General routes to alkyl phosphatrioxaadamantane ligands

Article abstract of DOI:10.1021/om800141y

The secondary phosphine CgPH (CgP = 6-phospha-2,4,8-trioxa-1,3,5,7- tetramethyladamantyl group) is made in 50% yield by a modification of the literature method (avoiding high pressures of PH₃) by bubbling PH₃ through an acidified sol

Full text of DOI:10.1021/om800141y

3216
Organometallics 2008, 27, 3216–3224
General Routes to Alkyl Phosphatrioxaadamantane Ligands
Joanne H. Downing, Joe¨lle Floure, Katie Heslop, Mairi F. Haddow, Jonathan Hopewell,
Matteo Lusi, Hirahataya Phetmung, A. Guy Orpen, Paul G. Pringle,* Robert I. Pugh, and
Damaris Zambrano-Williams
School of Chemistry, UniVersity of Bristol, Cantocks Close, Bristol BS8 1TS, U.K.
ReceiVed February 15, 2008
The secondary phosphine CgPH (CgP ) 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamantyl group)
is made in 50% yield by a modification of the literature method (avoiding high pressures of PH3) by
bubbling PH3 through an acidified solution of 2,4-pentanedione at 0 °C. Under similar conditions the
ethyl analogue EtCgPH is formed from 3,5-heptanedione in 75% yield. The halophosphines CgPCl and
CgPBr are made by treatment of CgPH with N-halosuccinimide. CgPBr is also made by treatment of
CgPH with Br2. Three methods are described for the synthesis of CgPR, where R ) alkyl: (a) the previously
reported acid-catalyzed condensation reaction of RPH2 with 2,4-pentanedione, which has been extended
i
to R ) Pr; (b) treatment of CgP(BH3)Li with RX followed by borane deprotection with Et2NH, which
i
has been used for R ) Pr, benzyl, n-C20H41; (c) treatment of CgPBr with RMgX, which has been used
i
for R ) Pr, Me. The complexes [PtCl2(CgPH)2] (1), [PdCl2(CgPH)2] (2), [PdCl2(CgPR)2] (where R )
i
iPr (3a), Cy (3b)), and [PtCl2(CgPR)2] (where R ) Pr (4a), Cy (4b), n-C20H41 (4c)) are described. The
crystal structures of CgPH, CgPCl, [CgP(CH2Ph)2]Br, CgP(n-C20H41), and complexes 1, 3b, and 4c are
reported. From the ν(CO) values for trans-[RhCl(CO)(CgPX)2], the σ-donor/π-acceptor properties of
i
CgPX are in the order X ) Pr > Me > Ph > H > Cl.
Chart 1. Enantiomeric Structures of the CgP Moiety
Introduction
The first metal complexes of ligands containing the 6-phospha-
2,4,8-trioxa-1,3,5,7-tetramethyladamantyl group (denoted CgP
throughout; see Chart 1) were reported in the late 1990s,1 and since
then, several examples have emerged of the applications of CgP
ligands in metal complex catalyzed hydroformylation,2,3 alkene
carbonylation,4 C-C coupling,5,6 and hydrogenation.7 We have
* To whom correspondence should be addressed. E-mail:
paul.pringle@bristol.ac.uk.
(1) (a) Gee, V.; Orpen, A. G.; Phetmung, H.; Pringle, P. G.; Pugh, R. I.
Chem. Commun. 1999, 901. (b) Suykerbuyk, J. C. L. J.; Drent, E.; Pringle,
P. G. World Pat. WO9842717, 1998. (to Shell).
(2) Baber, R. A.; Clarke, M. L.; Heslop, K. M.; Marr, A. C.; Orpen,
A. G.; Pringle, P. G.; Ward, A.; Zambrano-Williams, D. E. Dalton Trans.
2005, 1079.
shown previously that the rigid CgP substituent is at least as bulky
as tBu2P and resembles (PhO)2P in terms of σ/π-bonding charac-
teristics.2 It is this unusual combination of stereoelectronic char-
acteristics which might be at the root of the remarkable catalytic
performance of ligands containing CgP. The C1 symmetry of the
CgP group means that enantiomers of its derivatives, labeled R
and ꢀ in Chart 1, are formed.
Previously, CgPR species (R ) alkyl, aryl) have been
synthesized by the reaction of RPH2 with acetylacetone,2,8 by
metal-catalyzed RBr substitutions using CgPH,6 or by radical-
initiated P-H addition of CgPH to alkene.6,9 We report here
general methods for the synthesis of monodentate ligands of
the type CgPR (R ) alkyl) from the secondary phosphine CgPH
or bromophosphine CgPBr. The stereoelectronic properties of
these ligands are assessed from the structural and spectroscopic
properties of some coordination complexes of CgPH and CgPR.
(3) (a) Clarke, M. L.; Roff, G. J. Chem. Eur. J. 2006, 12, 7979. (b)
Almeida Lenero, K. Q.; Drent, E.; van Ginkel, R.; Pugh, R. I. World Pat.
WO2005058788, 2005. (to Shell). (c) Ahlers, W.; Slany, M. World Pat.
WO2001085662,2001.(toBASF).(d)Ahlers,W.;WorldPat.WO2001085661,
2001. (to BASF).
(4) (a) Pugh, R. I.; Pringle, P. G.; Drent, E. Chem. Commun. 2001, 1476.
(b) Butler, I. R.; Baker, P. K.; Eastham, G. R.; Fortune, K. M.; Horton,
P. N.; Hursthouse, M. B. Inorg. Chem. Commun. 2004, 7, 1049. (c) Drent,
E.; Pringle, P. G.; Pugh, R. I. World Pat. WO2001028972, 2001. (to Shell).
(d) Eastham, G. World Pat. WO2005118519, 2005. (to Lucite). (e) Eastham,
G.; Tindale, N. World Pat. WO2005079981, 2005. (to Lucite). (f) Drent,
E.; Ernst, R.; Jager, W. W. World Pat. WO2004103948, 2004. (to Shell).
(g) Eastham, G. World Pat. WO2004024322, 2004. (to Lucite). (h) Drent,
E.; van der Made, R. H.; Pugh, R. I. World Pat. WO2003070679, 2003. (to
Shell). (i) Drent, E.; van der Made, R. H.; Pringle, P. G.; Pugh, R. I. World
Pat. WO2003070370, 2003. (to Shell). (j) Sava, X.; Slany, M.; Ro¨per, M.
World Pat. WO2003031457, 2003. (to BASF). (k) Slany, M.; Schaefer,
M.; Ro¨per, M. Ger Pat. DE10228293, 2003. (to BASF). (l) Schaefer, M.;
Slany, M.; Zeller, E.; Ro¨per, M. World Pat. WO2002026382, 2002. (to
BASF).
Results and Discussion
Cage Phosphine Synthesis. The parent cage phosphine CgPH
was originally made by Epstein and Buckler8 in 81% yield in
(5) (a) Gerristma, D.; Brenstrum, T.; McNulty, J.; Capretta, A. Tetra-
hedron Lett 2004, 45, 8319. (b) Brenstrum, T.; Gerristma, D. A.; Adjabeng,
G. M.; Frampton, C. S.; Britten, J.; Robertson, A. J.; McNulty, J.; Capretta,
A. J. Org. Chem. 2004, 69, 7635. (c) Ohnmacht, S. A.; Brenstrum, T.;
Bleicher, K. H.; McNulty, J.; Capretta, A. Tetrahedron Lett. 2004, 45, 5661.
(d) Adjabeng, G. M.; Brenstrum, T.; Frampton, C. S.; Robertson, A. J.;
Hillhouse, J.; McNulty, J.; Capretta, A. J. Org. Chem. 2004, 69, 5082.
(6) Adjabeng, G. M.; Brenstrum, T.; Wilson, J.; Frampton, C. S.; Robertson,
A.; Hillhouse, J.; McNulty, J.; Capretta, A. Org. Lett. 2003, 5, 953.
(7) Hadovic, A.; Lough, A. J.; Morris, R. H.; Pringle, P. G.; Zambrano-
Williams, D. E. Inorg. Chim. Acta 2006, 359, 2864.
(8) Epstein, M.; Buckler, S. H. J. Am. Chem. Soc. 1961, 83, 3279.
(9) Cunningham, T. J.; Elsegood, M. R. J.; Paul, F.; Kelly, P. F.; Martin,
B.; Smith, M. B.; Staniland, P. M. Eur. J. Inorg. Chem. 2008, 2326.
10.1021/om800141y CCC: $40.75
2008 American Chemical Society
Publication on Web 06/11/2008

Alkyl Phosphatrioxaadamantane Ligands
Organometallics, Vol. 27, No. 13, 2008 3217
Scheme 1
Figure 1. Crystal structure of CgPH showing 50% probability
ellipsoids. All hydrogen atoms except H1 are omitted for clarity.
Selected bond lengths (Å) and angles (deg): P1-C4 ) 1.865(2),
P1-C1 ) 1.872(2), P1-H1 ) 1.30(4); C4-P1-C1 ) 93.54(9),
C4-P1-H1 ) 95.0(17), C1-P1-H1 ) 101.8(17).
less than 1 h from the acid-catalyzed condensation reaction of
acetylacetone with PH3 under 2-3 atm pressure (eq 1). We
found that CgPH was precipitated in 15% yield when PH3 was
bubbled through an acidified aqueous solution of acetylacetone
at atmospheric pressure for 7 h at 25 °C. In an attempt to
improve this yield, the PH3 addition was carried out at higher
temperatures, but this led to lower yields, and at 80 °C, no CgPH
precipitate was observed. Instead, a complicated mixture of
products was formed, as evidenced by the 10 significant 31P
resonances across the range -40 to +20 ppm, none of which
corresponded to CgPH. Under atmospheric pressure, the best
yields of CgPH (50%) were obtained when the reaction was
conducted at 0 °C (see Experimental). Under similar conditions
we have also obtained the previously reported8 cage phosphine
EtCgPH (eq 1) in 75% yield (see the Experimental Section).
The air sensitivity of the EtCgPH oil contrasts with the air
stability of the crystalline CgPH.
The literature route to CgPR (R ) CH2CHMe2, n-C8H17,
c-C6H11)8,11 is by the acid-catalyzed condensation reaction of
primary phosphines RPH2 with acetylacetone (eq 2), and this
was used to make the new compound CgPiPr, though the
reaction is slow (11 days) and the yield modest (41%). Another
disadvantage of the route shown in eq 2 is that for each CgPR,
the corresponding noxious primary phosphine RPH2 has to be
used. To avoid this, we have sought to use CgPH (which is
now commercially available) as a starting material for general
syntheses of CgPR.
Our first strategy was to attempt to make CgPR via quaterni-
sation of CgPH (Scheme 1). Thus, a 1:1 mixture of CgPH and
PhCH2Br (BzBr) was refluxed in MeCN but after 6 days, less than
10% quaternization to [CgPH(Bz)]Br was apparent from the 31P
NMR spectrum of the solution. Addition of NEt3 to the NMR
sample did give a 31P NMR signal consistent with the desired
product CgPBz (δP -24.4). However, since benzyl bromide is a
particularly reactive electrophile, its slowness of reaction with
CgPH led us to abandon this as a potentially general route.
A small amount (2% yield) of crystalline material separated
from the MeCN solution of the quaternisation reaction mixture.
The spectroscopic data (see the Experimental Section) and X-ray
crystallography revealed that this product was [CgPBz2]Br,
presumably formed by quaternization of CgPBz with BzBr.
The complicated mechanism of the cage formation reaction
has been discussed previously,1,8,10 with many intermediates
purported to be involved in a series of equilibria. The formation
of CgPH is probably driven by its precipitation, and the
improved yields in ice cold aqueous media are likely a
consequence of the higher solubility of the gaseous PH3 and
the lower solubility of CgPH at lower temperatures.
Crystals of CgPH suitable for X-ray crystallography were
obtained by slow cooling of its MeOH solution (Figure 1). CgPH
crystallizes in the space group P21/c with one molecule in the
asymmetric unit; this crystal structure has previously been
reported at a different temperature.6
j
[CgPBz2]Br crystallizes in the space group P1 with one molecule
in the asymmetric unit, indicating that the crystal structure
contains a racemic mixture of the R and ꢀ enantiomers of the
cage phosphine (Figure 2). The phosphonium cage P-C bond
lengths of 1.856(2) and 1.851(2) Å are slightly shorter than those
(1.865-1.883 Å) found in the crystal structures of the uncom-
(10) Bekiaris, G.; Lork, E.; Offermann, W.; Roschenthaler, G. V. Chem.
Ber. 1997, 130, 1547.
(11) Carraz, C.-A.; Stephan, D. W. Organometallics 2000, 19, 3791.

3218 Organometallics, Vol. 27, No. 13, 2008
Downing et al.
Figure 3. Crystal structure of CgP(n-C20H41) showing 50% prob-
ability ellipsoids. All hydrogens and all except the first four carbons
of the C20H41 substituent are omitted for clarity. Selected bond
lengths (Å) and angles (deg): P1-C11 ) 1.854(2), P1-C1 )
1.875(2), P1-C4 ) 1.883(2); C11-P1-C1 ) 101.66(10),
C11-P1-C4 )102.08(9), C1-P1-C4 )92.59(10), C1-P1-C11-C12
) -101.10(16), C4-P1-C11-C12 ) 163.66(15), P1-C11-C12-C13
) -70.1(2).
The low nucleophilicity of CgPH (evident from its slow
reaction with BzBr) can be rationalized in terms of its bulk and
the electron-withdrawing nature of the cage. Lithiation of its
borane adduct CgPH(BH3), prepared by treatment of CgPH with
BH3 in THF (Scheme 2), provided a versatile nucleophilic
source of the CgP group. Thus, treatment of CgPH(BH3) with
n-BuLi gave CgPLi(BH3) (δP -32.5, J(PB) ) 31 Hz), which
reacted smoothly with BzBr to give CgP(Bz)(BH3), and upon
borane deprotection with Et2NH, the desired CgPBz was
obtained in 62% overall yield. On occasion, after the lithiation
step, the unreactive bis(borane) species [CgP(BH3)2]Li (broad
signal at δP 3.1) was detected. [CgP(BH3)2]Li is formed upon
treatment of CgPLi(BH3) with BH3 and therefore may arise from
the presence of an excess of BH3, but it was also observed to
form slowly in solutions of CgPLi(BH3), presumably by
abstraction of BH3 from another CgPLi(BH3). Therefore, to
minimize the formation of [CgP(BH3)2]Li, the presence of free
BH3 was avoided and CgPLi(BH3) was generated in dilute
solution and used immediately (see the Experimental Section).
The nucleophilic route to CgPBz (Scheme 2) has been
generalized to make the CgPR compounds featuring the primary
and secondary alkyl substituents shown in eq 3. This route (eq
3) avoids the need for RPH2 used in the route shown in eq 2.
The 71% yield of CgPiPr obtained after 24 h via the nucleophilic
route (eq 3) is superior to the 41% yield of the same CgPiPr
obtained after 11 days via the hydrophosphination/condensation
route (eq 2).
Figure 2. Crystal structure of [CgPBz2]Br showing 50% probability
ellipsoids. All hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): P1-C18 ) 1.8131(18), P1-C11 )
1.8169(19), P1-C2 ) 1.851(2), P1-C9 ) 1.856(2); C18-P1-C11
) 107.52(9), C18-P1-C2 ) 113.70(9), C11-P1-C2 ) 113.72(9),
C18-P1-C9 ) 108.49(8), C11-P1-C9 ) 116.00(9), C2-P1-C9
) 97.28(9), P1-C11-C12-C13 ) 84.1(2), P1-C18-C19-C20
) 104.8(2).
Scheme 2
plexed cage phosphines described here. The benzyl groups are
orientated such that the torsion angles C18-P1-C11-C12 and
C11-P1-C18-C19 are 151.1 and 66.1°, respectively.
Crystals of CgPC20H41 were grown from a saturated CDCl3
solution have space group P1 and contain a racemic mixture of
R and ꢀ enantiomers (Figure 3). The first P-C-C-C torsion
j

Alkyl Phosphatrioxaadamantane Ligands
Organometallics, Vol. 27, No. 13, 2008 3219
Scheme 3
Figure 4. Crystal structure of CgPCl showing 50% probability
ellipsoids. Most hydrogen atoms are omitted for clarity. Selected
bond lengths (Å) and angles (deg): P1-C1 ) 1.871(3), P1-C4 )
1.871(3), P1-Cl1 ) 2.0754(11); C1-P1-C4 ) 93.70(13),
C1-P1-Cl1 ) 101.42(10), C4-P1-Cl1 ) 101.61(10).
The potential utility of CgPBr as an electrophilic precursor
to CgPR was shown by treatment of CgPBr with RMgBr to
give CgPR (R ) Me, Pr) in good yields (eq 5).
i
in the long C20 chain at C12-C13 is gauche at -70.1°, but all
other C-C-C-C torsion angles which follow are anti. The
carbon chains are packed such that the planes in which all the
carbons in the long chains are packed are parallel.
Halophosphines are widely used precursors to tertiary phos-
phines. The chlorophosphine CgPCl was made in over 90% yield
by treatment of CgPH with N-chlorosuccinimide in CCl4 (eq
4). The conditions for this reaction need to be carefully
controlled to avoid incomplete conversion or overoxidation with
the formation of P(V) species (see the Experimental Section).
The bromophosphine CgPBr can be made similarly, but a more
convenient method is by treatment of CgPH with Br2 (eq 4).
The halophosphines CgPX have been fully characterized,
including a crystal structure of CgPCl.
In summary, we have accessed CgPiPr by the three routes
shown in Scheme 3 ((a) hydrophosphination/condensation, (b)
nucleophilic, and (c) electrophilic) and established each to be
general for CgPR.
Coordination Chemistry of CgPR. Addition of 2 equiv of
secondary phosphine CgPH to [PtCl2(cod)] in CH2Cl2 gave the
sparingly soluble cis-[PtCl2(CgPH)2] (1). The 31P{1H} NMR
spectrum showed 2 singlets (in 1:1 ratio) at 1.2 and 1.6 with
1J(PtP) of 3292 and 3299 consistent with the cis geometry and
the presence of rac (RR/ꢀꢀ) and meso (Rꢀ) diastereoisomers.
Similar diastereoisomerism is detected in the high field 31P NMR
spectra of many of the complexes reported here (see Experi-
mental) and is associated with the C1 symmetry of the CgPR
ligands (see Chart 1). The proton-coupled 31P NMR spectrum
of 1 showed two N doublets for the AA’XX’ spin system with
|1J(PH) + 3J(PH)| of 405 Hz, significantly larger than the J(PH)
of 190 Hz for free CgPH; similar increases in J(PH) have been
reported in other secondary phosphine complexes.12
Crystals of CgPCl were grown by slow evaporation of its
CCl4 solution. The P-C bond lengths in CgPCl (see Figure 4)
are similar to those in CgPH. The protons in the CH2 groups in
1
all the CgP ligands are diastereotopic, giving rise to four H
NMR signals, the multiplicity of which depends on the coupling
Crystals of 1 were grown by slow diffusion of a CH2Cl2
solution of [PtCl2(cod)] into a solution of CgPH in CH2Cl2
(Figure 5). Complex 1 crystallizes in space group Cc as the cis
and meso isomer and has approximate mirror symmetry with
the hydrogen substituents on the phosphorus atoms almost
perfectly eclipsed and pointing toward each other. This is likely
a consequence of the minimization of steric interactions between
the CgP moieties.
2
3
constants J(HH) and J(PH). Often these signals overlap, but
where they are resolved, they can be assigned by COSY NMR
spectroscopy (see the Experimental Section). The 1H NMR
spectra of CgPX (X ) H, Cl, Br) are similar, apart from one of
the CH2 signals which is significantly deshielded in the
halophosphines, resonating at δ 2.25 in CgPCl and δ 2.41 in
CgPBr compared to δ 1.73 in CgPH. The crystal structure of
CgPCl shows that one of the CH2 protons (H2A in Figure 4) is
close to the chlorine (Cl · · · H ) 2.73 Å), and since the rigidity
of the cage precludes significant conformational change in
solution, it is this proton that is assigned to the deshielded CH2
(12) Eberhard, M. R.; Carrington-Smith, E.; Drent, E. E.; Marsh, P. S.;
Orpen, A. G.; Phetmung, H.; Pringle, P. G. AdV. Synth. Catal. 2005, 347,
1345.
1
resonance in the H NMR spectra of CgPCl and CgPBr.

3220 Organometallics, Vol. 27, No. 13, 2008
Downing et al.
cyclohexyl groups are anti to each other; thus, the improper
torsion C11-P1 · · · P1A-C11A is 180°.
Crystals of 4c suitable for X-ray crystallography were grown
from CH2Cl2 (Figure 7). Complex 4c crystallizes as the trans
j
and meso (Rꢀ) isomer in the space group P1 with two
independent molecules in the asymmetric unit and, hence, four
independent C20 chains. The P-C-C-C and first C-C-C-C
conformations vary among the four chains, but all adopt
extended conformations so that the second and subsequent
C-C-C-C torsion angles are close to 180°. The C20 chains
pack so the planes formed by the carbons in three of the chains
lie roughly parallel to each other, whereas the fourth chain is
rotated at 90° to this. The alkyl groups are syn to each other:
i.e., the improper torsion C-P1 · · · P2-C is close to 0° in both
of the independent molecules.
Figure 5. Crystal structure of 1 showing 50% probability ellipsoids.
All hydrogen atoms are omitted for clarity, apart from the P-H
hydrogens. Selected bond lengths (Å) and angles (deg): Pt1-P1 )
2.2282(11), Pt1-P2 ) 2.2439(12), Pt1-Cl1 ) 2.3430(11), Pt1-Cl2
) 2.3605(11), P1-C17 ) 1.856(4), P1-C12 ) 1.869(4), P2-C2
) 1.866(4), P2-C7 ) 1.864(4); P1-Pt1-P2 ) 88.65(4),
P1-Pt1-Cl1 ) 91.07(4), P2-Pt1-Cl2 ) 92.42(4), Cl1-Pt1-Cl2
) 87.85(4).
In order to assess the bonding characteristics of CgPX, the
ν(CO) values (in CH2Cl2) for the carbonylrhodium complexes
5a-e were measured (see Chart 2). The order of increasing
ν(CO) is X ) iPr > Me > Ph > H > Cl, which is as expected
in terms of an increase in the electronegativity of the substituent,
leading to a decrease in the σ-donor and an increase in the
π-acceptor capacity of the ligand. The values also confirm the
relatively electron withdrawing nature of the CgP group
compared with other R2P groups;2 under the same conditions,
Addition of 2 equiv of CgPH to [PdCl2(cod)] in CH2Cl2 gave
trans-[PdCl2(CgPH)2] (2), as shown by the virtual triplets13
observed for several of the resonances in its 13C NMR spectrum
(see the Experimental Section for the characterization data).
The palladium(II) complexes 3a,b and platinum(II) complexes
4a-c were made by addition of the tertiary phosphines CgPR
to the appropriate dichlorometal precursor (see the Experimental
Section for the characterization data).
Crystals of 3b suitable for X-ray crystallography were grown
from CH2Cl2/hexane. Complex 3b crystallizes in space group
j
P1 with half a molecule in the asymmetric unit; the other half
of the molecule is related by inversion symmetry and thus the
complex is the trans and meso (R/ꢀ) isomer (see Figure 6). The
Figure 6. Crystal structure of trans-[PdCl2(CgPCy)2] (3b) showing
50% probability ellipsoids. All hydrogen atoms are omitted for
clarity. Selected bond lengths (Å) and angles (deg): Pd1-Cl1 )
2.2934(7), Pd1-P1 ) 2.3641(6), P1-C11 ) 1.858(2), P1-C4 )
1.890(2), P1-C1 ) 1.895(2); C11-P1-C4 ) 110.66(8), C11-
P1-C1 ) 102.30(8), C4-P1-C1 ) 93.38(8).
(13) (a) Redfield, D. A.; Nelson, J. H.; Cary, L. W. Inorg. Nucl. Chem.
Lett. 1974, 10, 727. (b) Pregosin, P. S.; Kunz, R. HelV. Chim. Acta 1975,
58, 423. (c) van den Beuken, E. K.; Meetsma, A.; Kooijman, H.; Spek,
A. L.; Feringa, B. L. Inorg. Chim. Acta 1997, 264, 171. (d) Andreasen,
L. V.; Simonsen, O.; Wernberg, O. Inorg. Chim. Acta 1999, 295, 153.

Alkyl Phosphatrioxaadamantane Ligands
Organometallics, Vol. 27, No. 13, 2008 3221
Figure 7. Crystal structure of trans-[PtCl2(CgPC20H41)2] (4c) showing 50% probability ellipsoids. All hydrogen atoms are omitted for
clarity. Selected bond lengths (Å): Pt1-Cl1 ) 2.298(3), Pt1-P2 ) 2.300(3), Pt1-Cl2 ) 2.317(3), Pt1-P1 ) 2.328(3), Pt2-P4 ) 2.291(4),
Pt2-P3 ) 2.300(4), Pt2-Cl3 ) 2.302(3), Pt2-Cl4 ) 2.332(3).
system15 in flame- and vacuum-dried glassware. MeOH was dried
over 3 Å molecular sieves and deoxygenated by N2 saturation.
Commercial reagents were used as supplied unless otherwise stated.
All phosphines were stored under nitrogen at room temperature.
The secondary phosphine CgPH can be obtained from Cytec but,
in this work, was made by the route described below. Most
complexes were stable to air in the solid state and were stored in
air at room temperature. The starting materials [PtCl2(cod)],16
for trans-[RhCl(CO){PPhn(C6F5)3-n}2], ν(CO)/cm-1 is 1965 (n
) 3), 1983 (n ) 2), 1996 (n ) 1), and 2005 (n ) 0).14
Chart 2
19
[PdCl2(cod)],17 [PdCl2(NCPh)2],18 and [RhCl(CO)2]2 were pre-
pared by literature methods. Elemental analyses were carried out
by The Microanalytical Laboratory of the School of Chemistry,
University of Bristol. Electron impact and fast atom bombardment
mass spectra were recorded by The Mass Spectrometry Service,
University of Bristol, on MD800 and Autospec instruments. Infrared
spectroscopy was carried out on a Perkin-Elmer 1600 Series FTIR
spectrometer. NMR spectra were measured on a JEOL GX 300,
JEOL Eclipse 400, or JEOL GX 400 spectrometer. 31P{1H},
13C{1H}, and 1H NMR spectra were recorded at the ambient
temperature of the probe at 300, 100, and 121 MHz, respectively,
using deuterated solvent to provide the field/frequency lock.
1,3,5,7-Tetramethyl-4,6,8-trioxa-2-phosphaadamantane (CgPH). A
three-necked 1 L flask was equipped with a large magnetic stirrer
bar, a thermometer, a gas inlet fitted to a mineral oil bubbler and
then a gas manifold to allow for N2/PH3 admission (fine gas bubbles
were obtained using a sintered-glass bulb attached to the bottom
of a standard glass inlet), a gas outlet fitted to a mineral oil bubbler
followed by a bleach trap,20 and then another mineral oil bubbler.
The flask was charged with acetylacetone (150 cm3, 1.46 mol) and
aqueous HCl (300 cm3, 5 M), and then N2 was passed through the
Conclusion
The large bulk, robustness, and unusual electronic properties
of CgPR have already been exploited in several applications in
homogeneous catalysis. The three general routes to the mono-
dentate cage tertiary phosphines CgPR described here should
make accessible a great variety of CgPR ligands and stimulate
further investigations of their chemistry. The routes described
have been applied to the synthesis of chelating diphosphines
containing CgP substituents, and this will be the subject of a
future publication.
Experimental Section
(15) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518.
(16) McDermott, J. X.; White, J. F.; Whitesides, G. M. J. Am. Chem.
Soc. 1976, 98, 6521.
Unless otherwise stated, all reactions were carried out under a
dry nitrogen atmosphere using standard Schlenk line techniques.
Dry N2-saturated solvents were collected from a Grubbs solvent
(17) Drew, D.; Doyle, J. R. Inorg. Synth. 1972, 13, 47.
(18) Doyle, R.; Slade, P. E.; Jonassen, H. B. Inorg. Synth. 1960, 6, 216–
219.
(14) (a) Roodt, A.; Otto, S.; Steyl, G. Coord. Chem. ReV. 2003, 245,
121. (b) Clarke, M. L.; Halliday, G. L.; Slawin, A. M. Z.; Woollins, J. D.
Dalton Trans. 2002, 1093.
(19) McCleverty, J. A.; Wilkinson, G. Inorg. Synth. 1990, 28, 84.
(20) Ellis, J. W.; Harrison, K. N.; Hoye, P. A. T.; Orpen, A. G.; Pringle,
P. G.; Smith, M. B. Inorg. Chem. 1992, 31, 3026.

3222 Organometallics, Vol. 27, No. 13, 2008
Downing et al.
solution for 18 h to ensure the elimination of oxygen. The reaction
vessel was cooled in an ice/water bath to 0 °C, and then gaseous
PH3 was passed through the solution for 7 h at such a rate that it
was absorbed by the reaction mixture (monitored by observation
of the oil bubblers). Caution! PH3 gas is highly toxic and an
explosion hazard. It should be handled with extreme care. Nitrogen
was again bubbled through the mixture for 16 h to ensure the
elimination of any PH3 before workup. A very sensitive test for
the presence of PH3 is to use filter paper which has been dipped in
a solution of AgNO3sit turns black in the presence of minute
quantities of PH3 gas. The white crystalline solid was then filtered
off in air, washed with water (3 × 200 cm3), and dried under
reduced pressure to give CgPH (78.5 g, 50% yield). Anal. Found
(calcd for C10H17O3P): C, 55.5 (55.6); H, 8.3 (7.9). 31P NMR
(CDCl3): δP -49.5 (d × mult J(PH) ) 190 Hz). 13C NMR (CDCl3):
δC 96.6 (s), 96.3 (s), 71.9 (d, J(PC) ) 18 Hz), 70.3 (s), 45.1 (s),
45.6 (d, J(PC) ) 14 Hz), 29.7 (d, J(PC) ) 23 Hz), 29.0 (d, J(PC)
) 12 Hz), 27.9 (s), 27.7 (s). 1H NMR (CDCl3, assignment by COSY
and spectral simulation): δH 3.08 (dm, 1H, J(PH) ) 190 Hz, J(HH)
) 1.6, 3.2, 0.6 Hz), 1.91 (ddd, 1H, CH2, J(PH) ) 2.6 Hz, J(HH)
) 12.8, 0.6 Hz), 1.81 (ddd, 1H, CH2, J(PH) ) 6.6 Hz, J(HH) )
1.6, 13.1 Hz) 1.79 (ddd, 1H, CH2, J(PH) ) 21.4 Hz, J(HH) ) 3.2,
13.1 Hz), 1.73 (d, 1H, CH2, J(HH) ) 12.8 Hz), 1.48 (d, 3H, CH3,
J(PH) ) 14 Hz), 1.46 (d, 3H, CH3, J(PH) ) 14 Hz), 1.39 (s, 3H,
CH3), 1.38 (s, 3H, CH3).
Hz), 25.7 (d, J(PC) ) 2.0 Hz), 25.5 (d, J(PC) ) 7.5 Hz). 1H NMR
(CDCl3): δH 4.40 (d, 1H, PH, 1J(PH) ) 180 Hz), 2.13 (m, 2H,
CH2), 1.82 (m, 2H, CH2), 1.47 (m, 12H, CH3), 1.08-0.18 (br, 3H,
BH3). 11B NMR (CDCl3): δB 45.6 (br).
CgPCl. To a solution of CgPH (4.32 g, 20.0 mmol) in CCl4 (50
cm3) cooled to between -5 and -10 °C was added N-chlorosuc-
cinimide (4.42 g, 33.0 mmol) in ca. 0.5 g portions over 15 min.
The reaction mixture was then cooled to -10 °C and the resulting
white precipitate was filtered off and washed with CCl4 (2 × 20
cm3). The solvent was then reduced to dryness to give CgPCl as a
yellow solid (4.96 g, 93%). Accurate mass spectrum: Mr ) 250.0516
(calcd for C10H16O3PCl 250.0526). 31P NMR (CDCl3): δP 53.6.13C
NMR (CDCl3): δC 96.6 (d, J(PC) ) 1.5 Hz), 95.8 (s), 74.8 (d,
J(PC) ) 23.83 Hz), 74.2 (d, J(PC) ) 39.21 Hz), 43.9 (d, J(PC) )
20.0 Hz, CH2), 34.1 (s, CH2), 27.7 (s, CH3), 27.3 (d, J(PC) ) 1.5
Hz, CH3), 26.9 (d, J(PC) ) 23.8 Hz, CH3), 26.0 (d, J(PC) ) 12.3
Hz, CH3). 1H NMR (CDCl3): δH 2.25 (d, 1H, CH2, J(HH) ) 13.5
Hz), 1.99 (d, 1H, CH2, J(PH) ) 5.3 Hz), 1.93 (s, 1H, CH2), 1.55
(dd, 1H, CH2, J(HH) ) 13.5 Hz, J(PH) ) 5.0 Hz), 1.41 (d, 3H,
CH3, J(PH) ) 1.3 Hz), 1.39 (s, 3H, CH3), 1.36 (s, 6H, CH3).
CgPBr. This could be made by a procedure similar to that for
CgPCl, using N-bromosuccinimide. However, a more convenient
procedure is as follows. A solution of Br2 (1.83 mmol, 8.4 cm-3
,
0.218 M in CH2Cl2) was added dropwise over 10 min to a cooled
(0 °C) solution of CgPH (0.368 g, 1.7 mmol) in CH2Cl2 (10 cm-3).
After 1 h the solvent was removed to give a yellow-orange solid.
Toluene (10 cm-3) was added to the solid and the suspension
filtered. Removal of the toluene then yielded a white powder of
CgPBr (0.393 g, 78%). Anal. Found (calcd for C10H16BrO3P): C,
40.7 (40.7); H, 5.7 (5.5). EI mass spectrum: m/z 294, 296 (M+).
31P NMR (CDCl3): δP 54.9. 13C NMR (CDCl3): δC 96.8 (d, J(PC)
) 1.5 Hz), 95.9 (s), 74.0 (d, J(PC) ) 26.9 Hz), 73.0 (d, J(PC) )
41.5 Hz), 43.8 (d, J(PC) ) 19.2 Hz, CH2), 34.8 (s, CH2), 27.8 (s,
CH3), 27.3 (d, J(PC) ) 2.4 Hz, CH3), 27.06 (d, J(PC) ) 23.1 Hz,
CH3), 27.03 (d, J(PC) ) 12.5 Hz, CH3). 1H NMR (CDCl3): δH
2.41 (d, 1H, CH2, J(HH) ) 13.5 Hz), 2.07 (s, 1H, CH2), 2.00 (d,
1H, CH2, J(PH) ) 7.3 Hz), 1.62 (dd, 1H, CH2, J(HH) ) 13.5 Hz,
J(PH) ) 4.6 Hz), 1.43 (d, 3H, CH3, J(PH) ) 2.7 Hz), 1.40 (s, 3H,
CH3), 1.37 (s, 3H, CH3), 1.36 (s, 3H, CH3).
1,3,5,7-Tetraethyl-4,6,8-trioxa-2-phosphaadamantane (EtCg-
PH). A three-necked 250 cm3 flask was equipped as in the
preparation of CgPH above. The flask was charged with 3,5-
heptanedione (10 cm3, 0.073 mol) and aqueous HCl (100 cm3, 8
M), and then N2 was passed through the solution for 18 h to ensure
the elimination of oxygen. The reaction vessel was cooled in a dry
ice/ethylene glycol bath to -12 °C, and then gaseous PH3 was then
passed through the solution for 7 h at such a rate that it was absorbed
by the reaction mixture (monitored by observation of the oil
bubblers). Caution! PH3 gas is highly toxic and an explosion hazard.
It should be handled with extreme care. Nitrogen was again bubbled
through the mixture for 16 h to ensure the elimination of any PH3
before workup. A very sensitive test for the presence of PH3 is to
use filter paper which has been dipped in a solution of AgNO3sit
turns black in the presence of minute quantities of PH3 gas. The
solution was then cooled in a salt/ice bath and neutralized by the
slow addition of N2-saturated NaOH solution (160 cm3, 5 M) until
pH 7. N2-saturated diethyl ether (200 cm3) was then added and
stirred. The ethereal layer was separated and the aqueous layer
washed with diethyl ether (3 × 20 cm3). The organic extracts were
combined and dried over MgSO4, and then the solvent was removed
under reduced pressure to give EtCgPH as a viscous air-sensitive
oil (7.42 g, 75% yield). Anal. Found (calcd for C14H25O3P): C,
61.31 (61.73); H, 8.90 (9.26). FAB mass spectrum: m/z 272 (M+).
31P NMR (CDCl3): δP -57.9 (d × mult J(PH) ) 190 Hz). 13C
NMR (CDCl3): δC 97.4 (s), 97.1 (s), 74.8 (d, J(PC) ) 22 Hz),
73.5 (d, J(PC) ) 8 Hz), 41.6 (d, J(PC) ) 13 Hz), 39.0 (d, J(PC)
) 14 Hz), 35.7 (s), 35.5 (s), 35.2 (s), 35.0 (s), 33.7 (s), 33.3(s). 1H
NMR (CDCl3): δH 1.40-2.20 (m, 18H), 0.80-1.34 (m, 12H).
CgPH(BH3). A solution of BH3 · THF (37.3 cm3, 1 M in THF,
37.3 mmol) was added slowly over 30 min to a stirred, ice-cold
solution of CgPH (8.00 g, 37.3 mmol) in THF (20 cm3). The
reaction mixture was then warmed to room temperature and the
solvent removed under reduced pressure to give a white powder.
The solid was dissolved in hot THF (6 cm3) and the resulting
solution cooled slowly to room temperature and then put in the
freezer (-10 °C) to give the crystalline white solid CgPH(BH3)
(8.223 g, 96%). Anal. Found (calcd for for C10H20BO3P): C, 52.2
(52.2); H, 8.8 (8.8). EI mass spectrum: m/z 230 (M+). 31P NMR
i
CgPiPr. Method a via PH2 Pr. Acetylacetone (7.1 cm3, 69.1
i
mmol) was added to a mixture of PH2 Pr (1.0 cm3, 11.5 mmol)
and 10 M aqueous HCl (10 cm3) and the resulting solution stirred
at room temperature. After 6 days, a white precipitate had formed,
and after a further 5 days, the precipitate was filtered off washed
with water (3 × 20 cm3). The filtrate then contained more
precipitated product, and this too was filtered off and washed with
water (2 × 20 cm3). The combined yield of CgPiPr was 1.19 g
(41%). Anal. Found (calcd for C13H23O3P + 0.25H2O): C, 59.4
(59.5); H, 9.2 (9.0). EI mass spectrum: m/z 258 (M+). 31P NMR
(CDCl3): δP -7.4. 13C NMR (CDCl3): δC 96.3 (s), 95.8 (s), 73.4
(d, J(PC) ) 25 Hz), 72.8 (d, J(PC) ) 13 Hz), 45.7 (d, J(PC) ) 15
Hz), 38.2 (s), 29.9 (d, J(PC) ) 21 Hz), 28.6 (d, J(PC) ) 12 Hz),
28.3 (s), 28.0 (s), 23.8 (d, J(PC) ) 24 Hz), 21.3 (d, J(PC) ) 21
Hz), 21.1 (d, J(PC) ) 9 Hz). 1H NMR (CDCl3): δH 1.90-2.08 (m,
2H), 1.64-1.86 (m, 3H), 1.45 (s, 3H), 1.40 (s, 3H), 1.39 (s, 3H),
2
1.37 (s, 3H), 1.24 (dd, 3H, J(PH) ) 17.1 Hz, 3J(HH) ) 7.6 Hz),
2
3
1.09 (dd, 3H, J(PH) ) 11.3 Hz, J(HH) ) 7.6 Hz).
Method b via CgPH(BH3). A solution of BuLi (0.5 cm3, 1.6
M in hexane, 0.80 mmol) was added dropwise over 5 min to a
solution of CgPH(BH3) (185 mg, 0.80 mmol) in THF (10 cm2) at
-78 °C. The resulting bright yellow solution was then warmed to
room temperature and stirred for a further 15 min. The solution
was then recooled to -78 °C, and a solution of 2-bromopropane
(0.076 cm3, 0.81 mmol) in THF (10 cm3) was added dropwise over
15 min. The mixture was then warmed to room temperature and
stirred for a further 24 h. The 31P NMR spectrum of the solution
showed a broad signal at δP 23.5 consistent with the formation of
1
(CDCl3): δP 1.5 (br q, J(PB) ) 39 Hz). 13C NMR (CDCl3): δC
96.8 (s), 96.6 (s), 70.9 (d, J(PC) ) 30 Hz), 68.7 (d, J(PC) ) 37.5
Hz), 44.2 (s), 38.3 (d, J(PC) ) 15.0 Hz), 27.7 (d, J(PC) ) 22.5

Alkyl Phosphatrioxaadamantane Ligands
Organometallics, Vol. 27, No. 13, 2008 3223
CgPiPr(BH3). An excess of distilled Et2NH (2.0 cm3, 19 mmol)
was added, and the solution was stirred for a further 24 h. The 31
P
NMR spectrum of this solution showed the borane adduct had been
completely converted to CgPiPr. The volatiles were removed under
reduced pressure to leave a white solid. Pentane (40 cm3) was
added, and the colorless solution was filtered free of LiBr and
Et2NHBH3 by cannula. The solvent was then removed under
reduced pressure to give a white solid, which was recrystallized
from hot methanol (10 cm3) to give white solid CgPiPr (147 mg,
71% yield).
i
Method c via CgPBr. PrMgCl (7.52 mmol, 3.76 cm3, 2 M in
THF) was added dropwise over 15 min to a solution of CgPBr
(0.40 g, 1.36 mmol) in toluene (10 cm3) at room temperature. The
solution was then stirred for 1 h, quenched with water (5 cm3),
and extracted using hexane (3 × 10 cm3). Removal of the solvent
under reduced pressure gave white solid CgPiPr (0.23 g, 66% yield).
CgPBz was made in 62% yield by method b. Anal Found (calcd
for for C17H23O3P): C, 66.7 (66.5); H, 7.5 (7.1). EI mass spectrum:
m/z 306 (M+). 31P NMR (CDCl3): δP -24.4. 13C NMR (CDCl3):
δC 143.5 (d, 1J(PC) ) 10.5 Hz), 140.3 (s), 130.2 (d, J(PC) ) 7.0
Hz), 127.8 (s), 127.2 (d, J(PC) ) 2.0 Hz), 96.6 (s), 95.4 (s), 76.1
(d, J(PC) ) 26 Hz), 72.7 (d, J(PC) ) 5 Hz), 44.7 (d, J(PC) ) 14
Hz), 37.4 (s), 27.8 (d, J(PC) ) 11 Hz), 27.3 (s), 26.9 (s), 26.7 (s),
1
25.6 (s). H NMR (CDCl3): δH 7.75-6.95 (m, 5H, Ph), 3.11 (dd,
2
2
2H, CH2Ph, J(PH) ) 16 Hz, J(HH) ) 4 Hz), 2.59 (2H, CH2,
2J(PH) ) 16 Hz, 2J(HH) ) 4 Hz), 1.98-1.05 (m, 16H, 2CH2 and
4CH3).
CgPC20H41 is a white solid which was made in 82% yield by
method b. Anal. Found (calcd for C30H57O3P), C, 72.7 (72.5); H,
11.6 (11.5). EI mass spectrum: m/z 497 (M+ + 1). 31P NMR
(CDCl3): δP -28.1. 13C NMR (CDCl3): δC 96.7 (s), 95.8 (s), 76.7
(d, J(PC) ) 1.5 Hz), 72.3 (d, J(PC) ) 19 Hz), 44.8 (d, J(PC) ) 22
Hz), 37.3 (d, J(PC) ) 4 Hz), 30-23 (alkyl C). 1H NMR (CDCl3):
δH 2.81-0.78 (m).
CgPMe is an off-white solid which was made in 75% yield by
method c. Accurate mass spectrum: Mr ) 230.1070 (calcd for
C11H19O3P, 230.1072). 31P NMR (CDCl3): δP -41.5. 13C NMR
(CDCl3): δC 96.8 (s), 95.8 (s), 72.2 (d, J(PC) ) 6 Hz), 71.5 (d,
J(PC) ) 21 Hz), 44.4 (d, J(PC) ) 16 Hz, CH2), 36.2 (d, J(PC) )
1.5 Hz, CH2), 28.0 (d, J(PC) ) 13 Hz, CH3), 27.5 (d, J(PC) )
23.0 Hz, CH3), 26.2 (d, J(PC) ) 13.0 Hz, CH3) 4.0 (d, J(PC) ) 25
Hz, CH3), 1H NMR (CDCl3): δH 1.96-1.81 (m, 2H), 1.75 (d, 1H,
J(HH) ) 13.2 Hz), 1.53 (dd, 1H, J(HH) ) 13.2, 4.0 Hz), 1.35 (s,
6H), 1.28 (d, 3H, J(PH) ) 12.9 Hz), 1.25 (d, 3H, J(PH) ) 12.5
Hz), 0.92 (d, 3H, J(PH) ) 3.3 Hz).
cis-[PtCl2(CgPH)2] (1). A solution of CgPH (0.800 g, 3.70
mmol) in CH2Cl2 (10 cm3) was added to a solution of [PtCl2(cod)]
(0.690 g, 1.90 mmol) in CH2Cl2 (10 cm3) and the mixture stirred
for 4 h. The white solid product (0.820 g, 64% yield) that had
precipitated was filtered off and washed with pentane. Anal. Found
(calcd for C20H34Cl2O6P2Pt): C, 34.4 (34.4); H, 5.2 (4.9). 31P NMR
(CDCl3): δP 1.2 (1J(PtP) ) 3292 Hz) and 1.6 (1J(PtP) ) 3299 Hz),
|1J(PH) + 3J(PH)| ) 405 Hz. Complex 1 was very sparingly soluble,
and no 13C NMR spectrum was obtained. Crystals of 1 grew when
a CH2Cl2 solution of CgPH was allowed to diffuse into a CH2Cl2
solution of [PtCl2(cod)].
cis-[PdCl2(CgPH)2] (2). A solution of CgPH (1.00 g, 4.60 mmol)
in CH2Cl2 (15 cm3) was added to a solution of [PdCl2(cod)] (0.660
g, 2.30 mmol) in CH2Cl2 (15 cm3) and the mixture stirred for 10
min. The cloudy solution was concentrated to 5 cm3, and then
pentane (15 cm3) was added to precipitate the yellow solid product
(1.07 g, 75% yield), which was filtered off and washed with pentane.
Anal. Found (calcd for C20H34Cl2O6P2Pd): C, 39.4 (39.4); H, 6.0
(5.6). 31P NMR (CDCl3): δP 3.0, 2.7 (d, |1J(PH) + 3J(PH)| ) 368
Hz). 13C NMR (CDCl3): δC 96.8 (s), 96.7 (s), 73.6 (t, |1J(PC) +
3J(PC)| ) 19.8 Hz), 73.4 (t, |1J(PC) + 3J(PC)| ) 13.8 Hz), 72.2 (t,
3
|1J(PC) + J(PC)| ) 26.0 Hz), 46.65 (s), 46.60 (s), 39.9 (s), 39.7

3224 Organometallics, Vol. 27, No. 13, 2008
Downing et al.
(s), 29.0 (s), 28.8 (s), 27.7 (s), 27.6 (s), 27.4 (s), 27.3 (s). 1H NMR
(CDCl3): δH 4.28 (m, 2H, PH, |1J(PH) + 3J(PH)| ) 363 Hz), 2.80
(m, 4H, CH2), 1.97 (m, 4H, CH2), 1.68 (m, 12H, CH3), 1.43 (m,
6H, CH3), 1.39 (m, 6H, CH3).
31P NMR (CD2Cl2): δP 14.4 (J(RhP) ) 117 Hz). IR (CH2Cl2):
ν(CO) 1989 cm-1. The analogous complexes trans-[RhCl(CO)(Cg-
PX)2] (5a-c,e) were made in situ and characterized in solution by
IR (see the Results and Discussion) and 31P NMR (CD2Cl2): 5a,
δP 33.3 and 33.1 (J(RhP) ) 130 and 128 Hz); 5b, δP 15.1 and
14.6 (J(RhP) ) 128 and 129 Hz); 5c, δP 27.3 (J(RhP) ) 134 Hz);
5e (at -80 °C), δP 97.7 and 99.0 (J(RhP) ) 145 and 145 Hz).
X-ray Experiments. X-ray diffraction experiments on 3b and
4c were carried out at 100 K on a Bruker SMART APEX
diffractometer, experiments on [CgP(CH2Ph)2]Br, CgPH, and CgPCl
were carried out at 173 K on a Bruker SMART diffractometer,
using Mo KR X-radiation (λ ) 0.710 73 Å), the experiment on 1
was carried out at 100 K on an Oxford Diffraction Gemini R Ultra
diffractometer, using Mo KR X-radiation (λ ) 0.710 73 Å), and
the experiment on CgP(n-C20H41) was carried out at 100 K on a
Bruker PROTEUM diffractometer using Cu KR X-radiation (λ )
1.541 78 Å); all data collections were performed using a single
crystal coated in paraffin oil mounted on a glass fiber. Intensities
were integrated from several series of θ scan exposures. Absorption
corrections were based on equivalent reflections,21,22 and structures
trans-[PdCl2(CgPiPr)2] (3a). A solution of CgPiPr (44 mg, 0.17
mmol) in CH2Cl2 (2 cm3) was added to
a solution of
[PdCl2(NCPh)2] (30 mg, 0.078 mmol) in CH2Cl2 (1 cm3). The pale
yellow solution was stirred for 30 min at room temperature, after
which time a yellow precipitate had formed, which was filtered
off, washed with CH2Cl2 (2 cm3), and dried. The yellow solid
product was sparingly soluble (33 mg, 62% yield). Anal. Found
(calcd for C26H46Cl2O6P2Pd): C, 44.8 (45.0); H, 6.8 (6.7). FAB mass
spectrum: m/z 658 (M+ - Cl). 31P NMR (CDCl3): δP 13.1, 13.3.
Complex 3b as an orange solid was made similarly from CgPCy
in 72% yield. Satisfactory elemental analyses were not obtained,
but a crystal structure was determined (see the Results and
Discussion). FAB mass spectrum: m/z 739 (M+ - Cl). 31P NMR
(CDCl3): δP 9.2, 9.4.
trans-[PtCl2(CgPiPr)2] (4a). A solution of CgPiPr (44 mg, 0.17
mmol) in CH2Cl2 (2 cm3) was added to a solution of [PtCl2(cod)]
(30 mg, 0.080 mmol) in CH2Cl2 (1 cm3). The pale yellow solution
was stirred for 2 h at room temperature, and then all the volatiles
were removed under reduced pressure. The yellow residue was
recrystallized from diethyl ether/pentane to give the off-white solid
product (32 mg, 51% yield). Anal. Found (calcd for 4a · 2CH2Cl2,
C28H50Cl6O6P2Pt): C, 35.0 (35.3); H, 5.0 (5.3). FAB mass spectrum:
m/z 783 (M+). 31P NMR (CDCl3): δP 3.08 (J(PtP) ) 2600 Hz),
3.16 (J(PtP) ) 2610 Hz). 195Pt NMR (CDCl3): δPt 868 (J(PtP) )
2600 Hz), 871 (J(PtP) ) 2610 Hz). Complex 4b was made similarly
from CgPCy in 68% yield. FAB mass spectrum: m/z 862 (M+).
31P NMR (CDCl3): δP -0.0 (J(PtP) ) 2599 Hz), 0.1 (J(PtP) )
2599 Hz).
2
were refined against all Fo data with hydrogen atoms riding in
calculated positions using SHELXTL.23 Crystal and refinement data
are given in Table 1. For 4c, the residual electron density different
maps showed some extra electron density in regions between the
complex molecules which could not be identified. The data were
refined using SQUEEZE,24 which resulted in an improvement in
the R factor of approximately 0.03. The SQUEEZE algorithm
calculated an extra 154 electrons in a volume of 383 Å3. This
approximates to between three and four solvent molecules of
CH2Cl2 per molecule of complex.
Acknowledgment. We thank Shell for studentships to J.F.
and R.I.P. and the EPSRC for studentships to J.H.D., K.H.,
M.F.H., and J.H. We thank Oxford Diffraction for the loan
of a diffractometer and Johnson-Matthey for a loan of pre-
cious metal compounds.
trans-[PtCl2(CgPC20H41)2] (4c). A solution of CgPC20H41 (380
mg, 0.76 mmol) in CH2Cl2 (5 cm3) was added to a solution of
[PtCl2(cod)] (130 mg, 0.35 mmol) in CH2Cl2 (5 cm3). The pale
yellow solution was stirred for 1 h at room temperature, and then
the volatiles were removed under reduced pressure. The yellow
residue was triturated with diethyl ether (50 cm3) to give the pale
yellow solid, which was filtered off, washed with diethyl ether (20
cm3), and dried to give 4c (430 mg, 98% yield). An analytically
pure sample of 4c was crystallized by slow evaporation of a CH2Cl2
solution. Anal. Found (calcd fofor C60H114Cl2O6P2Pt): C, 56.9
(57.2); H, 8.8 (9.1). FAB mass spectrum: m/z 1188 (M+ - 2Cl).
31P NMR (CDCl3): δP 1.22 (J(PtP) ) 2594 Hz), 1.41 (J(PtP) )
Supporting Information Available: CIF files giving X-ray
crystal data, atomic coordinates, bond lengths and angles, and
thermal displacement parameters for the compounds CgPH, CgPCl,
CgP(C20H41), [CgPBz2]Br, 1, 3b, and 4c. This material is available
free of charge via the Internet at http://pubs.acs.org.
OM800141Y
1
2602 Hz). H NMR (CDCl3): δH 2.13-0.75.
(21) (a) SAINT Integration Software; Siemens Analytical X-ray Insru-
ments Inc., Madison, WI, 1994. (b) CrysAlis RED; Oxford Diffraction Ltd.,
Oxford, U.K., 2007.
(22) Sheldrick, G. M. SADABS V2.10; University of Go¨ttingen,
Go¨ttingen, Germany, 2003.
(23) SHELXTL Program System Version 5.1; Bruker Analytical X-ray
Instruments, Inc., Madison, WI, 1998.
(24) Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;
Utrecht University, Utrecht, The Netherlands., 2007.
trans-[RhCl(CO)(CgPH)2] (5d). A solution of CgPH (144 mg,
0.67 mmol) in CH2Cl2 (5 cm3) was added to a solution of
[Rh2Cl2(CO)4] (65 mg, 0.17 mmol) in CH2Cl2 (10 cm3). The pale
yellow solution was stirred for 10 min at room temperature, and
then the solution was reduced to ca. 2 cm3. Addition of pentane
(10 cm3) precipitated the yellow solid product (140 mg, 70%). Anal.
Found (calcd for C21H34ClO7P2Rh): C, 42.3 (42.1); H, 6.0 (5.7).