Meta and para metallation of EPh4+ (E=P, As) and N(PPh3)2+ by the dinuclear acylanion [Re2(μ-H)(μ-PCy2)(CO)7ax-(C(Ph)O)] -. Formation of zwitterionic cluster complexes Re2(μ-H)(μ-PCy2)(CO)7(x-C 6H4EPh3) (E=P, As; X=m, p).

Article abstract of DOI:10.1016/S0022-328X(99)00077-7

On treating the dirhenium salt Li[Re₂(μ-H)(μ-PCy₂)(CO)₇ax-(C(Ph)O)] (Li(1)) with EPh₄Cl (E=P, As) or N(PPh₃)₂Cl, respectively, in THF at room temperature, metathesis of the cations occurs to give the intermediates EPh₄[Re₂(μ-H)(μ-PCy₂)(CO) ₇ax-(C(Ph)O)] (EPh₄(1)) or N(PPh₃)₂[Re₂(μ-H)(μ-PCy ₂)(CO)₇ax-(C(Ph)O)] (N(PPh₃)₂(1)). PPh₄(1) was isolated and its X-ray structure was determined. Upon stirring these intermediates in THF solution at 20°C for 2 days, benzaldehyde (PhCHO) is eliminated and the para and meta metallated products Re₂(μ-H)(μ-PCy₂)(CO)₇(x-C ₆H₄EPh₃) (E=P, x=m: 2a, x=p: 2b; As, x=m: 3a, x=p: 3b) and Re₂(μ-H)(μ-PCy₂)(CO)₇(x-C ₆H₄PPh₂NPPh₃) (x=m: 4a, x=p: 4b) are formed by C-H oxidative addition. Heating to 45°C shortens the reaction time to 4 h. The products are zwitterionic, consisting of a negatively charged dirhenium unit and a positively charged phosphonium, arsonium or bistriphenylphosphine iminium ligand, respectively, bound to one of the rhenium atoms. In each case, the m- and p-isomers could be separated by PLC. Moreover, 2b was crystallized from a benzene solution and its molecular structure was confirmed by X-ray analysis. The above sequence of reactions was repeated with d₂₀-PPh₄Br. It reacts completely analogous to give the deuterated products Re₂(μ-D)(μ-PCy₂)(CO)₇(x-C ₆D₄(d₁₅-EPh₃)) (E=P, x=m: d₂₀-2a, x=p: d₂₀-2b). Hence, the μ-H and μ-D ligands, respectively, of the new compounds originate from the corresponding aromatic cation. The reaction of Li(1) with SbPh₄Br proceeds completely different. PhCHO is eliminated again, but no metallated products were found. Only the decomposition product Re₂(μ-Br)(μ-PCy₂)(CO)₇(eq-SbPh ₃) (5) was isolated in 19% yield.

Full text of DOI:10.1016/S0022-328X(99)00077-7

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 582 (1999) 345–351
Meta and para metallation of EPh4+ (E=P, As) and N(PPh3)2+
by the dinuclear acylanion [Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)]−.
Formation of zwitterionic cluster complexes
Re2(m-H)(m-PCy2)(CO)7(x-C6H4EPh3) (E=P, As; x=m, p) and
Re2(m-H)(m-PCy2)(CO)7(x-C6H4PPh2NPPh3)
Hans Egold *, Markus Schraa, Ulrich Flo¨rke
Anorganische und Analytische Chemie der Uni6ersita¨t Paderborn, Fachbereich 13, Chemie und Chemietechnik, Warburger Straße 100,
D-33098 Paderborn, Germany
Received 2 November 1998
Abstract
On treating the dirhenium salt Li[Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)] (Li(1)) with EPh4Cl (E=P, As) or N(PPh3)2Cl,
respectively, in THF at room temperature, metathesis of the cations occurs to give the intermediates EPh4[Re2(m-H)(m-
PCy2)(CO)7ax-(C(Ph)O)] (EPh4(1)) or N(PPh3)2[Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)] (N(PPh3)2(1)). PPh4(1) was isolated and its
X-ray structure was determined. Upon stirring these intermediates in THF solution at 20°C for 2 days, benzaldehyde (PhCHO)
is eliminated and the para and meta metallated products Re2(m-H)(m-PCy2)(CO)7(x-C6H4EPh3) (E=P, x=m: 2a, x=p: 2b; As,
x=m: 3a, x=p: 3b) and Re2(m-H)(m-PCy2)(CO)7(x-C6H4PPh2NPPh3) (x=m: 4a, x=p: 4b) are formed by CꢀH oxidative
addition. Heating to 45°C shortens the reaction time to 4 h. The products are zwitterionic, consisting of a negatively charged
dirhenium unit and a positively charged phosphonium, arsonium or bistriphenylphosphine iminium ligand, respectively, bound to
one of the rhenium atoms. In each case, the m- and p-isomers could be separated by PLC. Moreover, 2b was crystallized from
a benzene solution and its molecular structure was confirmed by X-ray analysis. The above sequence of reactions was repeated
with d20-PPh4Br. It reacts completely analogous to give the deuterated products Re2(m-D)(m-PCy2)(CO)7(x-C6D4(d15-EPh3))
(E=P, x=m: d20-2a, x=p: d20-2b). Hence, the m-H and m-D ligands, respectively, of the new compounds originate from the
corresponding aromatic cation. The reaction of Li(1) with SbPh4Br proceeds completely different. PhCHO is eliminated again, but
no metallated products were found. Only the decomposition product Re2(m-Br)(m-PCy2)(CO)7(eq-SbPh3) (5) was isolated in 19%
yield. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Para metallation; Meta metallation; Zwitterionic cluster complex; Rhenium carbonyl complex
1. Introduction
salt Li[Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)] (Li(1)) is
formed selectively in nearly quantitative yield. It reacts
with two equivalents of XAuPPh3 (X=Cl, Br, I) under
elimination of benzaldehyde (PhCHO) to give the
metallatetrahedranes Re2(AuPPh3)2(m-PCy2)(CO)7X [5].
On treating Li(1) with carboxylic acids RCO2H and
heating to 60°C, PhCHO is eliminated again and the
salts Li[Re2(m-H)(m-PCy2)(CO)7ax-(h1-OC(R)O)] are
formed. The formyl proton of PhCHO originates pre-
dominantly from the hydrido bridge of Li(1) [6]. In
order to find substrates other than XAuPPh3 or
RCO2H, which could be added to the dirhenium unit
Hydrido phosphido bridged cluster complexes are
well known in organometallic chemistry. Especially
compounds of the type M3(m-H)(m-PR2)(CO)10 (M=
Ru, Os; R=organic residue) [1,2] and M2(m-H)(m-
PR2)(CO)8 (M=Mn, Re) [3,4] have been intensively
investigated. The latest studies on Re2(m-H)(m-
PCy2)(CO)8 have been focused on its reactivity towards
PhLi in THF solution at −100°C. In this reaction, the
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00077-7

346
H. Egold et al. / Journal of Organometallic Chemistry 582 (1999) 345–351
after elimination of PhCHO, we decided to isolate the
salts EPh4[Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)] (E=P,
As) or N(PPh3)2[Re2(m-H)(m-PCy2)(CO)7ax-(C(Ph)O)],
respectively.
In this paper we wish to report the surprising reac-
tion of Li(1) with EPh4Cl and N(PPh3)2Cl, respectively,
resulting in the formation of novel meta and para
metallated, zwitterionic dirhenium cluster complexes
under mild reaction conditions. Such meta and para
metallation reactions are rare, only one example of para
metallation by a transition metal is present in the
literature. In that case, heating of the solid (N-
Mepy)2PtCl6 (py=pyridine) to 180°C gave (N-
Mepy)[Cl5Pt(C5H4NMe)] [7]. Additionally, our work
provides information on the mechanism of the reaction,
which was elucidated by the reaction of Li(1) with
d20-PPh4Br and on the decomposition reaction of Li(1)
with SbPh4Br.
Fig. 1. Molecular structure of (1)−. Hydrogen atoms omitted.
of Li(1) and PPh4Cl in THF. Hence, the metathesis
reaction proceeds quantitatively within a few minutes.
PPh4(1) was isolated in 86% yield and its molecular
structure was determined by a single-crystal X-ray anal-
ysis (Fig. 1). However, when the above mentioned
mixture is stirred at room temperature for 2 days the
formation of benzaldehyde (PhCHO) is observed by IR
measurements. This new reaction is followed easily by
31P-NMR and IR measurements. Within 2 days, the
resonances of PPh4(1) disappeared completely. Instead
signals of 2a (l(m-P): 59.2, l(P+): 22.8) and 2b (l(m-P):
58.2, l(P+): 23.6) appeared. In the same period of time
the w(CO) band of the acyl ligand (1545 cm−1) of
PPh4(1) disappeared and a large w(CO) band of Ph-
CHO (1704 cm−1) is formed. Compounds 2a and 2b
(Scheme 1) were isolated by PLC as air-stable, amor-
phous, colorless solids in 44% (2a) and 8% (2b) yield,
respectively. Heating to 45°C shortens the reaction time
to 4 h. The isomer distribution as measured by 1H-
NMR was determined to be 85% 2a and 15% 2b.
Compounds 2a and 2b were characterized by w(CO) IR,
1H-, 31P-NMR spectra and elemental analysis. Also, the
molecular structure of 2b was determined by a single-
crystal X-ray analysis (Fig. 2). The comparison of the
spectroscopic data of 2a and 2b allows the identification
of 2a. Both compounds show a characteristical w(CO)
IR spectrum consisting of seven absorption bands.
Compared with the w(CO) IR spectrum of PPh4(1), the
bands of both products are almost unshifted. There-
fore, it is reasonable to assume that a negative charge
remains at the dirhenium core and consequently a
positive charge at the phosphorous of the phosphonium
ligand (zwitterionic structure). This hypothesis is also
supported by the X-ray data of 2b (cf. Section 3) and
the 31P-NMR data of 2a and 2b. The 31P-NMR signals
of the phosphonium ligands in CDCl3 are at 22.8 ppm
for 2a and 23.6 ppm for 2b. In comparison, the signal
2. Results and discussion
2.1. Synthesis and reaction mechanism
On treating Li(1) (l(m-P): 63.4) with 1.5 equivalents
PPh4Cl in THF solution at room temperature a
metathesis reaction occurs to give PPh4(1) (l(m-P): 72.0,
l(PPh4+): 23.0) and LiCl (Scheme 1, step (i)). The
w(CO) IR and 31P-NMR spectra of PPh4(1) [5] in THF
cannot be distinguished from spectra of a 1:1 mixture
1
Scheme 1. Proposed reaction mechanism.
of PPh4Cl in CDCl3 is at 23.8 ppm. The H spectra of

H. Egold et al. / Journal of Organometallic Chemistry 582 (1999) 345–351
347
2a and 2b exhibit doublets at −13.23 or −13.01,
respectively, confirming the existence of a m-bound H
In order to find out if this kind of reaction is
transferable to other aromatic cations and to get a
better understanding of the isomer distribution, the
reaction was repeated using AsPh4Cl·H2O, SbPh4Br
and N(PPh3)2Cl, respectively. In the case of
AsPh4Cl·H2O and N(PPh3)2Cl, the expected products
Re2(m-H)(m-PCy2)(CO)7(x-C6H4AsPh3) (x=m: 3a, x=
p: 3b; yield: 23% 3a, 5% 3b; isomer distribution: 82%
3a/18% 3b) and Re2(m-H)(m-PCy2)(CO)7(x-C6H4PPh2-
NPPh3) (x=m: 4a, x=p: 4b; yield: 20% 4a, 17% 4b;
isomer distribution: 54% 4a/46% 4b) were found. The
yields of these products when compared with 2a and 2b
are distinctly lower. This cannot be attributed to side
reactions. 31P-NMR spectra of the reaction mixtures
revealed almost complete formation of 2a, 2b and 3a,
3b and 4a, 4b, respectively. Hence, the isomers decom-
pose during PLC separation. Interestingly, the isomer
distribution is not affected by the above mentioned
decomposition. The w(CO) IR spectra of all new com-
pounds show seven absorption bands due to the low
symmetry of the molecules (point group C1). The chem-
ical shift of the m-P ligand is almost unaffected by the
different cationic ligands. It varies only slightly from
57.9 ppm for d20-2b to 59.4 ppm for 3a. The 31P-NMR
spectrum of 4a and 4b, respectively, shows three sig-
nals. The signal at low field belongs to the m-P ligand.
1
ligand. The main difference between both H spectra is
the substitution pattern of the phenyl ring bound to
rhenium. In 2b, two double doublets are present confir-
ming para substitution. In 2a, four groups of signals are
found proving meta substitution.
In Scheme 1 the proposed mechanism of the forma-
tion of 2a and 2b is illustrated. First, the above men-
tioned metathesis reaction takes place (step (i)) resulting
in the formation of PPh4(1). This is decisive for the next
step as Li(1) itself eliminates PhCHO only in small
amounts on heating to 60°C. But now (step (ii)), Ph-
CHO is eliminated easily, possibly due to formation of
a contact ion pair. In the hypothetical transition state,
the valence electron deficit of the dirhenium core is
compensated by a h2-bound phenyl ring of PPh4+. This
bonding pattern is well known for organometallic com-
pounds [8]. The transition state is electronically similar
to the anionic cluster complexes [M2(m-PR2)(CO)8]−
(M=Mn, Re; R=organic residue) [9]. Finally, the m-
(step (iii)) or p- (step (iv)) CꢀH bond, respectively, is
cleaved affording a new m-H ligand and an axial (with
respect to the plain Reꢀ(m-P)ꢀRe) phosphonium ligand.
The origin of the m-H ligand was established by the
reaction of Li(1) with d20-PPh4Br. The products of this
reaction, d20-2a and d20-2b, showed w(CO) IR and
31P-NMR spectra almost identical to 2a and 2b. The
1H-NMR spectra, however, showed no resonances in
the aromatics region and no resonances at high field.
Accordingly, the presence of a d19-phosphonium ligand
and a m-D ligand is indicated. Hence, the m-H ligand in
2a and 2b originates from a phenyl ring of PPh4+.
2
The other two resonances are doublets with a JPP
coupling constant of 6 Hz. They must be assigned to
the phosphorous atoms of the iminium ligand.
The reaction of Li(1) with SbPh4Br yielded none of
the expected isomers. 31P-NMR spectra of the reaction
mixture showed no shift of the m-P signal of Li(1) after
addition of SbPh4Br. Hence, no metathesis reaction
takes place and there is no reaction at room tempera-
ture. On heating to 60°C PhCHO is formed again and
the color of the solution turns brown. 31P-NMR spectra
of these solutions show at least ten different signals and
indicate a decomposition reaction. The novel dirhenium
complex Re2(m-Br)(m-PCy2)(CO)7(eq-SbPh3)
5
was
found to be the only isolable product (19% yield). Its
molecular structure was determined by a single-crystal
X-ray analysis [10]. These experimental results suggest
that Li+ in Li(1) is not exchanged for SbPh4+. Conse-
quently, higher reaction temperatures are needed as
PhCHO is now eliminated from Li(1). The cluster
complex formed in this way is labile due to its valence
electron deficit and decomposes under these conditions
rapidly. The formation of 5 is a consequence of the
reactivity of SbPh4+. The latter cation, in contrast to
PPh4+ and AsPh4+, is known to be a phenylating agent
[11]. Therefore, we suppose that it partially breaks
down into ‘Ph+’ and SbPh3. Finally, 5 is formed by a
dirhenium fragment of the above mentioned decompo-
sition reaction, the bromide of SbPh4Br and SbPh3.
Fig. 2. Molecular structure of 2b. Cyclohexyl and phenyl hydrogen
atoms omitted.

348
H. Egold et al. / Journal of Organometallic Chemistry 582 (1999) 345–351
Table 1
2.2. Isomer distribution
Crystal data and refinement details
The isomer distribution 2a/2b, 3a/3b and 4a/4b, re-
spectively, is constant during the entire reaction as
proved by 31P-NMR spectra recorded each 30 min at
45°C. As expected there is almost no change in the
isomer distribution of 2a/2b (p/m=1/5.5) compared
with 3a/3b (p/m=1/4.6). The m-isomer is always fa-
vored to the sterically less hindered p-isomer. But in
case of the extremely bulky N(PPh3)2+, the ratio is
shifted to p/m=1/1.2. These facts are best explained
in terms of electronic and steric arguments. Starting
from the transition state (Scheme 1) the electrophilic
Re is binding faster to the m-C atom than to the p-C
atom as the m-C atom has the lowest positive partial
charge of the aromatic ring. In case of very bulky
cations the rate of formation of the m-product de-
creases due to increasing sterical hindrance. The rate
of formation of the p-product, however, is less af-
fected by sterical hindrance.
Compound
Formula
PPh4(1)
2b·benzene
C50H48O8P2Re2
C43H42O7P2Re2,
C6H6
1183.2
Triclinic
P1
11.092(3)
14.363(3)
15.538(5)
99.90(2)
96.36(2)
92.34(2)
2391.0(11)
2
Mw
1211.2
Monoclinic
P21/c
11.389(2)
14.051(2)
30.664(5)
Crystal system
Space group
,
a (A)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
100.31(1)
3
,
V (A )
Z
4827.8(13)
4
1.666
5.127
2368
Dcalc (g cm−3
)
1.643
5.173
1156
v (mm−1
F(000)
)
Diffractometer
Siemens R3m; graphite monochromator, Mo–
Ka radiation
ꢀ, 452q555°
Scan type
R1, wR2 (all
data)
7.98, 23.41
4.80, 10.85
2.3. Conclusion
The salt Li(1) has proven to be extremely reactive
towards aromatic cations like PPh4+. The resulting
zwitterionic cluster complexes are very unusual and
deserve further investigations regarding their reactiv-
ity. Moreover, the reaction of N(PPh3)2+ shows that
Li(1) after release of PhCHO is able to metallate very
different aromatic cations. Therefore, we are currently
studying the reaction of Li(1) with other aromatic
cations. First results of these reactions with pyri-
dinium cations prove the transferability of the metal-
lation reaction to heteroaromatic substrates.
ing the PhCO ligand. The same bonding geometries
are valid for the complex Li(1), which has been de-
scribed earlier [5]. The position of the m-H atom
could not be determined, but the typical arrangement
of the equatorial CO groups 2 and 6 with ReꢀReꢀC
opening angles of 120.0(6)° and 113.7(4)°, respec-
tively, clearly indicate its presence [12a,c,d]. In the
anion [Re2(m-PPh2)(CO)8]− without this sterically de-
manding m-H ligand, the corresponding angles
ReꢀReꢀC are only 100° [4b].
3. Structural descriptions
2b: This structure is closely related to that of (1)−.
The main difference is the substitution of the PhCO
group in (1)− versus a likewise axially coordinated
phosphonium ligand, which is attached to the Re(1)
atom through the para-C atom of one phenyl group.
According to a search in the Cambridge data base
[13] this is the first transition metal compound ex-
hibiting this bonding pattern. The resulting ReꢀC(44)
PPh4(1) belongs to a well known family of hydrido-
phosphido-bridged dinuclear rhenium complexes
Re2(m-H)(m-PRR%)(CO)8 with
a metal–metal bond
[12]. In (1)− each Re atom has a distorted octahedral
coordination sphere from both the bridging H and P
atom and terminal four carbonyl groups at Re(2) and
three CO and one PhCO group at Re(1), respectively.
These terminal ligands show an almost eclipsed ar-
rangement at the Re centers, the axially attached
PhCO ligand has a ReꢀC(4) bond length of 2.21(2)
,
single bond length is 2.235(8) A and, consistent with
this substitution, both ReꢀP bond lengths show the
same differences as for (1)− with Re(2)ꢀP of 2.469(2)
,
,
A. The ReꢀRe bond length of 3.166(1) A compares
well with those from the above mentioned unsubsti-
tuted octacarbonyl complexes, where the distances
,
and Re(1)ꢀP of 2.442(2) A. The ReꢀRe bond length
−
,
of 3.1637(8) A, which is the same as that of (1) , is
,
elongated by ca. 0.021 A compared with that of the
,
range from 3.132 to 3.165(1) A. In these complexes
both ReꢀP bond lengths are equal, whereas (1)−
shows a different bonding pattern. Here, the Re(2)ꢀP
unsubstituted complex Re2(m-H)(m-PCy2)(CO)8 [12a].
The position of the m-H atom was determined from
difference Fourier map and refined (see Tables 1 and
2).
,
distance of 2.469(4) A is significantly longer than the
,
Re(1)ꢀP bond of 2.444(4) A, the latter Re atom bear-

H. Egold et al. / Journal of Organometallic Chemistry 582 (1999) 345–351
349
4. Experimental
of PPh4Cl (106 mg), d20-PPh4Br (112 mg),
AsPh4Cl(H2O (124 mg) or N(PPh3)2Cl (163 mg), respec-
tively, were added. The latter salts were not completely
dissolved. The resulting suspension was heated to 45°C
for 4 h. The formation of 2a–b, d20–2a–b, 3a–b, 4a–b,
was controlled by 31P-NMR and was found to be
almost quantitative. Accompanying w(CO) IR spectra
confirmed the release of PhCHO. The resulting suspen-
sions were concentrated in vacuo to 1 ml. Subsequently,
the m- and p-isomers were separated by PLC using the
following solvent mixtures: 2a/2b and d20-2a/d20-2b,
dichloromethane:n-hexane=1:1.5; 3a/3b, dichlorome-
thane:n-hexane=1:1.25; 4a/4b, dichloromethane:n-hex-
ane=1:1. After evaporation the amorphous, colorless
products were obtained in the following yields: 2a, 44%
(92 mg); 2b, 8% (17 mg); d20-2a 40% (85 mg); d20-2b, 7%
(15 mg); 3a, 23% (50 mg); 3b, 5% (10 mg); 4a, 20% (49
mg); 4b, 17% (42 mg).
4.1. General conditions
All reactions were performed with standard Schlenk
techniques in solvents free of oxygen which were dried
according to literature methods, distilled and stored
under argon atmosphere. PLC was carried out on glass
plates (20×20 cm2) coated with a mixture of gypsum
and silica gel (Merck 60 PF254, 1 mm thick).
4.1.1. Instrumentation
The reaction products were characterized by w(CO)
FTIR spectroscopy (Nicolet P510, CaF2 optics), 1H-
and 31P-NMR spectroscopy (Bruker AMX 300).
4.1.2. Starting materials
PPh4Cl, AsPh4Cl·H2O and PCl3 were purchased from
Fluka. N(PPh3)2Cl and SbPh4Br were obtained from
Aldrich. d5-Bromobenzene (99.5% d) was purchased
from Deutero GMBH. All reagents were laboratory
grade and used as received. Li[Re2(m-H)(m-
PCy2)(CO)7ax-(C(Ph)O)] and PPh4[Re2(m-H)(m-PCy2)-
(CO)7ax-(C(Ph)O)] [5] were prepared according to the
literature procedure. d15-PPh3 was prepared from d5-
PhMgBr and PCl3 in diethyl ether. It was subsequently
phenylated with d5-PhBr according to the method of
Horner [14] to give d20-PPh4Br.
4.3. Reaction of Li[Re2(v-H)(v-PCy2)(CO)7ax-(C(Ph)-
O)] with SbPh4Br
A yellow solution of 0.189 mmol Li[Re2(m-H)(m-
PCy2)(CO)7ax-(C(Ph)O)] in 10 ml THF was heated with
1.5 equivalents of SbPh4Br (145 mg) to 60°C for 5 h.
Within the first hour, the color of the suspension turned
brown. Accompanying 31P-NMR spectra showed at
least ten new signals. After cooling to room tempera-
ture the volatiles were removed in vacuo and the brown
4.2. Preparation of Re2(v-H)(v-PCy2)(CO)7(x-C6H4-
EPh3) (E=P, x=m: 2a, x=p: 2b; As, x=m: 3a,
x=p: 3b) and Re2(v-H)(v-PCy2)(CO)7(x-C6H4PPh2-
NPPh3) (x=m: 4a, x=p: 4b)
residue
was
separated
by
PLC
with
a
dichloromethane:n-hexane (1:2) solvent mixture. This
yielded in order of elution: PhCHO and 5 (19%, 44
mg).
To a yellow solution of 0.189 mmol Li[Re2(m-H)(m-
4.4. Spectroscopic data
PCy2)(CO)7ax-(C(Ph)O)] in 10 ml THF 1.5 equivalents
1
l values H-NMR spectra (CDCl3, standard TMS):
2a, −13.2 (d, 2JPH=7.6 Hz, 1H, m-H); 0.8–2.3 (m,
3
3
22H, Cy); 6.8 (dd, JPH=13.2 Hz, JHH=7.6 Hz, 1H,
Re(C6H4)-H4); 7.0 (dt, 3JHH=7.4 Hz, 4JPH=4.6 Hz,
1H, Re(C6H4)-H5); 7.5–7.9 (m, 15H, Ph); 8.1 (d,
3JPH=13.2 Hz, 1H, H2); 8.2 (d, 3JHH=7.1 Hz, 1H,
Table 2
,
Selected bond lengths (A) and angles (°)
For 1−
For 2b
Re(C6H4)-H6). 2b, −13.0 (d, JPH=7.6 Hz, 1H, m-H);
2
Bond lengths
3
3
0.8–2.3 (m, 22H, Cy); 6.7 (dd, JPH=13.2 Hz, JHH
=
Re(1)ꢀRe(2)
3.1667(9)
3.1637(8)
7.6 Hz, 2H, Re(C6H4)-H3); 7.2–7.8 (m, 15H, Ph); 8.2
3
4
Re(1)ꢀP(1)
Re(2)ꢀP(1)
Re(1)ꢀC(4)
C(4)ꢀO(4)
C(4)ꢀC(31)
2.444(4)
2.469(4)
2.21(2)
1.23(2)
1.54(2)
2.442(2)
2.469(2)
2.235(8)
(dd, JHH=7.6 Hz, JPH=5.1 Hz, 2H, Re(C6H4)-H2).
d20-2a, 0.8–2.34 (m, 22H, Cy). d20-2b, 0.78–2.32 (m,
22H, Cy). 3a, −13.19 (d, 2JPH=7.4 Hz, 1H, m-H);
Re(1)ꢀC(44)
3
0.82–2.26 (m, 22H, Cy); 6.76 (d, JHH=7.8 Hz, 1H,
Re(C6H4)-H4); 6.98 (t, JHH=7.5 Hz, 1H, Re(C6H4)-
3
Bond angles
H5); 7.55–7.91 (m, 15H, Ph); 8.04 (s, 1H, Re(C6H4)-
H2); 8.15 (d, 3JHH=7.3 Hz, 1H, Re(C6H4)-H6). 3b,
Re(1)ꢀP(1)ꢀRe(2)
P(1)ꢀRe(1)ꢀRe(2)
P(1)ꢀRe(2)ꢀRe(1)
Re(1)ꢀRe(2)ꢀC(6) 113.7(4)
Re(2)ꢀRe(1)ꢀC(2) 120.0(6)
80.27(11)
50.21(9)
49.52(9)
80.22(7)
50.26(5)
49.52(5)
116.0(2)
117.5(2)
2
−13.0 (d, JPH=7.7 Hz, 1H, m-H); 0.85–2.3 (m, 22H,
Cy); 6.67 (d, JHH=8.1 Hz, 2H, Re(C6H4)-H3); 7.5–7.8
3
Re(1)ꢀRe(2)ꢀC(4)
Re(2)ꢀRe(1)ꢀC(6)
3
(m, 15H, Ph); 8.22 (d, JHH=7.9 Hz, 2H, Re(C6H4)-
2
H2). 4a, −13.18 (d, JPH=7.5 Hz, 1H, m-H); 0.9–2.4

350
H. Egold et al. / Journal of Organometallic Chemistry 582 (1999) 345–351
(m, 22H, Cy); 6.63–6.68 (m, 2H, Re(C6H4)-H4 and H5);
refined anisotropically; cyclohexyl group C21–C26 was
found disordered over two sites and refined with a split
model with half occupation of C23–C26 each and full
occupation for C21 and C22; hydrogen atoms were
refined at idealized positions with riding model, the m-H
position was not determined.
7.35–7.9 (m, 25H, Ph); 7.92(d, 3JHH=5.0 Hz, 1H,
3
Re(C6H4)-H6); 8.0 (d, JPH=14.1 Hz, 1H, Re(C6H4)-
2
H2). 4b, −13.04 (d, JPH=7.8 Hz, 1H, m-H); 0.9–2.3
3
3
(m, 22H, Cy); 6.42 (dd, JPH=13.9, JHH=7.9 Hz, 2H,
Re(C6H4)3-H3); 7.3–7.7 (m, 25H, Ph); 7.85 (dd, JHH
=
3
7.6, JPH=4.7 Hz, 2H, Re(C6H4)-H2). 5, 0.8–2.3 (m,
2b. A colorless crystal, size 0.36×0.31×0.09 mm3,
was used for data collection as before. Lattice parame-
ters were refined from 25 reflections 1452q525°.
10 697 intensities collected −145h514, −185k5
18, 05l519; standards and corrections as before,
4
22H, Cy), 7.1–7.4 (m, 15H, Ph).
l values 31P-NMR spectra (CDCl3, standard 85%
H3PO4): 2a, 22.8 (s, 1P, P+); 59.2 (s, 1P, m-P). 2b, 23.6
(s, 1P, P+); 58.2 (s, 1P, m-P). d20-2a, 22.6 (s, 1P, P+);
58.8 (s, 1P, m-P). d20-2b, 23.3 (s, 1P, P+); 57.9 (s, 1P,
m-P). 3a, 59.4 (s, 1P, m-P). 3b, 58.5 (s, 1P, m-P). 4a, 19.4
min/max transmission 0.39/0.70, after merging (Rint
=
0.033) 10 293 unique intensities. Structure solution and
refinement as before, 530 parameters, hydrogen atoms
as before, the m-H position was determined from DF-
map and refined. Two independent half benzene solvent
molecules per asymmetric unit.
2
2
(d, JPP=6 Hz, 1P, PPh2); 23.5 (d, JPP=6 Hz, 1P,
2
PPh3); 59.0 (s, 1P, m-P). 4b, 20.1 (d, JPP=6 Hz, 1P,
2
PPh2); 24.1 (d, JPP=6 Hz, 1P, PPh3); 58.6 (s, 1P, m-P).
5, −76.5 (s, 1P, m-P).
w(CO) IR data in THF (cm−1): 2a, 2076 m, 1987 vs,
1975 m, 1962 m, 1927 vs, 1889 vs, 1871 vs. 2b, 2076 m,
1987 vs, 1975 m, 1962 m, 1927 vs, 1889 vs, 1871 vs.
d20-2a, 2075 s, 1986 s, 1975 sh, 1957 m, 1925 s, 1886 vs,
1871 vs. d20-2b, 2075 m, 1986 s, 1975 sh, 1961 m, 1927
vs, 1890 vs, 1871 vs. 3a, 2076 s, 1987 s, 1975 sh, 1962
m, 1927 vs, 1889 vs, 1871 vs. 3b, 2076 s, 1987 s, 1975
sh, 1962 m, 1927 vs, 1891 vs, 1871 vs. 4a, 2076 m, 1985
s, 1973 sh, 1964 m, 1925 vs, 1885 vs, 1869 vs. 4b, 2074
m, 1987 m, 1975 sh, 1962 m, 1925 vs, 1887 vs, 1870 vs.
5, 2094 m, 2067 w, 2038 w, 2017 sh, 1996 vs, 1936 vs,
1898 vs.
For both structures SHELXTL V5 [15] was used for
structure solution and refinement.
5. Supplementary material
Crystallographic data (excluding structure factors)
for the structural analysis have been deposited with the
Cambridge Crystallographic Data Centre, CCDC-
104497 for PPh4(1) and CCDC-104498 for 2b. Copies
of this information can be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (Fax: +44-1223-366-033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
Elemental analysis: 2a, C43H42O7P2Re2 (Mr=
1105.16), C 46.80 (calc. 46.73); H 3.77 (3.83). 2b,
C43H42O7P2Re2 (Mr=1105.16), C 46.91 (46.73); H 3.71
(3.83). 3a, C43H42AsO7PRe2 (Mr=1149.11), C 45.10
(44.95); H 3.77 (3.68). 3b, C43H42AsO7PRe2 (Mr=
References
1149.11),
C
45.12 (44.95);
H
3.75 (3.68). 4a,
C55H52NO7P3Re2 (Mr=1304.36), C 50.66 (50.64); H
4.19 (4.02); N 1.12 (1.07). 4b, C55H52NO7P3Re2 (Mr=
1304.36), C 50.61 (50.64); H 4.08 (4.02); N 1.01 (1.07).
5, C37H37BrO7PSbRe2 (Mr 1198.74), C 36.98 (37.29); H
3.02 (3.11).
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PPH4. An orange-yellow crystal, size 0.60×0.35×
0.16 mm3, was used for data collection at T=293 K.
Lattice parameters were refined from 34 reflections
1552q540°. A total of 11 152 intensities were col-
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absorption correction via „-scans, min/max transmis-
sion 0.44/0.99, after merging (Rint=0.043) 10 959
unique intensities. The structure was solved by direct
and conventional Fourier methods, full-matrix least-
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but H-atoms and disordered cyclohexyl-C-atoms were

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.