Reactions of R2P-P(SiMe3)2 with [(R3′ P)2 PtCl2]. Syntheses and structures of [μ2-(1,2:2-η-P2){Pt(PEt3) 2}2{Pt(PEt3</s

Article abstract of DOI:10.1016/j.jorganchem.2007.04.045

Full title: Reactions of R₂P-P(SiMe₃)₂ with [(R₃^′ P)₂ PtCl₂]. Syntheses and structures of [μ₂-(1,2:2-η-P₂){Pt(PEt₃) ₂}₂{Pt(

Full text of DOI:10.1016/j.jorganchem.2007.04.045

Journal of Organometallic Chemistry 692 (2007) 3640–3648
www.elsevier.com/locate/jorganchem
Reactions of R2P–P(SiMe3)2 with ½ðR03PÞ PtCl2ꢀ.
2
Syntheses and structures of [l2-(1,2:2-g-P2){Pt(PEt3)2}2
{Pt(PEt3)2Cl}]+Clꢁ, [{(Et2PhP)2Pt}2P2], [{(p-Tol3P)2Pt}2P2]
and [(p-Tol3P)ClPt(l-PPh2)2Pt(p-Tol3P)Cl]
a
a
b
a,
*
´
Wioleta Domanska-Babul , Jaroslaw Chojnacki , Eberhard Matern , Jerzy Pikies
a
Faculty of Chemistry, Department of Inorganic Chemistry, Gdan´sk University of Technology, G. Narutowicza St. 11/12, PL-80-952 Gdan´sk, Poland
b
Institut fu¨r Anorganische Chemie, Universita¨t Karlsruhe (TH), D-76128 Karlsruhe, Germany
Received 21 December 2006; received in revised form 8 March 2007; accepted 30 April 2007
Available online 8 May 2007
Abstract
The reactions of diphosphanes R2P–P(SiMe3)2 (R = Ph, tBu, Et2N and iPr2N) with ½ðR0 PÞ PtCl2ꢀ (R0 P=Me3P, Et3P, Et2PhP, EtPh2P
3
2
3
and p-Tol3P) are very complex. The main reaction pathway is splitting of the P–P bond of the parent R2P–P(SiMe3)2 followed by
formation of ½fðR0 PÞ Ptg2P2ꢀ, R2P–PR2 and other products which have been characterized by 31P NMR spectroscopy. The molecular
3
2
structures of [{(Et2PhP)2Pt}2P2], [{(p-Tol3P)2Pt}2P2] Æ 2Et2O, [l2-(1,2:2-g-P2){Pt(PEt3)2}2{Pt(PEt3)2Cl}]+Clꢁ and [(p-Tol3P)ClPt(l-
PPh2)2Pt(p-Tol3P)Cl] have been determined by single-crystal X-ray structural analysis.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: P ligands; Diphosphorus complexes; Diphosphanes; Platinum; 31P NMR spectroscopy; X-ray structure
1. Introduction
compounds were formed in the reactions of [(dRpe)NiCl2]
with 1,2-silylated diphosphanes (SiMe3)R0P–P(SiMe3)R0
[3]. Reactions involving P(SiMe3)3 or (SiMe3)2P–P(SiMe3)2
yield [{(dRpe)Ni}2P2] [2].
The reactivity of lithium derivatives of silylphosphanes
and 1,2-silyl derivatives of diphosphanes towards
[(Et3P)2PtCl2] has been a subject of thorough studies. It
was established that [(Et3P)2PtCl2] reacts with LiP(SiMe3)2
yielding [(Et3P)Pt{l-P(SiMe3)2}2Pt(PEt3)](Pt–Pt), [(Et3P)2-
Pt{g2-(PSiMe3)2}] and [{(Et3P)2Pt}2P2] [1]. The reaction of
tBu(SiMe3)P–P(SiMe3)2 with [(Et3P)2PtCl2] yields [(Et3P)2-
Pt(g2-tBuP@PSiMe3)] and the reaction of [(Et3P)2PtCl2]
with (SiMe3)2P–P(SiMe3)2 yields [(Et3P)2Pt(g2-Me3SiP@P-
SiMe3)] together with [{(Et3P)2Pt}2P2]. The related Ni(II)
complexes with chelating tertiary phosphanes react with
R0P(SiMe3)2 under formation of side-on bonded diphosph-
ene complexes [(dRpe)Ni{g2-(R0P@PR0)}] (dRpe = R2P–
CH2–CH2–PR2, R = Et, cHex and Ph) [2]. The same
We have a long standing interest upon the chemistry of
phosphinophosphinidenes R2P–P as ligands in transition
metal complexes [4,5] and we successfully exploited
lithiated diphosphanes R2P–P(SiMe3)Li as precursors of
R2P–P ligands. We obtained [l-(1,2:2-g-tBu2P@P)-
{Zr(Cl)Cp2}2], a complex containing both a side-on and
a terminally bonded tBu2P–P ligand and [(g1-tBu2P–
P){Zr(PPhMe2)Cp2}] – the first complex with this ligand
terminally bonded [6]. We have extended our investigations
to tBu2P–PLi–PtBu2 and established the formation of [(1,2-
g-tBu2P@P–PtBu2)M(PEt3)Cl] (M = Ni, Pd) in the reac-
tions with [(Et3P)2MCl2] (M = Ni, Pd) [7] where the
triphosphorus ligand displays properties of a side-on
bonded diphosphenium cation with geometry and 31P
*
Corresponding author. Tel.: +48 58 3472622; fax: +48 58 3472694.
t
NMR properties similar to the side-on bonded Bu2P–P
E-mail address: pikies@altis.chem.pg.gda.pl (J. Pikies).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.04.045

W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
3641
ligand. Now we report our results upon the reactions of
P–P(SiMe3)2 the formation of (iPr2N)2PCl and (iPr2N)2P–
P(NiPr2)2 is significantly favoured, probably due to the
relative high stability of the (iPr2N)2P radical. The simi-
lar radical (iPr2N){(Me3Si)2N}P proved to be quite stable
[8].
diphosphanes R2P–P(SiMe3)2 with ½ðR03PÞ PtCl2ꢀ in order
2
to study whether these compounds are able to introduce
the R2P–P moiety into the Pt centre and to define the
influence of the R group on the reactivity of R2P–
P(SiMe3)2.
2.1.1. The 31P NMR studies of the mixture obtained from the
reaction of Ph2P–P(SiMe3)2 with [(R30 P)2PtCl2]
2. Results and discussion
Ph2P–P(SiMe3)2 reacts immediately at ꢁ40 °C after the
2.1. Reactivity
addition of ½ðR03PÞ PtCl2ꢀ (observable by the red color of
2
the reaction mixture). The 31P NMR monitoring of the
reaction mixtures is presented in Section 2.1.1. The main
reaction path is IV. In the reaction involving [(p-
Tol3P)2PtCl2] we isolated the phosphido-bridged complex
[(p-Tol3P)ClPt(l-PPh2)2Pt(p-Tol3P)Cl] (4). In the parent
liquor we have not observed any 31P NMR signals of 4,
probably because it is not formed in the early stages of
the reactions or because of its low solubility. The parent
liquor contains Ph2PSiMe3 resulting from splitting of the
P–P bond in the Ph2P–P(SiMe3) moiety. Thus, 4 can be
the product of a reaction of Ph2PSiMe3 with [(p-
Tol3P)2PtCl2] [9].
The outcomes of complicated reactions of R2P–
P(SiMe3)2 with ½ðR03PÞ2PtCl2ꢀ depend very strongly upon
the type of the R and R0 groups. There are many products
in the reaction mixtures and in many cases we were not able
to assign all the signals in the 31P NMR spectra. Scheme 1
shows the main pathways of these reactions.
In the pathway I the P–P bond of the parent R2P–
P(SiMe3)2 is cleaved. There are significant differences in
the product distributions between our reactions and the
reactions of [(Et3P)2PtCl2] with LiP(SiMe3)2 [1]. We have
not found P(SiMe3)3, ½ðR03PÞPtfl-PðSiMe3Þ2g2PtðPR03Þꢀ
(Pt–Pt), [(Et3P)2Pt{g2-(PSiMe3)2}] and (Me3Si)2P–
P(SiMe3)2. Thus, the formation of ½ðR03PÞ2PtfPðSiMe3Þ2g2ꢀ
in the reaction sequences seems to be very unlikely. It
seems very probable, that the R2P radical but not the
P(SiMe3)2 radical was released in the reaction sequences
of path I. It leads to phosphorus compounds (not com-
plexes) found in the reaction mixtures. This assumption is
additionally supported, because in the case of (iPr2N)2
Abbreviations: (s) – strong; (m) – medium; (w) – weak;
(v) – very, (b) – broad.
Ph2P–P(SiMe3)2
(0.48 mmol),
[(Me3P)2PtCl2]
(0.24 mmol): Ph2PH (w), Ph2P–P(SiMe3)2 (m), Ph2P–
PPh2 (m), Me3P(s), polymer at ꢁ25 ppm (b).
Ph2P–P(SiMe3)2 (0.30 mmol), [(Et3P)2PtCl2] (0.34
mmol): Ph2P–PPh2 (m), [(Et3P)3PtCl]Cl (m), [trans-
(Et3P)2PtCl2] (s), Et3P(s), A(m).
R'3P
R2PSiMe3
R2PCl
R2P-PR2
R2P-PH-PR2
R2P-P(SiMe3)-PR2
Me3SiCl
R2PH
PR'3
PR'3
PR'3
PR'3
P
R
Pt
R
R
Pt
Pt
Pt
Pt
R'3P
R'3P
PR'3
PR'3
P
P
P
+
R'3P
Pt
+
+
+
R
R'3P
R'3P
P
P
Pt(PR3)2Cl
I
R2P - P(SiMe3)2
[(R'3P)2PtCl2]
+
II
III
IV
R
R
R2P
P
PR2
P
PR'3
PR'3
P
polymeric species
+ R'3P
Pt
Pt
P
R'3P
PR'3
Scheme 1. The main pathways of the reactions R2P–P(SiMe3)2 with ½ðR03PÞ PtCl2ꢀ: I – splitting of the P–P bond of R2P–P(SiMe3)2 and formation of
2
diphosphorus complexes; II – formation of complexes with a side-on bonded phosphinophosphinidene ligand R2P–P; III – dimerization of the R2P–P
groups and formation of tetraphosphene complexes; IV – formation of polymeric species and release of tertiary phosphanes.

3642
W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
Ph2P–P(SiMe3)2
(0.91 mmol),
[(Et3P)2PtCl2]
until the addition of the diphosphane was completed. Only
after several hours at room temperature the mixture turned
yellow and the suspension started to dissolve. After a few
days the solution was clear and turned dark orange. The
31P NMR monitoring of the reaction mixtures is presented
in Section 2.1.3. The main reaction pathway is I, but prod-
ucts formed via the paths II and III are also visible. The
resonances of (iPr2N)2PCl and (iPr2N)2P–P(NiPr2)2 are
(0.45 mmol): Ph2P–PPh2 (s), Ph2P–P(SiMe3)2 (m),
Ph2P(SiMe3) (m), P(SiMe3)3 (w), Et3P (s), [{2,3-g-
(Ph2PP@PPPh2)}Pt(PEt3)2] (m), [{(Et3P)2Pt}2P2] (s).
Ph2P–P(SiMe3)2 (0.26 mmol), [(Et2PhP)2PtCl2]
(0.26 mmol): Et2PhP (vs), Ph2P–PPh2 (w),
B (w),
[{(Et2PhP)2Pt}2P2] (w), polymer at +10 ppm (b), Ph2PCl
(m).
Ph2P–P(SiMe3)2 (0.32 mmol), [(Et2PhP)2PtCl2]
very strong. 0 In case of
a
molar ratio (iPr2N)2P–
(0.18 mmol): Et2PhP (s), Ph2P–PPh2 (w),
B
(w),
P(SiMe3)2:½ðR3PÞ2PtCl2ꢀ ðR03P ¼ Et2PhP;p-Tol3PÞ of 2:1 it
is possible to isolate the related diphosphorus Pt complexes
1 and 2 as crystals in acceptable yield. With a molar ratio
of 1:1 and R03P ¼ Et3P, the ionic complex [l2-(1,2:2-g-
P2){Pt(PEt3)2}2{Pt(PEt3)2Cl}]+Clꢁ (3) could be isolated in
a fairly good yield (Scheme 3). In the reaction solution we
have not observed any 31P NMR signals which can be attrib-
uted to 3, presumably because this compound was formed in
the final stages of reactions according to Scheme 3, or
because of dynamic equilibria which can alter the 31P
NMR spectrum of this compound.
[{(Et2PhP)2Pt}2P2] (w), Polymer at +10 ppm (b),
Ph2P(SiMe3) (w), [(2,3-g-Ph2PP@PPPh2)Pt(PPhEt2)2] (m),
Ph2P–P(SiMe3)2 (s), Ph2PCl (m).
Ph2P–P(SiMe3)2(0.22 mmol),
(0.21 mmol): EtPh2P (vs), [{(EtPh2P)2Pt}2P2] (m), polymer
at +10 ppm (b).
Ph2P–P(SiMe3)2 (0.31 mmol), [(EtPh2P)2PtCl2]
(0.16 mmol): EtPh2P (vs), [{(EtPh2P)2Pt}2P2] (m), polymer
at +10 ppm (b), Ph2P–P(SiMe3)2 (s), Ph2P(SiMe3) (m).
Ph2P–P(SiMe3)2 (0.20 mmol), [(p-Tol3P)2PtCl2]
(0.22 mmol): p-Tol3P (vs), polymer at +20 ppm (b).
Ph2P–P(SiMe3)2 (0.43 mmol), [(p-Tol3P)2PtCl2]
(23 mmol): p-Tol3P (vs), polymer at +20 ppm (b), Ph2P–
P(SiMe3)2 (s), Ph2P(SiMe3) (m).
[(EtPh2P)2PtCl2]
In the case of R0 P ¼ Et3P or Et2PhP, 31P NMR examin-
3
ations of the reaction mixtures indicated two AA0XX0 spin
systems (C and E). These reactions yield additionally some
Pt complexes with five P atoms in the molecule (D, F, G, H,
I, K) and a complex compound with four P atoms in the
molecule (L).
2.1.2. The 31P NMR studies of the mixture obtained from the
reaction of (Et2N)2P–P(SiMe3)2 with [(R03P)2PtCl2]
(iPr2N)2P–P(SiMe3)2 (0.28 mmol), [(Et3P)2PtCl2]
(0.28 mmol): (iPr2N)2PCl (vs), (iPr2N)2P–P(NiPr2)2 (s),
(iPr2N)2PH (m), [trans-(Et3P)2PtCl2] (m), [cis-(Et3P)2PtCl2]
(m), Et3P (m), C (m), D (m), (iPr2N)2P–PH–P(NiPr2)2 (m),
(Et2N)2P–P(SiMe3)2
reacts
more
slowly
with
½ðR03PÞ2PtCl2ꢀ than Ph2P–P(SiMe3)2 (about 1 day). The
31P NMR monitoring of the reaction mixtures is presented
in Section 2.1.2. The main reaction path is I.
[(2,3-g-{(iPr2N)2)P–P@P–P(NiPr2)2}Pt(PEt3)2]
(w),
(Et2N)2P–P(SiMe3)2 (0.19 mmol), [(Et2PhP)2PtCl2]
(0.20 mmol): Et2PhP (s), (Et2N)3P (s), [{(Et2PhP)2Pt}2P2]
(s). We were not able to resolve many weak signals in the
range from +37 to +22 ppm without Pt satellites.
(Et2N)2P–P(SiMe3)2 (0.35 mmol), [(Et2PhP)2PtCl2]
(0.19 mmol): Et2PhP (s), (Et2N)2P–P(NEt2)2 (m),
[{(Et3P)2Pt}2P2] (w). The mixture appears to be very com-
plex. We were not able to attribute many signals with Pt
satellites especially in the range of 30–0 ppm (overlaps
and higher order spectra).
(iPr2N)2P–P(SiMe3)2 (0.34 mmol), [(Et3P)2PtCl2]
(0.17 mmol): [{(Et3P)2Pt}2P2] (vs), (iPr2N)2P–P(NiPr2)2
(s), (iPr2N)2PCl (s), [(2,3-g-{(iPr2N)2)P–P@P–P(NiPr2)2}
Pt(PEt3)2] (m), (iPr2N)2P–P(SiMe3)H (w), (iPr2N)2P–PH–
P(NiPr2)2 (w), C (w), D (w).
[{(Et2PhP)2Pt}2P2]
(s),
(Et2N)2P–P(SiMe3)2
(m),
(Et2N)2P–P(SiMe3)H (m), (Et2N)3P (w). Many weak sig-
nals in the range from +37 to +24 ppm without Pt satellites
we were not able to resolve.
(Et2N)2P–P(SiMe3)2 (0.19 mmol), [(EtPh2P)2PtCl2]
(0.19 mmol): [{(EtPh2P)2Pt}2P2] (s), P(NEt2)3 (m),
PCl(NEt2)2 (w), EtPh2P (w). Many weak signals in the
range from +37 to +15 ppm without Pt satellites we were
not able to resolve.
(Et2N)2P–P(SiMe3)2 (0.32 mmol), [(EtPh2P)2PtCl2]
(0.16 mmol): [{(EtPh2P)2Pt}P2] (s), EtPh2P(w), (Et2N)2P–
P(SiMe3)2 (s), (Et2N)2P–P(SiMe3)H (m), (Et2N)2P–
P(SiMe3)–P(NEt2)2 (w), P(NEt2)3 (w). Many weak signals
in the range from +37 to +21 ppm without Pt satellites
we were not able to resolve.
(iPr2N)2P–P(SiMe3)2 (0.25 mmol), [(Et2PhP)2PtCl2]
(0.25 mmol): (iPr2N)2PCl (vs), Et2PhP (s), (iPr2N)2P–
P(NiPr2)2 (s), [{(Et2PhP)2Pt}2P2] (s), (iPr2N)2PH (m),
(iPr2N)2P–PH–P(NiPr2)2 (m), [(2,3-g-{(iPr2N)2)P–P@P–
P(NiPr2)2}Pt(PPhEt2)2] (w), E (m), F (w), G (w). We have
not resolved some signals with Pt satellites in the range
of 18–2 ppm (overlaps and higher order spectra).
(iPr2N)2P–P(SiMe3)2 (0.39 mmol), [(Et2PhP)2PtCl2]
(0.18 mmol): (iPr2N)2P–P(NiPr2)2 (vs), [{(Et2PhP)2Pt}2P2]
(m), (iPr2N)2PCl (m), (iPr2N)2PH (w), (iPr2N)2P–PH–
P(NiPr2)2 (m), (iPr2N)2P–P(SiMe3)2 (m), Et2PhP(m), (iPr2N)2
P–P(SiMe3)H (w), (iPr2N)2P–P(SiMe3)–P(NiPr2)2 (w).
(iPr2N)2P–P(SiMe3)2 (0.25 mmol), [(EtPh2P)2PtCl2]
(0.25 mmol): [{(EtPh2P)2Pt}2P2] (s), (iPr2N)2PCl (s), [cis-
(EtPh2P){(iPr2N)2PH}PtCl2] (m), [cis-(EtPh2P)2PtCl2]
(m), (iPr2N)2P–PH–P(NiPr2)2 (m), EtPh2P (m), (iPr2N)2P–
P(SiMe3)H (w), H (w).
2.1.3. The 31P NMR studies of the mixture obtained from the
reaction of (iPr2N)2P–P(SiMe3)2 with [(R0 P)2PtCl2]
3
The reactions of (iPr2N)2P–P(SiMe3)2 with ½ðR0 PÞ PtCl2ꢀ
3
2
were very slow. We did not observe any change in the mixture

W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
3643
(iPr2N)2P–P(SiMe3)2 (0.18 mmol), [(EtPh2P)2PtCl2]
(0.09 mmol): (s),
(iPr2N)2P–P(NiPr2)2 (iPr2N)2P–
P(SiMe3)H (s), (iPr2N)2PCl (s), EtPh2P (s), (iPr2N)2P–
PH–P(NiPr2)2 (iPr2N)2P–P(SiMe3)2
(m), (m),
[{(EtPh2P)2Pt}2P2] (w).
2.2. 31P NMR studies of reaction products
The 31P NMR data of the known compounds are given
in the supplementary material. The 31P{1H} NMR data for
the diphosphorus complexes ½fðR03PÞ2Ptg2P2ꢀ are summa-
rized in Table 1, for the tetraphosphene complexes
½ðR03PÞ2Ptð2; 3-g-R2PAP@PAPR2Þꢀ in Table 2. Table 3
showing the data for Pt complexes with five P atoms (not
completely) and Table 4 showing the data for Pt complexes
with four P atoms are in the supplementary material. The
31P{1H} NMR data for the unknown compounds A–E
are in the supplementary material.
(iPr2N)2P–P(SiMe3)2 (0.25 mmol), [(p-Tol3P)2PtCl2]
(0.25 mmol): (iPr2N)2P–P(NiPr2)2 (vs), (iPr2N)2PCl (s),
(iPr2N)2P–P(SiMe3)H (s), (iPr2N)2P–PH–P(NiPr2)2 (s), p-
Tol3P (s), [{(p-Tol3P)2Pt}2P2] (m), [cis-(p-Tol3P){(iPr2N)2
PH}PtCl2] (m), [(p-Tol3P)2Pt{g2-(iPr2N)2P–P}] (w), I (w),
polymer at +25 ppm (b,w).
(iPr2N)2P–P(SiMe3)2 (0.50 mmol), [(p-Tol3P)2PtCl2]
(0.22 mmol): (iPr2N)2P–P(NiPr2)2 (s), (iPr2N)2PCl (s),
(iPr2N)2P–P(SiMe3)H (s), (iPr2N)2P–PH–P(NiPr2)2 (s), p-
Tol3P (s), [{(p-Tol3P)2Pt}2P2] (m), [cis-(p-Tol3P){(iPr2N)2
PH}PtCl2] (m), [(p-Tol3P)2Pt{g2-(iPr2N)2P–P}] (w),
(iPr2N)2P–P(SiMe3)2 (m), I (w), K (w), L (w), polymer at
+25 ppm (b,w).
2.3. X-ray crystallographic studies
Complex 1 crystallized in the orthorhombic system,
space group Pbca. The molecular structure of [{(Et2PhP)2-
Pt}2P2] (1) is shown in Fig. 1. Complex 2 crystallized in the
monoclinic system, space group C2/c. The molecular struc-
ture of [{(p-Tol3P)2Pt}2P2] Æ 2Et2O (2) is shown in Fig. 2.
The structures of 1 and 2 are similar to that of [{(depe)-
Ni}2P2] [2]. The molecule of 1 consists of two distorted
square-planar arrangements P1–P2–P5–P6–Pt1 and P3–
P4–P5–P6–Pt2 respectively, almost perpendicular to each
other, which form a ‘‘roof’’ framework. The geometry of
such a PtP2(MLn)2 system (MLn 14 VE) can be viewed as
a result of a p donor interaction of four electrons of a P2
molecule to two d10ML2 metal centers. The dihedral angle
between these planes (99.75°) illustrates the approximate
orthogonality of the two p bonds in the triple bond of
the P2 unit. The P5–P6 distance in the P2 group (214.1
pm) lies between the values for a P@P bond in sterically
protected diphosphenes (ꢂ203 pm) [11] and the typical val-
ues for a single P–P bond (ꢂ 220 pm). The PtP4 systems
(P1–P2–Pt1–P5–P6) and (P3–P4–Pt2–P5–P6) are almost
planar, with a root mean square deviation of fitted atoms
from planarity of 5.79 pm and 7.55 pm, respectively.
The asymmetric unit of 2 contains half of the complex
molecule and two halves of diethyl ether molecules. The
centre of the diphosphorus ligand sits on a twofold rotation
axis (Wyckoff position e) [12]. The dihedral angle between
the planes (Pt1–P3–P3#1) and (Pt1#1–P3–P3#1) is a bit
larger than in the case of 1 and equals to 104.37(7)°, prob-
ably due to packing effects. The platinum atom Pt1 adopts
a distorted square-planar coordination with a root mean
square deviation of fitted atoms of 6.60 pm from the mean
plane (P1–P2–Pt1–P3–P3#1). The other plane has the same
geometry as both are symmetry equivalent. The bond
2.1.4. The 31P NMR studies of the mixture obtained from the
t
reaction of Bu2P–P(SiMe3)2 with [(Et2PhP)2PtCl2]
The
reaction
between
tBu2P–P(SiMe3)2
and
[(Et2PhP)2PtCl2] was very slow. After several hours at
room temperature the mixture turned yellow and the sus-
pension started to dissolve. After a few days the mixture
became transparent and turned dark orange. The 31P
NMR examinations of these reactions are listed in Section
2.1.4. These reactions yield products consistent with path-
ways I and II and additionally yield two complexes with
four P atoms (M and N). The pathway II is visible only
for R2P–P(SiMe3)2 with sterically demanding R groups
i
(R = tBu or Pr2N), but pathway I clearly predominates.
It is probably a substitution of Cl in ½ðR03PÞ2PtCl2ꢀ by
means of R2P–P(SiMe3)2 with two eliminations of Me3SiCl
molecules (Scheme 2).
31P{1H} NMR of M is in accord with the proposed for-
mula for the intermediate complex (*). In the case of
R = iPr2N and R30 P ¼ p-Tol3P there is such a conformity
for compound L (see supplementary material).
tBu2P–P(SiMe3)2 (0.22 mmol), [(Et2PhP)2PtCl2]
t
(0.21 mmol): [{(Et2PhP)2Pt}2P2] (s), Bu2PH (s), Et2PhP
t
t
(s), Bu2PCl (w), [(Et2PhP)2Pt(g2-tBu2P–P)] (m), Bu2P–
PtBu2 (w), M (w), N (w), P(PtBu2)3 (w).
tBu2P–P(SiMe3)2 (0.47 mmol), [(Et2PhP)2PtCl2]
t
(0.23 mmol): [{(Et2PhP)2Pt}2P2] (s), Bu2PH (s), Et2PhP
t
t
(s), Bu2PCl (w), [(Et2PhP)2Pt(g2-tBu2P–P)] (m), Bu2P–
PtBu2 (w), M (w), N (w), Bu2P–P(SiMe3)2 (vs), Bu2P–
t
t
P(SiMe3)H (m), P(PtBu2)3 (w).
SiMe3
Et2PhP
Et2PhP
Me3Si
SiMe3
tBu
P
P
Et2PhP
Et2PhP
Cl
Cl
*
-Me3SiCl
tBu
tBu
Et2PhP
Et2PhP
P
P
P
Pt
tBu
-Me3SiCl
Pt
+
P
Pt
tBu
tBu
Cl
Scheme 2. Proposed reaction sequence on pathway II.

3644
W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
Table 1
31P{1H} NMR data of ½fðR30 PÞ2Ptg2P2ꢀ: P1,2,3,4 = R03P, P1,2 = P2
dP1,2,3,4 (1JPt–P
)
dP5,6 (1JPt–P
)
Peak distance
[{(Et3P)2Pt}2P2] [1]
[{(Et2PhP)2Pt}2P2] (1)
[{(EtPh2P)2Pt}2P2]
pst 10.7 (3487)
pst 11.1 (3506)
pst 16.5 (3588)
pst 21.6 (3602)
psq 47.2 (0–5)
psq 48.7 (0–5)
psq 55.7 (0–5)
psq 99.0 (27)
22.9
22.8
22.9
25.2
[{(p-Tol3P)2Pt}2P2] (2)
AA0XX0A00A000 – pattern, pst – pseudotriplet; psq – pseudoquintet, peak distance – the apparent coupling constants in the pseudo multiplets (see Section
2.4).
Table 2
31P{1H} NMR data of ½ðR0 P5; 6Þ Ptð2; 3-g-R2P1–P2@P3–P4R2Þꢀ
3
2
dP1,4 (1JPt–P
)
dP2,3(1JPt–P
)
dP5,6 (1JPt–P
)
[(Et3P)2Pt(2,3-g-Ph2PP@PPPh2)]
ꢁ12.3 (46)
ꢁ12.1 (38)
87. 0 (55)
85.9 (62)
ꢁ36.4 (284.6)
ꢁ31.5 (289,0)
ꢁ4.4 (229.5)
ꢁ4.4 (242)
18.8 (3262)
16.0 (3267)
16.5 (3254)
16.8 (3265)
[(Et2PhP)2Pt(2,3-g-Ph2PP@PPPh2)]
[(Et3P)2Pt(2,3-g-(iPr2N)2PP@PP(NiPr2)2}]
[(Et2PhP)2Pt{2,3-g-(iPr2N)2PP@PP(NiPr2)2}]
AA0MM0XX0 – pattern, for [(R3P)2Pt[(2,3-g-tBu2PP)@PPtBu2]] (R3P = Ph3P, EtPh2P) see [10].
length between the phosphorus atoms in the bridging P2
unit is short (211.0(6) pm), similar as in 1.
Compound 3 crystallized in the monoclinic system
(space group P21/c). The molecular structure of [l2-
(1,2:2-g-P2){Pt(PEt3)2}2{Pt(PEt3)2Cl}]+Clꢁ (3) is shown
in Fig. 3.
[{(Et3P)2Pt}2P2] is coordinated terminally to the
(Et3P)2PtCl+ moiety via a lone pair of the P2 group. This
additional terminal coordination exerts only minor influ-
ence on the geometry of the ‘‘roof’’ skeleton P7–P8–Pt3–
P2–P1–Pt1–P3–P4. The distance P1–Pt2 of 234.3(4) pm is
relatively long. It is in the range typical for [trans-
(PR3)2PtCl2]. For terminally bonded phosphaalkene [cis-
PtCl2(PEt3)(g1-MesP-CPh2)] Æ CHCl3 [13] the related Pt–P
distance is much shorter (219.9 pm). The P1–P2 distance
of 212.9(5) pm is similar as in 1 or in 2. The coordination
Fig. 1. The molecular structure of [{(Et2PhP)2Pt}2P2] (1). Displacement
ellipsoids 50%, hydrogen atoms not shown.
P1–Pt2 causes
a
widening of the torsion angle
Fig. 2. The molecular structure of [{(p-Tol3P)2Pt}2P2] Æ 2Et2O (2). Dis-
placement ellipsoids 50%, two solvent Et2O molecules and hydrogen
atoms not shown.
Fig. 3. Molecular structure of [l2-(1,2:2-g-P2){Pt(PEt3)2}2{Pt(PEt3)2-
Cl}]+Clꢁ (3), showing non-carbon atoms labeling. Displacement ellipsoids
50%, hydrogen atoms not shown.

W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
3645
reported phosphido-bridged complex of Pt(II), similar to
[(tBu2PH)ClPt(l- PPh2)2Pt(tBu2PH)Cl] [15].
The molecule is centrosymmetric with a centre of sym-
metry placed inside the Pt2P2 ring. The Pt1–P2–Pt1a–P2a
ring is planar with a Pt1–Pt1a distance of 351.8 pm which
indicates no Pt–Pt bonding. Cl1 and Cl1a are in trans posi-
tion imposed by the symmetry center. The coordination
environment of Pt is planar, the sum of valence angles
around Pt1 is 359.9°. The Pt1–P2 bond of 233.2(2) pm is
remarkably longer than Pt1–P2a (227.0(2) pm), which illus-
trates the significant trans effect of (p-Tol)3P compared to
the Clꢁ ligand.
2.4. The 31P NMR spectra of 1–3
Fig. 4. Molecular structure of [(p-Tol3P)ClPt(l-PPh2)2Pt(p-Tol 3P)Cl] (4).
Displacement ellipsoids 50%, hydrogen atoms not shown, symmetry code
a: 2 ꢁ x, 1 ꢁ y, ꢁz.
Compounds 1 and 2 are AA0XX0A00A000 systems (Table
1), and their 31P{1H} NMR spectra are very similar to
[{(Et3P)2Pt}2P2] [1]. Both the pseudo quintet and the
pseudo triplet have small and partly hidden lines of satellite
spectra in the signal basis, but only the pseudo triplet
shows satellite peaks with 1JPt–P of the usual size. The peak
distances in the pseudo multiplets give the mean value
Pt1–P1–P2–Pt3 (110.41°) as compared to 99.13° in 1. The
Pt2–P6 distance of 236.5(4) pm is distinctly longer than
Pt2–P5 (224.2(4) pm) due to a trans effect of the P1–Pt2
bond. The distance Pt1–Pt3 (347.2 pm) clearly indicates
no Pt–Pt bonding. For Pt(I) dimers with bridging phosph-
ido ligands Pt–Pt distances of about 260 pm were reported
[14].
(2JAX + 2JA X)/2 and are not coupling constants. These
0
are strongly correlated and therefore cannot be directly
evaluated. The line width of the peaks in the main multi-
plets are about 4–5 Hz which is just the same order of
[(p-Tol3P)ClPt(l-PPh2)2Pt(p-Tol3P)Cl] (4) crystallized in
ꢀ
the triclinic system, space group P1 (Fig. 4). It is the second
..
+
PEt3
PEt3
Et3P
Et3P
P
..
PEt3
PEt3
Cl
Cl
Et3P
Et3P
Pt
P
Pt
+
Pt
Cl-
Pt
Pt
P
PEt3
PEt3
P
..
Cl Pt PEt3
PEt3
Scheme 3. The formation of complex 3.
Fig. 5. Temperature dependant 31P{1H} NMR spectra of 3 in THF–C6D6 solution; recorded (a) on Bruker AMX300 and (b) on Bruker Av400.

3646
W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
magnitude as in peaks of some phosphanes also present in
the samples.
proceed under formation of these complexes in a fairly
good yield [17].
The formation of 3 can be seen as a coordination of
[{(Et3P)2Pt}2P2] via the lone electron pair of the P2 ligand
to [cis-(Et3P)2PtCl2] according to Scheme 3.
4. Experimental
The 31P{1H} NMR spectrum of a solution of crystals of
3 in THF and C6D6 contained very small amounts of
unknown Pt–P compounds, however no signals of [cis-
(Et3P)2PtCl2] nor of [{(Et3P)2Pt}2P2] could be identified.
Quite contrary to them and to 1 and 2, the main signals
in this spectrum have line widths of about 60–90 Hz at
ambient temperature. No fine structure is resolved, just
two ‘‘doublets’’ accompanied by 195Pt satellites and two
additional very broad signals without 195Pt satellites can
be recognized. These ‘‘doublets’’ must be assigned to P3
and P7 as well as to P4 and P8 of 3, and the broad signals
to P1 and P2. The peaks for P5 and P6 must be hidden by
the large ‘‘doublets’’. Anyway, it is not possible to assign
the spectrum unequivocally to the structure of 3.
In order to identify the multiplets and to test for
dynamic processes involving 3, spectra on two spectrome-
ters with different basis frequencies and at various temper-
atures were recorded (Fig. 5). At ꢁ70 °C and ꢁ30 °C the
resonances of P1 (ꢂꢁ143 ppm) and P2(ꢂ+65 ppm) slightly
resolve to multiplet patterns, however the line widths in the
other parts of the spectra do not really narrow. At +50 °C
the multiplet at about ꢁ2.5 ppm gets somewhat better
resolved, but already at +65 °C this is lost again, probably
due to a considerable amount of decomposition of 3. There
is also some minor temperature shift over the observed
range. It was not possible to freeze any isomers of 3 nor
to reach a sufficiently fast process to get narrow line spec-
tra. It can be assumed, but so far not verified, that the
Pt3(PEt3)2Cl unit migration between P1 and P2 of 3 is at
least part of the dynamic process.
4.1. General comments
All reactions and manipulations were carried out under
an atmosphere of ultra-high purified argon employing stan-
dard Schlenk techniques. Solvents were purified, dried and
distilled prior to use from dark blue potassium or sodium
diphenyl ketyl solution [18]. The known diphosphanes
R2P–P(SiMe3)2 (R = Ph, tBu, Et2N) were prepared accord-
ing to published methods [19–21], (iPr2N)2P–P(SiMe3)2 was
prepared according to the published method for (Et2N)2P–
P(SiMe3)2 [21]. ½ðR03PÞ2PtCl2ꢀ (R03P = Me3P, Et3P, Et2PhP,
EtPh2P and p-Tol3P) were prepared according to proce-
dures described in [22].
31P NMR spectra were recorded on Bruker AC250, Bru-
ker Av400, Bruker AMX300 and Varian Unity+ 500 spec-
trometers (external standard 85% H3PO4) mainly at
ambient temperature. For compound 3 variable tempera-
ture NMR studies were performed.
All reactions of R2P–P(SiMe3)2 with ½ðR03PÞ2PtCl2ꢀ were
carried out in the same way. Therefore, only those runs
which resulted in well defined crystalline products are
described more detailed.
4.2. Synthesis of[{(Et2PhP)2Pt}2P2] (1)
Compound 1 was obtained in a reaction between
(iPr2N)2P–P(SiMe3)2 and [(Et2PhP)2PtCl2] in the molar
ratio of 2:1. To a stirred slurry of [(Et2PPh)2PtCl2]
(107 mg, 0.18 mmol) in THF (2 ml) at ꢁ40 °C was slowly
dropped (iPr2N)2P–P(SiMe3)2 (159 mg, 0.39 mmol) dis-
solved in THF (2 ml). The mixture was allowed to warm
to room temperature and was stirred for 4 days. The sus-
pension dissolved and the solution turned orange. The
solution was examined with 31P NMR, then evaporated
under vacuum (1 mTorr, 3 h). The residue was dissolved
in pentane (3 ml) and filtered. After one month at +4 °C
3. Conclusions
The silylated diphosphanes R2P–P(SiMe3)2 react with
complexes of platinum ½ðR03PÞ2PtCl2ꢀ in a complex way.
The main path is connected with a splitting of the P–P
bond of the R2P–P(SiMe3) moiety leading in a sequence
of reactions (including recombination steps of building
blocks) to diphosphorus complexes of platinum(0) of the
type [(L2Pt)2P2]. 31P NMR examinations of the reaction
solutions indicate a formation of many other compounds
resulting from the reactions of the released R2P fragment
(probably radical), i.e. R2P–PR2, R2PCl, R2PH, R2PSiMe3,
½ðR03PÞClPtðl-PPh2Þ2PtðPR30 ÞClꢀ, R2P–P(SiMe3)–PR2, and
R2P–PH–PR2, (Et2N)3P and P(PtBu2)3.
In those reactions of diphosphanes R2P–P(SiMe3)2,
where R are sterically demanding groups like tBu or iPr2N,
with ½ðR03PÞ2PtCl2ꢀ, we establish a formation of phosphino-
phosphinidene complexes ½ðR03PÞ2Ptðg2-R2P–PÞꢀ [16] in
poor yield together with complex mixtures of other com-
pounds. This is a striking difference as compared to the
reactions of R2P–P(SiMe3)Li with ½ðR03PÞ2PtCl2ꢀ which
small pale-yellow crystals of
1
deposited (33 mg,
0.030 mmol). 1 is for short time stable in air. 31P NMR
(see Table 1). Anal. Calc. for C40H60P6Pt2: C, 43.02; H,
5.42. Found: C, 43.31; H, 5.57%.
4.3. Synthesis of [{(p-Tol3P)2Pt}2P2] Æ 2Et2O (2)
Compound 2 is a product of the reaction of (iPr2N)2P–
P(SiMe3)2 with [(p-Tol3P)2PtCl2] in a molar ratio of 2:1. To
a stirred slurry of [(p-Tol3P)2PtCl2] (150 mg, 0.22 mmol) in
THF (1.5 ml) at ꢁ40 °C was slowly dropped (iPr2N)2P–
P(SiMe3)2 (204 mg, 0.50 mmol) dissolved in THF
(1.5 ml). The mixture was allowed to warm to room tem-
perature and stirred for 3 days. The suspension dissolved
and the solution turned dark brown. The solution was
examined with 31P NMR, then evaporated under vacuum

W. Doman´ska-Babul et al. / Journal of Organometallic Chemistry 692 (2007) 3640–3648
3647
(1 mTorr, 5 h). The residue was dissolved in diethyl ether
(5 ml), filtered and evaporated to 1 ml. After one month
at +4 °C a small amount of thin pale-yellow needles of 2
deposited. Compound 2 is for short time stable in air. 31P
NMR see Table 1.
tion Ltd. Numerical absorption correction based on the
multi-faceted crystal shape with empirical scaling was
applied (CrysAlis RED, Oxford Diffraction [23,24]). Details
of crystal data, data collection and refinement are summa-
rized in Table 6 (supplementary material). The structures
were solved by direct methods using the SHELX-97 program
package [25,26] and refined with full-matrix least-squares
on F2. All atoms, excluding hydrogen, were refined with
anisotropic displacement ellipsoids. Carbon atom C33 from
the ethyl group in compound 1, due toits tendency to become
non-positively defined, had to be refined isotropically. In the
case of 2, solvating diethyl ether molecules were refined using
an isotropic model with constrained bond lengths. Hydrogen
atoms were positioned geometrically and refined as riding on
their heavy atoms.
4.4. Synthesis of [l2-(1,2:2-g-
P2){Pt(PEt3)2}2{Pt(PEt3)2Cl}]+Clꢁ (3)
Compound 3 is a product of the reaction of (iPr2N)2P–
P(SiMe3)2 with [(Et3P)2PtCl2] in a molar ratio of 1:1. To a
stirred slurry of [(Et3P)2PtCl2] (144 mg, 0.28 mmol) in THF
(2 ml) at ꢁ40 °C was slowly dropped (iPr2N)2P–P(SiMe3)2
(114 mg, 0.28 mmol) dissolved in THF (2 ml). The mixture
was allowed to warm to room temperature and stirred for 4
days. The suspension dissolved and the solution turned
orange. The solution was examined by 31P NMR (very
complex mixture), then evaporated under vacuum
(1 mTorr, 1 h). The residue was dissolved in pentane
(5 ml), filtered and concentrated to ꢂ 1 ml. After 2 months
at ambient temperature big, almost colorless crystals of 3
were obtained (ꢂ50 mg, 0.035 mmol). Compound 3 is
moderately stable in air.
Acknowledgements
W.D.-B. and J.P. thank the Polish State Committee of
Scientific Research (project No. 1 T09A 148 30) for finan-
cial support.
Appendix A. Supplementary material
1H NMR (THF–C6D6, 295 K): 1.99–1.86 m, overlapped
PCH2CH3; 1.02–0.92 m, overlapped PCH2CH3. 31P NMR
CCDC 609987, 609988, 616584 and 616585 contain the
supplementary crystallographic data for compounds 1–4.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-
mail: deposit@ccdc.cam.ac.uk.
1
(THF–C6D6, 203 K): 63.4, m, P1, JPt–P ꢂ 0; ꢁ2.3, m, P3,
1
1
P7, JPt1–P3 ꢂ 2780; ꢁ2.3, m, P5, JPt3–P5 ꢂ 2700; ꢁ7.8,
1
1
m, P4, P8, JPt1–P4 ꢂ 2300; ꢁ10.2, m, P5, JPt3–P5 ꢂ 2700;
1
ꢁ142.9, m, P2, JPt1–P2 ꢂ 0; small signals at 23.11 ppm (s,
1
1
no JP–H, JPtꢁP = 2710 Hz) not detected in the reaction
1
1
mixture and at 20.22 ppm (d, 22.8 Hz, no JP–H, JPt–P
=
2605 Hz) detected in the reaction mixture. Anal. Calc. for
C36H90P8Pt3Cl2: C, 30.30; H, 6.36. Found: C, 30.62; H,
6.12%.
The 31P NMR data of the discussed compounds and
details of the crystal structure determinations of 1–4 are
available from the authors on request. Supplementary data
associated with this article can be found, in the online ver-
sion, at doi:10.1016/j.jorganchem.2007.04.045.
4.5. Synthesis of [(p-Tol3P)ClPt(l-PPh2)2Pt(p-Tol3P)Cl]
(4)
References
Compound 4 is a product of the reaction Ph2P–
P(SiMe3)2 with [(p-Tol3P)2PtCl2] in molar ratio 1:1. To a
stirred slurry of [(p-Tol3P)2PtCl2] (150 mg, 0.22 mmol) in
THF (1.5 ml) at ꢁ40 °C was slowly dropped Ph2P–
P(SiMe3)2 (74 mg, 0.204 mmol) dissolved in THF
(1.5 ml). After warming up the mixture to room tempera-
ture it turned immediately orange and the suspension dis-
solved. After 2 days the solution was examined with 31P
NMR, then evaporated under vacuum (1 mTorr, 5 h).
The residue was dissolved in toluene (5 ml), filtered and
evaporated to 0.5 ml. After one week at ambient tempera-
ture 3 ml pentane was added to the toluene solution. After
4 months a small amount of very thin colorless crystals of 4
was obtained.
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