Specific insertion reactions of a germylene, stannylene and plumbylene into the unique P-P bond of the hexaphospha-pentaprismane cage, P6C 4tBu4: Crystal and molecular structures of P6C4tBu4ER2 (E = Ge, Sn, R = N(SiMe3)2; E = Pb, R = (C6H 3 ...

Article abstract of DOI:10.1039/b800458g

Full title: Specific insertion reactions of a germylene, stannylene and plumbylene into the unique P-P bond of the hexaphospha-pentaprismane cage, P₆C ₄^tBu₄: Crystal and molecular structures of P₆C₄^tBu₄ER₂ (E = Ge, Sn, R = N(SiMe₃)₂; E = Pb, R = (C₆H ₃(NMe₂)₂ -2,6). Treatment of the cage compound P₆C₄ ^tBu₄ with M{N(SiMe₃)₂}₂ (M = Ge or Sn) or Pb(C₆H₃(NMe₂) _2-2,6) at room temperature results in their specific insertion into the P-P bond connecting the two 5-membered P₃C₂ ^tBu₂ rings. The products were fully characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies. The Royal Society of Chemistry.

Full text of DOI:10.1039/b800458g

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Specific insertion reactions of a germylene, stannylene and plumbylene into
t
the unique P–P bond of the hexaphospha-pentaprismane cage, P6C4 Bu4:
t
Crystal and molecular structures of P6C4 Bu4ER2 (E = Ge, Sn, R =
N(SiMe3)2; E = Pb, R = (C6H3(NMe2)2 -2,6)†
Mahmoud M. Al-Ktaifani, Peter B. Hitchcock, Michael F. Lappert, John F. Nixon* and Philip Uiterweerd
Received 11th January 2008, Accepted 4th March 2008
First published as an Advance Article on the web 4th April 2008
DOI: 10.1039/b800458g
t
Treatment of the cage compound P6C4 Bu4 with M{N(SiMe3)2}2 (M = Ge or Sn) or
Pb(C6H3(NMe2)2–2,6) at room temperature results in their specific insertion into the P–P bond
t
connecting the two 5-membered P3C2 Bu2 rings. The products were fully characterised by multinuclear
NMR spectroscopy and single crystal X-ray diffraction studies.
Introduction
Organo-phosphorus cage compounds have received considerable
attention in recent years, the two major synthetic routes involv-
ing oxidative coupling of the polyphospholyl anions PnCnR5−n
(n = 2, 3) and thermal or metal-mediated oligomerisation of
t
1,2
≡
phosphaalkynes, P CR, (R = Bu ). Cages involving tetramers,
t
≡
pentamers and hexamers of P CBu are shown in Fig. 1 and
cages containing one or more additional hetero-atoms such as
antimony,3 silicon,4 germanium,4 sulfur,5 selenium5 and tellurium5
are shown in Fig. 2.
The chalcogen substituted organo-phosphorus systems
t
P6C4 Bu4E (E = S, Se Te) were easily prepared as shown in Fig. 3, by
an unusually facile and specific insertion of the chalcogen into the
P–P bond joining the two 5-membered rings of the hexaphospha-
pentaprismane 1.5 Theoretical calculations on P6C4H4, at the
HF/6-31G*//B3LYP/6-31G level, show that the central P–P
bond is not only involved in both the HOMO and LUMO orbitals.
but also in HOMO − 1, strongly suggesting that this bond is most
likely to be involved in bond cleavage reactions of 1.
It was therefore of interest to examine the generality of this type
of specific insertion reaction, by studying the interaction of 1 with
other iso-electronic species such as germylenes, stannylenes and
plumbylenes, MR2 (M = Ge, Sn or Pb).
Fig. 2 Some organophosphorus cages containing other heteroatoms.
Results and discussion
t
Treatment of P6C4 Bu4 1 with the stable germylene and stannylene
M{N(SiMe3)2}2, (M = Sn or Ge), or the plumbylene PbAr2
(Ar = 2,6-(NMe2)2C6H3)6,7 in hexane at room temperature gave
the expected products 2, 3 and 4 via insertion of the MR2 fragment
into the unique P–P bond joining the two 5-membered rings
Department of Chemistry, School of Life Sciences, University of Sussex,
Brighton, Sussex, UK BN1 9QJ
† CCDC reference numbers 674809–674812. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b800458g
t
≡
Fig. 1 Cage structures of the tetramer, pentamer and hexamer of the phosphaalkyne, P CBu .
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Compounds 2–4 all have a 2-fold rotational axis, resulting in
t
only three different P environments and two Bu environments.
ꢀ
Thus PA and PA are chemically equivalent (but magnetically non-
ꢀ
ꢀ
equivalent), as are the pairs PB and PB , and PC and PC . The
31P{ H} NMR spectra of 2–4, which are shown in Fig. 4, 6 and 8,
1
are typical for AAꢀMMꢀXXꢀ spin systems (compounds 2 and 4 also
exhibit additional coupling to 119Sn and 207Pb nuclei respectively).
Examples of this type of spin system involving six phosphorus
centres are relatively uncommon and the resulting spectra are
very sensitive to the magnitudes of the one and two bond JPP
coupling constants. The simulated spectra of 2–4 (using the shift
and coupling constant data in Tables 1–4) gave reasonable fits with
those experimentally observed and resulted in similar JPP values
Fig. 3 Insertion of chalcogens into the hexaphospha-pentaprismane,
t
P6C4 Bu4.
(Scheme 1). All the new compounds were fully characterised by
multi-nuclear NMR spectroscopy, elemental analyses, and single
crystal X-ray diffraction studies.
within the series of compounds. The 119Sn{ H} and 207Pb{ H}
1
1
NMR spectra of compounds 3 and 4 were also recorded directly.
Scheme 1
1
t
Fig. 4 Observed (lower part) and simulated (upper part) 31P{ H} NMR spectrum of Ge{N(SiMe3)2}2P6C4 Bu4 2.
2826 | Dalton Trans., 2008, 2825–2831
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Table 1 31P NMR data for compounds 2–4. Chemical shifts in ppm,
coupling constants in Hz (for 3, M = Sn; For 4, M = Pb)
dPC,C 1J(PAPB)
1J(PAM) 2J(PBM)
ꢀ
ꢀ
ꢀ
Compound dPA,A
dPB,B
2
3
4
26.5 134.5 206.4 320
−6.12 120.1 197.0 318
−19.3 127.1 188.9 343
—
1352
1737
—
—
86
1
t
The 31P{ H} NMR spectrum of Ge{N(SiMe3)2}2P6C4 Bu4
2
t
Fig. 5 Molecular structure of Ge{N(SiMe3)2}2P6C4 Bu4 2. Selected bond
shows the expected three sets of widely spaced multiplets (Fig. 4).
The PA resonance occurs as a large doublet of multiplets at
26.5 ppm as does the PB resonance centered at 134.5 ppm with
the same large coupling.
◦
˚
distances (A) and angles ( ): Ge–N(1) 1.876(4), Ge–N(2) 1.883(4), Ge–P(3)
2.3915(12), Ge–P(6) 2.4091(12); P(3)–Ge–P(6) 90.65(4), N(1)–Ge–N(2)
109.28(1), N(1)–Ge–P(3) 110.33(11), N(1)–Ge–P(6) 117.79(11), N(2)–
Ge–P(6) 111.06(11), N(2)–Ge–P(3) 110.33(10), Ge–P(3)–C(2) 101.53(14),
Ge–P(3)–P(2) 91.60(5), C(2)–P(3)–P(2) 99.60(15), Ge–P(6)–C(4)
100.31(14), Ge–P(6)–P(5) 92.69(5), P(5)–P(6)–C(4) 99.21(15).
The PC resonance exhibits a smaller multiplet at 206.4 ppm.
1
The 31P{ H} NMR spectrum of 2 was simulated (Fig. 4) and the
resulting JPP coupling constants are listed in Table 2.
˚
(2.308 A). Interestingly there is hardly any change in the geometry
of Ge{N(SiMe3)2}2 in forming the insertion product 2 even though
there is a formal oxidation state change of two for Ge. Thus, the
9
˚
mean Ge–N distance in Ge{N(SiMe3)2}2 is 1.876(5) A and in 2 is
˚
1.878(4) A, while the N–Ge–N bond angle in Ge{N(SiMe3)2}2 is
107.1(2)◦ and in 2 is 109.28(1)◦.
t
The analogous tin compound Sn{N(SiMe3)2}2P6C4 Bu4 3 shows
1
1
very similar 31P{ H}, 1H and 13C{ H} NMR spectroscopic features
to 2 (see Fig. 6). The PA resonance is a widely spaced doublet
of multiplets centered at −6.12 ppm as is the PB resonance
at 120.1 ppm both exhibiting the same large coupling. The PC
1
The H NMR spectrum showed the expected two singlets for
the different tBu environments at 1.21 and 1.49 ppm respectively,
but interestingly two resonances for the SiMe3 protons at 0.63 and
0.51 ppm. The latter behaviour presumably results from restricted
rotation of the bulky –N(SiMe3)2 groups around the N–Ge bonds
which results in an orientation in which one SiMe3 group is aligned
close to a P atom of one 5-membered ring while the other SiMe3
group lies adjacent to a C atom of the second ring, as subsequently
confirmed in the solid state structure (vide infra).
resonance gives a smaller multiplet at 197.0 ppm. The 119Sn{ H}
1
NMR spectrum shows a well-resolved triplet at 130.4 ppm
1
1
{ J(PASn) = 1352 Hz}. The simulated 31P{ H} NMR spectrum
of 3 is shown in Fig. 6 and JPP coupling constants are listed in
Table 3.
The 1H NMR spectrum of 3, like that of 2, showed the expected
two resonances for the two tBu environments and two resonances
for the two stereo-inequivalent SiMe3 groups.
The molecular structure of 2 was confirmed by a single crystal
X-ray diffraction study and is shown in Fig. 5. The germanium
centre lies in a distorted tetrahedral environment (P(3)–Ge–P(6)
angle = 90.65(4)◦), which is slightly smaller than that found in
The molecular structure of 3 was confirmed by a single crystal
X-ray diffraction study (Fig. 7). It is similar to that of the Ge
analogue and reveals that the Sn centre is in a distorted tetrahedral
˚
environment with a mean Sn–P bond length of (2.589 A) which
t
4
is comparable to the Sn–P bond distance in [tBu2Sn(PPh)3]
the cage compound P6C4 Bu4GeI2 made by treatment of GeI4
t
10
t
11
˚
˚
˚
with KP3C2 Bu2. The mean Ge–P bond length in 2 (2.4003 A)
(2.5435 A), and in ( Bu2SnPH)2 (2.546 A). The P(3)–Sn–P(6)
angle is 86.02(6)◦ and the N–Sn–N angle is 105.2(2)◦.
t
8
˚
is longer than that in P6C4 Bu4GeI2 (2.337 A) or in (H3Ge)3P
t
t
Table 2 JPP coupling constants (in Hz) for Ge{N(SiMe3)2}P6C4 Bu4 2
Table 3 JPP coupling constants (in Hz) for Sn{N(SiMe3)2}P6C4 Bu4 3
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
PC
PC
PB
PB
PA
PC
PC
PB
PB
PA
PA
PB
PC
0
13
5
10
−14
7
0
320
52
PA
PB
PC
−4
23
−2
5
−12
8
6
318
51
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1
t
Fig. 6 Experimental (upper part) and simulated (lower part) 31P{ H} NMR spectra of Sn{N(SiMe3}2P6C4 Bu4 3.
Table 4 JPP
(NMe2)2C6H3}2P6C4 Bu4 4
coupling
constants
(in
Hz)
for
Pb{2,6-
Interestingly, as in the case of the Ge system, there is no
t
significant change in the geometry of Sn{N(SiMe3)2}2 in forming
the insertion product 3. The mean Sn–N distance in crystalline
ꢀ
ꢀ
ꢀ
PC
PC
PB
PB
343
PA
12
˚
˚
Sn{N(SiMe3)2}2 is 2.09(1) A and in 3 is 2.080 A, while the N–Sn–
N bond angle in Sn{N(SiMe3)2}2 is 104.7(2)◦ and in 3 is 105.2(2)◦
PA
PB
PC
−13
11
−7
13
2
9
8
37
t
The lead compound Pb{C6H3(NMe2)2-2,6}2P6C4 Bu4
4
was made from
1 by treatment with the plumbylene
Pb{C6H3(NMe2)2}2 and is a rather rare example of a compound
containing a Pb(IV)–P bond. As can be seen in Fig. 8, its 31P{ H}
1
NMR spectrum is very similar to those discussed above for the
Ge and Sn analogues 2 and 3 exhibiting doublets of multiplets at
−19.3, 127.1 and 188.9 ppm for PA, PB and PC respectively. The
coupling 1J(PAPb) = 1737 Hz, and two bond coupling 2J(PBPb) =
86 Hz.
t
The molecular structure of Pb{2,6-(NMe2)2C6H3-2,6}2P6C4 Bu4
1
simulated 31P{ H} NMR spectrum of 4 is shown in Fig. 8 and JPP
4 was confirmed by a single crystal X-ray diffraction study (Fig. 9)
and is similar to that of the analogous Sn and Ge structures.
The Pb centre lies in a distorted tetrahedral environment with a
P(3)–Pb–P(6) angle of 84.55(4)◦ and a mean Pb–P bond length of
coupling constants are listed in Table 4.
1
The H NMR spectrum of 4 showed the expected two reso-
nances for the tBu groups and two resonances for the two stereo-
inequivalent NMe2 groups (as a result of restriction of the free
˚
˚
2.6295 A, which is comparable to the Pb–P bond distance (2.611 A)
1
rotation around the C–Pb bond). The 207Pb{ H} NMR spectrum
in P7[(PbMe3)3.13 The P–C and P–P distances in 2, 3 and 4 are very
close to their counterparts in P6C4 Bu4 1.
t
showed a triplet of triplets, which corresponds to one bond
2828 | Dalton Trans., 2008, 2825–2831
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t
Fig. 7 Molecular structure of Sn{N(SiMe3)2}2P6C4 Bu4 3. Selected
t
bond distances (A) and angles (◦): Sn–N(1) 2.077(6), Sn–N(2)
˚
Fig. 9 Molecular structure of Pb{C6H3(NMe2)2-2,6}2P6C4 Bu4 4. Se-
◦
˚
lected bond distances (A) and angles ( ): Pb–P(3) 2.626(1), Pb–P(6)
2.633(1), Pb–C(21) 2.224(5), Pb–C(31) 2.241(5); P(3)–Pb–P(6) 84.55(4),
C(21)–Pb–C(31) 104.48(18), C(21)–Pb–P(3) 115.97(13), C(21)–Pb–P(6)
111.28(12), C(31)–Pb–P(6) 119.96(14), C(31)–Pb–P(3) 120.23(14),
Pb–P(3)–C(2) 99.21(19), Pb–P(3)–P(2) 93.59(6), C(2)–P(3)–P(2) 99.13(16),
Pb–P(6)–C(4) 100.47(16), Pb–P(6)P(5) 92.23(6), P(5)–P(6)–C(4) 99.04(17).
2.083(6), Sn–P(3) 2.554(2), Sn–P(6) 2.624(2); P(3)–Sn–P(6) 86.02(6),
N(1)–Sn–N(2) 105.2(2), N(1)–Sn–P(3) 116.57(16), N(1)–Sn–P(6)
111.92(18), N(2)–Sn–P(6) 123.18(17), N(2)–Sn–P(3) 113.83(19),
Sn–P(3)–C(2) 100.5(2), Sn–P(3)–P(2) 91.07(9), C(2)–P(3)–P(2) 99.3(2),
Sn–P(6)–C(4) 98.8(2), Sn–P(6)P(5) 94.09(10), P(5)–P(6)–C(4) 97.9(3).
We have also carried out a single crystal X-ray analysis of
Pb{2,6-(NMe2)2C6H3}2 5 and its molecular structure is shown in
Fig. 10. It can be seen that the structural features in 5 are hardly
changed from those in the insertion product 4. Thus, the Pb–C
average distance in 4 is 2.232(5) A and in 5 is 2.327(5) A; likewise
the C–Pb–C bond angle in 4 is 104.48(18)◦ and in 5 is 102.19(17)◦.
This behaviour parallels that of compounds 2 and 3 discussed
earlier.
Several attempts were made to carry out analogous reac-
tions of P6C4 Bu4 1 with silylenes Si(NCHtBu)2(C6H4-1,2)14 or
t
Si(NtBuCH)2 under various reaction conditions, but unexpect-
15
˚
˚
edly no reaction was observed. Treatment of 1 with the carbene
C(NtBuCH)2 gave an unidentified product with a very compli-
16
1
cated 31P{ H} NMR spectrum indicating no simple insertion of
1
t
Fig. 8 Experimental (upper part) and simulated (lower part) 31P{ H} NMR spectra of Pb{C6H3(NMe2)2-2,6}2P6C4 Bu4 4.
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t
Synthesis of Ge{N(SiMe3)2}2P6C4 Bu4 2
t
A mixture of P6C4 Bu4 (0.06 g, 0.13 mmol) and Ge{N(SiMe3)2}2
(0.05 g, 0.13 mmol) was stirred in hexane (15 ml) for 48 h. The sol-
t
vent was then removed in vacuo to give Ge{N(SiMe3)2}2P6C4 Bu4,
which was crystallised from Et2O to afford colourless crystals
(mp 225 ◦C, 0.66 g, 60%). Found: C 45.17, H 8.37, N 3.32.
C32H72N2GeP6Si4 requires C 44.92, H 8.48, N 3.27%.
Spectroscopic data. (C6D6, 25 ◦C), 31P{ H} NMR (121.49
1
ꢀ
ꢀ
ꢀ
MHz): dPA,A = 26.5 (dm), dPB,B = 134.5 (dm), dPC,C = 206.4
(m). H NMR (300 MHz): dH(tBu) = 1.49 (s, 18H), dH(tBu) =
1
1.21 (s, 18H), dH(SiMe3) = 0.63 (s, 18H), dH(SiMe3) = 0.51 (s,
18H). 29Si{ H}NMR (99.36 MHz): dSiMe3 = 6.11 (s), dSiMe3 =
1
1
5.77 (s). 13C{ H} NMR (125.76 MHz): dC(SiMe3) = 8.77 and 8.69,
Fig. 10 Molecular structure of Pb{(NMe2)2C6H3-2,6}2 5. Selected bond
◦
˚
distances (A) and angles ( ): Pb(1)–C(1) 2.328(5), Pb(1)–C(7) 2.325(5);
C(1)–Pb–C(7) 102.19(17).
dC(CH3) = 31.84 and 27.53, dC(tBu) = 35.96 and 37.81 ppm. MS
(EI): m/z 856 (50%, [M]+), 841 (100%, [M − Me]+).
the carbene into the unique P–P bond of 1 had occurred as in the
Crystal data for 2. C32H72GeN2P6Si4, M = 855.69, triclinic,
case of germylenes, stannylenes or plumbylenes.
¯
space group P1 (No. 2), a = 18.0331(4), b = 18.1166(5), c =
◦
˚
˚
24.3208(7) A, a = 82.831(2), b = 69.414(2), c = 65.093(2) ; V =
Conclusions
6743.9(3) A , T = 173(2) K, Z = 6, Dc = 1.26 Mg m−3, l =
3
−1
˚
1.03 mm , k = 0.71073 A, F(000) = 2736, crystal size 0.20 ×
The specific insertion of the “heavy carbenes” MR2 (M = Ge, Sn or
0.20 × 0.05 mm, 46958 measured reflections, 23675 independent
reflections (Rint = 0.063), 16354 reflections with I > 2r(I), Final
indices R1 = 0.053, wR2 = 0.100 for I > 2r(I), R1 = 0.094, wR2 =
0.116 for all data. Data collection: KappaCCD. Program package
WinGX.17 Refinement using SHELXL-97.18
Pb) into the unique P–P bond between the two 5-membered rings
t
of the pentaphospha-prismane cage P6C4 Bu4. has been shown to
parallel the behaviour of the isoelectronic chalcogen systems S, Se
and Te suggesting that a common reaction mechanism obtains.
Experimental
t
Synthesis of Sn{N(SiMe3)2}2P6C4 Bu4 3
All manipulations of air-and/or moisture-sensitive compounds
were carried out under rigorously anhydrous and oxygen-free
conditions using standard high vacuum Schlenk line techniques or
in an inert atmosphere. Glassware and Schlenk tubes were flame
dried before used. Solvents were dried and distilled before use.
NMR solvents were purified by refluxing over a suitable drying
t
A mixture of P6C4 Bu4 (0.0 4 g, 0.09 mmol) and Sn{N(SiMe3)2}2
(0.04 g, 0.09 mmol) was stirred in hexane (15 ml) for 24 h. The sol-
t
vent was then removed in vacuo to give Sn{N(SiMe3)2}2P6C4 Bu4,
which was crystallised from hexane at −35 ◦C to afford yellow
crystals (mp 226 ◦C, 0.05 g, 60%). Found: C 42.10, H 7.51, N 2.97.
C32H72 N2P6Si4Sn requires C 42.62, H 8.05, N 3.11%.
agent, and vacuum-transferred into ampoules. 31P and H NMR
1
spectra were acquired on a Bruker Avance 300DPX spectrometer
operating at 300 MHz for 1H measurements, and 121.49 MHz for
31P measurements. 1H NMR spectra are referenced to the residual
proton chemical shift of the internal deuterated solvent (which in
turn is referenced to TMS). 31P NMR spectra are referenced to
H3PO4 (87% H3PO4 in D2O as an external standard). All spectra
were recorded at room temperature. Mass spectra (EI and FAB)
were recorded by Dr A. Abdul-Sada at the University of Sussex.
Single crystal X-ray diffraction studies were carried out using an
Enraf Nonius KAPPACCD diffractometer.
Spectroscopic data. (C6D6, 25 ◦C), 31P{ H} NMR (121.49
1
ꢀ
ꢀ
ꢀ
MHz): dPA,A = −6.12 (dm), dPB,B = 120.1 (dm), dPC,C = 197
1
(m). H NMR (300 MHz): dH(tBu) = 1.48 (s, 18H), dH(tBu) =
1.26 (s, 18H), dH(SiMe3) = 0.52 (s, 18H), dH(SiMe3) = 0.47 (s,
1
18H). 29Si{ H} NMR (99.36 MHz): dSiMe3 = 5.4 (s), dSiMe3 =
1
5.2 (s). 13C{ H} NMR (125.76 MHz): dC(SiMe3) = 7.55 and 7.46,
1
dC(CH3) = 27.5 and 31.5, dC(tBu) = 36.0 and 37.9. 119Sn{ H}
1
NMR (186.5 MHz): dSn = 130.4 (t) ppm. J(PASn) = 1352 Hz.
MS (EI), m/z: 902 (80%, [M]+).
Ge{N(SiMe3)2}2, Sn{N(SiMe3)2} and Pb{C6H3(NMe2)2-2,6}2
were synthesised by literature methods.6,7
Crystal data for 3. C32H72N2P6Si4Sn, M = 901.79, triclinic,
¯
space group P1 (No. 2), a = 11.9453(17), b = 13.7446(14), c =
t
Synthesis of P6C4 Bu4 1
◦
˚
˚
15.126(2) A, a = 114.191(7), b = 93.524(5), c = 94.335(9) ; V =
3
In an alternative synthesis to those already described in the
literature,1 a THF solution of I2 (0.47 g, 1.85 mmol in 10 ml
2247.2(5) A , T = 173(2) K, Z = 2, Dc = 1.33 Mg m−3, l =
−1
˚
0.91 mm , k = 0.71073 A, F(000) = 948, crystal size 0.40 ×
t
THF) was added to K(P3C2 Bu2) (1 g, 3.7 mmol in 15 ml THF)
0.05 × 0.02 mm, 13494 measured reflections, 6186 independent
reflections (Rint = 0.096), 4261 reflections with I > 2r(I), Final
indices R1 = 0.061, wR2 = 0.120 for I > 2r(I), R1 = 0.102,
wR2 = 0.136 for all data. Data collection: KappaCCD. Program
package WinGX. Refinement using SHELXL-97.
at −40 ◦C and the mixture warmed to room temperature. The
solution became orange and was stirred for a further 96 h. Solvent
was removed and the product extracted with hexane. Cooling to
−40 ◦C afforded orange crystals of 1 (300 mg, 20%).
2830 | Dalton Trans., 2008, 2825–2831
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t
Synthesis of Pb{C6H3(NMe2)2-2,6}2P6C4 Bu4 4
References
t
1 (a) K. B. Dillon, F. Mathey and J. F. Nixon, Phosphorus, The Carbon
Copy: From Organophosphorus to Phospha-organic Chemistry, Wiley,
New York, 1998; (b) Phosphorous-Carbon Heterocyclic Chemistry: The
Rise of a New Domain, ed. F. Mathey, Pergamon, Oxford, 2001; (c) F.
Mathey, Angew. Chem., Int. Ed., 2003, 42, 1578.
A solution of P6C4 Bu4 (0.07 g, 0.15 mmol) and Pb{C6H3(NMe2)2-
2,6}2 (0.08 g, 0.15 mmol) was stirred in hexane (20 ml)
for 48 h. The solvent was then removed in vacuo to give
t
Pb{C6H3(NMe2)2}2P6C4 Bu4 which was crystallised from Et2O to
give pale orange crystals (mp 140 ◦C decomp., 0.075 g, 50%).
Found: C 48.13, H 6.66. C40H66N4P6Pb requires C 48.24, H 6.68%.
2 (a) R. Streubel, Angew. Chem., Int. Ed. Engl., 1995, 34, 436 and
references therein; (b) A. Mack and M. Regitz, in Carbocyclic and Het-
erocyclic Cage Compounds and Their Building Blocks, ed. K. K. Laali,
J. A. I. Press, Stamford, CT, USA, 1999, p. 199; (c) J. F. Nixon,
in Carbocyclic and Heterocyclic Cage Compounds and Their Building
Blocks, ed. K. K. Laali, J. A. I. Press, Stamford, CT, USA, 1999, p.
257; (d) L. Weber, Adv. Organomet. Chem., 1997, 41, 1; (e) M. Regitz,
A. Hoffmann and U. Bergstra¨sser, in Modern Acetylene Chemistry,
ed. P. J. Stang and F. Diederich, VCH, Weinheim, 1995; (f) R. Appel,
in Multiple Bonds and Low Coordination in Phosphorus Chemistry, ed.
M. Regitz and O. Scherer, Georg Thieme Verlag, New York, 1990, p.
153; (g) R. Bartsch, P. B. Hitchcock and J. F. Nixon, J. Organomet.
Chem., 1989, 375, C31; (h) V. Caliman, P. B. Hitchcock, J. F. Nixon, M.
Hofmann and P. von R. Schleyer, Angew. Chem., Int. Ed. Engl., 1994,
33, 2202; (i) B. Geissler, T. Wettling, S. Barth, P. Binger and M. Regitz,
Synthesis, 1994, 1337; (j) F. Tabellion, A. Nachbauer, S. Leininger, C.
Peters, F. Preuss and M. Regitz, Angew. Chem., Int. Ed., 1998, 37,
1233; (k) T. Wettling, J. Schneider, O. Wagner, C. G. Kreiter and M.
Regitz, Angew. Chem., Int. Ed. Engl., 1989, 28, 1013; (l) B. Geissler,
S. Barth, U. Bergstra¨sser, M. Slany, J. Durkin, P. B. Hitchcock, M.
Hofmann, P. Binger, J. F. Nixon, P. von R. Schleyer and M. Regitz,
Angew. Chem., Int. Ed. Engl., 1995, 34, 484; (m) M. M. Al-Ktaifani,
Spectroscopic data. (C6D6, 25 ◦C), 31P{ H} NMR (121.49
1
ꢀ
ꢀ
ꢀ
MHz): dPA,A = −19.3 (dm), dPB,B = 127.1 (dm), dPC,C = 188.9
(m). 1H NMR (300 MHz): dH(tBu) = 1.42 (s, 18H), dH(tBu) = 1.24
(s, 18H), dH(NMe2) = 2.88 (s, 12H), dH(NMe2) = 2.20 (s, 12H),
dH(C6H3) = 6.9 (m, 6H). 13C{ H} (125.76 MHz): dC(CH3) = 28.20
1
and 30.50, dC(tBu) = 37.70 and 36.00, dC(NCH3) = 40.60 (m) and
46.41 (m). 207Pb{ H} NMR (104.68 MHz): dPb = 530.9 (tt) ppm
1
1J(PAPb) = 1737 Hz, 2J(PBPb) = 86 Hz. MS (EI), m/z: 996 (10%,
[M]+).
Crystal data for 4. C40H66N4P6Pb, M = 995.98, monoclinic,
space group P21/n (No. 14), a = 11.2177(3), b = 33.3392(11), c =
◦
3
˚
˚
13.1175(4) A, b = 112.074(2) , V = 4546.2(2) A , T = 173(2)
−3
−1
˚
K, Z = 4, Dc = 1.46 Mg m , l = 3.95 mm , k = 0.71073 A,
F(000) = 2024, crystal size 0.2 × 0.1 × 0.1 mm, 23962 measured
reflections, 10524 independent reflections (Rint = 0.070), 7750
reflections with I > 2r(I), Final indices R1 = 0.046, wR2 =
0.093 for I > 2r(I), R1 = 0.075, wR2 = 0.103 for all data. Data
collection: KappaCCD. Program package WinGX. Refinement
using SHELXL-97.
W. Bauer, U. Bergstra¨sser, B. Breit, M. D. Francis, F. W. Heinemann,
P. B. Hitchcock, A. Mack, J. F. Nixon, H. Pritzkow, M. Regitz, M.
Zeller and U. Zenneck, Chem.–Eur. J., 2002, 8, 2622; (n) A. G. Avent,
F. G. N. Cloke, M. D. Francis, P. B. Hitchcock and J. F. Nixon, Chem.
Commun., 2000, 879; (o) M. M. Al- Ktaifani, P. B. Hitchcock and J. F.
Nixon, Inorg. Chim. Acta, 2003, 356, 103.
3 S. J. Black, M. D. Francis and C. Jones, Chem. Commun., 1997, 305.
4 A. G. Avent, F. G. N. Cloke, M. D. Francis, P. B. Hitchcock and J. F.
Nixon, Chem. Commun., 2000, 879.
Crystal data for 56
5 M. M. Al-Ktaifani, D. P. Chapman, M. D. Francis, P. B. Hitchcock,
J. F. Nixon and L. Nyula´szi, Angew. Chem., Int. Ed., 2001, 40, 3474.
6 C. Drost, P. B. Hitchcock, M. F. Lappert and L. J- M. Pierssens, Chem.
Commun., 1997, 1141.
7 P. J. Davidson, D. H. Harris and M. F. Lappert, J. Chem. Soc., Dalton
Trans., 1976, 2268.
8 D. W. H. Rankin, A. G. Robiette, G. M. Sheldrick, B. Beagley and T. G.
Hewitt, J. Inorg. Nucl. Chem., 1969, 31, 2351.
9 R. W. Chorley, P. B. Hitchcock, M. F. Lappert, W.-P. Leung, P. P. Power
and M. M. Olmstead, Inorg. Chim. Acta, 1992, 200, 203.
10 T. L. Breen and D. W. Stephan, Organometallics, 1997, 16, 365.
11 D. Ha¨nssgen, H. Aldenhoven and M. Nieger, Chem. Ber., 1990, 123,
1837.
C23H33N4Pb, M = 572.72, monoclinic, space group P21/n (No. 14),
◦
˚
a = 13.714(4), b = 10.324(3), c = 17.259(5) A, b = 109.372(4) ,
V = 2305.1(11) A , T = 173(2) K, Z = 4, Dc = 1.65 Mg m−3, l =
3
˚
−1
˚
7.334 mm , k = 0.71073 A, F(000) = 1124, crystal size 0.3 × 0.2 ×
0.2 mm, 14598 measured reflections, 5471 independent reflections
(Rint = 0.0494), 4226 reflections with I > 2r(I), Final indices R1 =
0.0365, wR2 = 0.0837 for I > 2r(I), R1 = 0.0547, wR2 = 0.0962
for all data. Data collection: Bruker SMART. Program package
WinGX. Refinement using SHELXL-97.
Acknowledgements
12 T. Fjeldberg, H. Hope, M. F. Lappert, P. P. Power and A. J. Thorne,
J. Chem. Soc., Chem. Commun., 1983, 639.
13 D. Weber, C. Mujica and H. G. Schnering, Angew. Chem., Int. Ed. Engl.,
1982, 21, 863.
14 B. Gehrhus, M. F. Lappert, J. Heinicke, R. Boese and D. Bla¨ser, J. Chem.
Soc., Chem. Commun., 1995, 1931.
15 R. West and M. Denk, Pure Appl. Chem., 1996, 68, 785.
16 A. J. Arduengo, R. L. Harlow and M. Kline, J. Am. Chem. Soc., 1991,
113, 361.
17 L. J. Farrugia, WinGX, J. Appl. Crystallogr., 1999, 32, 837.
18 G. M. Sheldrick, SHELXL-97, University of Gottingen, Gottingen,
1997.
We acknowledge Dr Peter Loennecke for determining the crys-
tal and molecular structure of compound 5 and the late Dr
A. G. Avent for the simulation of the 31P NMR spectra. M. M. Al-
K. thanks the Syrian Atomic Energy Commission for a stu-
dentship and P.U. thanks the Euopean Commision for a TMR
grant. J.F.N. acknowledges continuing financial support from
the EPSRC for phospha-organometallic chemistry at Sussex
University.
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 2825–2831 | 2831
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