Facile transformations of a 1,3,5-triphosphacyclohexadienyl anion within the coordination sphere of group 13 and 14 elements: Synthesis of 1,3-diphosphacyclopentadienyl complexes and phosphaorganometallic cage compounds

Article abstract of DOI:10.1021/om0605581

The reactivity of the lithium triphosphacyclohexadienyl complex Li[1,3,5-MeP₃C₃Bu₃^t] toward a range of group 13 and 14 halide complexes has been investigated. The heterocycle reacts with MX (M = Ga, In, or Tl; X = Cl or I) to give the diphosphacyclopentadienyl (i.e., diphospholyl) complexes [M(η⁵-1, 3-P₂C₃Bu₃^t)] in good yield via phosphinidene, PMe, elimination reactions. One complex, M = Tl, has been structurally characterized and found to exist as a one-dimensional polymer in the solid state. Similarly, the reactions of Li[MeP₃C ₃Bu₃^t] with MCl₂ (M = Sn or Pb) have given the tetraphosphametallocenes [M(η⁵-1,3-P₂C ₃Bu₃^t)₂], which have been structurally characterized. These exhibit fluxional behavior in solution, which has been examined by variable-temperature NMR studies. The monomeric guanidinatotin chloride complexes [LSnCl] (L = Cy₂NC(NAr) ₂- or (cis-2,6-Me₂C₅H₈N)C(NAr) ₂^-, Cy = cyclohexyl, Ar = C₆H ₃Pr₂ⁱ-2,6) have been prepared, structurally characterized, and treated with Li[MeP₃C₃Bu ₃^t]. Again, this has yielded diphospholyl complexes [LSn(η¹-1,3-P₂C₃Bu₃ ^t)] via phosphinidene elimination processes. In contrast, the reactions of Ph₃ECl, E = Sn or Pb, do not proceed via phosphinidene elimination reactions, but instead by triphosphacyclohexadienyl rearrangement processes that eventually lead to complexes [Ph3M(η²-P,P-MeP ₃C₃Bu₃^t], containing five-coordinate metal centers that are P,P-chelated by an anionic bicyclic ligand. In the case of the tin complex, a reaction intermediate has been isolated and shown to contain the first structurally characterized example of a 1,2- diphosphabicyclo[1.1.0]butane fragment. A mechanism for the formation of this intermediate has been proposed.

Full text of DOI:10.1021/om0605581

Organometallics 2006, 25, 4799-4807
4799
Facile Transformations of a 1,3,5-Triphosphacyclohexadienyl Anion
within the Coordination Sphere of Group 13 and 14 Elements:
Synthesis of 1,3-Diphosphacyclopentadienyl Complexes and
Phosphaorganometallic Cage Compounds
Markus Brym, Matthew D. Francis, Guoxia Jin, Cameron Jones,* David P. Mills, and
Andreas Stasch
Center for Fundamental and Applied Main Group Chemistry, School of Chemistry, Main Building, Cardiff
UniVersity, Cardiff, CF10 3AT, U.K.
ReceiVed June 26, 2006
The reactivity of the lithium triphosphacyclohexadienyl complex Li[1,3,5-MeP3C3But3] toward a range
of group 13 and 14 halide complexes has been investigated. The heterocycle reacts with MX (M ) Ga,
In, or Tl; X ) Cl or I) to give the diphosphacyclopentadienyl (i.e., diphospholyl) complexes [M(η5-1,3-
P2C3But3)] in good yield via phosphinidene, PMe, elimination reactions. One complex, M ) Tl, has been
structurally characterized and found to exist as a one-dimensional polymer in the solid state. Similarly,
the reactions of Li[MeP3C3But3] with MCl2 (M ) Sn or Pb) have given the tetraphosphametallocenes
[M(η5-1,3-P2C3But3)2], which have been structurally characterized. These exhibit fluxional behavior in
solution, which has been examined by variable-temperature NMR studies. The monomeric guanidinato-
-
tin chloride complexes [LSnCl] (L ) Cy2NC(NAr)2- or (cis-2,6-Me2C5H8N)C(NAr)2 , Cy ) cyclohexyl,
Ar ) C6H3Pri2-2,6) have been prepared, structurally characterized, and treated with Li[MeP3C3But3].
Again, this has yielded diphospholyl complexes [LSn(η1-1,3-P2C3But3)] via phosphinidene elimination
processes. In contrast, the reactions of Ph3ECl, E ) Sn or Pb, do not proceed via phosphinidene elimination
reactions, but instead by triphosphacyclohexadienyl rearrangement processes that eventually lead to
complexes [Ph3M(η2-P,P-MeP3C3But3)], containing five-coordinate metal centers that are P,P-chelated
by an anionic bicyclic ligand. In the case of the tin complex, a reaction intermediate has been isolated
and shown to contain the first structurally characterized example of a 1,2-diphosphabicyclo[1.1.0]butane
fragment. A mechanism for the formation of this intermediate has been proposed.
formed in low yield (among other products), presumably via
[Fe(η5-1,3,5-MeP3C3But3)2], which eliminates 2 equiv of the
phosphinidene fragment, PMe, as evidenced by the presence
of the known cyclophosphanes, (PMe)n, in the reaction mixture.
It seemed to us that p-block complexes of [MeP3C3But3]- may
display a similar facility for phosphinidene elimination, and if
so, they could potentially be utilized as sources for the transfer
of the phosphinidene, PMe, to other metal or organic fragments.
This would be synthetically advantageous, as there are currently
few molecular sources of unhindered phosphinidene fragments
available to the synthetic chemist.5 Our efforts to prepare the
first group 13 and 14 complexes of [MeP3C3But3]- are reported
herein.
Introduction
The coordination chemistry of heterocyclic ligand systems
containing low-coordinate λ3-phosphorus centers is a diverse
field that has rapidly escalated in recent years. It has become
clear that the replacement of one or more carbon centers in
classical four-, five-, and six-membered unsaturated ring systems
leads to heterocycles that can display both similar and very
different coordination chemistry and reactivity compared to their
hydrocarbon counterparts.1
Our recent activity in this arena2 has dealt with the transition
metal coordination chemistry of the triphosphabenzene, 1,3,5-
P3C3But3, and the triphosphacyclohexadienyl complex, Li[1,3,5-
MeP3C3But3], 1, the latter of which is formed by treating the
former with MeLi.3 This work has led to the first examples of
transition metal complexes of [MeP3C3But3]-, but has also
highlighted the ability of this ligand to undergo metal-mediated
transformations. Most notably, in the reaction of 1 with FeCl2,
the known tetraphosphaferrocene [Fe(1,3-P2C3But3)2]4 was
Results and Discussion
Group 13 Element(I) Chemistry. It is now well known that
-
hindered anionic, aromatic ligands, e.g., C5Me5 (Cp*), can
stabilize organo-group 13 compounds with the metal in the +1
oxidation state, e.g., the oligomeric metal diyls, [(MCp*)n], M
) Al, n ) 4; M ) Ga, n ) 6; M ) Tl, n ) ∞. In their
monomeric state, these possess metal-based sp-hybridized singlet
* To whom correspondence should be addressed. E-mail: jonesca6@
cardiff.ac.uk.
(1) For example: (a) Dillon, K. B.; Mathey, F.; Nixon, J. F. In
Phosphorus: The Carbon Copy; Wiley: Chichester, 1998. (b) Phosphorus-
Carbon Heterocyclic Chemistry: The Rise of a New Domain; Mathey, F.,
Ed.; Pergamon: Amsterdam, 2001. (c) Mathey, F. Angew. Chem., Int. Ed.
2003, 42, 1578, and references therein.
(4) Bartsch, R.; Cloke, F. G. N.; Green, J. C.; Matos, R. M.; Nixon, J.
F.; Suffolk, R. J.; Suter, J. L.; Wilson, D. J. J. Chem. Soc., Dalton Trans.
2001, 1013.
(2) Francis, M. D.; Holtel, C.; Jones, C.; Rose, R. P. Organometallics
2005, 24, 4216.
(3) Steinbach, J.; Renner, J.; Binger, P.; Regitz, M. Synthesis 2003, 1526.
(5) For example: (a) Lammertsma, K. Top. Curr. Chem. 2003, 229, 95,
(b) Mathey, F.; Tran Huy, N. H.; Marinetti, A. HelV. Chim. Acta 2001, 84,
2938, and references therein.
10.1021/om0605581 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 08/31/2006

4800 Organometallics, Vol. 25, No. 20, 2006
Brym et al.
Scheme 1
lone pairs, and accordingly, they are proving very useful as novel
Lewis bases in the formation of p-,6 d-,7 and even f-block8
complexes. It occurred to us that the π-system of bulky
[MeP3C3But3]- may similarly stabilize novel metal diyl com-
plexes of the type [:M(η5-MeP3C3But3)]. To this end, the lithium
salt 1 was reacted with metal(I) halides, which in all cases led
to the diphospholylmetal complexes 2-4 (Scheme 1) in good
yields after workup. It is apparent that the mechanisms of
formation of these complexes involve the initial formation of
the target complexes [M(η5-MeP3C3But3)], which undergo ring
contraction reactions via the elimination of the phosphinidene
fragment, PMe. Indeed, the known cyclophosphanes, (PMe)n,
are formed in the reactions, as evidenced by the presence of
multiplet signals centered at ca. δ 10 ppm in the 31P NMR
spectrum of the product mixtures.9 These phosphinidene elimi-
nation reactions are much cleaner than that observed in the
formation of [Fe(1,3-P2C3But3)2], as 2-4 were the only observed
phosphorus-containing products (other than (PMe)n). The pro-
posed ring contraction reactions must be facile, as following
each by 31P{1H} NMR spectroscopy showed they were complete
within 3 h and did not reveal any intermediates. It is worthy of
note that the lithium salt 1 also eliminates PMe to give the
diphosphacyclopentadienyl complex Li[1,3-P2C3But3], but only
on heating in THF at reflux for 3 h.10 Therefore, it seems that
coordination of [MeP3C3But3]- to the group 13 metal signifi-
cantly lowers the energy barrier to this elimination process.
Considering the facility of phosphinidene elimination in the
formation of 2-4, the reactions that gave these complexes were
carried out in the presence of the alkyne PhCtCPh in attempts
to trap the generated phosphinidene by forming the known
Figure 1. Thermal ellipsoid plot (25% probability surface) of a
fragment of one of the crystallographically independent polymeric
chains of [Tl(P2C3But3)] (4); hydrogen atoms are omitted for clarity.
P(1)-C(1) 1.758(16), C(1)-P(2) 1.762(17), P(2)-C(3) 1.833(16),
C(3)-C(2) 1.46(2), C(2)-P(1) 1.800(16), Tl(1)-centroid 2.815-
(5), Tl(1)′′-centroid 2.894(5), centroid-Tl(1)-centroid 162.60-
(9), Tl(1)-centroid-Tl(1)′′ 177.21(10). Symmetry transformation
used to generate equivalent atoms ′: x, 1-y, 1/2+z; ′′: x, 1-y,
z-1/2.
and 4 are their 31P{1H} NMR spectra, which exhibit singlet (δ
1
189.2 ppm) and doublet (δ 190.8 ppm, JPTl ) 159 Hz)
resonances, respectively. In addition, the mass spectra of both
compounds display molecular ion peaks.
Crystals of 2 suitable for X-ray crystallographic studies could
not be obtained, but good quality crystals of 4 were acquired
by sublimation. Its structure is depicted in Figure 1 and shows
it to exist as infinite one-dimensional polymer strands (NB: only
one of the two crystallographically independent strands is
shown), as do TlCp*14 and [Tl(1,2,4-P3C2But2)].15 In contrast,
the analogous indium complex, [In(η5-P2C3But3)], exists as
monomeric units in the solid state.13 The mean thallium-ring
centroid distance of 2.84 Å is similar to those in related
compounds [e.g., TlCp* 2.91 and 2.99 Å,14 [Tl(1,2,4-P3C2But2)]
2.85 and 3.22 Å15]. Moreover, the centroid-Tl-centroid angles
(166.9° mean) are close to those in the analogous triphospholyl
complex, [Tl(1,2,4-P3C2But2)] (171°), but significantly more
obtuse than the angles for TlCp* (145.5° mean). This difference
presumably results from the greater steric bulk of the ring in 4.
As is the case for [Tl(1,2,4-P3C2But2)] and [In(1,3-P2C3But3)],
the intra-ring P-C and C-C bonds in 4 are suggestive of
significant delocalization.
Group 14 Element(II) Chemistry. In light of the reactivity
that 1 displayed toward low oxidation state group 13 halides,
its reactions with a variety of group 14 element(II) halide
complexes were carried out with similar results. Treatment of
MCl2 (M ) Sn or Pb) with 1 afforded the tetraphosphametal-
locenes 5 and 6 in low isolated yields (Scheme 2). As with
2-4, the mechanism of formation of these complexes most
likely involves the initial formation of triphosphacyclohexadi-
enyl complexes, which facilely eliminate phosphinidene (PMe)
fragments. Resonances for the proposed intermediates could not
be observed when the reactions were followed by 31P NMR
spectroscopy, thus suggesting they are short-lived. The spectra
did, however, indicate that the formations of 5 and 6 were high
yielding. The low isolated yields of these compounds are
11
phosphirene MeP{C(Ph)}2 in [2+1] cycloaddition reactions.
These attempts were unsuccessful, as the reactions only afforded
2-4 and (PMe)n, without the involvement of the alkyne. Also
unsuccessful were reactions of 1 with a variety of metal(III)
compounds, MCl3 and Cy2MCl (M ) Al, Ga, or In; Cy )
cyclohexyl), all of which afforded the known triphosphacyclo-
hexa-1,4-diene MeP3C3But3(H),12 presumably via solvent proton
abstraction processes.
The spectroscopic data for 2 and 4 are consistent with their
formulations. Compound 3 has been previously reported to be
formed in the reaction of K[1,3-P2C3But3] with InI,13 and its
spectroscopic data are identical to those in that report (e.g., 31P-
{1H} NMR: δ 182 ppm). Most informative of the data for 2
(6) Cowley, A. H. Chem. Commun. 2004, 2369.
(7) Gemel, G.; Steinke, T.; Cokoja, M.; Kempter, A.; Fischer, R. A. Eur.
J. Inorg. Chem. 2004, 4161.
(8) Gamer, M. T., Roesky, P. W.; Konchenko, S. N.; Nava, P.; Ahlrichs,
R. Angew. Chem., Int. Ed. 2006, 45, 4447.
(9) Berger, S.; Braun, S.; Kalinowski, H.-O. 31P NMR-Spectroskopie;
Thieme: Stuttgart, 1991; Vol. 3, p 140.
(10) Steinbach, J.; Binger, P.; Regitz, M. Synthesis 2003, 2720.
(11) Lochschmidt, S.; Mathey, F.; Schmidpeter, A. Tetrahedron Lett.
1986, 27, 2635.
(12) Renner, J.; Bergstra¨sser, U.; Binger, P.; Regitz, M. Angew. Chem.,
Int. Ed. 2003, 42, 1863.
(13) Clentsmith, G. K. B.; Cloke, F. G. N.; Francis, M. D.; Green, J. C.;
Hitchcock, P. B.; Nixon, J. F.; Suter, J. L.; Vickers, D. M. J. Chem. Soc.,
Dalton Trans. 2000, 1715. NB: the authors have become aware that in
unpublished work, [Ga(P2C3But3)] can be prepared via a similar salt
elimination reaction, Nixon, J. F. Personal communication.
(14) Werner, H.; Otto, H.; Kraus, H. J. J. Organomet. Chem. 1986, 315,
57.
(15) Francis, M. D.; Hitchcock, P. B.; Nixon, J. F.; Schno¨ckel, H. J.;
Steiner, J. J. Organomet. Chem. 2002, 646, 191.

Synthesis of 1,3-Diphosphacyclopentadienyl Complexes
Organometallics, Vol. 25, No. 20, 2006 4801
Scheme 2
Figure 2. Variable-temperature 31P{1H} NMR spectra for [Pb-
(P2C3But3)2] (6).
probably due to their high solubility in organic solvents. In
contrast, the 2:1 reaction of 1 with GeCl2(dioxane) led to an
intractable mixture of many phosphorus-containing products.
As has been reported for other tetraphosphametallocenes, e.g.,
[Fe(1,3-P2C3But3)2],4 compounds 5 and 6 display fluxional
behavior in solution resulting from the rotation of the two
heterocycles with respect to each other. The difference here is
that the group 14 metallocenes are most likely bent, as has been
proposed for their hexaphospha-analogues, [M(1,2,4-P3C2But2)2]
(M ) Sn16 or Pb),17 though the latter have not been crystallo-
graphically characterized. At ambient temperature both tetra-
phosphametallocenes display singlet resonances (5 δ 196.9 ppm;
6 δ 202.6 ppm) in their 31P{1H} NMR spectra, with that of 6
1
exhibiting a JPPb coupling of 215 Hz. Variable-temperature
NMR studies were carried out on both complexes, and these
showed that upon cooling to -95 °C both spectra resolved into
two broad signals (spectra for 6 are shown in Figure 2). The
low-temperature spectrum of 5 was sufficiently resolved to allow
Figure 3. Thermal ellipsoid plot (25% probability surface) of the
molecular structure of [Pb(P2C3But3)2] (6); hydrogen atoms are
omitted for clarity. Selected bond lengths (Å) and angles (deg):
P(1)-C(1) 1.737(5), P(1)-C(3) 1.789(5), P(2)-C(1) 1.743(5),
P(2)-C(2) 1.812(5), P(3)-C(16) 1.740(5), P(3)-C(17) 1.814(5),
P(4)-C(16) 1.738(5), P(4)-C(18) 1.792(6), C(2)-C(3) 1.414(7),
C(17)-C(18) 1.412(7), centroid-Pb(1)-centroid 170.4(3). Selected
bond lengths (Å) and angles (deg) for [Sn(P2C3But3)2] (5): P(1)-
C(1) 1.735(3), P(1)-C(3) 1.797(3), P(2)-C(1) 1.745(3), P(2)-C(2)
1.809(3), P(3)-C(16) 1.733(3), P(3)-C(17) 1.805(3), P(4)-C(16)
1.740(3), P(4)-C(18) 1.799(3), C(2)-C(3) 1.394(4), C(17)-C(18)
1.407(4), centroid-Sn(1)-centroid 171.3(4).
2
an intra-ring JPP coupling of 34 Hz to be determined, though
1
the magnitude of the JSnP coupling could not be accurately
assigned. The resolution of the spectra for 5 and 6 can be
explained by a slowing of their ring rotations at low temperature
to a point where a near eclipsed conformation of the heterocycles
is favored, as is seen in the solid state (vide infra). This leads
to two chemically inequivalent sets of phosphorus nuclei, PA
and PB (Figure 2). An analysis of the spectra using the Eyring
equation gave values for the free energy of activation (∆Gq)
for the ring rotations of 34.73 kJ mol-1 (5) and 31.96 kJ mol-1
(6). The higher value for 5 is likely due to the smaller covalent
radius of Sn, relative to Pb, which would restrict ring rotation
in that compound. These values can also be compared to the
significantly larger barrier to rotation of 59.55 kJ mol-1 for [Fe-
(1,3-P2C3But3)2],4 which results from the smaller covalent radius
of Fe relative to the group 14 elements and the fact that the
rings in the heteroferrocene are most likely close to parallel.
The X-ray crystal structures of 5 and 6 are isomorphous, and
so only that for 6 is depicted in Figure 3, though relevant
geometrical parameters for 5 are included in the caption. In both,
the heterocycles have approximately η5-interactions with the
metals. They are near eclipsed, and their intra-ring P-C and
C-C distances are suggestive of bond delocalization. The
metallocenes are bent with centroid-M distances and centroid-
M-centroid angles of 2.50 Å (mean) and 171.3(4)° for 5 and
2.56 Å (mean) and 170.4(3)° for 6. The angles are markedly
more obtuse than in, for example, MCp*2 (M ) Sn (144.1°
mean),18 Pb (151.0°))19 and the closely related triphosphaplum-
bocene, [Pb(1,2,4-P3C2But2)(Cp*)] (142.2°),17 most likely be-
cause of the considerable steric bulk of the diphospholyl ligands
in 5 and 6.
To further explore the ability of 1 to undergo metal-mediated
phosphinidene elimination reactions, its reaction with com-
pounds of the type RMCl (R ) bulky alkyl or aryl, M ) Ge,
Sn, or Pb) were carried out. In all cases, intractable mixtures of
products were obtained. We have had recent success in utilizing
(16) Elvers, A.; Heinmann, F. W.; Wrackmeyer, B.; Zenneck, U. Chem.
Eur. J. 1999, 5, 3143.
(17) Durkin, J. J.; Francis, M. D.; Hitchcock, P. B.; Jones, C.; Nixon, J.
J. Chem. Soc., Dalton Trans. 1999, 4057.
(18) Jutzi, P.; Kohl, F.; Hofmann, P.; Kru¨ger, C.; Tsay, Y. H. Chem.
Ber. 1980, 113, 757.
(19) Atwood. J. L.; Hunter, W. E.; Cowley, A. H.; Jones, R. A.; Stewart,
C. A. J. Chem. Soc., Chem. Commun. 1981, 925.

4802 Organometallics, Vol. 25, No. 20, 2006
Brym et al.
very bulky guanidinate ligands to stabilize monomeric, low
oxidation state main group complexes.20 Accordingly, a range
of guanidinato-element halide complexes, [LECl] (L )
-
Cy2NC(NAr)2 or (cis-2,6-Me2C5H8N)C(NAr)2-, Ar ) C6H3-
Pri2-2,6; E ) Ge or Sn), were prepared for reaction with 1. Those
reactions with the germanium complexes led to mixtures of
unidentified products. The reactions with monomeric [LSnCl]
were, however, more successful, and therefore full synthetic,
spectroscopic, and structural details for the precursor complexes
are included in the Supporting Information. Similar to the
formation of 5, treatment of [LSnCl] with 1 led to phosphinidene
elimination and the formation of the tin-diphospholyl com-
plexes 7 and 8 in low to moderate isolated yields (Scheme 2),
though the 31P NMR spectra of the total reaction mixtures
suggested these were the major products.
The solution state spectroscopic data for 7 and 8 are
suggestive of symmetrical structures for these compounds, in
which the diphospholyl ring is η5-coordinated to the tin centers.
In particular, their 31P{1H} NMR spectra display single reso-
nances (7: δ 192.3 ppm; 8: δ 190.1 ppm) close to where that
of 5 was observed. In contrast to 5, however, cooling solutions
of 7 and 8 to -90 °C led only to a broadening of the singlet
resonances and no further resolution. This is perhaps surprising,
as their solid state structures reveal a less symmetrical coordina-
tion of their diphospholyl rings to the tin centers. As both
compounds are effectively isostructural, only the molecular
structure for 7 is depicted in Figure 4, though relevant
geometrical parameters for 8 are included in the figure caption.
In each complex, the LSn fragment is within bonding distance
of only one P-center in what can be best described as an Sn-
heterocycle π-interaction lying somewhere between η1-P and
η3-CPC ligation (∑angles at P(1): 7, 256.4°; 8, 256.7°). An
examination of the intra-ring C-P and C-C distances suggests
only partial delocalization, and so the former mode could
predominate. A similar suggestion of the bonding in the
diphosphastannocene [Sn{η1-PC4-2,5-Ph2-3,4-(SiMe3)2}2] (Sn-P
2.76 Å mean) has been previously described.21 The geometries
of the four-membered heterocycles in 7 and 8 are close to those
in the tin halide precursors and indicative of delocalization over
the guanidinate ligand. Given the solid state structures of 7 and
8, the solution state NMR spectra of these complexes can be
best explained by fluxional migrations of the LSn fragments
between the two P-centers of the diphospholyl ligand. It is of
note that a similar sigmatropic fluxional migration of the
σ-bound Ph3Sn fragment about the same diphospholyl ring in
[Ph3SnIV(η1-P2C3But3)] (∑angles about the Sn-coordinated P
center: 294.4°) has been described by Cloke et al.22 In 7 and
8, it is unlikely that the fluxional migrations of the Sn(II)
fragments are sigmatropic, and, instead, they could proceed via
intermediate η5-Sn-diphospholyl interactions, especially con-
sidering that no 117,119Sn satellites were discernible for the
resonance in the 31P{1H} NMR spectra of each complex (cf.
5). Whatever the case, these dynamic processes must have low
energy barriers and be rapid on the NMR time scale even at
-90 °C.
Figure 4. Thermal ellipsoid plot (25% probability surface) of the
molecular structure of [{Cy2NC(NAr)2}Sn(P2C3But3)] (7); hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and angles
(deg): Sn(1)-N(2) 2.210(4), Sn(1)-N(1) 2.319(4), Sn(1)-P(1)
2.7595(17), P(1)-C(1) 1.770(5), P(1)-C(3) 1.815(5), P(2)-C(1)
1.706(5), P(2)-C(2) 1.788(5), C(2)-C(3) 1.402(7), N(1)-C(16)
1.361(6), N(2)-C(16) 1.366(6), N(3)-C(16) 1.367(6), N(2)-Sn-
(1)-N(1) 58.38(13), N(2)-Sn(1)-P(1) 117.92(11), N(1)-Sn(1)-
P(1) 111.43(10), C(1)-P(1)-C(3) 96.6(2), C(1)-P(1)-Sn(1) 81.17-
(17), C(3)-P(1)-Sn(1) 78.66(16), C(16)-N(1)-Sn(1) 92.8(3),
C(16)-N(2)-Sn(1) 97.6(3), N(1)-C(16)-N(2) 108.3(4). Selected
bond lengths (Å) and angles (deg) for [{(cis-2,6-Me2C5H8N)C-
(NAr)2}Sn(P2C3But3)] (8): Sn(1)-N(2) 2.212(3), Sn(1)-N(1)
2.357(3), Sn(1)-P(1) 2.7754(12), P(1)-C(1) 1.766(4), P(1)-C(3)
1.829(4), C(1)-P(2) 1.719(4), P(2)-C(2) 1.795(4), C(2)-C(3)
1.405(6), N(1)-C(16) 1.344(5), N(2)-C(16) 1.354(4), N(3)-C(16)
1.372(4), N(2)-Sn(1)-N(1) 57.93(10), N(2)-Sn(1)-P(1) 118.08-
(8), N(1)-Sn(1)-P(1) 115.16(8), C(1)-P(1)-C(3) 96.98(19),
C(1)-P(1)-Sn(1) 80.30(14), C(3)-P(1)-Sn(1) 79.42(13), C(16)-
N(1)-Sn(1) 90.7(2), C(16)-N(2)-Sn(1) 96.9(2), N(1)-C(16)-
N(2) 110.5(3).
group 14 element(IV) compounds for the purpose of comparison.
Cloke et al. have found that the reaction of K[1,3-P2C3But3]
with Ph3SnCl leads cleanly to [Ph3Sn(η1-P2C3But3)], which
displays unusual fluxional behavior in solution, as described
above.22 Therefore, it seemed worthwhile to react 1 with
compounds of the type R3ECl (E ) group 14 element) to see if
similar compounds could be formed. The 1:1 reactions with Me3-
ECl or Ph3ECl (E ) Si or Ge) were, however, sluggish, and
after 24 h only a mixture of unreacted 1 and several unidentified
phosphorus-containing products could be observed in the 31P
NMR spectra of the reaction solutions. No pure products could
be obtained after subsequent workup. In contrast, treating 1 with
1 equiv of Ph3SnCl in hexane led cleanly, after 2 h, to a high
yield of the unusual colorless cage complex 9, which can be
considered as a 1,2-diphosphabicyclo[1.1.0]butane bridged in
its endo-positions by a P-C fragment (Scheme 3). Subsequently,
it was found that when solutions of 9 were left standing at
ambient temperature overnight, they took on an orange colora-
tion. This was found to be due to an isomerization of the
compound to the novel polycyclic system 10, which can be
drawn as two resonance forms, each containing an ylidic
P-center, a phosphaalkene fragment, and a phosphide center.
This isomerization was complete after 56 h. It is noteworthy
that there was no evidence for the formation of [Ph3Sn(P2C3-
But3)] in the reaction that gave 9 and 10. The corresponding
reaction of 1 with Ph3PbCl was not as clean but did afford a
Group 14 Element(IV) Chemistry. As the reactions of group
14 element(II) precursors generally led to the facile formation
of diphospholyl complexes via phosphinidene elimination
reactions, it was decided to investigate the reactivity of 1 toward
(20) Jones, C.; Junk, P. C.; Platts, J. A.; Stasch, A. J. Am. Chem. Soc.
2006, 128, 2206.
(21) Westerhausen, M.; Digeser, M. H.; No¨th, H.; Ponikwar, W.; Seifert,
T.; Polborn, K. Inorg. Chem. 1999, 38, 3207.
(22) Cloke, F. G. N.; Hitchcock, P. B.; Nixon, J. F.; Wilson, D. J.;
Nyulaszi, L.; Karparti, T. J. Organomet. Chem. 2005, 690, 3983.

Synthesis of 1,3-Diphosphacyclopentadienyl Complexes
Organometallics, Vol. 25, No. 20, 2006 4803
Scheme 3
low yield of the lead analogue of 10, viz., 11, among other
unidentified products after a reaction time of 4 h at 25 °C.
Interestingly, when this reaction was followed by 31P NMR
spectroscopy, no signals for an intermediate analogous to 9 were
observed. It seems feasible that it is formed but is much more
short-lived than its tin counterpart.
-268.3 ppm for 1,3-P2C2But2GeI2.27 The resonance for the
P-center that forms part of only one three-membered ring is at
much lower field (δ -8.4 ppm) than is normally seen for
phosphiranes and 2,4-diphosphabicyclo[1.1.0]butanes with exo-P
substituents.25b It is now clear that if the P substituents are in
endo-positions in such bicycles (as is the case for 9), such low-
field signals are the norm.25a,28 In concert with the resonance
structures proposed for 10 and 11, the 31P{1H} NMR spectra
of each display AX2 patterns (e.g., 10: δ PA ) 35.3 ppm; δ PX
It is likely that 9 is formed via an initial stannylation of the
methylated P-center of [MeP3C3But3]- to give 12. In line with
this suggestion are theoretical studies on 1,3,5-triphosphacy-
clohexadienyl anions, which show their negative charge to reside
largely on this phosphorus.3 Indeed, treating triphosphacyclo-
hexadienyl anions with alkyl halides leads to stable 1-λ5,3-λ3,5-
λ3-triphosphinines analogous to 12.3 A 1,2-stannyl migration
could then occur to give 13, which contains a 1,3-diphosphab-
utadiene fragment. Compound 13 could then isomerize to give
9. This proposal seems reasonable, as 1,2-phosphorus to carbon
stannyl migrations can be low-energy processes for stannylated
unsaturated phosphorus heterocycles, e.g., [Ph3Sn(P2C3But3)].22
In addition, protonated triphosphacyclohexadienyl anions, cf.
12, can undergo 1,2-H migrations to give heterocycles related
to 13.23 With regard to the isomerization that gave 9, the only
other reported 1,2-diphosphabicyclo[1.1.0]butane, P2C2(SiMe3)4,24
is similarly formed via a facile isomerization of the correspond-
ing 1,3-diphosphabutadiene. It is not known what the mechanism
of isomerization of the, presumably, strained 9 to 10 entails,
but valence isomerizations of phospha- and diphosphabicyclo-
[1.1.0]butanes are now well known to give a variety of
unsaturated cyclic and acyclic systems,25 cf. hydrocarbon
bicyclo[1.1.0]butanes.26
117
119
) 87.1 ppm, 1JP
) 732 Hz, 1JP
) 767 Hz). The
Sn
Sn
119Sn{1H} NMR spectrum of 10 also exhibits a triplet resonance
at δ -85.5 ppm (1JPSn ) 767 Hz), cf. [Ph3Sn(P2C3But3)] δ
-146.2 ppm.
The molecular structures of 9 and 10 are depicted in Figures
5 and 6, respectively. The crystal structure of 11 is isomorphous
with that of 10, and therefore relevant geometrical parameters
for that compound can be found in the caption for Figure 6. To
the best of our knowledge, 9 contains the first structurally
characterized 1,2-diphosphabicyclo[1.1.0]butane fragment. Al-
though this appears strained, its intra-cyclic P-P and P-C
distances are all in the normal range.29 There is a fold angle of
109.1° between the two three-membered rings, which, not
surprisingly, is more acute than normally seen for nonbridged
endo,endo-2,4-diphosphabicyclo[1.1.0]butanes, e.g., 131.6° for
Cy2P2C2But2.28 Considering that only one set of signals was
observed in the 31P NMR spectrum of the reaction mixture that
afforded 9, this compound must be formed as only one isomer,
which its solid state structure shows to have the SnPh3 fragment
trans to the phosphorus-bound methyl group of the bridging
P-C fragment. The unusual structures of 10 and 11 show them
to have distorted square-based pyramidal metal centers that are
chelated by two phosphorus centers of an anionic triphosphabi-
cyclic ligand. Although complexes containing five-coordinate
MPh3 (M ) Sn or Pb) fragments are well known, there have
been no previously structurally characterized examples in which
the metal incorporates two P-donors.29 As a result, the M-P
distances in 10 and 11 are much longer than the means for all
structurally authenticated examples of such interactions (Sn-P
2.62 Å, Pb-P 2.78 Å),29 though still within the known ranges.
In addition, the P-M interactions in each compound are
The spectroscopic data for 9-11 are compatible with their
proposed structures. Of most note are their 31P{1H} NMR
spectra, which in the case of 9 exhibits three resonances. That
for the P-center that forms part of the two three-membered rings
is at high field (δ -284.7 ppm, 1JPP ) 184.5 Hz), in the normal
region for 1,3-diphosphabicyclo[1.1.0]butane systems, e.g., δ
(23) (a) Renner, J.; Bergsta¨sser, U.; Binger, P.; Regitz, M. Angew. Chem.,
Int. Ed. 2003, 42, 1863. (b) Heydt, H. Top. Curr. Chem. 2003, 223, 216.
(24) Niecke, E.; Metternich, H. J.; Streubel, R. Chem. Ber. 1990, 123,
67.
(25) (a) Slootweg, J. C.; Krill, S.; de Kanter, F. J. J.; Schakel, M.; Ehlers,
A. W.; Lutz, M.; Spek, A. L.; Lammertsma, K. Angew. Chem., Int. Ed.
2005, 44, 6579. (b) Niecke, E.; Fuchs, A.; Nieger, M. Angew. Chem., Int.
Ed. 1999, 38, 3028.
(27) Francis, M. D.; Hitchcock, P. B. Organometallics 2003, 23, 2891.
(28) Jones, C.; Platts, J. A.; Richards, A. F. Chem. Commun. 2001, 663.
(29) As determined by a survey of the Cambridge Crystallographic
Database, June 2006.
(26) The Chemistry of the Cyclopropyl Group, Part 2; Rappoprot, Z.,
Ed.; Wiley: Chichester, 1987; Chapter 19.

4804 Organometallics, Vol. 25, No. 20, 2006
Brym et al.
Figure 5. Thermal ellipsoid plot (25% probability surface) of the
molecular structure of [Ph3Sn(η1-C-MeP3C3But3)] (9); hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and angles
(deg): Sn(1)-C(1) 2.2371(17), P(1)-C(4) 1.8571(19), P(1)-C(1)
1.8766(18), P(1)-C(3) 1.8965(18), P(2)-C(2) 1.8595(18), P(2)-
C(1) 1.8675(18), P(2)-P(3) 2.1547(10), P(3)-C(2) 1.8705(18),
P(3)-C(3) 1.9172(18), C(4)-P(1)-C(1) 107.35(9), C(4)-P(1)-
C(3) 99.40(8), C(1)-P(1)-C(3) 96.14(8), C(2)-P(2)-C(1) 103.33-
(8), C(2)-P(2)-P(3) 54.95(6), C(1)-P(2)-P(3) 101.58(6), C(2)-
P(3)-C(3) 47.64(7), C(2)-P(3)-P(2) 54.47(6), C(3)-P(3)-P(2)
80.89(6), P(2)-C(1)-P(1) 106.75(9), P(2)-C(1)-Sn(1) 105.97-
(8), P(1)-C(1)-Sn(1) 100.51(8).
Figure 6. Thermal ellipsoid plot (25% probability surface) of the
molecular structure of [Ph3Sn(η2-P,P-MeP3C3But3)] (10); hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and angles
(deg): Sn(1)-P(1) 2.7558(16), Sn(1)-P(2) 2.9265(19), P(1)-C(2)
1.717(7), P(1)-C(1) 1.899(6), P(2)-C(3) 1.728(7), P(2)-C(1)
1.880(6), P(3)-C(3) 1.749(7), P(3)-C(2) 1.773(7), P(3)-C(4)
1.813(6), P(3)-C(1) 1.823(6), P(1)-Sn(1)-P(2) 64.08(4), C(2)-
P(1)-C(1) 86.9(3), C(3)-P(2)-C(1) 86.6(3), C(3)-P(3)-C(2)
120.4(3), C(3)-P(3)-C(1) 87.8(3), C(2)-P(3)-C(1) 87.7(3),
P(3)-C(1)-P(2) 88.4(2), P(3)-C(1)-P(1) 88.5(3), P(2)-C(1)-
P(1) 106.0(3), P(1)-C(2)-P(3) 96.2(3), P(2)-C(3)-P(3) 95.9(3).
Selected bond lengths (Å) and angles (deg) for [Ph3Pb(η2-P,P-
MeP3C3But3)] (11): Pb(1)-P(1) 2.887(3), Pb(1)-P(2) 2.965(3),
P(1)-C(2) 1.687(11), P(1)-C(1) 1.881(11), P(2)-C(3) 1.715(13),
P(2)-C(1) 1.929(12), P(3)-C(2) 1.740(11), P(3)-C(3) 1.749(12),
P(3)-C(4) 1.818(11), P(3)-C(1) 1.834(11), P(1)-Pb(1)-P(2)
63.27(7), C(2)-P(1)-C(1) 86.8(5), C(3)-P(2)-C(1) 86.3(5),
C(2)-P(3)-C(3) 120.6(6), C(2)-P(3)-C(1) 86.7(5), C(3)-P(3)-
C(1) 88.4(5), P(3)-C(1)-P(1) 88.0(5), P(3)-C(1)-P(2) 87.2(5),
P(1)-C(1)-P(2) 107.4(5), P(1)-C(2)-P(3) 97.7(5), P(2)-C(3)-
P(3) 97.1(6).
significantly different from each other, as are the intracyclic
P-C distances. This suggests that one resonance form of each
compound is partially favored in the solid state, i.e., that in
which the P(1)-C(2) bond is double.
Conclusions
In summary, reactions of the triphosphacyclohexadienyl
anion, [MeP3C3But3]-, toward a series of group 13 and 14 halide
complexes have been investigated. Within the coordination
sphere of several group 13 element(I) and group 14 element-
(II) centers, the triphosphacyclohexadienyl ligand facilely
eliminates a phosphinidene fragment, PMe, to give homo- and
heteroleptic diphospholyl complexes. These have been structur-
ally characterized and the fluxional behavior of the group 14
complexes explored by variable-temperature NMR studies. In
contrast, treating [MeP3C3But3]- with Ph3SnCl does not lead
to a phosphinidene elimination process but instead to the first
example of a complex containing a structurally characterized
1,2-diphosphabicyclo[1.1.0]butane fragment. This was shown
to readily isomerize in solution at room temperature to an
unusual five-coordinate tin complex chelated by an unsaturated
triphosphabicyclic anion. The lead analogue of this compound
has also been reported. This study has highlighted the synthetic
versatility of [MeP3C3But3]-, which has been used as a precursor
to the diphospholyl anion, [1,3-P2C3But3]-, as a source of the
phosphinidene fragment, PMe, and as a reagent for the formation
of novel group 14-organophosphorus cage complexes.
0.0 ppm (31P NMR), or external SnMe4, δ 0.0 ppm (119Sn NMR).
Mass spectra were recorded using a VG Fisons Platform II
instrument operating under APCI conditions or were obtained from
the EPSRC National Mass Spectrometric Service at Swansea
University. IR spectra were recorded using a Nicolet 510 FT-IR
spectrometer as Nujol mulls between NaCl plates. Melting points
were determined in sealed glass capillaries under argon and are
uncorrected. Microanalyses were obtained from Medac Ltd. P3C3-
But330 and “GaI”31 were synthesized by literature procedures. All
other reagents were used as received.
Preparation of [Ga(P2C3But3)] (2). To a solution of P3C3But3
(0.15 g, 0.5 mmol) in hexane (20 mL) was added a solution of
MeLi (0.5 mmol in 2 mL of diethyl ether) at -78 °C. A color
change from yellow to orange was observed. The solution was slow-
ly warmed to ambient temperature and stirred for 2 h. Volatiles
were removed in vacuo, and the residue was dissolved in hexane
(10 mL). This was added to a suspension of “GaI” (0.13 g,
0.5 mmol) in hexane (10 mL) at - 80 °C. The resultant suspension
was warmed to ambient temperature and stirred for 16 h, after which
the color changed from orange to brown. Volatiles were removed
in vacuo, and the residue was extracted in hexane (5 mL), filtered,
and placed at -30 °C overnight to yield 2 as a yellow powder
(98 mg, 58%). Mp: 221-226 °C dec. 1H NMR (300 MHz, C6D6,
298 K): δ 1.76 (s, 9H, PC(But)P), 1.79 (s, 18H, P{C(But)}2P).
31P{1H} NMR (121.7 MHz, C6D6, 298 K): δ 189.2 (s). IR (Nujol)
Experimental Section
General Methods. All manipulations were carried out using
standard Schlenk and glovebox techniques under an atmosphere
of high-purity argon. Hexane and THF were distilled over Na/K
1
alloy. H, 31P, and 119Sn NMR spectra were recorded on either
(30) Tabellion, F.; Nachbauer, A.; Leininger, S.; Peters, C.; Preuss, F.;
Regitz, M. Angew. Chem., Int. Ed. 1998, 37, 1233.
(31) Green, M. L. H.; Mountford, P.; Smout, G. J.; Peel, S. R. Polyhedron
1990, 9, 2763.
Bruker DPX400, Bruker AMX 500, or JEOL Eclipse 300 spec-
trometers in deuterated solvents and were referenced to the residual
1H resonances of the solvent used (1H), external 85% H3PO4, δ

Synthesis of 1,3-Diphosphacyclopentadienyl Complexes
Organometallics, Vol. 25, No. 20, 2006 4805
ν/cm-1: 1457 (s), 1378 (s), 1262 (s), 1201 (s), 1125 (s), 1019 (s),
831 (m). MS EI: m/z (%) 339.1 [M+, 15]. Anal. Calc for C15H27-
GaP2: C 53.14, H 8.03. Found: C 53.01, H 7.98.
(NAr)2H+, 100]. Anal Calc for C52H83N3SnP2: C 67.09, H 8.99, N
4.51. Found: C 66.70, H 8.95, N 4.50.
Preparation of [{(cis-2,6-Me2C5H8N)C(NAr)2}Sn(P2C3But3)]
(8). A solution of Li[MeP3C3But3] (0.5 mmol) in hexane (10 mL)
was prepared in-situ as described above. This was added to [{(cis-
2,6-Me2C5H8N)C(NAr)2}SnCl] (330 mg, 0.53 mmol) suspended in
hexane (30 mL) at -78 °C. The resultant mixture was stirred for
18 h, after which volatiles were removed in vacuo. The residue
was extracted with hexane (10 mL) and filtered, and the filtrate
was cooled to -30 °C to yield 8 as yellow crystals (82 mg, 18%).
Mp: 177-179 °C dec. 1H NMR (400 MHz, C6D6, 298 K): δ 0.92-
1.55 (m, 6H, CH2), 0.90 (d, 6H, 3JHH ) 6.9 Hz, NC(H)CH3), 1.36
Preparation of [Tl(P2C3But3)] (4). A solution of Li[MeP3C3-
But3] (0.5 mmol) in hexane (10 mL) was prepared in-situ as
described above. This was added to a suspension of TlCl (0.12 g,
0.5 mmol) in hexane (10 cm3) at -80 °C. The resultant suspension
was warmed to ambient temperature and stirred for 16 h, after which
the color changed from orange to green. Volatiles were removed
in vacuo, and the residue was extracted in hexane (5 cm3), filtered,
and placed at -30 °C overnight to yield 4 as a yellow powder.
Crystals suitable for the X-ray diffraction experiment were grown
by sublimation of this powder at reduced pressure (ca. 100 °C, 10-5
3
(s, 9H, PC(But)P), 1.42 (d, 12H, JHH ) 6.7 Hz, CH(CH3)2), 1.65
3
(s, 18H, P{C(But)}2P), 1.68 (d, 12H, JHH ) 6.7 Hz, CH(CH3)2),
1
mmHg) (170 mg, 67%). Mp: 198-200 °C dec. H NMR (300
3
MHz, C6D6, 298 K): δ 1.42 (s, 9H, PC(But)P), 1.56 (s, 18H, P{C-
(But)}2P). 31P{1H} NMR (121.7 MHz, C6D6, 298 K): δ 190.8 (d,
1JPTl ) 159 Hz). IR (Nujol) ν/cm-1: 1633 (m), 1455 (s), 1380 (s),
1261 (s), 1095 (s), 1022 (s), 803 (s). MS EI: accurate mass calc
for 205TlP2C15H27 474.1327, found 474.1327. Anal Calc for C15H27-
TlP2: C 38.03, H 5.74. Found: C 37.95, H 5.69.
3.75 (sept., 4H, JHH ) 6.7 Hz, CH(CH3)2), 3.95 (m, 2H, NCH),
7.12-7.40 (m, 6H, ArH). 31P{1H} NMR (121.7 MHz, C6D6, 298
1
K): δ 190.1 (br s, JPSn ) 88 Hz). IR (Nujol) ν/cm-1: 1616 (m),
1585 (m), 1455 (s), 1359 (s), 1236 (m), 1026 (s). MS APCI: m/z
(%) 476 [(Me2C5H8N)C(NAr)2H+, 100]. Anal Calc for C47H75N3-
SnP2: C 65.43, H 8.76, N 4.87. Found: C 64.74, H 8.46, N 4.65.
Preparation of [Ph3Sn(η1-C-MeP3C3But3)] (9). A solution of
Li[MeP3C3But3] (0.5 mmol) in hexane (10 mL) was prepared in-
situ as described above. This was added to a solution of Ph3SnCl
(0.19 g, 0.5 mmol) in hexane (20 mL) at -78 °C. The resultant
mixture was warmed to 25 °C and stirred for 4 h, after which
volatiles were removed in vacuo. The residue was extracted with
hexane (10 mL) and filtered, and the filtrate was cooled to -30 °C
to yield 9 as colorless crystals (245 mg, 74%). Mp: 134-136 °C
dec. 1H NMR (400 MHz, C6D6, 298 K): δ 0.92 (s, 9H, But), 1.20
NB: [In(P2C3But3)] (3) was prepared by a similar procedure
(yield 71%), and its spectroscopic data were found to be identical
with that reported in the literature.13
Preparation of [Sn(P2C3But3)2] (5). A solution of Li[MeP3C3-
But3] (0.5 mmol) in hexane (10 mL) was prepared in-situ as
described above. This was added to SnCl2 (50 mg, 0.26 mmol)
suspended in THF (30 mL) at ambient temperature. The resultant
mixture was stirred for 4 days, after which volatiles were removed
in vacuo. The residue was extracted with hexane (5 mL), filtered,
and concentrated to ca. 2 mL. Cooling to -30 °C yielded 5 as a
pale yellow crystalline solid (16 mg, 9%). Mp: 174-176 °C dec.
1H NMR (300 MHz, C6D6, 298 K): δ 1.35 (s, 18H, PC(But)P),
1.37 (s, 36H, P{C(But)}2P). 31P{1H} NMR (121.7 MHz, C6D6, 298
K): δ 196.9 (s). IR (Nujol) ν/cm-1: 1456 (s), 1363 (s), 1260 (s),
1218 (s), 1098 (s), 937 (w), 868 (m), 797 (s), 722 (m), 668 (m).
MS APCI: m/z (%) 389.1 [M+ - P2C3But3, 100]. Anal Calc for
C30H54SnP4: C 54.81, H 8.28. Found: C 54.55, H 8.26.
2
(s, 9H, But), 1.26 (s, 9H, But), 1.31 (d, 3H, JPH ) 11 Hz, PMe),
7.12-7.86 (m, 15H, ArH). 31P{1H} NMR (121.7 MHz, C6D6, 298
K): δ -284.7 (dd, 1JPP ) 184.5 Hz, 2JPP ) 12.0 Hz, P3), -8.4 (d,
2
2
1JPP ) 184.5 Hz, P2), 22.4 (d, JPP ) 12.0 Hz, JPSn ) 193 Hz,
P1). IR (Nujol) ν/cm-1: 1461 (s), 1362 (s), 1259 (m), 1197 (m),
1021 (m). MS EI: m/z (%) 666 [M+, 8], 315 [MeP3C3But3+, 100].
Anal Calc for C34H45SnP3: C 61.38, H 6.82. Found: C 60.95, H
6.65.
Preparation of [Ph3Sn(η2-P,P-MeP3C3But3)] (10). This com-
pound was prepared similarly to 9 except the reaction mixture was
stirred at 25 °C for 56 h before workup (284 mg, 86%). Mp: 201-
Preparation of [Pb(P2C3But3)2] (6). A solution of Li[MeP3C3-
But3] (0.5 mmol) in hexane (10 mL) was prepared in-situ as
described above. This was added to PbCl2 (80 mg, 0.29 mmol)
suspended in THF (30 mL) at ambient temperature. The resultant
mixture was stirred for 4 days, after which volatiles were removed
in vacuo. The residue was extracted with hexane (5 mL), filtered,
and concentrated to ca. 2 mL. Cooling to - 30 °C yielded 6 as a
1
205 °C dec. H NMR (400 MHz, C6D6, 298 K): δ 0.18 (s, 9H,
2
But), 0.82 (s, 18H, But), 1.62 (d, 3H, JPH ) 12 Hz, PMe), 6.89-
7.92 (m, 15H, ArH). 31P{1H} NMR (121.7 MHz, C6D6, 298 K): δ
35.3 (s, PMe), 87.1 (s, 1JP Sn ) 732 Hz, 1JP Sn ) 767 Hz, P2Sn).
117
119
119Sn{1H} NMR (186.5 MHz, C6D6, 298 K): δ -85.5 (tr, JP
1
119Sn
1
) 767 Hz). IR (Nujol) ν/cm-1: 1462 (s), 1365 (s), 1260 (m), 1089
(m), 1021 (m), 802 (m). MS EI: m/z (%) 666 [M+, 12], 315
[MeP3C3But3+, 100]. MS EI: accurate mass calc for C34H45SnP3
666.1751, found 666.1753. Anal Calc for C34H45SnP3: C 61.38, H
6.82. Found: C 61.23, H 6.64.
yellow crystalline solid (24 mg, 13%). Mp: 88-91 °C dec. H
NMR (300 MHz, C6D6, 298 K): δ 1.56 (s, 18H, PC(But)P), 1.58
(s, 36H, P{C(But)}2P). 31P{1H} NMR (121.7 MHz, C6D6, 298 K):
1
δ 202.6 (s, JPPb ) 215 Hz). IR (Nujol) ν/cm-1: 1644 (m), 1460
(s), 1377 (s), 1260 (s), 1096 (s), 1022 (s), 801 (s). MS EI: accurate
mass calc for C30H54P4208Pb 746.2937, found 746.2942. Anal Calc
for C30H54PbP4: C 48.31, H 7.30. Found: C 48.23, H 7.28.
Preparation of [Ph3Pb(η2-P,P-MeP3C3But3)] (11). A solution
of Li[MeP3C3But3] (0.5 mmol) in hexane (10 mL) was prepared
in-situ as described above. This was added to a solution of Ph3-
PbCl (0.24 g, 0.5 mmol) in hexane (20 mL) at -78 °C. The resultant
mixture was warmed to 25 °C and stirred for 4 h, after which
volatiles were removed in vacuo. The residue was extracted with
hexane (10 mL) and filtered, and the filtrate was cooled to -30 °C
to yield 11 as orange crystals (90 mg, 24%). Mp: 143-145 °C
dec. 1H NMR (400 MHz, C6D6, 298 K): δ 0.23 (s, 9H, But), 0.87
(s, 18H, But), 1.64 (d, 3H, 2JPH ) 9 Hz, PMe), 7.01-8.12 (m, 15H,
Preparation of [{Cy2NC(NAr)2}Sn(P2C3But3)] (7). A solution
of Li[MeP3C3But3] (0.5 mmol) in hexane (10 mL) was prepared
in-situ as described above. This was added to [{Cy2NC(NAr)2}-
SnCl] (350 mg, 0.50 mmol) suspended in hexane (30 mL) at -78
°C. The resultant mixture was stirred for 18 h, after which volatiles
were removed in vacuo. The residue was extracted with hexane
(10 mL) and filtered, and the filtrate cooled to -30 °C to yield 7
as yellow crystals (98 mg, 21%). Mp: 183-185 °C dec. 1H NMR
(400 MHz, C6D6, 298 K): δ 0.82-1.52 (m, 20H, CH2), 1.35 (s,
3
ArH). 31P{1H} NMR (121.7 MHz, C6D6, 298 K): δ 36.3 (s, JPPb
1
3
9H, PC(But)P), 1.48 (d, 12H, JHH ) 6.7 Hz, CH(CH3)2), 1.64 (s,
) 120 Hz, PMe), 121.0 (s, JPPb ) 1967 Hz, P2Pb). IR (Nujol)
ν/cm-1: 1462 (s), 1365 (s), 1265 (m), 1013 (m), 915 (m). MS EI:
m/z (%) 755 [M+, 15], 315 [MeP3C3But3+, 100]. Anal Calc for
C34H45PbP3: C 54.17, H 6.02. Found: C 53.89, H 5.98.
18H, P{C(But)}2P), 1.70 (d, 12H, 3JHH ) 6.7 Hz, CH(CH3)2), 3.52
(m, 2H, NCH), 3.73 (sept., 4H, 3JHH ) 6.7 Hz, CH(CH3)2), 7.10-
7.32 (m, 6H, ArH). 31P{1H} NMR (121.7 MHz, C6D6, 298 K): δ
192.3 (br s). IR (Nujol) ν/cm-1: 1612 (m), 1584 (m), 1455 (s),
1377 (s), 1245 (m), 1018 (s). MS APCI: m/z (%) 544 [Cy2NC-
X-ray Crystallography. Crystals of 4-11 suitable for X-ray
structural determination were mounted in silicone oil. Crystal-

Table 1. Summary of Crystallographic Data for Compounds 4-11
4
5
6
7
8
9
10
11
empirical formula
fw
C15H27P2Tl
473.68
C30H54P4Sn
657.30
C30H54P4Pb
745.80
C52H83N3P2Sn
930.84
C47H75N3P2Sn
862.73
C34H45P3Sn
665.30
C34H45P3Sn
665.30
C34H45P3Pb
753.80
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
C2/c
34.278(7)
18.508(4)
11.287(2)
90
97.78(3)
90
7095(2)
16
monoclinic
P21/n
9.1210(2)
18.1260(3)
20.4400(4)
90
98.737(1)
90
3340.08(11)
4
monoclinic
P21/n
9.1190(2)
18.1130(3)
20.6030(4)
90
98.703(1)
90
3363.87(11)
4
triclinic
P1h
monoclinic
P21/c
19.036(4)
14.100(3)
19.674(4)
90
117.60(3)
90
4679.9(16)
4
triclinic
P1h
monoclinic
P21/c
10.548(2)
16.508(3)
19.768(4)
90
101.65(3)
90
3371.2(12)
4
monoclinic
P21/c
10.659(2)
16.457(3)
19.767(4)
90
101.43(3)
90
3398.9(12)
4
13.249(3)
17.212(3)
22.615(5)
87.67(3)
83.94(3)
89.49(3)
5124.0(18)
4
8.4140(17)
11.287(2)
17.484(4)
104.26(3)
90.60(3)
93.64(3)
1605.4(6)
2
R (deg)
â (deg)
γ (deg)
vol (Å3)
Z
F(calcd) (g cm-3
)
1.774
9.271
3648
1.307
0.973
1376
1.473
5.222
1504
1.207
0.596
1984
1.224
0.648
1832
1.376
0.967
688
1.311
0.921
1376
1.473
5.125
1504
µ (mm-1
F(000)
)
cryst size (mm)
θ range (deg)
no. of reflns collected
Rint
0.10 × 0.05 × 0.05
2.94 to 25.00
19 355
0.20 × 0.08 × 0.07
3.01 to 27.09
29 737
0.20 × 0.08 × 0.07
3.00 to 27.09
31 995
0.15 × 0.10 × 0.08
2.92 to 25.50
28 902
0.25 × 0.15 × 0.12
3.09 to 27.00
19 460
0.45 × 0.45 × 0.25
3.04 to 27.45
20 834
0.20 × 0.18 × 0.08
3.16 to 26.88
15 150
0.20 × 0.18 × 0.08
3.14 to 26.00
12 501
0.1065
0.0734
0.0904
0.0551
0.0313
0.0444
0.0431
0.0416
no. of data/restraints/
params
6221/0/335
7334/6/334
7397/6/334
18811/0/1079
10167/0/497
7195/0/354
6926/36/354
6630/36/354
goodness of fit on F2
R1 indices [I > 2σ(I)]a
wR2 indices (all data)b
largest peak and
1.119
0.0854
0.2077
3.201 (near Tl1) and
-2.379 (near Tl2)
1.019
0.0415
0.0972
0.569 and -1.179
1.022
0.0427
0.1005
1.169 and -1.289
1.054
0.0693
0.1158
0.985 and -0.530
1.029
0.0550
0.1368
2.420 (near Sn1) and
-1.429
1.013
0.0238
0.0574
0.523 and -0.480
1.061
0.0678
0.1614
2.512 (near Sn1) and
-0.989
1.121
0.0697
0.1329
2.313 (near Pb1) and
-1.248
hole (e A-3
)
2
2
2 2
a R1(F) ) {∑(|Fo| - |Fc|)/∑|Fo|} for reflections with Fo > 4(σ(Fo)). b wR2(F2) ) {∑w(|Fo| - |Fc| )2/∑w|Fo | }1/2 where w is the weight given each reflection.

Synthesis of 1,3-Diphosphacyclopentadienyl Complexes
Organometallics, Vol. 25, No. 20, 2006 4807
lographic measurements were made using a Nonius Kappa CCD
diffractometer using a graphite monochromator with Mo KR
radiation (λ ) 0.71073 Å). The data were collected at 150 K, and
the structures were solved by direct methods and refined on F2 by
full matrix least squares (SHELX97)32 using all unique data. All
non-hydrogen atoms are anisotropic with hydrogen atoms included
in calculated positions (riding model). Crystal data, details of data
collections, and refinement are given in Table 1.
for M.D.F.) and the Royal Society (postdoctoral fellowship for
G.J.) for financial support. We also gratefully acknowledge the
EPSRC Mass Spectrometry Service, Swansea.
Supporting Information Available: Crystallographic data as
CIF files for 4-11, [{Cy2NC(NAr)2}SnCl], and [{(cis-Me2C5H8N)C-
(NAr)2}SnCl]; synthetic, spectroscopic, and crystallographic details
for [{Cy2NC(NAr)2}SnCl] and [{(2,6-Me2C5H8N)C(NAr)2}SnCl].
This material is available free of charge via the Internet at
http://pubs.acs.org.
Acknowledgment. We thank the EPSRC (partial studentship
for M.B., studentship for D.P.M., and postdoctoral fellowship
(32) Sheldrick, G. M. SHELX-97; University of Go¨ttingen, 1997.
OM0605581