About the reaction of BeCl2 with the carbodiphosphorane addition compound O2C←C(PPh3)2 and its hydrolysis product Ph3PCHP(O)Ph2

Article abstract of DOI:10.1002/zaac.201100293

Abstract. Reaction of BeCl₂ and (PPh₄)[Be ₂Cl₆] with Ph₃PCHP(O)Ph₂ (2) and of BeCl₂ with O₂C←C(PPh₃)₂ (3) were studied under various conditions. Whereas the addition compound of 2 with BeCl₂ could only traced by ³¹P NMR spectroscopy the molecular structure of the O-addition compound [Ph₃PCH ₂P(OBeCl₃)Ph₂]·0.75CH₂Cl ₂ (5) from 2 and (PPh₄)[Be₂Cl₆] could be performed. From 3 and BeCl₂ in dichloromethane crystals of (H₂C{PPh₃}₂)[BeCl₄] (6) and (H ₂C{PPh₃}₂)Cl₂·CH ₂Cl₂ (7) separated. The cluster [Be₆(OH) ₆Cl₅(O₂C₂{PPh₃} ₂)₃]Cl(8) formed upon unintentionally admitting some humidity to the initial reaction mixture. In 8 each of the bidentate ligands 3 bridges two different beryllium atoms via the oxygen atoms. All compounds are characterized by X-ray diffraction analyses. Copyright

Full text of DOI:10.1002/zaac.201100293

ARTICLE
DOI: 10.1002/zaac.201100293
About the Reaction of BeCl2 with the Carbodiphosphorane Addition
Compound O2CǟC(PPh3)2 and its Hydrolysis Product Ph3PCHP(O)Ph2
Wolfgang Petz,*[a] the late Kurt Dehnicke,[a] and Bernhard Neumüller*[a]
In Memory of Professor Kurt Dehnicke
Keywords: Beryllium; X-ray diffraction; Ylides; Carbodiphosphorane adducts; (BeO)5 ring
Abstract. Reaction of BeCl2 and (PPh4)[Be2Cl6] with Ph3PCHP(O)Ph2
ane crystals of (H2C{PPh3}2)[BeCl4] (6) and (H2C{PPh3}2)Cl2·
(2) and of BeCl2 with O2CǟC(PPh3)2 (3) were studied under various CH2Cl2 (7) separated. The cluster [Be6(OH)6Cl5(O2C2{PPh3}2)3]Cl
conditions. Whereas the addition compound of 2 with BeCl2 could only
traced by 31P NMR spectroscopy the molecular structure of the O-ad-
dition compound [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2 (5) from 2 and
(PPh4)[Be2Cl6] could be performed. From 3 and BeCl2 in dichlorometh-
(8) formed upon unintentionally admitting some humidity to the initial
reaction mixture. In 8 each of the bidentate ligands 3 bridges two dif-
ferent beryllium atoms via the oxygen atoms. All compounds are charac-
terized by X-ray diffraction analyses.
1 Introduction
The double ylide hexaphenylcarbodiphosphorane C(PPh3)2
(1)[1] has a bent conformation[2] and can be considered as a
divalent carbon(0) atom, which is stabilized by two neutral
phosphine ligands, thus attaining eight electrons. 1 is endowed
with two high lying occupied MO’s at the carbon atom of σ
and π symmetry (HOMO and HOMO-1) which is established
Scheme 1. Structures of the Lewis bases Ph3PCHP(O)Ph2 (2) and
by NBO analysis. Those compounds are also named car- O2CǟC(PPh3)2 (3).
bones[3] and were subjects of preparative[4] and theoretical
studies.[5]
The hydrolysis product 2 has also ylidic character and can
be considered as derived from the ylide Ph3P = CH2 in which
one proton is replaced by the P(O)Ph2 group. However, the
chemistry of 2 is only sparingly explored so far. Coordination
of Lewis acids at the carbon atom and the oxygen atom is
possible and the first compounds reported were
1 reacts easily with wet air to produce quantitatively the
hydrolysis product Ph3PCHP(O)Ph2 (2)[1] and with CO2 the
addition compound O2CC(PPh3)2 (3) is quantitatively formed
as depicted in Equation (1) and Equation (2), respectively.[6]
Similar addition compounds with CS2 or COS also exist.
[Ph3PCHP(OW{CO}5)Ph2][7]
and
the
salt
[Ph3PCH2P(OAlBr3)Ph2][AlBr4];[8] further neutral or cationic
addition compounds of 2 were reported recently by us.[9]
Compound 2 is expected to coordinate at a Lewis acids ac-
cording to coordination mode I to IV as depicted in Scheme 2.
Main group or transition metal electron deficient species prefer
I but also III is realized, however with M = H+ at the carbon
atom.[7] Cationic compounds of mode II exist with M = H+ or
Me+;[10] no example with mode IV is known so far.
1 + H2O Ǟ Ph3PCHP(O)Ph2 (2) + C6H6
(1)
1 + CO2 Ǟ O2CC(PPh3)2 (3)
(2)
2 is also found in small amounts as byproduct during the
preparation of 1. As shown in Scheme 1 the compounds 2 and
3 have in common, that they are Lewis bases according to free
pairs of electrons at carbon (2) or at oxygen atoms (2 and 3)
prone to coordinate at various Lewis acids.
Since the first description 50 years ago the carbon dioxide
adduct 3 has found no further attention until recently. 3 is in-
soluble in toluene and is unstable in halogenated hydrocarbons,
where slow proton abstraction with formation of the cation
(HC{PPh3}2)+ could be traced by 31P NMR spectroscopy.
Scheme 3 shows the simplest and most reliable coordination
modes of 3 with coordination to one or two Lewis acids. 3 can
coordinate to a metal fragment via one oxygen atom[11] or can
act as a chelating ligand[12] due to coordination modes A and
* Prof. Dr. W. Petz
E-Mail: petz@staff.uni-marburg.de
* Prof. Dr. B. Neumüller
Fax: +49-6421-2825653
E-Mail: neumuell@chemie.uni-marburg.de
[a] Fachbereich Chemie
Philipps-Universität Marburg
Hans-Meerwein-Strasse
35032 Marburg, Germany
Z. Anorg. Allg. Chem. 2011, 637, 1761–1768
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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W. Petz, K. Dehnicke, B. Neumüller
ARTICLE
Scheme 2. Possible coordination modes I to IV of 2.
Scheme 3. Possible coordination modes A to C of 3.
B, respectively; complexes of 3 were also obtained as byprod- equimolar amounts of 2 gives a clear solution. In the 31P NMR
ucts upon reactions of 1 with transition metal carbonyl com- spectrum of the reaction mixture two sets of doublets in 1:4
plexes via a Wittig type reaction where both oxygen atoms ratios were recorded indicating the formation of two different
stem from CO.[13] Compounds with mode C are not described products. The minor product shows signals at δ = 36.1 and
2
so far.
19.7 ppm with J(P,P) = 17.9 Hz and the signals of the major
Having in mind these properties we studied reactions of the product appear at δ = 31.4 and 19.7 ppm with 2J(P,P) =
Lewis bases 2 and 3 with BeCl2 and of 2 with [Be2Cl6]2–. The 21.5 Hz. No coupling between Be (100%, I = 3/2) and phos-
9
Be2+ cation is extremely small (ion radius of 27 pm), strongly phorus could be measured; J(Be,P) is probably too small to
2
polarizing and as a hard Lewis acid has a strong oxophilic be detected. Layering of the solution with n-pentane gave an
character; the preferred coordination number is four but coor- oil from which colorless crystals separated after several weeks.
dination number three is also found. Surprisingly, the number The crystals turned out to be the neutral product
of crystal data of beryllium compounds is limited. Here we [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2 (5). Initially, we ex-
report on the results of the reaction of BeCl2 with the ylide 2 pected the formation of the salt (PPh4)[Ph3PCHP(OBeCl3)Ph2]
and the CO2 adduct 3.
and the origin of the proton is as yet unclear; deprotonation of
the solvent seems to be reliable. The IR spectrum exhibits two
strong bands in the region of PO bond vibration at 1164 and
1113 cm–1; related bands at 1184 and 1117 cm–1 were found in
the spectrum of the cation [Ph3PCH2P(O)Ph2]+. To the best of
our knowledge, 5 is the first compound with an all terminal
Cl3BeO unit. Only Be2Cl5(μ-OR) units were described so far,
in which OR groups act as a bridging ligands.[15]
2 Results and Discussion
2.1 Reaction of 2 with BeCl2 and (PPh4)[Be2Cl6]
The reaction of BeCl2 with 2 was performed in CH2Cl2 solu-
tion. In the 31P NMR spectrum of the solution the two doublets
of 2 at δ = 27.3 and 20.6 ppm (2J(P,P) = 19.7 Hz) have disap-
peared in favor of two new doublets at δ = 37.4 and 18.5 ppm
(2J(P,P) = 21.5 Hz) indicative for adduct formation Cl2Beǟ2
(4). For electronic reasons 4 must be dimeric or 2 is acting as
2.2 Reaction of BeCl2 with 3
The reaction of BeCl2 with the carbon dioxide adduct 3 was
a chelating ligand by additional HC–Be coordination. Layering studied in several runs. A 1:1 ratio of the components in
of the DCM solution with n-pentane generated only thin fi- CH2Cl2 produced a clear solution from which after evaporation
brous crystals which were not suitable for X-ray analysis. Pre- of the solvent an oily residue remained. The IR spectrum of
cipitation with n-pentane gave a colorless microcrystalline so- the oil exhibits bands at 1547 and 1380 which can be assigned
lid which is soluble in DMSO. In this solvent, however, a dra- to the CO2 group and were also found in the spectrum of the
matic change in the shifts in the 31P NMR spectrum has oc- tin complex [Cl2Sn(OC(O)C(PPh3)2)].[11] No crystals sepa-
curred with formation of two new doublets at δ = 23.6 and rated from the oil even after storage of the oil for two months
22.1 ppm (2J(P,P) = 14.1 Hz). From other experiments we at low temperature. The 31P NMR spectrum of the oil in
know that this signal is due to the cation [Ph3PCH2P(O)Ph2]+ CH2Cl2 exhibits five signals in a narrow range between δ =
(Hǟ2)+. The same set of signals was found if pyridine was 21.7 and 20.1 ppm; the main signal is at δ = 21.5 ppm. Layer-
added to the DCM solution of 4; crystals from these solution ing the solution with n-pentane gave colorless crystals of
turned out to be (Hǟ2)Cl.
(H2C{PPh3}2)[BeCl4] (6) as the major product; further ad-
In a further run 2 was allowed to react with (PPh4)[Be2Cl6] dition of n-pentane gave an oil from which crystals of
in DCM. The [Be2Cl6]2– anion consists of two edge bridged (H2C{PPh3}2)Cl2·CH2Cl2 (7) separated after some weeks. 6
tetrahedron where the chlorine bridges can easily be cleaved and 7 are the result of loss of CO2 of 3 followed by deproton-
even by weak Lewis bases with ring opening.[14] Addition of ation of DCM. The cation in 6 exhibits a signal at δ = 19.2 ppm
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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 1761–1768

Reaction of BeCl2 with O2CǟC(PPh3)2 and Ph3PCHP(O)Ph2
in the 31P NMR spectrum in CDCl3 and the addition of (Hǟ1) the DMSO complex [Be(DMSO)4]Cl2 (1.619 (5) Å)[18] and
I to the solution gave rise to a new signal at δ = 20.0 ppm for especially to those with a comparable Ph3PO complex as in
(Hǟ1)+. The presence of the BeCl4 anion prevents the cation [(NO3)2Be(OPPh3)2] were a mean value of 1.590 Å was re-
from dissociation. The salt 6 is the first one belonging to the corded.[19] The Be–Cl bond lengths are in the range of those
AB type; the other known salts with the same cation are of the reported for tetrachloroberyllates but are slightly longer than
AB2 type.,[16,17]
in BeCl3 adducts with N-donors.[15] The C–P bonds to C(1)
In a second run the DCM solution of the oil was again lay- differ by about 0.04 Å and correspond to single bonds; the
ered with n-pentane. An oily precipitated from which after different P–C bond lengths in 2, amounting to 1.717(3) Å (PO)
standing for several months two sorts of colorless crystals have and 1.688(3) Å (PPh3), have both increased to 1.841(5) Å and
–
grown. The minor product turned out to be the salt 7. The 1.803(5) Å, respectively, upon H+ and BeCl3 addition, di-
major amount of crystals were found to be the unusual cluster rected to P–C single bonds. The most drastic change of about
compound [Be6(OH)6Cl5(O2C2{PPh3}2)3]Cl (8). The forma- 1.2 Å has occurred due to loss of the π-type electron pair,
tion of 8 needs contact to some humidity which probably was which in 2 is involved in back bonding into PCPh σ* orbitals
introduced by a leaking stopcock. The spine of 8 is a ten- with formation of a partial double bond. According to rehy-
membered ring of five Be2+ and five OH– ions and one exocy-
clic Be2+ ion (Scheme 4). The charge of the ring system is 11+
(6 Be = 11+, 6 OH = 6–, 5 Cl = 5–) and one of the six OH–
groups acts as bridge between two beryllium atoms across the
ring as shown in Scheme 2; one Cl– ion is free in the crystal
lattice. Three molecules of 3 hold the assembly together as
shown in Scheme 2.
Scheme 4. Simplified view of the cation of [Be6(OH)6Cl5(O2C2{PPh3}2)3]Cl
(8).
Figure 1. Molecular structure of [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2
(5) showing the atom numbering scheme The ellipsoids are drawn at
a 40% probability level; solvent molecule and hydrogen atoms are
3 Crystal Structures
omitted for clarity.
Crystallographic data could be obtained for the compounds
5, 6, 7, and 8; crystals were formed as described above and the
molecular structures are shown in Figure 1, Figure 2, Figure 3,
Figure 4, and Figure 5; crystallographic data are collected in
Table 1; bond lengths and angles are summarized in Table 2,
Table 3, Table 4, and Table 5.
3.1 Crystal Structure of [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2
(5)
The unit cell of 5 contains two independent molecules from
which one is depicted in Figure 1. Related cationic compounds
with the group 13 Lewis acids BF3, BI3 and AlBr3 were de-
scribed recently.[8,9] The P–O bond length in 5 amounts to
1.498(3) Å which is significantly shorter than the related
average bond length in the cationic compounds (1.533(2) Å)
and only slightly longer than in 2 (1.489(2) Å), which means
that the PO π bonding is not very unbalanced by the coordina-
tion of the BeCl3 group. A remarkable long Be–O bond length
Figure 2. Molecular structure of (H2C{PPh3}2)[BeCl4]·CH2Cl2 (6)
showing the atom numbering scheme The ellipsoids are drawn at a
40% probability level. Solvent molecule and hydrogen atoms are omit-
ted for clarity. Compound 6 forms centrosymmetrical dimers via hy-
of 1.657(7) Å is found relative to the mean bond lengths in drogen bonding.
Z. Anorg. Allg. Chem. 2011, 1761–1768
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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1763

W. Petz, K. Dehnicke, B. Neumüller
ARTICLE
Figure 5.EnvironmentoftheBe6coreof[Be6(OH)6Cl5(O2C2{PPh3}2)3]+
(8); each pair O(2/3), O(5/6), and O(8/9) belong to one ligand of 3.
Figure 3. Molecular structure of (H2C{PPh3}2)Cl2·CH2Cl2 (7) show-
ing the atom numbering scheme The ellipsoids are drawn at a 40%
probability level. The hydrogen atoms at the phenyl rings are omitted
for clarity.
by four hydrogen bridges. The Be–Cl bonds involved in bridg-
ing are slightly longer than the free ones. The Cl–Be–Cl angles
range between 108.9(3)° and 113.1(2)°; the deviation from the
ideal tetrahedral angle is larger than in related salts.[20] The
DCM molecules are incorporated into the holes between the
dimers. No deviation of the parameters of the cation relative
to those of the related chlorides 7·DME and 7·CH2Cl2 could
be recognized.
3.3 Crystal Structures of (H2C{PPh3}2)Cl2·CH2Cl2 (7)
The bond lengths of the phosphorus atoms to the sp3 hy-
bridized atom C(1) are due to a normal single bond averaging
to 180.7(3) pm and are slightly shorter than those in 6
(181.7(4) pm). The bonds are longer than to the sp2 hybridized
phenyl carbon atoms (average 179.4 pm). The molecular struc-
ture of 7 is closely related to that of (H2C{PPh3}2)Cl2·DME
published earlier.[21] In all compound with the dication the
P(1)–C(1)–P(1) angles are close together ranging between 111
and 113°. The different solvents included in the crystal do not
markedly influence the bonding parameters of the dication
(H2C{PPh3}2)+. In the related salt (H2C{PPh3}2)Cl2·DME the
DME molecule is disordered and not connected by hydrogen
bridges, whereas the DCM molecule in 7 forms bridges to the
chloride anions as depicted in Figure 3. In both compounds
contacts are formed between H(1) to Cl(1) and H(2) to Cl(2)
with C(1)···Cl(1)/C(1)···Cl(2) distances of 336.3(3)/332.4(3) in
(H2C{PPh3}2)Cl2·DME and 338.2(3)/337.8(3) in 7.
Figure 4. Molecular structure of the cation of [Be6(OH)6Cl5-
(O2C2{PPh3}2)3]Cl·3.25CH2Cl2 (8) showing the atom numbering
scheme The ellipsoids are drawn at a 40% probability level; solvent
molecules and the hydrogen atoms are omitted for clarity.
bridization at C(1) the P(1)–C(1)–P(2) angle has decreased
from 117.5(2)° in 2 to 118.6(3)° in 5. A very acute P(1)–O(1)–
Be(1) angle of 143.9(3) is measured and contrasts to those
found in [(NO3)2Be(OPPh3)2] being at 173 and 159°.[23]
3.4 Crystal Structure of [Be6(OH)6Cl5(O2C2{PPh3}2)3]Cl·
3.25CH2Cl2 (8)
Themolecularstructureofthe[Be6(OH)6Cl5(O2C2{PPh3}2)3]+
cation is shown in Figure 4: Figure 5 depicts the environments
3.2 Crystal Structure of (H2C{PPh3}2)[BeCl4]·CH2Cl2 (6)
As shown in Figure 2 two (H2C{PPh3}2)[BeCl4] units form of the six Be2+ cations. The beryllium atom and the OH groups
a centrosymmetric dimer and anions and cations are connected form a 10-membered ring bridged by the O(1)H(1) group. A
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Z. Anorg. Allg. Chem. 2011, 1761–1768

Reaction of BeCl2 with O2CǟC(PPh3)2 and Ph3PCHP(O)Ph2
Table 1. Crystallographic data of the compounds [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2 (5), (H2C{PPh3}2)[BeCl4]·CH2Cl2 (6), (H2C{PPh3}2)Cl2·
CH2Cl2 (7), and [Be6(OH)6Cl5(O2C2{PPh3}2)3]Cl·3.25CH2Cl2 (8).
5
6
7
8
formula
C
31.75H28.5BeCl4.5OP2
C38H34BeCl6P2
774.36
14.044(1)
18.758(1)
14.200(1)
90
102.58(1)
90
0.28ϫ 0.11ϫ 0.05
3661.3(4)
4
C38H34Cl4P2
694.39
8.842(1)
26.783(1)
14.642(1)
90
101.67(1)
90
0.42ϫ 0.05ϫ 0.04
3395.8(5)
4
C117.5H102.5Be6Cl11.5O11P6
2386.50
23.221(1)
15.591(1)
32.561(2)
90
103.59(1)
90
0.24ϫ 0.23ϫ 0.11
11460(1)
4
mw /g mol–1
a /Å
656.52
8.362(1)
19.295(1)
19.931(1)
74.56(1)
89.37(1)
80.89(1)
0.28ϫ 0.15ϫ 0.1
3059.0(4)
4
b /Å
c /Å
α /°
β /°
γ /°
crystal size /mm
volume /Å3
Z
dcalc /g·cm–3
crystal system
space group
diffractometer
radiation
temperature /K
μ /cm–1
1.426
1.405
1.358
1.383
triclinic
monoclinic
P21/c (Nr. 14)
IPDS II (Stoe)
Mo-Kα
193
5.8
monoclinic
P21/c (Nr. 14)
IPDS II (Stoe)
Mo-Kα
100
4.7
monoclinic
P21/c (Nr. 14)
IPDS II (Stoe)
Mo-Kα
100
4.45
¯
P1 (Nr. 2)
IPDS II (Stoe)
Mo-Kα
100
5.61
2θmax/°
56.84
52.17
52.64
52.04
index range
–11 Յ h Յ 10
–25 Յ k Յ 25
–26 Յ l Յ 25
31828
–17 Յ h Յ 17
–23 Յ k Յ 23
–16 Յ l Յ 17
49810
–11 Յ h Յ 11
–33 Յ k Յ 33
–18 Յ l Յ 18
33643
–28 Յ h Յ 28
–19 Յ k Յ 19
–40 Յ l Յ 37
94533
number of rflns
collected
number of indep. 15199 (0.1163)
rflns (Rint
7234 (0.1303)
3980
6878 (0.1146)
3470
22313 (0.3347)
6520
)
number of ob-
served rflns with
F0 Ͼ 4σ (F0)
parameters
6858
731
433
406
1020
absorption correc- numerical
tion
numerical
numerical
numerical
structure solution direct methods SIR-92[25] direct methods SHELXS-97[26] direct methods SIR-92[25]
direct methods SIR-92[25]
SHELXL-97[27]
refinement
SHELXL-97[27]
SHELXL-97[27]
SHELXL-97[27]
against F2
hydrogen atoms
calculated positions with calculated positions with com- calculated positions with com- calculated positions with
common displacement pa- mon displacement parameter.
mon displacement parameter.
H(1) and H(2) were refined
common displacement pa-
rameter
rameter
H(1) and H(2) were refined
free
free
R1
0.0683
0.1585
0.0535
0.1153
1.11
0.0368
0.0503
0.246
0.0974
0.2568
0.851
wR2 (all data)
max. electron den- 0.873
sity left/e·Å–3
Table 2. Selected bond lengths /Å and angles /° of (H2C{PPh3}2) and Be(6) is in a Cl2O2 environment. All OH groups act as
Cl2·CH2Cl2 (7).
bridging ligands and one in a μ3-way, whereas the chlorine
atoms are bonded in a terminal manner. Each molecule of 3
bridges two beryllium atoms; the four beryllium atoms Be(3)
to Be(5) have contact to one oxygen atom, Be(1) to two oxy-
gen atoms of 3 and Be(6) has no contact. The Be–OH bond
lengths range from 1.57(2) to 1.72(1) Å; the three longest be-
long to those to O(1) bridging three beryllium atoms. A series
of compounds are known with six membered BeO rings via
bridging OH groups; the average Be–O bond lengths to the
bridging OH groups range between 1.586 and 1.593 Å. The
other two coordination sites at the three ring beryllium atoms
are occupied by O or N donors.[22] The coordination to the
beryllium atoms has remarkable influence on the structural pa-
rameters of 3. As expected the mean C–C bond length de-
creases to 1.46(1) Å from 1.494(3) Å in free 3 and the mean
7
C(1)–P(1)
C(1)–H(1)
P(1)–C(8)
P(1)–C(2)
P(2)–C(26)
181.3(3)
102(2)
179.7(3)
179.0(3)
179.6(3)
C(1)–P(2)
C(1)–H(2)
P(1)–C(14)
P(2)–C(32)
P(2)–C(20)
181.0(3)
100(83)
178.2(3)
180.0(2)
179.6(3)
P(1)–C(1)–P(2)
P(2)–C(1)–H(1)
P(2)–C(1)–H(2)
113.3(2)
108(1)
111(2)
P(1)–C(1)–H(1)
P(1)–C(1)–H(2)
H(1)–C(1)–H(2)
107(1)
99(2)
109(2)
transannular hydrogen bridge exist between H(1) and O(12)
with O(1)···O(12) = 2.734(9) Å. For all beryllium atoms a tet-
rahedral coordination is achieved; Be(1), Be(3), and Be(4) are
in a O3Cl environment, Be(2) and Be(5) are O4 coordinated C–O distance increases by about 0.02 Å upon coordinating to
Z. Anorg. Allg. Chem. 2011, 1761–1768
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W. Petz, K. Dehnicke, B. Neumüller
Table 3. Selected bond lengths /Å and angles /° of one of the two Table 5. Selected bond lengths /Å and angles /° of [Be6(OH)6-
ARTICLE
independent molecules of [Ph3PCH2P(OBeCl3)Ph2]·0.75CH2Cl2 (5).
Cl5(O2C2{PPh3}2)3]Cl (8).
5
8
Be(1)–O(1)
Be(1)–Cl(2)
O(1)–P(1)
C(1)–P(1)
C(1)–H(11)
P(1)–C(8)
P(2)–C(20)
1.657(7) Be(1)–Cl(1)
2.037(6) Be(1)–Cl(3)
1.498(3) C(1)–P(2)
1.841(5) C(1)–H(11)
2.021(6)
2.046(6)
1.803(5)
0.9900
1.791(5)
1.793(5)
1.793(5)
Be(1)–O(1)
Be(5)–O(1)
Be(1)–O(9)
Be(2)–O(4)
Be(2)–O(3)
Be(3)–O(11)
Be(3)–Cl(2)
Be(4)–O(11)
Be(4)–Cl(3)
Be(5)–O(7)
Be(6)–O(11)
Be(6)–Cl(4)
O(2)–C(2)
1.67(1)
Be(2)–O(1)
Be(1)–O(2)
Be(1)–Cl(1)
Be(2)–O(10)
Be(3)–O(4)
Be(3)–O(5)
Be(4)–O(7)
Be(4)–O(6)
Be(5)–O(11)
Be(5)–O(8)
Be(6)–O(10)
Be(6)–Cl(5)
O(3)–C(2)
1.71(1)
1.60(1)
2.04(1)
1.59(2)
1.64(2)
1.66(2)
1.64(2)
1.66(2)
1.59(1)
1.62(1)
1.60(1)
2.15(2)
1.25(1)
1.27(1)
1.28(1)
1.45(1)
1.732(9)
1.75(1)
1.728(9)
1.72(1)
1.64(1)
1.57(2)
1.66(1)
1.64(1)
2.01(1)
1.64(1)
2.03(1)
1.61(2)
1.59(2)
2.02(1)
1.29(1)
1.30(1)
1.28(1)
1.46(1)
1.47(1)
0.9900
P(1)–C(2)
1.811(5) P(2)–C(14)
1.796(5) P(2)–C(26)
O(1)–Be(1)–Cl(1)
Cl(1)–Be(1)–Cl(2)
Cl(1)–Be(1)–Cl(3)
P(1)–O(1)–Be(1)
P(1)–C(1)–P(2)
P(1)–C(1)–H(11)
P(1)–C(1)–H(11)
O(1)–P(1)–C(2)
C(2)–P(1)–C(8)
C(2)–P(1)–C(1)
C(26)–P(2)–C(14)
C(14)–P(2)–C(20)
C(14)–P(2)–C(1)
106.3(3) O(1)–Be(1)–Cl(2)
112.0(3) O(1)–Be(1)–Cl(3)
110.9(3) Cl(2)–Be(1)–Cl(3)
143.9(3)
109.1(4)
111.4(3)
107.2(3)
118.6(3) P(2)–C(1)–H(11)
107.7
107.7
107.1
110.9(2)
110.7(2)
107.3(2)
109.6(2)
110.8(2)
107.1(2)
107.7
107.7
P(2)–C(1)–H(11)
H(11)–C(1)–H(11)
O(5)–C(40)
O(8)–C(78)
C(1)–C(2)
C(77)–C(78)
C(1)–P(1)
O(6)–C(40)
O(9)–C(78)
C(39)–C(40)
C(1)–P(2)
114.4(2) O(1)–P(1)–C(8)
111.0(2) O(1)–P(1)–C(1)
100.9(2) C(8)–P(1)–C(1)
111.3(2) C(26)–P(2)–C(20)
106.9(2) C(26)–P(2)–C(1)
109.9(2) C(20)–P(2)–C(1)
1.745(9) C(39)–P(4)
1.756(9) C(77)–P(5)
1.75(1)
C(39)–P(3)
C(77)–P(6)
O(3)–C(2)–O(2)
O(9)–C(78)–O(8)
C(2)–O(3)–B(2)
C(40)–O(6)–B(4)
C(78)–O(9)–B(1)
113.6(8) O(5)–C(40)–O(6)
112.3(9)
130.3(7)
111.9(8)
119.0(8)
114(1)
C(2)–O(2)–B(1)
Table 4. Selected bond lengths /Å and angles /° of (H2C{PPh3}2)-
[BeCl4]·CH2Cl2 (6).
117.7(7) C(40)–O(5)–B(3)
115.4(8) C(78)–O(8)–B(4)
112.1(8)
6
C(1)–P(1)
C(1)–H(1)
1.814(4)
0.87(4)/
102(2)
1.799(4)
1.797(4)
1.784(4)
2.072(5)
2.067(5)
3.578(4)
C(1)–P(2)
C(1)–H(2)
1.819(4)
1.06(4)
ments.[15] The small seize and strongly polarizing character of
the Be2+ ion is the basis of its strong oxophilicity. 2 and 3 are
equipped with hard oxygen atoms and should be prone to coor-
dinate at the beryllium atom. However, the lack of getting suit-
able crystals in most cases prevented characterization of the
simple addition compounds. In general for 2 and 3 the coordina-
tion modes A, B, C (3) and I to IV (2) are to be expected
(Scheme 3). Whereas compounds of type A and B were reported
previously by us, mode C is realized in the cluster complex 8
described in this contribution (Scheme 4). The neutral complex
5 is represented by coordination mode III but in which M at
the carbon atom is replaced by hydrogen. In the case of 2 exam-
ples for coordination mode IV are missing so far.
P(1)–C(8)
P(1)–C(2)
P(2)–C(26)
Cl(1)–Be(1)
Cl(3)–Be(1)
C(1)···Cl(1A)
P(1)–C(14)
P(2)–C(32)
P(2)–C(20)
Cl(2)–Be(1)
Cl(4)–Be(1)
C(1)···Cl(3)
1.802(4)
1.797(4)
1.797(4)
1.992(6)
2.046(6)
3.550(4)
P(1)–C(1)–P(2)
112.0(2)
109(3)
103(2)
110.0(3)
108.9(3)
113.1(2)
176(3)
P(1)–C(1)–H(1)
P(1)–C(1)–H(2)
H(1)–C(1)–H(2)
Cl(1)–Be(1)–Cl(3) 107.6(2)
Cl(2)–Be(1)–Cl(3) 109.9(3)
Cl(3)–Be(1)–Cl(4) 107.6(3)
103(3)
110(2)
109(4)
P(2)–C(1)–H(1)
P(2)–C(1)–H(2)
Cl(1)–Be(1)–Cl(2)
Cl(1)–Be(1)–Cl(4)
Cl(2)–Be(1)–Cl(4)
C(1)–H(1)···Cl(1A)
C(1)–H(2)···Cl(3)
164(3)
The reaction of 3 with Lewis acids in halogenated hydro-
carbons undergoes a competitive reaction between additionand
deprotonation of the solvent to give the cation (Hǟ1)+. 31P
NMR experiments on solutions of 3 in DCM or 1,2-dichloroe-
thane showed that the signal of 3 at δ = 14 ppm disappeared
within some hours in favor of the signal of the cation. In the
case of 1,2-dichloroethane as solvent a further competitive re-
action was observed between formation of the cation and a
substitution reaction resulting in ClCH2CH2OC(O)C(PPh3)2.[23]
The first results from the reaction of 2 and 3 with beryllium
halides are very promising and can be seen as a challenge for
further studies in this area.
the beryllium atoms. As a consequence of the electron with-
drawing effect of the beryllium atoms the mean value of the
P–C bond lengths has increased from 1.718 in 3 to 1.744 in 8,
which means that the backbonding of the π electron pair into
PCPhσ* orbitals has decreased in favor of an increasing C–C
double bond character.[11] The coordination of 3 leads to three
six-membered BeOCOBeO rings and the CO2 bite angle has
only slightly decreased from 117.7(2)° in 3 to a mean value of
113.3(9)°. The majority of angles at the beryllium atoms are
not far away from the tetrahedral angle ranging between 106
and 114°.
4 Conclusion and Outlook
5 Experimental Section
The coordination chemistry of beryllium compounds is less
All operations were carried out under an argon atmosphere in dried
developed in comparison to those of its neighboring ele- and degassed solvents using Schlenk techniques. The solvents were
1766 www.zaac.wiley-vch.de
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 1761–1768

Reaction of BeCl2 with O2CǟC(PPh3)2 and Ph3PCHP(O)Ph2
thoroughly dried and freshly distilled prior to use. The IR spectra were
run on a Nicolet 510 spectrometer in Nujol mull (The Nujol mull bands
are omitted). For the 31P NMR spectra we used the instrument Bruker
AC 300. The carbodiphosphorane C(PPh3)2 (1) was prepared accord-
1547 s, 1544 sh, 1483 m, 1437 s, 1380 vs, 1316 w, 1188 w, 1103 s,
1074 w, 1026 w, 997 m, 932 w, 795 m, 747 s, 720 s, 689 s, 525 s.
The oil was again dissolved in DCM, layered with n-pentane, causing
again separation of an oily material instead of crystals. The mixture
ing to a modified literature procedure;[24] The syntheses of hydrolysis was allowed to stand for about two month at room temperature. After
product 2[1,9] and the CO2 adduct 3[6] were described recently. BeCl2 that time a couple of colorless crystals were detected, which turned
was prepared from the elements and (PPh4)[Be2Cl6] was obtained from out to be the cluster compound [Be6(OH)6Cl5(O2C2{PPh3}2)3]-
BeCl2 and (PPh4)Cl.[14]
Cl·3.25CH2Cl2 (8). The OH groups probably originated from contact
to humidity introduced by a leaking stopcock during this period. 31P
NMR: 20.97 to 20.27 (broad), 19.94 ppm. IR (Nujol, cm–1): 3680 w
(OH), br, 3055 w, 1549 s, 1542 sh, 1483 w, 1437 s, 1385 s, 1263 w,
1105 s, 1074 w, 1051 w, 1062 w, 999m, 934 w, br, 833 m, 814 m, 745
s, 733 s, 723 s, 689 s, 525 m, 511 m, 502 m.
Reaction of 2 with BeCl2: A mixture of 2 (0.16 g, 0.33 mMol) and
BeCl2 (0.06 g, 0.07 mMol) in DCM (about 4 mL) was mechanically
stirred for 24 h at room temperature. The solution was separated from
some insoluble material by filtration. The 31P NMR spectrum of the
solution showed two doublets at δ = 37.6 and 18.5 ppm (2J(P,P) =
21.5 Hz), which indicates the formation of an addition compound
Cl2Beǟ2 (4). No suitable crystals for an X-ray analysis were formed
upon layering the solution with n-pentane. Removal of the solvent and
taking up the residue in DMSO gave a solution; the formation of the
cation [Ph3PCH2P(O)Ph2]+ (Hǟ2)+ was established by 31P NMR
spectroscopy.
Reaction of 3 with (PPh4)2[Be2Cl6]: A mixture of 3 (0.03 g, 0.04
mMol) and (PPh4)2[Be2Cl6] (0.08 g, 0.2 mMol) was dissolved in DCM
(about 3 mL) and stirred mechanically for about 11 h. The 31P NMR
spectrum of the solution showed signals at δ = 22.2 and 19.0 ppm. No
suitable crystals were obtained upon layering with n-pentane. The sol-
vent was removed in the residue dissolved in 1,2-dichloroethane and
layered with n-pentane. Needle-like crystals formed, which turned out
to be the salt 7.
In a second run attempts were made to get larger crystals by very slow
diffusion of n-pentane into a solution of a mixture of 2 (0.23 g, 0,5
mMol) and BeCl2 (0.05 g, 0.6 mMol) in DCM. Thus, in a three necked
Schlenk tube a clear solution from one neck was transferred into the
second one; the third one was supplied with n-pentane. In the course
of several weeks crystals separated, which, however, were not suitable
for an X-ray analysis. The 31P NMR spectrum of the supernatant solu-
tion showed three sets of AX signals; set 1 at 34.7, 18.8 (J(P,P) =
21.5 Hz), set 2 at 32.7, 18.7 (J(P,P) = 23.3 Hz) and set 3 at 22.7, 27.2
(2J(P,P) = 14.3 Hz) ppm; the latter could be assigned to the cation
[Ph3PCH2P(O)Ph2]+ (Hǟ2)+.
Crystallographic data for the structures have been deposited with the
Cambridge Crystallographic Data Centre, 11 Union Road, Cambridge
CB21EZ. Copies of the data can be obtained on quoting the depository
numbers CCDC-830895 (5), CCDC -830896 (6), CCDC -830897 (7),
CCDC -830898 (8) (Fax: +44-1123-336-033; E-mail: deposit@ccdc.ca-
m.ac.uk).
Acknowledgments
Reaction of 2 with (PPh4)[Be2Cl6]: A mixture of 2 (0.19 g, 0.4
mMol) and (PPh4)[Be2Cl6] (0.18 g, 0.2 mMol) was dissolved in DCM
(about 4 mL) and stirred mechanically for about 30 min. Additionally
to the signal of the cation (PPh4)+ at δ = 22.9 ppm the 31P NMR spec-
trum of the reaction mixture shows two sets of signals for the phospho-
rus atoms: set 1 with 36.05, 19.65 ppm, J(P,P) = 17.9 Hz and set 2
with 31.45, 18.77 ppm, J(P,P) = 21.5 Hz in a 1:2 ratio according to
We thank the Deutsche Forschungsgemeinschaft for financial support.
W. P. is also grateful to the Max-Planck-Society, Munich, Germany,
for supporting this research project.
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1768
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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 1761–1768