Silatranyl, hydride complexes of osmium(II) and osmium(IV): Crystal structure of Os(Si{OCH2CH2}3N)H3(PPh 3)3

Article abstract of DOI:10.1016/S0022-328X(00)00110-8

Reaction between Os(CO)₂(PPh₃)₃ and the silatrane, HSi{OCH₂CH₂}₃N, gives the osmium(II) silatranyl, hydride complex Os(Si{OCH₂CH₂}₃N)H(CO)₂(PPh ₃)₂ (1), as a mixture of three isomers, the structures of which were determined by NMR spectroscopy. Reaction between OsH₄(PPh₃)₃ and the silatrane, HSi{OCH₂CH₂}₃N, gives the osmium(IV) silatranyl, trihydride complex Os(Si{OCH₂CH₂}₃N)H₃(PPh ₃)₃ (2). The crystal structure of 2 has been determined and all three hydride ligands located. The three hydrides all make close approaches to the silicon atom but the distances between silicon and each of the hydrides suggests that any Si?H interactions must be weak. The interatomic distance between Si and N in the silatranyl ligand is large and the nitrogen atom has near planar geometry. Compound 2 can be methylated or protonated at nitrogen giving the complexes [Os(Si{OCH₂CH₂}₃NMe)H₃(PPh ₃)₃]I (3), and [Os(Si{OCH₂CH₂}₃NH)H₃(PPh ₃)₃]CF₃SO₃ (4), respectively.

Full text of DOI:10.1016/S0022-328X(00)00110-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 609 (2000) 177–183
Silatranyl, hydride complexes of osmium(II) and osmium(IV):
crystal structure of Os(Si{OCH2CH2}3N)H3(PPh3)3
Clifton E.F. Rickard, Warren R. Roper *, Scott D. Woodgate, L. James Wright
Department of Chemistry, The Uni6ersity of Auckland, Pri6ate Bag 92019, Auckland, New Zealand
Received 6 January 2000; received in revised form 4 February 2000
Abstract
Reaction between Os(CO)2(PPh3)3 and the silatrane, HSi{OCH2CH2}3N, gives the osmium(II) silatranyl, hydride complex
Os(Si{OCH2CH2}3N)H(CO)2(PPh3)2 (1), as a mixture of three isomers, the structures of which were determined by NMR
spectroscopy. Reaction between OsH4(PPh3)3 and the silatrane, HSi{OCH2CH2}3N, gives the osmium(IV) silatranyl, trihydride
complex Os(Si{OCH2CH2}3N)H3(PPh3)3 (2). The crystal structure of 2 has been determined and all three hydride ligands located.
The three hydrides all make close approaches to the silicon atom but the distances between silicon and each of the hydrides
suggests that any Si···H interactions must be weak. The interatomic distance between Si and N in the silatranyl ligand is large and
the nitrogen atom has near planar geometry. Compound 2 can be methylated or protonated at nitrogen giving the complexes
[Os(Si{OCH2CH2}3NMe)H3(PPh3)3]I (3), and [Os(Si{OCH2CH2}3NH)H3(PPh3)3]CF3SO3 (4), respectively. © 2000 Elsevier Sci-
ence S.A. All rights reserved.
Keywords: Hydride complexes; Silatranyl complexes; Osmium
nised. Indeed the first reported protonation and methy-
lation of this nitrogen arose from our studies of the
1. Introduction
coordinatively
unsaturated
silatranyl
complex,
Silatranes are cyclic silicon ethers of tris(2-
oxyalkyl)amine with general formula X–Si{OCH2-
CH2}3N. They are interesting examples of hypervalent
silicon compounds and have been intensively studied
since their discovery in 1961 [1]. Points of interest
related to the silatranes include the nature of any N–Si
bond, the variation in the transannular N–Si distance
and the dependence of this on the axial silicon sub-
stituent X, biological activity, reactivity, and even their
architectural beauty [2]. Theoretical studies of the na-
ture of the N–Si bond in silatranes suggest that it is
best described in terms of a dative N“Si bond with
some small contribution from a three-centre, four-elec-
tron interaction [3]. The calculated potential curve for
deformation of the N–Si distance has been found to be
very shallow [3c].
Os(Si{OCH2CH2}3N)Cl(CO)(PPh3)2, where the axial
silicon substituent is a transition metal ligand fragment
[4]. Here, the ready quaternisation can be understood
because structure determination of Os(Si{OCH2CH2}3-
N)Cl(CO)(PPh3)2 revealed a greatly expanded silatrane
cage with the nitrogen in a near planar environment. In
an extension of this work we now describe the synthesis
of coordinatively saturated silatranyl, hydride com-
plexes of osmium(II) and osmium(IV), the crystal
structure of Os(Si{OCH2CH2}3N)H3(PPh3)3, and
quaternisation reactions of this complex.
2. Results and discussion
A feature of the chemical reactivity of silatranes is
the reluctance of the bridgehead nitrogen to be quater-
2.1. Oxidati6e addition of silatrane to Os(CO)2(PPh3)3
In previous studies we have shown that oxidative
addition of the silanes, HSiR3 (R=SiMe3, SiEt3, SiPh3,
and SiPh2H), to Os(CO)2(PPh3)3 gives the correspond-
* Corresponding author. Tel.: +64-9-3737999, ext. 8320; fax: +
64-9-3737422.
E-mail address: w.roper@auckland.ac.nz (W.R. Roper).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00110-8

178
C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
isomers, A, B, and C are present in an approximate
ratio of 5:5:1.
ing osmium(II) silyl, hydride complexes Os(SiR3)H-
(CO)2(PPh3)2 [5]. As an extension of this work we now
report the oxidative addition of HSi{OCH2CH2}3N to
Os(CO)2(PPh3)3 which leads to the expected addition
product as a mixture of three geometrical isomers.
Photolysis (with a tungsten/halogen lamp), of a mix-
ture of Os(CO)2(PPh3)3 and silatrane in benzene, causes
the initially yellow solution to become colourless over a
period of 20 min. The colourless product isolated has
an elemental analysis and a FAB+ mass spectrum
consistent with the formulation Os(Si{OCH2CH2}3N)-
H(CO)2(PPh3)2 (see Scheme 1). However, the spectral
data clearly reveal that this compound is a mixture of
isomers and these isomers could not be separated. In
the IR spectrum, there are five absorptions in the
region associated with w(CO) and w(OsH), at 1902,
1942, 1976, 2015 and 2092 cm−1. All six possible
isomers for compound 1 are illustrated in Fig. 1, how-
ever, the NMR spectral data indicate that the three
The 1H-NMR spectrum of the mixture of isomers
reveals three hydride signals at high-field. The triplet
hydride resonance appearing at −7.63 ppm (2JHP
=
17.6 Hz) is assigned to isomer A. An unresolved over-
lapping doublet of doublets (an apparent triplet) at
−7.12 (‘2JHP’=20.4 Hz) is assigned to isomer B. These
two signals are in a ratio of ca. 1:1. A third signal, in
this case a well-resolved doublet of doublets, at −9.64
3
ppm (2JHPtrans=37.2 Hz, JHPcis=20.8 Hz) is attributed
to isomer C. This signal is smaller than the other two
and the ratio of A:B:C is ca. 5:5:1.
All remaining NMR data are consistent with the
three isomers in the mixture being A, B, and C. In the
31P-NMR spectrum the singlet at 9.95 ppm is assigned
to isomer A which has two-equivalent, mutually trans
triphenylphosphine ligands. The two other isomers
which could give rise to a singlet in the 31P-NMR
1
spectrum (and a triplet in the H-NMR spectrum) are
D and F, but these isomers are excluded by the 13C-
NMR data discussed below. Doublet signals at 3.81
ppm (2JPP=25.3 Hz) and 8.98 ppm (2JPP=25.1 Hz),
are assigned to isomer B which has two inequivalent cis
triphenylphosphine ligands. Isomer E would also be
compatible with this assignment but is incompatible
1
with the H- and 13C-NMR data discussed below. A
third smaller set of two doublet resonances at 3.68 ppm
(2JPP=14.7 Hz) and 4.11 ppm (2JPP=14.7 Hz) is as-
signed to isomer C. In the 13C-NMR spectrum the
signals for the silatrane cage methylene carbons of the
three isomers appear at 52.49, 52.71, and 52.84 ppm
and at 61.11, 61.09, and 60.13 ppm. The carbonyl
region also reveals the existence of three isomers. The
two triplet resonances, one at 189.35 ppm (t, CO,
2
2JCP=8.6 Hz) and a second at 186.57 (t, CO, JCP
=
10.6 Hz), are assigned to the two inequivalent carbonyls
of isomer A. Likewise, the two doublet of doublet
2
resonances at 182.95 (dd, CO, JCPtrans=74.5 Hz,
2
2JCPcis=6.0 Hz), and 187.68 (dd, CO, JCPcis=8.6 Hz,
2JCPcis=4.5 Hz) are assigned to the two inequivalent
carbonyls of isomer B, the first resonance being for the
Scheme 1. Synthesis of Os(Si{OCH2CH2}3N)H(CO)2(PPh3)2 (1) as
three isomers.
carbonyl trans to triphenylphosphine. A much weaker
2
and poorly resolved signal at 188.68 (dd, CO, JCPcis
=
2
10.0 Hz, JCPcis=6.0 Hz) is assigned to isomer C. A
29Si-NMR spectrum of the mixture of isomers was
obtained although the signal-to-noise ratio was very
low. A triplet signal at −39.10 (2JSiP=10.8 Hz) is
assigned to isomer A but the high level of background
noise in this spectrum makes it impossible to assign
further peaks.
It is noteworthy that in each of the observed isomers
A, B, and C the hyride and silatranyl ligands are cis to
one another as would be expected on both kinetic and
thermodynamic grounds. Steric effects are also appar-
ent in that in each of the three isomers A, B, and C, the
Fig. 1. Possible isomers for Os(Si{OCH2CH2}3N)H(CO)2(PPh3)2 (1).

C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
179
pared here, provides the opportunity to obtain further
information about the structure and bonding interac-
tions in compounds of the class Os(SiR3)H3L3.
Attachment of the silatranyl ligand to osmium(II) in
either a coordinatively unsaturated [4] or saturated [9]
complex results in a cage geometry with an unusually
long Si to N distance. It was also of interest, therefore,
to determine whether the silatranyl cage in an os-
mium(IV) complex would have a similarly expanded
cage geometry.
The reaction between OsH4(PPh3)3 and HSi{OCH2-
CH2}3N gave the expected silatranyl, trihydride com-
plex, Os(Si{OCH2CH2}3N)H3(PPh3)3 (2) (see Scheme
2). The infrared (IR) spectrum of 2 in the solid state,
shows three bands in the Os–H stretching region, at
2105, 2059, and 2033 cm−1. In dichloromethane solu-
tion only one broad band at 2053 cm−1 is observed.
Elemental analysis and FAB+ mass spectroscopy are
both consistent with the formulation Os(Si{OCH2-
CH2}3N)H3(PPh3)3 (2).
Scheme 2. Synthesis and reactions of Os(Si{OCH2CH2}3N)H3(PPh3)3
(2).
The 31P{1H}-NMR spectrum of 2 shows a singlet at
7.62 ppm, suggesting that the three phosphorus nuclei
are equivalent on the NMR time scale. In the 29Si{1H}-
NMR spectrum the silicon nucleus appears as a quartet
three bulkiest ligands (the two triphenylphosphines and
the silatranyl ligand) are found in a meridional arrange-
ment. Previous products obtained from the oxidative
addition of silanes to Os(CO)2(PPh3)3 usually have the
silyl and H groups cis, the carbonyl groups cis, and the
phosphine groups trans, i.e. the geometry of isomer A
[5]. An exception is that in the addition of SiH2Ph2 to
Os(CO)2(PPh3)3 to form Os(SiPh2H)H(CO)2(PPh3)2,
two isomers were observed corresponding to isomers A
and B in Fig. 1. The NMR data for compound 1
(isomer B) and the corresponding isomer of
Os(SiPh2H)H(CO)2(PPh3)2 are closely similar.
1
at −15.22 ppm (2JSiP=16.2 Hz). The H-NMR spec-
trum shows a complex multiplet at −11.19 ppm for the
three hydride ligands, together with triplet signals for
the silatranyl methylene protons. The multiplet at
1
−11.19 ppm becomes a singlet in the H{31P}-NMR
spectrum which suggests that the three hydride ligands
are also equivalent on the NMR time scale. Variable
1
temperature H-NMR studies show that the multiplet
at −11.19 ppm broadens as the temperature is lowered
from 298 to 233 K. The spin lattice relaxation times, T1,
measured between 298 and 233 K were close to 342 ms.
The T1 value of an h2-H2 is expected to be less than 20
ms, whereas the T1 value for a classical hydride would
lie between 50 and 500 ms [10]. Clearly, the T1 values
observed for 2 are in the region expected for a classical
hydride complex. Similar observations were made for
Os(Si{Pyrrolyl}3)H3(PPh3)3 [6].
2.2. Reaction of silatrane with OsH4(PPh3)3
The osmium(IV) complex, OsH4(PPh3)3 reacts with
the silanes HSiR3 (R=Et, Ph, Pyrrolyl) to form the
corresponding metal complexes, Os(SiR3)H3(PPh3)3 [6].
The bonding situation in these complexes was explored
through X-ray crystal structure determination of the
complex, Os(SiPyrrolyl3)H3(PPh3)3 (although the hy-
dride ligands were not located), and through theoretical
calculations of the model compounds Os(SiR3)H3-
(PH3)3 (R=H, NH2, Pyrrolyl). The conclusion was
that there was a small but significant bonding interac-
tion between the silicon and all three hydride ligands,
the major source of this interaction involving overlap
between the hydrogen s orbitals and the s*(Os–Si).
Related weak Si···H interactions for situations involv-
ing one silicon, one hydrogen, and one metal centre,
have been widely documented and discussed by Schu-
bert [7] and by others [8]. For early metal complexes,
several examples where one hydride ligand and two silyl
ligands are involved, have been recognised [8]. Study of
the compound Os(Si{OCH2CH2}3N)H3(PPh3)3 pre-
2.3. Crystallographic study of
Os(Si{OCH2CH2}3N)H3(PPh3)3 (2)
The structure of 2 was obtained by an X-ray crystal
structure determination (see Table 1), and the molecu-
lar geometry is depicted in Fig. 2. The silicon and the
three phosphorus atoms are arranged in an approxi-
mately tetrahedral manner about osmium and selected
bond lengths and bond angles are presented in Table 2.
All three hydride ligands were located and refined
(Os–H(1), 1.52(3); Os–H(2), 1.66(3); Os–H(3), 1.57(3)
,
A). Each hydrogen atom is approximately trans to a
phosphorus atom. The calculated distances between Si

180
C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
Table 2
and H are Si···H(1), 2.06(4); Si···H(2), 2.00(4); Si···H(3),
,
Selected bond lengths (A) and angles (°) for 2
,
1.96(3) A. This is indicative of, at best, a very weak
interaction since Schubert has suggested that the short-
est possible non-bonding contact between Si and H
Bond lengths
Os–P1
Os–P2
Os–P3
Os–Si
2.3921(9)
2.3735(8)
2.3854(8)
2.3442(8)
Os–H1
Os–H2
Os–H3
1.52(3)
1.66(3)
1.57(3)
,
centres is 2.0 A [7,11]. There is approximately threefold
symmetry about the osmium–silicon axis. The three O
atoms bound to Si and the three H atoms bound to Os,
are in a staggered arrangement. The average P–Os–P
angle is ca. 101° and the average Si–Os–P angle is
larger at 117°. Each hydride ligand can be viewed as
Bond angles
Si–Os–P1
Si–Os–P2
Si–Os–P3
P1–Os-P2
P1–Os–P3
P2–Os–P3
P1–Os–H1
118.82(3)
110.77(3)
121.00(3)
100.59(3)
98.44(3)
P2–Os–H2
P3–Os–H3
Os–Si–O1
Os–Si–O2
Os–Si–O3
O1–Si–O2
O1–Si–O2
O2–Si–O3
167.4(12)
174.1(13)
113.42(9)
114.08(9)
113.61(10)
103.98(13)
105.46(13)
105.33(14)
Table 1
104.44(3)
176.8(13)
Crystal data and structure refinement for 2
Formula
Molecular weight
Temperature (K)
C60H60NO3OsP3Si
1154.29
203
capping one of the three SiP2 faces of the distorted
tetrahedron. It should be noted that the three hydrides
were found to be located in the positions predicted by
theoretical calculations for the closely related complex,
Os(SiPyrrolyl3)H3(PPh3)3 [6]. The Os–Si bond distance
,
Wavelength (A)
0.71073
Orthorhombic
P212121
13.8391(1)
16.8507(2)
21.9290(1)
5113.86(7)
4
1.499
2344
2.658
0.45×0.24×0.18
0.381, 0.646
3, 56
31 768
11 615, Rint=0.0207
10 871
Crystal system
Space group
,
a (A)
,
b (A)
,
c (A)
,
3
(2.3442(8) A) is slightly longer than the value of 2.2293
,
V (A )
Z
,
A observed for Os(SiPyrrolyl3)H3(PPh3)3 [6]. The inter-
Dcalc (g cm−3
F(000)
)
atomic distance between silicon and nitrogen of
,
3.242(3) A is longer even than the values observed in
v (mm−1
)
the five-coordinate osmium(II) silatranyl complexes
previously reported [4] and must represent a situation
where there is effectively no bonding interaction be-
tween Si and N. The sum of the angles around the
nitrogen atom is 357.8°, and the deviation of nitrogen
from the plane through C(2), C(4), and C(6) is 0.124(4)
Crystal size (mm)
A (min, max)
2q (min, max) (°)
Reflections collected
Independent reflections
Observed reflections
Refinement method
Full-matrix least-squares
,
A, with the nitrogen pointing away from the silicon.
on F2
Goodness-of-fit on F2
R (observed data)
R (all data)
1.042
R1=0.0236, wR2=0.0525
R1=0.0274, wR2=0.0548
+0.86, −0.66
2.4. Methylation and protonation of the silatranyl
nitrogen in Os(Si{OCH2CH2}3N)H3(PPh3)3 (2)
−3
,
Difference map (min, max) e A
In silatranes, excluding those examples where the
silatrane is bound as a silatranyl ligand, the nitrogen is
pyramidal and points inwardly towards the silicon with
an accompanying weak Si–N interaction. The structure
of compound 2 reveals an elongated cage geometry
with the nitrogen only slightly pyramidal but pointing
away from silicon. In the osmium(II) silatranyl com-
plexes previously described [4] and in the platinum(II)
silatranyl complex, Pt(Si{OCH2CH2}3N)Cl(PMe2Ph)2
[12], the silatrane cages are also expanded with the
nitrogens in near-planar arrangements. Since the osmiu-
m(II) complexes were readily quaternised at nitrogen it
was expected that compound 2 would behave similarly.
Indeed this was found to be the case and treatment
of 2 with methyl iodide gives the complex, [Os(Si-
{OCH2CH2}3NMe)H3(PPh3)3]I (3) (see Scheme 2). In
the 1H-NMR spectrum for 3 the quaternary methyl
group protons appear as a singlet resonance at 3.42
ppm, while the osmium–hydride signals appear at
Fig. 2. Molecular geometry of Os(Si{OCH2CH2}3N)H3(PPh3)3 (2).

C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
181
a position (−10.62 ppm) similar to those observed in
the starting material. The carbon resonance for the
methyl group on nitrogen is at 62.60 ppm in the
13C-NMR spectrum. The 29Si-NMR spectrum shows a
poorly resolved multiplet at −3.50 ppm, ca. 12 ppm
downfield from the Si chemical shift in the parent
complex.
ppm) or the proteo-impurity in the solvent (7.25 ppm
for CHCl3). 13C-NMR spectra were referenced to
CDCl3 (77.00 ppm), 31P-NMR spectra to 85% ortho-
phosphoric acid (0.00 ppm) as an external standard,
and 29Si-NMR spectra to tetramethylsilane (0.00 ppm).
Mass spectra were recorded using the fast atom bom-
bardment technique with a Varian VG 70-SE mass
spectrometer. Melting points (uncorrected) were deter-
mined on a Reichert hot stage microscope. Elemental
analyses were obtained from the Microanalytical Labo-
ratory, University of Otago.
Protonation of 2 with one equivalent of triflic acid
also proceeds as expected (see Scheme 2). The resulting
complex,
[Os(Si{OCH2CH2}3NH)H3(PPh3)3]CF3SO3
(4), shows a broad singlet at 10.55 ppm in the 1H-NMR
spectrum (which disappears when D2O is added) and
this is assigned to the NH. The 29Si-NMR spectrum of
4 shows a multiplet at −3.40 ppm, similar to the value
recorded for complex 3. The Os–H signals are almost
4.2. Os(Si{OCH2CH2}3N)H(CO)2(PPh3)2 (1)
Os(CO)2(PPh3)3 (200 mg, 0.194 mmol) was added to
deoxgenated benzene containing HSi{OCH2CH2}3N
(37 mg, 0.21 mmol). The bright-yellow solution was
subjected to photolysis using a 1000 W tungsten/halo-
gen lamp. After 20 min, the resulting colourless solu-
tion was reduced in volume in vacuo and ethanol (15
ml) was added. The colourless solid was removed by
filtration and recrystallised from dichloromethane/etha-
nol (25 ml:10 ml) to give 1 as a mixture of three
isomers, A, B, and C (152 mg, 83%). M.p. 220–223 °C.
m/z 948.2044: C42H42ClN2O4OsP2Si requires 948.2079.
Anal. Calc. for C42H42ClN2O4OsP2Si: C, 56.07; H, 4.47;
N, 1.42. Found: C, 56.00; H, 4.11; N, 1.63%. IR
(cm−1): 1902, 1942, 1976, 2015 (CO); 2092, 1402, 1384,
1
unchanged, appearing in the H-NMR spectrum as a
multiplet centred at −10.52 ppm.
3. Conclusion
We have shown that the silatrane, HSi{OCH2-
CH2}3N, in common with other silanes, undergoes an
oxidative addition reaction with Os(CO)2(PPh3)3. The
silatranyl, hydide product, Os(Si{OCH2CH2}3N)H-
(CO)2(PPh3)2 (1), consists of an inseparable mixture of
three isomers, the geometries of which have been deter-
mined
by
multinuclear
NMR
spectroscopy.
HSi{OCH2CH2}3N also reacts with OsH4(PPh3)3 to
give the silaranyl, trihydride, Os(Si{OCH2CH2}3N)H3-
(PPh3)3 (2), the structure of which has been determined
by X-ray crystallography, complete with the location of
the hydride ligands. The structure also reveals an ex-
panded cage geometry for the silatranyl ligand with the
nitrogen atom pointing away from silicon. This nitro-
gen atom is readily quaternised. Thus, both osmium(II)
and osmium(IV) have a similar effect upon silatranyl
ligand geometry and silatranyl nitrogen reactivity.
1
1329, 1115, 1099, 1022, 939, 916, 860, 798. H-NMR
(CDCl3; l): −9.64 ppm (dd, 0.1H, OsH (isomer C),
2
2JHPtrans=37.2 Hz, JHPcis=20.8 Hz), −7.63 (t, 0.45H,
2
OsH (isomer A), JHP=17.6 Hz) −7.12 (‘t’ [overlap-
ping dd], 0.45H, OsH (isomer B), 2JHP=20.4 Hz);
2.5–2.9 (m, CH silatranyl, all isomers) 3.1–3.5 (m, CH
silatranyl, all isomers), 7.10–7.71 (m, 30H, PPh3). 13C-
NMR (CDCl3; l): 52.49 (s, CH2N); 52.71 (s, CH2N),
52.84 (s, CH2N), 60.13 (s, OCH2), 61.09 (s, OCH2);
127.0–128.0 (m, PPh3), 128.6–129.3 (m, PPh3), 133.1–
134.2 (m, PPh3); 189.35 (t, CO isomer A, 2JCP=8.6
2
Hz), 186.57 (t, CO isomer A, JCP=10.6 Hz); 187.68
4. Experimental
2
2
(dd, CO isomer B, JCPcis=8.6 Hz, JCPcis=4.5 Hz);
2
2
182.95 (dd, CO isomer B, JCPtrans=74.5 Hz, JCPcis
=
4.1. General procedures and instruments
2
6.0 Hz); 188.68 (dd, CO isomer C, JCPcis=10.0 Hz,
2JCPcis=6.0 Hz). 29Si-NMR (CDCl3; l): −39.10 (t,
Standard laboratory procedures were followed as
have been described previously [13]. The compounds
Os(CO)2(PPh3)3 [14] and OsH4(PPh3)3 [15] were pre-
pared according to literature methods.
OsSi isomer A, JSiP=10.8 Hz). 31P-NMR (CDCl3; l):
2
2
9.95 (s, isomer A); 8.98 (d, isomer B, JPP=25.1 Hz);
2
3.81 (d, isomer B, JPP=25.3 Hz); 4.11 (d, isomer C,
2JPP=14.7 Hz); 3.68 (d, isomer C, JPP=14.7 Hz).
2
IR spectra (4000–400 cm−1) were recorded as Nujol
mulls between KBr plates on a Perkin–Elmer Paragon
1000 spectrometer. NMR spectra were obtained on a
4.3. Os(Si{OCH2CH2}3N)H3(PPh3)3 (2)
1
Bruker DRX 400 at 25 °C. H-, 13C-, 31P-, and 29Si-
NMR spectra were obtained operating at 400.1 (1H),
100.6 (13C), 162.0 (31P), and 79.5 (29Si) MHz, respec-
tively. Resonances are quoted in ppm and 1H-NMR
spectra referenced to either tetramethylsilane (0.00
OsH4(PPh3)3 (200 mg, 0.204 mmol) and
HSi{OCH2CH2}3N (72 mg, 0.41 mmol) were heated
under reflux in toluene for 3 h. The toluene was re-
moved from the black solution in vacuo and the

182
C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
product was dissolved in dichloromethane and filtered
through a Celite pad. Ethanol (20 ml) was added, and
the dichloromethane was removed on a rotary evapora-
tor. The light-grey solid was collected and recrystallised
a further time from dichloromethane:ethanol (25 ml:10
ml) to yield colourless crystals of pure 2 (148 mg, 63%).
M.p. 175–179°C. m/z 1156.3270, C60H60NO3OsP3Si re-
quires 1156.3249. Anal. Calc. for C60H60NO3OsP3Si·
1/2CH2Cl2C: 60.72; H, 5.14; N, 1.17. Found: C, 60.88;
H, 5.10; N, 1.15%. IR (cm−1): 2105, 2059, 2033
w(OsH); 1586, 1384, 1328, 1125, 1085, 1079, 906, 863,
IR (cm−1) 3433br (NH); 2025br (OsH); 1585, 1571,
1401, 1257, 1220, 1127, 1070, 1090, 912, 829, 740, 690,
634. H-NMR (CDCl3; l): −10.52 (m, 1H, OsH); 3.62
(s broad, 6H, CH2N); 3.85 (s broad, 6H, OCH2); 10.55
(s broad, 1H, NH); 6.97–7.33 (m, 30H, PPh3). 13C-
NMR (CDCl3; l): 53.55 (s, CH2N); 61.42 (s, OCH2);
127.96 (m, PPh3); 128.22 (s, PPh3); 133.97 (m, PPh3);
134.01 (m, PPh3). 29Si–NMR (CDCl3; l): −3.40 (m,
OsSi ).
1
4.6. X-ray crystal structure determination of
Os(Si{OCH2CH2}3N)H3(PPh3)3 (2)
1
660. H-NMR (CDCl3; l): −11.19 (m, 3H, OsH); 2.84
(t, 6H, CH2N, 3JHH=4.0 Hz); 3.48 (t, 6H, OCH2,
3JHH=4.0 Hz); 6.95–7.36 (m, 30H, PPh3). 13C-NMR
(CDCl3; l): 53.34 (s, CH2N); 61.55 (s, OCH2); 126.96
(m, PPh3); 128.15 (m, PPh3); 133.99 (m, PPh3); 133.99
(m, PPh3). 29Si-NMR (CDCl3; l): −15.22 (q, OsSi,
2JSiP=16.2). 31P-NMR (CDCl3; l) 7.62 (s, PPh3). De-
termination of the T1 values for the hydride resonances
of 2 were carried out by an inversion recovery NMR
experiment at 400 MHz. Values for temperature (K)
and T1 (ms) are: 298, 342.2; 278, 341.4; 233, 342.6.
A suitable crystal was grown from dichloromethane/
ethanol. Data were collected on a Siemens SMART
diffractometer with a CCD area detector and covered a
nominal hemisphere. Lorentz and polarisation correc-
tions were applied and absorption corrections using the
program SADABS [16] yielding 31 768 measured
reflections.
The structure was solved by Patterson and Fourier
techniques using SHELXS-97 [17] and refined by full-ma-
trix least-squares on F2 using SHELXL-97 [18]. All non-
hydrogen atoms were allowed to refine anisotropically.
Hydrogen atoms, other than those bonded to osmium,
were placed geometrically and refined with a riding
model with Uiso 20% greater than the carrier atom. The
hydrogen atoms bonded to osmium were located from
difference maps and their coordinates allowed to refine
with thermal parameters fixed at 20% greater than the
osmium atom. Refinement converged to conventional
R=0.0236 for the 10 871 reflections with I\2|(I).
Crystal data and refinement parameters are given in
Table 1 and selected bond lengths and angles in Table
2.
4.4. [Os(Si{OCH2CH2}3NMe)H3(PPh3)3]I (3)
Os(Si{OCH2CH2}3N)H3(PPh3)3 (200 mg, 0.173
mmol) was heated under reflux in MeI for 45 min.
Ethanol (10 ml) was added to the dark-grey solution
and the MeI removed. The resulting dark-grey product
was recrystallised from dichloromethane:ethanol (25
ml:10 ml) to give colourless crystals of pure 3 (175 mg,
78%). M.p. 176–178°C. m/z 1168.3353; C61H63NO3-
OsP3Si requires 1168.3375. Anal. Calc. for C61H63-
INO3OsP3Si.CH2Cl2: C, 53.92; H, 4.74; N, 1.01. Found:
C, 54.35; H, 4.92; N, 1.00%. IR (cm−1) 2037br (OsH);
1586, 1573, 1401, 1257, 1224, 1127, 1065, 1088, 910,
1
832, 743, 697, 636, 520. H-NMR (CDCl3; l): −10.62
(m, 3H, OsH); 3.42 (s, 3H, CH3); 3.57 (s broad, 6H,
CH2N); 3.79 (s broad, 6H, OCH2); 6.97–7.33 (m, 30H,
PPh3). 13C-NMR (CDCl3; l): 57.29 (s, CH2N); 62.60 (s,
CH3); 65.48 (s, OCH2); 127.12 (m, PPh3); 128.22 (s,
PPh3); 133.52 (m, PPh3); 134.05 (m, PPh3). 29Si-NMR
(CDCl3; l): −3.50 (m, OsSi ).
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 138312. Copies of the data can
be obtained free of charge from The Director, CCDC,
12 Union Rd., Cambridge CB2 1EX, UK (Fax: +44-
1223-336033; e-mail: deposit@ccdc.com.ac.uk or www:
http://www.ccdc.cam.ac.uk).
4.5. [Os(Si{OCH2CH2}3NH)H3(PPh3)3]CF3SO3 (4)
Triflic acid (18 ml, 0.17 mmol) and ethanol (1 ml)
were added to a dichloromethane (25 ml) solution
containing Os(Si{OCH2CH2}3N)H3(PPh3)3 (200 mg,
0.173 mmol). The resulting grey solution was stirred for
30 min, further ethanol (10 ml) was added, and the
dichloromethane was removed. The resulting product
was recrystallised from dichloromethane:ethanol (25
ml:10 ml) to give pure 4 as colourless crystals (194 mg,
86%). Anal. Calc. for C61H61F3NO6OsP3SSi: C, 56.17;
H, 4.71; N, 1.07. Found: C, 56.56; H, 4.99; N, 1.25%.
Acknowledgements
We thank the University of Auckland Research
Committee for partial support of this work through
Grants-in-Aid and through the award of a Doctoral
Scholarship to SDW.

C.E.F. Rickard et al. / Journal of Organometallic Chemistry 609 (2000) 177–183
183
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