Syntheses and Crystal Structures of Copper and Silver Complexes with the Ylide Ph3PCHP(O)PPh2 as Ligand

Article abstract of DOI:10.1002/zaac.201500771

The reactivity of the hydrolysis product of hexaphenylcarbodiphosphorane, PPh₃CHP(O)Ph₂, towards different soft Lewis acids, such as CuI and Ag[BF₄] are reported. While CuI exclusively binds at the ylidic carbon atom, reaction of the silver cation in CH₂Cl₂ leads to proton abstraction from the solvent to give the cation [PPh₃CH₂P(O)Ph₂]⁺. Surprisingly, Ag⁺ replaces the methyl group of [PPh₃CHMeP(O)Ph₂]⁺ to produce a dimeric complex, in which Ag⁺ is coordinated to C and O forming an eight membered ring. The compounds were characterized by spectroscopic methods and X-ray diffraction.

Full text of DOI:10.1002/zaac.201500771

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DOI: 10.1002/zaac.201500771
Syntheses and Crystal Structures of Copper and Silver Complexes with the
Ylide Ph3PCHP(O)PPh2 as Ligand
Wolfgang Petz*[a] and Bernhard Neumüller*[a]
Keywords: Ylide ligands; Copper; Silver; Hexaphenylcarbodiphosphorane; X-ray diffraction
Abstract. The reactivity of the hydrolysis product of hexaphenyl- [PPh3CH2P(O)Ph2]+. Surprisingly, Ag+ replaces the methyl group of
carbodiphosphorane, PPh3CHP(O)Ph2, towards different soft Lewis
acids, such as CuI and Ag[BF4] are reported. While CuI exclusively
binds at the ylidic carbon atom, reaction of the silver cation in CH2Cl2
[PPh3CHMeP(O)Ph2]+ to produce a dimeric complex, in which Ag+
is coordinated to C and O forming an eight membered ring. The com-
pounds were characterized by spectroscopic methods and X-ray
leads to proton abstraction from the solvent to give the cation diffraction.
Introduction
Carbones are named compounds of the general formula CL2,
in which the carbon atom retains its four electrons attaining
noble gas configuration with help of two neutral donor mol-
ecules L.[1] The most prominent member of this class of C(0)
compounds is the carbodiphosphorane C(PPh3)2 (1). It rapidly
hydrolysis to produce the ylide Ph3PCHP(O)Ph2 (2) if brought
into contact with wet air according to Equation (1).
C(PPh3)2 + H2O Ǟ Ph3PCHP(O)Ph2 + C6H6
(1)
Although 2 was described simultaneously with the detection
of C(PPh3)2, its chemistry, however, remained unexplored for
a long time.[2] 2 can be seen as derived from the ylide
Ph3PCH2, in which one proton is replaced by P(O)Ph2. En-
dowed with a free pair of electrons at the ylidic carbon atom
along with pairs of electrons at the oxygen atom, 2 represents
a Lewis base with soft and hard sites at the same molecule,
prone to donate to various Lewis acids as depicted in
Scheme 1.
In principle 2 resembles the class of keto ylides R3PCHC(O)RЈ
or ester ylides R3PCHC(O)ORЈ’, where the P(O)Ph2 fragment
is replaced by C(O)RЈ or C(O)ORЈ groups, respectively. The
comparable constitution of 2 leads to three basic types of coor-
dination modes with soft and hard Lewis acids A as shown in
Scheme 2. Exclusive addition of A at the ylidic carbon atom
of 2 is expressed by 2(C)ǞA, while the coordination at an
electron pair of the PO group is formulated as 2(O)ǞA. If
both electron pairs are active towards Lewis acids, it is sym-
bolized by formulation Aǟ(C)2(O)ǞA.
Scheme 1. Coordination modes for soft and hard Lewis acids A at the
phosphonio-ylide Ph3PCHP(O)Ph2 (2).
Scheme 2. Possible types of addition compounds of 2 between main
group or transition metal Lewis acids.
In recent papers we reported on addition compounds of 2
with Lewis acids A such as group 13 compounds BX3 (X = F,
I), AlBr3, and SnCl2, which exclusively coordinate at the oxy-
gen atom to give neutral compounds of the type 2(O)ǞA;[3]
an O coordination was also found with the electron deficient
W(CO)5 fragment.[4] In a preceding paper, the results of the
alkylation of 2 were presented. Alkylation with MeI or
protonation proceeds at the ylidic carbon atom with quantita-
tive formation of the salts [Ph3PCHMeP(O)Ph2]I or
[Ph3PCH2P(O)Ph2]I, respectively, abbreviated as (2(C)ǞMe)+
and (2(C)ǞH)+.[5] A second row of cationic compounds was
also formed, in which additionally to O coordination the ylidic
carbon atom is protonated leading to sp3 hybridization and for-
mation of compounds of the type (Hǟ(C)2(O)ǞA)+;[6] among
them an alkylated product (Meǟ(C)2(O)ǞA)+ with A =
* Prof. Dr. W. Petz
Fax: +49-6421-2825653
E-Mail: petz@staff.uni-marburg.de
* Prof. Dr. B. Neumüller
E-Mail: neumuell@chemie.uni-marburg.de
[a] Fachbereich Chemie der Universität Marburg
Hans-Meerwein-Strasse
35032 Marburg, Germany
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AlBr3 could also be isolated.[5] The carbon atoms in 2(O)ǞA to protect the soft position and to enforce an exclusive O coor-
addition compounds show sp2 hybridization as in the starting dination. In the 31P NMR spectrum two signals at δ = 31.1
ylide 2. H+ addition as well as alkylation of 2 adopts a dis- and 30.0 ppm [2J(P,P) Ͻ 4 Hz] were found. From this solution
torted tetrahedral environment at the carbon atom.[5]
colorless crystals separated, which turned out to be the
Herein we report on a new compound of coordination mode dimeric complex [(Ag{(O)PPh2C(H)PPh3})2][BF4]2·2CH2Cl2
2(C)ǞA with A = CuI, in which only the soft site is active (6·2CH2Cl2), as shown in Scheme 3. The replacement of Me+
and on a dimeric compound with Ag+ involving donation of by Ag+ is surprising but it seems that Me+ acts as a protecting
both coordination sites. Addition compounds of 1 with transi- group preventing abstraction of a proton from the solvent by
tion metal[7] or main group Lewis acids[8] were also reported 2 to give 4. The dication of 6 is the first compound, in which
and summarized in review articles.
2 acts as a bridging ligand for two AgI ions. The molecular
structure of 6·2CH2Cl2 was confirmed by single-crystal X-ray
diffraction analysis.
Results and Discussion
In the course of our studies on the coordination chemistry
of 2 we turned to reactions with soft Lewis acids in order to
activate coordination at the free pair of electrons of the ylidic
carbon atom or to get compounds in which 2 acts as a chelating
ligand. Thus, soft cations containing weakly coordinating
anions would be suitable for this purpose. We found that the
reaction of 2 with CuI in 1,2-Br,F-C6H4 ends up with quantita-
tive formation of the neutral
C
addition complex
[Ph3PCH(CuI)P(O)Ph2] (3) as depicted in Scheme 2 of the
type 2(C)ǞA. 31P NMR signals of 2 in this solvent were re-
corded at δ = 25.3 ppm (br) and 20.3 ppm [d, J(P,P) =
14.3 Hz], which change upon coordination to Cu into two un-
resolved signals at δ = 26.5 and 23.5 ppm for 3. The complex
readily dissolves in DMSO to give unresolved signals in the
31P NMR spectrum at δ = 27.6 and 24.3 ppm. After addition
of dichloromethane to the DMSO solution two new doublets
appeared at δ = 24.3 and 23.0 ppm (J = 13.7 Hz), which were
attributed to the signals of the protonated species (2(C)ǞH)+;
proton abstraction from the solvent with loss of CuI was as-
sumed. Compound 3 is the first adduct of 2 with other than
H+ or Me+ attached at the ylidic carbon atom.
First attempts to attach Hg2+ at the ylidic carbon atom of 2
have failed. Upon reacting 2 with HgI2 in CH2Cl2 or THF we
could only isolate the cation [Ph3PCH2P(O)Ph2]+ as the
[HgI3]– salt; the proton apparently stems from the solvents.[3]
If 2 was allowed to react with Ag[BF4] in CH2Cl2 a color-
less precipitate was obtained, which after stirring for 24 h
turned black. The supernatant solution showed two doublets in
the 31P NMR spectrum at δ = 31.0 and 19.9 ppm [2J(P,P) =
14.3 Hz] but after standing for about 2 d the signals have dis-
appeared in favor of two other doublets at δ = 22.8 and
21.4 ppm [2J(P,P) = 12.5 Hz], which were attributed to the sig-
nals of (2(C)ǞH)+. Layering the solution with n-pentane pro-
duced large crystals of (Ph3PCH2P(O)Ph2)[BF4]·7/8CH2Cl2
(4·7/8CH2Cl2). We were not able to identify the product with
the set of signals at δ = 31.0 and 20.0 ppm. The signals fit to
a product from an O coordination of (2(C)ǞH)+ at Ag+ of
unknown structure; signals in a similar range were found for
neutral [Ph3PCH2P(OBeCl3)Ph2] adopting coordination mode
Scheme 3. Results of the reaction of Ph3PCHP(O)Ph2 (2) with CuI
and Ag[BF4] and of [Ph2CHMeP(O)Ph2]I (5) with Ag[BF4]. The
anions, [BF4]– of 4 and 6 are omitted for clarity.
The circumstances, why 6 is not available upon reaction of
2 with AgBF4 but surprisingly forms with the alkylated com-
pound 5 is not understood as yet and further studies on the
chemistry of 5 are currently in progress. Several runs with 2
and Ag[BF4] in halogenated hydrocarbons repeatedly produced
the cation [Ph3PCH2P(O)Ph2]+ and not 6. This confirms the
role of the methyl group as a protecting group to avoid proton
abstraction from the solvent prior to coordination of Ag+ oc-
curs.
The structures of compounds 3, 4·7/8CH2Cl2, and
6·2CH2Cl2 were determined by single-crystal X-ray diffraction
analysis. Crystals were grown at room temperature upon layer-
ing solutions of the compounds with n-pentane. Both transition
metal adducts of 2 are chiral and the unit cells contain pairs
of enantiomers.
Crystal Structure of 3
The molecular structure of 3 is shown in Figure 1. The com-
Hǟ(C)2(O)ǞA.[9] To avoid proton extraction from the sol- pound crystallizes without including a solvent molecule. Ac-
vent, the reaction between 2 and Ag[BF4] was also carried out cording to the chirality of 3 the unit cell contains two pairs of
in 1,2-Br,F-C6H4 as the solvent but without success.
enantiomers. Relative to 2, the P–C distances have increased
We have also studied the reaction of Ag[BF4] in dichloro- by about 0.07 Å upon attachment of the CuI molecule at the
methane with the alkylated compound 5 (as the iodide) in order ylidic carbon atom. However, as shown in Table 1, the effect
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Table 1. Comparison of structural parameters /Å,° of known C coordinated compounds [Ph3PCH(A)P(O)Ph2].
A
P(1)O–C(1)
P(2)–C(1)
Δ
P(1)–O(1)
P(2)–C(1)–P(1)
Ref.
[3]
this work
this work
[5]
– (2)
1.717(3)
1.795(6)
1.839(4)
1.846(3)
1.688(3)
1.756(5)
1.797(4)
1.827(3)
0.029
0.039
0.042
0.019
1.489(2)
1.500(4)
1.494(3)
1.481(2)
127.5(2)
118.4(3)
119.2(2)
114.2(2)
CuI (3)
H+ (4)a)
Me+ (5)b)
a) Angles between 118.4(5)° and 121.1(4)° were recorded with other anions.[5] b) Mean value from two compounds.
is more pronounced if a proton or a methyl group takes seat carbon atom. Among them, the largest P(2)–C(1)–P(1) angle
of the copper iodide. The Cu–C distance of 1.964(5) Å in 3 is is found in 4·7/8CH2Cl2 although these angles are located in a
that of Cu to a sp3 carbon atom; it turns out slightly longer narrow range between 114° (5) and 119° (4·7/8CH2Cl2). The
than that to an sp2 carbon atom as in the linear cationic dicar- sp3 environment of the carbon atom is not very sensitive to the
bone complex [Cu{C(PPh3)}2]+ amounting to 1.944(5) Å.[10] nature of the Lewis acid but relative to 2 (sp2 carbon atom) a
In the 1:1 addition complexes of C(PPh3)2 (1) with CuCl and reduction of the P(2)–C(1)–P(1) angle of about 10° is found.
Cu(C5Me5) the Cu–C bond lengths drop down to The influence on the size of the P–C–P angle is not yet clear.
1.906(2) Å[11] and 1.922(6) Å,[12] respectively. Similar short Packing effects, size of the ligand A, and hybridization of the
values were found in the addition compound between the central carbon atom finally are prearranging factors.
mixed carbone (iPr2N)2MePǞCǟSPh2 and CuN(SiMe3)2
amounting to 1.903(4) Å.[13] It is interesting to note that in
related Cu-NHC addition compounds, Cu–C distances between
1.877(4) Å and 1.938(5) Å were found.[14]
Crystal Structure of 4·7/8CH2Cl2
The molecular structure of 4·7/8CH2Cl2 is shown in Fig-
ure 2. In the solid state OH bridges to a second molecule with
C(1)···O(1a) distances of 3.449(5) Å and HF bridges with
C(1)···F(11) distances of 3.308(4) Å were found. The [BF4]–
ion is disordered in two positions whereas the atoms B(11),
F(11) and F(31) are present in both split positions. Table 1 lists
important parameters of only C coordinated compounds.
Figure 1. Molecular structure of [Ph3PCH(CuI)P(O)Ph2] (3) showing
the atom numbering scheme. The ellipsoids are drawn at a 40% prob-
ability level. Thin lines represent the phenyl rings. Selected bond
lengths /Å and angles /°: C(1)–Cu(1) 1.964(5), Cu(1)–I(1) 2.3783(8),
P(2)–O(1) 1.500(4), P(1)–C(1) 1.795(6), P(2)–C(1) 1.756(5), C(1)–
H(1) 1.0000; C(1)–Cu(1)–I(1) 173.6(2), P(2)–C(1)–P(1), 118.4(3),
P(2)–C(1)–Cu(1) 105.0(3), P(1)–C(1)–Cu(1) 113.1(3), O(1)–P(1)–C(1)
116.9(2), P(2)–C(1)–H(1) 106.5, P(1)–C(1)–H(1) 106.5, Cu(1)–C(1)–
H(1) 106.5.
Figure 2. Crystal structure of (Ph3PCH2P(O)Ph2)[BF4]·7/8CH2Cl2
(4·7/8CH2Cl2). The phenyl groups are drawn as thin lines; the
hydrogen atoms at the phenyl rings and the solvent molecules are omit-
ted for clarity. Selected bond lengths /Å and angles /°: C(1)–P(1)
1.839(4), C(1)–P(2) 1.797(4), O(1)–P(1) 1.494(3); P(2)–C(1)–P(1)
119.2(2), O(1)–P(1)–C(8) 113.8(2), O(1)–P(1)–C(2) 111.4(2), O(1)–
P(1)–C(1) 114.2(2).
Among the derivatives of 2 with an exclusive C coordina-
tion the compounds 3, 4·7/8CH2Cl2, and 5 represent the unique
examples known so far and some bonding parameters are com-
pared in Table 1. Both P–C distances increase in the order
CuI Ͻ H+ Ͻ Me+ indicating an increase of single bond charac-
ter; however, the difference Δ between both P–C distances
reaches a maximum in 4·7/8CH2Cl2. The P–O distances are
Crystal Structure of 6·2CH2Cl2
The structure of [(Ag{(O)PPh2C(H)PPh3})2][BF4]2·
less sensitive upon addition of a Lewis acid A at the ylidic 2CH2Cl2 (6·2CH2Cl2) was confirmed by X-ray analysis and
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the structure of the cations is shown in Figure 3. Two cations pronounced. The different P–C bond lengths in 2, amounting
form a centrosymmetric dimer of enantiomers. In the resulting to 1.717(3) Å (PO) and 1.688(3) Å (PPh3), have both increased
eight-membered rings each silver cation is bonded to one car- to 1.781(3) Å and 1.771(3) Å, respectively, upon complex for-
bon and one oxygen atom of 2 and 2Ј, respectively. The mation, directed to P–C single bonds. The most drastic change
Ag–CH bond length amounts to 2.184(3) Å and is of about 0.08 Å in the C to PPh3 bond has occurred due to
slightly shorter than that found in the trication loss of the π-type electron pair, which in 2 is involved in
[(Ph3P)2CHǞAgǟCH(PPh3)2]3+ [2.209(6) Å] (7), in which a back bonding into PC σ* orbitals with formation of a partial
comparable bond to an ylidic carbon atom is operative.[15] For double bond. The same trend is found in (Hǟ(C)2(O)ǞA)+
the Ag–O bond length a value of 2.144(2) Å was found, which adducts, in which the ylidic carbon atom is additionally proton-
is about 0.10 Å shorter than in complexes with carboxylates as ated.[5, 6]
ligands [X–Y–Z = OC(R)O] (see type I compounds in
As stated above, 2 is an ylide with a free pair of electrons
Scheme 5).[16–18] The Ag·····Ag contact amounts to 2.8668 Å and the proximity of an oxygen atom to the central ylidic unit
leading to a wavy eight membered ring. The contact is close is the same as in carbonyl stabilized keto ylides such as
to that in elemental silver (2.89 Å).[19] The O–P–C bite angle Ph3PCHC(O)R or ester ylides Ph3PCHC(O)OR and compari-
of 2 has not changed in going to 6·2CH2Cl2 upon complex son in chemical behavior can be drawn. In contrast to 2, keto
formation remaining at 114°. The P(1)–C(1)–P(2) angle is ylides are known for their rich coordination chemistry.[20] In
127.5(2)° in 2 and goes down to 118.2(2)° in 6·2CH2Cl2; 1987 Vicente published the silver complex 8 with a linear C–
nearly the same angles are found in (Hǟ(C)2(O)ǞA)+ com- Ag–C arrangement without contacts of the silver cation to the
pounds. A slightly bent arrangement with a C–Ag–O angle of carbonyl oxygen atom of the ketoylide.[20] A similar complex
170.8° was found and the sum of the angles at the silver atom with a linear C–Ag–C array was reported by us recently upon
is 347.5° indicating a pyramidal environment at Ag. As de- coordinating the cation [HC(PPh3)2]+ at Ag+ with formation of
picted in Figure 3 no further contacts to the Ag atoms exist; the the trication 7 (Scheme 4)
ions and dichloromethane molecules are connected by weak
hydrogen bridges; the nearest contacts are C(1)···F(1) =
3.225(8) Å and C(32)···F(2) = 3.121(8) Å. The P–O bond
length has slightly elongated upon complex formation from
1.489(2) to 1.512(2) Å; this is less than found in adducts of 2
with main group Lewis acids[3] where the elongations are more
Scheme 4. Known linear addition compounds of Ag+ with ylides.
6 belongs to a series of dinuclear coinage metal complexes
which form an eight-membered ring of type I with a transannu-
lar metal-metal interaction due to a d10-d10 closed shell attrac-
tion as depicted in Scheme 5; 6 is the only compound within
this series with a carbon to silver bond so far. The scope of
X–Y–Z bridges for the M···M unit comprises neutral and an-
ionic species.
Scheme 5. Structural motif of dinuclear silver complexes with chelat-
ing X–Y–Z ligands and Ag····Ag interaction.
A comparison of the most relevant structural data of com-
Figure 3.
Molecular
structure
of
the
dication
of
[(Ag{(O)PPh2C(H)PPh3})2][BF4]2·2CH2Cl2 (6·2CH2Cl2). The phenyl parable type I compounds, in which the Ag atoms similarly
groups are drawn as thin lines; the hydrogen atoms at the phenyl rings,
the anions, and the solvent molecules are omitted for clarity. Selected
marized in Table 2. All compounds have a baggy eight-mem-
bond lengths /Å and angles /°: Ag(1)–O(1A) 2.144(2), Ag(1)–C(1)
2.184(3), O(1)–P(1) 1.512(2), C(1)–P(1) 1.781(3), C(1)–P(2) 1.771(3),
C(1)–H(1) 0.92(4), Ag(1)–Ag(1A) 2.8670(5); O(1A)–Ag(1)–C(1)
have no further contacts to other donor ligands as in 6, is sum-
bered ring and the Ag···Ag contacts range between 2.71 and
2.97 Å showing great flexibility.[21]
170.8(1), O(1A)–Ag(1)–Ag(1A) 85.63(6), C(1)–Ag(1)–Ag(1A)
91.11(9), P(1)–O(1)–Ag(1A) 121.7(1), P(2)–C(1)–P(1) 118.2(2), P(2)–
C(1)–Ag(1) 104.3(1), P(1)–C(1)–Ag(1) 107.3(1), P(2)–C(1)–H(1)
108(2), P(1)–C(1)–H(1) 110(2), Ag(1)–C(1)–H(1) 109(2), O(1)–P(1)–
C(1) 114.0(1), O(1)–P(1)–C(8) 111.4(1), C(1)–P(1)–C(8) 106.2(1),
O(1)–P(1)–C(2) 107.8(1).
Theoretical studies on type I compounds were undertaken
by Pyykkö et al.[22] and related compounds were summarized
in a review from the same author.[23] According to relativistic
effects the attraction is strong for M = Au and less important
for M = Cu, Ag. Gold complexes with P–C–P[24] and
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Table 2. Comparison of bond lengths /Å and angles /° in related type I compounds with an Ag···Ag attraction; the donating atoms are given in
bold.
X–Y–Z
Ag1···Ag2
Z–Ag
X–Ag
X–Ag–Z
X–Y–Z
Ref.
N–C–Na)
S–C–Pb)
O–C–Oc)
C–P–Od)
2.705(1)
2.9617(8)
2.967(3)
2.8670(5)
2.116(5)
2.391(1)
2.249(6)
2.144(2)
2.094(5)
2.446(1)
2.232(6)
2.184(3)
168.8(2)
173.40(4)
157.9(2)
170.8(1)
124.9(6)
116.5(2)
130.1(8)
114.0(1)
[26]
[28]
[17]
this work
a) N–C–N = [p-tolNCHNtol-p]–. b) S–C–P = PhSCH2PPh2. c) O–C–O = (OC(CF3)O)–. d) C–P–O = Ph3PCHP(O)Ph2 (2).
S–C–S[25] bridges are also reported as well as silver and cop-
per compounds with the N–C–N bridge.[26] Special gold com-
plexes with the C–P–C bridge were reported very early by the
group of Schmidbaur involving the anionic phosphorus ylide
[CH2P(Et)2CH2]– [27] however, no related silver compounds
are known. The length of the M···M contact depends on nature
of the X–Y–Z bridge. In the majority of compounds, X and
Z are equal and the structural motif is found particularly in
carboxylates as O–C–O bridge.[16,17,18] One silver compound
is reported, in which X and Z are different as in 2 with a S–
C–P bridge.[28] However, based on motif I, in which no further
ligands are attached at the Ag atoms the crystal structures of
only three silver compounds are reported. The Ag···Ag con-
tacts are in the range of 2.71 to 2.98 Å, being shorter or larger,
respectively, as in metallic silver, whereras Ag···Ag contacts in
cluster compounds range between 2.92 and 3.13 Å,[29] and in
metallic silver a value of 2.89 Å is found.[19] Quite recently,
Schmidbaur published a survey on all kinds of argentophilic
interactions.[21]
As shown in Table 2 the Y–Ag–Z angles are very flexible
varying between 157° and 173° and the bending can be inward
or outward. Small bite angles of the bridging ligand correspond
to a large angle at the silver atom. For all compounds, a T
shaped environment for the silver atoms is recorded and the
sum of the angles at each Ag atom is lower than 360°. 6 is the
first complex, in which 2 is part of an eight-membered ring
and we are sure that with suitable MX sources the number
of related complexes of coinage metals and others could be
increased.
were thoroughly dried and freshly distilled prior to use. The IR spectra
were run with a Nicolet 510 spectrometer in Nujol mull. For 31P NMR
spectra we used the instrument Bruker AV II 300 MHz. 1H and 13C
spectra were recorded with a Bruker AV III 500 MHz instrument. The
carbodiphosphorane C(PPh3)2 (1) was prepared according to
a
modified literature procedure[30] and Ph3PCHP(O)Ph2 (2) was
obtained upon hydrolysis according to Equation (1). The salt
[Ph3PCH(Me)P(O)Ph2]I (5) formed quantitatively upon reaction of 2
in MeI as the solvent.[5]
Preparation of Ph3PC(H)(CuI)P(O)Ph2 (3): A mixture of 2 (0.238 g,
0.50 mmol) and CuI (0.115 g, 0.61 mmol) was stirred in about 4 mL
of 1,2-Br,F-C6H4. A grey suspension formed. The mixture was heated
for 1 min to reflux and allowed to cool down to room temperature.
The solution was filtered from some colorless material. In the 31P
NMR spectrum of the solution, two unresolved signals at δ = 26.53
and 23.45 ppm were found. Layering of the solution with n-pentane
caused to grow crystals suitable for X-ray analysis; yield 60%. 1H
2
NMR ([D6]DMSO): δ = 7.2 to 8.0 (m, Ph), 5.39 [dd, CH, J(P,H) =
12.56, 2J(P,H) = 17.0 Hz]. 13C NMR ([D6]DMSO): δ = 126.0 to 138.5
(m, Ph), 14.90 [dd, CH, J(P,C) = 65, J(P,C) = 55 Hz]. 31P NMR
(DMSO): δ = 27.6 and 24.3 ppm. After addition of CH2Cl2 two
signals appeared at δ = 24.3 [d, 2J(P,P) = 13.7 Hz] and 23.0 [d,
2J(P,P) = 13.3 Hz], which were attributed to the protonated 2,
[Ph3PCH2P(O)Ph2]+. IR (Nujol mull): ν˜ = 1589 w, 1481 m, 1436 s,
1170 s, 1147 s, 1108 s, 1067 w, 1028 w, 998 w, 892 s, 854 w, 829 m,
747 s, 737 m, 721 m, 690 s, 577 m, 556 s, 503 s, 469 w cm–1.
Formation of (Ph3PCH2P(O)Ph2)[BF4] (4·7/8CH2Cl2): To a solution
of 2 (0.143 g, 0.30 mmol) in about CH2Cl2 (10 mL) was added AgBF4
(0.100 g) and the mixture was stirred for 24 h at room temperature.
Small amounts of a colorless precipitate formed, which was separated
from the solution. The supernatant CH2Cl2 solution showed two dou-
blets at 30.9 and 19.9 [2J(P,P) = 14.3 Hz] ppm. The CH2Cl2 solution
was layered with n-pentane to give large colorless crystals which
turned out to be (Ph3PCH2P(O)Ph2)[BF4]·7/8CH2Cl2 (4·7/8CH2Cl2);
yield about 20%. 31P NMR of the crystals in CH2Cl2: δ = 22.8, 21.4
Conclusions
Exploiting the chemistry of 2 offers various coordination
modes depending on the nature of the Lewis acid applied; 2
exhibits a high synthetic potential as ligand, similar to that of
the related keto ylides. The range of soft and hard acids from
main group or transition metal compounds may generate new
2
[d’s, J(P,P) = 12.5 Hz]. IR (Nujol mull): ν˜ = 1589 s, 1486 s, 1438 s,
1377 s, 1337 m, 1275 m, 1182 s br, 1052 s br, 924, w, 786 m, 729 m,
689 m, 557 w, 503 m cm–1.
Preparation of [(Ag{(O)PPh2C(H)PPh3})2][BF4]2·2CH2Cl2 (6): To a
adducts with interesting properties and structural diversities. solution of [Ph3PCH(Me)P(O)Ph2]I (0.116 g) in dichloromethane was
added Ag[BF4] (0.037 g) and the mixture was treated for 2 min in an
ultrasonic bath. AgI precipitated, which was separated from the solu-
tion by decantation. The 31P NMR spectrum of the solution showed
two unresolved signals at δ = 31.1 and 30.0 ppm; no Ag,P coupling
was observed. The slight yellow solution was given in one branch of
a double Schlenk tube. The other branch was supplied with n-pentane.
Slow diffusion of n-pentane into the CH2Cl2 solution caused to sepa-
rate colorless crystals in about 5% yield in the course of several days,
Furthermore, its neutral alkyl analogue Ph3PC(Me)P(O)Ph2,
which is easily obtained from 2 upon successive reaction with
MeI and K(NSiMe3)2 is object of further studies. The unusual
exchange between Me+ and Ag+ in 5 with result of 6 merits
further intense investigations in future time.
Experimental Section
which turned out to be 6·2CH2Cl2. 31P NMR (CH2Cl2): δ = 31.1, 30.0
2
General: All operations were carried out in an argon atmosphere in [d’s, J(P,P) Ͻ 4 Hz]. IR (Nujol mull): ν˜ = 1579 w, 1483 w, 1439 s,
dried and degassed solvents using Schlenk techniques. The solvents
1341 s, 1317 w, 1279 w, 1190 w, 1157 s, 1128 s, 1101 s, 1067 s,
Z. Anorg. Allg. Chem. 2016, 275–281
279
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Journal of Inorganic and General Chemistry
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ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
Table 3. Crystal data and structure refinement details for 3, 4·7/8CH2Cl2, and 6·2CH2Cl2.
3
4·7/8CH2Cl2
6·2CH2Cl2
Formula
Mw /g·mol–1
a /Å
b /Å
c /Å
C31H26CuIOP2
666.90
11.227(1)
10.563(1)
23.410(1)
90
C31.88H28.75BCl1.75F4OP2
638.59
10.623(1)
15.379(1)
18.730(1)
90
C64H56Ag2B2Cl4F8O2P4
1512.12
11.617(1)
21.988(1)
12.211(1)
90
α /°
β /°
γ /°
90.34(1)
90
90
90
94.69(1)
90
Crystal size /mm
Volume /Å3
Z
0.13ϫ0.11ϫ0.06
2776.2(4)
4
0.22ϫ0.15ϫ0.11
3059.9(4)
4
0.22ϫ0.21ϫ0.21
3108.7(4)
2
dcalc /g·cm–3
Crystal system
Space group
Diffractometer
Radiation
Temperature /K
μ /cm–1
1.596
1.386
1.615
monoclinic
P21/n (No. 14)
IPDS 2T (Stoe)
Mo-Kα
100
20.37
orthorhombic
P212121 (No. 19)
IPDS II (Stoe)
Mo-Kα
100
3.45
monoclinic
P21/n (No. 14)
IPDS II (Stoe)
Mo-Kα
100
9.74
2θmax/°
51.96
56.76
51.86
Index range
–13 Յ h Յ 13
–13 Յ k Յ 12
–28 Յ l Յ 28
17357
5375 (0.0912)
5375
–14 Յ h Յ 12
–20 Յ k Յ 19
–25 Յ l Յ 24
19979
7619 (0.1218)
2876
–14 Յ h Յ 14
–27 Յ k Յ 27
–14 Յ l Յ 15
43440
6039 (0.0592)
4611
Number of reflections collected
Number of indep. reflections (Rint
Number of observed reflections
with Fo Ͼ 4σ(Fo)
)
Parameters
326
653
393
Absorption correction
Structure solution
empirical
numerical
numerical
direct methods (Sir-92[31]
)
direct methods (Sir-92[31]
)
direct methods (Sir-92[31]
)
Refinement against F2
Flack parameter
SHELXL-97[32]
–
SHELXL-97[32]
0.43(1); refined as racemic twin
SHELXL-97[32]
–
Hydrogen atoms
calculated position with common calculated position with common calculated position with common
displacement parameter
displacement parameter
displacement parameter
R1
0.053
0.1305
0.821
0.0524
0.0913
0.653
0.0328
0.0827
0.87
wR2 (all data)
Max. electron density left
/e·pm3·10–6
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1030 s, 997 m, 986 m, 872 m, 853 w, 754 s, 737 s, 723 s, 694 s,
673 w, 561 m, 552 m, 527 m, 511 s, 502 m cm–1.
A summary of the crystallographic data and structure refinement re-
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Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-1434187 (3), CCDC-1434188 (4·7/8CH2Cl2), and
CCDC-1434189 (6·2CH2Cl2) (Fax: +44-1223-336-033; E-Mail:
deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk)
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© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Journal of Inorganic and General Chemistry
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ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
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Received: November 16, 2015
Published Online: January 25, 2016
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