Heterometallic complexes with borole ligands

Article abstract of DOI:10.1039/a903846i

The borole-containing carbonylmetalates [(η-C₄H₄BPh)Re(CO)₃]^- ([Re]^-) and [(η-C₄H₄BPh)Fe(CO)₂H]^- ([Fe]^-) were used for the synthesis of heterometallic complexes with Re-Hg, Re-Cu, Re-Ag, Re-Au or Fe-Pt metal-metal bonds, respectively. The complex [Re]-Hg-[Re] 1 was characterized by X-ray diffraction and contains a linear metal chain. In the presence of HgCl₂, redistribution reactions were observed, leading to [Re]-Hg-Cl 2 which was independently prepared from [Re]^- and an excess of HgCl₂. The reaction of [Fe]^- with trans-[PtBr₂(4-Mepy)₂] (4-Mepy = 4-methylpyridine) afforded the trinuclear complex trans-[Pt[Fe]₂(4-Mepy)₂] 6 which was characterized by X-ray diffraction and contains two hydrido ligands which bridge the Fe-Pt bonds.

Full text of DOI:10.1039/a903846i

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Heterometallic complexes with borole ligands†‡
Pierre Braunstein,*a Ulli Englert,b Gerhard E. Herberich,*b Mark Neuschütza,b and
Martin U. Schmidtb
a Laboratoire de Chimie de Coordination, UMR 7513 CNRS, Université Louis Pasteur,
67070 Strasbourg Cédex, France. E-mail: braunst@chimie.u-strasbg.fr
b Institut für Anorganische Chemie der Rheinisch-Westfälischen Technischen Hochschule Aachen,
Prof. Pirlet Str. 1, 52074 Aachen, Germany
Received 13th May 1999, Accepted 23rd June 1999
The borole-containing carbonylmetalates [(η-C4H4BPh)Re(CO)3]Ϫ ([Re]Ϫ) and [(η-C4H4BPh)Fe(CO)2H]Ϫ ([Fe]Ϫ) were
used for the synthesis of heterometallic complexes with Re–Hg, Re–Cu, Re–Ag, Re–Au or Fe–Pt metal–metal bonds,
respectively. The complex [Re]–Hg–[Re] 1 was characterized by X-ray diffraction and contains a linear metal chain.
In the presence of HgCl2, redistribution reactions were observed, leading to [Re]–Hg–Cl 2 which was independently
prepared from [Re]Ϫ and an excess of HgCl2. The reaction of [Fe]Ϫ with trans-[PtBr2(4-Mepy)2] (4-Mepy =
4-methylpyridine) afforded the trinuclear complex trans-[Pt[Fe]2(4-Mepy)2] 6 which was characterized by X-ray
diffraction and contains two hydrido ligands which bridge the Fe–Pt bonds.
The isolobal analogy between the borole dianion (C4H4BR)2Ϫ
(R = Ph) and the cyclopentadienide ion (C5H5)Ϫ may be used
to compare the reactivity and bonding capabilities of organo-
metallic reagents of two adjacent columns of the Periodic
classification (e.g. [(η-C4H4BR)Re(CO)3]Ϫ and [(η-C5H5)W-
(CO)3]Ϫ). This appears particularly attractive in heterometallic
chemistry where tuning of the selectivity of metal–metal and
metal–ligand interactions plays an essential role in syn-
formation of a covalent metal–metal bond. This was confirmed
thetic chemistry and has considerable structural and catalytic
by an X-ray diffraction study (see below). In the 1H NMR
spectrum, the resonances for the 3,4-borole protons show
shoulders owing to coupling with 199Hg (I = 1/2, 16.9% natural
abundance). A homodecoupling experiment of the 2,5-borole
protons did not allow a complete resolution of the signal and its
satellites and the value of the 3J(H–Hg) coupling constant was
estimated as 9 Hz.
consequences.1 Recent studies in our groups with the carbon-
ylmetalates [(η-C4H4BPh)Re(CO)3]Ϫ and [(η-C4H4BPh)Fe-
(CO)2H]Ϫ have established that these reagents are convenient
precursors to incorporate a borole ligand in heterobimetallic
2
3
systems. The resulting Re2Pd2 and FeAu2 complexes, shown
below, have demonstrated that the borole ligand is susceptible
to bind to a single metal centre in an η5 manner and in addition,
to an adjacent metal via a boron–metal interaction. Considering
the very limited number of heterometallic borole complexes
known at the moment,2–6 we sought to evaluate further the syn-
thetic potential of these reagents in heterometallic chemistry.
Reaction of [NMe4][Re] with an excess of HgCl2 in toluene
afforded colourless [Re]–Hg–Cl 2 [eqn. (2)].
1
The H NMR resonances of the 3,4-borole protons clearly
show the 199Hg satellites and decoupling of the 2,5-borole
protons led to a spectral resolution which allowed to determine
3J(H–Hg) = 22.3 Hz, a value significantly larger than for 1.
As expected, reaction of 2 with [NMe4][Re] led to 1 which,
in turn, reacts with HgCl2 to give 2. The corresponding
symmetrization equilibrium is slow on the 1H NMR time-scale
since it does not affect the resolution of the signals for each of
these complexes present in the reaction mixture [eqn. (3)].
Results and discussion
A. Reactions with [NMe4][(ꢀ-C4H4BPh)Re(CO)3] ([NMe4][Re])
The reaction of HgCl2 with an excess of this rhenium metalate
in toluene led to the light green trinuclear chain complex [Re]–
Hg–[Re] 1 which is soluble in this solvent, in contrast to the
precursors [eqn. (1)].
The shift of the ν(CO) absorptions towards higher wave-
numbers in 1 compared to [NMe4][Re] is consistent with the
† Part of the PhD Thesis of M. N.
‡ Dedicated to Dr Marcel Sergent (Université de Rennes I), on the
occasion of his retirement, with our warmest wishes.
J. Chem. Soc., Dalton Trans., 1999, 2807–2812
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Table 1 FIR Data for [Re]Ϫ, [Re]–HgCl 2, [Re]–Hg–[Re] 1 and related
complexes
ν/cmϪ1
[Re]
326w, 193w, 119w
362m, 286m
338w, 159m
169s, 115m
2
1
[W]–Hg-[W]7
HgCl2
374s
(C6Cl5)HgCl
357s, 330m, 119m
[W] = WCp(CO)3.
Table
2
Infrared ν(CO) absorptions for [Re]Ϫ10 and [Re]–MLn
(M = Hg, Cu, Ag, Au)
Complex
Medium
Absorptions/cmϪ1
[Re]Ϫ
[Re]–Hg–[Re] 1
CH2Cl2
Toluene
KBr
Toluene
KBr
1970s, 1867s, 1855 (sh)
2040s, 2020s, 1960 (sh), 1949s
2038w, 2017s, 1961s, 1947s
2050s, 1985 (sh), 1971s
2050s, 1975s, 1946s
in Table 2. A comparison of the average ν(CO) frequencies
[Re]–Hg–Cl 2
leads for the groups attached to [Re] to the following sequence
of decreasing frequencies: HgCl > [Re]–Hg > Au(PPh3) >
Ag(PPh3) ≈ Cu(PPh3)2 which could reflect a decreasing covalent
character for these complexes, although steric factors may
interfere with the electronic effect of the donor/acceptor
properties of the metal fragments. A similar sequence has been
established for related group 6 bimetallic complexes.11
[Re]–Cu(PPh3)2 3
[Re]–Ag(PPh3) 4
[Re]–Au(PPh3) 5
Toluene
Toluene
Toluene
1997s, 1919s, 1890s
1996s, 1919s, 1894s
2007s, 1935s, 1914s
In contrast, the equilibrium shown in eqn. (4) is significantly
faster and induces broadening of the borole H NMR reson-
1
ances in CH2Cl2 at room temperature.
The far-IR absorptions of 1 and 2 are compared in Table 1
with those of related molecules.
When the reaction between [NMe4][Re] and [AuCl(PPh3)]
was performed in CH2Cl2 instead of toluene, an equilibrium
was established between all the soluble reaction partners
[eqn. (9)] in which the ratio 5:[NMe4][Re] was ca. 2:1.
By comparison with the νasym(Hg–W) absorption at 169 cmϪ1
in [Hg{W(CO)3Cp}2]7 and with the value of 152 cmϪ1 for
the νasym(Au–W) vibration in the isoelectronic complex [Au-
{W(CO)3Cp}2]Ϫ,8 we assign the absorption at 159 cmϪ1 in 1
to the metal–metal vibration νasym(Hg–Re). In view of the simi-
larity between the atomic masses of W and Re, and between
their ligands, the difference of 10 cmϪ1 between the values for
νasym(Hg–W) and νasym(Hg–Re) appears indicative of a weaker
force constant for the metal–metal bond in 1.
The absorption at 362 cmϪ1 in 2 may be confidently assigned
to ν(Hg–Cl) by comparison with those we found at 374 and 357
cmϪ1 for [HgCl2] and [HgCl(C6Cl5)], respectively. An absorption
observed at 286 cmϪ1 could tentatively be due to dimer
formation in the solid-state, generating bridging chlorides, as
also observed with the related complex [Cp(OC)3Mo–HgCl]9
[eqn. (5)].
Whereas the IR absorptions of both [NMe4][Re] and 5 are
1
clearly present in the spectrum of the reaction mixture, the H
NMR resonances of the 2,5-borole protons are broad at room
temperature and indicate chemical exchange. Owing to the
smaller ∆ν separation between the individual signals of the 3,4-
borole protons of these complexes, they are already in the fast
exchange regime in the mixture at room temperature.
Crystal structure of [Re]–Hg–[Re] 1. A view is shown in
Fig. 1 and selected bond distances and angles are reported in
Table 3.
The mercury atom occupies an inversion centre in the
molecule and the Re–Hg distance of 2.748(1) Å compares with
the values found in the literature for this bond, which range
from 2.621 to 2.790 Å.13
This would also be consistent with the observation that the
ν(CO) absorptions of 2 appear at slightly lower wavenumbers in
KBr than in solution, whereas those of 1 remain unaffected
(Table 2).
Synthesis of Re–M complexes (M ؍ Cu, Ag, Au). The com-
plexes [Re]–Cu(PPh3)2 3, [Re]–Ag(PPh3) 4 and [Re]–Au(PPh3) 5
were prepared in benzene or toluene in which they are soluble,
in contrast to [NMe4][Re] and [NMe4]Cl [eqn. (6)–(8)]. Only 5
was isolated in the solid state while 3 and 4 were spectroscopi-
cally characterized in situ.
It is interesting to compare the structure of 1 with that of its
isoelectronic and isolobal analogue [Hg{W(CO)3Cp}] which
contains a C2-axis passing through the Hg atom.14 The W–Hg
distance of 2.7513(3) Å is similar to the Hg–Re distance in 1.
A comparison of the geometries around the Re and W centres
in these molecules is shown in Fig. 2.
The IR ν(CO) data for these colourless complexes are given
The borole ring approaches the Hg centre more than the Cp
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J. Chem. Soc., Dalton Trans., 1999, 2807–2812

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Fig. 2 Comparison of the structural arrangements in [Re]–Hg–[Re] 1
and in [W]–Hg–[W] (Hg–M–COtrans are always in the projection plane).
Fig. 1 Molecular structure of 1 in the crystal (PLATON12). Displace-
ment ellipsoids and spheres are drawn at 30% probability. Primed atoms
are related to unprimed ones by inversion.
Table 3 Selected interatomic distances (Å) and angles (Њ) for [Re]–Hg–
[Re] 1
Hg–Re
Re–C1
C1–O1
Re–C2
C2–O2
Re–C3
C3–O3
Re–B
2.748(1)
1.97(3)
1.12(3)
1.89(3)
1.18(3)
1.90(3)
1.16(2)
2.52(3)
2.29(2)
2.22(2)
B–C10
1.53(3)
1.44(3)
1.40(3)
1.37(3)
1.58(3)
1.58(3)
3.09(3)
2.20(2)
2.26(2)
C10–C11
C11–C12
C12–C13
C13–B
B–C14
Hg–B
Re–C12
Re–C13
Re–C10
Re–C11
Re–Hg–ReЈ
C1–Re–C2
C1–Re–C3
C2–Re–C3
Re–C1–O1
Re–C2–O2
Re–C3–O3
180.0
86(1)
108.0(9)
86(1)
174(2)
175(2)
174(2)
Hg–Re–B
71.8(6)
108(2)
108(2)
113(2)
107(2)
101(2)
B–C10–C11
C10–C11–C12
C11–C12–C13
C12–C13–B
C13–B–C10
ligand in the tungsten–mercury complex. It shows a 13Њ folding
along the C(13)–C(10) axis (the boron atom is situated 0.22 Å
out of the mean plane containing the four borole carbon atoms,
away from the Re). The fact that this deviation is not accom-
panied by an unusual slip distortion (this amounts to only 0.08
Å) indicates that it does not result from a tendency for the
borole ligand to change its coordination from η5 to η4 but
merely reflects the steric interactions between the phenyl groups
and the carbonyl ligands of the other rhenium unit. Finally, one
should note that the resulting B–Hg separation of 3.09(3) Å
is probably too long to represent a significant bonding
interaction. For comparison, a B–Pd distance of 2.59(2) Å has
been observed recently in the tetranuclear, centrosymmetric
cluster {[Re]Pd}2.2
Fe moiety are almost orthogonal to each other [95.2(4)Њ]. The
hydride ligands could be located by a difference Fourier
synthesis. They occupy a bridging position, resulting in a three
center–two electron (3c–2e) bonding for the Fe(µ-H)Pt unit.
The 4-Mepy ligand is almost perpendicular to the Pt(µ-H)Fe
plane.
Relevant distances in platinum bridging hydride complexes
are compared in Table 5. The range of Pt(µ-H) distances is large
(1.40–2.21 Å) and this is also reflected in the values found for
1J [Pt(µ-H)] coupling constants in 1H NMR spectroscopy
(Table 6). Complex 6 is isoelectronic with the Mn–Pt–Mn
complex trans-[{CpЈ(OC)2Mn(µ-H)}2Pt(3-Mepy)2]14 [(η-C4H4-
B. Reactions with [NBu4][(ꢀ-C4H4BPh)Fe(CO)2H] ([NBu4][Fe])
The reaction of two equivalents of [(η-C4H4BPh)Fe(CO)2H]Ϫ
([Fe]Ϫ) with trans-[PtBr2(4-Mepy)2] (4-Mepy = 4-methylpyr-
idine) led to the trinuclear complex trans-[Fe]–Pt(4-Mepy)2–[Fe]
6 [eqn. (10)].
In solution this complex (like its pyridine analogue prepared
similarly) is very air- and moisture-sensitive. The detailed
arrangement of the ligands, including the presence of bridging
hydrides, was ascertained by an X-ray diffraction study on dark
ruby-red single crystals obtained from CH2Cl2–toluene.
←→
BPh)Fe o CpЈMn]. In these complexes, the iron and man-
1
ganese centres have similar ligand arrangements. Both the H
NMR chemical shift for the µ-H ligand and the 1J(Pt–H) values
are very similar in these complexes. In the other complexes
which contain phosphine ligands, the coupling constants are
smaller.
Reaction of [NBu4][Fe] with cis-[PtCl2(PR3)]2. When [Fe]Ϫ
was reacted with cis-[PtCl2(PR3)2] in a manner similar to that
used to prepare 6, only trans-[Pt(H)Cl(PR3)2] was character-
ized. It is likely that the hydride transfer reaction that leads
to this product occurs via a bimetallic complex containing a
bridging hydride ligand [eqn. (11)].
Crystal structure of 6. A view of the molecule is shown in
Fig. 3 and selected bond distances and angles are given in
Table 4.
The Pt atom occupies a centre of inversion in the molecule
and the Pt–Fe distance of 2.774(3) Å is consistent with the
presence of metal–metal bonds.15 The two CO ligands on each
It is interesting that the reaction of [HCr(CO)5]Ϫ with
[PtCl2(dppm-P,P)] [dppm = bis(diphenylphosphino)methane]
J. Chem. Soc., Dalton Trans., 1999, 2807–2812
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Table 4 Selected bond distances (Å) and angles (Њ) for trans-[Fe]–
Pt(4-Mepy)2–[Fe] 6
Pt–Fe
Pt–H
Fe–H
Fe–C1
C1–O1
Fe–C2
C2–O2
Fe–B
Fe–C21
Fe–C22
2.774(3)
1.70(7)
1.63(9)
1.713(9)
1.17(1)
1.84(1)
1.18(1)
2.14(1)
2.08(2)
2.09(1)
B–C21
1.54(2)
1.37(2)
1.42(2)
1.42(2)
1.55(2)
1.58(1)
2.022(7)
2.050(9)
2.04(1)
C21–C22
C22–C23
C23–C24
C24–B
B–C31
Pt–N
Fe–C23
Fe–C24
Fe–Pt–H
H–Fe–Pt
Pt–H–Fe
Fe–Pt–N
H–Pt–N
Pt–N–C11
Pt–N–C15
Pt–Fe–C1
Pt–Fe–C2
C1–Fe–C2
Fe–C1–O1
33(3)
34(3)
113(5)
87.9(2)
86(3)
120.2(5)
122.7(7)
73.8(3)
96.0(3)
95.2(4)
178.4(9)
Pt–Fe–B
140.2(3)
110(1)
110(1)
110.2(9)
107.8(9)
101.4(8)
175.9(9)
B–C21–C22
C21–C22–C23
C22–C23–C24
C23–C24–B
C21–B–C24
Fe–C2–O2
Fig. 3 Molecular structure of 6 in the crystal (PLATON12). Displace-
ment ellipsoids and spheres are drawn at 30% probability. Primed atoms
are related to unprimed ones by inversion.
[Re]–Hg–[Re] 1 and [Re]–Hg–Cl 2. A suspension of
[NMe4][Re] (164 mg, 0.34 mmol) and HgCl2 (27 mg, 0.1 mmol)
in toluene (10 mL) was stirred for 2 h. The yellow–green solu-
tion was filtered, evaporated to dryness and the resulting solid
recrystallized from CH2Cl2–hexane, affording 1 as yellow–green
crystals. Yield: 63 mg (0.062 mmol, 36% based on [Re]Ϫ)
(Found: C, 30.39; H, 1.80. C26H18B2HgO6Re2 (M = 1021.06)
1
requires C, 30.58; H, 1.78%). NMR: H (300 MHz, CDCl3),
δ 7.59, 7.34 (m, 10 H, phenyl), 5.11 (m, 4 H, N = 6.3 Hz,
3JH–Hg = 9 Hz, 3,4-borole), 3.58 (m, 4 H, N = 6.3 Hz, 2,5-
borole); (500 MHz, CDCl3), δ 7.57, 7.31 (m, 10 H, phenyl), 5.09
(m, 4 H, N = 6.4 Hz, 3,4-borole), 3.56 (m, 4 H, N = 6.4 Hz,
2,5-borole); 13C-{1H} (126 MHz, CDCl3), δ 191.32 (s, 6 C, CO),
136.26 (s, 4 C, ortho-phenyl), 128.92 (s, 2 C, para-phenyl),
128.29 (s, 4 C, meta-phenyl), 85.36 (s, 4 C, 3,4-borole), 73.97 (br
s, 4 C, 2,5-borole). IR (toluene): 2040s, 2020s, 1960 (sh), 1949s
cmϪ1; (KBr): 2038w, 2017s, 1961s, 1947vs cmϪ1; far-IR (poly-
ethylene): 338w, 159m cmϪ1. Mass spectrum (SIMSϩ, NBA):
m/z 1023 (MHϩ, 6.5%), 411 ([Re]ϩ, 100%), 383 ([Re]ϩ Ϫ CO,
21%), 327 ([Re]ϩ Ϫ 3 CO, 5.5%).
also led to hydride transfer with the high yield formation of
[Pt2(µ-H)(H)2(µ-dppm)2]ϩ.26
Treatment of 1 (35 mg, 0.34 mmol) with a large excess of
HgCl2 (ca. 200 mg) and extraction with 5 × 10 mL toluene
afforded a solution which was taken to dryness. The residue was
recrystallized from CH2Cl2–hexane to give [Re]–Hg–Cl 2 as
colourless crystals. Yield: 62 mg (0.096 mmol, 28% based
on [Re]Ϫ) (Found: C, 24.37; H, 1.47. C13H9BClHgO3Re (M =
In conclusion, we have found that borole-containing
carbonylmetalates are suitable precursors for the synthesis of
heterometallic, metal–metal bonded complexes which provide
interesting opportunities for the study of the interactions of
a borole ligand with one or more metal centres.2,3 These com-
plexes allow useful comparisons between molecules prepared
from isolobal metalates.
1
646.27) requires C, 24.16; H, 1.40%). NMR: H (300 MHz,
CD2Cl2), δ 7.84, 7.42 (m, 5 H, phenyl), 5.50 (m, 2 H, N = 6.5 Hz,
3,4-borole), 4.07 (m, 2 H, N = 6.5 Hz, 2,5-borole); (300 MHz,
CDCl3), δ 7.77, 7.42 (m, 5 H, phenyl), 5.45 (m, 2 H, N = 6.3 Hz,
3JH–Hg = 22.3 Hz, 3,4-borole), 4.04 (m, 2 H, N = 6.4 Hz, 2,5-
borole); (500 MHz, CDCl3), δ 7.75, 7.40 (m, 5 H, phenyl), 5.44
(m, 2 H, N = 6.4 Hz, Hg satellites not resolved, 3,4-borole), 4.03
(m, 2 H, N = 6.7 Hz, 2,5-borole); 13C-{1H} (126 MHz, CDCl3),
δ 188.36, 187.69 (s, 3 C, CO), 135.29 (s, 2 C, ortho-phenyl),
131.28 (s, 1 C, para-phenyl), 129.05 (s, 2 C, meta-phenyl), 86.34
(s, 2 C, 3,4-borole), 71.92 (br s, 2 C, 2,5-borole). IR (toluene):
2050s, 1985 (sh), 1971s cmϪ1; (KBr): 2050s, 1975s, 1946s cmϪ1;
far IR (polyethylene) 362m, 286m cmϪ1. Mass spectrum (EI,
140 ЊC): m/z 646 (Mϩ, 3%), 446 (Mϩ Ϫ Hg, 3%), 411 (Mϩ Ϫ
HgCl, 100%), 383 (Mϩ Ϫ HgCl Ϫ CO, 48%), 362 (Mϩ Ϫ Hg Ϫ
3 CO, 52%), 327 (Mϩ Ϫ HgCl Ϫ 3 CO, 84%), 202 (Hgϩ, 30%).
Experimental
Reactions were performed under purified nitrogen, using
standard Schlenk-type techniques. Solvents were distilled under
nitrogen and traces of water removed by usual methods. Infra-
red spectra were recorded on FT-IR Perkin-Elmer 1720 X and
FT-IR Bruker IFS 66/113 spectrometers. NMR spectra were
recorded on Varian VXR 500 (1H, 500 MHz, relative to TMS,
13C, 125.70 MHz, relative to TMS, 31P, 202.33 MHz, relative to
H3PO4), Bruker SY 200 (1H, 200 MHz, relative to TMS), and
Bruker WP 80 SY (1H, 80 MHz, relative to TMS) spectro-
meters. Elemental analyses were performed by the Analytisches
Labor Pascher, Remagen (Germany).
Syntheses
[Re]–Cu(PPh3)2 3. A mixture of [NMe4][Re] (14 mg, 0.03
mmol) and [Cu(PPh3)2]NO3 (19 mg, 0.03 mmol) was stirred in
toluene-d8 (0.3 mL) for a few minutes. The filtered solution was
studied by NMR. Since the complex was not isolated, yields
The complexes [NBu4][(η-C4H4BPh)Fe(CO)2H] and [NMe4]-
[(η-C4H4BPh)Re(CO)3] were prepared as described in the
literature.6a,10
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J. Chem. Soc., Dalton Trans., 1999, 2807–2812

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Table 5 Interatomic distances (Å) in hydrido-bridged di- and tri-metallic complexesa
Complex
M
d(M–Pt)
d(M–H)
d(Pt–H)
Ref.
[Fe]–Pt(4-Mepy)2-[Fe] 6
Fe
Mn
Mn
Re
Pt
Pt
Pt
2.774(3)
2.804(3)
2.864(1)
2.8673(4)
2.711(1)
2.728(1)
2.716(1)
1.63(9)
1.69(15)
1.80(8)
1.70(7)
2.00(15)
1.64(8)
2.21(6)
1.691(2), 1.656(2)
1.71, 1.40
1.55(4)
This work
[{CpЈ(OC)2Mn(µ-H)}2Pt(3-Mepy)2]b
[(OC)4Mn(µ-H)(µ-PPh2)PtPh(PPh3)]
[Cp(ON)Re(µ-H)(µ-PPh2)Pt(PPh3)2]ϩ
[(dppe)Pt(µ-H)2PtH(dppe)]ϩ c (triclinic)d
[(dppe)Pt(µ-H)2PtH(dppe)]ϩ (monoclinic)
[(dppe)Pt(µ-H)(µ-CO)Pt(dppe)]ϩ
16
17
18
19
20
21
22
1.57(6)
1.860(2), 2.049(2)
2.05, 1.78
1.55(4)
e
H2Fe(CO)4
Fe
1.56(2)
a Structural determination by d neutron diffraction, e electron diffraction, all others by X-ray diffraction. b 3-Mepy = 3-methylpyridine, CpЈ = methyl-
cyclopentadienyl. c dppe = 1,2-Bis(diphenylphosphino)ethane.
Table 6 Chemical shift (ppm) and J(Pt–H) coupling constants (Hz) for bridging hydrides in M–Pt-complexes
Complex
δ(M–H)
JPtH
Solvent
Ref.
[Fe]–Pt(4-Mepy)2–[Fe] 6
Ϫ14.74
919
924.8
370
494
480
476
506
537
409
503
CD2Cl2
THF-d8
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
?
This work
[{CpЈ(OC)2Mn(µ-H)}2Pt(3-Mepy)2]
[(OC)4Mn(µ-H)(µ-PPh2)PtPh(PPh3)]
[(OC)4Mn(µ-PPh2)(µ-H)Pt(PPh3)2]ϩ
[Cp(OC)2W(µ-PPh2)(µ-H)Pt(PPh3)2]ϩ
[(OC)3Co(µ-PPh2)(µ-H)Pt(PPh3)2]ϩ
[Cp(ON)Re(µ-H)(µ-PCy2)Pt(PPh3)(CO)]ϩ
[(Et3P)2(Cl5C6)Pt(µ-H)(AuPEt3)]
[(OC)4Mn(µ-CO)(µ-H)Pt(PEt3)2]
[(dppe)Pt(µ-H)2PtH(dppe)]ϩ
Ϫ14.86
Ϫ12.6
Ϫ11.94
Ϫ9.43
Ϫ9.16
Ϫ5.00
Ϫ4.73
Ϫ3.80
Ϫ2.7
16
17
23
23
23
18
24
25
20
C6D6
CD2Cl2
1
1
have not been determined. NMR: H (300 MHz, toluene-d8),
δ 7.75, 7.51, 7.23 (m, 35 H, phenyl), 5.18 (m, 2 H, N = 6.0 Hz,
3,4-borole), 4.21 (m, 2 H, N = 6.2 Hz, 2,5-borole); 31P-{1H} (121
MHz, toluene-d8), δ 0.2 (br s, 2 P). IR: see Table 2.
2 H, JHPt = 919 Hz, hydride). IR (KBr): 1967s, 1914s cmϪ1.
FIR (polyethylene): 398w, 387m, 377w, 338w, 328m, 316w,
294m, 256w, 204m, 159m, 135m cmϪ1. Mass spectrum (FABϩ,
NBA): m/z 887 (Mϩ, 0.2%), 381 (Mϩ Ϫ 2[Fe], 25%), 288
(Mϩ Ϫ 2[Fe] Ϫ (4-Mepy), 21%).
[Re]–Ag(PPh3) 4. A mixture of [NMe4][Re] (15 mg, 0.03
mmol) and [Ag(PPh3)]NO3 (13 mg, 0.03 mmol) was stirred in
benzene-d6 (0.3 mL) for a few minutes. The filtered solution was
studied by NMR. Since the complex was not isolated, yields
have not been determined. NMR: 1H (300 MHz, benzene-
d6), δ 7.69 (m, 2 H, ortho-phenylborole), 7.17 (m, 6 H, ortho-
phenylphosphine), 6.97 (m, 9 H, meta- and para-phenylphosphine),
6.85 (m, 2 H, meta-phenylborole), 6.68 (m, 1 H, para-phenylborole),
4.90 (m, 2 H, N = 5.7 Hz, 3,4-borole), 4.11 (m, 2 H, N = 5.7 Hz,
2,5-borole); 31P-{1H} (121 MHz, benzene-d6), δ 15.8 (s, 1P,
∆ν1/2 = 70 Hz). IR: see Table 2.
Reaction of [NBu4][Fe] with cis-[PtCl2(PEt3)2]. A solution of
[NBu4][Fe] (94 mg, 0.19 mmol) in CH2Cl2 (2 mL) was cooled to
Ϫ78 ЊC and solid [PtCl2(PEt3)2] (48 mg, 0.10 mmol) was added.
After the mixture had reached room temperature, it was taken
to dryness and the solid was extracted with diethyl ether. This
solution was filtered and taken to dryness, affording a solid
1
identified by H and 31P-{1H} NMR spectroscopy and com-
parison with the literature data, as trans-[PtHCl(PEt3)2].27
Reaction of [NBu4][Fe] with cis-[PtCl2(PPh3)2]. To a solid
mixture of [NBu4][Fe] (126 mg, 0.25 mmol) and cis-
[PtCl2(PPh3)2] (101 mg, 0.13 mmol) cooled to Ϫ78 ЊC was
added precooled CH2Cl2 (5 mL). After the mixture had reached
room temperature, it was taken to dryness and the solid was
extracted with diethyl ether. This solution was filtered and
taken to dryness, affording an ochre solid (97 mg) which was
shown by 1H and 31P-{1H} NMR spectroscopy and comparison
with the literature data to contain mostly trans-[PtHCl-
(PPh3)2].28
[Re]–Au(PPh3) 5. A mixture of [NMe4][Re] (18 mg, 0.04
mmol) and [AuCl(PPh3)] (18 mg, 0.04 mmol) was stirred in
toluene-d8 (0.3 mL) for a few minutes. The filtered solution was
studied by NMR. Complex 5 was obtained from toluene–
hexane as small, white cystals. Yield: 28 mg (82%) (Found: C,
42.57; H, 2.58. C31H24AuBO3PRe (M = 869.49) requires C,
1
42.82; H, 2.78%). NMR: H (300 MHz, toluene-d8), δ 7.90,
7.39, 7.17, 7.06 (m, 20 H, phenyl), 5.01 (m, 2 H, N = 6.2 Hz,
3,4-borole), 4.20 (m, 2 H, N = 6.3 Hz, 2,5-borole); 31P-{1H} (121
MHz, toluene-d8), δ 50.6 (s, 1 P). IR: see Table 2.
X-Ray crystallography
trans-[Fe]–Pt(4-Mepy)2–[Fe] 6. Solid [PtBr2(4-Mepy)2] (167
mg, 0.31 mmol) was added to a solution of [NBu4][Fe] (306 mg,
0.62 mmol) at Ϫ78 ЊC in CH2Cl2 (5 mL). After the stirred
reaction mixture had reached room temperature, it was filtered
through silica gel. Crystallization from CH2Cl2–toluene at
Ϫ25 ЊC afforded 6 (73 mg, 0.08 mmol, 27%) as ruby-red crys-
tals. Slow decomposition of the sample, also observed during
crystallization, prevented correct elemental analysis (Found:
C, 47.03; H, 3.87; N, 3.32. C36H34B2Fe2N2O4Pt (M = 887.09)
Crystal data for complex 1. C26H18B2HgO6Re2; M = 1021.1;
a = 10.911(4), b = 8.467(3), c = 15.374(6) Å, β = 110.13(3)Њ,
V = 1333.6(9) Å3, T = 253 K, monoclinic space group P21/n
(no. 14), Z = 2, Dc = 2.543 g cmϪ3, Mo-Kα radiation (λ = 0.71073
Å); graphite monochromator, µlin = 15.0 mmϪ1. ENRAF-
Nonius CAD4 diffractometer; green translucent crystal frag-
ment of size 0.25 × 0.25 × 0.20 mm, ω scans with 3 < θ < 23Њ in
the index range 0 < h < 16, 0 < k < 6, Ϫ16 < l < 15; 1532 reflec-
tions. Correction for Lorentz and polarization effects and
empirical absorption correction (min. transmission 0.090, max.
transmission 0.107) based on azimuthal scans.29 1191 unique
(Rint = 0.068) observations with I > 1.0σ(I) for structure
solution30 by Patterson and subsequent Fourier difference
syntheses. Least-squares refinement on F30 with anisotropic
1
requires C, 48.74; H, 3.86; N, 3.16%). H NMR (200 MHz,
3
CD2Cl2), δ 8.4 (d, 4 H, JHH = 6 Hz, 2,6-H from 4-Mepy), 7.4
(m, 4 H, phenyl), 7.15 (m, 6 H, phenyl), 7.1 (d, 4 H, 3JHH = 6 Hz,
3,5-H from 4-Mepy), 4.66 (m, 4 H, 3,4-borole), 4.42 (s, 6 H,
CH3), 2.57 (m, 4 H, 2,5-borole), Ϫ14.74 (s with Pt-satellites,
J. Chem. Soc., Dalton Trans., 1999, 2807–2812
2811

View Article Online
3 P. Braunstein, G. E. Herberich, M. Neuschütz, M. U. Schmidt,
U. Englert, P. Lecante and A. Mosset, Organometallics, 1998, 17,
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6 (a) G. E. Herberich, T. Carstensen, N. Klaff and M. Neuschütz,
Chem. Ber., 1992, 125, 1801; (b) see also, P. Braunstein, G. E.
Herberich, M. Neuschütz and M. U. Schmidt, J. Organomet. Chem.,
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7 P. N. Brier, A. A. Chalmers, J. Lewis and S. B. Wild, J. Chem. Soc. A,
1967, 1889.
displacement parameters for the metal and oxygen atoms,
isotropic displacement parameters for the remaining non-
hydrogen atoms, hydrogen atoms in calculated positions
(C–H = 0.98 Å). Convergence (maximum ∆/σ = 0.005) for 100
variables and 1191 observed data at R = 0.059, Rw = 0.059
(wϪ1 = σ2Fo). A final difference Fourier map showed a local
maximum of 1.6 e ÅϪ3 close to the Hg atom.
Crystal data for complex 6. C36H34B2Fe2N2O4Pt; M = 887.09;
a = 8.532(2), b = 10.445(3), c = 10.430(3) Å, α = 100.75(2),
β = 101.13(2), γ = 101.15(2)Њ, V = 870.3(4) Å3, T = 248 K, tri-
Ϫ3
¯
clinic space group P1 (no. 2), Z = 1, Dc = 1.69 g cm , Mo-Kα
8 P. Braunstein, U. Schubert and M. Burgard, Inorg. Chem., 1984, 23,
4057.
radiation (λ = 0.71073 Å); graphite monochromator, µlin = 4.91
mmϪ1. ENRAF-Nonius CAD4 diffractometer; red parallel-
epipedic crystal of size 0.15 × 0.15 × 0.15 mm, ω scans with
3 < θ < 27Њ in the index range Ϫ10 < h < 10, Ϫ13 < k < 13,
0 < l < 12, 3248 reflections. Correction for Lorentz and polar-
ization effects and empirical absorption correction (min. trans-
mission 0.770, max. transmission 0.992) based on azimuthal
scans.29 2477 unique (Rint = 0.018) reflections for structure
solution with the Patterson method. Both unit cell metric and
symmetry of the diffraction pattern are in close agreement with
a monoclinic symmetry which, however, would require exten-
sive disorder and partial occupancy for most atoms. Refinement
of the disordered structure model gives satisfactory agreement
factors but results in unreasonably short intermolecular
contacts. We hence prefer to describe the crystal as a pseudo-
merohedral twin. For completion of the structure model and
the twin refinement the SHELXL 93 program was used.31
Least-squares refinement on intensities with anisotropic dis-
placement parameters for all non-hydrogen atoms, isotropic
displacement parameter for the hydrido H atom, remaining
hydrogen atoms in calculated positions (C–H = 0.98 Å).
Convergence (maximum ∆/σ = 0.004) was obtained for 220
9 M. J. Albright, M. D. Glick and J. P. Oliver, J. Organomet. Chem.,
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10 G. E. Herberich, B. J. Dunne and B. Heßner, Angew. Chem. 1989, 101,
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11 L. M. Bower and M. H. B. Stiddard, J. Chem. Soc. A, 1968, 706.
12 A. L. Spek, PLATON-94, University of Utrecht, The Netherlands,
1994.
13 N. E. Kolobova, Z. P. Valueva, E. I. Kazimirchuk, V. G. Adrianov
and Yu. T. Struchkov, Isv. Akad. Nauk SSSR, Ser. Khim., 1984, 920;
D. S. Williams, J. T. Anhaus, M. H. Schofied, R. R. Schrock and
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U. Flörke, H.-J. Haupt and R. Siefert, Z. Kristallogr., 1996, 211, 695.
14 L.-C. Song, H. Yang, Q. Dong and Q.-M. Hu, J. Organomet. Chem.,
1991, 414, 137.
15 P. Braunstein, J.-L. Richert and Y. Dusausoy, J. Chem. Soc., Dalton
Trans., 1990, 3801.
16 E. Kunz, M. Knorr, J. Willnecker and U. Schubert, New J. Chem.,
1988, 12, 467.
17 J. Powell, J. F. Sawyer and M. Shiralian, Organometallics, 1989, 8,
577.
18 J. Powell, J. F. Sawyer and M. V. R. Stainer, J. Chem. Soc., Chem.
Commun., 1985, 1314.
19 M. Y. Chiang, R. Bau, G. Minghetti, A. L. Bandini, G. Banditelli
and T. F. Koetzle, Inorg. Chem., 1984, 23, 122.
20 C. B. Knobler, H. D. Kaesz, G. Minghetti, A. L. Bandini,
G. Banditelli and F. Bonati, Inorg. Chem., 1983, 22, 2324.
21 G. Minghetti, A. L. Bandini, G. Banditelli, F. Bonati, R. Szostak,
C. E. Strouse, C. B. Knobler and H. D. Kaesz, Inorg. Chem., 1983,
22, 2332.
22 E. A. McNeill and F. R. Scholer, J. Am. Chem. Soc., 1977, 99, 6243.
23 P. Braunstein, E. de Jesús, A. Tiripicchio and F. Ugozzoli, Inorg.
Chem., 1992, 31, 411.
24 H. Lehner, D. Matt, P. S. Pregosin, L. M. Venanzi and A. Albinati,
J. Am. Chem. Soc., 1982, 104, 6825.
variables and 2477 data at R = 0.030, wR2 = 0.089 {wϪ1
=
2
2
σ2(Fo ) ϩ [0.0667(max(Fo ,0) ϩ 2Fc2)/3]2}. A final difference
Fourier map showed fluctuations <1.1 e ÅϪ3 close (0.7 Å) to Pt.
CCDC reference number 186/1534.
See http//www.rsc.org/suppdata/dt/1999/2807/ for crystallo-
graphic files in .cif format.
Acknowledgements
We are grateful to the DAAD for a grant to M. N. and the
Centre National de la Recherche Scientifique (Paris) for finan-
cial support.
25 O. Bars, P. Braunstein, G. L. Geoffroy and B. Metz,
Organometallics, 1986, 5, 2021.
26 P. Braunstein and B. Oswald, J. Organomet. Chem., 1987, 328, 229.
27 G. W. Parshall, Inorg. Synth., 1970, 12, 28.
28 I. Collamati, A. Furlani and G. Attioli, J. Chem. Soc. A, 1970, 1694;
C. Eaborn, A. Pidcock and B. R. Steele, J. Chem. Soc., Dalton
Trans., 1976, 767.
29 A. C. T. North, D. C. Phillips and F. S. Mathews, Acta Crystallogr.,
Sect. A, 1968, 24, 351.
30 ENRAF-Nonius, SDP Version 5.0, 1989, Delft, 1989.
31 G. M. Sheldrick, SHELXL 93, Program for Structure Refinement,
University of Göttingen, 1993.
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Paper 9/03846I
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J. Chem. Soc., Dalton Trans., 1999, 2807–2812