Synthesis of a chelating hexadentate ligand with a P3N 3 donor set. Crystal and molecular structure of [OC-6-22]-[Co{(R P*,RP*,RP*)-CH 3C(CH2PPhC6H4NH2

Article abstract of DOI:10.1039/b607847h

The first structurally authenticated example of a hexadentate chelating tertiary phosphine in which all six donors are bound to a single metal centre is described. The multidentate ligand (R_P*,R_P*, R_P*)- and (R_P

Full text of DOI:10.1039/b607847h

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Synthesis of a chelating hexadentate ligand with a P3N3 donor set. Crystal
and molecular structure of [OC-6-22]-[Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}](PF6)3
Justine Bennett,a Roy J. Doyle,a Geoffrey Salem*a and Anthony C. Willisb
Received 5th June 2006, Accepted 27th July 2006
First published as an Advance Article on the web 8th August 2006
DOI: 10.1039/b607847h
The first structurally authenticated example of a hexadentate chelating tertiary phosphine in which all
six donors are bound to a single metal centre is described. The multidentate ligand (RP*,RP*,RP*)- and
(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3 has been prepared in 80% yield via the reaction of five
equivalents of sodium (2-aminophenyl)phenylphosphide (generated in situ from
(2-aminophenyl)phenylphosphine and sodium in thf) with 1,1,1-tri(bromomethyl)ethane in thf. The
diastereomeric mixture has been complexed to cobalt(III) and the resulting pair of complexes, viz.
[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3 and [CoCl{(RP*,RP*,SP*)-CH3C(CH2-
PPhC6H4NH2-2)3}]Cl2, separated by ion exchange chromatography. The structure of the former (as the
corresponding hexafluorophosphate salt) has been confirmed by X-ray crystallography and clearly
shows all six donors of the P3N3 ligand coordinated to a single cobalt(III) centre. The related
hexadentate ligand with internal N donors and terminal diphenylphosphino groups, viz.
CH3C(CH2NHC6H4PPh2-2)3, has also been synthesised, albeit in low yield, via the reaction of
[Li(tmeda)][2-NHC6H4PPh2] (generated in situ from (2-aminophenyl)diphenylphosphine,
n-butyllithium and tmeda in diethyl ether) with 1,1,1-tri(iodomethyl)ethane in thf. No formation of a
P3N3 ligand has been observed when either Na[2-PPhC6H4NH2] or [Li(tmeda)][2-NHC6H4PPh2] is
reacted with the related tripodal substrate 1,1,1-tris(tolyl-4-sulfonyloxymethyl)ethane in thf. Rather the
P-methyloxetane ( )-[3-{(2-aminophenyl)phenylphosphinomethyl}]-3-methyloxetane and the
sulfonamide 2-(4-CH3C6H4SO2)NHC6H4PPh2 and the corresponding N-methyloxetane
[3-{(2-diphenylphosphinophenyl)aminomethyl}]-3-methyloxetane have been isolated from the
respective reactions. The structure of the sulfonamide has been confirmed by an X-ray analysis of the
platinum(II) complex trans-[PtCl(CH3){2-PPh2C6H4NH(SO2C6H4CH3-4)}2].
N,N-dimethylbenzylamine or (S)-dimethyl(1-phenylethyl)amine,
Introduction
respectively.4 Separation of (RP*,RP*)- and (RP*,SP*)-C3-NP2N
Tertiary phosphine (2-aminophenyl)diphenylphosphine, adpp,1
is a versatile hybrid ligand that can be used to prepare a
range of related bidentate PN and multidentate P2N2 ligands
via derivatisation of the amino or diphenylphosphino groups.
Reductive cleavage of a phenyl moiety from adpp was readily
achieved with three equivalents of lithium in thf to give secondary
phosphine ( )-(2-aminophenyl)phenylphosphine, ( )-app, upon
hydrolysis.2,3 The latter was readily metallated with sodium
in thf and the resulting metal phosphide alkylated with, for
example, CH3I or Br(CH2)nBr (where n = 3–6) to give the biden-
tate PN ligand ( )-(2-aminophenyl)methylphenylphosphine, ( )-
ampp,2 or the linear quadridentate ligands (RP*,RP*)- and
(RP*,SP*)-(CH2)n(PPhC6H4NH2-2)2, (RP*,RP*)- and (RP*,SP*)-
Cn-NP2N.3,4 Separation of the racemic and meso diastereomers
of the linear quadridentate NP2N ligands and the resolu-
tion of (RP*,RP*)-C3-NP2N was achieved via separation by
fractional crystallisation of a pair of bis[palladium(II)] com-
plexes containing the respective ligand and orthometallated
has also been demonstrated by complexation to platinum(II).3
Reductive cleavage of a phenyl moiety from ( )-ampp was
similarly achieved using the above conditions and the secondary
phosphine ( )-(2-aminophenyl)methylphosphine, ( )-amp, iso-
lated upon hydrolysis.5 Metallation of the latter with sodium in
thf followed by alkylation of the resulting metal phosphide with
1,2-C6H4Cl2 gave the 2-chlorophenyl substituted PN ligand ( )-(2-
aminophenyl)(2-chlorophenyl)methylphosphine, ( )-acmp. Both
( )-ampp and ( )-acmp were resolved by the method of metal
resolution and the antipodes of the latter further reacted with
sodium (2-dimethylarsinophenyl)methylarsenide in thf to give
optically active multidentate As2NP and As4P ligands.2,5
Derivatisation of the amino group of adpp has been achieved
by complexation to nickel(II) and deprotonation with K2CO3, to
give the complex cis-[Ni(2-HNC6H4PPh2)2], followed by reaction
with one-half equivalent of 1,3-bis(tolyl-4-sulfonyloxy)propane
or 1,2-bis(tolyl-4-sulfonyloxy)ethane, respectively, in toluene to
give the linear quadridentate PN2P ligands (CH2)n(NHC6H4PPh2-
2)2 (where n = 2 or 3) upon decomplexation with aqueous
NaCN.6,7 Higher homologues could not be prepared by this route,
however, the analogous PN2P ligands (CH2)n(NHC6H4PPh2-2)2
(where n = 4 or 5) were successfully prepared by the Schiff
aChemistry Department, The Faculties, Australian National University,
Canberra, A. C. T., 0200, Australia. E-mail: Geoff.Salem@anu.edu.au
bResearch School of Chemistry, Australian National University, Canberra,
A. C. T., 0200, Australia
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base condensation of adpp with the appropriate acid chloride in
anhydrous thf in the presence of pyridine followed by reduction
with LiAlH4.8 The latter approach was also used to prepare related
linear quadridentate PN2P ligands containing a variety of linkages
between the N atoms by coupling the nitrogen donors of adpp
with substrates such as 1,1ꢀ-binaphthyl-2,2ꢀ-biscarbaldehyde and
trimethyl orthoformate.9 Both of these approaches have been used
to convert (RP*,SP*)-C3-NP2N to macrocyclic P2N2 ligands.10
In this work derivatisation of both the amino and diphenylphos-
phino groups of adpp has been investigated as a means of provid-
ing a viable synthetic route to hexadentate P3N3 ligands of the
type CH3C(CH2NHC6H4PPh2-2)3 and CH3C(CH2PPhC6H4NH2-
2)3, respectively. The latter exists as a 1 : 3 mixture of (RP*,RP*,RP*)
and (RP*,RP*,SP*) diastereomers (see Fig. 1), coordination of the
(RP*,RP*,RP*) form of the ligand to cobalt(III) providing the first
example of a hexadentate chelating tertiary phosphine in which all
six donors are bound to a single metal centre. The (RP*,RP*,SP*)
diastereomer is precluded from forming a similar complex as all
three stereogenic phosphorus centres need to have the same relative
configuration in order for the six donors to be able to bind to
the same metal ion. The presence of six phenyl groups on one
face of an octahedron also precludes CH3C(CH2NHC6H4PPh2-2)3
from forming a similar complex, however, it was anticipated that
derivatisation of the terminal diphenylphosphino groups, using a
similar approach to that used for the conversion of adpp to ( )-
app, could provide a route to a less sterically hindered analogue
capable of coordinating to a single metal ion.
Scheme 1 Reagents and conditions: (i) 3 Na, NH3(l); NH4Cl; (ii) Na,
thf; 0.2 CH3C(CH2Br)3, thf; (iii) n-BuLi, n-hexane, diethyl ether, tmeda;
0.33 CH3C(CH2I)3, thf.
from the reaction of n-butyllithium in n-hexane–diethyl ether
with adpp followed by the addition of tmeda. The corresponding
salt Na[PPhC6H4NH2-2] was generated in situ from ( )-app and
sodium in thf.2 The secondary phosphine ( )-app was prepared
from adpp using three equivalents of sodium in liquid ammonia
rather than the standard literature procedure of three equivalents
of lithium in thf, followed by hydrolysis. This proved to be a
more efficient route to ( )-app since it could be performed on
a large scale and routinely gave the product in high yield, in
contrast to the lithium reaction where the yield was much more
variable and the reaction times significantly longer. Interestingly,
whereas essentially completely chemoselective cleavage of a phenyl
from the analogous PN ligand ( )-ampp was found using three
equivalents of lithium in thf,5 little selectivity was observed using
three equivalents of sodium in liquid ammonia. Rather the crude
product consisted of a ca. 11 : 9 mixture of the secondary
phosphines ( )-amp and ( )-methylphenylphosphine,11 the latter
presumably being formed by cleavage of the 2-aminophenyl group.
This result suggests that the amino group of ( )-ampp does not
remain completely deprotonated under these reaction conditions.
The deprotonation of the amino group in adpp and ( )-ampp
on reaction with lithium in thf has previously been proposed to
account for the selective cleavage of a phenyl group.2,5
Fig. 1 Stereochemical representation of the tripodal hexadentate ligands
(RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3.
Results and discussion
Synthesis of P3N3 ligands
Synthesis of the hexadentate P3N3 ligands CH3C(CH2NHC6-
H4PPh2-2)3 and CH3C(CH2PPhC6H4NH2-2)3 was investi-
gated via the coupling of [Li(tmeda)][2-NHC6H4PPh2] and
Na[PPhC6H4NH2-2], respectively, with the tripodal substrates
CH3C(CH2X)3 (where X = Cl, Br, I or OTs) (see Scheme 1).
The salt [Li(tmeda)][2-NHC6H4PPh2] was isolated in 86% yield
The tripodal hexadentate P3N3 ligand (RP*,RP*,RP*)- and
(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3 was prepared in 80%
yield via the dropwise addition of a solution of CH3C(CH2Br)3 in
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˚
thf to a solution containing five equivalents of Na[PPhC6H4NH2-
2] in the same solvent at −78 ◦C, followed by allowing the
reaction to proceed at −20 ◦C for 20 days and ambient
temperature for a further 10 days. Significantly lower yields
of the P3N3 ligand were isolated when the reaction mixture
was not kept at −20 ◦C for several days, three rather than five
equivalents of Na[PPhC6H4NH2-2] were used, CH3C(CH2Cl)3
was used instead of CH3C(CH2Br)3, or when the addition
of the reagents was reversed i.e. addition of the Na[PPh-
C6H4NH2-2] solution to the tripodal substrate in thf. When
a stoichiometric amount of Na[PPhC6H4NH2-2] was used in
the coupling reaction with CH3C(CH2Br)3, (RP*,RP*,RP*)- and
(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3 was isolated by
column chromatography in only 28% yield. The chromatographic
separation yielded two other products, unreacted ( )-app
(35%) and the disubstituted product (RP*,RP*)- and (RP*,SP*)-
(CH3)2C(CH2PPhC6H4NH2-2)2 (18%). Formation of the latter
product can be rationalized in terms of substitution of two
of the bromo groups in CH3C(CH2Br)3 followed by reduction
Table 1 Selected non-hydrogen interatomic distances (A) and in-
teratomic angles (◦) for [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-
2)3}](PF6)3·C3H6O
Co–P(1)
Co–P(2)
Co–P(3)
2.2067(9)
2.1958(9)
2.1954(9)
Co–N(1)
Co–N(2)
Co–N(3)
2.024(3)
2.048(3)
2.032(2)
P(1)–Co–P(2)
P(2)–Co–P(3)
P(1)–Co–P(3)
P(1)–Co–N(1)
P(2)–Co–N(1)
P(3)–Co–N(1)
P(1)–Co–N(2)
P(2)–Co–N(2)
90.27(3)
89.81(3)
89.54(3)
85.48(8)
175.22(8)
92.34(8)
93.58(7)
85.64(8)
P(3)–Co–N(2)
P(1)–Co–N(3)
P(2)–Co–N(3)
P(3)–Co–N(3)
N(1)–Co–N(2)
N(1)–Co–N(3)
N(2)–Co–N(3)
174.49(8)
173.85(8)
93.32(8)
85.48(7)
92.4(1)
91.1(1)
91.7(1)
and [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)2,
by metathesis with aqueous NH4PF6 in methanol and suitable
crystals of the former complex for an X-ray analysis were obtained
by recrystallisation from isopropyl alcohol–acetone.
The complex [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-
2)3}](PF6)3·C3H6O is a racemic compound with both D and K
forms of the cation being present in the unit cell. Only the D form
of the cation is depicted in Fig. 2. Selected bond lengths and angles
are given in Table 1.
of the third bromomethyl group.
has previously been reported for the analogous reaction
between sodium (2-dimethylarsinophenyl)methylarsenide
A similar observation
and CH3C(CH2Cl)3.12 Here the disubstituted quadridentate
As4 ligands (RAs*,RAs*)-, (RAs*,RAs*,r*)- and (RAs*,SAs*,s*)-
CH3C(CH2Cl)(CH2AsMeC6H4AsMe2-2)2 were formed when
three rather than five equivalents of the sodium arsenide were
used in the reaction. Similarly, no evidence for the presence of
these disubstituted products was observed when five equivalents
of the sodium arsenide was used, the only products formed
were the expected hexa(tertiary arsine) (RAs*,RAs*,RAs*)- and
(RAs*,RAs*,SAs*)-CH3C(CH2AsMeC6H4AsMe2-2)3, and a cyclic
tetra(tertiary arsine) (RAs*,SAs*,RAs*)-5,6,7,8,9-pentahydro-6-
{[(2-dimethylarsinophenyl)methylarsino]methyl}-1,4,6-trimethyl-
benzo[b][1,4]diarsacycloheptane, consistent with complete
substitution of the three chloro groups in the substrate.
Evidence for the formation of the related tripodal hexadentate
P3N3 ligand CH3C(CH2NHC6H4PPh2-2)3 was found upon heating
a mixture of CH3C(CH2I)3 and three equivalents of [Li(tmeda)][2-
NHC6H4PPh2] in toluene under reflux for twelve days. The
HR-ESI mass spectrum of the crude reaction product exhib-
ited a molecular ion for CH3C(CH2NHC6H4PPh2-2)3 [calc. for
C59H53N3P3 (M − H)+: m/z 896.345239; found: 896.347243].
The reaction, however, had not proceeded to any great extent
with the crude reaction product being comprised largely of
unreacted starting materials. No reaction was observed between
[Li(tmeda)][2-NHC6H4PPh2] and the related tripodal substrates
CH3C(CH2X)3 (where X = Cl or Br) under similar conditions.
Fig.
2
Molecular structure of the cation [Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}]3+ (ellipsoids show 30% probability levels).
The structural data revealed a C3 symmetric cation in which all
six donor atoms of the P3N3 ligand were coordinated to a single
cobalt(III) centre in a facial arrangement and the three phosphorus
stereocentres had the same relative configuration. The complex
had a distorted octahedral geometry, as indicated by the trans P–
Co(1)–N bond angles which ranged between 173.85 and 175.22◦.
Isolation and crystal structure determination of
[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)3
Separation of the (RP*,RP*,RP*) and (RP*,RP*,SP*) forms of
CH3C(CH2PPhC6H4NH2-2)3 was achieved by complexation to
cobalt(III) followed by ion exchange chromatography to give two
complexes, viz. [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-
2)3}]Cl3 and [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-
2)3}]Cl2, in yields of 22 and 70%, respectively. Both complexes
were readily converted to the corresponding hexafluorophosphate
salts, [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)3
˚
The Co–P distances (2.21, 2.20, 2.20 A) and Co–N distances (2.02,
˚
˚
˚
2.05, 2.03 A) were within the ranges 2.17–2.25 A and 1.99–2.05 A,
respectively, observed for similar bonds in various mononuclear
cobalt(III) complexes.5,13
The structural integrity of the cation [Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}]3+ is retained in solution. The
4616 | Dalton Trans., 2006, 4614–4622
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1
31P{ H} NMR spectra of the complexes [Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}]X3 (where X = Cl or PF6) in
CD3OD revealed a single 31P resonance at d 54.6 and 55.2,
respectively, for the three equivalent phosphorus stereocentres,
consistent with the C3 symmetry of the cation.
The structure of [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6-
H4NH2-2)3}](PF6)2 has not been confirmed by X-ray crystallogra-
phy, however, the formulation given is consistent with analytical
data. The P3N3 ligand is believed to be coordinated in a pentaden-
tate fashion to the metal centre via three P and two N donor atoms
with a chloro ligand completing the octahedral arrangement about
1
the cobalt(III) centre. The 31P{ H} NMR spectrum of the complex
in CD3OD exhibited three broad singlet 31P resonances at d 18.2,
45.4 and 61.1, consistent with the expected C1 symmetry of the
cation and indicative of all three phosphorus donors of the P3N3
ligand being coordinated to the cobalt(III) centre.
Liberation of the P3N3 ligand from [Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}]Cl3 and [CoCl{(RP*,RP*,SP*)-
CH3C(CH2PPhC6H4NH2-2)3}]Cl2 was achieved by treatment
of the individual complexes with KCN in refluxing methanol-
benzene, however, the cyanolysis caused epimerisation at
phosphorus in each case leading to the isolation of a ca. 1 :
3 equilibrium mixture of (RP*,RP*,RP*)- and (RP*,RP*,SP*)-
Scheme 2 Reagents and conditions: (i) 5 [Li(tmeda)][2-NHC6H4PPh2]
(from n-BuLi, n-hexane, diethyl ether, tmeda and adpp), thf; (ii)
3 Na[PPhC6H4NH2-2] (from ( )-app and Na in thf), thf.
1
CH3C(CH2PPhC6H4NH2-2)3. The 31P{ H} NMR spectrum of the
liberated P3N3 ligand in each case was identical to that recorded for
the diastereomeric mixture of (RP*,RP*,RP*)- and (RP*,RP*,SP*)-
CH3C(CH2PPhC6H4NH2-2)3. The epimerisation of the
phosphorus stereocentres under these conditions was confirmed
by recomplexation of the cyanolysed products to cobalt(III)
and separation of the two complexes formed by fractional
crystallization from ethanol or ion-exchange chromatography. In
each case [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3
oxetane (67%) from the first reaction and the sulfonamide
2-(4-CH3C6H4SO2)NHC6H4PPh2 (73%), the N-methyloxetane [3-
{(2-diphenylphosphinophenyl)aminomethyl}]-3-methyloxetane
(52%) and recovered adpp from the second reaction. The corre-
sponding sulfonphosphide ( )-2-(4-CH3C6H4SO2)PPhC6H4NH2
was identified in the crude product from the first reaction
1
but could not be isolated in pure form. The 31P{ H} NMR
and
[CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl2
spectrum of the crude product in CDCl3 contained a singlet
resonance at d 36.8, within the d 33–45 range for 31P chemical
shifts observed for several other sulfonphosphides prepared from
lithium diphenylphosphide and the appropriate tosyl chloride,17
and the mass spectrum contained a peak at m/z 291 (M − SO2)
also indicative of the presence of the sulfonphosphide.
were again obtained in yields of ca. 23 and 72%, respectively,
indicating that the products of the cyanolysis reactions consisted
of a mixture of (RP*,RP*,SP*) and (RP*,RP*,RP*) diastereomers
close to the statistical ratio of 3 : 1.
This result was unexpected given that stereogenic tertiary
phosphine centres are usually configurationally stable under
these conditions. There have been several reports, however, of
the epimerisation of coordinated stereogenic arsenic centres in
cobalt(III) complexes containing multidentate arsine ligands.14,15
For example, Bosnich et al. reported the epimerisation of
the internal arsenic stereocentres in a cobalt(III) complex con-
taining the linear tetra(tertiary arsine), (RAs*,RAs*)-1,2-bis[(3-
dimethylarsinopropyl)phenylarsino]ethane, tetars.15 The inversion
was suggested to occur via a five-coordinate arsenic centre similar
to the mechanism proposed for the racemization of organoarson-
ium halides by Horner and Hofer.16
The structure of sulfonamide 2-(4-CH3C6H4SO2)NHC6H4PPh2
was confirmed by the preparation and subsequent crys-
tal structure determination of the complex trans-[PtClMe{2-
Ph2PC6H4NH(SO2C6H4CH3-4)}2]. The latter was prepared by the
reaction of two equivalents of the sulfonamide with [PtClMe(cod)]
in thf. The molecular structure of the complex is depicted in Fig. 3
and selected bond lengths and angles are given in Table 2. The
structural data clearly shows the presence of two trans disposed
sulfonamides bound to the platinum(II) centre as unidentate
ligands through the phosphorus donor atoms. The trans Pt–P
˚
bond lengths (2.310 A) are comparable to those observed in other
chloromethylplatinum(II) complexes containing trans disposed
phosphorus atoms, for example, trans-[PtClMe(PPh3)2] (2.295,
Reaction of Na[2-PPhC6H4NH2] and [Li(tmeda)][2-NHC6H4PPh2]
with 1,1,1-tris(tolyl-4-sulfonyloxymethyl)ethane, CH3C(CH2OTs)3
18
19
˚
˚
2.298 A) trans-[PtClMe(PMePh2)2] (2.291, 2.292 A), trans-
20
˚
No evidence for the formation of
a
hexadentate ligand
[PtClMe(PEt3)2] (2.296 A) and trans-[PtCl(CH2CN)(PPh3)2]
21
˚
was found when Na[2-PPhC6H4NH2] (three equivalents) or
[Li(tmeda)][2-NHC6H4PPh2] (five equivalents) were reacted with
CH3C(CH2OTs)3 in thf (Scheme 2). The key products after hydrol-
ysis were the starting material ( )-app and the P-methyloxetane
( )-[3-{(2-aminophenyl)phenylphosphinomethyl}]-3-methyl-
(2.308, 2.310 A). The bond lengths also fall within the range
˚
of 2.26–2.33 A reported for several square planar platinum(II)
complexes containing trans disposed phosphorus atoms.22 In
˚
addition, the C–S bond length of 1.762 A is similar to those
˚
observed (1.758–1.77 A) in several related compounds containing
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Fig.
3
Molecular structure of the complex [PtClMe{2-Ph2PC6H4-
NH(SO2C6H4CH3-4)}2] (ellipsoids show 30% probability levels).
˚
Table 2 Selected non-hydrogen interatomic distances (A) and interatomic
angles (◦) for [PtClMe{2-Ph2PC6H4NH(SO2C6H4CH3-4)}2]
Fig. 4 Proposed mechanism of formation of sulfonamide 2-(4-CH3-
C6H4SO2)NHC6H4PPh2 and N-methyloxetane [3-{(2-diphenylphosphino-
phenyl)aminomethyl}]-3-methyloxetane.
Pt–Cl
2.358(3)
2.3102(7)
2.3102(7)
Pt–C(26)
S(1)–N(1)
S(1)–C(7)
2.09(2)
1.648(3)
1.762(4)
Pt–P(1)
Pt–P(1)a
methyloxetane, and 3-(2-methoxyethoxymethyl)-3-methyloxetane
in the attempted preparation of hexaethers by the nucleophilic
substitution of CH3C(CH2OTs)3 with sodium alkoxides.26
Cl–Pt–P(1)
Cl–Pt–P(1)a
P(1)–Pt–P(1)a
91.70(15)
88.30(15)
180.0
Cl–Pt–C(26)
178.7(10)
87.6(8)
92.4(8)
P(1)–Pt–C(26)
C(26)–Pt–P(1)a
The formation of P-methyloxetane ( )-[3-{(2-aminophenyl)-
phenylphosphinomethyl}]-3-methyloxetane can be rationalized
in a similar manner. Thiophilic attack by Na[2-PPhC6H4NH2]
on the substrate CH3C(CH2OTs)3 would lead to the formation
of the sulfonphosphide ( )-2-(4-CH3C6H4SO2)PPhC6H4NH2 and
the same oxetane intermediate, 3-(tolyl-4-sulfonyloxy)methyl-3-
methyloxetane. Subsequent reaction of the latter with Na[2-
PPhC6H4NH2] presumably proceeds via substitution at carbon
with displacement of a tosylate to give the P-methyloxetane.
a Indicates an atom generated by the symmetry operation (1 − x, 1 − y,
1 −z).
an arylsulfonyl group.23 The N–S bond length of 1.648 A is within
˚
24
˚
the 1.62–1.69 A range expected for sulfonamides.
The formation of sulfonamide 2-(4-CH3C6H4SO2)NHC6H4-
PPh2 can be rationalized in terms of thiophilic attack by the
lithium reagent [Li(tmeda)][2-NHC6H4PPh2] on the substrate
CH3C(CH2OTs)3, the resulting alkoxide cyclising to give an oxe-
tane intermediate, 3-(tolyl-4-sulfonyloxy)methyl-3-methyloxetane
(see Fig. 4). The latter presumably reacts further with a
second equivalent of the lithium reagent to give the N-
methyloxetane [3-{(2-diphenylphosphinophenyl)aminomethyl}]-
3-methyloxetane, via substitution at carbon with displacement of
a tosylate. The reaction of organolithium compounds with aryl-
sulfonates has previously been reported to proceed by thiophilic
attack, rather than by substitution at carbon with displacement of
a tosylate.25,26 Moreover, steric crowding in the tripodal tritosylate
would presumably hinder access of the amide nucleophile to
the electrophilic carbon centre and prevent the substitution of
tosylate, resulting in nucleophilic attack at the more accessible
sulfur center. Steric crowding is greatly diminished in the proposed
oxetane intermediate and hence substitution of tosylate by the
lithium reagent presumably ensues to give the N-methyloxetane
product. A similar mechanism was proposed to account for the
formation of related compounds containing an oxetane ring, viz. 3-
methoxymethyl-3-methyloxetane, 3-(2-methoxyethoxymethyl)-3-
Conclusion
The first example of a structurally authenticated complex con-
taining a chelating hexadentate tertiary phosphine in which
all six donor atoms are bound to a single metal centre
has been described, viz. [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4-
NH2-2)3}](PF6)3. The P3N3 ligand was isolated in high yield
via the reaction of CH3C(CH2Br)3 with five equivalents of
Na[PPhC6H4NH2-2] in thf and the two diastereomeric forms
of the ligand separated by complexation to cobalt(III) fol-
lowed by column chromatography. Two complexes were iso-
lated, viz. [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3
and [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl2, and
subsequently converted to the corresponding hexafluorophos-
phate salts by metathesis with aqueous NH4PF6. Unfortunately
the diastereomerically pure ligand could not be removed from
the cobalt(III) centre in a stereospecific manner, a ca. 3 : 1
equilibrium mixture of the (RP*,RP*,SP*) and (RP*,RP*,RP*)
4618 | Dalton Trans., 2006, 4614–4622
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forms of the ligand, respectively, being isolated when either of
the two complexes was treated with KCN in refluxing methanol–
benzene. Current work is focussing on capping the three facial
nitrogen donors in [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-
2)3}](PF6)3 to give the first example of a P3N3 cryptand.
oil (54.8 g, 95%), bp 122 ◦C, 0.05 mm Hg. Analytical data for the
secondary phosphine was identical to that previously reported.2
(RP*,RP*,RP*)- and (RP*,RP*,SP*)-1,1,1-tris{(2-aminophenyl)-
phenylphosphinomethyl}ethane, (RP*,RP*,RP*)- and (RP*,RP*,
SP*)-CH3C(CH2PhPC6H4NH2-2)3.
(i) Via reaction of CH3C(CH2Br)3 with five equivalents of
sodium (2-aminophenyl)phenylphosphide. Secondary phosphine
( )-app (2.24 g, 0.0112 mol) was dissolved in thf (40 mL)
and sodium foil (0.256 g, 0.0112 mol) added piecewise to the
stirred solution. The reaction mixture was stirred overnight. The
resulting red metal phosphide solution was cooled to −78 ◦C
and CH3C(CH2Br)3 (0.689 g, 2.23 mmol) in thf (20 mL) added
dropwise to the stirred solution. The reaction mixture was allowed
to warm slowly to −20 ◦C and stirred at this temperature for a
further 20 d after which time the reaction mixture was allowed
to warm to room temperature and stirred at this temperature
for a further 10 d. Solid ammonium chloride (2 g) followed by
water (2 mL) were added. The solvent was removed under reduced
pressure and the residual oil dissolved in water (40 mL) and
dichloromethane (30 mL). The resulting phases were separated
and the aqueous phase extracted with further dichloromethane
(2 × 20 mL). The combined organic extracts were dried (MgSO4),
filtered and the solvent removed under reduced pressure. The
residual oil was distilled under reduced pressure to remove the
unre◦acted secondary phosphine ( )-app (0.92 g, 41%), bp 128–
Experimental
Procedures and materials
Reactions involving air-sensitive reagents were performed under
argon using Schlenk techniques. Solvents were dried and purified
by distillation under argon. NMR spectra were obtained using
a Varian Gemini 300 spectrometer operating at 300 MHz (1H),
121.5 MHz (31P{ H}) or 75 MHz (13C{ H}). Chemical shift values
(d) are reported in ppm referenced relative to tetramethylsilane for
1H, CDCl3 (77.0 ppm) or CD2Cl2 (53.8 ppm) as appropriate for
1
1
1
1
13C{ H} and external 85% aqueous H3PO4 for 31P{ H}. Melting
points were determined using a Leica Galen III melting point
apparatus and microscope fitted with a digital meter.
Elemental analyses were carried out by staff in the micro-
analytical laboratory at the Research School of Chemistry and
mass spectra for compounds with molecular weights over 400
obtained by staff at the Research School of Chemistry. ESI-
MS spectra were recorded on a FISONS VG QUATTRO II
mass spectrometer, operating at a cone voltage between 40 and
70 V, with positive ion detection. EI MS and HR-EI MS were
recorded on a VG autospec mass spectrometer, operating at 70
eV using positive ion detection. GC-EIMS spectra were recorded
on a Hewlett-Packard G1800A GCD mass spectrometer on a
HP-5 column [(crosslinked 5% phenyl methyl silicone) 30 m ×
0.25 mm × 0.25 mm film thickness], using helium as the carrier
gas◦(1 mL min−1), with a temperature gradient rising between 5–
15 C per minute as appropriate and operating between 100 and
330 ◦C using positive ion detection. Mass spectra are recorded in
mass/charge ratios (m/z).
1
1
130 C, 0.07 mmHg. H and 31P{ H} NMR spectra identical to
that of an authentic sample. The residue was triturated using
n-pentane (30 mL) to give (RP*,RP*,RP*)- and (RP*,RP*,SP*)-
CH3C(CH2PhPC6H4NH2-2)3 as a white microcrystalline solid.
The latter was filtered off, washed with n-pentane (2 × 3 mL)
and dried in vacuo (1.20 g, 80%). (Found: C, 69.81; H, 6.38; N,
5.71. Calc. for C41H42P3N3·2H2O: C, 69.77; H, 6.57; N, 5.95%). 1H
NMR (CD2Cl2): d 0.94 (s, 3 H, CH3); 2.34 (m, 6 H, PCH2); 4.20
1
(br s, 6 H, NH2); 6.52–7.47 (m, 27 H, aromatics). 31P{ H} NMR
1
(CD2Cl2): d −46.1 (s, 3 P); −46.4 (s, 3 P). 13C{ H} APT NMR
The compounds (2-aminophenyl)diphenylphosphine,1 [SP-
4-2]-chloro(cycloocta-1,5-diene)methylplatinum(II),27 1-chloro-
2,2-di(chloromethyl)propane, CH3C(CH2Cl)3,28 2,2-di(tolyl-
(CD2Cl2): d 28.9 (m, 1 C, CH3Cq); 38.9 (m, 1 C, CH3Cq); 42.0
(m, 3 C, PCH2Cq); 115.5–151.0 (m, 27 C, aromatics). LR-EI MS:
m/z 669 (M)+, 592 (M − Ph)+, 577 (M − C6H5CH3)+, 469 (M −
PhPC6H4NH2)+. HR-EI MS: Found for (M)+ 669.2604 (calc. for
C41H42N3P3: 669.2592).
4-sulfonyloxymethyl)-1-(tolyl-4-sulfonyloxy)propane,
CH3C-
(CH2OTs)3,29 1-bromo-2,2-di(bromomethyl)propane, CH3C(CH2-
Br)3,29 and 2,2-di(iodomethyl)-1-iodopropane, CH3C(CH2I)3,30
were prepared by literature procedures.
(ii) Via reaction of CH3C(CH2Br)3 with three equivalents of
sodium (2-aminophenyl)phenylphosphide. Secondary phosphine
( )-app (1.62 g, 8.06 mmol) was dissolved in thf (40 mL) and
sodium foil (0.185 g, 8.06 mmol) added piecewise to the stirred
solution. The reaction mixture was stirred at room temperature
for 48 h. The resulting red metal phosphide solution was cooled to
−78 ◦C and 1,1,1-tris(bromomethyl)ethane (0.829 g, 2.69 mmol) in
thf (20 mL) added dropwise to the stirred solution. The reaction
mixture was allowed to warm to room temperature and stirred
for 7 d. The reaction mixture was refluxed in thf for 4 d during
which time the colour discharged. Solid ammonium chloride
(2 g) followed by water (2 mL) were added. The solvent was
removed under reduced pressure and the residual oil dissolved
in water (40 mL) and dichloromethane (30 mL). The resulting
phases were separated and the aqueous phase extracted with
further dichloromethane (2 × 20 mL). The combined organic
extracts were dried (MgSO4), filtered and the solvent removed
under reduced pressure. The residual oil (1.42 g) was separated
Preparations
( )-(2-Aminophenyl)phenylphosphine,
( )-app. Ammonia
(1200 mL) was condensed onto adpp (80.0 g, 0.288 mol). Sodium
foil (19.9 g, 0.865 mol) was added piecewise to the stirred
solution. The reaction was allowed to stir in the cold for 2 h. Solid
ammonium chloride was added until the colour discharged and
the reaction mixture stirred overnight under nitrogen to allow
the ammonia to evaporate. Water (300 mL) and dichloromethane
(200 mL) were added to the residue. The resulting phases
were separated and the aqueous phase extracted further with
dichloromethane (2 × 200 mL). The combined organic extracts
were dried (MgSO4), filtered and the solvent removed via
distillation under nitrogen at 1 atm. Distillation of the crude oil
under reduced pressure gave the product as a colourless viscous
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Dalton Trans., 2006, 4614–4622 | 4619
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on a silica column (19 × 2.5 cm, silica gel 70–230 mesh, eluent
petroleum spirit (bp 40–60 ◦C)–dichloromethane, gradient 90 :
10 → 0 : 100) under nitrogen to give three fractions. Fraction 1:
( )-app (0.303 g, 35% based on starting ( )-app). 1H NMR and
NMR ((CD3)2CO): d 2.22 (s, 3 H, CH3); 3.35 (br s, 3 H, PCHH);
3.44 (br s, 3 H, PCHH); 6.03–7.98 (m, 33 H, aromatics & NH2).
1
31P{ H} NMR: d 55.2 (br s, 3 P).
[OC-6-23-(RP*,RP*,SP*)]-Chloro[1,1,1-tris{(2-aminophenyl)-
1
31P{ H} NMR spectra identical to an authentic sample. Fraction 2:
phenylphosphinomethyl}ethane-N2P3]cobalt(III) hexafluorophos-
(RP*,RP*)- and (RP*,SP*)-(CH3)2C(CH2PPhC6H4NH2-2)2 (0.23 g,
18%). 1H NMR (CD2Cl2): d 1.27 (s, 6 H, CH3C); 2.54 (m,
4 H, PCH2); 4.37 (br s, 4 H, NH2); 6.82–7.66 (m, 18 H,
phate,
[CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]-
(PF6)2. A solution of ammonium hexafluorophosphate (0.15 g,
0.92 mmol) in water (7 mL) was added slowly to a solution of
[CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl2 (0.08 g,
0.096 mmol) in methanol (4 mL) and left standing overnight.
The resulting orange precipitate was collected, washed with water
(3 × 5 mL) and dried in vacuo (0.06 g, 59%), mp 215–216 ◦C
(Found: C, 46.74; H, 4.24; N, 3.79; Co, 5.11; Cl, 2.91; F, 19.92.
Calc. for C41H42N3P5CoClF12·EtOH: C, 46.94; H, 4.40; N, 3.82;
1
aromatics). 31P{ H} NMR (CD2Cl2): d −44.5 (s, 2 P). LR-
EI MS: m/z 470 (M)+, 393 (M − Ph)+, 378 (393 − Me)+,
322 (M − C8H7PN)+, 271 (M − PhPC6H4NH)+, 200 (M −
CH2C(Me)2CH2PhPC6H4NH2)+. Fraction 3: (RP*,RP*,RP*)- and
(RP*,RP*,SP*)-CH3C(CH2PhPC6H4NH2-2)3 (0.50 g, 28%). 1H
1
NMR and 31P{ H} NMR spectra identical to an authentic sample.
1
[OC -6-22-(RP*,RP*,RP*)]-[1,1,1-Tris{(2-aminophenyl)phenyl-
phosphinomethyl}ethane-N3P3]cobalt(III) chloride, [Co{(RP*,RP*,
RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3 and [OC-6-23-(RP*,
RP*,SP*)]-chloro-[1,1,1-tris{(2-aminophenyl)phenylphosphino-
methyl}ethane-N2P3]cobalt(III) chloride, [CoCl{(RP*,RP*,SP*)-
CH3C(CH2PPhC6H4NH2-2)3}]Cl2. The P3N3 hexadentate lig-
and (RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PhPC6H4NH2-
2)3 (2.75 g, 4.12 mmol) was dissolved in hot methanol (30 mL).
Hexaaquacobalt(II) chloride (1.71 g, 7.19 mmol) in methanol
(20 mL) was added and the reaction mixture refluxed gently
for 1 h. Hydrochloric acid (6 mL) was added and air drawn
through the solution for a period of 4 h. The solvent was
removed from the brown solution and the residue dried in vacuo.
The residue (4.40 g) was dissolved in the minimum volume of
methanol (60 mL) and the resulting brown solution loaded onto
an ion-exchange column [270 × 25 mm, Dowex 50WX8, cation
exchange resin]. The column was eluted with HCl–methanol
(1 mol L−1, elution rate ca. 2 mL min−1). The first compound
eluted was unchanged hexaaquacobalt(II) chloride (0.70 g). A
red band eluted from the column was [CoCl{(RP*,RP*,SP*)-
CH3C(CH2PPhC6H4NH2-2)3}]Cl2 exclusively (2.41 g, 70% based
on (RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PhPC6H4NH2-
Co, 5.36; Cl, 3.22; F, 20.72%). H NMR (CD3OD): d 1.93 (s, 3
H, CCH3); 2.87 (m, 6 H, PCH2); 6.45–7.80 (m, 27 H, aromatics).
1
31P{ H} NMR (CD3OD): d 18.2 (br s, P); 45.4 (br s, P); 61.1
−
(br s, P). LR-ESI MS: m/z 1055 ([CoLCl]2+ + 2PF6 + H+)+,
1039 ([CoLCl]2+ + 2PF6 − Me)+, 873 ([CoL]3+ + PF6−)+, 858
−
([CoL]3+ + PF6 − Me)+, 726 ([CoL]3+ − 2H)+ where L =
−
(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3.
Reaction of [Li(tmeda)][2-NHC6H4PPh2] with CH3C(CH2-
OTs)3. Isolation of (2-diphenylphosphinophenyl)tolyl-4-sulfona-
mide, 2-(4-CH3C6H4SO2)NHC6H4PPh2, and [3-{(2-diphenyl-
phosphinophenyl)aminomethyl}]-3-methyloxetane. A solution of
n-butyllithium in n-hexane (25 mL, 1.6 M, 0.0399 mol) was added
to dry diethyl ether (120 mL) and the solution cooled to 0 ◦C. Solid
adpp (11.09 g, 0.0399 mol) was added to the stirred solution
followed by tmeda (4.65 g, 0.0399 mol). The solution was decanted
off the resulting white solid of [Li(tmeda)][2-NHC6H4PPh2], the
latter washed with diethyl ether (5 × 50 mL) and dried in vacuo
(13.7 g, 86%). The latter (13.7 g, 0.040 mol) was suspended in
benzene (100 mL) and CH3C(CH2OTs)3 (4.66 g, 8.00 mmol) added
to the stirred suspension. The reaction mixture was heated under
reflux for 12 d and cooled to ambient temperature. Aqueous
ammonium chloride solution (100 mL, 20% w/v) was added, the
resulting two phases separated and the aqueous phase extracted
with dichloromethane (3 × 70 mL). The combined organic
phases were dried (MgSO4), filtered and the solvent removed via
distillation under argon at 1 atm. The crude yellow oil was dried
in vacuo. Yield 11.2 g. The oily product was extracted with hot
methanol (4 × 50 mL). The combined methanol extracts were left
standing at ambient temperature for 4 h and the white solid formed
filtered off, washed with cold methanol (3 × 3 mL) and dried to
give the sulfonamide as white microcrystals (2.22 g, 64% based on
tritosylate, 1 : 1), mp 140–140.5 ◦C. 1H NMR (CD2Cl2): d 2.30 (s, 3
1
2)3). H NMR (CD3OD): d 1.94 (br s, 2 H, CH3); 2.87 (m, 6 H,
1
PCH2); 6.44–7.75 (m, 27 H, aromatics). 31P{ H} NMR (CD3OD):
d 60.3 (br s, 1 P); 44.5 (br s, 1 P); 18.7 (br s, 1 P). The last
fraction was collected with HCl–methanol (3 mol L−1, elution rate
ca. 2 mL min−1) and contained exclusively [Co{(RP*,RP*,RP*)-
CH3C(CH2PPhC6H4NH2-2)3}]Cl3 (0.76 g, 22% based on
(RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PhPC6H4NH2-
1
2)3). H NMR (CD3OD): d 2.05 (d, 3 H, CH3); 3.08 (br s, 6 H,
1
PCH2); 6.69–7.65 (m, 27 H, aromatics). 31P{ H} NMR (CD3OD):
d 54.6 (br s, 3 P).
1
[OC-6-22-(RP*,RP*,RP*)]-[1,1,1-Tris{(2-aminophenyl)phenyl-
H, CH3); 6.87–7.87 (m, 19 H, aromatics and NH). 31P{ H} NMR
1
phosphinomethyl}ethane-N3P3]cobalt(III)
hexafluorophosphate,
(CD2Cl2): d −26.2 (s, 1 P). 13C{ H} NMR (CD2Cl2): 21.7 (s, 1 C,
[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2 -2)3 }](PF6 )3.
A
CH3), 121.3–144.2 (m, 24 C, aromatics). m/z 431 (M)+, 367 (M −
SO2)+, 276 (M − SO2C6H4Me)+, 183 (M − NHSO2C6H4Me)+.
The residual material was separated on a silica column (15 ×
2.5 cm, silica gel 70–230 mesh, eluent petroleum spirit (bp 40–
60 ◦C)–dichloromethane, gradient 90 : 10 → 0 : 100) under
nitrogen to give three fractions. Fraction 1: adpp (4.1 g, 37% based
on starting adpp, 43% based on [Li(tmeda)][2-NHC6H4PPh2]). 1H
solution of ammonium hexafluorophosphate (0.12 g, 0.74
mmol) in water (20 mL) was added slowly to a solution of
[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3 (0.05 g,
0.06 mmol) in methanol (5 mL) and left standing overnight.
The resulting yellow precipitate was collected and washed
with water (3 × 5 mL). The complex was recrystallised from
acetone–isopropyl alcohol to give yellow crystals (0.038 g, 55%),
mp 245 ◦C (decomp.) (Found: C, 41.81; H, 3.71; N, 3.53. Calc.
1
NMR and 31P{ H} NMR spectra identical to an authentic sample.
1
Fraction 2: sulfonamide (0.3 g, 9%). 1H NMR and 31P{ H} NMR
1
for C41H42P3N3CoP3F18·H2O: C, 41.68; H, 3.75; N, 3.56%). H
spectra identical to an authentic sample. Fraction 3: oxetane (1.5 g,
4620 | Dalton Trans., 2006, 4614–4622
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Table 3 Crystallographic data for the complexes [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)3·C3H6O, A, and trans-[PtClMe{2-
Ph2PC6H4NH(SO2C6H4CH3-4)}2], B
A
B
Empirical formula
M
T/K
C41H42Co F18N3P6·C3H6O
1221.62
200
C51H47ClN2O4P2PtS2
1108.55
200
Crystal system
Space group
Crystal size/mm
Monoclinic
C2/c
Monoclinic
P21/n
0.52 × 0.30 × 0.03
27.1248(3)
10.8041(1)
34.2865(4)
92.1000(4)
10041.2(2)
8
0.46 × 0.11 × 0.05
11.1852(2)
17.7100(3)
11.7952(1)
92.8833(8)
2333.55(6)
2
˚
a/A
˚
b/A
˚
c/A
b/◦
3
˚
V/A
Z
Dc/g cm−3
1.616
0.639
1.578
3.269
l/mm−1
Reflections collected
Independent reflections
Indep. observed reflections
Rint
62384
8844
5526 (I > 2r(I))
0.08
0.0350, 0.0382
6–50
50772
5360
3107 (I > 3r(I))
0.05
0.0227, 0.0259
6–55
Final R, Rw
2h Range/◦
Parameters
658
292
52% based on tritosylate). 1H NMR (CD2Cl2): d 1.14 (s, 3 H, CH3);
3.26 (m, 2 H, CH2N); 4.21 (m, 4 H, OCH2); 4.58 (br s, 1 H, NH);
pressure and the residual oil dissolved in water (30 mL) and
dichloromethane (20 mL). The resulting phases were separated
and the aqueous phase extracted further with dichloromethane
(2 × 20 mL). The combined organic extracts were dried (MgSO4),
filtered and the solvent removed under reduced pressure. The
residual oil (0.63 g) was separated on a silica column (12 ×
2.5 cm, silica gel 70–230 mesh, eluent petroleum spirit (bp
40–60 ◦C)–dichloromethane, gradient 90 : 10 → 0 : 100) under
nitrogen to give two fractions. Fraction 1: ( )-app (0.29 g, 35%
1
6.61–7.36 (m, 14 H, aromatics). 31P{ H} NMR (CD2Cl2): −19.4
1
(s, 1 P). 13C{ H} (CD2Cl2): d 22.0 (s, 1 C, CH3), 40.0 (s, 1 C, Cq),
51.3 (s, 1 C, CH2N), 80.5 (s, 2 C, CH2O), 110.4–151.2 (m, 18 C,
aromatics). LR-EI MS: m/z 361 (M)+, 346 (M − Me)+, 316 (M −
C2H5O)+, 290 (M − C4H7O)+, 276 (M − C5H9O)+. HR-EI MS:
Found (M)+ 361.1589 (calc. for C23H24NOP: 361.1596).
[SP-4-3]-Chlorobis{(2-diphenylphosphinophenyl)tolyl-4-sulfo-
nylamide-P}methylplatinum(II), trans-[PtClMe{2-Ph2PC6H4NH-
(SO2C6H4CH3-4)}2]. The sulfonamide 2-(4-CH3C6H4SO2)-
NHC6H4PPh2 (0.117 g, 0.273 mmol) was dissolved in dry thf
(10 mL). The complex [PtClMe(cod)] (0.048 g, 0.137 mmol) in thf
(10 mL) was added dropwise to the stirred solution. The reaction
mixture was stirred for 30 min and n-pentane (40 mL) added.
The white precipitate that formed was filtered off, washed with
n-pentane (2 × 2 mL) followed by diethyl ether (2 × 2 mL) and
1
based on starting ( )-app). 1H NMR and 31P{ H} NMR identical
to an authentic sample. Fraction 2, oxetane (0.26 g, 67% based
1
on tritosylate). H NMR (CD2Cl2): d 1.29 (s, 3 H, CH3); 2.38
2
(m, 2 H, PCH2); 4.10 (d, 1 H, JHH = 5.8 Hz, OCHa); 4.14 (d, 1
2
2
H, JHH = 5.7 Hz, OCHb); 4.28 (d, 1 H, JHH = 5.8 Hz, OCHc);
2
4.30 (d, 1 H, JHH = 5.8 Hz, OCHd); 4.20 (br s, 2 H, NH2);
6.52–7.38 (m, 9 H, aromatics). 31P{ H} NMR (CD2Cl2): −41.7
1
(s, 1 P). 13C{ H}APT (CD2Cl2): d 25.5 (d, 1 C, JCP = 16.4 Hz,
1
3
1
2
CH3), 37.3 (d, 1 C, JPC = 13.1 Hz, PCH2), 39.4 (d, 1 C, JPC
=
◦
dried in vacuo (0.12 g, 80%), mp 195–196 C (decomp.) (Found:
15.6 Hz, CH3Cq), 83.4 (m, 2 C, CH2O), 115.6–150.9 (m, 12 C,
aromatics). LR-EI MS: m/z 285 (M)+, 270 (M − Me)+, 254 (M −
CH3O)+, 200 (M − C5H9O)+. HR-EI MS m/z: Found 285.1284
(C17H20NOP requires 285.1283).
C, 54.39; H, 4.31; N, 2.15. Calc. for C51H47P2N2O4S2PtCl·H2O:
1
C, 54.37; H, 4.38; N, 2.48%). H NMR (CD2Cl2): d 0.27 (t, 3 H,
2JPtH = 78 Hz, 3JPH = 13 Hz, PtCH3); 2.38 (s, 3 H, CH3); 7.04–7.70
1
(m, 36 H, aromatics); 9.33 (s, 1 H, NH). 31P{ H} NMR (CD2Cl2):
1
d 22.7 (s, 2 P, 1JPtP = 2916 Hz). 13C{ H} APT (CD2Cl2): d 1.14 (s,
X-Ray crystallography
1 C, PtMe), 21.7 (s, 2 C, CMe), 120.0–144.1 (m, 18 C, aromatics).
Reaction of Na[2-PPhC6H4NH2] with CH3C(CH2OTs)3. Iso-
lation of ( )-[3-{(2-aminophenyl)phenylphosphino}]-3-methyl-
oxetane. Secondary phosphine ( )-app (0.833 g, 4.14 mmol)
was dissolved in thf (40 mL) and sodium foil (0.105 g, 4.14 mmol)
added piecewise to the stirred solution. The reaction mixture was
stirred overnight. The resulting red metal phosphide solution was
X-Ray diffraction data for [Co{(RP*,RP*,RP*)-CH3C(CH2-
PPhC6H4NH2-2)3}](PF6)3.·C3H6O, A, and trans-[PtClMe{2-
Ph2PC6H4NH(SO2C6H4CH3-4)}2], B, were obtained on a Nonius
Kappa CCD diffractometer using Mo-Ka radiation. Details
of the data collections, solutions and refinements are given in
Table 3. The structures were solved using SIR92 and refined using
CRYSTALS.31,32 Analytical absorption corrections were applied
to the data for both A and B (max./min. transmission factors
0.981/0.807 and 0.858/0.431, respectively).33,34
◦
cooled to −78 C and CH3C(CH2OTs)3 (0.804 g, 1.37 mmol) in
thf (20 mL) added slowly dropwise to the stirred solution. The
reaction mixture was allowed to warm to room temperature and
stirred for 3 days. Solid ammonium chloride (2 g) followed by
water (2 mL) were added. The solvent was removed under reduced
B is centred on a crystallographic inversion centre. The structure
of B was initially refined with two chloro groups bound to the
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platinum(II) centre. However, the displacement parameters of the
Cl atom were larger than those of the Pt and P atoms and
there was a major peak in a difference electron density map
between the Pt and Cl atoms which was consistent with the
presence of statistically disordered Cl and methyl groups. This
has previously been reported for the related complexes trans-
[PtClMe(PR3)2] (where R = Et or Ph).20,35 To model this effect
C(26) was included between the Pt and Cl atoms; both C(26) and
the Cl atom were assigned occupancies of 0.5 and constrained to
have equal displacement parameters. Initially the Pt–C and Pt–Cl
distances were restrained to values reported for related complexes
that did not have the Cl/Me disorder,18,36 but for the final cycles
of refinement the restraints were removed. Distances and angles
involving the Cl and C(26) atoms are probably not reliable as these
12 R. J. Doyle, N. Habermehl, G. Salem and A. C. Willis, J. Chem. Soc.,
Dalton Trans., 2000, 3603.
13 For example: M. DiVaira, P. Innocenti, S. Moneti, M. Peruzzini and P.
Stoppioni, Inorg. Chim. Acta, 1984, 83, 161; M. Kita, K. Kashibawara,
J. Fujita, H. Tanaka and S. Ohba, Bull. Chem. Soc. Jpn., 1994, 67,
2457; S. Chatterjee, R. J. Doyle, D. C. R. Hockless, G. Salem and
A. C. Willis, J. Chem. Soc., Dalton Trans., 2000, 1829; M. Kita, K.
Kashibawara and J. Fujita, Bull. Chem. Soc. Jpn., 1988, 61, 3187; and;
T. Ohishi, K. Kashibawara, H. Ito, T. Ito and J. Fujita, Bull. Chem.
Soc. Jpn., 1983, 56, 1551.
14 P. G. Kerr, P. H. Leung and S. B. Wild, J. Am. Chem. Soc., 1987, 109,
4321; J. W. L. Martin, F. S. Stephens, K. D. V. Weerasuria and S. B.
Wild, J. Am. Chem. Soc., 1988, 110, 4346.
15 B. Bosnich, W. G. Jackson and S. B. Wild, J. Am. Chem. Soc., 1973, 95,
8269.
16 L. Horner and W. Hofer, Tetrahedron Lett., 1965, 3281.
17 J.-F. Pilard and J. Simonet, Tetrahedron Lett., 1997, 38, 3735.
18 R. Bardi and A. M. Piazzesi, Inorg. Chim. Acta, 1981, 47, 249.
19 M. A. Bennett, H.-K. Chee and G. B. Robertson, Inorg. Chem., 1979,
18, 1061.
˚
sites are only separated by 0.27(2) A.
20 R. Bardi, A. M. Piazzesi and G. Bruno, Cryst. Struct. Commun., 1981,
10, 807.
21 A. D. Pra, G. Zanotti, G. Bombieri and R. Ros, Inorg. Chim. Acta,
1979, 36, 121.
22 C. J. Cardin, D. J. Cardin, M. F. Lappert and K. W. Muir, J. Chem.
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1973, 12, 224.
CCDC reference numbers 609895 and 609896.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b607847h
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4622 | Dalton Trans., 2006, 4614–4622
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