Synthesis and structure of a cationic platinum borylene complex

Article abstract of DOI:10.1002/anie.200605191

Making a B line: The boryl complex trans-[(Cy₃P) ₂Pt(Br){B(Mes)Br}] was synthesized and converted into the first two-coordinate borylene complex of platinum, trans-[(Cy₃P) ₂Pt(Br)(BMes)]⁺ (see picture), in which the boron atom is linearly coordinated. The bonding situation was analyzed by theoretical calculations and structural methods. Mes = 2,4,6-Me₃C ₆H₂. (Chemical Equation Presented).

Full text of DOI:10.1002/anie.200605191

Angewandte
Chemie
DOI: 10.1002/anie.200605191
Boron Ligands
Synthesis and Structure of a Cationic Platinum Borylene Complex**
Holger Braunschweig,* Krzysztof Radacki, and Katharina Uttinger
Terminal borylene complexes with two-coordinate boron
atoms were first reported in 1998[1] and have since attracted
significant interest owing to their close relationship to
ubiquitous carbonyl complexes[2] and,moreover,because of
their propensity to serve as unique sources for elusive
over,Pt and to a somewhat lesser extent Pd have proven to
form transition-metal complexes with boron-centered ligands
in far more unusual coordination modes,including metal
base-stabilized boryl[11] and borylene species[3c,12] or hetero-
dinuclear borylene complexes.[13] Herein we report on the first
platinum borylene species with a two-coordinate boron center
À
borylene units (B R) under ambient conditions. The latter
À
has allowed for the versatile and synthetically very useful
borylene transfer to various transition-metal fragments[3] or
even to unsaturated organic substrates.[4] To date,the range of
neutral terminal borylene complexes is limited to the early
transition metals V,[3b] Cr,[3a,5] and W.[1] Furthermore,a few
cationic species have been reported exclusively for Fe.[4b,6]
Corresponding terminal borylene complexes of the late
transition metals,however,have not been realized as of yet,
with the exception of the base-stabilized platinum species 1
(Scheme 1). Although this compound can be considered in a
and pronounced Pt B-multiple-bond character.
Recently,we described the formation of
trans-
[(Cy3P)2Pt(Br){B(Fc)Br}] (Fc = ferrocenyl) upon oxidative
addition of [FcBBr2] to [Pt(PCy3)2],[14] and its conversion to
the unprecedented T-shaped three-coordinate platinum boryl
complex trans-[(Cy3P)2Pt{B(Fc)Br}][BArF ] (3),which was
4
obtained by selective bromide abstraction from the Pt center.
Subsequently, 3 was converted to 1 by addition of 4-
methylpyridine to the boron atom with concomitant formal
migration of bromide from the B to Pt atom.[7] Similarly,we
have now obtained the boryl complex trans-[(Cy3P)2Pt(Br){B-
(Mes)Br}] (4) by mixing equimolar amounts of [Pt(PCy3)2]
and MesBBr2 in benzene (Scheme 2). Instantaneously,a
Scheme 1. Molecular structure of the base-stabilized borylene com-
plexes 1 and 2 and the T-shaped boryl complex 3, the precursor of 1;
Cy =cyclohexyl, ArF =3,5-(CF3)2C6H3.
very formal sense as the 4-methylpyridine adduct of a
borylene complex,the boron center displays predominantly
boryl character owing to its increased coordination number.[7]
A very similar finding was made for the base-stabilized
compound 2 and related osmium complexes,which display
Scheme 2. Synthesis of 4 and 5ab. a) C6H6; b) Na[BArF ] or K[B(C6F5)4]
in CD2Cl2.
4
À
Os B bond lengths more characteristic for osmium boryl
[8]
À
complexes [LxOs BR2].
À
While complexes with significant Pt B multiple-bond
character have so far remained unknown,the chemistry of
platinum–boron compounds is otherwise very well-estab-
white solid is formed and the precipitation of the product is
completed upon addition of hexane. Multinuclear NMR data
of the isolated solid (88% yield) are consistent with the
formulation of 4. The 11B{1H} NMR spectrum features a
broad signal at d = 68.7 ppm,which is slightly downfield-
shifted with respect to that of the starting borane (d =
61.7 ppm).[15] In the 31P{1H} NMR spectrum a singlet at d =
18.9 ppm (1JP-Pt = 3054 Hz) is observed,which is strongly
upfield-shifted in comparison to that of [Pt(PCy3)2] (d =
lished. In particular,platinum boryl complexes of the type
[9]
À
[LxPt BR2] are numerous and thoroughly investigated,
mostly owing to their importance as key intermediates for
the metal-mediated diboration of organic substrates.[10] More-
61.9 ppm, JP-Pt = 4120 Hz).[16] The presence of the mesityl-
[*] Prof. H. Braunschweig, Dr. K. Radacki, K. Uttinger
Institut für Anorganische Chemie
1
1
bromoboryl group is confirmed by the H NMR spectrum,
Julius-Maximilians-Universität Würzburg
AmHubland, 97074 Würzburg (Germany)
Fax: (+49)931-888-4623
which shows a broad resonance for the aryl protons at d =
6.83 ppm in CD2Cl2 (two respective signals are found in
benzene),two for the methyl groups in ortho position at d =
3.61 and 2.79 ppm,and one sharp signal for the methyl
substituent in para position at d = 2.18 ppm. The presence of
two chemically nonequivalent ortho-methyl groups indicates
E-mail: h.braunschweig@mail.uni-wuerzburg.de
[**] This work was supported by the DFG.
Supporting information for this article is available on the WWW
under http://www.angewandte.org or fromthe author.
Angew. Chem. Int. Ed. 2007, 46, 3979 –3982
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3979

Communications
À
hindered rotation around the B Cipso bond,which is further
substantiated by variable-temperature 1H NMR spectroscopy
in deuterated toluene. At À108C the corresponding signals
are sharper (d = 6.89 and 6.78 ppm for the two aryl protons,
d = 4.00 and 3.05 ppm for the ortho-methyl groups),while
heating to 1008C leads to coalescence of the two nonequiva-
lent aryl proton resonances (d = 6.81 ppm) and methyl groups
(d = 3.38 ppm),respectively.
K[B(C6F5)4] as the halide-abstraction reagent. Multinuclear
NMR data show the same set of signals in the 31P{1H} NMR
and 1H NMR spectra,while the 11B{1H} NMR spectrum
displays a singlet at d = À17.62 ppm for the [B(C6F5)4]À ion.
A single crystal,isolated by layering the reaction mixture with
hexane and cooling to À358C,could be analyzed by X-ray
diffraction,proving the constitution of the product as the first
terminal platinum borylene complex trans-[(Cy3P)2Pt(Br)-
(BMes)][B(C6F5)4] (5b; see Scheme 2).[17]
A single crystal suitable for an X-ray diffraction study
could be obtained from a solution of 4 in benzene by slow
evaporation of the solvent. The molecular structure and
relevant bond lengths and angles are displayed in Figure 1.[17]
The complex crystallizes in the space group P21/n. The
boron atom is two-coordinate and linearly bound to its
neighboring atoms Pt and C (Pt1-B1-C1 178.15(9)8; Figure 2).
Figure 1. Molecular structure of 4; thermal ellipsoids are set at 50%
probability. Selected bond lengths [Š] and angles [8]: Pt1-B1 2.009(4),
Pt1-Br1 2.6246(4), B1-Br2 2.006(4), B1-C1 1.587(5); Pt1-B1-C1
132.2(3).
Figure 2. Molecular structure of 5b; thermal ellipsoids are set at 50%
probability. Hydrogen atoms as well as the [B(C6F5)4]À ion and
cocrystallized CH2Cl2 are omitted for clarity. Selected bond lengths [Š]
and angles [8]: Pt1-B1 1.859(3), Pt1-Br1 2.5418(6), B1-C1 1.495(4); Pt1-
B1-C1 178.15(9).
À
The Pt Br bond length (2.6246(4) Š) is comparable to that of
trans-[(Cy3P)2Pt(Br){B(Fc)Br}] (2.6183(8) Š),but longer
than that in trans-[(Cy3P)2PtBr2] (2.435(1) Š).[18] The Pt B
À
À
À
bond length (Pt1 B1 2.009(4) Š) is very similar to that in
The Pt B bond (1.859(3) Š) is significantly shorter when
trans-[(Cy3P)2Pt(Br){B(Fc)Br}] (1.9963(34) Š)[14] or trans-
[(Ph3P)2Pt(Cl)(BCat)] (2.008(8) Š; Cat = catecholato).[19]
The boryl group is oriented orthogonally to the {PtP2}
fragment (C1-B1-Pt1-P1 90.6(4)8). Compound 4 is very air-
and moisture-sensitive,and shows slow decomposition in
solution,but can be stored as a solid under argon.
compared to the boryl complex 4 (2.009(4) Š),and to the
base-stabilized
species
1
(2.014(5) Š)[7]
or
[(h5-
3
À
C5Me5)(CO)Fe(m-CO)Pt(PCy3)(m-Br)Pt(PCy3)Br(m -B)] (B
Pt2 1.938(4) Š; B Pt1 2.158(4) Š),[3c] which all display three-
À
coordinate boron centers. This bond is also about 10 pm
shorter than that in the iminoboryl complex trans-
À ꢀ À
Treatment of trans-[(Cy3P)2Pt(Br){B(Mes)Br}] with Na-
[(Cy3P)2(Br)Pt B N SiMe3] (1.960(3) Š),which shows an
[BArF ] in CD2Cl2 afforded precipitation of a white powder
unusual boron atom that is only two-coordinate,however
electronically saturated by an effective BN triple bond,and
hence,of boryl character. [21] These findings are consistent with
4
(NaBr). The 31P{1H} NMR spectra of the reaction mixture
shows
a
new singlet at d = 45.0 ppm (1JP-Pt = 2072 Hz),
À
strongly downfield-shifted with respect to the corresponding
boryl complex. The 1H NMR spectra features only one sharp
signal for the two aryl protons (d = 7.01 ppm) and the ortho-
methyl groups (d = 2.72 ppm) of the mesityl fragment (d =
2.34 ppm for the para-methyl group). In the 11B{1H} NMR
the significant multiple-bond character of the B Pt linkage in
trans-[(Cy3P)2Pt(Br)(BMes)]+. Further electronic stabiliza-
tion of the coordinatively unsaturated boron atom in 5 could
be provided by interaction with the mesityl group as indicated
À
by a B Cipso bond (1.495(4) Š) that is significantly shorter
than that in the boryl complex 4 (1.587(5) Š). A similar
spectra only the resonance for the [BArF ]À ion can be
4
detected at d = À7.55 ppm,probably owing to unresolved
observation was made for a related cationic iron borylene
5
+
coupling to the platinum and phosphorus nuclei.[20]
complex [(h -C5Me5)Fe(CO)2(BMes)] (B Cipso 1.491(10) Š),
in comparison with its boryl precursor
[(h5-
C5Me5)Fe(CO)2{B(Br)Mes}] (B Cipso 1.569(3) Š).[6a] The
À
Attempts to grow suitable crystals for X-ray diffraction
analysis failed,and thus,we repeated the reaction with
À
3980 www.angewandte.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2007, 46, 3979 –3982

Angewandte
Chemie
À
Pt Br bond length (2.5418(6) Š) in 5b is comparable to the
Experimental Section
[21]
À ꢀ À
one in trans-[(Cy3P)2(Br)Pt B N SiMe3] (2.5516(4) Š),
4: Br2BMes (0.038 g,0.132 mmol) was dissolved in C 6H6 (1.0 mL) and
added to solid [Pt(PCy3)2] (0.100 g,0.132 mmol). The pale yellow
solution was layered with hexane (1.0 mL) and immediately a white
solid precipitated. The solid was allowed to settle and was separated
and washed with hexanes. After drying,122 mg of 4 was isolated
(88%). Crystals suitable for an X-ray diffraction study were obtained
but shorter with respect to the boryl complex
(2.6246(4) Š),thus indicating a weaker trans influence of
the borylene and iminoboryl ligands,respectively.
4
[22]
To gain deeper insight in the bonding situation of 5,Kohn–
Sham orbitals were examined,[23] resulting in two orbitals with
by recrystallization from a mixture of C6H6 and hexane by slow
evaporation of the solvent. H NMR (500 MHz,CD Cl2,24 8C): d =
À
considerable Pt B s-bonding character. Figure 3 shows the
1
2
6.83 (2 overlapping brs,2H,CH),3.61 (brs,3H,
o-CH3,Mes),2.79
(brs,3H, o-CH3,Mes),2.30–2.05 (m,6H,Cy),2.18 (s,3H,
p-CH3,
Mes),1.90–1.55 (m,36H,Cy),1.25–1.00 ppm (m,18H,Cy);
13C{1H} NMR (126 MHz,CD 2Cl2, 258C): d = 140.7 (s, o-C,Mes,
from 2D-HMBC),131.5 (s, m-C,Mes,from 2D-HMQC),130.7 (s, o-C,
Mes,from 2D-HMBC),129.8 (s, m-C,Mes,from 2D-HMQC),128.2
(s, i-C,Mes,from 2D-HMQC),35.7 (vt,C 1,Cy, N = 26 Hz),31.0–29.8
(3 overlapping s,2 o-CH3,Mes and C 3,5,Cy,from 2D-HMQC),27.8
(br s,C 2,6,Cy),26.8 (s,C 4,Cy),21.0 ppm (s, p-CH3,Mes) (because of
the poor solubility of the compound not all signals of the Mes group
could be detected); 11B{1H} NMR (160 MHz,CD 2Cl2,24 8C): d =
68.7 ppm (brs); 31P{1H} NMR (202 MHz,CD 2Cl2, 248C): d =
18.9 ppm (s, 1JP-Pt = 3054 Hz). Elemental analysis (%) calcd for
C45H77BBr2P2Pt·C6H6: C 54.50,H 7.44; found: C 54.38,H 7.07.
F
5a: Compound 4 (0.024 g,0.023 mmol) and Na[BAr 4] (0.020 g,
0.023 mmol) were put in a J. Young NMR tube and dissolved in
CD2Cl2 (0.6 mL). The reaction mixture turned slightly yellow after
5 min,and some fine powder precipitate (NaBr) was observed.
Multinuclear NMR spectra showed complete conversion of the
starting material and formation of 5a. After filtering over glass-fiber
filter paper the solution was layered with hexane (1.0 mL) and stored
À
Figure 3. Kohn–Shamorbitals of s and p components of the Pt B
bond in trans-[(Me3P)2Pt(Br)(BXyl)]+ (Xyl=xylyl); H white, Br orange,
at À358C. After one week pale yellow crystals precipitated (0.030 g,
1
B pink, C blue, P green, Pt brown.
71%). H NMR (500 MHz,CD Cl2,21 8C): d = 7.73 (m,8H, o-CH,
2
BArF ),7.57 (brs,4H, p-CH,BAr F4),7.01 (m,2H,CH,Mes),2.75 (m,
4
6H,Cy),2.72 (s,6H, o-CH3,Mes),2.34 (s,3H, p-CH3,Mes),2.06–1.99
pz orbital of the boron atom and the (dz2 + dx2Ày2) hybrid of the
platinum atom. Additionally,two orbitals (HOMO À8 and
HOMOÀ16) were identified,which characterize both orthog-
(m,12H,Cy),1.79–1.60 (m,30H,Cy),1.12–1.00 ppm (m,18H,Cy);
F
13C{1H} NMR (126 MHz,CD 2Cl2,21 8C): d = 162.0 (q, i-C,BAr
,
4
1JC-B = 50 Hz),150.9 (s, p-C,Mes),146.9 (s, o-C,Mes),135.1 (s, o-C,
BArF ),130.0 (s, m-C,Mes),129.2 (q, m-C,BAr F4, 2JC-F = 31 Hz),124.9
À
onal p components of the Pt B bond. These molecular
4
F
1
F
3
orbitals consist of B(px) and Pt(dxz) as well as B(py) and
Pt(dyz) atomic orbitals,respectively.
(q,CF ,BAr 4, JC-F = 272 Hz),117.7 (sep, p-C,BAr 4, JC-F = 4 Hz),
3
37.4 (vt,C ,Cy, N = 29 Hz),30.4 (s,C 3,5,Cy),27.3 (vt,C 2,6,Cy, N =
1
12 Hz),26.0 (s,C 4,Cy),23.1 (s, o-CH3,Mes),22.4 ppm (s, p-CH3,
Mes); 11B{1H} NMR (160 MHz,CD 2Cl2,21 8C): d = À7.6 ppm (s,
In contrast to [(h5-C5Me5)Fe(CO)2(BMes)]+ neither the
py orbital of the boron atom nor the dyz orbital of the platinum
atom plays a pronounced role in the in-phase p-type
BArF ); 31P{1H} NMR (202 MHz,CD 2Cl2,21 8C): d = 45.0 ppm (s,
4
1JP-Pt = 2072 Hz).
Elemental
analyses
(%)
calcd
for
interaction with the aromatic ring.[6a] Hence,the short B
À
C77H89B2BrF24P2Pt: C 50.56,H 4.90; found: C 50.81,H 4.85.
C
ipso distance of 5b when compared to that of 4 could merely
5b: Compound 4 (0.035 g,0.033 mmol) and K[B(C 6F5)4] (0.024 g,
0.033 mmol) were put in a J. Young NMR tube and dissolved in
CD2Cl2 (0.6 mL). The reaction mixture turned slightly yellow after
5 min,and some fine powder precipitate (KBr) was observed.
Multinuclear NMR spectra showed complete conversion of the
starting material and formation of 5b. After filtering over glass-fiber
filter paper the solution was layered with hexane (1.0 mL) and stored
at À358C. After one week pale yellow crystals precipitated (0.035 g,
64%). 1H NMR (500 MHz,CD 2Cl2,23 8C): d = 7.02 (m,2H,CH,
Mes),2.76 (m,6H,Cy),2.72 (s,6H, o-CH3,Mes),2.36 (s,3H, p-CH3,
Mes),2.06–1.99 (m,12H,Cy),1.79–1.60 (m,30H,Cy),1.12–1.00 ppm
be an effect of the decreased coordination number and the
positive charge at the boron center.
Computations on the cationic mesityl-, ortho,ortho-xylyl-,
ortho-tolyl-,and phenyl-substituted platinum arylborylene
and T-shaped aryl(bromo)boryl analogues of 3 revealed that
only the former two cations are thermodynamically more
stable in their borylene form (13.9 and 10.3 kJmolÀ1),thus
suggesting that for the stability of 5,both steric and electronic
effects are responsible.
In summary,the first base-free platinum borylene com-
plex was obtained from a trans-bromoboryl(bromo)platinum
precursor. Interestingly,its formation occurred by selective
bromide abstraction from the boron atom,thus in sharp
contrast to the earlier observed synthesis of cationic platinum
boryl complexes by bromide abstraction from the metal
center. Computations underline the decisive role of the
boron-bound substituent in these interesting transformations.
(m,18H,Cy); 13C{1H} NMR (126 MHz,CD Cl2,22 8C): d = 150.9 (s,
2
p-C,Mes),148.4 (d, p-C,[B(C 6F5)4], 1JC-F = 244 Hz),146.9 (s, o-C,
Mes),138.5 (d, o/m-C,[B(C 6F5)4], 1JC-F = 244 Hz),136.6 (d, o/m-C,
[B(C6F5)4], 1JC-F = 244 Hz),130.0 (s, m-C,Mes),124.9 (brs,
[B(C6F5)4]),37.4 (vt,C 1,Cy, N = 29 Hz),30.4 (s,C 3,5,Cy),27.3 (vt,C
i-C,
2,6
,
Cy, N = 12 Hz),26.0 (s,C 4,Cy),23.0 (s, o-CH3,Mes),22.5 ppm (s, p-
CH3,Mes); 11B{1H} NMR (160 MHz,CD Cl2,22 8C): d = À17.6 ppm
2
(s,[B(C 6F5)4]); 31P{1H} NMR (202 MHz,CD 2Cl2,22 8C): d = 45.0 ppm
Angew. Chem. Int. Ed. 2007, 46, 3979 –3982
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3981

Communications
(s, 1JP-Pt = 2073 Hz). Elemental analyses (%) calcd for
C69H77B2BrF20P2Pt·CH2Cl2: C 48.60,H 4.60; found: C 48.54,H 4.68.
[10] a) T. B. Marder,N. C. Norman, Top. Catal. 1998, 5,63 – 73; b) T.
Ishiyama,N. Matsuda,N. Miyaura,A. Suzuki, J. Am. Chem. Soc.
1993, 115,11018 – 11019.
[11] H. Braunschweig,K. Radacki,D. Rais,G. R. Whitell,
Angew.
Received: December 22,2006
Published online: April 12,2007
Chem. 2005, 117,1217 – 1219; Angew. Chem. Int. Ed. 2005, 44,
1192 – 1194.
[12] a) H. Braunschweig,D. Rais,K. Uttinger, Angew. Chem. 2005,
117,3829 – 3832; Angew. Chem. Int. Ed. 2005, 44,3763 – 3766;
b) H. Braunschweig,K. Radacki,D. Rais,K. Uttinger, Organo-
metallics 2006, 25,5159 – 5164; c) H. Braunschweig,C. Burschka,
M. Burzler,S. Metz,K. Radacki, Angew. Chem. 2006, 118,4458 –
4461; Angew. Chem. Int. Ed. 2006, 45,4352 – 4355.
[13] H. Braunschweig,K. Radacki,D. Rais,F. Seeler,K. Uttinger, J.
Am. Chem. Soc. 2005, 127,1386 – 1387.
[14] H. Braunschweig,K. Radacki,D. Rais,F. Seeler, Organometal-
lics 2004, 23,5545 – 5549.
Keywords: boron · borylene ligands · platinum·
structure elucidation · transition-metal complexes
.
[1] H. Braunschweig,C. Kollann,U. Englert, Angew. Chem. 1998,
110,3355 – 3357; Angew. Chem. Int. Ed. 1998, 37,3179 – 3180.
[2] a) H. Braunschweig, Angew. Chem. 1998, 110,1882 – 1898;
Angew. Chem. Int. Ed. 1998, 37,1786 – 1801; b) H. Braunsch-
weig,M. Colling, Coord. Chem. Rev. 2001, 223,1 – 51; c) H.
Braunschweig,M. Colling, Eur. J. Inorg. Chem. 2003,393 – 403;
d) H. Braunschweig, Adv. Organomet. Chem. 2004, 51,163 – 192;
e) H. Braunschweig,C. Kollann,D. Rais, Angew. Chem. 2006,
118,5380 – 5400; Angew. Chem. Int. Ed. 2006, 45,5254 – 5274;
f) J. Uddin,C. Boehme,G. Frenking, Organometallics 2000, 19,
571 – 582; g) J. Uddin,C. Boehme,G. Frenking, Coord. Chem.
Rev. 2000, 197,249 – 276; h) J. Uddin,G. Frenking, J. Am. Chem.
Soc. 2001, 123,1683 – 1693.
[3] a) H. Braunschweig,M. Colling,C. Kollann,H. G. Stammler,B.
Neumann, Angew. Chem. 2001, 113,2359 – 2361; Angew. Chem.
Int. Ed. 2001, 40,2298 – 2300; b) H. Braunschweig,M. Colling,C.
Hu,K. Radacki, Angew. Chem. 2003, 115,215 – 218; Angew.
Chem. Int. Ed. 2003, 42,205 – 208; c) H. Braunschweig,K.
Radacki,D. Rais,F. Seeler, Angew. Chem. 2006, 118,1087 –
1090; Angew. Chem. Int. Ed. 2006, 45,1066 – 1069; d) H.
[15] W. Haubold,J. Herdtle,W. Gollinger,W. Einholz, J. Organomet.
Chem. 1986, 315, 1 – 8.
[16] E. Mann,A. Musco, J. Chem. Soc. Dalton Trans. 1980,776 – 785.
[17] The crystal data of 4 and 5b were collected on a Bruker APEX
diffractometer with CCD area detector and graphite-monochro-
mated MoKa radiation. The structures were solved by using
direct methods,refined with the SHELX software package (G.
Sheldrick,University of Göttingen, 1997) and expanded by using
Fourier techniques. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were assigned to idealized
positions and were included in structure factor calculations.
Crystal data for 4: C51H83BBr2P2Pt, Mr = 1123.83,colorless
block,0.20 ” 0.17 ” 0.07 mm 3,monoclinic,space group
a = 13.1450(8), b = 23.0520(15), c = 16.9923(11) Š,
P21/c,
b =
105.2100(10)8, V= 4968.6(5) Š3, Z = 4, 1calcd = 1.502 gcmÀ3, m =
4.530 mmÀ1, F(000) = 2288, T= 173(2) K, R1 = 0.0399, wR2 =
0.0712,9856 independent reflections [2 q = 52.288] and 517
parameters. Crystal data for 5b: C70H79B2BrCl2F20P2Pt, Mr =
1729.79,colourless block,0.33 ” 0.31 ” 0.22 mm 3,monoclinic,
space group P21/n, a = 16.160(5), b = 24.965(7), c =
Braunschweig,M. Forster,K. Radacki,
Angew. Chem. 2006,
118,2187 – 2189; Angew. Chem. Int. Ed. 2006, 45,2132 – 2134.
[4] a) H. Braunschweig,T. Herbst,D. Rais,F. Seeler, Angew. Chem.
2005, 117,7627 – 7629; Angew. Chem. Int. Ed. 2005, 44,7461 –
7463; b) S. Aldridge,C. Jones,T. Gans-Eichler,A. Stasch,D. L.
Kays (nØe Coombs),N. D. Coombs,D. J. Willock, Angew. Chem.
2006, 118,6264 – 6268; Angew. Chem. Int. Ed. 2006, 45,6118 –
6122.
[5] H. Braunschweig,M. Colling,C. Kollann,K. Merz,K. Radacki,
Angew. Chem. 2001, 113,4327 – 4329; Angew. Chem. Int. Ed.
2001, 40,4198 – 4200.
18.780(5) Š, b = 110.240(12)8, V= 7109(3) Š3, Z = 4, 1calcd
=
1.616 gcmÀ3, m = 2.750 mmÀ1, F(000) = 3464, T= 173(2) K, R1 =
0.0317, wR2 = 0.0623,14109 independent reflections [2 q =
52.488] and 886 parameters. CCCDC-631652 and CCDC-
631653 contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
[6] a) D. L. Coombs,S. Aldridge,C. Jones,D. J. Willock,
J. Am.
Chem. Soc. 2003, 125,6356 – 6357; b) D. L. Kays (nØe Coombs),
J. K. Day,L.-L. Ooi,S. Aldridge, Angew. Chem. 2005, 117,7623 –
7626; Angew. Chem. Int. Ed. 2005, 44,7457 – 7460.
[18] T. S. Cameron,H. C. Clark,A. Linden,A. M. Nicholas,
Poly-
hedron 1990, 9,1683 – 2688.
[7] H. Braunschweig,K. Radacki,D. Rais,D. Scheschkewitz,
Angew. Chem. 2005, 117,5796 – 5799; Angew. Chem. Int. Ed.
2005, 44,5651 – 5654.
[19] W. Clegg,F. J. Lawler,G. Lesley,T. B. Marder,N. C. Norman,
A. G. Orpen,M. J. Quayle,C. R. Rice,A. J. Scott,F. E. S. Souza,
J. Organomet. Chem. 1998, 550,183 – 192.
[8] a) G. J. Irvine,C. E. F. Rickard,W. R. Roper,A. Williamson,
L. J. Wright, Angew. Chem. 2000, 112,978 – 980; Angew. Chem.
Int. Ed. 2000, 39,948 – 950; b) C. E. F. Rickard,W. R. Roper,A.
Williamson,L. J. Wright, Organometallics 2002, 21,4862 – 4872;
[20] C. N. Iverson,M. R. Smith III, J. Am. Chem. Soc. 1995, 117,
4403 – 4404.
[21] H. Braunschweig,K. Radacki,D. Rais,K. Uttinger,
Angew.
Chem. 2006, 118,169 – 172; Angew. Chem. Int. Ed. 2006, 45,162 –
165.
c) G. R. Clark,G. J. Irvine,W. R. Roper,L. J. Wright,
Organomet. Chem. 2003, 680,81 – 88.
J.
[22] J. Zhu,Z. Lin,T. B. Marder, Inorg. Chem. 2005, 44,9384 – 9390.
[23] Electronic structure calculations were performed with TURBO-
MOLE 5.8,R. Ahlrichs et al.,Quantum Chemistry Group,
University of Karlsruhe. See the Supporting Information for
details on the computations.
[9] a) M. R. Smith III, Prog. Inorg. Chem. 1999, 48,505 – 567;
b) G. J. Irvine,M. J. G. Lesley,T. B. Marder,N. C. Norman,
C. R. Rice,E. G. Robins,W. R. Roper,G. R. Whittell,L. J.
Wright, Chem. Rev. 1998, 98,2685 – 2722.
3982
www.angewandte.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2007, 46, 3979 –3982