148
H.-C. Bo¨ttcher et al. / Journal of Organometallic Chemistry 628 (2001) 144–150
is shown in Fig. 3, selected bond lengths and angles are
summarized in Table 4. The molecule consists of a
diruthenium core bridged by a phosphido group, a
dppm ligand and a nitrosyl group. The MꢁM distance
4.1. Synthesis of [M2(CO)4(v-H)2(v-PtBu2)-
(v-dppm)][BF4] (M=Fe, 1a; M=Ru, 2a)
In a typical reaction, a solution of [M2(CO)4(m-H)(m-
PtBu2)(m-dppm)] (380 mg, 0.50 mmol 1; 420 mg, 0.50
mmol 2) in 20 ml of Et2O was treated with a few drops
of tetrafluoroboric acid (aqueous, 40%) to give a dark
redviolet precipitate after 10 min in the case of 1a and
a bright yellow precipitate immediately in the case of
2a. The solid was filtered off and washed with 20 ml of
Et2O and dried in vacuo (380 mg 1a, 90%, m.p. 170°C;
410 mg 2a, 87%, m.p. 248°C).
,
of 2.7552(7) A indicates a RuꢁRu single bond and
agrees well with the RuꢁRu bonds found in the other
similar constituted complexes [2–4]. A comparison of
the structural data of 4 with the molecular structures of
other diruthenium species with bridging NO ligands is
complicated since X-ray crystal structure data of only
one compound, namely [Ru2Cp*(m-NO)2Cl2] (5), are
2
available. An inspection of these data yields a good
agreement of the corresponding bond lengths and an-
gles. Thus the following data of 5 agree well with those
1a: Anal. Found: C, 53.12; H, 5.37; P, 10.87. Calc.
for C37H42BF4Fe2O4P3 (MW 842.16): C, 52.77; H, 5.03;
P, 11.03% — 1H-NMR (CDCl3): l 7.32 (m, 20H,
C6H5), 3.51 (m, br, 2H, PꢁCH2ꢁP), 1.51 (d, 18H, tC4H9,
3JPH=12.3 Hz), −21.48 (m, br, 2H, m-H) — 31P{1H}-
in
4 (see Table 4), for 5: d(RuꢁRu)=2.684(2),
,
RuꢁN(1)=1.96,
N(1)ꢁO(1)=135.1(8)° [9].
N(1)ꢁO(1)=1.21
A;
Ru(1)ꢁ
2
NMR (CDCl3): l 278.93 (t, br, m-P, JPP=79.0 Hz),
63.10 (d, br, m-dppm, 2JPP=79.0 Hz) — IR, (KBr,
cm−1) w(CO) 2047s, 2025vs, 2003s, 1986vs — MS: 755
[M−BF4]+; 727 [M−BF4−CO]+; 699 [M−BF4−
2CO]+; 671 [M−BF4−3CO]+; 643 [M−BF4−
4CO]+.
3. Conclusions
The dimetal vector in the coordinatively unsaturated
compounds [M2(CO)4(m-H)(m-PtBu2)(m-dppm)] (MꢀFe,
1; MꢀRu, 2) is readily protonated by the strong acid
HBF4 to give the two-fold m-hydrido bridged complexes
[M2(CO)4(m-H)2(m-PtBu2)(m-dppm)][BF4] (1a, 2a) in al-
most quantitative yields. The hydrides in 1a and 2a are
acidic, being rapidly deprotonated by the base DBU
yielding the starting complexes 1 and 2, respectively.
An analogous reaction behaviour is observed for the
compound [Ru2(CO)4(m-Cl)(m-PtBu2)(m-dppm)] (3). The
acid–base character of these reactions could be used for
the synthesis of [Ru2(CO)4(m-NO)(m-PtBu2)(m-dppm)]
(4) via deprotonation of [Ru2(CO)4(m-H)(m-NO)(m-
PtBu2)(m-dppm)][BF4] (4a) with the base DBU because
attempts to prepare 4 in a clean reaction of 2 with nitric
oxide or other sources of NO failed up to now.
2a: Anal. Found: C, 47.43; H, 4.09; P, 10.32. Calc.
for C37H42BF4O4P3Ru2 (MW 932.61): C, 47.65; H, 4.54;
1
P, 9.96% — H-NMR (CD3COCD3): l 7.50 (m, 20H,
t
C6H5), 3.89 (m, 2H, PꢁCH2ꢁP), 1.54 (d, 18H, C4H9,
3JPH=15.5 Hz), −13.48 (m, 2H, m-H) — 31P{1H}-
2
NMR (CD3COCD3): l 253.89 (t, m-P, JPP=146.4 Hz),
46.46 (d, m-dppm, 2JPP=146.4 Hz) — IR (KBr, cm−1):
w(CO) 2067s, 2048vs, 2021s, 2002vs — MS: 846 [M−
BF4]+; 818 [M−BF4−CO]+; 790 [M−BF4−2CO]+;
762 [M−BF4−3CO]+; 734 [M−BF4−4CO]+.
4.2. Synthesis of [Ru2(CO)4(v-H)(v-Cl)(v-PtBu2)-
(v-dppm)][BF4] (3a)
A
solution of [Ru2(CO)4(m-Cl)(m-PtBu2)(m-dppm)]
(440 mg, 0.50 mmol 3) in 80 ml of Et2O was treated
with a few drops of tetrafluoroboric acid (aqueous,
40%) to give a pale yellow precipitate immediately. The
solid obtained was filtered off and washed with 20 ml of
Et2O and dried in vacuo (440 mg, 92%, m.p. 220°C).
3a: Anal. Found: C, 46.32; H, 4.51; Cl, 3.96. Calc.
for C37H41BClF4O4P3Ru2 (MW 967.05): C, 45.96; H,
4. Experimental
All reactions were performed under Ar atmosphere
using conventional Schlenk techniques. Solvents were
dried over sodium–benzophenone ketyl or molecular
sieves and were distilled under Ar prior to use. Starting
materials were either commercially available or were
prepared as described before [2,3]. IR spectra were
obtained using a Mattson 5000 instrument. The NMR
spectra were recorded on Gemini 200 (Varian) or Unity
500 (Varian) spectrometers. Solvent signals (1H) and
85% H3PO4 (31P) were used as references. The mass
spectra were obtained on the instrument AMD 402.
Elemental analyses were carried out at the Microanalyt-
ical Laboratory of the Chemical Department, Univer-
sity of Halle.
1
4.27; Cl, 3.67% — H-NMR (CDCl3): l 7.41 (m, 20H,
2
C6H5), 2.78 (t, 2H, PꢁCH2ꢁP, JPH=10.4 Hz), 1.61 (d,
t
3
t
3
9H, C4H9, JPH=14.6 Hz), 1.50 (d, 9H, C4H9, JPH
=
2
14.8 Hz), −12.58 (dt, 1H, m-H, JPH=15.6, 23.6 Hz)
2
—
31P{1H}-NMR (CDCl3): l 261.10 (t, m-P, JPP
=
2
173.3 Hz), 44.72 (d, m-dppm, JPP=173.3 Hz) — IR
(KBr, cm−1): w(CO) 2076s, 2065vs, 2017s, 1999vs —
MS: 881 [M−BF4]+; 853 [M−BF4−CO]+; 825 [M−
BF4−2CO]+; 797 [M−BF4−3CO]+; 769 [M−
BF4−4CO]+.
B?ttcher, Hans-Christian
