Preparation of hydroxylamine complexes of ruthenium(II), osmium(II) and iridium(III)

Article abstract of DOI:10.1002/ejic.200300065

The hydroxylamine complexes [MH(NH₂OH)P₄]BPh ₄ (M = Ru, Os) and [Ru(NH₂OH)₂P ₄](BPh₄)₂ [P = P(OEt)₃, PPh(OEt)₂] were prepared by allowing the triflate species MH(K ¹-OSO₂CF₃)P₄ and [Ru(κ ²-O₂SOCF₃)P₄]⁺ to react with an excess of hydroxylamine. The iridium complexes [IrCl₂(NH ₂OH)PL₂]BPh₄ [P = P(OEt)₃, PPh(OEt)₂; L = PPh₃, AsPh₃] and [IrH ₂(NH₂OH)(PPh₃)₃]BPh₄ were also prepared by reacting the hydride species [IrHCl₂PL ₃] and [IrH₃(PPh₃)₃] first with triflic acid and then with an excess of NH₂OH. The O-iminoacylated hydroxylamine complexes [M{η²-NH=C(R)ONH₂}P ₄](BPh₄)₂ and [M{η ²-NH=C(R)ONH-(CH₃)}P₄](BPh₄) ₂ (M = Ru, Os; R = CH₃, 4-CH₃C ₆H₄) were prepared by allowing the nitrile complexes [M(RCN)₂P₄](BPh₄)₂ to react with hydroxylamine (NH₂OH) or N-methylhydroxylamine [NH(CH ₃)OH]. The compounds were characterised spectroscopically (IR, ¹H, ¹³C and ³¹P NMR) and a geometry in solution was also established. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200300065

FULL PAPER
Preparation of Hydroxylamine Complexes of Ruthenium(II), Osmium(II) and
Iridium(III
)
Gabriele Albertin,*[a] Stefano Antoniutti,[a] Samuele Beraldo,[a] and Fabio Chimisso[a]
Keywords: Hydroxylamines / N ligands / P ligands / Ruthenium / Osmium / Iridium
The hydroxylamine complexes [MH(NH2OH)P4]BPh4 (M =
Ru, Os) and [Ru(NH2OH)2P4](BPh4)2 [P = P(OEt)3, PPh(OEt)2]
were prepared by allowing the triflate species MH(κ1-
[M{η2-NH=C(R)ONH2}P4](BPh4)2 and [M{η2-NH=C(R)ONH-
(CH3)}P4](BPh4)2 (M = Ru, Os; R = CH3, 4-CH3C6H4) were
prepared
by
allowing
the
nitrile
complexes
OSO2CF3)P4 and [Ru(κ2-O2SOCF3)P4]+ to react with an ex- [M(RCN)2P4](BPh4)2 to react with hydroxylamine (NH2OH)
cess
of
hydroxylamine.
The
iridium
complexes
or N-methylhydroxylamine [NH(CH3)OH]. The compounds
were characterised spectroscopically (IR, 1H, 13C and 31P
NMR) and a geometry in solution was also established.
[IrCl2(NH2OH)PL2]BPh4 [P = P(OEt)3, PPh(OEt)2; L = PPh3,
AsPh3] and [IrH2(NH2OH)(PPh3)3]BPh4 were also prepared
by reacting the hydride species [IrHCl2PL3] and
[IrH3(PPh3)3] first with triflic acid and then with an excess
of NH2OH. The O-iminoacylated hydroxylamine complexes
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Results and Discussion
Introduction
Preparation of Hydroxylamine Complexes
Hydroxylamine is a bifunctional molecule of simple con-
stitution and structure, which has a somewhat unexplored
coordination chemistry. Apart from the proposed
[IrCl3(NH2OH)(PPh3)2] compound,[1] obtained by pro-
tonation of [Ir(NO)(PPh3)3] with HCl, and the
[Fe(TPP)(NH2OH)2] derivative (TPP ϭ tetraphenylporphy-
rinate),[2] prepared by reacting Fe(TPP) with NH2OH at
low temperature, only recently[3] have some examples
Mono- and bis(hydroxylamine) complexes of ruthenium
and
osmium
[MH(NH2OH)P4]BPh4
(1Ϫ3)
and
[M(NH2OH)2P4](BPh4)2 (4) [P ϭ P(OEt)3, PPh(OEt)2],
were prepared by substituting the triflato ligand in the
corresponding precursors, as shown in Scheme 1.
of
hydroxylamine
complexes
of
the
type
[MX(NH2OH)(CO)2(PPh3)2]CF3SO3 (M ϭ Ru, Os; X ϭ
Cl, Br) and [Re(NH2OH)(CO)3(PPh3)2]CF3SO3 been re-
ported. In contrast with numerous studies on hydrazine de-
rivatives,[4,5] no further studies have been reported on the
chemistry of hydroxylamine complexes, although NH2OH
is isoelectronic and somewhat similar to NH2NH2.
We have previously reported[6] the synthesis and the reac-
tivity of mono- and bis(hydrazine) complexes of transition
metals such as Mn, Fe, Ru, Os and Ir and have now ex-
tended these studies to hydroxylamine and methylhy-
droxylamine with the aim of testing the behaviour of these
molecules as a ligand on appropriate metal fragments and,
if possible, of carrying out a comparison with related hydra-
zine complexes. The results of these studies, which also in-
clude hydroxylamine reactions with coordinated nitriles,[7]
are reported here.
Scheme 1
The triflate precursors [MH(κ1-OSO2CF3)P4] and [M(κ2-
O2SOCF3)P4]ϩ were generated in situ, in the case of ru-
thenium,[6a] by reacting the hydride complexes [MH2P4]
with an equimolar or an excess amount of triflic acid, while
[a]
`
Dipartimento di Chimica dellЈUniversita CaЈ Foscari di
Venezia,
Dorsoduro 2137, 30123 Venezia, Italy
Eur. J. Inorg. Chem. 2003, 2845Ϫ2854
DOI: 10.1002/ejic.200300065
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2845

G. Albertin, S. Antoniutti, S. Beraldo, F. Chimisso
FULL PAPER
with osmium[6c] the reaction first with methyl triflate and ine complexes,[3] an N-bonded NH2OH ligand. Therefore,
then with CF3SO3H was used (Scheme 2).
in the absence of an X-ray structure determination, the N-
coordination (Scheme 1) should be considered more likely
in this case.
In the temperature range between ϩ30 and Ϫ80 °C the
31P{1H} NMR spectra of mono-hydroxylamine complexes
1Ϫ3 appear as AB2C multiplets, which can be simulated
using the parameters reported in Table 1, suggesting a mut-
ual cis arrangement (I) of the hydride and NH2OH ligands
(Scheme 1). An A2B2 multiplet, instead, is present in the
spectra of the bis(hydroxylamine) complex 4, in agreement
with a mutually cis position (II) of the two NH2OH ligands.
These studies on the synthesis of NH2OH complexes
have been extended to other metals with a d6 configuration.
We found that, in the case of iridium, the use of appropriate
Scheme 2. P ϭ P(OEt)3, PPh(OEt)2
Substitution of the triflato ligand was easy for ru- precursors containing mixed phosphite-phosphane (or ar-
thenium, allowing the preparation of both mono- (1, 2) and sane) ligands allows the synthesis of stable hydroxylamine
bis(hydroxylamine) (4) complexes. In the case of osmium, derivatives. Treatment of [IrHCl2PL2], first with triflic acid
however, only the mono-substituted derivative 3 was ob- and then with an excess of NH2OH, gives the hydroxylam-
tained in pure form. Attempts to prepare the bis-species, in ine complexes [IrCl2(NH2OH)PL2]ϩ (5Ϫ8) [P ϭ P(OEt)3,
fact, gave white solids, which probably contain (by NMR) PPh(PEt)2; L ϭ PPh3, A5Ph3], which were isolated as their
a
mixture of [Os(NH2OH)2P4]2ϩ
,
[Os(κ1-OSO2CF3)- BPh4 salts and characterised (Scheme 3).
(NH2OH)P4]ϩ and decomposition products whose separ-
ation was unsuccessful.
The hydroxylamine complexes 1Ϫ4 are white or pale-yel-
low solids that are stable in air and in solution in polar
organic solvents, where they behave as 1:1 (1Ϫ3) or as 1:2
(4) electrolytes.[8] Analytical and spectroscopic data
(Table 1) support the proposed formulations. Both the IR
and 1H NMR spectroscopic data are diagnostic for the
presence of the NH2OH ligand. The IR spectra, in fact, Scheme 3. L ϭ PPh3, P ϭ P(OEt)3 5, P ϭ PPh(OEt)2 6; L ϭ AsPh3,
P ϭ P(OEt)3 7, P ϭ PPh(OEt)2 8
show a slightly broad medium-intensity band at 3487Ϫ3318
cmϪ1, attributed to ν(OH), and two ν(NH) absorptions at
Protonation of [IrHCl2PL2] with CF3SO3H leads[6d] to
3326Ϫ3223 cmϪ1 of the hydroxylamine ligand. In the spec-
the evolution of H2 and probable formation of either the
tra of the mono-substituted derivatives 1Ϫ3 one weak band
triflate [Ir(κ1-OSO2CF3)Cl2PL2] or the pentacoordinate cat-
is also present at 1955Ϫ1820 cmϪ1, due to the ν(MH) ab-
ions [IrCl2PL2]ϩ, which, when treated with an excess of hy-
sorption of the hydride ligand. Its presence is confirmed by
droxylamine, give the final complexes 5Ϫ8.
1
the H NMR spectra, which show the characteristic high-
The IrCl2PL2 fragment seems to be peculiar to the forma-
field multiplet due to the coupling with the phosphorus nu-
tion of stable hydroxylamine complexes, since the use of
clei, simulated using an AB2CX model (X ϭ H) with the
other precursors such as [IrHCl2(PPh3)3], [IrHCl2(AsPh3)3]
parameters reported in Table 1.
or [IrH2Cl(PPh3)3] does not allow the preparation of
Further support for the presence of the NH2OH ligand
NH2OH derivatives. The only other fragment we found to
1
comes from the H NMR spectra, which show, for com-
be able to bind NH2OH is [IrH2(PPh3)3], which gives the
pounds 1 and 2, a slightly broad multiplet at δ ϭ
stable and isolable complex [IrH2(NH2OH)(PPh3)2]BPh4
6.13Ϫ6.02 ppm, attributed to the NH2 protons, and a broad
(9). In fact, treatment of the trihydride [IrH3(PPh3)3], first
signal at δ ϭ 4.98Ϫ4.44 ppm, attributed to the OH hydro-
with an equimolar amount of triflic acid and then with an
gen atom of the hydroxylamine ligand. These assignments
excess of NH2OH, produces the hydroxylamine complex 9,
are confirmed by integration and 1H COSY experiments. In
which was isolated and characterised (Scheme 4).
the spectra of compounds 3 and 4, on the other hand, only
the NH2 proton signal at δ ϭ 6.61Ϫ5.80 ppm is unambigu-
ously attributable, while the OH signal is masked by the
signals of the CH2 protons. The low-frequency values ob-
served for our proton OH signals as compared with those
(δ ϭ 8Ϫ9 ppm) of known hydroxylamine derivatives[1,3]
may suggest an O-coordination of the NH2OH ligand.
However, the 1H NMR spectra show a small coupling
(3JP,H ഠ 1 Hz) of the NH2 protons with the phosphorus
nuclei which seems to support, like the known hydroxylam- Scheme 4
2846
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Eur. J. Inorg. Chem. 2003, 2845Ϫ2854

Hydroxylamine Complexes of RuII, OsII and IrIII
FULL PAPER
Table 1. IR and NMR spectroscopic data for hydroxylamine complexes
Complex
IR
1H NMR[b][c]
δ (J/Hz)
Spin
system
31P{1H}NMR[b] [d]
δ (J/Hz)
cmϪ1
Assignment
Assignment
[RuH(NH2OH){P(OEt)3}4]BPh4 (1)
3487 m
3326 m
3259 m
1820 m
ν(OH)
ν(NH)
6.13 m, br
4.44 br
NH2
OH
AB2C
δA ϭ 147.5
δB ϭ 141.1
δC ϭ 136.7
JAB ϭ 63.0
JAC ϭ 42.2
JBC ϭ 45.0
4.24Ϫ3.88 m
1.36 t
CH2
CH3
ν(RuH)
1.32 t
1.27 t
Ϫ7.71 to Ϫ8.68 m
RuH
NH2
OH
[e]
6.27 m, br
5.26 m
4.19 m
CH2
3.95 qnt
1.33 t
CH3
1.30 t
1.26 t
AB2CX
δX Ϫ8.19
JAX ϭ 24.2
JBX ϭ 24.5
JCX ϭ 122.1
RuH
[RuH(NH2OH){PPh(OEt)2}4]BPh4 (2)
3407 m
3299 m
3223 w
1946 m
ν(OH)
ν(NH)
6.02 m, br
4.98 br
NH2
OH
AB2C
δA ϭ 169.7
δB ϭ 164.1
δC ϭ 159.4
JAB ϭ 46.9
JAC ϭ 29.7
JBC ϭ 31.4
4.00Ϫ3.15 m
1.28 t
CH2
CH3
ν(RuH)
1.23 t
1.19 t
0.92 t
AB2CX
RuH
δX Ϫ8.02
JAX ϭ 24.5
JBX ϭ 24.0
JCX ϭ 105.2
[OsH(NH2OH){P(OEt)3}4]BPh4 (3)
3481 m, br
3321 m
ν(OH)
ν(NH)
6.61 br
NH2
CH2
CH3
AB2C
δA ϭ 102.4
δB ϭ 102.0
δC ϭ 96.3
JAB ϭ 34.3
JAC ϭ 26.9
JBC ϭ 43.7
4.22Ϫ3.84 m
1.36 t
3265 w
1955 w
ν(OsH)
1.31 t
1.28 t
AB2CX
OsH
δX Ϫ9.14
JAX ϭ 45.8
JBX ϭ 21.6
JCX ϭ Ϫ107.9
[Ru(NH2OH)2{P(OEt)3}4](BPh4)2 (4)
3318 m
ν(OH)
ν(NH)
5.80 m, br
4.05 m
1.35 t
NH2
CH2
CH3
A2B2
AB2
AB2
δA ϭ 129.6
δB ϭ 119.8
JAB ϭ 60.3
3290 m, br
1.29 t
[IrCl2(NH2OH){P(OEt)3}(PPh3)2]BPh4 (5)
[IrCl2(NH2OH){PPh(OEt)2}(PPh3)2]BPh4 (6)
3258 m
3215 m
1601 m
ν(NH)
5.45 m, br
3.42 qnt
1.00 t
NH2
CH2
CH3
δA ϭ 32.1
δB ϭ Ϫ19.2
JAB ϭ 27.5
δNH2
νIrCl
[f]
393 m
3490 m
3258 m
3215 m
1616 m
ν(OH)
ν(NH)
5.62 m
3.50 m
1.08 t
NH2
CH2
CH3
δA ϭ 64.3
δB ϭ Ϫ22.5
JAB ϭ 21.0
δ(NH2)
[IrCl2(NH2OH){P(OEt)3}(AsPh3)2]BPh4 (7)
[IrCl2(NH2OH){PPh(OEt)2}(AsPh3)2]BPh4 (8)
3254 m
3213 m
1624 m
ν(NH)
5.73 br
3.55 qnt
1.00 t
NH2
CH2
CH3
A
A
32.84 s
64.3 s
δ(NH2)
3256 m
3213 m
1616 m
ν(NH)
5.83 m
3.52 qnt
1.05 t
NH2
CH2
CH3
δ(NH2)
ν(IrCl)
[f]
386 m
[IrH2(NH2OH)(PPh3)3]BPh4 (9)
3275 m
3219 m
2179 w
2130 w
1614 m
ν(NH)
νIrH)
5.26 br
NH2
OH
IrH
A2B
δA ϭ 9.81
δB ϭ 5.46
JAB ϭ 12.8
3.39 br
A2BXY
δX Ϫ12.19
δY Ϫ20.68
JAX ϭ 21.3
JAY ϭ 16.8
JBX ϭ 120
JBY ϭ 12.5
JXY ϭ 46.3
δ(NH2)
Eur. J. Inorg. Chem. 2003, 2845Ϫ2854
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 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2847

G. Albertin, S. Antoniutti, S. Beraldo, F. Chimisso
FULL PAPER
Table 1. (Continued)
Complex
IR[a]
cmϪ1
1H NMR[b][c]
Assignment δ (J/Hz)
Spin
31P{1H}NMR[b] [d]
δ (J/Hz)
Assignment system
[Ru(η2-NHϭC(CH3)ONH2){P(OEt)3}4](BPh4)2 (10a)
3375 m
3290 m
3227 m
1668 m
ν(NH)
8.02 m
4.02 m
1.88 s
1.33 t
1.30 t
NH ϩ NH2 ABC2
δA ϭ 131.9
δB ϭ 129.3
δC ϭ 116.8
JAB ϭ 76.1
JAC ϭ 61.4
JBC ϭ 57.3
δA ϭ 134.5
δB ϭ 131.2
δC ϭ 119.3
JAB ϭ 76.8
JAC ϭ 62.0
JBC ϭ 57.3
CH2
CH3
CH3 phos
δ(NH2)
[e]
[e]
9.06 br
NH
ABC2
8.97 m, br
4.26 m
2.91 s
NH2
CH2
CH3
1.38 t
1.37 t
CH3 phos
[e]
{Ru(η2-NHϭC(4-CH3C6H4)ONH2)[P(OEt)3]4}(BPh4)2 (10b) 3381 m
ν(NH)
8.32 m
4.17Ϫ3.94 m
2.46 s
NH ϩ NH2 ABC2
δA ϭ 133.7
δB ϭ 131.1
δC ϭ 118.9
JAB ϭ 75.9
JAC ϭ 61.4
JBC ϭ 57.2
3290 m
3217 m
1653 m
CH2
CH3
CH3 phos
δ(NH2)
1.36 t
1.32 t
1.24 t
9.28 m, br
[e]
NH
8.79 br
4.28 m
2.42 s
1.42 t
1.40 t
1.29 t
NH2
CH2
CH3
CH3 phos
[Ru{η2-NHϭC(CH3)ONH(CH3)}{P(OEt)3}4](BPh4)2 (11)
3408 m
3302 w
1608 m
ν(NH)
7.0 br
4.75 s, br
4.07 m
3.27 s
2.08 s
1.34 t
ϭNH
NH
ABC2
δA ϭ 132.4
δB ϭ 129.7
δC ϭ 120.6
JAB ϭ 6.9
JAC ϭ 58.8
JBC ϭ 60.8
δ(NH2)
CH2
CH3
CH3
CH3 phos
1.30 t
1.28 t
[Os{η2-NHϭC(CH3)ONH2}{P(OEt)3}4](BPh4)2 (12a)
3330 m
3217 w
1668 m
ν(NH)
7.48 s, br
4.08Ϫ6.84 m
2.07 s
NH ϩ NH2
CH2
A2B2
δA ϭ 82.7
δB ϭ 81.0
JAB ϭ 41.5
δ(NH2)
CH3
1.29 t
CH3 phos
1.25 t
12.36 br
[e,g]
[e,g]
NH
A2BC
δA ϭ 86.8
δB ϭ 84.7
δC ϭ 83.8
JAB ϭ 41.5
JAC ϭ 41.0
JBC ϭ 54.2
8.56 s
4.04 m
2.44 s
1.21 t
1.16 t
NH2
CH2
CH3
CH3 phos
[Os{η2-NHϭC(4-CH3C6H4)ONH2}{P(OEt)3}4](BPh4)2 (12b) 3481 m, br ν(NH)
8.38 s, br
4.10Ϫ3.90 m
2.46 s
NH ϩ NH2 A2BC
δA ϭ 81.9
δB ϭ 80.6
δC ϭ 80.4
JAB ϭ 41.5
JAC ϭ 41.6
JBC ϭ 53.8
δA ϭ 82.9
δB ϭ 81.7
δC ϭ 81.6
JAB ϭ 42.3
JAC ϭ 41.5
JBC ϭ 54.3
δA ϭ 83.4
δB ϭ 82.9
δC ϭ 82.1
JAB ϭ 41.5
JAC ϭ 41.9
JBC ϭ 54.5
3310 m
CH2
1636 m
δ(NH2)
CH3
CH3 phos
1.29 t
1.20 t
[g]
[g]
10.12 br
NH
A2BC
A2BC
8.28 s
NH2
4.03Ϫ3.88 m
2.44 s
CH2
CH3
1.23 t
1.15 t
CH3 phos
[e] [g]
[e,g]
11.79 s, br
8.71 s, br
4.17 m
2.38 s
NH
NH2
CH2
CH3
1.29 t
1.22 t
CH3 phos
[Os{η2-NHϭC(CH3)ONH(CH3)}{P(OEt)3}4](BPh4)2 (13)
3408 m
3294 m
1610 m
ν(NH)
7.4 br
5.24 s, br
4.00 m
3.29 s
2.08 s
1.28 t
ϭNH
NH
ABC2
δA ϭ 93.8
δB ϭ 89.3
δC ϭ 82.2
JAB ϭ 4.3
JAC ϭ 45.4
JBC ϭ 46.3
δ(NH2)
CH2
CH3
CH3 phos
1.26 t
1.24 t
[a]
[b]
[e]
[c]
[d]
In KBr pellets.
In CD2Cl2 at 25 °C, unless otherwise noted. Phenyl proton resonances are omitted.
Positive shift downfield
[f]
[g]
from 85% H3PO4. In (CD3)2CO. In polyethylene (far-IR). At Ϫ70 °C.
2848
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Eur. J. Inorg. Chem. 2003, 2845Ϫ2854

Hydroxylamine Complexes of RuII, OsII and IrIII
FULL PAPER
The reaction of [IrH3(PPh3)3] with CF3SO3H proceeds
In the temperature range between ϩ30 and Ϫ80 °C the
also in this case with the evolution of H2 and probable for- 31P{1H} NMR spectra of [IrH2(NH2OH)(PPh3)3]BPh4 (9)
mation of either κ1-OSO2CF3 or pentacoordinate inter- show an A2B multiplet indicating the presence of two mag-
mediates which, on treatment with NH2OH, afford the final netically equivalent phosphanes, different from the third. In
1
hydroxylamine derivative 9. We also attempted to prepare the hydride region, the H NMR spectra also appear as a
bis(hydroxylamine) derivatives by reacting [IrH3(PPh3)3] complicated multiplet, which can be simulated as the XY
sequentially, first with two equivalents of CF3SO3H and part (X, Y ϭ H) of an A2BXY spin system, with the param-
then with NH2OH, but only a mixture of products not con- eters reported in Table 1. On this basis, we can reasonably
taining the NH2OH ligand was isolated.
propose a mer-cis geometry of type IV for our hydride-hy-
droxylamine complex 9.
The hydroxylamine complexes of iridium (5Ϫ8) are yel-
low solids, while 9 is white, and all are stable in air and in
solution in polar organic solvents, where they behave as 1:1
electrolytes.[8] Good analytical data were obtained for all
compounds, and their IR and NMR spectroscopic data
(Table 1) confirm the proposed formulations.
A comparison between the results for the NH2OH com-
plexes and those for related hydrazine NH2NH2 complexes
shows that these two ligands are very similar in their behav-
iour toward metal fragments containing phosphite as sup-
porting ligand. Similar complexes of Ru[6a] and Ir,[6d] con-
taining either NH2NH2 or NH2OH as monodentate ligand,
can be isolated in the solid state. Furthermore, in the case
of iridium only the mixed phosphane-phosphite fragment
IrCl2PL2 can give stable hydrazine complexes, so the hy-
droxylamine derivative can be prepared exclusively with the
same mixed-ligand fragment. Some differences, however,
can be observed with osmium, which allows the synthesis
of only mono-hydroxylamine complexes (3) with P(OEt)3
phosphite ligand, whereas both mono- and bis(hydrazine)
derivatives[6c] [OsH(NH2NH2)P4]ϩ and [Os(NH2NH2)2-
P4]2ϩ can easily be prepared. In every case, although the
comparison is still restricted to a few complexes, it seems
that when a metal fragment is able to bind hydrazine, it can
also coordinate hydroxylamine, affording the corresponding
stable derivatives. Support for this hypothesis comes from
the results on other complexes[3] suggesting a synthetic
pathway for NH2OH derivatives.
The IR spectra show the characteristic ν(NH) bands at
3275Ϫ3213 cmϪ1 and one of medium intensity at
1624Ϫ1607 cmϪ1, attributed to δ(NH2) of the NH2OH li-
gands. The ν(OH) absorption in these complexes is weak
and rather broad, and was unambiguously assigned only for
6 at 3490 cmϪ1. In the spectrum of hydride complex 9 two
weak bands at 2179 and 2130 cmϪ1 are also present. These
were assigned to the ν(IrH) absorption of the two HϪ li-
gands in a mutually cis position.
The presence of the hydroxylamine ligand in complexes
1
5؊9 was further confirmed by the H NMR spectra, which
show the characteristic signal at δ ϭ 5.83Ϫ5.25 ppm of the
NH2 protons of the hydroxylamine ligand. The OH proton
is clearly observed at δ ϭ 3.39 ppm only in the case of 9; in
the other complexes it is probably masked by the methylene
protons of the phosphite ligands.
In the temperature range between ϩ30 and Ϫ80 °C the
31P{1H} NMR spectra of the phosphane-phosphite com-
plexes [IrCl2(NH2OH)PL2]BPh4 (5 and 6) [P ϭ P(OEt3,
PPh(OEt)2; L ϭ PPh3] appear as AB2 multiplets in agree-
ment with the magnetic equivalence of the two PPh3 li-
gands. Taking into account that the far-IR spectrum of 5
shows only one ν(IrCl) band at 393 cmϪ1, indicating that
the two ClϪ ligands are in a mutually trans position, we
may propose a mer-trans geometry (III) for our hy-
droxylamine derivatives 5 and 6 (Chart 1).
O-Iminoacylated Hydroxylamine Complexes
The synthesis of hydroxylamine complexes by substitut-
ing a labile ligand has prompted us to extend these studies
to other precursors, such as the nitrile complexes
[M(RCN)2P4]2ϩ with the aim of testing whether new hy-
droxylamine derivatives may be prepared. Surprisingly, the
reaction of bis(nitrile) complexes of ruthenium and osmium
with hydroxylamine does not produce NH2OH complexes,
but affords a yellow solid which was characterised as con-
taining an O-iminoacylated ligand of the type shown in
Scheme 5.
The 31P{1H} NMR spectra of the related arsane com-
plexes [IrCl2(NH2OH)PL2]BPh4 (7 and 8) [P ϭ P(OEt)3,
PPh(OEt)2; L ϭ AsPh3] show only one singlet at δ ϭ 32.8
and 64.3 ppm, respectively, for the phosphite ligand, and
therefore no plausible hypothesis for the geometry of com-
plexes can be made. However, taking into account that the
far-IR spectra show only one ν(IrCl) band, we propose, by
Scheme 5. P ϭ P(OEt)3, M ϭ Ru 10, Os 12, R ϭ CH3 a, 4-
CH3C6H4 b
The reaction proceeds easily at room temperature, afford-
analogy with the related complexes 5 and 6, a mer-trans ing complexes 10 and 12 in good yields. However, only the
geometry (III) for compounds 7 and 8 as well. P(OEt)3-containing O-iminoacylated complexes were pre-
Eur. J. Inorg. Chem. 2003, 2845Ϫ2854
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2849

G. Albertin, S. Antoniutti, S. Beraldo, F. Chimisso
FULL PAPER
Table 2. 13C{1H} NMR spectroscopic data for selected complexes[a]
Compd.
δ
Assignment
[Ru(η2-NHϭC(CH3)ONH2){P(OEt)3}4](BPh4)2 (10a)
[Ru{η2-NHϭC(CH3)ONH(CH3)}{P(OEt)3}4](BPh4)2 (11)
172.8 s
163Ϫ122 m
63.4 m
15.9 s
16.1 m
CϭN
Ph
CH2
CH3Cϭ
CH3 phos
154.7 s
164Ϫ121 m
61.9 m
39.2 s
19.3 s
15.9 m
CϭN
Ph
CH2
CH3N
CH3Cϭ
CH3 phos
[Os{η2-NHϭC(4-CH3C6H4)ONH2}{P(OEt)3}4](BPh4)2 (12b)
156.3 s
165Ϫ122 m
62.6 m
CϭN
Ph
CH2
21.3 s
15.8 m
CH3 p-tolyl
CH3 phos
[a]
In (CD3)2CO at 203 K.
pared in pure form, while with the related PPh(OEt)2 com- δ ϭ 156.3 ppm for 12b. An HMBC experiment for com-
pounds only intractable mixtures of product were obtained. pound 10a correlates the imine carbon signal at δ ϭ
Compounds 10 and 12 are pale-yellow solids stable in air 172.8 ppm with the methyl proton resonances at δ ϭ
and in solution in polar organic solvents, diamagnetic and 2.91 ppm of the methyl group bonded to the iminic C1 car-
1:1 electrolytes.[8] The analytical and spectroscopic data (IR bon atom, in agreement with the proposed assignment.
and NMR, Table 1 and 2) support the proposed formu-
In the osmium complex 12b the HMBC experiment
lation. The infrared spectra show, in the 3481Ϫ3217 cmϪ1 shows a correlation between the iminic C1 carbon reson-
region, two or three medium-intensity bands, attributed to ance and the signals of the phenyl protons of the p-tolyl
ν(NH) of the η2-HNϭC(R)ONH2 ligand. The δ(NH2) ab- substituent. On the basis of these data, and taking into ac-
sorptions at 1668Ϫ1636 cmϪ1 also appear in the spectra. count that in any solvent and in the temperature range be-
1
At room temperature, in CD2Cl2 as solvent, the H NMR tween ϩ20 and Ϫ80 °C the 31P{1H} NMR spectra of the
spectra of complexes 10 and 12 show, in the high-frequency O-iminoacylated derivatives 10, 12 appear as an ABC2 or
region, a broad resonance at δ ϭ 8.32Ϫ7.84 ppm. In A2BC multiplet, a type-V geometry can reasonably be pro-
(CD3)2CO, however, this resonance splits into two slightly posed.
broadened signals at
8.97Ϫ8.28 ppm, respectively, of intensity ratio 1:2. This droxylamines and treated the bis(nitrile) complexes
split is observed at room temperature, except for compound [M(CH3CN)2P4]2ϩ
with N-methylhydroxylamine
δ
ϭ
12.36Ϫ9.06 and at
We then thought to extend the studies to other hy-
12a, for which a lowering of the temperature to Ϫ20 °C is NH(CH3)OH. We observed that the reaction proceeds as
required. The highest frequency signal is assigned to the with NH2OH to give the chelated [M(η2-HNϭ
iminic ϭNH proton (H1), while the lowest is assigned to C(CH3)ONH(CH3)}P4]2ϩ cations 11 and 13, which were
Ϫ
the ONH2 (H2) group of the O-iminoacylated ligand. In isolated as their BPh4 salts and characterised (Scheme 6).
1
the H NMR spectra one sharp singlet between δ ϭ 1 and
3 ppm due to the methyl group of the substituent R (CH3
or 4-CH3C6H4) of the η2-ligand is also present.
Support for these assignments comes from a H COSY
1
spectrum of compound 10a, which shows that the iminic
HNϭ proton (H1) correlates with the methyl substituent
of the iminic carbon atom HNϭC(CH3) of the ligand. No
correlation was observed between the iminic H1 and the
aminic H2 proton resonances, in agreement with an O-im-
inoacylated molecule.
Scheme 6. P ϭ P(OEt)3, M ϭ Ru 11, Os 13
The 13C NMR spectra confirm the formulation of the
complexes showing, apart from the signals of the P(OEt)3
and the BPh4 anion, the imine carbon (C1) resonance of
The IR spectra of complexes 11 and 13 show the charac-
the η2-ligand as a singlet at δ ϭ 172.8 ppm for 10a and at teristic ν(NH) absorption at 3408Ϫ3294 cmϪ1 and
2850
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Hydroxylamine Complexes of RuII, OsII and IrIII
FULL PAPER
δ[NH(CH3)] at 1610Ϫ1608 cmϪ1 for the HNϭ coordinated nitrile. Doubts remain, however, regarding the
C(CH3)ONH(CH3) ligand. reaction path. Treatment of bis(nitrile) complexes
1
In the H NMR spectra (Table 1) of both compounds 11 [M(RCN)2P4]2ϩ with NH(R1)OH (R1 ϭ H, CH3) could re-
and 13 two singlets between δ ϭ 3.29 and 2.08 ppm appear, sult in the substitution of only one nitrile ligand to afford
due to the two methyl groups of the η2-ligand. One broad the [M(RCN)(NH2OH)P4]2ϩ intermediate A. The O-imino-
signal at δ ϭ 4.75 ppm (11) and at δ ϭ 5.24 ppm (13) is also acylated hydroxylamine complex can be obtained
present in the spectra, which was attributed to the aminic (Scheme 7) by a nucleophilic attack of the coordinated hy-
1
ONHCH3 (H2) proton. A H COSY spectrum of 11 con- droxylamine’s oxygen atom on the coordinated RCN’s ni-
firms this assignment, showing a strong correlation between trile carbon atom, followed by an H-shift.
the signal at δ ϭ 4.75 ppm and the methyl singlet at δ ϭ
2.08 ppm of CH3N2. A weak correlation was also observed
between the other methyl singlet at δ ϭ 3.27 ppm (CH3C1)
and a signal near δ ϭ 7.0 ppm, which appears to be masked
by the phenyl protons of the BPh4 anion and can be attri-
buted to the iminic proton (H1) of the ligand.
The 13C{1H} NMR spectrum of 11 (Table 2) shows, be-
sides the signals of the phosphites and the BPh4 anion, two
singlets at δ ϭ 39.2 and 19.3 ppm attributed to the two
methyl carbons of the N2CH3 and C1CH3 groups, respec-
tively, and one singlet at δ ϭ 154.7 ppm due to the iminic
CϭN carbon atom (C1). An HMBC experiment confirms
this attribution showing a strong correlation between the
Scheme 7. P ϭ P(OEt)3, R ϭ CH3, 4-CH3C6H4, R1 ϭ H, CH3
imino carbon signal at δ ϭ 154.7 ppm and the proton signal
at δ ϭ 2.08 ppm of the methyl N2CH3 substituent and also
1
a weak correlation with the H signal at δ ϭ 3.27 ppm of
the C1CH3 methyl group. Furthermore, the methyl carbon
resonance of the HNϭCCH3 group at δ ϭ 19.3 ppm corre-
lates with the aminic H2 proton signal at δ ϭ 4.75 ppm, in
agreement with the presence of the O-iminoacylated ligand.
In the temperature range between ϩ30 and Ϫ80 °C, the
31P{1H} NMR spectra of both the ruthenium and osmium
complexes 11 and 13 appear as ABC2 multiplets; these spec-
tra can be simulated with the parameters reported in
Table 1. On the basis of these data, we can reasonably pro-
pose a geometry of type VI for our O-iminoacylated meth-
ylhydroxylamine derivatives.
The hydroxylamine, however, could react with one of the
coordinated nitriles through the oxygen atom without being
bonded to the central metal, resulting in the O-iminoacyl-
ated ligand, which, by substitution of the second RCN li-
gand, yields the final chelate complexes (Scheme 8).
Formation of O-iminoacylated hydroxylamine complexes
from the reaction of a coordinated nitrile with NH2OH or
NH(CH3)OH is not surprising, taking into account that a
metal-bonded RCN molecule can undergo nucleophilic
attack by alcohols, amines and carbanions to give imino-
ether-, amidine- and imine derivatives.[7,9Ϫ12] Furthermore,
nitrile precursors [Ru(RCN)2P4]2ϩ are reported[6aϪ6c] to re-
act with hydrazine or methylhydrazine to give amidrazone
complexes [M{η2-NHϭC(R)N(R1)NH2}P4]2ϩ (R1 ϭ H,
CH3), probably through the nucleophilic attack of the hy-
drazine on the cyanide carbon atom of the coordinated ni-
triles, followed by an H-shift, giving a five-membered metal- Scheme 8
lacycle. Finally, it is well documented[13Ϫ15] that NH2OH
can react with free nitriles through the more usual N-ad-
dition, giving amide oximes RC(NH2)ϭNOH, or through
O-addition, affording carboxamides RC(ϭO)NH2 as the fi-
nal products.
The formation of complexes 10Ϫ13, in fact, means that
hydroxylamine, which possesses two sites of attack, reacts
A nucleophilic attack of the hydroxylamine by the oxygen with the coordinated nitrile through the oxygen atom. The
atom on the coordinated nitrile can therefore also be pro- N-addition of hydroxylamine should give different prod-
posed in our case for the formation of O-iminoacylated hy- ucts, such as complexes containing either the imine NHϭ
droxylamine complexes 10Ϫ13, which represents the first C(R)NHOH or the tautomer amide oxime RC(NH2)ϭ
example[7] of the addition of hydroxylamine NH2OH to a NOH as a ligand (Scheme 9).
Eur. J. Inorg. Chem. 2003, 2845Ϫ2854
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2851

G. Albertin, S. Antoniutti, S. Beraldo, F. Chimisso
FULL PAPER
ing the first bis(hydroxylamine) [Ru(NH2OH)2P4](BPh4)2
derivatives. The preparation of O-iminoacylated complexes
[M{η1-HNϭC(R)ONHR1}P4](BPh4)2 (M ϭ Ru, Os) was
also achieved by O-addition of hydroxylamine to an orga-
nonitrile in a metal-assisted reaction.
Experimental Section
General: All synthetic work was carried out under an inert atmos-
phere using standard Schlenk techniques or a Vacuum Atmosphere
dry-box. Once isolated, the complexes were found to be relatively
stable in air, but were stored under an inert atmosphere at Ϫ25 °C.
All solvents were dried over appropriate drying agents, degassed
on a vacuum line and distilled into vacuum-tight storage flasks.
The phosphite P(OEt)3 (Aldrich) was purified by distillation under
nitrogen, while PPh(OEt)2 was prepared by the method of Rabi-
nowitz and Pellon.[17] RuCl3·3H2O was obtained from Chempur,
while [(NH4)2(OsCl6)] was purchased from Johnson Matthey and
IrCl3·3H2O from Pressure Chemical Co.; all salts were used as re-
ceived. Hydroxylamine (NH2OH) and N-methylhydroxylamine
[NH(CH3)OH] were prepared by slight modification of a reported
method,[18] involving treatment of hydroxylamine hydrochloride
with sodium ethoxide in ethanol. The free NH2OH was isolated as
a white solid, while NH(CH3)OH was prepared in solution just
prior to use. Other reagents were purchased from commercial
sources in the highest available purity and used as received. Infra-
red spectra were recorded on a Nicolet Magna 750 FT-IR spectro-
photometer. NMR spectra (1H, 13C, 31P) were obtained on Bruker
AC200 and AVANCE 300 spectrometers at temperatures varying
Scheme 9
We have studied the reactions between [M(RCN)2P4]2ϩ
cations and hydroxylamine by NMR spectroscopy and ob-
served that no signals attributable to a nitrile-hydroxylam-
ine intermediate of the type [M(RCN)(NH2OH)P4]2ϩ were
detected, with the resonances of the initial and the final
products and of free nitrile being the only signals observed
in the spectra. However, since the reaction of this intermedi-
ate would be intramolecular, one could expect it to be much
faster than substitution of one RCN to give
[M(RCN)(NH2OH)P4]2ϩ, making this intermediate unde-
tectable. On this basis, although our data do not give con-
clusive information, a mechanism involving the initial sub-
stitution of one RCN with NH2OH (Scheme 7) may be
reasonably proposed.
1
between Ϫ90 °C and ϩ30 °C, unless otherwise noted. H and 13C
spectra are referred to internal tetramethylsilane, while 31P{1H}
chemical shifts are reported with respect to 85% H3PO4, with
downfield shifts considered positive. The SWAN-MR software
package[19] was used to treat NMR spectroscopic data and for the
simulation. The conductivity of 10Ϫ3  solutions of the complexes
in CH3NO2 at 25 °C was measured with a Radiometer CDM 83 in-
strument.
Apart from the mechanism, the behaviour of both the
hydroxylamine and the hydrazine toward a coordinated ni-
trile of the [M(RCN)2P4]2ϩ cations containing P(OEt)3 as
ancillary ligand is very similar. In both cases they result in
a nucleophilic attack on the nitrile carbon atom followed
by an H-shift, yielding a new chelate ligand. A different
atom, however, is used by the two nucleophiles, i.e. N-ad-
dition with hydrazine and O-addition with hydroxylamine,
affording different molecules which behave, in every case,
as bidentate ligands. The attack of the oxygen atom of the
hydroxylamine in these reactions is rather surprising, since
the reaction with free nitriles involves, in the majority of
cases, N-addition.[13Ϫ15] An O-addition has been re-
ported[16] in the reaction of the platinum complex
[PtCl4(CH3CN)2] with N-substituted hydroxylamine
R2NOH, but the steric hindrance at the N-atom makes the
Preparation of the Complexes: The hydride complexes RuH2P4 and
OsH2P4 and the nitrile complexes [Ru(RCN)2P4](BPh4)2 and
[Os(RCN)2P4](BPh4)2 [R ϭ CH3, 4-CH3C6H4; P ϭ P(OEt)3,
PPh(OEt)2] were prepared following the reported methods.[6,20] The
iridium complexes [IrHCl2P(PPh3)2], [IrHCl2P(AsPh3)2] [P ϭ
P(OEt)3, PPh(OEt)2] and [IrH3(PPh3)3] were synthesised by pub-
lished methods.[6d,21]
[RuH(NH2OH)P4]BPh4 [P ؍ P(OEt)3 1, PPh(OEt)2 2]: An equi-
molar amount of CF3SO3H (0.40 mmol, 35 µL) was added to a
O-attack plausible in this case. This is the only known ex- solution of the appropriate hydride RuH2P4 (0.40 mmol) in 10 mL
ample[16] of the reaction of a substituted hydroxylamine
with coordinated RCN. In our [M(RCN)2P4]2ϩ complexes
the coordination of the nitrile to the MP4 fragment prob-
ably makes the nitrile carbon increasingly susceptible to nu-
cleophilic attack by the more electronegative oxygen, yield-
ing the O-iminoacylated derivatives.
of ethanol cooled to Ϫ196 °C and the reaction mixture, after warm-
ing to 0 °C, was stirred for 1 h. An excess of hydroxylamine
(0.60 mmol, 0.43 mL of a 1.4  solution in ethanol) was then added
and the resulting solution stirred for about 2 h. The solvent was
removed under reduced pressure to give an oil, which was treated
with ethanol (2 mL) containing an excess of NaBPh4 (0.8 mmol,
0.27 g). A white solid slowly separated out upon stirring the re-
sulting solution. This solid was filtered off and recrystallised from
CH2Cl2 and ethanol; yield 336 mg for 1 (75%); 384 mg for 2 (77%).
1: C48H84BNO13P4Ru (1118.97): calcd. C 51.52, H 7.57, N 1.25;
Conclusions
found C 51.41, H 7.60, N 1.18. ΛM ϭ 57.4 S cm2 molϪ1
2: C64H84BNO9P4Ru (1247.14): calcd. C 61.64, H 6.79, N 1.12;
.
In this contribution we have reported the synthesis of sev-
eral new hydroxylamine complexes of Ru, Os and Ir, includ- found C 61.48, H 6.82, N 1.17. ΛM ϭ 58.6 S cm2 molϪ1
.
2852
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Hydroxylamine Complexes of RuII, OsII and IrIII
FULL PAPER
[OsH(NH2OH){P(OEt)3}4]BPh4 (3): An equimolar amount of
and stirred for 10 min. An excess of hydroxylamine (1.20 mmol,
CF3SO3CH3 (0.12 mmol, 11 µL) was added to a solution of 1.46 mL of 0.82  solution in ethanol) was added and the solution
[OsH2{P(OEt)3}4] (0.12 mmol, 0.100 g) in 5 mL of toluene cooled
to Ϫ196 °C and the reaction mixture, after warming to room tem-
stirred for 4 h. The solvent was removed under reduced pressure to
give an oil, which was triturated with ethanol (3 mL) containing an
perature, was stirred for 1 h. An excess of NH2OH (0.3 mmol, excess of NaBPh4 (0.24 mmol, 0.082 g). A white solid separated out
0.48 mL of a 0.63  solution in ethanol) was added and the solu-
tion stirred for about 4 h. The solvent was then removed under
reduced pressure to give an oil which was treated with ethanol
from the resulting solution, which was filtered off and recrystallised
from CH2Cl2 and ethanol; yield 128 mg (80%). C78H70BIrNOP3
(1333.37): calcd. C 70.26, H 5.29, N 1.05; found C 70.35, H 5.37,
(2 mL) containing an excess of NaBPh4 (0.24 mmol, 0.082 g). N 1.11. ΛM ϭ 54.8 S cm2 molϪ1
.
Upon stirring the resulting solution, a white solid separated out
[Ru{η2-NH؍C(R)ONH2}{P(OEt)3}4](BPh4)2 (R ؍ CH3 10a, 4-
CH3C6H4 10b): An excess of NH2OH (0.52 mmol, 0.62 mL of a
0.84  solution in ethanol) was added to a solution of the appropri-
ate nitrile complex [Ru(RCN)2{P(OEt)3}4](BPh4)2 (0.13 mmol) in
10 mL of CH2Cl2 and the reaction mixture was stirred for 24 h.
The solvent was removed under reduced pressure to give an oil
which was treated with ethanol (2 mL). The addition of an excess
of NaBPh4 (0.26 mmol, 0.089 g) in 2 mL of ethanol to the resulting
solution caused the separation of a white solid, which was filtered
off and recrystallised from CH2Cl2 and ethanol; yield 123 mg (64%)
for 10a; 135 mg (67%) for 10b.
which was filtered off and recrystallised from CH2Cl2 and ethanol;
yield 104 mg (72%). C48H84BNO13OsP4 (1208.10): calcd. C 47.72,
H 7.01, N 1.16; found C 47.89, H 7.08, N 1.09. ΛM ϭ 55.0
S cm2 molϪ1
.
[Ru(NH2OH)2{P(OEt)3}4](BPh4)2 (4): An equimolar amount of
CF3SO3H (0.40 mmol, 35 µL) was added to a solution of
[RuH2{P(OEt)3}4] (0.40 mmol, 0.307 g) in 10 mL of toluene cooled
to Ϫ196 °C. The reaction mixture was warmed to 0 °C, stirred for
1 h, and then cooled to Ϫ196 °C again. Triflic acid (0.40 mmol, 35
µL) was added and the solution, after warming to 0 °C, was stirred
for 90 min. An excess of hydroxylamine (1.60 mmol, 1.14 mL of a
1.4  solution in ethanol) was then added and the solution stirred
for about 20 min. The solvent was removed under reduced pressure
to give an oil which was treated with ethanol (2 mL). Addition of
an excess of NaBPh4 (1.60 mmol, 0.55 g) in ethanol (2 mL) to the
resulting solution caused the separation of a white solid, which was
filtered off and recrystallised from CH2Cl2 and ethanol; yield
476 mg (81%). C72H106B2N2O14P4Ru (1470.22): calcd. C 58.82, H
7.27, N 1.47; found C 58.65, H 7.38, N 1.58. ΛM ϭ 119.6
S cm2 molϪ1).
10a: C74H106B2N2O13P4Ru (1478.24): calcd. C 60.13, H 7.23, N
1.90; found C 59.97, H 7.17, N 1.86. ΛM ϭ 117.4 S cm2 molϪ1
.
10b: C80H110B2N2O13P4Ru (1554.34): calcd. C 61.82, H 7.13, N
1.80; found C 61.98, H 7.20, N 1.75. ΛM ϭ 120.7 S cm2 molϪ1
.
[Ru{η2-NH؍C(CH3)ONH(CH3)}{P(OEt)3}4](BPh4)2 (11): This
complex was prepared similarly to 10 by reacting
[Ru(CH3CN)2{P(OEt)3}4](BPh4)2 (0.17 mmol, 0.250 g in 10 mL of
CH2Cl2) with an excess of NH(CH3)OH (1.7 mmol, 2.9 mL of 0.58

solution in ethanol) for 24 h; yield 140 mg (55%).
C75H108B2N2O13P4Ru (1492.27): calcd. C 60.37, H 7.29, N 1.88;
found C 60.49, H 7.35, N 1.80. ΛM ϭ 119.1 S cm2 molϪ1
[IrCl2(NH2OH)P(PPh3)2]BPh4 [P ؍ P(OEt)3 5, PPh(OEt)2 6]: An
equimolar amount of CF3SO3H (0.12 mmol, 11 µL) was added to
a solution of the appropriate hydride [IrHCl2P(PPh3)2] (0.12 mmol)
in 8 mL of CH2Cl2 cooled to Ϫ196 °C, and the reaction mixture
was warmed to room temperature and stirred for 90 min. An excess
of hydroxylamine (1.20 mmol, 1.46 mL of 0.82  solution in etha-
nol) was added and the resulting mixture stirred for about 4 h. The
solvent was removed under reduced pressure giving an oil, which
was triturated with ethanol (2 mL) containing an excess of NaBPh4
(0.24 mmol, 0.082 g). A yellow solid slowly separated out from the
resulting solution, which was filtered off and recrystallised from
CH2Cl2 in ethanol; yield 98 mg (63%) for 5; 109 mg (68%) for 6.
5: C66H68BCl2IrNO4P3 (1306.12): calcd. C 60.69, H 5.25, N 1.07,
Cl 5.43; found C 60.55, H 5.32, N 1.06, Cl 5.37. ΛM ϭ 58.2
.
[Os{η2-NH؍C(R)ONH2}{P(OEt)3}4](BPh4)2 (R ؍ CH3 12a, 4-
CH3C6H4 12b): An excess of hydroxylamine (1.3 mmol, 1.8 mL of
a 0.72  solution in ethanol) was added to a solution of the appro-
priate nitrile complex [Os(RCN)2{P(OEt)3}4](BPh4)2 (0.13 mmol)
in 8 mL of CH2Cl2 and the reaction mixture stirred for 20 h. The
solvent was removed under reduced pressure to give an oil, which
was treated with ethanol (2 mL) containing an excess of NaBPh4
(0.26 mmol, 0.089 g). Upon stirring the resulting solution a white
solid slowly separated out, which was filtered off and recrystallised
from CH2Cl2 and ethanol; yield 124 mg (62%) for 12a; 126 mg
(59%) for 12b.
12a: C74H106B2N2O13OsP4 (1567.37): calcd. C 56.71, H 6.82, N
S cm2 molϪ1
.
1.79; found C 56.59, H 6.98, N 1.68. ΛM ϭ 123.4 S cm2 molϪ1
.
6: C70H68BCl2IrNO3P3 (1338.17): calcd. C 62.83, H 5.12, N 1.05,
Cl 5.30; found C 63.01, H 5.24, N 1.10, Cl 5.08. ΛM ϭ 61.6
12b: C80H110B2N2O13OsP4 (1643.47): calcd. C 58.47, H 6.75, N
1.70; found C 58.30, H 6.81, N 1.62. ΛM ϭ 121.6 S cm2 molϪ1
.
S cm2 molϪ1
.
[Os{η2-NH؍C(CH3)ONH(CH3)}{P(OEt)3}4](BPh4)2 (13): This
complex was prepared similarly to 12 by reacting
[Os(CH3CN)2{P(OEt)3}4](BPh4)2 with a 10-fold excess of N-meth-
ylhydroxylamine; yield 93 mg (45%). C75H108B2N2O13OsP4
(1581.40): calcd. C 56.96, H 6.88, N 1.77; found C 57.13, H 6.96,
[IrCl2(NH2OH)P(AsPh3)2]BPh4 [P ؍ P(OEt)3 7, PPh(OEt)2 8]:
These complexes were prepared exactly as for compounds 5 and 6;
yield 113 mg (68%) for 7; 125 mg (73%) for 8.
7: C66H68As2BCl2IrNO4P (1394.02): calcd. C 56.87, H 4.92, N 1.00,
Cl 5.09; found C 56.64, H 5.01, N 0.92, Cl 5.27. ΛM ϭ 55.7
N 1.69. ΛM ϭ 115.9 S cm2 molϪ1
.
S cm2 molϪ1
.
8: C70H68As2BCl2IrNO3P (1426.07): calcd. C 58.96, H 4.81, N 0.98,
Cl 4.97; found C 59.13, H 4.70, N 1.06, Cl 4.79. ΛM ϭ 59.0
S cm2 molϪ1
.
Acknowledgments
[IrH2(NH2OH)(PPh3)3]BPh4 (9): An equimolar amount of
CF3SO3H (0.12 mmol, 11 µL) was added to a solution of
[IrH3(PPh3)3] (0.12 mmol, 0.118 g) in 5 mL of toluene cooled to
Ϫ196 °C, and the reaction mixture warmed to room temperature
The financial support of MIUR (Rome) Programmi di Ricerca
Scientifica di Rilevante Interesse Nazionale, Cofinanziamento
2002Ϫ2003 is gratefully acknowledged. We thank Daniela Baldan
for technical assistance.
Eur. J. Inorg. Chem. 2003, 2845Ϫ2854
www.eurjic.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2853

G. Albertin, S. Antoniutti, S. Beraldo, F. Chimisso
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Received February 3, 2003
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Eur. J. Inorg. Chem. 2003, 2845Ϫ2854