ligand. A comparison
of this nNN value with those of known alkyl- and aryldiazenido
complexes (1730e1660 cmꢀ1) [5e,f,33,40e42], whose structures
were determined by X-ray analysis, also suggests the presence of
Table 3
Crystal data and structure refinement.
Identification code
6b
7b
Empirical formula
Formula weight
Temperature
C50H57BClN2O2OsP
985.41
293(2) K
C92H104B2O8P2Ru2
1623.45
293(2) K
and BPh4 anion, the 1H NMR spectrum of [Ru(k2eO2CCH3)(
h
6-p-
Wavelength
0.71073 Å
0.71073 Å
Crystal system
Space group
Unit cell dimensions
Triclinic
Pꢀ1
Monoclinic
P21/n
cymene){PPh(OEt)2}]BPh4 (7b) shows a doublet at 3.13 ppm, which
was attributed to the methyl group of the k2eCH3COOꢀ ligand. In
a HMQC experiment, this signal was correlated with a singlet at
25.1 ppm in the 13C NMR spectrum, matching the proposed
assignment. The 13C spectrum also shows a doublet at 185.5 ppm,
due to the carbonyl carbon resonance of the acetate ligand, whereas
the 31P spectrum appears as a sharp singlet, as expected for
a geometry in solution like that observed in the solid state.
a ¼ 11.6146(15) Å
b ¼ 12.3314(16) Å
c ¼ 17.946(2) Å
a ¼ 9.6018(9) Å
b ¼ 20.2416(18) Å
c ¼ 43.328(4) Å
a
b
g
¼ 93.211(2)ꢁ
¼ 91.902(2)ꢁ
¼ 108.219(2)ꢁ
a
b
g
¼ 90ꢁ
¼ 92.398(2)ꢁ
¼ 90ꢁ
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
2434.1(5) Å3
2
8413.6(13) Å3
4
1.344 Mg/m3
2.745 mmꢀ1
1000
1.282 Mg/m3
0.451 mmꢀ1
3392
Crystal size
Theta range for
data collection
Index ranges
0.28 ꢂ 0.20 ꢂ 0.19 mm 0.46 ꢂ 0.25 ꢂ 0.19 mm
1.74e25.03 ꢁ 1.38e25.01 ꢁ
C21
ꢀ13 ꢃ h ꢃ 13; ꢀ14 ꢃ k ꢀ11 ꢃ h ꢃ 11; ꢀ20
ꢃ 14; ꢀ21 ꢃ l ꢃ 21
ꢃ k ꢃ 24; ꢀ47 ꢃ l ꢃ 51
C26
C22
Reflections collected
Independent reflections
Reflections observed (>2
Data Completeness
18242
44446
P2
C56
C55
8496 [R (int) ¼ 0.0395] 14795 [R (int) ¼ 0.0887]
C51
Ru2
s)
6625
7145
0.988
0.997
P1
C52
C53
Ru1
C24
Absorption correction
Semi-empirical from
equivalents
Semi-empirical from
equivalents
C25
C23
Max. and min. transmission 1.000 and 0.817
Refinement method
1.000 and 0.857
Full-matrix
Full-matrix
least-squares on F2
least-squares on F2
14795/0/967
0.984
Data/restraints/parameters 8496/0/532
C54
Goodness-of-fit on F2
0.975
Final R indices [I > 2
s
(I)]
R1 ¼ 0.0351
wR2 ¼ 0.0702
R1 ¼ 0.0533
wR2 ¼ 0.0763
R1 ¼ 0.0510
wR2 ¼ 0.1032
R1 ¼ 0.1447
wR2 ¼ 0.1419
0.646 and ꢀ0.474 e Åꢀ3
R indices (all data)
Fig. 3. The different arrangement of the ligands in the two cations found in the
asymmetric unit of 7b (drawn along the Ru-CT vector). Only labelling scheme of the p-
cymene ligands is shown. Ethyl groups on the phosphane are not show for clarity.
Largest diff. peak and hole 1.256
and ꢀ0.554 e Åꢀ3

G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
13
p-cymene)L]BPh4 and methyldiazenido complexes [Os(CH3N2)(
h
6-p-
+
+
cymene)L}]BPh4 to be prepared. Half-sandwich methyldiazene
cations [OsCl(CH3N]NH)(
h
6-p-cymene)L}]þ werealsoobtained from
+HCl
Os
8b
Os
the reaction of methyldiazenido complexes with HCl.
CH3
-HCl
exc. NEt3
L
L
Cl
N
N
N
Acknowledgement
H
N
The financial support of MIUR (Rome)-PRIN 2009 is gratefully
acknowledge. We thank Mrs. Daniela Baldan, from the Università
Ca’ Foscari Venezia, for her technical assistance.
9b
CH3
Scheme 6. L ¼ PPh(OEt)2.
Appendix A. Supplementary material
a singly-bent methyldiazenido ligand, formally present as CH3Nþ2 .
The metal centre thus appears to be in a formal oxidation state of
zero [Os(0)].
CCDC 830874 and 830875 contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge at www.ccdc.ac.uk/conts/retrieving.html.
Besides the characteristic signals of the supporting ligands
p-cymene and PPh(OEt)2 and of the BPh4 anion, the 1H NMR
spectrum of 8b shows a singlet at 3.49 ppm, attributed to the
methyl substituent of the methyldiazenido ligand. The 13C NMR
spectrum supports the presence of these ligands, showing
a doublet at 37.05 ppm which, in a HMQC experiment, was corre-
lated with the singlet at 3.49 ppm observed in the proton spectrum
and attributed to the methyl carbon resonance of the diazo CH3N2
ligand. The spectrum also shows the signals of the p-cymene and
phosphonite carbon resonances, whereas the 31P NMR spectrum
appears as a sharp singlet, fitting the proposed formulation for 16-
electron methyldiazenido derivative 8b.
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[Os(CH3N2)(
h
6-p-cymene){PPh(OEt)2}]BPh4
(8b)
reacts with Brønsted acid HCl to give the methyldiazene complex
[OsCl(CH3N]NH)(
h
6-p-cymene){PPh(OEt)2}]BPh4 (9b), as shown
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in Scheme 6.
The reaction proceeds with protonation of the diazenido at the
Na
nitrogen atom, to give the methyldiazene ligand CH3N]NH. The
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[OsCl(CH3N]NH)(h
6-p-cymene){PPh(OEt)2}]þBPhꢀ4 (9b). Unfortu-
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solid state. However, monitoring the progress of the reaction
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a slightly broad signal appears at 13.6 ppm, characteristic of the
diazene hydrogen resonance [11c,e,f]. As the signals of the dia-
zenido 8b species disappear, a triplet at 3.20 ppm does appear
which, in a COSY experiment, was correlated with the diazene
signal at 13.6 ppm and was attributed to the methyl group of the
CH3N]NH ligand. In the proton spectrum, new signals for the p-
cymene and phosphonite ligands also appear, whereas a new
singlet at 101.02 ppm was observed in the 31P spectrum, matching
the proposed formulation for 9b. It is worth noting that the addi-
tion of an excess of NEt3 to a solution containing methyldiazene
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h
6-p-cymene){PPh(OEt)2}]þBPh4ꢀ (9b)
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caused the solution to change colour, with the formation of
methyldiazenido
derivative
[Os(CH3N2)(h
6-p-cymene)
{PPh(OEt)2}]þBPh4ꢀ (8b). NEt3 deprotonates methyldiazene CH3N]
NH in 9b, with the concurrent loss of Clꢀ and formation of meth-
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containing a methyldiazene ligand, stabilised by the half-sandwich
fragment [OsCl(h
6-p-cymene)L].
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-

14
G. Albertin et al. / Journal of Organometallic Chemistry 697 (2012) 6e14
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