The dominant steric effect in the synthesis of ammine hydrido- and chlorido-Ru(II)-N,N-dimethylhydrazine and mixed alkyl-aryl phosphine complexes: Novel methyldiazene reduction intermediates

Article abstract of DOI:10.1016/j.ica.2015.08.019

Novel cationic hydrido complexes [RuH(1,5-cod)(NH₃)(NH₂NMe₂)₂](X) (X = PF₆, BPh₄) and chlorido-ammine complexes [RuCl(1,5-cod)(NH₃)₂(NH₂NMe₂)](X)

Full text of DOI:10.1016/j.ica.2015.08.019

Inorganica Chimica Acta 437 (2015) 133–142
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
The dominant steric effect in the synthesis of ammine hydrido- and
chlorido-Ru(II)-N,N-dimethylhydrazine and mixed alkyl–aryl phosphine
complexes: Novel methyldiazene reduction intermediates
⇑
Frederick P. Malan, Afsar Ali, Eric Singleton, Reinout Meijboom
Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park 2006, Johannesburg, South Africa
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 June 2015
Received in revised form 9 August 2015
Accepted 14 August 2015
Available online 2 September 2015
Novel cationic hydrido complexes [RuH(1,5-cod)(NH3)(NH2NMe2)2](X) (X = PF6, BPh4) and chlorido-
ammine complexes [RuCl(1,5-cod)(NH3)2(NH2NMe2)](X) (X = PF6, BPh4), were isolated from the reaction
of the polymeric [RuCl2(1,5-cod)]x with NH2NMe2. Reaction of the hydrido complexes with the phosphine
ligands PMe3, PMe2Ph, P(OMe)2Ph resulted in the formation of monohydrido-phosphine complexes,
whereas reaction with the bulkier PMePh2 ligand gave dihydrido-phosphine complexes. Similar reactions
of the chlorido-ammine complexes with the phosphine ligands PMe3, PMe2Ph, P(OMe)2Ph, and PMePh2
all sequentially substituted the NH2NMe2 and the 1,5-cod ligands to give the chlorido-ammine phosphine
complexes. All complexes were fully characterised and the single crystal X-ray structures were
Keywords:
Ruthenium
Cationic
Dimethylhydrazine
Nitrogenase
determined for [RuH{P(OMe)2Ph}5](BPh4), [RuH2(PMePh2)4], [{Ru(PMe2Ph)3}2(
(NH3)2(PMe2Ph)3](PF6), and [RuCl(NH3)(PMe2Ph)4](PF6). Intramolecular strain between coordinated
-donor ligands in the Ru(II)-NH2NMe2 precursor complexes as well as the relative steric bulk of incom-
ing -donor ligands were found to be chemically directing in the formation of monohydrido-, bishydrido-
, mono-ammine, and bis-ammine ruthenium(II) complexes.
l-F)3](PF6), fac-[RuCl
r
Intramolecular strain
r
Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
throughout 1977–1987, who reported the synthetic and
catalytically active complexes [CpRuX(cod)] (X = H, Cl, Br) [18c]
and the first metallacyclopentatriene complex [CpRu(C4Ph2H2)]
[18a,18b], all emanated from the use of the Ru(II) complexes of
[RuH(1,5-cod)(NH2NHR)3](X) (R = H, Me; X = PF6, BPh4) as
precursors [16,17d,19]. These catalytically important Ru–H com-
plexes were found to be reactive precursors to a range of allyl-
and cyclooctadiene ruthenium(II) species which has significance
in hydride transfer reactions [16,17,20–21].
In light of the well-documented N–N fission reactions of Ru(II)-
NH2NH2 complexes to form Ru(II)-NH3 complexes, along with their
important application in DNA binding studies [2c,22], reports on
the use of the Ru(II)-hydrazine complexes as precursors in these
studies remain limited [2a,10,15,23]. Furthermore, reports of in-
situ decomposition of NH2NMe2 to form NH3 as a by-product are
to the best of our knowledge non-existent.
These NH2NMe2- and NH3-ruthenium(II) complexes are sta-
bilised by neutral ancillary phosphine and phosphite ligands, to
form isolable intermediates for the conversion of dinitrogen to
ammonia [1b,23–24]. Extensive research by Sellman et al.
showed that the phosphine-containing [Ru(PiPr3)(‘N2Me2S2’)]
complex fragment is capable of binding N2H2, N2H4, NH3, and H2,
all nitrogenase-relevant molecules [6,7b,25]. The latter fragment
Synthetic routes to complexes of Ru(II) containing hydrazine
and other partially reduced dinitrogen ligands are still of great
importance, as their products are shown to be useful intermediates
in the numerous synthetic, organic functionalisation, catalytic, and
industrial processes, as well as in biologically important nitroge-
nase and nitrogen fixation processes [1–5]. Numerous recent
reports deal with Ru(II)-hydrazine complexes and their role as
nitrogenase-relevant molecules whereby the isolation of hydrazine
intermediates in the enzyme turnover is of great importance [5a,6–
11]. Ruthenium(II) counterparts of the unstable and reactive iron
intermediates are generally more stable, which allows the
isolation of intermediate species [1b,5b,10,12,13].
An extensive range of stable cationic and neutral ruthenium(II)
species containing the hydrazine ligands NH2NHR (R = H, Me) have
been reported, and primarily includes complexes with carbonyl
[1e,6b], phosphine and phosphite [1e,2a,6,14,10,15,16a], 1,5-
cyclooctadiene [2b,16], cyclopentadienyl [17d,18], and p-cymene
ancillary ligands [6a]. The pioneering work of Singleton et al.
⇑
Corresponding author.
E-mail address: rmeijboom@uj.ac.za (R. Meijboom).
http://dx.doi.org/10.1016/j.ica.2015.08.019
0020-1693/Ó 2015 Elsevier B.V. All rights reserved.

134
F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
3
containing only the bulky PPh3 and PCy3 phosphine ligands
allowed for the nitrogenase-relevant molecules L = N2, N2H4, NH3,
and CO to coordinate, forming the species [Ru(L)(PR3)(‘N2Me2S2’)]
[6b].
We report four novel Ru(II)-NH2NMe2 complexes, all of which
contain the in-situ generated ammine ligands produced from the
combined effect of nitrogenase-mimicking and NH4PF6 hydrolysis.
These complexes were isolated during the reinvestigation of the
known reaction of [RuCl2(1,5-cod)]x with NH2NMe2. The reactivity
and ligand-competing behaviour of these complexes are also
demonstrated in the reactions with selected phosphine and phos-
phonite ligands to produce a range of novel monohydrido-, bishy-
drido-, mono-ammine, and bis-ammine Ru(II) complexes.
(s, NH3, 3H); 1.56 (s, H2O); 1.67 (t, JHH = 11 Hz, CH2 of cod, 2H);
2.26 (m, CH2 of cod, 4H); 2.44 (s, NCH3 trans to cod, 6H); 2.73
(s, NCH3 cis to cod, 3H); 3.06 (s, CH2 of cod, 2H); 4.56
3
3
(d, JHH = 10 Hz, @CH of cod, 2H); 4.99 (d, JHH = 10 Hz, @CH of
cod, 2H); 6.08 (br s, NH2, 2H). 13C{1H} NMR (ppm) (101 MHz,
(CD3)2CO, dC) 27.7 (s, CH2 of cod); 47.1 (s, NCH3 cis to cod); 48.8
(s, NCH3 trans to cod); 78.6 (s, @CH of cod); 81.1 (s, @CH of cod);
88.6 (s, @CH of cod); 91.3 (s, @CH of cod). 31P{1H} NMR (ppm)
1
(162 MHz, CD2Cl2, dP) À144.3 (sp, JPF = 716 Hz, PF6). CHN (%):
[RuH(1,5-cod)(NH3)(NH2NMe2)2](PF6).H2O: C, 27.99 (28.23); H,
6.65 (6.71); N, 13.82 (13.72). 5: m.p.: >165 °C (decomposition
without melt). IR (
m
, cmÀ1): 3295 (
m
(NH), w); 3066 (
m(NH), w);
2918 ( (@CH), w); 2877 (
m
m
(NH), w); 2846 ( (–CH), m); 2158 (m);
m
1629 (d(NH), asym, w); 1571 (d(NH), asym, m); 1467 (d(–CH),
sym, m); 1408 (d(–CH), asym, m); 1363 (m); 1317 (m); (m);
1179 (d(NH), sym, w); 1163 (d(NH), sym, m); 1024 (m(CN), m);
2. Material and methods
978 (d(@CH), m); 904 (m(NN), m); 830 (m(PF), s); 556 (d(PF), s).
2.1. General
1H NMR (ppm) (400 MHz, (CD3)2CO, dH) 1.89 (br s, NH3, 2H); 2.30
3
(d, JHH = 7 Hz, CH2 of cod); 2.41–2.53 (m, CH2 of cod, 3H); 2.58–
All experiments were carried out under an Ar atmosphere using
standard Schlenk techniques. Solvents were dried using standard
techniques. The compound [RuCl2(1,5-cod)]x was prepared using
the literature procedure [26]. All other chemicals were purchased
from Sigma–Aldrich and used without further purification. 1H
(400 MHz), 13C{H} (101 MHz), 31P{H} (162 MHz) and 15N–1H
HMBC NMR spectra were recorded on a Bruker Avance III Ultra-
shield 400 MHz spectrometer fitted with a B-ACS 60 auto-sampler
using either CDCl3, CD2Cl2 or (CD3)2CO solutions. All measure-
ments were performed at ambient temperature (ꢀ296 K), unless
otherwise noted. Chemical shifts were referenced to the internal
residual protio impurities in the solvent (dH 7.24, 5.32, or
2.04 ppm in CDCl3, CD2Cl2, or (CD3)2CO respectively) or carbon sig-
nals (dH 77.0, 53.8, or 29.8 and 206.3 ppm in CDCl3, CD2Cl2, or
(CD3)2CO respectively). Solid state FT-IR experiments were carried
out on a Bruker Tensor 27 FT-IR as pressed KBr pellets in air. Melt-
ing points were performed in air on a Stuart SMP10 and are uncor-
rected. Microanalytical analyses (%CHNS) were performed at
Rhodes University (RSA) using an Elementar Vario Micro cube
instrument with a TCD detector. In cases where %Cl was required,
the analyses were performed externally at Galbraith Laboratories
(USA).
2.65 (m, CH2 of cod, 1H); 2.78 (s, NCH3, 6H); 3.33 (br s, NH3, 2H);
3
3.52 (d, JHH = 4 Hz, CH2 of cod, 1H); 3.84 (s, 1H); 4.07
3
3
(d, JHH = 7 Hz, CH2 and @CH of cod, 4H); 5.94 (d, JHH = 11 Hz,
@CH of cod, 1H); 6.82 (d, JHH = 12 Hz, @CH of cod, 1H). 13C{1H}
3
NMR (ppm) (101 MHz, (CD3)2CO, dC) 27.6 (s, CH2 of cod); 47.2
(s); 48.8 (s, NCH3); 78.4 (s, @CH of cod); 81.3 (s, @CH of cod);
88.6 (s, @CH of cod); 91.3 (s, @CH of cod). 31P{1H} NMR (ppm)
1
(162 MHz, (CD3)2CO, dP) À144.3 (sp, JPF = 708 Hz, PF6). CHN (%):
[RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6): C, 24.64 (24.82); H, 5.31
(5.42); N, 11.18 (11.58); Cl 7.54 (7.33).
2.3. Synthesis of [RuH(1,5-cod)(NH3)(NH2NMe2)2](BPh4) 4, and [RuCl
(1,5-cod)(NH3)2(NH2NMe2)](BPh4) 6
Similar to the syntheses of 1, 3, and 5, employing NaBPh4
instead of NH4PF6. Concentration of each extracted fraction gave
[RuH(1,5-cod)(NH2NMe2)3](BPh4) 2, from the (CH2Cl2 fraction,
light brown powder, 135 mg, 43%), 4 (CHCl3 fraction, brown pow-
der, 83 mg, 28%), and 6 (acetone fraction, beige powder, 39 mg,
13%). Characterisation data for 2 agrees with literature [16f]. 4:
m.p.: >142 °C (decomposition without melt). IR (
(NH), m); 3054 ( (NH), m); 3002 ( (@CH), w); 2870 (
w); 2831 ( (–CH), w); 2039 ( (RuH), w); 1602 (d(NH), asym, w);
m
, cmÀ1): 3127
(NH),
(m
m
m
m
m
m
2.2. Syntheses of [RuH(1,5-cod)(NH3)(NH2NMe2)2](PF6) 3 and [RuCl
(1,5-cod)(NH3)2(NH2NMe2)](PF6) 5
1579 (d(NH), asym, w); 1453 (d(–CH), sym, m); 1401 (d(–CH),
asym, s); 1387 (s); 1157 (d(NH), sym, w); 1095 (d(NH), sym, w);
1022 (
m); 706 (
m
(CN), m); 974 (d(@CH), w); 916 (
m
m(NN), w); 735 (m(BC),
A suspension of [RuCl2(1,5-cod)]x (0.497 g, 1.77 mmol) in MeOH
(8.0 mL) with NH2NMe2 (3.0 mL, 39.4 mmol) and H2O (0.75 mL)
was heated under reflux for 30 min, after which a filtered solution
of NH4PF6 (0.597 g, 3.7 mmol) in H2O (3.0 mL) was added. The
reaction mixture was concentrated in vacuo, filtered, and washed
with EtOH/Et2O from which an off-white microcrystalline solid
(0.218 g) was isolated. The crude product was extracted with CHCl3
(ꢀ15 mL), followed separately by CH2Cl2 (ꢀ15 mL), after which the
residue was extracted with acetone (ꢀ15 mL). Concentration of
each extracted fraction led to the isolation of the known [RuH
(1,5-cod)(NH2NH3)3](PF6) 1 (CHCl3 fraction, light brown microcrys-
tals, 62 mg, 26%), 3 (CH2Cl2 fraction, brown microcrystals, 47 mg,
22%), and 5 (acetone fraction, beige powder, 74 mg, 34%). Charac-
terisation for 1 is in agreement with literature [16f]. 3: m.p.:
(BC), m); 609 (m). 1H NMR (ppm) (400 MHz, CDCl3, dH)
3
À5.72 (s, RuH, 1H); 1.67 (m, H2O, 2H); 1.94 (d, JHH = 14 Hz, CH2
3
of cod, 1H); 2.07 (br s, NH3, 3H); 2.24 (t, JHH = 15 Hz, NCH3 trans
to cod, 6H); 2.41 (s, NCH3 cis to cod, 6H); 2.47 (s, CH2 of cod,
2H); 2.55 (d, JHH = 24 Hz, CH2 of cod, 2H); 2.96 (s, CH2 of cod,
1H); 3.53 (s, @CH of cod, 0.5H); 3.73 (s, @CH of cod, 0.5H); 4.05
3
3
3
(dd, JHH = 9 and 43 Hz, @CH of cod, 1H); 4.71 (dd, JHH = 10 and
3
44 Hz, @CH of cod, 1H); 5.12 (d, JHH = 10 Hz, @CH of cod, 0.5H);
5.27 (d, JHH = 10 Hz, @CH of cod, 0.5H); 5.81 (d, JHH = 10 Hz,
3
3
3
3
NH2, 2H); 6.90 (t, JHH = 7 Hz, C6H5, 4H); 7.04 (t, JHH = 7 Hz, C6H5,
8H); 7.41 (s, C6H5, 8H). 13C{1H} NMR (ppm) (75 MHz, CD2Cl2, dC)
3
26.2 (s, CH2 of cod); 28.5 (d, JCC = 34 Hz, CH2 of cod); 31.0 (s,
CH2 of cod); 33.1 (s, CH2 of cod); 48.8 (s, NCH3 trans to cod); 49.9
(s, NCH3 cis to cod); 88.1 (s, @CH of cod); 91.5 (s, @CH of cod);
3
>147 °C (decomposition without melt). IR (
3237 ( (NH), w); 3066 ( (NH), w); 2958 (
(NH), w); 2836 ( (–CH), m); 2789 (m); 2036 (
(d(NH), asym, m); 1459 (d(–CH), sym, m); 1406 (d(–CH), asym,
w); 1168 (d(NH), sym, m); 1151 (d(NH), sym, m); 1022 ( (CN),
(PF), s); 556 (d(PF),
m
, cmÀ1): 3375 (w);
(@CH), w); 2873
(RuH), w); 1607
122.4 (s, C6H5); 126.2 (d, JCC = 3 Hz, C6H5); 136.3 (s, C6H5), 164.4
m
m
m
(m, C6H5). 15N NMR (ppm) (51 MHz, (CD3)2CO, dN) 58 (s, NH3); 86
(s, NMe2); 106 (s, NMe2); 132 (s, NH2). CHN (%): [RuH(1,5-cod)
(NH3)(NH2NMe2)2](BPh4).3H2O: C, 60.13 (59.99); H, 7.76 (8.11);
(m
m
m
m
N, 9.44 (9.72). 6: m.p.: 142–144 °C. IR (
m); 3054 ( (NH), m); 3027 ( (@CH), w); 2867 (
(–CH), w); 1627 (d(NH), asym, w); 1596 (w); 1562 (d(NH),
m
, cmÀ1): 3127 (
(NH), w); 2845
m(NH),
m); 985 (d(@CH), m); 918 (
m
(NN), m); 830 (
m
m
m
m
s). 1H NMR (ppm) (400 MHz, CDCl3, dH) À5.58 (s, RuH, 1H); 1.23
(m

F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
135
asym, w); 1456 (d(–CH), sym, m); 1400 (d(–CH), asym, s); 1385 (s);
1152 (d(NH), sym, w); 1091 (d(NH), sym, w); 1030 ( (CN), m); 972
(d(@CH), w); 908 ( (NN), w); 802 (m); 736 ( (BC), m); 709 ( (BC),
m); 606 (m). 1H NMR (ppm) (400 MHz, (CD3)2CO, dH) 1.79
2.6. Synthesis of fac-[RuCl(NH3)2(PMe2Ph)3](PF6) (12)
m
m
m
m
To a brown solution of [RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6)
(5) (2.367 g, 4.9 mmol) in MeOH (40 mL) was added PMe2Ph
(2.4 mL, 16.9 mmol) and the resulting reaction mixture was heated
under reflux for 1 h. After cooling the yellow crystalline product
was filtered and washed with EtOH (5 mL) and Et2O (5 mL) from
which the title compound was isolated as deep yellow cuboid crys-
3
3
(q, JHH = 8 Hz, CH2 of cod); 1.92 (s, NH3, 1H); 2.25 (d, JHH = 12 Hz,
3
CH2 of cod, 1H); 2.31 (s, CH2 of cod, 2H); 2.49 (t, JHH = 8 Hz, CH2
of cod, 2H); 2.60 (s, NCH3, 6H); 3.04 (m, CH2 of cod, 1H); 3.83
3
(s, @CH of cod, 1H); 4.01 (t, JHH = 7 Hz, @CH of cod, 2H); 4.12
3
(s, @CH of cod, 1H); 4.46 (br s, NH3, 2H); 5.56 (d, JHH = 11 Hz,
tals (1.289 g, 36%). m.p.: 156–158 °C. IR (
m
, cmÀ1): 3371 (
(–CH), m); 2924 (w);
m(NH), m);
3
1H); 5.99 (m, NH2, 1H); 6.77 (t, JHH = 7 Hz, C6H5, 4H); 6.92
3346 ( (NH), w); 3060 ( (@CH), w); 2987 (m
m
m
3
(t, JHH = 7 Hz, C6H5, 8H); 7.33 (s, C6H5, 8H). 13C{1H} NMR (ppm)
1829 (w); 1617 (d(NH), asym, s); 1482 (m); 1433 (d(–CH), sym,
s); 1405 (d(–CH), asym, s); 1288 (s); 1262 (s); 1222 (d(@CH), s);
1100 (d(NH), sym, m); 1051 (m); 1000 (d(@CH), w); 945 (s); 904
(101 MHz, CD2Cl2, dC) 28.7 (s, CH2 of cod); 33.2 (s, CH2 of cod);
48.8 (s, NCH3 trans to cod); 64.7 (s, @CH of cod); 70.3 (s, @CH of
3
cod); 122.2 (s, C6H5); 126.0 (q, JCC = 2 Hz, C6H5); 136.4 (s, C6H5);
(s); 869 (d(para @CH), s); 839 (m(PF), s); 749 (d(ortho @CH), s);
164.5 (m, C6H5). 15N NMR (ppm) (51 MHz, (CD3)2CO, dN) À18
(s, NH3); 57 (s, NMe2); 69 (s, NMe2); 116 (s, NH2); 344 (s). CHN
(%): [RuCl(1,5-cod)(NH3)2(NH2NMe2)](BPh4).H2O: C, 60.39 (60.40);
H, 7.44 (7.16); N, 9.49 (9.29).
703 (s); 677 (d(meta @CH), s); 556 (d(PF), s). 1H NMR (ppm)
(400 MHz, (CD3)2CO, dH) 1.11 (t, JHH = 7 Hz, CH3CH2OH, 1H); 1.73
(d, JHH = 8 Hz, P(CH3)2, 6H); 1.75 (s, NH3, 3H); 1.96 (t, JHH = 4 Hz,
P(CH3)2, 6H); 2.01 (d, JHH = 4 Hz, P(CH3)2, 3H); 2.08 (s, P(CH3)2,
3H); 3.30 (s, NH3, 3H); 3.55 (s, CH3OH, 1H); 7.27–7.35 (m, P
(C6H5), 4H); 7.46 (d, JHH = 7 Hz, P(C6H5), 6H); 7.62 (s, P(C6H5),
5H). 13C{1H} NMR (ppm) (101 MHz, CDCl3, dC) 17.9 (s, P(CH3)2);
18.2 (s, P(CH3)2); 18.4 (s, P(CH3)2); 18.7 (m, P(CH3)2); 128.9 (t,
2.4. Synthesis of [{Ru(PMe2Ph)3}2(l-F)3](PF6) (10)
3
3JCC = 4 Hz, P(C6H5)); 129.2 (t, JCC = 4 Hz, P(C6H5)); 129.4 (d,
To a dark yellow solution of cis- and trans-[RuH2(PMe2Ph)4]
(PF6) [30] (2.856 g, 4.4 mmol) in EtOH (60 mL) was added PMePh2
(0.6 mL, 4.2 mmol) and HPF6 (0.8 mL, 9.0 mmol) and the resulting
reaction mixture was heated under reflux for 2 h. After cooling,
the clear light yellow solution was filtered using vacuum filtration,
and washed with EtOH (5 mL) and Et2O (10 mL) to give a light yel-
low powder. This was recrystallized as light yellow needles using
3JCC = 9 Hz, P(C6H5)); 129.8 (s, P(C6H5)); 129.9 (s, P(C6H5)); 136.6
(d, 3JCC = 45 Hz, P(C6H5)). 31P{1H} NMR (ppm) (162 MHz, (CD3)2CO,
1
2
dP) À144.2 (sp, JPF = 708 Hz, PF6); 19.2 (d, JPP = 34 Hz, PMe2Ph cis
to equatorial NH3); 25.9 (t, 2JPP = 32 Hz, PMe2Ph trans to equatorial
NH3). 15N NMR (ppm) (51 MHz, CDCl3, dN) À8 (s, NH3). CHN (%):
[RuCl(NH3)2(PMe2Ph)3](PF6).0.5EtOH: C, 39.26 (39.87); H, 6.70
(5.62); N, 3.37 (3.72).
CH2Cl2/EtOH (2.314 g, 43%). m.p.: 212–214 °C. IR (
m
, cmÀ1): 3137
(C@C),
(m
(@CH), m); 3057 ( (@CH), w); 3001 ( (–CH), m); 1619 (m
m
m
2.7. Synthesis of [RuCl(NH3)(PMe2Ph)4](PF6) (13)
w); 1486 (m); 1432 (d(–CH), sym, s); 1402 (d(–CH), asym, s);
1296 (d(@CH), m); 1277 (d(@CH), m); 1100 (s); 938 (d(@CH), s);
To a brown solution of [RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6)
(5) (2.228 g, 4.6 mmol) in MeOH (50 mL) was added PMe2Ph
(3.0 mL, 21.1 mmol) and heated under reflux for 1 h. After cooling,
yellow crystals formed from the clear reddish-brown solution and
was filtered, washed with MeOH (10 mL) and Et2O (10 mL) to give
903 (d(para @CH), s); 839 (m(PF), s); 747 (d(ortho @CH), s); 702 (d
(–CH), s); 676 (d(meta @CH), s); 557 (d(PF), s). 1H NMR (ppm)
(400 MHz, (CD3)2CO, dH) 1.49 (br s, P(CH3), 36H); 7.55 (m, P
(C6H5), 18H); 8.28 (m, P(C6H5), 12H). 13C{1H} NMR (ppm)
(101 MHz, CDCl3, dC) 17.7 (s, P(CH3)); 18.4 (s, P(CH3)); 128.6 (t,
light yellow cuboid crystals (1.641 g, 42%). m.p.: 175–177 °C. IR (
cmÀ1): 3365 (
(NH), w); 3056 ( (@CH), w); 2988 ( (–CH), w); 1608
(d(NH), asym, m); 1595 ( (C@C), w); 1484 (m); 1436 (d(–CH), sym,
m); 1412 (d(–CH), asym, m); 1317 (m); 1239 (d(@CH), m); 1095 (d
(NH), sym, w); 943 (m); 897 (d(para @CH), s); 831 ( (PF), s); 760
m,
2
2JCC = 140 Hz, P(C6H5)); 129.5 (d, JCC = 27 Hz, P(C6H5)); 131.1 (s, P
m
m
m
(C6H5)). 31P{1H} NMR (ppm) (162 MHz, CDCl3, dP) À144.3 (sp,
m
1
2
1JPF = 713 Hz, PF6); 33.9 (ddd, JPP = 171 Hz and JPP = 36 and
88 Hz, PMe2Ph). CHN (%): [{Ru(PMe2Ph)3}2(l-F)3](PF6): C, 46.87
(46.76); H, 5.40 (5.40); N, 0.00 (0.00).
m
(m); 744 (d(ortho @CH), s); 725 (m); 703 (d(–CH), s); 676 (d(meta
@CH), s); 556 (d(PF), s). 1H NMR (ppm) (400 MHz, CD2Cl2, dH)
0.32 (br s, NH3, 3H); 1.19 (s, P(CH3)2 trans to Cl, 6H); 1.93 (s, P
3
2.5. Synthesis of [RuCl(NH3)2(PMe3)3](PF6) (11)
(CH3)2 cis to Cl, 9H); 1.98 (q, JHH = 8 Hz, P(CH3)2 cis to Cl, 9H);
7.20 (m, P(C6H5), 2H); 7.32 (s, P(C6H5), 10H); 7.47 (s, P(C6H5),
3H); 7.55–7.65 (m, P(C6H5), 5H). 13C{1H} NMR (ppm) (101 MHz,
CDCl3, dC) 16.0 (t, 2JCC = 29 Hz, P(CH3)2 cis to Cl); 21.6 (d, 2JCC = 30 -
Hz, P(CH3)2 cis to Cl); 23.5 (s, P(CH3)2 trans to Cl); 129.5 (s, P
To a brown solution of [RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6)
(5) (1.057 g, 2.2 mmol) in EtOH (30 mL) was added PMe3 (0.8 mL,
7.8 mmol) and the resulting reaction mixture was heated under
reflux for 1 h. The dark brown solution was concentrated, filtered,
and washed with EtOH (10 mL) and Et2O (10 mL) from which a
blue–green precipitate was isolated. Recrystallisation using ace-
tone/EtOH gave a dark blue powder (0.456 g, 38%). m.p.: >300 °C
3
(C6H5)); 129.7 (m, P(C6H5)); 130.5 (d, JCC = 23 Hz, P(C6H5)); 130.8
3
(d, JCC = 20 Hz, P(C6H5)). 31P{1H} NMR (ppm) (162 MHz, CD2Cl2,
1
2
dP) À144.5 (sp, JPF = 711 Hz, PF6); À1.2 (t, JPP = 30 Hz, PMe2Ph
2
trans to NH3); 11.7 (q, JPP = 32 Hz, PMe2Ph cis to NH3); 15.3 (q,
(decomposition without melt). IR (
3303 ( (NH), w); 2981 ( (–CH), w); 2924 (
(NH), asym, m); 1435 (d(–CH), sym, m); 1311 (m); 1298 (m);
m
, cmÀ1): 3367 (
(–CH), w); 1626 (d
m
(NH), w);
2JPP = 28 Hz, PMe2Ph trans to Cl). 15N NMR (ppm) (51 MHz, CDCl3,
dN) À7 (s, NH3). CHN (%): [RuCl(NH3)(PMe2Ph)4](PF6): C, 45.04
(45.16); H, 5.73 (5.57); N, 1.64 (1.65).
m
m
m
1130 (d(NH), sym, w); 947 (m); 828 (m(PF), s); 739 (m); 672 (d(–
CH), m); 556 (d(PF), s). 1H NMR (ppm) (400 MHz, (CD3)2CO, dH)
1.56 (m, P(CH3)3, 27H); 2.08 (br s, NH3, 2H); 3.30 (br s, NH3, 2H).
2.8. X-ray crystallography of compounds 8, 9, 10, 12, and 13
3
13C{1H} NMR (ppm) (101 MHz, (CD3)2CO, dC) 20.1 (t, JCC = 20 Hz,
Single crystals of compounds 8, 9, 10, 12, and 13 were mounted
on a fine glass rod and diffracted with graphite-monochromated
Mo Ka radiation (k = 0.71069 Å) using a Bruker APEX-II CCD area-
detector diffractometer. X-ray diffraction measurements were
P(CH3)3); 49.6 (s). 31P{1H} NMR (ppm)(162 MHz, (CD3)2CO, dP)
1
À144.3 (sp, JPF = 708 Hz, PF6); 20.8 (s, PMe3); 22.4 ppm (d,
2JPP = 24 Hz, PMe3). CHN (%): [RuCl(NH3)2(PMe3)3](PF6): C, 19.98
(19.88); H, 5.90 (6.12); N, 4.95 (5.15).
made at 293(2) K (8), 293(2) K (9), 100(1) K (10), 150(2) K (12),

136
F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
and 293(2) K (13). Absorption corrections were carried out using
SADABS [27]. All structures were solved by direct methods with
SHELXS-97 [28] using the OLEX2 [29] interface. All H atoms were
placed in geometrically idealised positions and constrained to ride
on their parent atoms. Crystal data and experimental parameters
for complexes 8, 9, 10, 12, and 13 are given in Table 1.
3. Results and discussion
3.1. Synthesis of hydrido- and chlorido-ammine-Ru(II) complexes
Due to the interest in the highly reactive synthetic precursor
[RuH(1,5-cod)(NH2NMe2)3](PF6) during the years of 1977–1986, a
number of by-products in the preparative reactions of the latter
complex were missed or simply not further investigated [16].
The complex [RuH(1,5-cod)(NH2NMe2)3](PF6) was mainly
employed as a synthon to a vast range of catalytically active Ru
(II) and Ru(IV) complexes, for which access to vacant coordination
sites at the metal centre is readily obtained through NH2NMe2 and/
or 1,5-cod ligand dissociation [16–18]. However, the formation of
Ru(II)-ammine species from reactions involving Ru(II)-NH2NMe2
and NH4PF6/NaBPh4 salts in our laboratories lead us to reinvesti-
gate the known reaction of the polymeric [RuCl2(1,5-cod)]x and
NH2NMe2, and the synthetic and catalytic properties that these
novel Ru(II)-ammine complexes may exhibit.
The known [16f] reaction involves heating a methanol slurry of
the polymer with 6 equivalents of NH2NMe2 in the presence of H2O
for 30 min, after which anion exchange with NH4PF6 (in H2O) or
NaBPh4 (in MeOH) occurs. Concentration of the resulting
solutions gave beige microcrystalline precipitates, from which in
both cases three products were isolated (Scheme 1). Extraction of
both the PF6- and BPh4-salts with CHCl3 followed by CH2Cl2, and
finally acetone gave the following complexes respectively:
fac-[RuH(1,5-cod)(NH2NMe2)3](PF6) (1) (known), [RuH(1,5-cod)(NH3)
(NH2NMe2)2](PF6) (3) (novel), and [RuCl(1,5-cod)(NH3)2(NH2NMe2)]-
(PF6) (5) (novel); and the complexes [RuH(1,5-cod)(NH3)
(NH2NMe2)2](BPh4) (4) (novel), fac-[RuH(1,5-cod)(NH2NMe2)3]
(BPh4) (2) (known), and [RuCl(1,5-cod)(NH3)2(NH2NMe2)](BPh4)
(6) (novel).
Scheme 2. The Chatt cycle [5a] derived for methyldiazene and N,N-
dimethylhydrazine counterparts in the N2 reduction process.
been reported [1e,24b,30]. This is the first reported instance of
the catalytic decomposition of NH2NMe2 by Ru(II), and forms
some of the first examples where NH2NMe2 Ru(II)-ammine
intermediate complexes are isolated in the N2 and methyldiazene
activation routes [15]. Another source for the formed NH3 is the
conjugated acid-base pairs NH3 and HPF6 from the aqueous NH4PF6
salt employed. The in situ formation of NH3 as ligand specifically in
Ru(II) systems are rather common, as cited in reports involving the
use of NH4PF6, where it is used in the activation of ammonia and
the formation of alkynylamine [4a,14,31]. The complexes [RuH
(1,5-cod)(NH3)(NH2NMe2)2](BPh4)
(2)
and
[RuCl(1,5-cod)
(NH3)2(NH2NMe2)](BPh4) (6) were isolated, albeit in low yields,
in the absence of any external source of NH3 which indicates
NH2NMe2
decomposition.
Complexes
[RuH(1,5-cod)(NH3)
(NH2NMe2)2](PF6) (3) and [RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6)
(5) were isolated in higher yields due to the combined effect of
NH2NMe2 decomposition and the conjugated base pair formation
from NH4PF6. We found that when >1.8 M equivalents of NH4PF6
is used, an increase in the formation of 3 and 5 is observed,
suggesting the NH4PF6 salt does play a major role in the in situ
formation of NH3.
The steric requirements of a coordinated chloride-ion together
with three relatively bulky NH2NMe2 ligands may drive the mole-
cule to react either by conversion to the smaller hydride ligand
through an intermolecular hydride formation mechanism using
MeOH, or through a catalytic decomposition of a NH2NMe2 ligand
to form NH3. Attempts to convert the chlorido-ammine complexes
5 and 6 into the hydrido-ammine complexes 3 and 4 respectively
by the reactions of excess NH2NMe2 in MeOH failed. However,
upon heating reaction mixtures containing 3 and 4 with an excess
of NH2NMe2 in MeOH, complexes 1 and 2 are eventually obtained,
albeit in low yields (ꢀ30%).
To the best of our knowledge, complexes 5 and 6 are the first
reported chloro-cyclooctadiene bis-ammine ruthenium(II) com-
plexes. The appearance of NH3 as a coordinated ligand in these
reactions from [RuCl2(1,5-cod)]x and NH2NMe2 is proposed to have
two sources. The first is the catalytic decomposition, or nitrogenase
[24b,30], of a molecule of NH2NMe2 to form NH3 and HNMe2 as by-
products (Scheme 2). The catalysed decomposition of NH2NH2 in
particular is well-documented, and only one report on the
decomposition of phenylhydrazine as a substituted hydrazine has
Scheme 1. Synthesis of NH2NMe2–Ru(II) complexes from the polymeric [RuCl2(1,5-cod)]x.

F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
137
The 1H NMR spectrum of 3 contains a singlet assigned to the
Ru–H at dH À5.58, signals for NH2NMe2 in a 1:1 ratio at dH 2.44
(NMe trans to 1,5-cod) and 2.73 (NMe cis to 1,5-cod) ppm respec-
tively, and a broad singlet at dH 1.23 for the NH3 proton. The 1H
NMR spectrum of 5 showed two broad singlets at dH 1.89 and
3.33 for the protons of two NH3 in chemically different environ-
ments. The 1H- and 13C{1H} NMR spectra for the BPh4-anion ana-
logues (2, 4, and 6) were generally comparable to the PF6-anion
analogues.
The reaction of [RuH(1,5-cod)(NH2NMe2)3](X) (1) or [RuH(1,5-
cod)(NH3)(NH2NMe2)2](PF6) (2) with excess PMePh2 in EtOH, gave
light yellow crystals of the known complex cis-[RuH2(PMePh2)4]
(9), whose molecular structure is unknown. As the intraligand
repulsion of the bulkier phosphine ligands is increased, the ten-
dency for halide ligand substitution by hydride ligands increases,
and therefore suggests a steric-controlled outcome in these reac-
tions (Scheme 3) [32].
The molecular structure of 9 shows three phosphine ligands (P1,
P2, P4) coordinated to the ruthenium atom in the same (equatorial)
plane, with the fourth phosphine ligand (P3) occupying the apical
position trans to one apical hydride ligand (H1b) (Fig. 2). The equa-
torial plane itself is disordered, with P1–Ru1–P2 = 146.41(2)°, and
H1a–Ru1–P4 = 172.33(2)°, both deviating from the ideal 180°
expected (Table 2). Significant folding in of P1 and P2 towards
the smaller hydrido atom is observed with angles H1a–Ru1–
P1 = 80.34(2)°, and H1a–Ru1–P2 = 77.90(2)°. H1a is coordinated
in an equatorial plane with three phosphine ligands, resulting in
a shorter Ru–H bond length (Ru1–H1a = 1.5943(4) Å), as compared
to H1b (Ru1–H1b 1.6479(5) Å).
3.2. Reactions of [RuH(1,5-cod)(NH2NMe2)3](A) (A = PF6, 1; BPh4, 2)
The majority of the following reactions described in this section
are known reactions that lead to methyldiazene activation inter-
mediates that have not been identified or fully characterised
before. The reaction of the complexes [RuH(1,5-cod)(NH2NMe2)3]
(X) (X = PF6, 1; BPh4, 2) with 5.2 equivalents of P(OMe)2Ph in boil-
ing MeOH under a N2 atmosphere gave the known complexes [RuH
{P(OMe)2Ph}5](X) (X = PF6, 7; BPh4, 8) in high yields (86% for 7, 88%
for 8). Upon employing the slightly larger PMe2Ph ligand the known
complexes [RuH(1,5-cod)(PMe2Ph)3](PF6) and [RuH(PMe2Ph)5](PF6)
were isolated under similar reaction conditions [16a,d].
The unknown molecular structure of complex 8 shows a slightly
distorted octahedron of the cation with five coordinated P(OMe)2-
Ph ligands, four in the same equatorial plane, and the fifth in the
apical position, trans to the hydride ligand (Fig. 1). With the
hydride ligand in the apical position, a structural trans-influence
of the hydride ligand on the trans-coordinated P13 ligand is
expected although the Ru1–P13 bond (2.3408(2) Å), is only the
second longest Ru-P bond observed. The bond angles of P11–
Ru1–P14 = 177.067(2)°, and P12–Ru1–P15 = 159.174(1)° are
indicative of the inherent distortion (Table 2). The ligands P12
and P15 show a degree of folding towards the smaller hydride
ligand, as indicated by the P12–Ru1–P15 bond angle as well as
the bond angles P12–Ru1–H1 = 80.221(1)° and P15–Ru1–
H1 = 78.977(1)°.
In an attempt to convert the dihydrido complexes [RuH2(L)4]
(L = PMe2Ph, PMePh2) into the monohydrido complexes [RuH(L)5]
(PF6), the complex [RuH2(PMe2Ph)4] [32a] was reacted with 2
equivalents each of both HPF6 and PMe2Ph under reflux. The
known
dimeric
triply
fluoro-bridged
complex,
[{Ru
(PMe2Ph)3}2(
l
-F)3](PF6) (10), was isolated in moderate yields
(43%). The labilization of fluoride ions from a PFÀ6 source to form
triply-bridged fluoride dimers is not uncommon, and has been
reported for the reactions of [RuH(1,5-cod)(NH2NMe2)3](A)
(A = PF6, BPh4) with PMe2Ph in acetone/methanol mixtures in the
presence of H2O, H2S, HSMe, or HF to give [{Ru(PMe2Ph)3}2(l-
X)3](A) (A = PF6, BPh4, X = OH, F, SH, SMe) [16g,33a]. These
reactions occur due to the minimisation of intraligand strain, and
the overall stabilization of ruthenium(II) complexes by anionic-
bridges [33].
The 31P NMR of 10 shows a single multiplet at dP 33.9 (ddd,
1JPP = 171 Hz and 2JPP = 36 and 88 Hz) for symmetrical arrangement
Table 1
Crystal data and experimental parameters for complexes 8, 9, 10, 12, and 13.
Complex
8
9
10
12
13
Emp. formula
Formula weight (g molÀ1
Crystal system
Space group
Crystal descr.
Crystal size (mm)
a (Å)
C
128H152B2O20P10Ru2 C52H54P4Ru
C48H66F9P7Ru2
1232.93
monoclinic
C2/c
C25H42ClF6N2O0.5P4Ru C32H47ClF6NP5Ru
)
2543.95
orthorhombic
Pca21
903.90
monoclinic
P21/n
753.00
851.07
monoclinic
P21/c
monoclinic
P21/n
Brown prism
Yellow cuboid
Yellow needle
Orange needle
Yellow cuboid
0.223 Â 0.129 Â 0.126
16.367(3)
12.042(5)
20.301(0)
90.000
0.331 Â 0.162 Â 0.08 0.342 Â 0.216 Â 0.179 0.365 Â 0.080 Â 0.074 0.385 Â 0.24 Â 0.182
28.469(4)
11.957(3)
36.635(5)
90.000
9.903(1)
38.116(2)
11.667(1)
90.000
31.3480(2)
16.3711(8)
28.4795(2)
90.000
10.1732(1)
19.072(2)
17.343(2)
90.000
b (Å)
c (Å)
a
(°)
b (°)
90.000
90.000
12,471(4)
4
1.355
90.702(5)
90.000
4404.3(6)
4
1.363
0.537
121.8850(1)
90.000
12410.3(1)
8
1.320
0.844
105.483(5)
90.000
3242.8(7)
4
1.542
0.819
113.035(1)
90.000
3682(2)
c
(°)
V (Å3)
Z
4
Dcalc (mg mÀ3
)
1.535
0.771
1744.0
Abs. coefficient (m mmÀ1
F(000)
)
0.437
5312.0
1880.0
5024.0
1540.0
2h range (°)
Independent reflections
4.312–41.66
28,752
2.136–56.98
11,092
1.68–56.76
15,481
4.672–67.566
7465
2.73–50.086
6398
Index ranges
À37 6 h 6 37
À15 6 k 6 15
À47 6 l 6 47
99.7
Multi-scan
13,027/1/1487
1.050
À13 6 h 6 13
À50 6 k 6 50
À15 6 l 6 15
99.3
Multi-scan
11,092/0/526
1.097
À41 6 h 6 41
À21 6 k 6 21
À38 6 l 6 37
99.5
Multi-scan
15,481/0/607
1.008
À13 6 h 6 13
À24 6 k 6 24
À22 6 l 6 22
99.9
Multi-scan
12,982/0/398
1.080
À15 6 h 6 19
À13 6 k 6 14
À24 6 l 6 24
98.0
Multi-scan
6398/0/433
1.060
Completeness (%)
Abs. corr. method
Data/restraints/parameter
Goodness-of-fit (GOF) on F2
Final R1 indices
0.0278
0.0292
0.0410
0.0302
0.0259
wR2 indices (all data)
0.0619
0.53 and À0.24
0.0719
0.42 and À0.39
0.1096
0.67 and À0.75
0.0787
1.11 and À0.69
0.0585
0.35 and À0.47
Largest difference in peak and hole (e ÅÀ3
)

138
F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
Fig. 1. (a) Molecular diagram of [RuH{P(OMe)2Ph}5](BPh4) (8), with thermal ellipsoids drawn at 50% probability level. Hydrogen atoms (apart from the hydride ligand) are
omitted for clarity.
of the PMe2Ph ligands around each ruthenium centre. The Ru1–
Ru2 interatomic distance of 3.1097(4) Å is slightly longer than that
3.3. Reactions of [RuCl(1,5-cod)(NH3)2(NH2NMe2)](PF6) (5)
reported for [{Ru(PMe2Ph)3}2(
pares well with the complex [{Ru(PEt)3}2(
(4) Å] (Table 2) [33a]. Three equivalent PMe2Ph ligands are fac-
coordinated to each ruthenium centre, with typical Ru–P bond
lengths varying between 2.2413(9)–2.2474(8) Å, which is slightly
shorter than the reported Ru-P bond lengths for the similar [{Ru
l
-OH)3](BPh4) (3.08 Å), but com-
-F)3](CF3SO3) [3.1081
Contrasting to the reactions of 1–4 bearing hydride moieties
that are known, reactions of the novel chlorido-Ru(II)–ammine
complexes results in the isolation of novel chloride methyldiazene
and ammine intermediates. Reaction of [RuCl(1,5-cod)(NH3)2
(NH2NMe2)3](PF6) (5) with 3.5 equivalents of PMe3 in boiling
MeOH gave [RuCl(NH3)2(PMe3)3](PF6) (11) and the known dimeric
l
(PEt)3}2(l-F)3](CF3SO3) complex (Fig. 3) [33a].
complex [{Ru(PMe3)3}2(l-Cl)3]. Recrystallization of the mixture
Table 2
Selected bond distances (Å) and angles (°) for complexes 8, 9, and 10.
8
9
10
Ru1–P11
Ru1–P12
Ru1–P13
Ru1–P14
Ru1–P15
Ru1–H1
B1–CA1
B1–CA7
P11–Ru1–P12
P11–Ru1–P13
P11–Ru1–P14
P12–Ru1–P15
P14–Ru1–P15
H1–Ru1–P12
H1–Ru1–P13
H1–Ru1–P15
Ru1–P13–O131
Ru1–P13–O132
2.3258(2)
2.3111(1)
2.3409(9)
2.3427(1)
2.3142(9)
1.4987(2)
1.648(5)
1.649(6)
91.27(4)
90.84(3)
177.08(4)
159.14(3)
89.76(3)
80.22(5)
179.46(5)
78.98(5)
108.70(1)
113.20(1)
Ru1–P1
Ru1–P2
Ru1–P3
Ru1–P4
Ru1–H1a
Ru1–H1b
H1a–Ru1–H1b
H1a–Ru1–P1
H1a–Ru1–P2
H1a–Ru1–P3
H1b–Ru1–P1
H1b–Ru1–P4
P1–Ru1–P2
P1–Ru1–P3
P1–Ru1–P4
P2–Ru1–P3
P2–Ru1–P4
P3–Ru1–P4
2.3038(8)
2.3050(7)
2.3675(9)
2.3390(7)
1.5943(4)
1.6479(5)
87.31(2)
80.34(2)
77.90(2)
87.59(2)
72.24(2)
86.46(2)
146.41(2)
106.83(3)
101.97(3)
97.52(3)
96.72(3)
98.62(3)
Ru1–Ru2
Ru1–P11
Ru1–P12
Ru1–P13
Ru2–P21
Ru2–P22
Ru2–P23
Ru1–F1
3.1097(4)
2.2425(8)
2.2460(8)
2.2432(8)
2.2413(9)
2.2430(8)
2.2474(8)
2.1345(2)
2.1372(2)
2.1528(2)
93.30(6)
93.58(7)
92.87(6)
95.67(3)
93.77(3)
93.44(3)
95.73(3)
93.49(3)
Ru1–F2
Ru1–F3
Ru1–F1–Ru2
Ru1–F2–Ru2
Ru1–F3–Ru2
P11–Ru1–P12
P11–Ru1–P13
P12–Ru1–P13
P21–Ru2–P22
P21–Ru2–P23
Scheme 3. Syntheses of [RuHL1](X) and [RuH2(L2)4] species using different L1 = PMe3, PMe2Ph, P(OMe)2Ph, and L2 = PMe2Ph, PMePh2 phosphines.

F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
139
the reaction of [RuCl(1,5-cod)(NH3)2(NH2NMe2)3](PF6) (5) with 4
equivalents of PMe2Ph, one molecule of NH3 dissociates (in addi-
tion to NH2NMe2 and 1,5-cod) to give [RuCl(NH3)(PMe2Ph)4](PF6)
(13) (Scheme 4). It has been found that 12 may be converted to
13 by reaction of an additional equivalent of PMe2Ph. The 1H
NMR spectrum of 12 exhibits two distinct NH3 singlets at dH 1.75
and 3.30, indicating that each of these ligands occupies a different
chemical environment, whereas a single broad singlet at dH 0.32
was observed for the NH3 ligand in 13. The 15N–1H HMBC NMR
spectra of 4 and 6 both showed similar signals for the non-equiv-
alent ammine ligands at dN 58 (4) and À18 (6). Other typical 15N
resonances observed included those of the NH2NMe2 ligands,
which were similar for all the complexes around dN 57–69
(NMe2), 86–106 (NMe2) and 116–132 (NH2). The ammine signals
shifted in the phosphine-substituted complexes 12 and 13, with
signals resonating at dN À8 (two doublets for non-equivalent NH3
ligands) (12), and dN À7 (one doublet for a single NH3 ligand) (13).
Addition of a few drops of D2O to (CD3)2CO solutions of both 5
and 13 bearing NH3 moieties resulted in the disappearance of the
NH3 proton signals. Both 2D COSY 1H–1H and 15N–1H HMBC spec-
tra also showed no coupling between the D2O and NH3 signals,
which indicate spontaneous exchange of the Ru-NH3 and Ru-OD2
species, as opposed to Ru–NH3 and Ru–ND3 exchange. The 31P
NMR spectrum of 12 revealed three PMe2Ph ligands in two chem-
Fig. 2. (a) Molecular diagram of cis-[RuH2(PMePh2)4] (9), with thermal ellipsoids
drawn at 50% probability level. Hydrogen atoms (apart from the hydride ligands)
are omitted for clarity.
2
yielded 11 as a dark blue powder in low yield (38%), which was dif-
ficult to analyse. It is concluded that dimerization is a secondary
reaction occurring after the formation of 11, possibly due to the
stabilization effect brought about by the halogen bridges. The 1H
NMR spectrum shows two unique broad singlets for the cis NH3
ligands at dH 2.08 and 3.30 ppm. The presence of the PMe3 ligands
in two unique chemical environments are shown in the NMR spec-
tra of 11: a multiplet at dH 1.56 in the 1H NMR spectrum; two sig-
ically unique environments: dP 19.2 (d, JPP = 34 Hz) and 25.9
2
(t, JPP = 32 Hz); whereas for 13 signals for four PMe2Ph in three
chemically different environments were observed: dP À1.2
(t, 2JPP = 30 Hz, PMe2Ph trans to NH3); 11.7 (q, 2JPP = 32 Hz, PMe2Ph
2
cis to NH3); 15.3 (q, JPP = 28 Hz, PMe2Ph trans to Cl).
The complex [RuCl(NH3)(PMe2Ph)4](PF6) (13), exhibits only one
NH3 ligand in the equatorial position, along with three PMe2Ph
ligands in the same plane. In both 12 and 13 the chlorido-ligand
is coordinated cis to the equatorial NH3 ligand, along with two
other PMe2Ph ligands (Figs. 4 and 5). In 12, the bond angles N1–
Ru1–P2 (170.40(5)°), Cl1–Ru1–P1 (170.28(2)°), and N2–Ru1–P3
(169.85(6)°) all show distortion along the apical plane (Table 3).
The relative degree of steric strain in the equatorial plane of the
complex brought about by phosphines P1 and P3 is illustrated in
the increased P1–Ru1–P3 bonding angle of 96.25(2)°, together with
3
nals at dC 20.1 (t, JCC = 20 Hz) and 49.6 (s) in the 13C NMR
spectrum; and two resonances at dP 20.8 (s) and 22.4 (d, 2JPP = 24 -
Hz) in the 31P NMR spectrum.
Upon reacting 5 with 3 equivalents of PMe2Ph in MeOH,
fac-[RuCl(NH3)2(PMe2Ph)3](PF6) (12) was isolated as deep yellow
crystals. Both NH3 ligands remained coordinated to the ruthenium
centre, similar to the analogous [RuCl(NH3)2(PMe3)3](PF6) (11). In
Fig. 3. Molecular diagram of [{Ru(PMePh2)3}2(l-F)3](PF6) (10), with thermal ellipsoids drawn at 50% probability level. Hydrogen atoms are omitted for clarity.

140
F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
Scheme 4. Syntheses of mono- and bis-ammine Ru(II)-PMe2Ph complexes.
the smaller Cl1–Ru1–P3 and P1–Ru1–N2 angles of 91.61(2)° and
92.82(6)° respectively. The folding in of Cl and N2 due to the pres-
ence of P1 and P3 results in the significantly smaller Cl1–Ru1–N2
bonding angle of 78.92(6)°. The degree of resulting intraligand
repulsion increased in 13 due to an additional PMe2Ph ligand.
This was evident in the equatorial plane, where the reduced Cl1–
Ru1–P1 and Cl1–Ru1–P4 bond angles of 84.41(3)° and 80.82(3)°,
respectively were observed. The folding in of the substituents of
P1 and P4 towards Cl1 resulted directly in the increased P1–Ru1–
P3 and P3–Ru1–P4 bond angles of 92.91(3)° and 101.18(3)°,
respectively.
3.4. 1H NMR spectrometry of successive PMe3 additions
In light of the reactions of complexes 1–4 with phosphines and
phosphonites to form the cationic [RuH(P)5]+ and related species,
we were interested in the ligand substitution route followed and
how it agrees with our steric-controlled reaction outcomes. Firstly,
it is known that the complexes [RuH(1,5-cod)(NH2NMe2)3](X)
(X = PF6, 1; BPh4, 2) reacts with 3 equivalents of phosphines
(P = P(OMe)3, PMe3, PMe2Ph, PMePh2) to form the complexes
[RuH(1,5-cod)(P)3](X) (X = PF6, BPh4). These complexes react fur-
ther with excess phosphine to substitute the diene ligand to pro-
duce the complexes [RuH(P)5](X) (X = PF6, BPh4). An acetone-d6
solution of [RuH(1,5-cod)(NH2NMe2)3](BPh4) (2) shows a hydride
Fig. 5. Molecular diagram of [RuCl(NH3)(PMePh2)4](PF6) (13). Thermal ellipsoids
were drawn at 50% probability level, and hydrogen atoms (apart from the NH3
ligand) are omitted for clarity.
signal in the 1H NMR spectrum at À5.28 ppm, which upon addition
of 1 M equivalent of PMe3 resolves to 6 different hydride singlets of
variable intensities (Scheme 5). This is ascribed to a mixture of
complexes resulting from the mono-substitution of PMe3 at two
different coordination positions (equatorial and apical). In addi-
tion, the in situ substitution of NH2NMe2 by (CD3)2CO as a compet-
ing ligand in high concentration readily occurs. This solution
behaviour was not observed in a CDCl3 solution of 2. Further
Table 3
Selected bond distances (Å) and angles (°) for complexes 12 and 13.
12
13
Ru1–P1
Ru1–P2
Ru1–P3
Ru1–Cl1
Ru1–N1
Ru1–N2
P1–Ru1–P2
P1–Ru1–P3
P2–Ru1–P3
P1–Ru1–Cl1
P1–Ru1–N1
P2–Ru1–N1
P3–Ru1–N1
Cl1–Ru1–N1
N2–Ru1–N1
N2–Ru1–Cl1
N2–Ru1–P3
P3–Ru1–Cl1
2.2875(5)
2.2886(6)
2.2962(6)
2.4654(6)
2.1907(2)
2.1973(2)
96.80(2)
96.25(2)
93.06(2)
170.28(2)
91.68(5)
170.40(5)
90.47(6)
82.52(5)
84.73(7)
78.92(6)
169.85(6)
91.61(2)
Ru1–P1
Ru1–P2
Ru1–P3
Ru1–P4
Ru1–Cl1
Ru1–N1
P5–F1
P1–Ru1–P2
P1–Ru1–P3
P1–Ru1–P4
P2–Ru1–P3
P2–Ru1–P4
P3–Ru1–P4
P1–Ru1–Cl1
P3–Ru1–Cl1
P4–Ru1–Cl1
N1–Ru1–Cl1
N1–Ru1–P2
2.3847(7)
2.3110(8)
2.3263(7)
2.4110(7)
2.4948(9)
2.2038(2)
1.5987(2)
90.96(3)
92.91(3)
165.086(2)
99.09(2)
91.63(3)
101.18(3)
84.41(3)
168.50(2)
80.82(3)
Fig.
4. Molecular
diagram
of
fac-[RuCl(NH3)2(PMePh2)3](PF6)Á0.5EtOH
80.18(5)
172.32(5)
(12Á0.5EtOH). Thermal ellipsoids were drawn at 50% probability level, and hydrogen
atoms (apart from the NH3 and OH functionalities) are omitted for clarity.

F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
141
Scheme 5. Stacked 1H NMR spectrum of the sequential PMe3 addition to [RuH(1,5-cod)(NH2NMe2)3](BPh4) (2).
addition to a total of 2 equivalents PMe3 reveals a triplet at
À10.98 ppm (2JHP = 55 Hz) which is ascribed to the coupling of
the hydride ligand with two different phosphorous nuclei. The con-
centration of this complex increases, where signals for the complex
[RuH(1,5-cod)(PMe)3](BPh4) appears. Addition of 4 M equivalents
of PMe3 results in direct substitution of the 1,5-cod ligand to give
[RuH(PMe3)4(L)](BPh4) (L = NH2NMe2, (CD3)2CO) and finally [RuH
(PMe3)5](BPh4). It is unclear at this stage if direct substitution of
the 1,5-cod ligand by two molecules of PMe3 is concerted at the
relative high concentrations of PMe3. The prevalence of the PMe3
ligand to coordinate over the (CD3)2CO ligand at high PMe3 concen-
trations, however, is evident.
A doublet of pentets are expected for the complex [RuH(PMe3)5]
(BPh4), but only a partially resolved doublet of pentets is observed
for the final in situ product, even after prolonged exposure to
excess PMe3. The 1H NMR spectra obtained for isolated complexes
7 and 8 in CDCl3, shows an overlapping doublet of pentets for the
hydride ligand at dH À8.78 (dp, 2JHP = 19 and 88 Hz) and À8.90 (dp,
2JHP = 19 and 89 Hz), respectively. The 31P NMR spectra of the latter
complexes corresponds to the equivalence of the phosphines
through the appearance of singlets observed at dP 20.3 (7) and
20.9 ppm (8) for the P(OMe)2Ph moieties.
tertiary phosphines and phosphonites. These complexes were
stable, isolable intermediates of the N2 and methyldiazene activa-
tion processes, which allows for further catalytic and synthetic
investigations. Intramolecular strain of the precursor complexes,
as well as the steric bulk and electronic properties of the incoming
r
-donating ligands was found to be two determining factors to the
selective formation of monohydrido-, bishydrido-, as well as
mono-ammine, and bis-ammine ruthenium(II) complexes.
Acknowledgements
This work is based on the research supported in part by the
National Research Foundation of South Africa (Grant specific
unique reference number (UID) 85386). The New Generation
Scholarship (NGS) of the University of Johannesburg (UJ) is grate-
fully acknowledged for a stipend for FPM. Single crystal X-ray
diffraction collections by Prof Petrus van Rooyen (8, 12), Dr Hong
Su (9), and Mr Leo Kirsten (10, 13) are greatly acknowledged.
Appendix A. Supplementary material
CCDC 997437, 997438, 997675, 997674 and 997676 contains
the supplementary crystallographic data for 8, 9, 10, 12 and 13,
respectively. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.
uk/data_request/cif.
These results demonstrate how the bulkier NH2NMe2 ligands is
readily substituted by smaller ligands (such as NH3), especially in
the presence of the much larger chlorido-anion as opposed to the
small hydrido-ligand. The coupling provided by the hydride and
phosphorous nuclei acted as a probe to identify at which stage
each ligand is substituted in complexes that form intermediates
which are extremely difficult to isolate or identify otherwise.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.ica.2015.08.019.
References
4. Conclusions
[1] (a) S.S. Rozenel, J. Arnold, Inorg. Chem. 51 (2012) 9730;
(b) L.D. Field, H.L. Li, S.J. Dalgarno, P. Jensen, R.D. McIntosh, Inorg. Chem. 50
(2011) 5468;
Through the synergistic effect of nitrogenase-type activity and
NH4PF6 hydrolysis, the novel ammine hydrido- and chlorido-ruthe-
nium(II) complexes [RuH(1,5-cod)(NH3)(NH2NMe2)2]X (X = PF6,
BPh4) and [RuCl(1,5-cod)(NH3)2(NH2NMe2)]X (X = PF6, BPh4) were
synthesised as products in a mixture containing the known com-
plexes [RuH(1,5-cod)(NH2NMe2)3]X (X = PF6, BPh4). All of these
complexes served as reactive precursors to a range of neutral and
cationic ruthenium(II)-ammine complexes from the reactions with
(c) L.D. Field, H.L. Li, S.J. Dalgarno, Inorg. Chem. 49 (2010) 6214;
(d) D.J. Fox, R.G. Bergman, Organometallics 23 (2004) 1656. and references
therein;
(e) G. Albertin, S. Antoniutti, L. Bonaldo, J. Castro, Polyhedron 67 (2014) 295;
(f) C.M. Kozak, P. Mountford, Angew. Chem., Int. Ed. 43 (2004) 1186.
[2] (a) G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, P.M. Dolcetti, G. Pelizzi, J.
Chem. Soc., Dalton Trans. (1997) 4435;
(b) S.O. Owalude, E.O. Odebunmi, U.B. Eke, R. Meijboom, V.N. Nesterov, E.
Singleton, N.J. Coville, Bull. Chem. Soc. Ethiop. 27 (3) (2013) 405;

142
F.P. Malan et al. / Inorganica Chimica Acta 437 (2015) 133–142
(c) N. Iizuka, S. Motoki, M. Nakai, Y. Nakabayashi, Inorg. Chem. Commun. 46
(2014) 145.
(f) T.V. Ashworth, E. Singleton, J.J. Hough, J. Chem. Soc., Dalton Trans. 1977
(1809);
[3] (a) I. Dance, Z. Anorg, Allg. Chem. 641 (1) (2015) 91;
(b) I.V. Fedoseev, N.V. Solov’ev, Russ. J. Inorg. Chem. 52 (2007) 994;
(c) N. Khoenkhoen, B. de Bruin, J.N.H. Reek, W.I. Dzik, Eur. J. Inorg. Chem.
(2015) 567.
(g) T.V. Ashworth, M.J. Nolte, E. Singleton, J. Chem. Soc. Chem. Commun. (1977)
936. and references therein.
[17] (a) T.V. Ashworth, A.A. Chalmers, E. Meintjies, H.E. Oosthuizen, E. Singleton,
Organometallics 3 (1984) 1485;
[4] (a) P.J. West, M.P. Cifuentes, T. Schwich, M.D. Randles, J.P. Morrall, E.
Kulasekera, S. Petri, R. Stranger, M.G. Humphrey, Inorg. Chem. 51 (2012)
10495;
(b) T.V. Ashworth, D.C. Liles, E. Singleton, J. Chem. Soc., Chem. Commun. (1984)
1317;
(c) D.C. Liles, H.E. Oosthuizen, A. Shaver, E. Singleton, M.B. Wiege,
Organometallics 5 (1985) 591;
(b) M. Ito, M. Hirakawa, K. Murata, T. Ikariya, Organometallics 20 (2001) 379;
(c) Y. Kayaki, H. Ikeda, J. Tsurumaki, I. Shimizu, A. Yamamoto, Bull. Chem. Soc.
Jpn. 81 (9) (2008) 1053.
(d) T.V. Ashworth, D.C. Liles, E. Singleton, Organometallics 1984 (1851) 3.
[18] (a) M.O. Albers, D.J.A. De Waal, D.C. Liles, D.J. Robinson, E. Singleton, J.
Organomet. Chem. 326 (1987) C29;
[5] (a) B.M. Barney, H.-I. Lee, P.C. Dos Santos, B.M. Hoffman, D.R. Dean, L.C.
Seefeldt, Dalton Trans. (2006) 2277;
(b) M.O. Albers, D.J.A. De Waal, D.C. Liles, D.J. Robinson, E. Singleton, M.B.
Wiege, J. Chem. Soc., Chem. Commun. (1986) 1680;
(c) M.O. Albers, D.J. Robinson, A. Shaver, E. Singleton, Organometallics 5 (1986)
2199;
(d) M.O. Albers, S.F.A. Crosby, D.C. Liles, D.J. Robinson, A. Shaver, E. Singleton,
Organometallics 1987 (2014) 6.
(b) B.A. MacKay, M.D. Fryzuk, Chem. Rev. 104 (2004) 385;
(c) U.K. Das, M. Bhattacharjee, J. Organomet. Chem. 700 (2012) 78.
[6] (a) G. Albertin, S. Antoniutti, J. Castro, J. Organomet. Chem. 697 (2012) 6;
(b) D. Sellman, A. Hille, A. Rösler, F.W. Heinemann, M. Moll, Inorg. Chim. Acta
357 (2004) 3336;
(c) D. Sellman, A. Hille, F.W. Heineman, M. Moll, A. Rösler, J. Sutter, G. Brehm,
M. Reiher, B.A. Hess, S. Schneider, Inorg. Chim. Acta 348 (2003) 194.
[7] (a) D. Sellman, A. Fürsattel, Angew. Chem., Int. Ed. 38 (1999) 2023;
(b) D. Sellman, R. Prakash, F.W. Heinemann, Eur. J. Inorg. Chem. (2004) 4291.
[8] Q.-F. Zhang, H. Zheng, W.-Y. Wong, W.-T. Wong, W.-H. Leung, Inorg. Chem. 39
(2000) 5255.
[19] M. Schlaf, A.J. Lough, R.H. Morris, Organometallics 16 (1997) 1253.
[20] D.S. Perekalin, E.E. Karslyan, A.O. Borissova, A.R. Kudinov, Mendeleev Commun.
21 (2011) 82.
[21] A. Ali, F.P. Malan, E. Singleton, R. Mejboom, Organometallics 33 (2014) 5983.
[22] Y. Nakabayashi, H. Nakamura, Y. Kubota, M. Morimoto, T. Kawasaki, M. Nakai,
O. Yamauchi, Inorg. Chim. Acta 423 (2014) 109.
[9] B.M. Barney, M. Laryukhin, R.Y. Igarashi, H.-I. Lee, P.C. Dos Santos, T.-C. Yang, B.
M. Hoffman, D.R. Dean, L.C. Seefeldt, Biochemistry 44 (22) (2005) 8030.
[10] S.L. Dabb, B.A. Messerle, G. Otting, J. Wagler, A. Willis, Chem. Eur. J. 14 (2008)
10058.
[11] L.D. Field, H.L. Li, A.M. Magill, Inorg. Chem. 48 (2009) 5.
[12] (a) J.L. Crossland, D.R. Tyler, Coord. Chem. Rev. 2010 (1883) 254;
(b) G. Albertin, S. Antoniutti, E. Bordignon, F. Chimisso, Inorg. Chem. Commun.
4 (2001) 402.
[23] D.A. Hall, G.J. Leigh, J. Chem. Soc., Dalton Trans. (1996) 3539.
[24] (a) G. Papp, H. Horváth, G. Laurenczy, I. Szatmári, Á. Kathó, F. Joó, J. Chem. Soc.,
Dalton Trans. 42 (2013) 521;
(b) J.D. Gilbertson, N.K. Szymczak, D.R. Tyler, J. Am. Chem. Soc. 127 (2005)
10184. and references therein.
[25] (a) D. Sellman, A. Hille, A. Rösler, F.W. Heinemann, M. Moll, G. Brehm, S.
Schneider, M. Reiher, B.A. Hess, W. Bauer, Chem. Eur. J. 10 (2004) 819;
(b) A.-Q. Jia, Q. Ma, H.-T. Shi, Q. Chen, W.-H. Leung, Q.-F. Zhang, Inorg. Chim.
Acta 392 (2012) 99.
[26] M.O. Albers, T.V. Ashworth, H.E. Oosthuizen, E. Singleton, Inorg. Synth. 26
(1989) 68.
[27] G.M. Sheldrick, SHELXL96, Program for the Refinement of Crystal Structures,
University of Göttingen, Germany, 1996.
[28] G.M. Sheldrick, Acta Cryst. A64 (2008) 112.
[29] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl.
Cryst. 42 (2009) 339.
[13] (a) B.A. MacKay, R.F. Munha, M.D. Fryzuk, J. Am. Chem. Soc. 128 (29) (2006)
9472;
(b) J.L. Crossland, L.N. Zakharov, D.R. Tyler, Inorg. Chem. 46 (2007) 10476;
(c) B.M. Barney, T.-C. Yang, R.Y. Igarashi, P.C. Dos Santos, M. Larykhin, H.-I. Lee,
B.M. Hoffman, D.R. Dean, L.C. Seefeldt, J. Am. Chem. Soc. 127 (2005) 14960.
[14] (a) D. Touchard, L. Morice, V. Cadierno, P. Haquette, L. Toupet, P.H. Dixneuf, J.
Chem. Soc., Chem. Commun. (1994) 859;
(b) D. Touchard, P. Haquette, S. Guesmi, L. Le Pichon, A. Daridor, L. Toupet, P.H.
Dixneuf, Organometallics 16 (1997) 3640.
[15] G. Albertin, S. Antoniutti, A. Bacchi, F. De Marchi, G. Pelizzi, Inorg. Chem. 44
(2005) 8947.
[30] S. Kuwata, Y. Mizobe, M. Hidai, Inorg. Chem. 33 (1994) 3619.
[31] A.D. Burrows, D.M.P. Mingos, S.E. Lawrence, A.J.P. White, D.J. Williams, J. Chem.
Soc., Dalton Trans. (1997) 1295.
[16] (a) T.V. Ashworth, E. Singleton, M. Laing, L. Pope, J. Chem. Soc., Dalton Trans.
1032 (1978);
[32] (a) S.P. Nolan, T.R. Belderrain, R.H. Grubbs, Organometallics 16 (1997) 5569;
(b) R.A. Jones, G. Wilkinson, I.J. Colquohoun, W. McFarlane, A.M.R. Galas, M.B.
Hursthouse, J. Chem. Soc., Dalton Trans. (1980) 2480;
(c) J. Shen, E.D. Stevens, S.P. Nolan, Organometallics 17 (1998) 3875.
[33] (a) N.A. Jasim, R.N. Perutz, S.J. Archibald, J. Chem. Soc., Dalton Trans. (2003)
2184;
(b) T.V. Ashworth, M.J. Nolte, E. Singleton, J. Chem. Soc., Dalton Trans. (1976)
2184;
(c) T.V. Ashworth, E. Singleton, M. Laing, J. Chem. Soc., Chem. Commun. (1976)
875;
(d) T.V. Ashworth, M.J. Nolte, E. Singleton, J. Chem. Soc., Dalton Trans. 1977
(1816);
(e) T.V. Ashworth, M.J. Nolte, R.H. Reimann, E. Singleton, J. Chem. Soc., Chem.
Commun. (1977) 937;
(b) K. Mashima, N. Komura, T. Yamagata, K. Tani, Inorg. Chem. 36 (1997) 2908;
(c) K.S. Coleman, J.H. Holloway, E.G. Hope, J. Langer, J. Chem. Soc., Dalton Trans.
(1997) 4555.