Reactions of the dianion [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB 9H9]2- with transition-metal cations: Facile insertion and then extrusion of cluster vertexes

Article abstract of DOI:10.1021/ic048345w

The manganacarborane dianion in [N(PPh₃)₂][NEt ₄][1,1,1-(CO)₃-2-Ph-closo-1,2-MnCB₉H ₉] (1b) reacts with cationic transition metal-ligand fragments to give products in which the electrophilic metal groups (M′) are exo-polyhedrally attached to the {closo-1,2-MnCB₉} cage system via three-center two-electron B-H → M′ linkages and generally also by Mn-M′ bonds. With {Cu(PPh₃)}⁺, the Cu-Mn-Cu trimetallic species [1,6-{Cu(PPh₃)}-1,7-{Cu(PPh₃)}-6,7- (μ-H)₂-1,1,1-(CO)₃-2-Ph-closo-1,2-MnCB ₉H₇] (3a) is formed, whereas reactions with {M′(dppe)}²⁺ (M′ = Ni, Pd; dppe = Ph₂PCH ₂CH₂PPh₂) give [1,3-{Ni(dppe)}-3-(μ-H)-1,1, 1-(CO)₃-2-Ph-closo1,2-MnCB₉H₈] (5a) and [1,3,6-{Pd(dppe)}-3,6-(μ-H)₂-1,1,1-(CO)₃-2-Ph-closo1,2- MnCB₉H₇] (5b), both of which contain M′-Mn bonds. The latter reaction with M′ = Pt affords [3,6-{Pt(dppe)}-3,6-(μ-H) ₂-1,1,1-(CO)₃-2-Ph-closo-1,2-MnCB₉H ₇] (6), which lacks a Pt-Mn connectivity. Compound 6 itself spontaneously converts to [1-Ph-2,2,2-(CO)₃-8,8-(dppe)-hypercloso-8, 2,1-PtMnCB₉H₉] (7b) and thence to [3,6,7-{Mn(CO) ₃}-3,7-(μ-H)₂-1-Ph-6,6-(dppe)-closo-6,1-PtCB ₈H₆] (8). This sequence occurs via initial insertion of the {Pt(dppe)} unit and then extrusion of {Mn(CO)₃} and one {BH} vertex. In the presence of alcohols ROH, compound 6 is transformed to the 7-OR substituted analogues of 7b. X-ray diffraction studies were essential in elucidating the structures encountered in compounds 5-8 and hence in understanding their behavior.

Full text of DOI:10.1021/ic048345w

Inorg. Chem. 2005, 44, 2815−2825
-
Reactions of the Dianion [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2 with
Transition-Metal Cations: Facile Insertion and Then Extrusion of Cluster
Vertexes
Shaowu Du,† John C. Jeffery,‡ Jason A. Kautz,† Xiu Lian Lu,† Thomas D. McGrath,†
Thomas A. Miller,‡ T. Riis-Johannessen,‡ and F. Gordon A. Stone*,†
Department of Chemistry & Biochemistry, Baylor UniVersity, Waco, Texas 76798-7348, and
School of Chemistry, UniVersity of Bristol, Bristol BS8 1TS, U.K.
Received November 22, 2004
The manganacarborane dianion in [N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9] (1b) reacts with cationic
transition metal
attached to the
−
{
ligand fragments to give products in which the electrophilic metal groups (M
closo-1,2-MnCB9 cage system via three-center two-electron B linkages and generally
bonds. With Cu(PPh3) Mn Cu trimetallic species [1,6- Cu(PPh3) -1,7- Cu(PPh3)
+, the Cu
-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (3a) is formed, whereas reactions with (dppe)
Pd; dppe Ph2PCH2CH2PPh2) give [1,3- Ni(dppe) -3-( -H)-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H8] (5a) and [1,3,6-
Pd(dppe) -3,6-( -H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (5b), both of which contain M′−Mn bonds. The latter
reaction with M′ ) Pt affords [3,6- Pt(dppe) -3,6-( -H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (6), which lacks a
Pt Mn connectivity. Compound 6 itself spontaneously converts to [1-Ph-2,2,2-(CO)3-8,8-(dppe)-hypercloso-8,2,1-
PtMnCB9H9] (7b) and thence to [3,6,7- Mn(CO)3 -3,7-( -H)2-1-Ph-6,6-(dppe)-closo-6,1-PtCB8H6] (8). This sequence
occurs via initial insertion of the Pt(dppe) unit and then extrusion of Mn(CO)3 and one BH vertex. In the
presence of alcohols ROH, compound 6 is transformed to the 7-OR substituted analogues of 7b. X-ray diffraction
′) are exo-polyhedrally
}
−H F M′
also by Mn
6,7-(
−M
′
{
}
−
−
{
}
{
}-
2
+
µ
{
M
′
}
(M′ ) Ni,
)
{
}
µ
{
}
µ
{
}
µ
−
{
}
µ
{
}
{
}
{
}
studies were essential in elucidating the structures encountered in compounds 5−8 and hence in understanding
their behavior.
Introduction
behavior unprecedented in metallacarborane chemistry.3 In
seeking to broaden further the scope of this work, we have
begun to examine nonicosahedral species and have recently
reported dianionic, 11-vertex rhenium and manganese mono-
carborane complexes, namely, the salts [N(PPh3)2][NEt4]-
[1,1,1-(CO)3-2-Ph-closo-1,2-MCB9H9] [M ) Re (1a),4 Mn
(1b)5]. The rhenium compound 1a reacts with cationic
transition-element fragments to afford carborane-supported
polymetallic units that range from simple bimetallics,4,6
through trimetallics having either V-shaped4,6 or triangular6
cores, to a unique {ReIrAu2} “butterfly” species.6 This
During the four decades since the discovery of metalla-
carboranes by Hawthorne and co-workers,1 the field has been
dominated by metal dicarbollide species and, in particular,
by clusters with icosahedral {MC2B9} frameworks.2 We have
extended this area through studies of the corresponding metal
monocarbollide {MCB10} species, which have revealed
compounds that are complementary to the dicarbollide
systems, with some behaving similarly, but others displaying
* To whom correspondence should be addressed. E-mail:
gordon_stone@baylor.edu.
† Baylor University.
‡ University of Bristol.
(3) (a) McGrath, T. D.; Stone, F. G. A. J. Organomet. Chem. 2004, 689,
3891. (b) McGrath, T. D.; Stone, F. G. A. AdV. Organomet. Chem.
2005, 53, in press.
(1) Hawthorne, M. F.; Young, D. C.; Wegner, P. A. J. Am. Chem. Soc.
1965, 87, 1818.
(2) (a) Grimes, R. N. In ComprehensiVe Organometallic Chemistry;
Wilkinson, G., Abel, E. W., Stone, F. G. A., Eds.; Pergamon Press:
Oxford, U.K., 1982; Vol. 1, Section 5.5. (b) Grimes, R. N. In
ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F.
G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995;
Vol. 1, Chapter 9. (c) Grimes, R. N. Coord. Chem. ReV. 2000, 200-
202, 773.
(4) Du, S.; Kautz, J. A.; McGrath, T. D.; Stone, F. G. A. Organometallics
2003, 22, 2842.
(5) Du, S.; Farley, R. D.; Harvey, J. N.; Jeffrey, J. C.; Kautz, J. A.; Maher,
J. P.; McGrath, T. D.; Murphy, D. M.; Riis-Johannessen, T.; Stone,
F. G. A. Chem. Commun. 2003, 1846.
(6) Du, S.; Kautz, J. A.; McGrath, T. D.; Stone, F. G. A. Angew. Chem.,
Int. Ed. 2003, 42, 5728.
10.1021/ic048345w CCC: $30.25
Published on Web 03/12/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 8, 2005 2815

Du et al.
Chart 1
the highest-frequency CO band in the IR spectrum of 3a is
at 2002 cm-1, versus 2021 cm-1 for 2a. However, the
dianions of their parents 1b and 1a, respectively, show
similar differences in their spectroscopic properties, and
therefore, the apparent differences observed between com-
pounds 3a and 2a might be attributable to the nature of the
Mn versus Re centers, rather than to 3a exhibiting a structure
different from that of 2a. Unfortunately, single crystals of
3a suitable for an X-ray diffraction study were not available
1
to confirm this hypothesis. The H NMR spectrum of 3a
showed only resonances attributable to phenyl protons, with
unfortunately no signals for the B-H F Cu protons; the
latter would be useful in providing additional confirmation
of the structure in the absence of an X-ray study. However,
the resonances for such protons are rarely seen in 1H NMR
spectra because of extensive broadening by the adjacent
quadrupolar Cu and B nuclei and by fluxional processes that
are very rapid on the NMR time scale.8 Nevertheless, the
structure of 3a is believed to be similar to that of 2a on the
basis of the spectral similarities discussed above. We note,
moreover, in this connection that {M′(PPh3)} derivatives (M′
) Cu, Ag, Au) of the related manganese and rhenium
dicarbollide clusters [3,3,3-(CO)3-closo-3,1,2-MC2B9H11]-
(M ) Mn,9 Re10) all have very similar architectures and,
indeed, the Re-Cu, Re-Ag, Mn-Cu, and Mn-Au species
are all crystallographically isomorphous.
The dianion of 1a forms the bimetallic species [1,3-
{M′(dppe)}-3-(µ-H)-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H8]
[M′ ) Ni (4a), Pd (4b), Pt (4c), Chart 2]4 with sources of
the dications {M′(dppe)}2+. All three of these compounds
have similar NMR spectra and are believed to have similar
molecular structures, with that of the Re-Pt derivative
having been established by an X-ray diffraction study. The
latter experiment showed the exo-polyhedral platinum frag-
ment to be bonded to the rhenacarborane via a Re-Pt bond
and one B-H F Pt agostic-type interaction, the latter
involving the BH vertex in the γ position with respect to
finding prompted the initiation of parallel studies of the
reactivity of the manganese species 1b with transition-metal
cations. The results reported herein reveal some analogies
with the chemistry of 1a, but also some extraordinary
differences.
Results and Discussion
When the rhenium complex 1a is treated with sources of
the cations {M′(PPh3)}+ (M′ ) Cu, Au), the only metalla-
carborane products isolatedsregardless of stoichiometrys
are the trimetallic species [1,6-{M′(PPh3)}-1,7-{M′(PPh3)}-
6,7-(µ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H7] [M′ ) Cu
(2a), Au (2b), Chart 1].4 In parallel, reaction of the
manganese complex 1b with [CuCl(PPh3)]4 and Tl[PF6]
similarly gave a dicopper derivative, [1,6-{Cu(PPh3)}-1,7-
{Cu(PPh3)}-6,7-(µ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9-
H7] (3a, Chart 1), but the corresponding digold species 3b
(Chart 1) could not be isolated. It is known5 that the dianion
of compound 1b is readily oxidized by HgCl2, and conceiv-
ably, the {Au(PPh3)}+ cation affects 1b similarly. Indeed,
we have observed gold cluster species among the products
of the reaction between 1b and {Au(PPh3)}+, consistent with
oxidation of the manganacarborane and a partial reduction
of the gold reagent.7
the carbon within the Re-bound CBBBBB belt. An additional
long interaction to an adjacent â-BH was also noted. The
dianion of 1b behaves similarly to 1a and also forms
bimetallic complexes upon reaction with the same
{M′(dppe)}2+ dications. However, matters are rather more
complicated in the present system; this is particularly so for
the Mn-Pt case, which will therefore be discussed separately
from the Ni and Pd species.
Reaction (18 h) of 1b with [M′Cl2(dppe)] (1 equiv) and
Tl[PF6] (2 equiv) in CH2Cl2 affords the complexes [1,3-
{Ni(dppe)}-3-(µ-H)-1,1,1-(CO)3-2-Ph-closo-1,2-
MnCB9H8] (5a, Chart 2) and [1,3,6-{Pd(dppe)}-3,6-(µ-H)2-
Compound 3a was characterized by the data presented in
Tables 1-3. These data are broadly similar to those of 2a,4
but some significant differences are evident. Thus, for
example, their 11B{1H} and 31P{1H} NMR spectra show
similar chemical shifts and patterns, but the metal-bound CO
ligands appear different in the two compounds. The latter
groups give rise to a single broad resonance in the 13C{1H}
NMR spectrum at δ 218.4 for 3a, whereas two signals at δ
190.4 and 186.7 (2 × CO) are observed for 2a. Likewise,
(8) (a) Cabioch, J.-L.; Dossett, S. J.; Hart, I. J.; Pilotti, M. U.; Stone, F.
G. A. J. Chem. Soc., Dalton Trans. 1991, 519. (b) Batten, S. A.;
Jeffrey, J. C.; Jones, P. L.; Mullica, D. F.; Rudd, M. D.; Sappenfield,
E. L.; Stone, F. G. A.; Wolf, A. Inorg. Chem. 1997, 36, 2570. (c)
Ellis, D. D.; Franken, A.; Jelliss, P. A.; Kautz, J. A.; Stone, F. G. A.;
Yu, P.-Y. J. Chem. Soc., Dalton Trans. 2000, 2509.
(9) Hata, M.; Kautz, J. A.; Lu, X. L.; McGrath T. D.; Stone, F. G. A.
Organometallics 2004, 23, 3590.
(10) Ellis, D. D.; Jelliss, P. A.; Stone, F. G. A. Organometallics 1999, 18,
2509.
(7) Hall, K. P.; Mingos, D. M. P. Prog. Inorg. Chem. 1984, 32, 237.
2816 Inorganic Chemistry, Vol. 44, No. 8, 2005

Reactions of the [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2-
Table 1. Analytical and Physical Data
analb (%)
yield
(%)
ν
max(CO)a
(cm-1
compd
color
)
C
H
[1,6-{Cu(PPh3)}-1,7-{Cu(PPh3)}-6,7-(µ-H)2-1,1,1-(CO)3-2-Ph-
closo-1,2-MnCB9H7] (3a)
[1,3-{Ni(dppe)}-3-(µ-H)-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H8] (5a)
yellow
50
38
59
63
2002 s, 1945 s,
1916 s
2029 vs, 1987 m,
1962 m
2023 vs, 1968 w,
1934 m
ca. 2022 (sh) m,
2008 vs, 1949 m,
1920 m
54.7 (54.3)c
51.8 (51.9)d
51.5 (51.5)
45.7 (45.2)c
4.6 (4.4)
burgundy
indigo
4.7 (4.7)
4.7 (4.6)
4.0 (4.1)
[1,3,6-{Pd(dppe)}-3,6-(µ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (5b)
[3,6-{Pt(dppe)}-3,6-(µ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (6)
violet
[1-Ph-2,2,2-(CO)3-7-OEt-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H8] (7a)
[1-Ph-2,2,2-(CO)3-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H9] (7b)
[1-Ph-2,2,2-(CO)3-7-OMe-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H8] (7c)
[1-Ph-2,2,2-(CO)3-7-{O(CH2)2OH}-8,8-(dppe)-hypercloso-8,2,1-
PtMnCB9H8] (7d)
[1-Ph-2,2,2-(CO)3-7-{O(CH2)4OH}-8,8-(dppe)-hypercloso-8,2,1-
PtMnCB9H8] (7e)
[1-Ph-2,2,2-(CO)3-7-{OCH2CtCH}-8,8-(dppe)-hypercloso-8,2,1-
PtMnCB9H8] (7f)
green
green
green
green
72
83
71
48
2003 vs, 1938 m
2007 vs, 1944 m
2005 vs, 1939 m
2004 vs, 1940 m
47.2 (47.0)
45.3 (45.2)c
46.2 (46.4)
46.2 (46.2)
4.5 (4.4)
4.4 (4.1)
4.7 (4.2)
4.3 (4.3)
green
49
28
5
2004 vs, 1934 m
2005 vs, 1938 m
2022 vs, 1943 m
48.6 (48.5)e
49.2 (49.0)e
46.2 (46.4)f
5.3 (5.0)
5.1 (4.6)
4.0 (4.0)
green
[3,6,7-{Mn(CO)3}-3,7-(µ-H)2-1-Ph-6,6-(dppe)-closo-6,1-PtCB8H6] (8)
red-orange
a Measured in CH2Cl2; in addition, the spectra of all compounds show a broad, medium-intensity band at ca. 2500-2550 cm-1 due to B-H absorptions.
b Calculated values are given in parentheses. c Cocrystallized with 0.5 mol equiv of CH2Cl2. d Cocrystallized with 1.5 mol equiv of CH2Cl2. e Cocrystallized
with 0.5 mol equiv of C5H12. f Cocrystallized with 0.25 mol equiv of CH2Cl2.
Table 2. 1H and 13C NMR Dataa
compd
1H (δb)
13C (δc)
1b
8.05-7.00 (br m, 35H, Ph), 3.22 [q, J(HH) ) 7, 8H, NCH2], 1.28 (t,
12H, Me)
225.5 (CO), 156.5, 135.1-126.8 (Ph), 53.0 (CH2),
51.8 (br, cage C), 7.8 (Me)
3a
5a
5b
6
7.95 (m, 2H, cage Phortho), 7.54-7.44 (m, 30H, PPh), 7.32 (m, 2H, cage
218.4 (CO), 149.4, 136.4-126.1 (Ph), 67.5 (br, cage C)
Phmeta), 7.22 (m, 1H, cage Phpara
)
7.84 (br, 2H, cage Ph), 7.73-7.53 (br m, 20H, PPh), 7.30 (br, 3H, cage
223.2 (CO),d 149.6, 133.5-127.3 (Ph), 27.1 (br, CH2)
221.9 (CO),d 149.5, 133.5-127.1 (Ph), 27.4 (br, CH2)
Ph), 2.27, 2.23 (m × 2, 2H × 2, CH2 × 2)
7.85 (br, 2H, cage Ph), 7.65-7.55 (br, 20H, PPh), 7.29 (br, 3H, cage Ph),
2.43 (br, 4H, CH2)
7.94 (m, 2H, cage Phortho), 7.73-7.55 (m, 20H, PPh), 7.34 (m, 2H, cage
Phmeta), 7.25 (m, 1H, cage Phpara), 2.50 [d, J(PH) ) 18, 4H, CH2]
7.89 (br, 2H, cage Ph), 7.61-7.54 (m, 20H, PPh), 6.87 (m, 3H, cage
Ph), 3.54, 3.05 [dq × 2, 2J(HH) ) 11, 3J(HH) ) 7, 1H × 2, OCH × 2],
2.84, 2.30 (br m × 2, 2H × 2, PCH2 × 2), 0.79 (t, 3H, Me)
7.78 (br, 2H, cage Ph), 7.67-7.55 (m, 20H, PPh), 6.95 (m, 1H, cage
Ph), 6.89 (m, 2H, cage Ph), 2.84, 2.29 (br m × 2, 2H × 2, CH2 × 2)
7.66-7.49 (m, 22H, PPh and cage Ph), 6.94 (m, 3H, cage Ph), 3.22 (s,
3H, Me), 2.76, 2.39 (br m × 2, 2H × 2, PCH2 × 2)
221.0 (CO),e 150.2, 134.2-121.1 (Ph), 114.9 (br, cage
C),f 27.6 (br, CH2)
7a
222.0 (CO), 147.1, 134.8-124.2 (Ph), 66.3 (OCH2),
49.4 (br, cage C), 29.4, 26.8 (br × 2, PCH2 × 2),
17.5 (Me)
7b
7c
7d
221.3 (CO),d 147.3, 134.1-124.2 (Ph), 28.4 (br, CH2)
221.7 (CO), 147.2, 134.3-124.2 (Ph), 59.0 (OMe),
50.0 (br, cage C),f 28.6 (CH2)
221.4 (CO), 146.5, 134.8-124.0 (Ph), 71.6 (BOCH2),
62.9 (HOCH2), 48.8 (br, cage C), 28.6 (br, PCH2)
7.97-7.24 (br m, 22H, PPh and cage Ph),g 6.95 (m, 3H, cage Ph), 3.56,
3.26 (br m × 2, 1H × 2, BOCH × 2), 3.13 (m, 2H, HOCH2), 2.99, 2.59
(br m × 2, 2H × 2, PCH2 × 2)
7e
7f
8
7.95-7.26 (br m, 22H, PPh and cage Ph),g 6.92 (m, 3H, cage Ph), 3.54,
ca. 3.1 (br m × 2, 1H × 2, BOCH × 2), 3.04 (m, 2H, HOCH2), 2.90, 2.45
(br m × 2, 2H × 2, PCH2 × 2), 2.06 [br m, 4H, BOCH2(CH2)2CH2OH]
7.87-7.33 (br m, 22H, PPh and cage Ph), 6.95 (m, 3H, cage Ph), 4.98 (br,
1H, ≡CH), 4.13, 3.63 (m × 2, 1H × 2, OCH × 2), 2.87, 2.33 (br m × 2,
2H × 2, PCH2 × 2)
221.6 (CO), 146.9, 134.5-123.8 (Ph), 70.7 (BOCH2),
62.7 (HOCH2), 49.0 (br, cage C), 30.1, 29.8
(OCH2CH2CH2), 28.9 (br, PCH2)
221.5 (CO),d 146.6, 136.1-123.9 (Ph), 115.3 (C≡CH),
84.4 (CtCH), 71.8 (OCH2), 29.9, 26.8 (br × 2,
PCH2 × 2)
7.77-7.00 (m, 25H, Ph), 2.89 (br m, 2H, PCH2), 2.63, 2.24 (m × 2,
1H × 2, PCH2), ca. -9.3 (vbr, 2H, B-H F Mn)
208.7 (CO),d 139.9, 133.3-128.9 (Ph), 32.0 (br, CH2)
a Chemical shifts (δ) in ppm; coupling constants (J) in hertz; measurements at ambient temperatures, except where indicated otherwise, in CD2Cl2.
b Resonances for terminal BH protons occur as broad unresolved signals in the range δ from ca. -1 to +3. 1H-decoupled chemical shifts are positive to
c
high frequency of SiMe4. d The (broad) resonance for the cage carbon atom was not observed: the spectrum is weak as a result of poor solubility. e Recorded
at 243 K. f Tentative assignment. g Resonance for terminal OH proton was not observed.
1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (5b, Chart 2). These
species were characterized by the data in Tables 1-3 and
by an X-ray diffraction study of 5b. The latter afforded the
structure shown in Figure 1. The molecule consists of a five-
coordinate Pd(II) fragment that is bonded exo-polyhedrally
to the manganacarborane surface. In addition to the two
cisoid phosphorus donors, the coordination at the PdII center
in 5b is completed by a dative bond from the manganese
vertex and by two three-center, two-electron B-H F Pd
agostic-type interactions [Pd(1)‚‚‚H(3) 2.56(4), Pd(1)‚‚‚B(3)
2.257(5); Pd(1)‚‚‚H(6) 2.31(4), Pd(1)‚‚‚B(6) 2.356(5) Å]. As
discussed previously,4 precise electron distributions cannot
definitively be assigned to the metal centers in molecules of
type 5. Different canonical forms with or without metal-
metal donor bonds equally represent the electron counts at
the metal centers. The two B-H F Pd bonds in 5b involve
the boron vertexes B(3) and B(6), which are in γ and â sites,
respectively, relative to the carbon atom in the Mn-bound
Inorganic Chemistry, Vol. 44, No. 8, 2005 2817

Du et al.
Table 3. 11B and 31P NMR Dataa
compd
11B (δb)
31P (δc)
3a
5a
5b
6
15.5, 7.4, 3.9, -7.9 (2B), -26.9 (2B), -28.5 (2B)
28.7 (br), 15.6, 12.4, ca. 8.8 (vbr), -2.6 (br, 2B), -12.2 (3B)
25.3 (br, 3B), 7.9 (br), -5.0 (vbr, 3B),-11.4 (2B)
16.1, 8.6, 4.7 (3B), -10.2 (2B), -16.0 (2B)
8.2 (br)
58.4
63.1
57.4 (3290)
7a
7b
7c
7d
7e
7f
8
56.7, 22.6, ca. 15.8 (sh), 13.3 (2B), 2.9, -4.5 (2B), -20.3
59.2, 22.8, 15.1 (2B), 11.1, 7.1, -1.2, -4.0, -20.7
58.3, 22.6, 14.3 (2B), ca. 12.2 (sh), 4.3, -3.9 (2B), -20.6
56.7, 22.5, ca. 16.6 (sh), 14.0 (2B), 2.1, -4.4 (2B), -20.2
57.2, 22.6, 13.7 (br, 3B), 2.8, -4.4 (2B), -20.3
58.4, 22.9, ca. 15.5 (sh), 13.8 (2B), 2.7, -4.4 (2B), -20.2
50.2, 4.5 (br), ca. -3.6 (sh), -4.2, -7.7, -12.8, -19.4, -21.4
54.4 (2570), 52.4 (2610)
55.9 (2580)
55.0 (2520), 52.7 (2650)
53.7 (2620), 52.8 (2590)
53.8 (2560), 51.9 (2620)
54.3 (2520), 52.9 (2660)
34.3 (2960), 33.6 (2780)
b
a Chemical shifts (δ) in ppm; measurements at ambient temperatures in CD2Cl2. 1H-decoupled chemical shifts are positive to high frequency of BF3‚Et2O
(external); resonances are of unit integral except where indicated otherwise; and where peaks are broad, the assigned integrals are somewhat subjective.
c
1
1H-decoupled chemical shifts are positive to high frequency of 85% H3PO4 (external). Numbers in parentheses are J(PtP) coupling constants (Hz). The
spectra for compounds 6-8 are all rather broad and suffer from low sample concentration as a result of poor solubility: quoted coupling constants are,
2
therefore, somewhat approximate, and J(PP) couplings could not be resolved.
Chart 2
Figure 1. Structure of 5b showing the crystallographic labeling scheme.
In this and the subsequent figures, thermal ellipsoids are drawn at the 40%
probability level, and for clarity, only the ipso carbon atom of the phosphine
phenyl rings and only chemical significant H atoms are shown. Selected
CBBBBB face. Overall, the structure of 5b is quite similar
to that found in 4c, save that the agostic-type bridges in 5b
are approximately equivalent, whereas in 4c, the B-H F
Pt interaction involving the γ-BH is much stronger than that
internuclear distances (Å) and angles (deg): Mn(1)-Pd(1) 2.6629(7),
Mn(1)-C(2) 2.078(4), Mn(1)-B(3) 2.205(5), Mn(1)-B(4) 2.312(5),
involving the â-BH. Although the Pd‚‚‚B distances here are
Mn(1)-B(5) 2.362(5), Mn(1)-B(6) 2.466(5), Mn(1)-B(7) 2.386(5), B(3)‚‚‚
similar to those seen previously in comparable species
[2.333(4)-2.406(4) Å],11,12 the Pd‚‚‚H distances determined
for 5b are much longer than those in the same compounds
(ca. 1.74-1.95 Å). In effect, the {Pd(1)P(1)P(2)} plane in
5b is twisted so that it lies between those through {Mn(1)-
Pd(1)B(3)} and {Mn(1)Pd(1)B(6)} and this effectively
lengthens the observed Pd‚‚‚H distances. A vector to Pd(1)
from a position that is an average of the two B-H F Pd
bridges would complete a more genuinely square-planar
coordination sphere around the palladium center. The
observed “twisting”, however, likely occurs in order most
effectively to satisfy a five-coordinate geometry; it might
also be affected by crystal packing.
Pd(1) 2.257(5), Pd(1)‚‚‚H(3) 2.56(4), B(6)‚‚‚Pd(1) 2.356(5), Pd(1)‚‚‚H(6)
2.31(4), C(13)‚‚‚Pd(1) 2.450(4); B(3)-Pd(1)-P(1) 104.75(12), B(3)-
Pd(1)-P(2) 163.78(14), P(1)-Pd(1)-B(6) 105.20(12), P(2)-Pd(1)-B(6)
147.73(13), P(1)-Pd(1)-Mn(1) 157.15(3), P(2)-Pd(1)-Mn(1) 118.46(3).
structurally characterized, the metal-metal bond is generally
constrained by a bridging ligand. In compound 5b, the
carborane moiety could also be considered to bridge the Mn-
Pd connectivity, although it arguably does so less restrictively
than units such as Ph2PCH2PPh2 or µ-PPh2 in previously
reported examples.13 These considerations notwithstanding,
the Mn-Pd distance in 5b is within the range of those
observed previously (ca. 2.58-2.85 Å).13 There is also one
additional, longer interaction involving the palladium atom:
this is to the carbon atom of a Mn-bound CO group [Pd(1)‚‚‚
C(13) is 2.450(4) Å]. As a result of the latter, the Mn(1)-
C(13)-O(13) angle [169.3(4)°] is slightly distorted from
linearity. A similar feature is seen in the crystal structure of
4c.4
The presence in 5b of a Mn-Pd bond [Mn(1)-Pd(1) is
2.6627(7) Å] is noteworthy as relatively few examples of
such exist in the literature13 and, of those reported and
(11) Blandford, I.; Jeffery, J. C.; Jelliss, P. A.; Stone, F. G. A. Organo-
metallics 1998, 17, 1402.
(12) Lassahn, P.-G.; Lozan, V.; Wu, B.; Weller, A. S.; Janiak, C. Dalton
Trans. 2003, 4437.
(13) Hoskins, B. F.; Steen, R. J.; Turney, T. W. J. Chem. Soc., Dalton
Trans. 1984, 1831. Braunstein, P.; de Jesus, E.; Tiripicchio, A. J.
Organomet. Chem. 1989, 368, C5. Braunstein, P.; Oswald, B.;
Tiripicchio, A.; Camellini, M. T. Angew. Chem., Int. Ed. Engl. 1990,
29, 1140. Brunet, L.; Mercier, F.; Ricard, L.; Mathey, F. Angew.
Chem., Int. Ed. Engl. 1994, 33, 742. Braunstein, P.; de Meric de
Bellefon, C.; Ries, M.; Fischer, J. Organometallics 1998, 7, 332. Liu,
Y.; Lee, K. H.; Vittal, J. J.; Hor, T. S. A. J. Chem. Soc., Dalton Trans.
2002, 2747. Adams, R. D.; Kwon, O.-S. J. Cluster Sci. 2003, 14, 367.
2818 Inorganic Chemistry, Vol. 44, No. 8, 2005

Reactions of the [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2-
Scheme 1. Formation of Compounds 7 and 8 from Compound 6
Figure 2. Structure of 6 showing the crystallographic labeling scheme.
Selected internuclear distances (Å) and angles (deg): Mn-C(2) 2.083(6),
Mn-B(3) 2.151(7), Mn-B(4) 2.314(8), Mn-B(5) 2.403(7), Mn-B(6)
2.379(8), Mn-B(7) 2.342(8), B(3)‚‚‚Pt 2.365(7), Pt‚‚‚H(3) 2.27(7),
B(6)‚‚‚Pt 2.205(7), Pt-H(6) 1.63(4); P(1)-Pt-B(3) 167.2(2), P(2)-Pt-
B(3) 107.8(2), B(6)-Pt-P(1) 124.9(2), B(6)-Pt-P(2) 150.6(2).
migration of the exo-polyhedral fragment. Unfortunately, the
broadness of the peaks in the 11B{1H} NMR spectrum for
5b precludes the drawing of many conclusions about this
species.
Initial attempts to prepare a platinum analogue of com-
pounds 5 via a similar synthetic route were, surprisingly,
complicated by the presence in the product mixture of up to
four different species. Moreover, all four of these species
were confirmed spectroscopically to contain the component
platinum, manganese, and carborane moieties. The picture
was further confused by the observation of interconversion
of these compounds. Thus, the presumed “expected” product,
an initially formed dark violet species, over time gave two
different green compounds and thence to a final red-orange
product. Spectroscopic data alone could not unravel the
details of this sequence (summarized in Scheme 1); the
results from crystal structure determinations were essential
in understanding this system.
Reaction between 1b, [PtCl2(dppe)], and Tl[PF6] (1:1:2
ratio) gives, within ca. 15 min, a violet compound whose
identity was confirmed as [3,6-{Pt(dppe)}-3,6-(µ-H)2-1,1,1-
(CO)3-2-Ph-closo-1,2-MnCB9H7] (6) by an X-ray diffraction
study. The structure of 6 is shown in Figure 2, and the most
notable feature is the absence of a Mn-Pt bond (Mn‚‚‚Pt >
3.6 Å). Instead, the exo-polyhedral {Pt(dppe)} unit is
anchored to the cluster surface solely by two B-H F Pt
agostic-type interactions. These involve the vertexes B(3)
and B(6) that are in γ and â sites, respectively, in the
The spectroscopic data for complexes 5a and 5b presented
in Tables 1-3 reveal some similarities but some contrasts
between the two species, as well as only limited parallels
with compounds 4.4 For example, all of compounds 4 and 5
have comparable IR spectrasalbeit with some differences
in the band intensities for 5a. However, although 5a has 11
B
NMR parameters very similar to those for compounds 4,
those for 5b are very different. On the basis of the former
observation, the nickel species is reasonably assumed to have
a structure comparable to that of complexes 4. The X-ray
diffraction study discussed above has already revealed a
somewhat different geometry for 5b; in solution, of course,
both structural types might be present (possibly along with
others), and the observed spectra would be the time-averaged
result. Notably, both compounds 5 show only a single 31P-
{1H} resonance at ambient temperatures. This would not be
expected on the basis of the solid-state structure alone and
indicates that the exo-polyhedral fragment undergoes ex-
change behavior that renders the two phosphorus atom
environments equivalent on the NMR time scale. (Unfortu-
nately, the poor solubilities of these complexes precluded a
low-temperature study.) One such mechanism for dynamic
behavior was earlier proposed for compounds 4.4 However,
as in the Re system, the pattern of intensities in the 11B{1H}
NMR spectra of 5a shows the cluster to retain overall
asymmetry during the fluxional process, and thus, the {M′P2}
fragment remains always on the same side of the notional
mirror plane of the {MnCB9} core. Indeed, the observed
close approach of the exo-{Pd(dppe)} moiety to both BH(3)
and BH(6) in 5b in the solid state tends to lend support to
the suggested4 involvement of both of these vertexes in the
manganese-bound CBBBBB ring, with distances [B(3)‚‚‚Pt
2.365(7), Pt‚‚‚H(3) 2.27(7); B(6)‚‚‚Pt 2.205(7), Pt-H(6)
1.63(4) Å] that compare well with those of the sole
B-H F Pt unit in 4c [B(3)‚‚‚Pt 2.266(11), Pt‚‚‚H(3) 2.04-
(11) Å].4
By itself, the geometry of 6 is relatively unremarkable, as
there are multiple examples of exo-polyhedral fragments
anchored to metallacarboranes without metal-metal bonds
being formed.14 However, in the present context, the structure
(14) For example: Hodson, B. E.; McGrath, T. D.; Stone. F. G. A. Dalton
Trans. 2004, 2570. Hodson, B. E.; McGrath, T. D.; Stone. F. G. A.
Organometallics 2005, 24, 1638-1646. See also refs 3b and 8c and
other references therein.
Inorganic Chemistry, Vol. 44, No. 8, 2005 2819

Du et al.
of compound 6 does contrast with those determined for 4c
and 5b and, hence, with all five of the analogous compounds
4 and 5. The changes observed in the sequence {4 and 5a}
f 5b f 6 can be viewed as a smooth progression from
compounds with strong metal-metal bonding and only a
single B-H F M′ bond through to a compound with only
B-H F Pt bonds. This absence of a direct Mn-Pt bond is
very likely a consequence of an energy and size “mismatch”
between manganese- and platinum-based orbitals.
under these circumstances, a second green species always
accompanied 6 in small amounts. Moreover, solutions of 6
also became green after several hours. In each case, the
complex formed was the same and corresponds to the second
green product that was obtained in trace amounts during the
original attempts to prepare compound 6, as discussed above.
This product is [1-Ph-2,2,2-(CO)3-8,8-(dppe)-hypercloso-
8,2,1-PtMnCB9H9] (7b); it is, in fact, an isomer of 6 and is
the non-B-substituted analogue of 7a. Its structure was
likewise confirmed by a preliminary X-ray diffraction study
and by comparison of its NMR data with those of 7a (see
below).
The NMR spectroscopic properties of compound 6 (Tables
2 and 3) also reveal some variation from compounds 4 and
5. In particular, the 11B{1H} NMR parameters for 6 are
noticeably different from those of its ostensible analogues 4
and 5a. Indeed, the 1:1:3 (1 + 2 coincidence):2:2 intensity
pattern in this spectrum is suggestive of overall molecular
mirror symmetry on the NMR time scale, a feature that is
absent from the data for compounds 4 and 5a. The observa-
tion of only a single resonance (with 195Pt satellites) in the
It was of interest to establish whether other alcohols could
be used as substrates to form analogues of compound 7a. In
so doing, it was hoped that some additional functionality
could be appended via the boron vertexes of the {PtMnCB9}
cluster: the introduction of substituents to (hetero)boranes
is an area of considerable current interest.3b,9,15 Thus,
treatment of CH2Cl2 solutions of 6 with various alcohols
ROH gave the B-substituted products [1-Ph-2,2,2-(CO)3-7-
OR-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H8] [R ) Me (7c),
(CH2)2OH (7d), (CH2)4OH (7e), CH2CtCH (7f)]. It had been
hoped that using diols in this reaction would afford linked
bis(cage) species, but this proved not to be the case. Never-
theless, the additional terminal functionality that remains on
the substituents in compounds 7d-7f bodes well for future
reactivity studies that might exploit these features. Attempts
were also made to employ in this reaction other substrates
containing a potentially protonic H atom that could combine
with a boron-bound hydride and eliminate as H2, but these
proved unsuccessful. With secondary amines, for example,
the exo-polyhedral platinum fragment was simply abstracted
by the N donor: spectroscopic analysis of the product
mixture showed the anion of 1b as the only metallacarborane
product. It should also be noted at this juncture that com-
pounds 5 appear to be relatively stable in the presence of
traces of EtOH but decompose with excess of the alcohol:
analysis of the details of these reactions are continuing.
An X-ray diffraction study of compound 7d revealed the
structure shown in Figure 3. The preliminary structural
determinations for compounds 7a and 7b mentioned earlier
showed identical connectivity patterns, with the only differ-
ences being the substituent bound to B(7). In 7d, specifically,
this substituent is an -OCH2CH2OH unit, with B(7)-O(71)
being 1.392(5) Å. Perhaps surprisingly, the hydrogen atom
of the pendant OH group in 7d does not hydrogen bond with
the OH of an adjacent molecule. Instead, this hydrogen atom
appears oriented so that it points toward the center of one
of the phosphine phenyl rings, forming an intramolecular
1
31P{1H} NMR spectrum of 6 and only a single broad H
NMR signal for the phosphine methylene groups indicates
that the exo-polyhedral fragment is fluxional with respect
to the cluster surface. Combined with the 11B data, this tends
to suggest an exchange process in which the platinum
fragment migrates across the mirror plane of the {MnCB9}
core. The extremes of such a process might involve, for
example, the two enantiomers observed in the solid state,
but whether any intermediate has a Mn-Pt bond can only
be speculated at this stage. It is notable, however, that pure
samples of compound 6, upon dissolution, give an infrared
spectrum (Table 1) whose CO stretching region clearly shows
four bands, indicating the presence of more than one
distinguishable species on the IR time scale. On the basis of
this information alone, of course, it is impossible to obtain
definitive identities. However, there is the tantalizing sug-
gestion of a metal-metal bonded species similar to the Ni
and Pd derivatives, with the highest-frequency CO stretch
(ca. 2022 cm-1, shoulder) corresponding closely to that [2029
(5a), 2023 (5b) cm-1] in compounds 5.
The second product identified in the original synthesis of
6 was the closed, 12-vertex species [1-Ph-2,2,2-(CO)3-7-OEt-
8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H8] (7a), identified as
such by a preliminary X-ray diffraction structural study. In
this compound, the formerly exo-polyhedral platinum center
has inserted into the 11-vertex {closo-1,2-MnCB9} cluster
of the precursor to give a species with pseudo-icosahedral
{8,2,1-PtMnCB9} architecture. In addition, one boron vertex
[B(7)] bears an ethoxy substituent. The origin of the latter
group was identified as traces of residual EtOH from the
workup of the starting material 1b. When 1b was scrupu-
lously freed of EtOH by recrystallization from acetone/
petroleum ether, no 7a was observed, and under these
conditions, compound 6 was obtained in superior yields and
as essentially the only product after a reaction time of ca.
30 min. Conversely, deliberate addition of EtOH to solutions
of 6sor to an otherwise “alcohol-free” mixture of 1b, [PtCl2-
(dppe)], and Tl[PF6]sreadily afforded compound 7a.
Although yields of 6 could be improved by elimination
of EtOH and of the side formation of compound 7a, even
(15) Other recent examples include: Robertson, S.; Ellis, D.; McGrath, T.
D.; Rosair, G. M.; Welch, A. J. Polyhedron 2002, 22, 1293. Yao, H.;
Grimes, R. N.; Corsini, M.; Zanello, P. Organometallics 2003, 22,
4381. Rojo, I.; Teixidor, F.; Vin˜as, C.; Kiveka¨s, R.; Sillanpa¨a¨, R. Chem.
Eur. J. 2003, 9, 4311. Olejniczak, A. B.; Plesek, J.; Kriz, O.;
Lesnikowski, Z. J. Angew. Chem., Int. Ed. 2003, 42, 5740. Hawthorne,
M. F. Pure Appl. Chem. 2003, 75, 1157. Franken, A.; Carr, M. J.;
Clegg, W.; Kilner, C. A.; Kennedy, J. D. Dalton Trans. 2004, 3552.
See also: Grimes, R. N. Coord. Chem. ReV. 2000, 200-202, 773.
Davidson, M. G., Hughes, A. K., Marder, T. B., Wade, K., Eds.;
Contemporary Boron Chemistry; Royal Society of Chemistry: Cam-
bridge, U.K., 2000.
2820 Inorganic Chemistry, Vol. 44, No. 8, 2005

Reactions of the [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2-
Apart from this feature, the structure is at first sight
relatively unremarkable, and the geometry of the cluster in
compounds 7 is confirmed as a closed 12-vertex {8,2,1-
PtMnCB9} pseudo-icosahedron. In this structure, the man-
ganese center is coordinated on one side by three CO ligands
and on the other side by the CBBBB face of a {nido-4,7-
PtCB9} cage; the alkoxide-substituted boron vertex is in a â
position with respect to the carbon atom within this face.
This â site is well established as the one favored for
substitution in the related compounds where the CBBBB face
of a {nido-7-CB10} ligand is bonded to a metal center.3b
Around the platinum vertex, the coordination sphere com-
prises the two phosphorus donors of the dppe ligand, plus
the five boron atoms in the η5-B5 face of a {nido-3,2-
MnCB9} unit. The latter coordination, with the cage carbon
atom in the “upper” belt of the ligand, resembles the
platinum-to-carborane bonding in a PtIV polytellurium species
where a {Pt(PEt3)L2} unit [L2 ) Te(Ph)-Pt(TePh)PEt3-
Te(Ph)] is coordinated by the η5-B5 face of a {nido-2-CB10}
carborane.17 Isolobal replacement of {Mn(CO)3} ¶ {BH}+
vertexes would relate the two platinum-bound subclusters.
The substituted boron atom B(7) is adjacent also to the
platinum center in 7d, and of the two boron atoms bonded
to both metal vertexes, this one is the more distant from the
cage carbon; hence, substitution here is readily understood
in terms of this being the most hydridic {BH} in the parent
(that is, in 7b).
The cluster architecture of compounds 7 presents an
interesting conundrum in electron-counting terms. If the
{PtP2}0 unit is considered to be a two-electron donor for
cluster bonding, as is usual,18 then insertion of a {PtP2}2+
unit into the conventionally closo 11-vertex {MnCB9} cluster
(with 24 skeletal electrons, i.e., 2n + 2 cluster bonding
pairs,19 where n is the number of cluster vertexes) would
not increase the cluster electron count. Thus, the {PtMnCB9}
cluster of 7 would then be described as hypercloso,20 having
2n skeletal bonding pairs. However, the connectivity pattern
in compounds 7 resembles that of a conventional closo-
structured icosahedron, rather than that normally found in
hypercloso 12-vertex species.21 This observation might imply
that the {PtP2} unit behaves here as a four-electron contribu-
tor, as a result of the platinum center tending toward a 16-
electron configuration and donating an additional electron
pair from a lower lying, filled orbital.18,22
Figure 3. Two views of the structure of 7d showing the crystallographic
labeling scheme: (a) general perspective and (b) view, including the relevant
P-Ph ring, that emphasizes the O-H‚‚‚π hydrogen bond. Selected
internuclear distances (Å) and angles (deg): Mn-C(1) 2.203(4), Mn-B(3)
2.130(5), Mn-B(6) 2.173(5), Mn-B(7) 2.136(5), Mn-B(11) 2.265(5),
B(3)-Pt 2.258(5), B(4)-Pt 2.191(4), B(7)-O(71) 1.392(5), B(7)-Pt
2.265(5), B(9)-Pt 2.263(5), B(12)-Pt 2.268(5); O(71)-B(7)-Mn 121.8(3),
O(71)-B(7)-Pt 96.5(3), B(7)-Pt-P(2) 127.25(12), B(7)-Pt-P(1)
113.85(13). The H(72)‚‚‚X distance is ca. 2.57 Å, the O(71)‚‚‚X distance
is ca. 3.35 Å, and the O-H‚‚‚X angle is ca. 156°; X is the C(12n) (n )
1-6) ring centroid.
(17) Batten, S. A.; Jeffrey, J. C.; Rees, L. H.; Rudd, M. D.; Stone, F. G.
A. J. Chem. Soc., Dalton Trans. 1998, 2839.
(18) O’Neill, M. E.; Wade, K. In ComprehensiVe Organometallic Chem-
istry; Wilkinson, G., Abel, E. W., Stone, F. G. A., Eds.; Pergamon
Press: Oxford, U.K., 1982; Vol. 1, Section 1.
O-H‚‚‚π hydrogen bond (Figure 3b).16 The H‚‚‚X (X ) ring
centroid) distance is ca. 2.57 Å, while O(71)‚‚‚X is ca. 3.35
Å and the O-H‚‚‚X angle is ca. 156 °, typical values for
such interactions in organometallic species.16c
(19) (a) Wade, K. AdV. Inorg. Chem. Radiochem. 1976, 18, 1. (b) Mingos,
D. M. P. Acc. Chem. Res. 1984, 17, 311.
(20) Baker, R. T. Inorg. Chem. 1986, 25, 109. Johnston, R. L.; Mingos,
D. M. P. Inorg. Chem. 1986, 25, 3321; Johnston, R. L.; Mingos, D.
M. P.; Sherwood, P. New J. Chem. 1991, 15, 831.
(21) Attfield, M. J.; Howard, J. A. K.; Jelfs, A. N. de M.; Nunn, C. M.;
Stone, F. G. A. J. Chem. Soc., Dalton Trans. 1987, 2219. Carr, N.;
Mullica, D. F.; Sappenfield, E. L.; Stone, F. G. A. Organometallics
1992, 11, 3697.
(22) See, for example: Kennedy, J. D. In The Borane, Carborane,
Carbocation Continuum; Casanova, J., Ed.; Wiley: New York, 1998;
p 85 and references therein.
(16) (a) Viswamitra, M. A.; Radhakrishnan, R.; Bandekar, J.; Deriaju, G.
R. J. Am. Chem. Soc. 1993, 115, 4868. (b) Malone, J. F.; Murray, C.
M.; Charlton, M. H.; Docherty, R.; Lavery, A. J. J. Chem. Soc.,
Faraday Trans. 1997, 93, 3429. (c) Braga, D.; Grepioni, F.; Tedesco,
E. Organometallics 1998, 17, 2669.
Inorganic Chemistry, Vol. 44, No. 8, 2005 2821

Du et al.
Chart 3
The mechanism of formation of compounds 7 at this time
remains unclear. It is well-known23 that {PtL2}0 units can
oxidatively insert into closo carboranes, but in those cases,
a zerovalent (d10) platinum center is involved, and this would
require a very significant electron redistribution in 6.
Moreover, such reactions of the closo 11-vertex carboranes
2,3-Me2-closo-2,3-C2B9H9, [closo-2-CB10H11]- and 2-NMe3-
closo-2-CB10H10 give products where the platinum and
carbon vertexes remain mutually adjacent.24,25 This is not
the case in compounds 7, but in any event, it could be argued,
for example, that a sterically induced cluster rearrangement26
occurs after insertion or, indeed, that these oxidative insertion
reactions might proceed differently with metallacarborane
substrates. The latter suggestion might gain support from
earlier observations of the reaction of the {Pt(PEt3)2}0
fragment with [1-(η-C5H5)-closo-1,2,4-CoC2B8H10].24 The
product of that reaction, identified as [4-(η-C5H5)-7,7-(PEt3)2-
closo-7,4,1,2-PtCoC2B8H10], can be compared with com-
pounds 7 (cluster structures A and B, respectively, in Chart
3), and it is encouraging to note considerable similarities
between the arrangement of the vertexes in the two clusters.
All compounds 7 are dark green and show the expected
close mutual similarities in their spectral data (Tables 1-3).
Their 31P{1H} spectra all show two signals, each with 195Pt
satellites, indicating restricted rotation of the {PtP2} unit with
Figure 4. Structure of 8 showing the crystallographic labeling scheme.
Selected internuclear distances (Å) and angles (deg): Pt-Mn 2.8088(9),
Pt-B(2) 2.271(6), Pt-B(3) 2.212(6), Pt-B(7) 2.317(6), Pt-B(9) 2.395(6),
Pt-B(10) 2.127(6), Mn‚‚‚B(3) 2.220(6), Mn-H(3) 1.90(6), Mn‚‚‚B(7)
2.181(6), Mn-H(7) 1.80(6); C(2)-Mn-Pt 93.8(2), C(3)-Mn-Pt 164.2(2),
C(4)-Mn-Pt 105.43(19), B(3)-Mn-Pt 50.56(16), B(7)-Mn-Pt 53.57(16),
P(1)-Pt-Mn 104.26(4), P(2)-Pt-Mn 106.84(4).
all generally rather broad, and so upon retention of proton
coupling, most resonances showed only further broadening
and no doublet structure could be revealed. It was, therefore,
impossible to establish with certainty the chemical shift of
the substituted boron atom.
Each of compounds 7 is unstable, and 7b is particularly
so. Whereas 7a and 7c-7f apparently decompose slowly but
entirely and give no identifiable metallacarborane products,
7b upon decomposition gives small amounts of the red-
orange species that was the fourth productscompound 8s
isolated in the original attempted synthesis of compound 6.
Indeed, traces of compound 8 are generally also observed
during the deliberate synthesis of the other compounds 7 from
6, this being presumably via 7b, which must always be
competitively (but relatively much more slowly) formed
alongside 7a and 7c-7f. It is notable in this connection that
compound 7b cannot be purified by column chromatography,
as this significantly accelerates its conversion to compound
8. It is apparent that other metallacarboranes might also be
formed in the latter processsincluding, for example, a
possible nine-boron analogue of compound 8sbut these seem
generally to be somewhat transient and unstable and are
formed only in very low and variable yields.
respect to the ligating CBBBB face of the manganacarborane.
For 7b, the two 31P resonances are accidentally coincident,
reflecting the greater symmetry of the unsubstituted man-
1
ganacarborane face. In addition to H and 13C{1H} NMR
resonances for the cage Ph and metal-bound dppe and CO
ligands, all of the boron-bound OR groups give rise to signals
in expected positions and display no unusual perturbations
upon attachment to the metallacarborane. The cage carbon
atom (where discernible) resonates at around δ 50 in the
13C{1H} NMR spectra of all of compounds 7, a typical
position for such a vertex. In their 11B{1H} NMR spectra,
compounds 7 show nine separate resonances (with some
coincidences), as required by the lack of cluster symmetry.
These occur in the region δ from ca. 60 to -20, a relatively
broad range for a closo carbametallaborane, and might be
indicative of some loss of cluster electron density, consistent
with a hypercloso descriptor20,27 as discussed above. Unfor-
tunately, the 11B{1H} NMR signals for these compounds are
Initial spectroscopic data, as noted earlier, confirmed the
presence of platinum, manganese, and carborane moieties
in compound 8, but their precise arrangement and constitution
was established only following a single-crystal X-ray dif-
fraction experiment, whose results are depicted in Figure 4.
(23) Stone, F. G. A. J. Organomet. Chem. 1977, 100, 257.
(24) Green, M.; Spencer, J. L.; Stone, F. G. A.; Welch, A. J. J. Chem.
Soc., Dalton Trans. 1975, 179.
(25) Carroll, W. E.; Green, M.; Stone, F. G. A.; Welch, A. J. J. Chem.
Soc., Dalton Trans. 1975, 2263.
(26) For example: Baghurst, D. R.; Copley, R. C. B.; Fleischer, H.; Mingos,
D. M. P.; Kyd, G. O.; Yellowlees, L. J.; Welch, A. J.; Spalding, T.
R.; O’Connell, D. J. Organomet. Chem. 1993, 447, C14.
(27) Jung, C. W.; Baker, R. T.; Hawthorne, M. F. J. Am. Chem. Soc. 1981,
103, 810. Littger, R.; Englich, U.; Ruhlandt-Senge, K.; Spencer, J. T.
Angew. Chem., Int. Ed. 2000, 39, 1472.
2822 Inorganic Chemistry, Vol. 44, No. 8, 2005

Reactions of the [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2-
The molecule is identified as [3,6,7-{Mn(CO)3}-3,7-(µ-H)2-
1-Ph-6,6-(dppe)-closo-6,1-PtCB8H6] and consists of a central
{closo-6,1-PtCB8} core to which is bonded an exo-polyhedral
{Mn(CO)3} moiety. In addition to this extrusion of the
manganese vertex from the precursor 7b, a {BH} vertex has
also been lost. Within the {PtCB8} unit, the carbon atom
adopts the four-coordinate site, while the metal center is five-
coordinate, as would be expected. These two vertexes are
mutually nonadjacent, a feature preserved from the precursor
7b. Only one other simple metallacarborane with this atom
arrangement has hitherto been structurally characterized,
namely, the iridacarborane [6-H-6,6,10-(PPh3)3-closo-6,1-
IrCB8H8],28 although that compound was prepared directly
from the eight-boron carborane [arachno-4-CB8H13]-. In
addition, each of the {MoCB8} subclusters in the recently
reported “macropolyhedral” anion [(CO)2MoB16H15C2Ph2]-
has the same relative disposition of metal and carbon
vertexes; this, too, was prepared from an eight-boron
precursor, namely, 1-Ph-nido-1-CB8H11.29
from a cluster vertex (bound to CBBBBB or CBBBB faces)
to an exo-polyhedral site (bound to the platinum and by two
B-H F Mn bridges). In the 1H NMR spectrum, the protons
involved in these agostic-type interactions give rise to broad
resonances coincident at δ ca. -9.3, typical for such
hydrogens.4,30
Conclusion
The reactions of the mangana(tricarbonyl)carborane salt
1b reported herein, together with those described previously
for its rhenium analogue 1a,4,6 have revealed that a rich
chemistry is associated with subicosahedral, “half-sandwich”
metal monocarbollide cage frameworks. These new results
further exemplify the variety of novel compounds that can
be derived from monocarbollide complexes in general,3b as
opposed to their dicarbollide31 analogues. Of particular
interest in the present work is the unprecedented spontaneous
insertion of the exo-polyhedral platinum fragment into the
manganacarborane cluster in compound 6, providing the
novel dimetallacarboranes 7. Equally intriguing is the
conversion of 7b to 8, via extrusion of boron and manganese
vertexes, which completes the series whereby manganese and
platinum centers exchange exo- and endo-polyhedral sites.
Although it seems clear that this exchange proceeds via a
12-vertex dimetal intermediate, the details of the mechanism
and the reasons for this behavior are less clear. Our studies
of these and related systems, as well as our attempts to
identify other trace products in these reactions, are continu-
ing.
The exo-polyhedral {Mn(CO)3} unit in 8 is attached to
the platinacarborane surface via a Pt-Mn bond [Pt-Mn )
2.8088(9) Å] and by two B-H F Mn agostic-type interac-
tions involving two adjacent boron atoms [Mn‚‚‚B(3) )
2.220(6), Mn-H(3) ) 1.90(6); Mn‚‚‚B(7) ) 2.181(6), Mn-
H(7) ) 1.80(6) Å]. This provides a distinct contrast with
compound 6, from which a Pt-Mn bond is absent. We are
aware of only one other report of a metallaheteroborane
bearing an exo-polyhedral {Mn(CO)3} group, namely, a
monoanionic derivative obtained from compound 1a.4 A pair
of {Mn(CO)4} derivatives of {closo-3,1,2-RhC2B9} clusters
are also known.30 None of these, unfortunately, has been
structurally characterized.
Experimental Section
General Considerations. All reactions were carried out under
an atmosphere of dry, oxygen-free nitrogen using standard Schlenk
line techniques. Solvents were distilled from appropriate drying
agents under nitrogen prior to use. Petroleum ether refers to that
fraction of boiling point 40-60 °C. Chromatography columns
(typically ca. 15 cm in length and ca. 2 cm in diameter) were packed
with silica gel (Acros, 60-200 mesh). Celite pads used for filtration
were typically ca. 3 cm in depth and 2 cm in diameter. NMR spectra
were recorded at the following frequencies (MHz): 1H, 360.1; 13C,
90.6; 11B, 115.5; 31P, 145.8. The compounds [NEt4][6-Ph-nido-6-
Spectroscopic and other physical data characterizing
compound 8 are presented in Tables 1-3. In its 11B{1H}
NMR spectrum, eight resonances of unit integral are seen,
consistent with the absence of any symmetry in the solid-
state structure. Likewise, the 31P{1H} NMR spectrum shows
two separate resonances, each with 195Pt satellites, also
consistent with an asymmetric system. The 1H and 13C{1H}
NMR spectra exhibit signals in the appropriate positions for
the cage, phosphine and carbonyl ligands, of which the most
significant features are the lowering in chemical shifts of
the ipso carbon atom of the cluster-bound phenyl unit and
of the carbonyl groups. Of these, the former resonates at δ
139.9 in 8, compared to δ ca. 145-155 in all of compounds
1-7;4 it is unfortunate that the signal for the cage carbon
atom could not definitively be located as this would likely
also reveal some further information about the electronic
properties of the {PtCB8} cluster in compound 8. The
manganese-bound CO groups give a single broad peak at δ
208.7 in the 13C{1H} NMR spectrum, compared to δ ca.
220-225 in compounds 1b, 3a, and 5-7. The increased
shielding can be attributed to the {Mn(CO)3} center changing
34
CB9H11],32 [Mn(NCMe)3(CO)3][PF6],33 and [CuCl(PPh3)]4 were
prepared by literature methods; [NiCl2(dppe)] was formed from
NiCl2 and dppe in refluxing EtOH (15 min); and the complexes
[PdCl2(dppe)] and [PtCl2(dppe)] were obtained by addition of dppe
to a CH2Cl2 solution of [MCl2(NCPh)2] (M ) Pd, Pt).35 All other
reagents were used as received.
Synthesis of [N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-
MnCB9H9]. A THF (20 mL) solution of [NEt4][6-Ph-nido-6-
(31) Ellis, D. D.; Jelliss, P. A.; Stone, F. G. A. Organometallics 1999, 18,
4982. Ellis, D. D.; Jelliss, P. A.; Stone, F. G. A. J. Chem. Soc., Dalton
Trans. 2000, 2113. Ellis, D. D.; Jeffery, J. C.; Jelliss, P. A.; Kautz, J.
A.; Stone, F. G. A. Inorg. Chem. 2001, 40, 2041.
(32) Jel´ınek, T.; Thornton-Pett, M.; Kennedy, J. D. Collect. Czech. Chem.
Commun. 2002, 67, 1035. See also: Brellochs, B. In Contemporary
Boron Chemistry; Davidson, M. G., Hughes, A. K., Marder, T. B.,
Wade, K., Eds.; Royal Society of Chemistry: Cambridge, U.K., 2000;
p 212.
(28) Alcock, N. W.; Taylor, J. G.; Wallbridge, M. G. H. J. Chem. Soc.,
Chem. Commun. 1983, 1168.
(29) Carr, M. J.; Franken, A.; Kennedy, J. D. Dalton Trans. 2004, 2612.
(30) Jeffery, J. C.; Stone, F. G. A., Topalogˇlu, I. J. Organomet. Chem.
1993, 451, 205.
(33) Reiman, R. H.; Singleton, E. J. Chem. Soc., Dalton Trans. 1974, 808.
(34) Mann, F. G.; Purdie, D. J. Chem. Soc. 1935, 1549. Jardine, F. H.;
Rule, J.; Vohra, G. A. J. Chem. Soc. A 1970, 238.
(35) Anderson, G. K.; Lin, M. Inorg. Synth. 1990, 28, 61.
Inorganic Chemistry, Vol. 44, No. 8, 2005 2823

Du et al.
a
Table 4. Crystallographic Data for 5b·2CH2Cl2, 6·CH2Cl2, 7d·CH2Cl2, and 8·2CH2Cl2
b
5b‚2CH2Cl2
6‚CH2Cl2
7d‚CH2Cl2
8‚2CH2Cl2
formula
fw
C38H40B9Cl4MnO3P2Pd
1007.09
C37H40B9Cl2MnO3P2Pt
1012.85
C39H44B9Cl2MnO5P2Pt
1072.90
C38H41B8Cl4MnO3P2Pt
1085.96
a, Å
b, Å
c, Å
10.9749(3)
11.5671(3)
20.1699(5)
92.365(2)
95.300(2)
114.092(2)
2318.68(10)
1.442
10.571(2)
12.0680(19)
18.590(4)
103.014(17)
95.691(17)
113.966(17)
2062.5(7)
1.631
173(2)
3.937
7687
7257
10.3831(13)
11.7188(14)
18.555(2)
85.961(5)
78.853(5)
81.942(5)
2191.1(5)
1.626
110(2)
3.714
39671
11906
10.0647(11)
11.0280(7)
20.0776(18)
86.511(6)
77.386(9)
88.671(8)
2170.6(3)
1.662
173(2)
3.867
8527
7997
R, deg
â, deg
γ, deg
V, Å3
F
calcd, g cm-3
T, K
100(2)
µ(Mo KR), mm-1
reflns measured
indep reflns
Rint
8.388c
18178
7871
0.0471
0.1332, 0.0509
0.0284
0.0996, 0.0435
0.0719
0.0750, 0.0470
0.0167
0.1074, 0.0412
wR2(all data), R1d
a All crystals were triclinic, space group P1h, Z ) 2. b One CH2Cl2 solvate was refined without H atoms; the empirical formula and the values quoted for
the fw, Fcalcd, and µ reflect this. c µ(Cu KR). d wR2 ) {∑[w(Fo - Fc )2]/∑w(Fo )2}1/2 and R1 ) ∑||Fo| - |Fc||/∑|Fo|, with Fo > 4σ(Fo).
2
2
2
n
CB9H11] (0.411 g, 1.26 mmol) was cooled to -78 °C and BuLi
(1.0 mL, 2.5 M solution in hexanes, 2.50 mmol) was added. After
the mixture had warmed to ca. -40 °C, [Mn(NCMe)3(CO)3][PF6]
(0.511 g, 1.26 mmol) was added. The mixture was warmed to room
temperature and was stirred at this temperature for 3 h; [N(PPh3)2]Cl
(1.40 g, 2.44 mmol) was then added, and stirring was continued
overnight. A yellow solid precipitated that was isolated by filtration,
washed with ice-cold EtOH (20 mL) and dried in vacuo to give
[N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9] (1b) (0.92
g) as a dark yellow, microcrystalline solid. Residual EtOH was
removed by recrystallization from acetone/petroleum ether.
Synthesis of [1,6-{Cu(PPh3)}-1,7-{Cu(PPh3)}-6,7-(µ-H)2-1,1,1-
(CO)3-2-Ph-closo-1,2-MnCB9H7]. To a CH2Cl2 (20 mL) solution
of 1b (0.100 g, 0.10 mmol) was added [CuCl(PPh3)]4 (0.072 g,
0.05 mmol) and Tl[PF6] (0.070 g, 0.20 mmol), and the mixture
was stirred overnight. After filtration (Celite), solvent was removed
in vacuo, and the residue was applied to a chromatography column.
Elution with CH2Cl2/petroleum ether (3:2) removed a yellow band,
from which [1,6-{Cu(PPh3)}-1,7-{Cu(PPh3)}-6,7-(µ-H)2-1,1,1-
(CO)3-2-Ph-closo-1,2-MnCB9H7] (3a) (0.049 g) was isolated as a
yellow microcrystalline solid after removal of the solvent in vacuo.
Reactions of Compound 1b with [MCl2(dppe)] (M ) Ni, Pd,
Pt) in the Presence of Tl[PF6]. (i) Compound 1b (0.200 g, 0.20
mmol), [NiCl2(dppe)] (0.106 g, 0.20 mmol), and Tl[PF6] (0.140 g,
0.40 mmol) were stirred overnight in CH2Cl2 (30 mL). The reaction
mixture was filtered (Celite) and evaporated to dryness, and the
residue was applied to a chromatography column. A wine fraction
was eluted with CH2Cl2/petroleum ether (3:2), which, after removal
of the solvent in vacuo, yielded [1,3-{Ni(dppe)}-3-(µ-H)-1,1,1-
(CO)3-2-Ph-closo-1,2-MnCB9H8] (5a) (0.060 g) as dark burgundy
microcrystals.
removed a violet band, which, after evaporation in vacuo, gave
[3,6-{Pt(dppe)}-3,6-(µ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9-
H7] (6) (0.175 g) as dark purple microcrystals. Repeated column
chromatography of compound 6 always afforded a few milligrams
more of compound 8.
Synthesis of the Compounds [1-Ph-2,2,2-(CO)3-7-X-8,8-(dppe)-
hypercloso-8,2,1-PtMnCB9H8] [X ) OEt, H, OMe, O(CH2)2OH,
O(CH2)4OH, OCH2C≡CH]. (i) Compound 6 (0.020 g, 0.022
mmol) was dissolved in CH2Cl2 (30 mL), EtOH (0.05 mL) was
added, and the mixture was stirred overnight. After removal of the
solvent in vacuo, the residue was taken up in minimal CH2Cl2/
petroleum ether (1:1) and applied to a chromatography column.
Elution with CH2Cl2/petroleum ether (3:2) gave a single green
fraction, from which [1-Ph-2,2,2-(CO)3-7-OEt-8,8-(dppe)-hyper-
closo-8,2,1-PtMnCB9H8] (7a) (0.015 g) was isolated as dark green
microcrystals after removal of the solvent in vacuo.
(ii) Compound 6 (0.020 g, 0.022 mmol) was dissolved in
CH2Cl2 (30 mL), and the solution was stirred overnight. Slow
addition of the resulting dark green mixture to an excess (100 mL)
of petroleum ether precipitated essentially pure [1-Ph-2,2,2-(CO)3-
8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H9] (7b) (0.017 g), isolated
as a dark green powder. Attempted further purification by column
chromatography resulted in significant conversion to compound 8.
(iii) A solution of compound 6 (0.020 g, 0.022 mmol) in
CH2Cl2/MeOH (2:1, 15 mL) was stirred overnight. Workup as
above for compound 7a gave dark green [1-Ph-2,2,2-(CO)3-7-OMe-
8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H8] (7c) (0.015 g).
(iv) By a similar procedure, compound 6 (0.100 g, 0.11 mmol)
in CH2Cl2 (10 mL) treated with HO(CH2)2OH (0.3 mL) gave dark
green [1-Ph-2,2,2-(CO)3-7-{O(CH2)2OH}-8,8-(dppe)-hypercloso-
8,2,1-PtMnCB9H8] (7d) (0.052 g).
(ii) Similarly, the compound [1,3,6-{Pd(dppe)}-3,6-(µ-H)2-1,1,1-
(CO)3-2-Ph-closo-1,2-MnCB9H7] (5b) (0.099 g) was obtained as a
microcrystalline indigo solid following the reaction between 1b
(0.200 g, 0.20 mmol), [PdCl2(dppe)] (0.115 g, 0.20 mmol) and
Tl[PF6] (0.140 g, 0.40 mmol).
(iii) A mixture of 1b (0.300 g, 0.30 mmol), [PtCl2(dppe)] (0.199
g, 0.30 mmol), and Tl[PF6] (0.210 g, 0.60 mmol) in CH2Cl2 (30
mL) was stirred for 30 min, filtered (Celite), and then evaporated
to dryness in vacuo. Chromatography of the residue, eluting with
CH2Cl2/petroleum ether (2:3), gave first a broad orange-yellow
band, from which [3,6,7-{Mn(CO)3}-3,7-(µ-H)2-1-Ph-6,6-(dppe)-
closo-6,1-PtCB8H6] (8) (0.014 g) was obtained as an orange-red
powder. Further elution, using CH2Cl2/petroleum ether (3:2),
(v) Likewise, treatment of a CH2Cl2 (10 mL) solution of
compound 6 (0.100 g, 0.11 mmol) with HO(CH2)4OH (0.3 mL)
gave dark green [1-Ph-2,2,2-(CO)3-7-{O(CH2)4OH}-8,8-(dppe)-
hypercloso-8,2,1-PtMnCB9H8] (7e) (0.055 g).
(vi) Similarly, compound 6 (0.100 g, 0.11 mmol) in CH2Cl2 (10
mL) with HCtCCH2OH (0.3 mL) gave dark green [1-Ph-2,2,2-
(CO)3-7-{OCH2CtCH}-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9-
H8] (7f) (0.030 g).
Structure Determinations. Experimental data for compounds
5b, 6, 7d, and 8 are reported in Table 4. Diffracted intensities for
6 and 8 were collected at 173(2) K on an Enraf-Nonius CAD4
diffractometer using Mo KR X-radiation (λ ) 0.71073 Å). Data
were corrected for Lorentz and polarization effects, after which
2824 Inorganic Chemistry, Vol. 44, No. 8, 2005

Reactions of the [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2-
numerical absorption corrections based on the measurement of the
various crystal faces were applied.
positions were successfully refined; those in 5b and 7d were set
riding in calculated positions, apart from one of the hydrogen atoms
[H(6)] involved in the agostic-type B-H F Pd interactions in 5b,
which was positionally refined. All hydrogen atoms were refined
with fixed isotropic thermal parameters, calculated as Uiso(H) )
1.2Uiso(parent), except H(3) and H(6) in 5b, whose temperature
factors were freely refined.
A sphere of X-ray intensity data for 5b was collected at 100(2)
K on a Bruker SMART CCD area-detector diffractometer equipped
with a rotating anode source (Cu KR radiation, λ ) 1.54184 Å).
For several settings of æ, narrow data “frames” were collected for
0.3° increments of ω. Data for 7d were acquired at 110(2) K using
a Bruker-Nonius X8 Apex area-detector diffractometer (Mo KR
radiation). Several sets of data frames were collected at different θ
values for various initial values of φ and ω, each frame covering
a 0.5° increment of φ or ω. For the two data sets measured on
area-detector devices, the data frames were integrated using
SAINT;36 the substantial redundancy in data allowed empirical
absorption corrections (SADABS)36 to be applied on the basis of
multiple measurements of equivalent reflections.
Compounds 5b and 8 each cocrystallize with two molecules of
CH2Cl2 as solvate. One of these molecules in 5b and both molecules
in 8 were well-behaved and were treated as above. The other CH2-
Cl2 molecule in the asymmetric unit of 5b was disordered, with
the pair of Cl atoms located over two sites. For this molecule, the
occupancies of the two parts were refined and then fixed at the
ratio 60:40, and no hydrogen atoms were included.
Each molecule of 6 cocrystallizes with one molecule of CH2-
Cl2, as does each molecule of 7d. In the solvate in crystals of 6,
one Cl atom was well-behaved, whereas the other was disordered
over two sites. The two partial chlorines were assigned refining
complementary occupancies, which were in the approximate ratio
86:14 at convergence. In 7d, the pair of chlorides occupied two
different sites. Thus, the molecule was refined as two parts, with
only the carbon atom at a common site in each part. Refining
complementary occupancies were assigned to each part, and these
converged at the approximate ratio 75:25. For both of these solvates,
separate methylene hydrogens were included in association with
each part, and the solvate atoms were otherwise treated as described
above.
The structures were solved (SHELXS-97) via conventional direct
methodsswith the exception of 7d, which was solved using the
Patterson functionsand refined (SHELXL-97) by full-matrix least-
squares on all F 2 data using SHELXTL, version 5.03 or 6.10.36,37
All non-hydrogen atoms were assigned anisotropic displacement
parameters. The locations of the cage carbon atoms were verified
by examination of the appropriate internuclear distances and the
magnitudes of their isotropic thermal displacement parameters.
All of the hydrogen atoms in organic functions were set riding
on their parent atoms in calculated positions. The hydroxyl hydrogen
in 7d was located in difference maps, but upon being allowed
positional refinement, it tended to collapse toward the parent O
atom. Accordingly, this hydrogen was included riding on the oxygen
atom, using a “rotating group” refinement that maximized the
electron density at the calculated position (AFIX 147 card in
SHELXL37). This calculated position was noted to correspond very
closely to that initially obtained from difference maps and thus
afforded a satisfactory treatment of this H atom. Cluster BH
hydrogens in 6 and 8 were all located in difference maps, and their
Acknowledgment. We thank the Robert A. Welch
Foundation, the E.P.S.R.C., and the National Science Foun-
dation (M.R.I. Program, Grant CHE-0321214) for support.
Supporting Information Available: Full details of the crystal
structure analyses in CIF format. This material is available free of
charge via the Internet at http://pubs.acs.org.
(36) APEX 2, version 1.0-5, Bruker AXS: Madison, WI, 2003.
(37) SHELXTL, versions 5.03 and 6.10; Bruker AXS: Madison, WI, 1995
and 2000.
IC048345W
Inorganic Chemistry, Vol. 44, No. 8, 2005 2825