Capping calixarenes with metallodiphosphine fragments: Towards intracavity reactions

Article abstract of DOI:10.1039/a701954h

The co-ordinative properties of four disubstituted 5,11,17,23-tetra-tert-butyl-25,27-di-RCH ₂O-26,28-bis(diphenylphosphinomethoxy)calix[4]arenes [R = C(O)NEt₂ L¹, C(O)OEt L², (A)-C(O)NHCH(Me)Ph L³ or CH₂OMe L⁴] have been investigated. Compound L¹ reacted with [Au(thf)(SC₄H₈)]BF₄ (thf = tetrahydrofuran, SC₄H₈ = tetrahydrothiophene) and AgBF₄ to yield the chelate complexes [AuL¹]BF₄ 1 and [AgL¹]BF₄ 2, respectively. Reaction of L¹ with trans-[PtH(Cl)(PPh₃)₂] resulted in quantitative formation of trans-[PtH(Cl)L¹] 3 in which the platinum hydrogen bond is partially encapsulated within the calixarene cavity. The structurally related cationic complexes [PtH(PPh₃)Lⁱ]BF₄ (Lⁱ = L¹ 4, L³ 5 or L⁴ 6), having a PPh₃ ligand trans to the hydrido ligand, were obtained in high yield by treating trans-[PtH(thf)(PPh₃)₂]BF₄ with diphosphine L¹. Abstraction of the chloride ion from 3 with AgBF₄ gave [PtH(L¹)]BF₄ 7, a complex in which the calixarene behaves as a tridentate P₂O_amide ligand and in which the metal plane caps one end of the calixarene tunnel. Reaction of 7 with PPh₃ resulted in substitution of the co-ordinated amide to form 4, while reaction with 4,4′-bipyridine gave the binuclear complex [(L¹)HPt(4,4′-bipy)PtH(L¹)][BF⁴] ₂ 8. Reaction of trans-[PtH(Cl)(PPh₃)₂] with Lⁱ resulted in a mixture of complexes of general formula [PtH(PPh₃)Lⁱ]Cl (type A) and [PtH(Cl)Lⁱ] (type B). The A:B ratio depends on the co-ordinating ability of the R groups, since these act as internal solvent molecules in promoting PPh₃ substitution. For R groups containing strong donors, eg. as in L¹ and L², complexes of type B are favoured; with L⁴ the reaction leads selectively to [PtH(PPh₃)L⁴]Cl, no B-type complex being formed. In at least one case (L³) it was shown that complexes of type A may be converted into the B type. Reaction of 7 with dimethyl acetylenedicarboxylate gave the insertion product trans-P,P′-[Pt(MeO₂CC=CHCO₂Me)L¹]BF ₄ where the two amides compete for co-ordination. Complex 7 reacted instantaneously with tetracyanoethylene (tcne) to yield the platinum(0) complex [Pt(tcne)L¹] for which NMR spectra suggest fast flipping of the co-ordination plane between amides. In contrast to [Pt(MeO₂CC=CHCO₂Me)L¹]BF₄, strong tridentate P₂O co-ordination abounds in the rhodium carbonyl complexes [Rh(CO)Lⁱ]BF₄ (Lⁱ = L¹ or L³) obtained from [Rh(CO)₂(thf)₂]BF₄ and the corresponding diphosphines.

Full text of DOI:10.1039/a701954h

View Article Online / Journal Homepage / Table of Contents for this issue
Capping calixarenes with metallodiphosphine fragments:
towards intracavity reactions†
Catherine Wieser,a Dominique Matt,*,a Jean Fischer b and Anthony Harrimanc
a
Groupe de Chimie Inorganique Moléculaire, Université Louis Pasteur, URA 416 CNRS,
1 rue Blaise Pascal, F-67008 Strasbourg Cedex, France
b Laboratoire de Cristallochimie et Chimie Structurale, Université Louis Pasteur,
4 rue Blaise Pascal, F-67070 Strasbourg Cedex, France
c Laboratoire de Photochimie, Ecole Européenne de Chimie, Polymères et Matériaux,
Université Louis Pasteur, 1 rue Blaise Pascal, F-67008 Strasbourg Cedex, France
The co-ordinative properties of four disubstituted 5,11,17,23-tetra-tert-butyl-25,27-di-RCH2O-26,28-
bis(diphenylphosphinomethoxy)calix[4]arenes [R = C(O)NEt2 L1, C(O)OEt L2, (R)-C(O)NHCH(Me)Ph L3 or
CH2OMe L4] have been investigated. Compound L1 reacted with [Au(thf)(SC4H8)]BF4 (thf = tetrahydrofuran,
SC4H8 = tetrahydrothiophene) and AgBF4 to yield the chelate complexes [AuL1]BF4 1 and [AgL1]BF4 2,
respectively. Reaction of L1 with trans-[PtH(Cl)(PPh3)2] resulted in quantitative formation of trans-[PtH(Cl)L1] 3
in which the platinum hydrogen bond is partially encapsulated within the calixarene cavity. The structurally
related cationic complexes [PtH(PPh3)Li ]BF4 (Li = L1 4, L3 5 or L4 6), having a PPh3 ligand trans to the hydrido
ligand, were obtained in high yield by treating trans-[PtH(thf)(PPh3)2]BF4 with diphosphine Li. Abstraction of the
chloride ion from 3 with AgBF4 gave [PtH(L1)]BF4 7, a complex in which the calixarene behaves as a tridentate
P2Oamide ligand and in which the metal plane caps one end of the calixarene tunnel. Reaction of 7 with PPh3
resulted in substitution of the co-ordinated amide to form 4, while reaction with 4,4Ј-bipyridine gave the binuclear
complex [(L1)HPt(4,4Ј-bipy)PtH(L1)][BF4]2 8. Reaction of trans-[PtH(Cl)(PPh3)2] with Li resulted in a mixture of
complexes of general formula [PtH(PPh3)Li ]Cl (type A) and [PtH(Cl)Li] (type B). The A:B ratio depends on the
co-ordinating ability of the R groups, since these act as internal solvent molecules in promoting PPh3 substitution.
For R groups containing strong donors, e.g. as in L1 and L2, complexes of type B are favoured; with L4 the reaction
leads selectively to [PtH(PPh3)L4]Cl, no B-type complex being formed. In at least one case (L3) it was shown that
complexes of type A may be converted into the B type. Reaction of 7 with dimethyl acetylenedicarboxylate gave
the insertion product trans-P,PЈ-[Pt(MeO CC᎐CHCO Me)L1]BF where the two amides compete for co-
᎐
2
2
4
ordination. Complex 7 reacted instantaneously with tetracyanoethylene (tcne) to yield the platinum(0) complex
[Pt(tcne)L1] for which NMR spectra suggest fast flipping of the co-ordination plane between amides. In contrast
to [Pt(MeO CC᎐CHCO Me)L1]BF , strong tridentate P O co-ordination abounds in the rhodium carbonyl
᎐
2
2
4
2
complexes [Rh(CO)Li]BF4 (Li = L1 or L3) obtained from [Rh(CO)2(thf)2]BF4 and the corresponding diphosphines.
But
Calix[4]arenes are a class of readily accessible macrocyclic
compounds that have become significant in supramolecular
chemistry during the last decade.1–11 They are frequently
employed as platforms that permit functional groups to be
oriented to provide well organized cavities or clefts. Tethering
of pendant arms to such a preorganizing matrix may be
achieved at the phenolic oxygen atoms12–14 and/or at the para
positions15–18 of calix[4]arenes. Recent synthetic work con-
cerned with the functionalization of calix[4]arenes has led to
the isolation of novel cavity-shaped podands displaying highly
selective complexation properties toward certain metal ions,19,20
and facilitating encapsulation of neutral21 or anionic10 sub-
strates. It should be emphasized here that when such selective
receptors contain additional redox-responsive functionalities
they allow quantitative detection of complexed species, and
hence constitute valuable tools for analytical purposes.22
Of particular interest in this area are the calix[4]arene-based
transition-metal complexes.11,23–36 Indeed, it might be antici-
pated that structures having a metal centre lying close to the
mouth of a calix[4]arene pocket would possess interesting
catalytic properties with respect to the transformation of suit-
ably shaped substrates. Furthermore, the presence of a high
number of converging functional groups located close to a
catalytic centre might control the stereochemistry of the reac-
OH
HO
But
But
OH
OH
But
p-tert-butylcalix[4]arene
tion and discriminate between several incoming substrates. It is
clear that other synergistic effects might be envisaged. We note,
however, that studies dealing with the reactivity of organo-
metallic species bound to a calixarene unit remain scarce.11,37
In a preliminary report we have outlined the preparation of
an encapsulated hydrido ligand, obtained by entrapment of the
‘H᎐Pt᎐Cl’ fragment by the cone calixarene L1 (see below), con-
taining the key elements of a diphosphine and two neighbour-
ing amide functions.38 Structural studies showed that the
diphosphine acts as a trans-chelator and that the platinum–
hydrogen bond lies within the space defined by the four lower-
† Non-SI units employed: bar = 101325 Pa.
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2391

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But But
But
But
But But
But
But
But But
But
But
(i)
O
O
O
O
OH
OH
O
O
OH
OH
HO
OH
R
R
OMe
MeO
PPh2
L4a 75 %
Ph2P
Li
(ii)
L1 R = C(O)NEt2
L2 R = C(O)OEt
L3 R = (R)-C(O)NHCHMePh
L4 R = CH2OMe
But But
But
But
rim substituents of the calixarene and is directed toward the
centre of the cavity. We now report full synthetic procedures for
this work and describe additional hydrides obtained from
diphosphines bearing other auxiliary groups.
O
O
O
O
O
The chemistry reported herein illustrates our basic strategy
for the preparation of reactive organometallic fragments
located inside or close to a molecular pocket. This approach
uses suitably derivatized diphosphinocalixarenes as scaffolds
for specific metal fragments. The main advantage of our
methodology is that the pendant phosphines are logically sited
so as to position the organometallic centre at the mouth of the
calixarene cavity. Capped calixarenes of this kind might be
expected to utilize the shape selectivity inherent to the pre-
formed cavity, the size, polarity and functionality of which can
be modulated. An essential feature of our approach is that the
reactive component is directed inside the molecular cavity, so as
to discriminate in favour of bound substrates. Of the numerous
capped calixarenes reported to date, only L1 provides a clear
example of an encapsulated metal–hydrogen bond. We note
that using a different approach, Gardiner et al.39 have recently
obtained an aluminium-capped calix[4]arene derivative pur-
ported to retain an endo-Al᎐H bond, but a structural determin-
ation of this complex remains elusive.
OMe
MeO
(iii)
PPh2
But But
But
But
Ph2P
O
L4b 62 %
O
O
O
O
OMe
MeO
PPh2
Ph2P
L4
80 %
Scheme 1 Preparation of the mixed ether–phosphine L4. Reagents
and conditions: (i) K2CO3 (1.3 equivalents), BrCH2CH2OMe (2.2
equivalents), refluxing MeCN; (ii) NaOBut (2.1 equivalents), p-
MeC6H4SO3CH2P(O)Ph2 (2.2 equivalents), refluxing tetrahydrofuran
(thf)–dimethylformamide (dmf) (9:1); (iii) refluxing SiPhH3
cationic gold species. Its NMR data are consistent with a C2-
symmetrical structure while the chemical shift of the 31P NMR
signal is indicative of a linear AuP2ϩ arrangement.42 The related
silver complex 2 was isolated in high yield by treating L1 with
AgBF4. As for 1, NMR data for 2 show equivalence of both
phosphine arms and both amide groups. The J(109Ag᎐31P) value
(542 Hz, CDCl3) lies in a range typical for [Ag(L᎐L)X] com-
plexes (L᎐L = large diphosphine, X = ClO4 or NO3).43,44 Inter-
estingly, the solution IR spectrum of 2 (thf) shows two strong
absorption bands in the carbonyl region (1660, 1629 cmϪ1),
whereas for 1 a single band was found. The situation with 1 is
normal and indicates that the secondary side arms are uncom-
plexed to the metal centre. In contrast the IR data of 2 reflect
that the two amide functions lie in different environments as
induced by the central silver cation. The most plausible, but
unproven, interpretation of this behaviour is that one of the
carbonyl groups is weakly bonded to the metal. Presumably, the
two amides alternate on a faster time-scale than relevant to
NMR spectroscopy. The tight binding constraint imposed by
the diphosphine requires that additional complexation with a
carbonyl group forms a Y-shaped, rather than a T-shaped,
complex. Stable examples of Y-shaped complexes formed from
silver() appear to be known.44
Results and Discussion
In order to strap a transition-metal centre across the mouth of
a calix[4]arene it is necessary to attach suitable co-ordinating
moieties on distal sites. Owing to their ubiquitous complexing
ability,40 terminal phosphine groups have been selected for the
pendant arms, which are kept short to maximize localization
of the metal centre. The phosphine groups can be attached at
the phenolic oxygen atoms, leaving two further sites where
secondary co-ordinating functions can be appended. In order
to establish suitable metal complexes assembled at the phos-
phine ligands, calixarenes L1–L4 have been used since these
provide the required stereochemical features. These compounds
retain a common diphosphine but differ in the nature of the
secondary side arms. Synthetic procedures for L1–L3 have been
described before,27,28 but compound L4 having ether functions
is reported here for the first time. This latter compound, each
arm of which has two weakly co-ordinating oxygen atoms, is
conveniently prepared in a three-step synthesis according to
Scheme 1, in 37% yield. Compounds L1–L4 allow a gradation of
secondary binding sites and, according to NMR spectroscopy,41
possess the desired cone conformation.
Synthesis of encapsulated and semiencapsulated hydrides
The ability of the diphosphine function to entertain trans-
P,PЈ complexation with metal centres was first explored
towards Auϩ and Agϩ, since such complexes require no add-
itional ligation.
In an effort to increase the co-ordination number of the bound
metal, and to employ metals possessing more versatile catalytic
properties, attention was turned to the synthesis of platinum
complexes. By treating the amidephosphine L1 with trans-
[PtH(Cl)(PPh3)2] in CH2Cl2 ligand exchange occurred, resulting
in quantitative formation of the hydrido complex 3 (Scheme 3)
which was fully characterized. An important point to emerge
from the structural analysis is that vapour-phase osmometry
Compound L1 was treated with [Au(thf)(SC4H8)]BF4
(SC4H8 = tetrahydrothiophene) in CH2Cl2 at room temperature
(Scheme 2), giving complex 1 in high yield, apparently free
of polymeric structures. The FAB mass spectrum of 1 shows
an intense peak at 1467, corresponding to the mononuclear
2392
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402

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+
H
Pt
thf
+
+
+
But But
–
But
But
BF4
t But
But
But
–
–
Bu
O
BF4
BF4
Ph3P
PPh3
[Au(thf)(SC4H8)]BF4
CH2Cl2-thf
O
O
thf
O
O
O
Au
1
O
O
O
O
But But
But
But
NEt2
H
Et2N
PPh2
R
PPh2
Ph2P
Pt
R
Ph2P
PPh3
O
O
O
O
R
R
But But
But
But
4 R = C(O)NEt2
PPh2
5 R = (R)-C(O)NHCHMePh
6 R = CH2OMe
Ph2P
L1 R = C(O)NEt2
L3 R = (R)-C(O)NHCHMePh
L4 R = CH2OMe
O
O
O
O
O
O
NEt2
Et2N
Scheme 4
PPh2
Ph2P
crystallography.38 It is interesting that the formation of 3
requires exchange of the ligated phosphines. It seems likely that
such ligand exchange is promoted by the polar amide groups
present in L1, since the analogous reaction did not occur with
phosphine L4. The latter differs from L1 only by virtue of the
co-ordinating ability of the auxiliary side arms.
L1
+
But But
But
But
–
BF4
The presence of the ligated chlorine atom is not mandatory
for complex formation since reaction of trans-[PtH(thf)(PPh3)2]-
BF4 with L1, L3 and L4 gave, respectively, complexes 4–6 in high
yield (Scheme 4). These complexes contain two types of co-
ordinated phosphine. According to NMR spectroscopy the
resultant complexes are C2-symmetrical with the co-ordinated
diphosphines clearly behaving as trans-P,PЈ chelators [J(Pt᎐
AgBF4
O
O
O
O
CH2Cl2-thf
PPh2
O
Et2N
Ag
O
NEt2
Ph2P
2
i
PL ) = 2879, 2879 and 2843 Hz, respectively]. The NMR pattern
of each hydrido ligand appears as a symmetrical pair of triplets
(with platinum satellites) ranging between Ϫ4.19 and Ϫ4.73 {cf.
δ Ϫ15.04 for 3 and Ϫ15.21 for trans-[PtH(Cl)(PPh3)2]}. Interest-
ingly, these hydrido complexes do not transform in solution
into the corresponding cis-diphosphine isomers, thus con-
trasting with certain other complexes of the type [PtH(diphos-
phine)(PPh3)]ϩ that contain a trans-spanning diphosphine.45
Extrusion of the Pt᎐H bond and subsequent isomerization does
not take place in our case, presumably because of favourable
interaction between the hydrido ligand and one or more oxygen
atoms. Such protection against isomerization could be an
essential feature of catalytic reactions where a trans-P,PЈ
configuration needs to be retained.46 It should be noted that our
synthetic strategy is directed toward the partial encapsulation
of the hydride ligand and its subsequent stabilization against
extrusion.
Scheme 2
But But
But
But
H
Ph3P
Pt
Cl
PPh3
+
CH2Cl2
O
O
O
O
O
H
O
NEt2
Et2N
PPh2
Pt
Ph2P
But But
But
O
But
Cl
3
Treatment of complex 3 with AgBF4 in CH2Cl2 gave the
cationic hydrido complex 7, for which IR (KBr) and NMR
spectra unambiguously show one amide group to be free and
the other to be co-ordinated (Scheme 5). We consider, therefore,
that one pendant carbonyl group fills the vacant co-ordination
site. This has the effect of displacing the other carbonyl group
away from the metal centre. One important stereological feature
of 7 is that the regions immediately above and below the
platinum centre are markedly disparate, such environmental
asymmetry being rare in platinum chemistry.45 The P2O ligand
may be regarded as an hemispherical ligand strapping the metal
centre across the mouth of the calixarene. There is no indi-
O
O
O
O
O
NEt2
Et2N
PPh2
Ph2P
L1
Scheme 3
clearly showed that the complex was monomeric. A two-
dimensional ROESY (rotating frame Overhauser enhancement
spectroscopy) experiment, performed on a 500 MHz spec-
trometer, indicated that the hydrido ligand is in close proximity
with each OCH2 group of the pendant arms and also with the
axial H atoms of the bridging C6H2CH2C6H2 units. This sug-
gests that the hydrido ligand is directed into the mouth of the
calixarene cavity defined by the four phenolic oxygen atoms.
This configuration has been confirmed by single-crystal X-ray
1
cation that the amide groups interconvert and the H NMR
spectra remain essentially independent of temperature over the
range Ϫ30 to ϩ80 ЊC in C2D2Cl4.
The co-ordinated amide group was readily replaced by
adventitious donors, such as PPh3 or 4,4Ј-bipyridine yielding,
respectively, the mononuclear complex 4 and the binuclear
complex 8 (Scheme 5). This extrusion and subsequent complex-
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2393

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+
But But
But
But
But But
But
But
-
BF4
(ii)
(i)
4
O
O
O
O
O
O
H
O
O
O
O
O
NEt2
Et2N
PPh2
NEt2
PPh2
Pt
O
Et2N
Pt
Ph2P
H
Ph2P
Cl
7
3
(iii)
2+
2 BF4
Et2N
NEt2
O
But
O
But
–
Ph2
P
O
Ph2
P
O
But
But
But
But
O
O
O
N
N
Pt
H
H
Pt
O
O
P
P
O
Ph2
Ph2
But
But
O
O
Et2N
NEt2
8
Scheme 5 Reagents and conditions: (i) AgBF4 (1 equivalent), in CH2Cl2; (ii) PPh3 (1 equivalent), in CH2Cl2; (iii) 4,4Ј-bipyridine (1 equivalent),
in CHCl3
ation strategy provides a valuable route to the synthesis of novel
calixarene-derived platinum hydrides. In the two examples
quoted the hydride ligand is reinserted inside the molecular
pocket. In this way the electronic properties of the hydride
can be varied over a wide range simply by judicious selection
of the external ligand while linear bimetallic complexes can
be assembled around different ditopic bridges. It should be
possible to change both the length of the spacer and the
extent of electronic coupling between the platinum centres
whilst maintaining all other structural attributes.
was clearly demonstrated, at least in the case of L3, that the
chloride became co-ordinated to the platinum centre upon heat-
ing. We may surmise, therefore, that a PPh3 (diphosphine) com-
plex of type A is formed as an intermediate. The corresponding
intermediate for L1 was not observed, reaction always proceed-
ing to completion, and was found for L4 only under forcing
conditions (Scheme 6).
Formation of these intermediate species occurs by way of
ejection of the chloride and of one PPh3 ligand from the incom-
ing organometallic species. The results displayed in Scheme 6
indicate that the nature of the auxiliary side arms has a pro-
found effect upon the rate of conversion of A into B. Strong
donor sites, such as provided by amide and ester functions,
promote loss of the bound PPh3 ligand, thereby facilitating
formation of the chloro complex. These ligands can be con-
sidered to function as internal solvation sites that induce ligand
substitution. The effect is partially lost when the size of the
auxiliary side arm is extended, presumably due to steric crowd-
ing, and reaction with L3 is incomplete. This auxiliary effect in
which the side arm promotes loss of a tightly bound triphenyl-
phosphine residue is not restricted to the second step in the
overall assemblage but must play a part in formation of com-
plexes of type A. Indeed, without the co-operative assistance of
the auxiliary sites it is not possible to realize the first substitu-
tion step in significant yield. Finally, it should be mentioned
here that the use of hemilabile phosphines, i.e. bearing second-
ary groups of weak co-ordinating power, has recently proved
to be essential for increasing the rate of certain catalytic
reactions.47,48
Role of the auxiliary functions for the formation of hydrides of
type 3
Assemblage of our basic building block 3 is accomplished via
ligand exchange and it is noteworthy that reaction involves
insertion of a sterically congested diphosphine. The driving
force for such ligand exchange is far from obvious but several
important factors probably contribute towards the initial
reaction and stabilization of the emerging bis(phosphine)
complex. First, it has proved essential that the basicity of the
calixarene-derived residue exceeds that of the incoming [PtH-
(Cl)(PRЈ3)2] complex (e.g. exchange does not occur with [PtH-
(Cl){P(C6H11)3}2]). Thus, the first step is driven by the higher
co-ordinative properties of the Ph2P-calix moiety. Since the co-
ordination sites in L1–L4 show higher affinity for platinum than
does PPh3 we might expect similar complexation to occur with
each of these compounds. However, whereas L1 gives the
platinum complex in high yield, L4, being similar in size to L1,
does not react with the platinum precursor. This comparison
suggests that the auxiliary functions play an active role in
formation of the chelate complex. In trying to rationalize the
relative reactivity of L1–L4 it becomes clear that chelate form-
ation takes place via a stepwise process for which stable inter-
mediates could be isolated in some cases (Scheme 6).
Substitution reactions at the metal centre
Compounds such as 3 comprise a calixarene cavity, a diphos-
phinometal fragment, and an encapsulated metal hydride. Such
entities are stable but treatment with silver tetrafluoroborate
results in removal of the chloride ligand, providing access to
intermediary reagents such as 7. An important feature inherent
to complex 7 is that the hydride is displaced from the cavity and
is readily accessible to species in solution. This permits evalu-
ation of the ability of the Pt᎐H bond to enter into insertion
The course of reaction was followed by NMR spectroscopy
and it was observed that with L2 and L3 an additional product
(type A in Scheme 6) was apparent in the reaction mixture.
These products, being reminiscent of the BF4Ϫ salts 4–6, have a
triphenylphosphine residue in place of the chloride ligand. It
2394
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402

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But
But
Table 1 Selected bond lengths (Å) and angles (Њ) for complex 12ؒ3
CHCl3ؒH2O
But
But
Pt᎐P(1)
Pt᎐P(2)
2.277(1)
2.300(1)
2.109(5)
2.105(5)
1.815(5)
1.823(5)
1.845(4)
1.850(4)
1.823(5)
1.820(4)
O(1)᎐C(1)
1.387(5)
1.410(5)
1.403(4)
1.400(5)
1.428(7)
1.439(8)
1.152(7)
1.122(7)
1.453(7)
1.428(9)
O(2)᎐C(30)
O(4)᎐C(43)
O(5)᎐C(67)
C(83)᎐C(84)
C(86)᎐C(87)
C(84)᎐N(3)
C(87)᎐N(5)
C(83)᎐C(85)
C(86)᎐C(88)
Pt᎐C(83)
Pt᎐C(86)
P(1)᎐C(8)
P(1)᎐C(14)
P(1)᎐C(7)
P(2)᎐C(48)
P(2)᎐C(49)
P(2)᎐C(55)
O
O
O
O
R
R
PPh2
Ph2P
a
1 L1 R = C(O)NEt2
P(1)᎐Pt᎐P(2)
C(83)᎐Pt᎐C(86)
Pt᎐P(1)᎐C(7)
101.38(4)
106.1(1)
120.1(4)
P(1)᎐C(7)᎐O(1)
P(2)᎐C(48)᎐O(4)
Pt᎐P(2)᎐C(48)
111.0(3)
109.6(2)
120.5(4)
2
3
4
5
L2 R = C(O)OEt a
L3 R = C(O)NHC*H(Ph)Mea
L4 R = CH2OMea
L4 R = CH2OMeb
the complex obtained after completion of the reaction shows
an intense peak at m/z 1609.9. This establishes that a molecule
1
dmad has been inserted. Furthermore, the H NMR spectrum
H
exhibits two distinct MeO signals each of intensity 3 H and an
olefinic CH proton (δ 5.16), consistent with 11. The 31P NMR
spectrum displays a solitary signal at δ 16.4 with corresponding
platinum satellites. The J(PPt) coupling constant (2926 Hz) is
clearly indicative of a trans arrangement of the phosphorus
atoms.
Pt
Ph3P
PPh3
Cl
But
But
+
The NMR spectra show equivalence of each amide and
phosphino group over the temperature range Ϫ80 to ϩ50 ЊC.
These observations, taken together with the need for a square-
planar metal plane, require a fluxional structure for complex 11,
possibly involving fast exchange between co-ordinated and free
amide groups (Scheme 7). Note, the solution IR spectrum (as
well as the KBr spectrum) shows strong carbonyl bands which
may be assigned to free and co-ordinated amide functions in
addition to the ester groups (see Experimental section). As
such, the platinum centre present in 11 is considered to possess
three tightly bound ligands, with the fourth co-ordination site
being occupied alternately by one of the amide oxygen donors.
This alternation of the auxiliary side arm persists at Ϫ80 ЊC.
The bonded alkenyl fragment resembles a pendulum moving
between the amido terminals, presumably on a fast time-scale,
thereby creating a pseudo-C2 symmetry about the molecular
axis. This fast exchange process may be driven by the high trans
influence of the alkenyl groups weakening the Pt᎐O bond.
Again, the auxiliary side arms provide key elements in the
overall process by stabilizing the insertion product.
But
But
But
But
But
But
Cl-
+
O
O
O
O
O
O
O
O
R
H
R
H
R
R
PPh2
PPh2
Pt
Pt
Ph2P
Ph2P
PPh3
Cl
B
A
3' (0 %)
9' (5 %)
5' (55 %)
6' (0 %)
6' (100 %)
3 (100 %)
9 (80 %)
10 (44 %)
6 (0 %)
6 (0 %)
The above reaction involves hydride transfer from metal to
alkyne, leading to formation of a stable insertion product. In
marked contrast, treatment of complex 7 with tcne in CHCl3
results in formation of the corresponding π complex 12
(Scheme 8). This product arises from reductive elimination and
is formed in quantitative yield under ambient conditions.
Irrefutable proof of the formation of a platinum(0) species
accrued from an X-ray diffraction study (Fig. 1, Table 1). The
solid-state structure shows that the macrocyclic subunit dis-
plays a geometry typical for cone conformers.50 More import-
antly, the metal atom is no longer centred under the cavity but
is considerably displaced to one side, the metal plane making a
dihedral angle of about 40Њ with the calixarene reference plane.
This forces one of the neighbouring auxiliary side arms to lie
orthogonal to the cavity. Formation of 12 requires loss of the
hydrido ligand, with simultaneous conversion of PtII into Pt0
and co-ordination of the electrophilic species. Such reductive
elimination reactions have been observed with related, but non-
calixarene-derived, trans-diphosphine complexes.51 Since this
transformation proceeds rapidly we may surmise that there are
no undue stereological barriers to adoption of the necessary cis
configuration.
Scheme 6 Product distribution for the reaction of Li with trans-
[PtH(Cl)(PPh3)2]. Reaction conditions: a CH2Cl2, room temperature,
5 d (full conversion of the substrate, except for entry 4, 0%); b thf,
reflux, 24 h. For the reactions with L2 and L3 trace amounts of
other unidentified hydrido complexes were detected. The numbers in
parentheses indicate selectivities
and/or substitution reactions. It is prudent to establish that
such reactions can take place outside the cavity where the
substrate experiences less severe stereochemical constraints
before attempting to design systems where the chemistry takes
place within the cavity. Consequently, the reactivity of 7 was
investigated towards incoming electrophiles, namely dimethyl
acetylenedicarboxylate (dmad) and tetracyanoethylene (tcne).
Compound 3 does not react with dmad, even at elevated
temperature, but following activation to 7 reaction proceeded
smoothly in CH2Cl2 (Scheme 7). This reaction, which was
followed by 31P NMR spectroscopy, involves formation of a
transient species having two non-equivalent, cis-bonded phos-
phorus atoms [J(PPt) = 4541 and 2028 Hz]. By analogy to the
findings of Venanzi,49 we tentatively assign this intermediate to
the structure shown in Scheme 7. The FABϩ mass spectrum of
Detailed examination of the NMR spectrum indicates that
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2395

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+
But
But
But
But
–
BF4
+
But
But
But
But
–
BF4
O
O
O
(i)
O
O
NEt2
O
O
O
O
Et2N
O
O
PPh2
Ph2P
NEt2
Pt
PPh2
O
Et2N
Pt
solv
MeO2C
Ph2P
H
H
7
MeO2C
+
+
But
But
But
But
But But
But
BF4
But
–
–
BF4
O
O
O
O
O
O
O
O
P
Et2N
NEt2
O
P
O
O
NEt2
O
Et2N
Pt
Pt
MeO2C
CO2Me
Ph2P
PPh2
H
H
CO2Me
MeO2C
11
᎐
Scheme 7 Reagents and conditions: (i) MeO2CC᎐CCO2Me (1.1 equivalent, 3 d, in CDCl3)
᎐
complex 12 has apparent C2 symmetry in solution. In partic-
ular, unlike in the solid state, the auxiliary side arms are equiv-
alent. As outlined above for complex 11, we envisage that the
bis(phosphine) residue must undergo large-scale torsional
motion of the type depicted in Scheme 9.
auxiliary side arms since NMR and IR spectroscopy clearly
indicate the presence of both a complexed and a free carbonyl
(C᎐Oamide). In the rhodium complex, therefore, exchange
᎐
between the amido functions must be slow and the pendulum
effect described with 11 is not apparent. The realization that
substitution products could not be observed upon treating 13 or
14 with strong donors such as PPh3 or pyridine confirms our
contention that one of the amido groups is tightly bound to the
rhodium centre.
The organometallic fragment present in complexes 13 and 14
possesses the key features known to be important for hydro-
formylation catalysts. Indeed, 13 catalyses the conversion of
styrene into the corresponding aldehydes in toluene–CH2Cl2
mixtures under 40 bar CO ϩ H2 (1:1) at 40 ЊC. Selectivity of
linear to branched aldehydes (n :i) lies in the order of 5:95,
which is unexceptional for rhodium() bis(phosphine) com-
plexes. The frequency of turnover (0.5 per h) was extremely low
indicating a steric barrier to reaction. Note, hydrogenation of
Towards intracavity reactions
Bis(phosphine) compounds such as L1–L4 have proved to be
suitable ligands for the assembly of capped calixarenes bearing
reactive metal centres. These ligands are versatile and should
enable formation of metal complexes which might display use-
ful catalytic functions. In fact a major goal of this program is to
design capped calixarenes that combine catalytic activity of the
metal cap with the size-exclusion capability of the macrocyclic
receptor. Such processes are difficult to realize with platinum
centres because of their unfavourable steric demands but may
be more accommodated with rhodium hydrides.
The rhodium() complexes 13 and 14 were prepared by treat-
ing [Rh(CO)2(thf)2]BF4 with L1 and L3, respectively (Scheme
10). An interesting feature of this latter compound is that it
contains two chiral centres which make the two phosphorus
atoms in 14 non-equivalent. This is apparent in the 31P NMR
spectrum where the ABX pattern (X = Rh) confirms the trans
arrangement [J(PP) = 331 Hz]. In the absence of a chiral centre
(13) the phosphorus atoms are equivalent. This is not so for the
cyclohexene with 14 (PH = 50 bar, 60 ЊC) in MeOH also led to
2
low catalytic activity (turnover frequency ca. 145 per h).
Based on our structural findings with the relevant hydrido-
platinum complex 3 we might expect that the rhodium hydrido
precursor, which must be the reactive intermediate in hydro-
formylation, also has a protected rhodium–hydrogen bond.
Such a structure is not conducive to ready transfer of the
hydride or carbonyl moieties to the incoming olefin. In order
2396
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402

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But
O
But
But
But
But
But
O
–
But
BF4
But
But But
But
But
R′′O
R′′O
OR′′
OR′′
O
O
O
P
P
O
O
O
O
P
P
NEt2
Pt
PPh2
Pt
O
Et2N
Pt
C
C
H
Ph2P
C
C
7
Scheme 9 Proposed dynamics for complex 12
NC
CN
CH2Cl2
But But
But
But
NC
CN
t But
Bu
But
But
O
O
O
O
O
O
NR′′′R′′′′
R′′′R′′′′N
O
O
Et2N
PPh2
O
O
O
O
Ph2P
NEt2
PPh2
CN
CN
1 R′′′ = R′′′′ = Et
L3 R′′′ = H, R′′′′ = (R)-CHMePh
Ph2P
NC
Pt
L
CN
[Rh(CO)2(thf)2]BF4
CH2Cl2
12
Scheme 8
+
–
BF4
O
O
O
O
O
H
H
H
H
NR′′′R′′′′
PPh2
CO
R′′′R′′′′N
O
Rh
Ph2P
13
14
Scheme 10
Fig. 1 Crystal structure of a molecule of complex 12 with partial
labelling scheme. Only the ipso-carbon atoms of the phenyl rings are
shown
centre and hence the results presented here open up the way for
studying synergistic effects of functional groups surrounding a
reactive metal centre located inside a molecular pocket. The
particular structures of the hydrido-complexes presented in this
work allow us to study reactions inside or outside a molecular
cavity.
better to accommodate selective homogeneous catalysis, it
seems necessary to enlarge the domain bordered by the four
functional arms. This could be done by extending the arms but
retaining the balance between strong and weak complexation
sites.
In summary, we have shown that the hemispherical diphos-
phines L1–L4 derived from 1,3-difunctionalized calix[4]arenes
are suitable for the preparation of transition-metal hydrides
having the hydrido ligand encapsulated within the cavity gener-
ated by the four substituents. We have presented a synthetic
methodology that allows modulation of the chemical properties
of the entrapped hydrides and for modifying their environment.
It was found that the presence of auxiliary binding functions
can be helpful for promoting substitution reactions at the metal
Experimental
All manipulations involving phosphines were performed in
Schlenk-type flasks under argon. Solvents were dried by con-
ventional methods and distilled immediately prior to use;
CDCl3 was passed down a 5 cm thick alumina column and
stored under argon over molecular sieves (4 Å). Infrared spectra
were recorded on a Perkin-Elmer 1600 spectrometer (4000–400
cmϪ1) and a Bruker FIR spectrometer (500–90 cmϪ1), routine
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2397

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1H, 31P-{1H} and 13C-{1H} NMR spectra with an FT Bruker
WP-200 SY instrument, 500 MHz spectra on an ARX 500
Bruker instrument. The 1H NMR spectral data were referenced
to residual protiated solvents (δ 7.27 for CDCl3), 13C chemical
shifts relative to deuteriated solvents (δ 77.0 for CDCl3), and the
31P data relative to external H3PO4. Mass spectra of compounds
L4a, L4b and L4 were recorded on a TSQ-70 Finnigan-Mat
spectrometer and those of 1–7 and 9–14 on a ZAB HF VG
Analytical spectrometer using m-nitrobenzyl alcohol or tetra-
glyme (2,5,8,11,14-pentaoxapentadecane) as matrix. The
molecular weight determinations by vapour-pressure osmo-
metry were performed by Analytische Laboratorien, Lindlar,
Germany. Samples of p-tert-butylcalix[4]arene,52 5,11,17,23-
tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-
bis(diphenylphosphinomethoxy)calix[4]arene L1,28 5,11,17,23-
tetra-tert-butyl-25,27-di(ethoxycarbonylmethoxy)-26,28-bis-
(diphenylphosphinomethoxy)calix[4]arene L2,27 (R,R)-(ϩ)-
5,11,17,23-tetra-tert-butyl-25,27-bis[(1-phenylethyl)carbamoyl-
methoxy]-26,28-bis(diphenylphosphinomethoxy)calix[4]arene
L3,28 Ph2P(O)CH2O3SC6H4Me-p,53 [AuCl(SC4H8)],54 [PtH-
(Cl)(PPh3)2]55 and [{RhCl(CO)2}2]56 were prepared using liter-
ature procedures.
The catalytic runs (hydroformylation of styrene with com-
plex 13) were performed in a 100 cm3 glass-lined steel autoclave
containing a magnetic stirring bar. In a typical experiment,
a solution of 13 (0.025 g, 0.017 mmol) in toluene–CH2Cl2
(14:3 v/v, 15 cm3) was introduced under argon into the auto-
clave. The autoclave was pressurized (20 bar) with CO–H2 (1:1)
and heated to 40 ЊC for 2 h. After cooling and depressurization
styrene was introduced (1 cm3, ca. 0.906 g, 8.70 mmol). The
autoclave was then pressurized again with CO–H2 (1:1), at 40
bar, and heated to 40 ЊC. After 144 h the autoclave was cooled
and then slowly opened. The liquid phase was analysed by GC.
At this stage the conversion was 12%. The linear :branched
aldehyde ratio was 5:95.
added and the solution refluxed for 24 h. After filtration, the
solvent was removed under reduced pressure. The residue was
taken up in CH2Cl2 (100 cm3) and washed with saturated
NH4Cl–water (2 × 100 cm3) and then with water (100 cm3). The
organic layer was dried over MgSO4 and concentrated to ca. 20
cm3. Addition of acetone with stirring and cooling gave a white
microcrystalline deposit (2.9 g, 62%), m.p. 227–228 ЊC. IR
1
(KBr, cmϪ1): ν(P᎐O) 1208s (tentative). NMR (CDCl ): H, δ
᎐
3
7.83–7.74 and 7.47–7.40 (2m br, 20 H, PPh2), 6.77 and 6.44 (2s,
8 H, m-H), 5.01 (s, 4 H, OCH2PPh2), 4.42 and 2.92 (AB spin
system, 8 H, C6H2CH2C6H2, 2J = 12.8), 3.94 and 3.82 (2m, 8 H,
OCH2CH2O), 3.25 (s, 6 H, OCH3), 1.12 [s, 18 H, C(CH3)] and
0.93 [s, 18 H, C(CH3)]; 13C-{1H}, δ 153.59–124.55 (aromatic C),
72.48 and 72.00 (2s, OCH2CH2O), 72.02 [d, OCH2PPh2,
J(PC) = 80 Hz], 58.14 (s, OCH3), 33.63 and 33.45 [2s, C(CH3)],
31.32 [s, C(CH3)], 31.21 (s, C6H2CH2C6H2) and 31.06 [s,
C(CH3)]; 31P-{1H}, δ 24.9 (s, PPh2). Chemical ionization (CI)
mass spectrum: m/z (%) 1193.8 (100), Mϩ (Found: C, 76.64; H,
7.84. C76H90O8P2 requires C, 76.48; H, 7.60%).
5,11,17,23-Tetra-tert-butyl-25,27-bis(diphenylphosphino-
methoxy)-26,28-bis(3-oxabutyloxy)calix[4]arene, cone L4. A
solution of L4b (2.900 g, 2.43 mmol) in phenylsilane (20 cm3)
was refluxed for 72 h. After cooling, unreacted phenylsilane was
removed under reduced pressure and recovered for reuse. The
residue was taken up in CH2Cl2 (ca. 5 cm3) and addition of
EtOH with stirring and cooling afforded the product as a white
1
powder (2.3 g, 80%), m.p. 228–230 ЊC. NMR (CDCl3): H, δ
7.53–7.45 and 7.31–7.29 (2m br, 20 H, PPh2), 6.93 and 6.53 (2s,
2
8 H, m-H), 4.87 [d, 4 H, OCH2PPh2, J(PH) = 3.4], 4.35 and
3.05 (AB spin system, 8 H, C6H2CH2C6H2, 2J = 12.5 Hz), 4.01–
3.90 (m, 8 H, OCH2CH2O), 3.33 (s, 6 H, OCH3), 1.23 [s, 18 H,
C(CH3)] and 0.93 [s, 18 H, C(CH3)]; 13C-{1H}, δ 153.89–124.48
(aromatic C), 72.26 (s, OCH2), 71.74 (s, OCH2), 58.48 (s,
OCH3), 33.74 and 33.48 [2s, C(CH3)], 31.39 [s, C(CH3)], 31.24
(s, C6H2CH2C6H2) and 31.02 [s, C(CH3)]; 31P-{1H}, δ Ϫ21.9 (s,
PPh2). CI mass spectrum: m/z (%) 1161.6 (100), Mϩ (Found: C,
78.65; H, 7.86. C76H90O6P2 requires C, 78.59; H, 7.81%).
Preparations
5,11,17,23-Tetra-tert-25,27-dihydroxy-26,28-bis(3-oxabutyl-
oxy)calix[4]arene L4a. A suspension of p-tert-butylcalix[4]arene
(5.000 g, 7.71 mmol) in acetonitrile (200 cm3) was stirred at
room temperature overnight with K2CO3 (1.380 g, 10.01 mmol).
2-Bromoethyl methyl ether (2.36 g, 16.94 mmol) was then
added and the mixture refluxed for 3 d. During this period three
additional portions of BrCH2CH2OMe (1.50 mmol for each
addition) and K2CO3 (1.50 mmol) were added after 24, 36 and
60 h. Reaction was followed by TLC [Rf = 1 (starting com-
pound);0.49(monoalkylated compound); 0 (L4a); SiO2, CH2Cl2].
After filtration, the solvent was removed in vacuo. The residue
was dissolved in CH2Cl2 (100 cm3) and the resultant solution
was washed first with saturated NH4Cl–water (2 × 100 cm3) and
subsequently with water (100 cm3). The organic layer was dried
over MgSO4. After filtration, the purified product was precipi-
tated with EtOH to yield a white solid (4.4 g, 75%), m.p. 222—
223 ЊC. IR (KBr, cmϪ1): ν(OH) 3360–3314 (br). NMR (CDCl3):
1H, δ 7.40 (s, 2 H, OH), 7.15 and 7.06 (2s, 8 H, m-H), 4.39 and
{5,11,17,23-Tetra-tert-butyl-25,27-bis(diethylcarbamoyl-
methoxy)-26,28-bis(diphenylphosphinomethoxy)calix[4]arene}-
gold(I) tetrafluoroborate 1. A solution of AgBF4 (0.024 g, 0.122
mmol) in thf (1 cm3) was added to a solution of [AuCl(SC4H8)]
(0.039 g, 0.122 mmol) in CH2Cl2 (3 cm3). Stirring was stopped
after 5 min and the solution was decanted in order to remove
AgCl. The supernatant was filtered over Celite and added to a
solution of L1 (0.155 g, 0.122 mmol) in CH2Cl2 (30 cm3). After
2 h the solution was concentrated to ca. 1 cm3 and addition
of pentane afforded the product as an analytically pure white
powder (0.160 g, 84%), m.p. 238–240 ЊC (decomp.). IR (KBr,
cmϪ1): ν(C᎐O) 1654s and ν(B᎐F ) 1058s (br). NMR (CDCl ):
᎐
3
1H, δ 7.91–7.82 and 7.59–7.43 (20 H, PPh2), 7.05 (s, 4 H, m-H),
6.37 (s, 4 H, m-H), 5.70 (s, 4 H, OCH2PPh2), 3.94 (s, 4 H,
OCH2CONEt2), 3.91 and 2.83 (AB spin system, 8 H,
2
3
C6H2CH2C6H2, J = 12.8), 3.47 (q, 4 H, NCH2CH3, J = 6.7),
3.05 (q, 4 H, NCH2CH3, 3J = 6.7), 1.34 (s, 18 H, But), 1.22 (t, 12
H, NCH2CH3, 3J = 6.7), 1.08 (t, 12 H, NCH2CH3, 3J = 6.7) and
2
3.32 (AB spin system, 8 H, C6H2CH2C6H2, J = 12.9 Hz), 4.17
0.78 (s, 18 H, But); 13C-{1H}, δ 166.88 (s, C᎐O), 155.42–125.06
and 3.89 (2m, 8 H, OCH2CH2O), 3.56 (s, 6 H, OCH3), 1.30 [s, 18
H, C(CH3)] and 0.99 [s, 18 H, C(CH3)]; 13C-{1H}, δ 150.28–
116.50 (aromatic C), 75.05 (s, OCH2), 71.23 (s, OCH2), 59.10 (s,
OCH3), 33.81 and 33.63 [2s, C(CH3)], 31.50 [s, C(CH3)], 31.35
(s, C6H2CH2C6H2) and 30.91 [s, C(CH3)]. Electron Impact (EI)
mass spectrum: m/z (%) 764.4 (100), Mϩ (Found: C, 78.22; H,
8.85. C50H68O6 requires C, 78.49; H, 8.96%).
᎐
(aromatic C), 72.36 (s, OCH2CONEt2), 72.01 [t, OCH2PPh2,
|J(PC) ϩ 3J(PЈC)| = 41 Hz], 40.46 and 40.05 (2s, NCH2CH3),
34.06 and 33.55 [2s, C(CH3)3], 31.56 and 30.94 [2s, C(CH3)3],
30.24 (s, C6H2CH2C6H2), 14.07 and 13.08 (2s, NCH2CH3);
31P-{1H}, δ 36.9 (s, PPh2). FAB mass spectrum: m/z (%) 1467.6
(100), [M Ϫ BF4]ϩ (expected isotopic profile) (Found: C, 61.98;
H, 6.16. C82H100AuBF4N2O6P2ؒ0.5 CH2Cl2 requires C, 62.01; H,
6.37%).
5,11,17,23-Tetra-tert-butyl-25,27-bis(diphenylphosphinoyl-
methoxy)-26,28-bis(3-oxabutyloxy)calix[4]arene, cone L 4b. A
solution of L4a (3.000 g, 3.9 mmol) in thf–dmf (9:1 v/v, 100
cm3) was refluxed with NaOBut (0.791 g, 8.23 mmol) for 1 h.
Then Ph2P(O)CH2O3SC6H4Me-p (3.300 g, 8.6 mmol) was
{5,11,17,23-Tetra-tert-butyl-25,27-bis(diethylcarbamoyl-
methoxy)-26,28-bis(diphenylphosphinomethoxy)calix[4]arene}-
silver(I) tetrafluoroborate 2. To a solution of L1 (0.150 g, 0.118
2398
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402

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3
3
mmol) in CH2Cl2 (20 cm3) was added a solution of AgBF4
(0.025 g, 0.129 mmol) in thf (1 cm3). After stirring for 5 min the
suspension was filtered over Celite. The pale pink solution was
concentrated to ca. 1 cm3 and addition of pentane afforded the
product as an analytically pure precipitate (pale pink) (0.126 g,
NCH2CH3, J = 7.0), 3.02 (q, 4 H, NCH2CH3, J = 7.0), 1.40
(t, 6 H, NCH2CH3, J = 7.0), 1.28 (s, 18 H, But), 1.05 (t, 6 H,
3
3
NCH2CH3, J = 7.0), 0.74 (s, 18 H, But) and Ϫ4.31 [dt with
2
2
platinum satellites, 1 H, PtH, J(HPcis) = 16, J(HPtrans) = 168,
J(HPt) = 774]; 13C-{1H}, δ 167.44 (s, C᎐O), 155.39–124.44
᎐
74%), m.p. >280 ЊC (slow decomp.). IR (cmϪ1): (Nujol) ν(C᎐O)
(aromatic C), 73.21 [t, OCH2PPh2, |J(PC) ϩ 3J(PЈC)| = 52],
72.18 (s, OCH2CONEt2), 40.83 and 40.25 (2s, NCH2CH3),
33.78 and 33.45 [2s, C(CH3)3], 31.43 and 30.87 [2s, C(CH3)3],
30.07 (s, C6H2CH2C6H2), 14.08 and 13.16 (2s, NCH2CH3); 31P-
{1H}, δ 22.35 [t with platinum satellites, PPh3, 2J(PPЈ) = 20,
J(PPt) = 2020] and 14.38 (d with platinum satellites, PPh2,
2J(PPЈ) = 20, J(PPt) = 2879 Hz]. FAB mass spectrum: m/z (%)
1467.6 (100), [M Ϫ PPh3 Ϫ BF4]ϩ (Found: C, 64.79; H, 6.38; N,
1.46. C100H116BF4N2O6P3Ptؒ0.5CH2Cl2 requires C, 64.90; H,
6.35; N, 1.50%).
᎐
1654s, 1620s and ν(B᎐F ) 1058s (br); (thf) 1660s and 1629s.
1
NMR (CDCl3): H, δ 7.71–7.32 (20 H, PPh2), 6.99 (s, 4 H,
m-H), 6.32 (s, 4 H, m-H), 5.69 (s br, 4 H, OCH2PPh2), 4.09 (s,
4 H, OCH2CONEt2), 3.86 and 2.80 (AB spin system, 8 H,
2
3
C6H2CH2C6H2, J = 12.8), 3.48 (q, 4 H, NCH2CH3, J = 7.0),
3.12 (q, 4 H, NCH2CH3, 3J = 7.0), 1.34 (s, 18 H, But), 1.21 (t, 12
H, NCH2CH3, 3J = 7.0), 1.13 (t, 12 H, NCH2CH3, 3J = 7.0) and
0.76 (s, 18 H, But); 13C-{1H}, δ 167.11 (s, C᎐O), 155.42–125.14
᎐
(aromatic C), 72.62 (m, OCH2PPh2, signal of low intensity),
72.18 (s, OCH2CONEt2), 40.54 and 40.28 (2s, NCH2CH3),
33.92 and 33.45 [2s, C(CH3)3], 31.46 and 30.77 [2s, C(CH3)3],
30.25 (s, C6H2CH2C6H2), 13.90 and 12.87 (2s, NCH2CH3);
31P-{1H}, δ Ϫ0.93 [2d, PPh2, J(P109Ag) = 542, J(P107Ag) = 469
Hz]. FAB mass spectrum: m/z (%) 1379.6 (100), [M Ϫ BF4]ϩ
(expected isotopic profile) (Found: C, 67.36; H, 6.68; N, 1.73.
C82H100AgBF4N2O6P2 requires C, 67.17; H, 6.87; N, 1.91%).
trans-P,PЈ-(R,R)-Hydrido{5,11,17,23-tetra-tert-butyl-25,27-
bis[(1-phenylethyl)carbamoylmethoxy]-26,28-bis(diphenylphos-
phinomethoxy)calix[4]arene}(triphenylphosphine)platinum(II)
tetrafluoroborate 5. A solution of AgBF4 (0.021 g, 0.110 mmol)
in thf (1 cm3) was added to a stirred solution of [PtH(Cl)-
(PPh3)2] (0.083 g, 0.110 mmol) in CH2Cl2 (3 cm3). Stirring was
stopped after 5 min and the solution was decanted in order to
remove AgCl. The supernatant and dichloromethane washings
of the AgCl precipitate were filtered through Celite into a solu-
tion of L3 (0.150 g, 0.110 mmol) in CH2Cl2 (30 cm3). After
strirring for 24 h the solution was concentrated to ca. 2 cm3 and
addition of pentane afforded a white precipitate (0.150 g, 75%),
trans-P,PЈ-Chlorohydrido{5,11,17,23-tetra-tert-butyl-25,27-
bis(diethylcarbamoylmethoxy)-26,28-bis(diphenylphosphino-
methoxy)calix[4]arene}platinum(II) 3. To a solution of L1
(0.178 g, 0.24 mmol) in CH2Cl2 (15 cm3) was added dropwise a
solution of trans-[PtH(Cl)(PPh3)2] (0.300 g, 0.24 mmol) in
CH2Cl2 (15 cm3). After stirring for 5 d the solution was concen-
trated to ca. 5 cm3 and pentane was added to yield complex 3 as
m.p. 179–182 ЊC. IR (KBr, cmϪ1): ν(C᎐O) 1676s and ν(B᎐F )
1054 (br). NMR (CDCl3): H, δ 7.37–6.86 (m, 49 H, aromatic
H), 6.50 (d, 2 H, NH, J = 6.9), 6.26 (s br, 4 H, m-H), 5.70 and
᎐
1
3
an analytically pure white powder. It was dried in vacuo (0.325
1
g, 90%), m.p. 254–255 ЊC. IR (KBr, cmϪ1): ν(C᎐O) 1658s. H
5.56 [AB spin system with platinum satellites, 4 H, OCHAHB-
PPh2, J(AB) = 9.8, J(HPt) ≈ 46], 5.26 (dq, AMX3 spin system, 2
᎐
NMR (CDCl3): δ 7.93–7.91 and 7.42 (m br, 20 H, PPh2), 7.12 (s,
4 H, m-H), 6.53 (s, 4 H, m-H), 5.35 [s with platinum satellites,
4 H, OCH2PPh2, J(HPt) = 33], 4.63 and 3.04 (AB spin system,
H, NHCHMePh, JAM ≈ 3JAX = 6.9), 4.34 and 4.22 (AB spin
3
system, 4 H, OCHAHBCONHR, J = 13.8), 3.81 and 2.78 (AB
spin system, 4 H, C6H2CH2C6H2, J = 13.1), 3.63 and 2.55 (AB
spin system, 4 H, C6H2CH2C6H2, J = 13.1), 1.53 (d, 6 H,
NHCHCH3Ph, 3J = 5.9), 1.28 (s, 18 H, But), 0.75 (s, 18 H, But)
2
8 H, C6H2CH2C6H2, J = 13.0), 4.12 (s, 4 H, OCH2CONEt2),
3
3.21 (q, 4 H, NCH2CH3, J = 7.1), 2.77 (q, 4 H, NCH2CH3,
3
3J = 7.1), 1.35 (s, 18 H, But), 1.01 (t, 6 H, NCH2CH3, J = 7.0),
2
0.99 (t, 6 H, NCH2CH3, 3J = 7.1), 0.81 (s, 18 H, But) and Ϫ15.04
[t with platinum satellites, 1 H, PtH, 2J(HP) = 15, J(HPt) = 1150
Hz]. 1H NMR (C6D6): δ Ϫ14.22 [t with platinum satellites, PtH,
2J(HP) = 15, J(PtH) = 1150 Hz]. 13C-{1H} NMR (CDCl3): δ
and 4.73 [dt with platinum satellites, 1 H, PtH, J(HPcis) = 18,
2J(HPtrans) = 169, J(HPt) = 762]; 13C-{1H}, δ 168.77 (s, C᎐O),
᎐
155.24–124.78 (aromatic C), 74.17 [dt, OCH2PPh2, |J(PC) ϩ
3J(PtransC)| ≈ 60, J(PcisC) = 5], 73.73 (s, OCH2CONHR), 48.76
2
168.00 (s, C᎐O), 154.71–124.73 (aromatic C), 71.27 (s, OCH -
(s, NHCHMePh), 33.84 [s, C(CH3)3], 33.48 [s, C(CH3)3], 31.52
[s, C(CH3)3], 30.96 [s, C(CH3)3], 30.05 (s, C6H2CH2C6H2) and
22.09 (s, NHCHCH3Ph); 31P-{1H}, δ 22.7 [t with platinum
᎐
2
CONEt2) 70.24 [t, OCH2PPh2, |J(PC) ϩ 3J(PЈC)| = 51 Hz],
40.33 and 39.64 (2s, NCH2CH3), 33.96 and 33.51 [2s, C(CH3)3],
31.93 (s, C6H2CH2C6H2), 31.67 and 31.07 [2s, C(CH3)3], 14.18
and 12.99 (2s, NCH2CH3). 31P-{1H} NMR (CDCl3): δ 22.7
[s with platinum satellites, PPh2, J(PPt) = 3122 Hz]. FAB mass
spectrum: m/z (%) 1467 (100), [M Ϫ Cl]ϩ. M(Osmometry,
2
satellites, PPh3, J(PPЈ) = 20, J(PPt) ~ 2006] and 15.9 (d with
2
platinum satellites, PPh2, J(PPЈ) = 20, J(PPt) = 2879 Hz). FAB
mass spectrum: m/z (%) 1824.7 (2), [M Ϫ BF4]ϩ (expected iso-
topic profile); 1563.6 (100), [M Ϫ PPh3 Ϫ BF4]ϩ (Found: C,
67.61; H, 6.12; N, 1.31. C108H116BF4N2O6P3Pt requires C, 67.81;
H, 6.11; N, 1.46%).
CH2Cl2): 1490 (Found: C, 62.79; H, 6.74; N, 1.60. C82H101
-
ClN2O6P2PtؒCH2Cl2 requires C, 62.77; H, 6.54; N, 1.76%).
trans-P,PЈ-Hydrido{5,11,17,23-tetra-tert-butyl-25,27,bis-
(diethylcarbamoylmethoxy)-26,28-bis(diphenylphosphino-
trans-P,P-Hydrido{5,11,17,23-tetra-tert-butyl-25,27-bis-
(diphenylphosphinomethoxy)-26,28-bis(3-oxabutyloxy)calix[4]-
arene}(triphenylphosphine)platinum(II) tetrafluoroborate 6. A
solution of AgBF4 (0.025 g, 0.13 mmol) in thf (1 cm3) was
added to a stirred solution of [PtH(Cl)(PPh3)2] (0.098 g, 0.013
mmol) in CH2Cl2 (3 cm3). Stirring was stopped after 5 min and
the solution was decanted in order to remove AgCl. The super-
natant and dichloromethane washings of the AgCl precipitate
were filtered through Celite into a solution of L4 (0.150 g, 0.13
mmol) in CH2Cl2 (25 cm3). After stirring for 12 h the solution
was concentrated to ca. 2 cm3. Addition of pentane afforded the
product as a pale pink powder (0.163 g, 74%), m.p. 209 ЊC (slow
methoxy)calix[4]arene}(triphenylphosphine)platinum(II) tetra-
fluoroborate 4. A solution of AgBF4 (0.023 g, 0.12 mmol) in thf
(1 cm3) was added to a stirred solution of [PtH(Cl)(PPh3)2]
(0.089 g, 0.12 mmol) in CH2Cl2 (3 cm3). Stirring was stopped
after 5 min and the solution was decanted in order to remove
AgCl. The supernatant and combined dichloromethane wash-
ings of the AgCl precipitate were filtered through Celite into a
solution of L1 (0.150 g, 0.12 mmol) in CH2Cl2 (25 cm3). After
stirring for 12 h, the solution was concentrated to ca. 2 cm3
before addition of pentane afforded the product as a pale
yellow precipitate (0.160 g, 80%), m.p. 188–190 ЊC. IR (KBr,
cmϪ1): ν(C᎐O) 1653, ν(B᎐F ) 1057. NMR (CDCl ): 1H, δ 7.49–
1
decomp.). NMR (CDCl3): H, δ 7.38–7.15 (35 H, PPh), 6.96
and 6.35 (2s, 8 H, m-H), 5.60 [s with platinum satellites, 4 H,
᎐
3
7.08 (35 H, PPh3 and PPh2), 6.93 (s, 4 H, m-H), 6.27 (s, 4 H,
m-H), 5.85 [s with platinum satellites, 4 H, OCH2PPh2,
3J(HPt) = 52], 4.05 (s, 4 H, OCH2CONEt2), 3.88 and 2.68 (AB
spin system, 8 H, C6H2CH2C6H2, 2J = 13.0), 3.66 (q, 4 H,
OCH2PPh2, 3J(HPt) = 51], 3.94 and 2.73 (AB spin system, 8 H,
2
C6H2CH2C6H2, J = 12.8 Hz), 3.77 and 3.47 (2m, 8 H, OCH2-
CH2O), 3.45 (s, 6 H, OCH3), 1.30 [s, 18 H, C(CH3)], 0.76 [s, 18
H, C(CH3)] and Ϫ4.19 [dt, with platinum satellites, 1 H, PtH,
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2399

View Article Online
3J(HPcis) = 14, 3J(HPtrans) = 167, 2J(HPt) = 772]; 13C-{1H}, δ
155.26–124.36 (aromatic C), 74.15 and 70.25 (s, OCH2-
CH2O), 73.02 [t, OCH2PPh2, |J(PC) ϩ 3J(PЈC)| = 55], 58.50 (s,
OCH3), 33.84 and 33.47 [2s, C(CH3)], 31.52 and 31.01 [2s,
C(CH3)] and 30.05 (s, C6H2CH2C6H2); 31P-{1H}, δ 22.0 [t with
H, 6.25; N, 2.32. C174H210B2F8N6O12P4Pt2ؒCHCl3 requires C,
60.21; H, 6.09; N, 2.4%).
trans-P,PЈ-Chlorohydrido{5,11,17,23-tetra-tert-butyl-25,27-
di(ethoxycarbonylmethoxy)-26,28-bis(diphenylphosphino-
2
platinum satellites, PPh3, J(PPЈ) = 20 Hz, J(PPt) = 2009] and
methoxy)calix[4]arene}platinum(II) 9. To a solution of L2 (0.200
g, 0.164 mmol) in CH2Cl2 (15 cm3) was added dropwise a solu-
tion of trans-[PtH(Cl)(PPh3)2] (0.124 g, 0.164 mmol) in CH2Cl2
(15 cm3). After stirring for 3 d the solvent was removed in vacuo.
The residue was adsorbed onto silica gel. Subsequent elution
with CH2Cl2 yielded small amounts of two unidentified
compounds. Further elution with CH2Cl2–MeOH (95:5 v/v)
(Rf = 0.9; SiO2, CH2Cl2–MeOH 95:5) gave 9 (0.170 g, 71%),
15.6 [d with platinum satellites, PPh2, 2J(PPЈ) = 20, J(PPt) =
2843 Hz]. FAB mass spectrum: m/z (%) 1619.7 (20), [M Ϫ BF4]ϩ
(expected isotopic profile): 1357.6 (100), [M Ϫ BF4 Ϫ PPh3]ϩ
(Found: C, 66.24; H, 6.39. C94H106BF4O6P3Pt requires C, 66.15;
H, 6.25%).
trans-P,P-Hydrido{5,11,17,23-tetra-tert-butyl-25-(diethyl-
carbamoylmethoxy)-27-(diethylcarbamoylmethoxy-êO)-26,28-
bis(diphenylphosphinomethoxy)calix[4]arene}platinum(II)
m.p. 170–173 ЊC (slow decomp.). IR (KBr, cmϪ1): ν(C᎐O) 1755s
᎐
and 1727s. NMR (CDCl3): 1H, δ 7.99 (m br) and 7.47 (m br, 20
H, PPh2), 7.12 (s, 4 H, m-H), 6.54 (s, 4 H, m-H), 5.24 [s with
platinum satellites, 4 H, OCH2PPh2, J(HPt) = 51], 4.44 and 2.99
tetrafluoroborate 7. To a solution of complex 3 (0.217 g, 0.14
mmol) in CH2Cl2 (20 cm3) was added a solution of AgBF4
(0.282 g, 0.14 mmol) in thf (1 cm3). After stirring for 30 min the
suspension was filtered through Celite. The filtrate was concen-
trated to ca. 5 cm3. Addition of pentane afforded a pale yellow
precipitate (0.150 g, 70%), m.p. 218–219 ЊC. IR (KBr, cmϪ1):
ν(C᎐O) 1655s, 1606s, ν(B᎐F ) 1060s. NMR (CDCl ): 1H, δ 7.84–
2
(AB spin system, 8 H, C6H2CH2C6H2, J = 12.8), 4.02 (q, 4 H,
3
CO2CH2CH3, J = 6.9), 3.87 (s, 4 H, OCH2CO2CH2CH3), 1.35
(s, 18 H, But), 1.14 (t, 6 H, CO2CH2CH3, 3J = 6.9), 0.81 (s, 18 H,
But) and Ϫ15.00 [t with platinum satellites, 1 H, PtH,
2J(HP) = 14.8, J(HP) = 1154]; 31P-{1H}, δ 23.8 [s with platinum
satellites, PPh2, J(PPt) = 3148 Hz]. FAB mass spectrum: m/z (%)
1412.6 (100), [M Ϫ Cl]ϩ (expected isotopic profile) (Found: C,
64.52; H, 6.51. C78H91ClO8P2Pt requires C, 64.65; H, 6.33%).
᎐
3
7.40 (20 H, PPh2), 7.18 and 7.05 (AB spin system, 4 H, m-H,
4J = 3), 6.54 and 6.33 (2s, 4 H, m-H), 6.23 and 5.01 [ABXXЈ
spin system with X, XЈ = P, 4 H, OCH2PPh2, 2J(AB) = 12,
|J(AX) ϩ J(AXЈ)| = 10, J(BX) not determined], 4.32 and 3.59
(2s, 4 H, OCH2CONEt2), 4.32 and 3.31 (AB spin system, 4 H,
Reaction of trans-[PtH(Cl)(PPh3)2] with L3. This reaction was
followed by 31P NMR spectroscopy (CH2Cl2, external CDCl3).
After 12 h only [PtH(PPh3)L3]Cl 5Ј (ca. 20%) and the starting
complex were detected. Full conversion of the starting complex
was observed after 36 h. At this stage, the reaction mixture
contains 5Ј (80%) and 10 (20%). The reaction mixture was then
heated and slow conversion of 5Ј into 10 was observed. After 5
d the 5Ј:10 ratio was 55:44 (1% of an unidentified hydride was
also detected). Complex 10 was not isolated and its structure
2
3
C6H2CH2C6H2, J = 13), 3.77 (q, 2 H, NCH2CH3, J = 7), 3.55
2
and 2.42 (AB system, 4 H, C6H2CH2C6H2, J = 13), 3.39 (q, 2
H, NCH2CH3, 3J = 7), 3.11 (q, 2 H, NCH2CH3, 3J = 7), 3.09 (q,
3
3
2 H, NCH2CH3, J = 7), 1.41 (t, NCH2CH3, J = 7), 1.36 (s, 18
H, But), 1.15, 1.08 and 0.94 (3t, NCH2CH3, 3J = 7 Hz), 0.84 (s, 9
H, But), 0.75 (s, 9 H, But) and Ϫ22.95 [with platinum satellites,
1 H, PtH, J(HPt) = 1306, 2J(HP) = 15]; 13C-{1H}, δ 170.27
and 166.07 (2s, C᎐O), 155.49–125.21 (aromatic C), 75.67
᎐
1
[t, OCH2PPh2, |J(PC) ϩ J(PЈC)| = 48 Hz], 72.73 and 70.34
(2s, OCH2CONEt2), 40.87, 40.57 and 40.13 (NCH2CH3),
34.21, 33.73 and 33.59 [3s, C(CH3)3], 31.72, 31.09 and 30.98
[3s, C(CH3)3], 31.53 and 29.97 (2s, C6H2CH2C2H2), 14.33,
13.41, 13.19 and 13.05 (4s, NCH2CH3); 31P-{1H}, δ 24.8 [s with
platinum satellites, PPh2, J(PPt) = 3166 Hz). FAB mass spec-
trum: m/z (%) 1467 (100), [M Ϫ BF4]ϩ (Found: C, 61.39;
H, 6.35; N, 1.73. C82H101BF4N2O6P2Ptؒ0.75 CH2Cl2 requires
C, 61.42; H, 6.38; N, 1.73%).
was assigned on the basis of its 31P and its H NMR spectra
(CDCl3). 31P-{1H}, δ 20.5 [s with platinum satellites, PPh2,
1
J(PPt) = 3153]; H, δ Ϫ15.16 [t with platinum satellites, 1 H,
PtH, 2J(HP) = 15.15, J(HP) = 1150 Hz].
trans-P,PЈ-[1,2-Di(methoxycarbonyl)ethenyl]{5,11,17,23-
tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-
bis(diphenylphosphinomethoxy)calix[4]arene}platinum(II)
tetrafluoroborate 11. To a solution of complex 7 (0.200 g,
3
᎐
0.129 mmol) in CDCl (10 cm ) was added MeO CC᎐CCO Me
᎐
3
2
2
ì-4,4Ј-Bipyridine-bis(trans-P,PЈ-hydrido{5,11,17,23-tetra-
tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-
(0.020 g, 0.140 mmol). The reaction was monitored by 31P
NMR spectroscopy. After 3 d the solution was concentrated to
ca. 1 cm3 and pentane was added to yield the product as an
analytically pure white powder (0.180 g, 82%), m.p. 212–215 ЊC
bis(diphenylphosphinomethoxy)calix[4]arene}platinum(II)
bis(tetrafluoroborate) 8. To a solution of complex 7 (0.160 g,
0.103 mmol) in CHCl3 (20 cm3) was added a solution of 4,4Ј-
bipyridine (0.008 g, 0.051 mmol) in CHCl3 (1 cm3). After stir-
ring for 15 h the solution was concentrated to ca. 1 cm3. Add-
ition of pentane afforded the product as an analytically pure
white powder (0.160 g, 92%), m.p. 250–255 ЊC (decomp.). IR
(KBr, cmϪ1): ν(C᎐O) 1654s, ν(B᎐F ) 1057 s (br). NMR (CDCl ):
(decomp.). IR (cmϪ1): (KBr) ν(C᎐O ) 1718s, ν(C᎐O
)
᎐
᎐
amide
ester
1654s, 1632s, 1590s, ν(B᎐F ) 1054s; (thf) ν(C᎐Oester) 1720s,
᎐
ν(C᎐Oamide) 1654s, 1633s, 1590s. The presence of four strong
᎐
ν(C᎐O) absorption bands in the IR spectrum, instead of three,
᎐
suggests that several isomers resulting from dynamics within
the chelate backbone are interconverting (atropisomers). NMR
(CDCl3): 1H, δ 7.88–7.49 (m br, 18 H, PPh2), 7.18 (s, 4 H, m-H),
6.95 (s, 2 H, PPh2), 6.46 (s, 4 H, m-H), 5.59 (br s, 4 H,
OCH2PPh2), 5.16 [s, 1 H, CH(CO2Me)], 4.46 and 3.19 (AB spin
᎐
3
1H, δ 8.47 and 7.30 (AB spin system, 8 H, CH of bipyridine,
3J = 6 Hz),7.57–7.39 (40 H, PPh2), 7.04 (s, 8 H, m-H), 6.42 (s,
8 H, m-H), 5.82 [s with platinum satellites, 8 H, OCH2PPh2,
J(HPt) = 50], 4.32 and 2.89 (AB spin system, 16 H, C6H2CH2-
C6H2, 2J = 12.8), 4.11 (s, 8 H, OCH2CONEt), 3.55 (q, 8 H,
NCH2CH3, 3J = 7.0), 3.08 (q, 8 H, NCH2CH3, 3J = 6.9), 1.36 (t,
2
system, 8 H, C6H2CH2C6H2, J = 13.0), 4.20 (s, 4 H, OCH2-
CONEt2), 3.50 (q, 4 H, NCH2CH3, 3J = 7.3), 3.42 (s, 3 H,
CO2CH3), 3.03 (s, 3 H, CO2CH3), 2.93 (q, 4 H, NCH2CH3,
3
3
12 H, NCH2CH3, J = 7.0), 1.32 (s, 36 H, But), 1.09 (t, 12 H,
3J = 6.4), 1.36 (s, 18 H, But), 1.24 (t, 6 H, NCH2CH3, J = 7.0),
3
3
NCH2CH3, J = 7.0), 0.79 (s, 36 H, But) and Ϫ15.92 [t with
1.01 (t, 6 H, NCH2CH3, J = 7.0) and 0.82 (s, 18 H, But); 13C-
platinum satellites, 2 H, PtH, J(HP) = 15, J(HPt) = 998]; 13C-
{1H} (500 MHz), δ 173.22 (s, CO2CH3), 168.09 [s, C(O)N],
{1H}, δ 167.56 (s, C᎐O), 155.12–123.07 (aromatic C), 71.80 (s,
163.71 (s, CO CH ), 154.03–122.74 (aromatic C and C᎐C),
᎐
᎐
2
3
OCH2CONEt2), 70.04 [t, OCH2PPh2, |J(PC) ϩ 3J(PЈC)| ≈ 55
Hz], 40.60 and 40.45 (2s, NCH2CH3), 33.91 and 33.54 [2s,
C(CH3)3], 31.60 and 31.05 [2s, C(CH3)3], 14.14 and 13.14 (2s,
NCH2CH3), C6H2CH2C6H2 not found; 31P-{1H}, δ 22.3 [s with
platinum satellites, PPh2, J(PPt) = 3072 Hz] (Found: C, 60.07;
72.23 (s, OCH2CONEt2), 70.64 [t, OCH2PPh2, |J(PC) ϩ
3J(PЈC)| = 42], 50.59 and 50.53 (2s, CO2CH3), 40.58 (s,
NCH2CH3), 34.19 and 33.82 [2s, C(CH3)3], 32.96 and 32.80 (s,
C6H2CH2C6H2), 31.60 and 31.06 [2s, C(CH3)3], 13.87 and 13.08
(2s, NCH2CH3); 31P-{1H}, δ 16.4 [s with platinum satellites,
2400
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402

View Article Online
PPh2, J(PPt) = 2926 Hz]. FAB mass spectrum of 11 after re-
crystallisation from CH2Cl2–pentane: m/z (%) 1609.9 (100)
[M Ϫ BF4]ϩ (expected isotopic profile) (Found: C, 62.07; H,
6.11; N, 1.61. C88H107BF4N2O10P2Pt requires C, 62.27; H, 6.36;
N, 1.65%).
stirred solution of [{Rh(CO)2Cl}2] (0.021 g, 0.110 mmol) in
CH2Cl2 (3 cm3). Stirring was stopped after 5 min and the solu-
tion was decanted in order to remove AgCl. The supernatant
and dichloromethane washings of the AgCl precipitate were
filtered through Celite into a solution of L3 (0.150 g, 0.110
mmol) in CH2Cl2 (30 cm3). After stirring for 1 h the solution
was concentrated to ca. 2 cm3 and addition of a diethyl ether–
pentane mixture afforded a white precipitate (0.110 g, 63%),
trans-P,PЈ-{5,11,17,23-Tetra-tert-butyl-25,27-di(ethylcarb-
amoylmethoxy)-26,28-bis(diphenylphosphinomethoxy)calix[4]-
arene}(tetracyanoethene)platinum(0) 12. To a solution of com-
plex 3 (0.100 g, 0.066 mmol) in CHCl3 (10 cm3) was added
m.p. 211–213 ЊC. IR (KBr, cmϪ1): ν(C᎐O) 1988s, ν(C᎐O)
᎐
᎐
᎐
1
1680m, 1634s and ν(B᎐F ) 1054s (br). NMR (CD2Cl2): H, δ
8.05–7.15 (m, 31 H, aromatic H ϩ NH), 7.03 and 7.00 [AB spin
system, 2 H, m-H, J(AB) = 3], 6.66–6.45 (three overlapping AB
(NC) C᎐C(CN) (0.009 g, 0.066 mmol). After stirring for 10 h
᎐
2
2
the solution was concentrated to ca. 1 cm3. Addition of pentane
afforded 12 as an analytically pure pale yellow powder (0.105 g,
3
spin systems, 6 H, m-H), 5.94 (d, 1 H, NH, J = 7.6), 5.68 and
94%), m.p. 252 ЊC (decomp.). IR (KBr, cmϪ1): ν(C᎐O) 1667s,
5.32 [ABXY system, X = P, Y = Rh, 2 H, PCH2, J(AB) = 12,
J(PA) = 8, J(RhA) = 0, J(PB) = 9, J(RhB) = 2 Hz), 5.46 and
5.31 [ABXY system, X = P, Y = Rh, 2 H, PCH2, J(AB) = 12,
J(PA) = 12, J(RhA) = 0, J(PB) = 12, J(RhB) = 3], 4.90 [dq,
AMX3 spin system, 1 H, NHCHMePh, 3J(AM) ≈ 3J(AX) =
7.1], 4.75 [dq, AMX3 spin system, 1 H, NHCHMePh,
3J(AM) ≈ 3J(AX) = 7.1], 4.54 and 3.29 (AB spin system, 2 H,
C6H2CH2C6H2, J = 12.9), 4.39 and 3.23 (AB spin system, 2 H,
C6H2CH2C6H2, J = 13.1), 4.15 and 4.03 (AB spin system, 2 H,
OCHAHBCONHR, J = 14.2), 3.96 and 2.92 (AB spin system, 4
H, C6H2CH2C6H2, J = 12.5), 3.55 and 2.52 (AB spin system, 4
H, C6H2CH2C6H2, J = 12.5), 3.45 and 3.17 (AB spin system, 2
H, OCHAHBCONHR, J = 16.2), 1.41 and 1.37 (2s, 18 H, 2 But),
᎐
1
᎐
ν(C᎐N) 2224m. NMR (CDCl ): H, δ 7.94–7.90 and 7.51–7.50
᎐
3
(20 H, PPh2), 6.99 (s, 4 H, m-H), 6.52 (s, 4 H, m-H), 6.09 [s with
platinum satellites, 4 H, OCH2PPh2, J(HPt) = 24], 4.45 and 3.05
2
(AB spin system, 8 H, C6H2CH2C6H2, J = 13.4), 4.12 (s, 4 H,
OCH2CONEt2), 3.37 (q, 4 H, NCH2CH3, 3J = 7.0), 3.03 (q, 4 H,
NCH2CH3, 3J = 7.0), 1.30 (s, 18 H, But), 1.16 (t, 6 H,
NCH2CH3, 3J = 7.0), 1.12 (t, 6 H, NCH2CH3, 3J = 7.0) and
0.78 (s, 18 H, But); 13C-{1H}, δ 166.52 (s, C᎐O), 152.26–124.81
᎐
(aromatic C), 112.83 [m, CN and/or C(CN)2], 72.10 [d, OCH2-
PPh2, J(PC) = 38], 71.71 (s, OCH2CONEt2), 40.54 and 39.99 (s,
NCH2CH3), 33.74 and 33.56 [2s, C(CH3)3], 31.39 and 30.88 [2s,
C(CH3)3], 30.47 (2s, C6H2CH2C6H2), 14.08 and 12.83 (2s, NCH2-
CH3); 31P-{1H}, δ 11.9 [s, with platinum satellites, PPh2, J(PPt) =
3621 Hz] (Found: C, 64.12; H, 5.66; N, 5.28. C88H100 N6O6P2Ptؒ
0.75 CH2Cl2 requires C, 64.25; H, 6.15; N, 5.05%).
3
1.10 (d, 3 H, NHCHCH3Ph, J = 6.8 Hz), 0.84 and 0.80 (2s, 18
H, 2 But); the second Me(amide) group overlaps the But signals
at 1.4. 13C-{1H} NMR (CD Cl ): δ 172.70 (s, C᎐O), 168.11 (s,
᎐
2
2
C᎐O), 155.72–125.44 (aromatic C), 75.75 (s, OCH CONHR),
᎐
2
73.35 [centre of a pseudo-q, OCH2PPh2, |J(PC) ϩ 3J(PtransC)|
≈ 46 Hz), 69.87 (s, OCH2CONHR), 50.69 (s, NHCHMePh),
48.89 (s, NHCHMePh), 34.52 [s, C(CH3)3], 34.00 [s, C(CH3)3],
32.13 (s, C6H2CH2C6H2), 31.84 [2 C(CH3)3], 31.47 (s, C6H2-
CH2C6H2), 31.32 and 31.17 [2s, C(CH3)3], 30.95 (s, C6H2-
CH2C6H2), 30.85 (s, C6H2CH2C6H2), 22.54 (s, NHCHCH3Ph)
and 21.69 (s, NHCHCH3Ph). 31P-{1H} NMR (CDCl3): δ 20.70
and 14.26 [ABX spin system with X = Rh, J(AB) = 331,
J(RhA) = 132, J(RhB) = 132 Hz]. FAB mass spectrum: m/z (%)
1498 (18), [M Ϫ BF4]ϩ (expected isotopic profile), 1470 (100),
[M Ϫ CO Ϫ BF4]ϩ (Found: C, 68.16; H, 6.01; N, 1.56.
C91H100BF4N2O7P2Rhؒ0.5 CH2Cl2 requires C, 68.21; H, 6.30; N,
1.74%).
trans-P,PЈ-Carbonyl{5,11,17,23-tetra-tert-butyl-25-(diethyl-
carbamoylmethoxy)-27-(diethylcarbamoyl-êO-methoxy)-26,28-
bis(diphenylphosphinomethoxy)calix[4]arene}rhodium(I) tetra-
fluoroborate 13. A solution of AgBF4 (0.023 g, 0.118 mmol) in
thf (1 cm3) was added to a stirred solution of [{Rh(CO)2Cl}2]
(0.023 g, 0.059 mmol) in CH2Cl2 (5 cm3). Stirring was stopped
after 5 min. The suspension containing AgCl was carefully fil-
tered through Celite and the filtrate added to a solution of L1
(0.150 g, 0.118 mmol) in CH2Cl2 (20 cm3). After standing for 0.5
h the solution was concentrated to ca. 5 cm3. Addition of pen-
tane afforded a yellow precipitate (0.150 g, 83%), m.p. 199 ЊC
(slow decomp.). IR (KBr, cmϪ1): ν(C᎐O) 1989s, ν(C᎐O) 1657m
᎐
᎐
᎐
and 1611s, ν(B᎐F ) 1055. NMR (CDCl3): 1H, δ 7.94–7.31 (20 H,
4
PPh2), 7.25 and 7.17 (AB spin system, 4 H, m-H, J = 2), 6.53
and 6.49 (2s, 4 H, m-H), 5.98 and 5.11 [ABXXЈ spin system
with X,XЈ = P, 4 H, OCH2PPh2, 2J(AB) = 12.8, |J(AX) ϩ
J(AXЈ)| = 12.8, J(BX) not determined], 4.89 and 3.37 (AB spin
Crystallography
Suitable yellow crystals of complex 12ؒ3CHCl3ؒH2O were
obtained by slow diffusion of hexane into a solution of 12 in
CHCl3 at room temperature. Complex 12 crystallizes in the
monoclinic system, space group P21/c, with Z = 4. The unit-cell
parameters were determined, refined (using 25 high-angle
reflections) and data were collected on a Nonius MACH3 dif-
fractometer at 293 K using graphite-monochromated Mo-Kα
radiation, λ = 0.710 73 Å. The data collection [ω–2θ scan type,
2θmax = 52Њ, ±h ϩk ϩl, intensity controls without appreciable
decay (0.2%)] gave 20 483 reflections from which 12 592 were
unique with I > 3σ(I). Crystallographic data are summarized in
Table 2.
After Lorentz-polarization and absorption (transmission fac-
tors derived from the ψ scans of four reflections) corrections,
the structure was solved by direct methods. After refinement of
the heavy atoms, a Fourier-difference map revealed maxima of
residual electron density close to the positions expected for
hydrogen atoms; they were introduced into structure-factor
calculations by their computed coordinates (C᎐H 0.95 Å) and
isotropic thermal parameters such as B(H) = 1.3 Beq(C) Å but
not refined. Solvent hydrogen atoms were omitted. One of the
chlorine atoms of a solvent molecule [Cl(6)] is disordered over
two sites with an occupancy ratio of 1:1. Full-matrix least-
squares refinements on F, σ2(F 2) = σ2 (counts) ϩ (pI )2. A final
2
system, 4 H, C6H2CH2C6H2, J = 12.8), 4.37 (s, 2 H, OCH2-
CONEt2), 3.81 and 2.67 (AB system, 4 H, C6H2CH2C6H2,
2J = 11.8), 3.60 (q, 2 H, NCH2CH3, 3J = 7), 3.26 (s, 2 H, OCH2-
3
CONEt2), 3.11 (q, 2 H, NCH2CH3, J = 7), 2.90 (m, 4 H, two
3
NCH2CH3, J = 7), 1.39 (s, 18 H, But), 1.36 and 1.34 (2t, 6 H,
two NCH2CH3, 3J = 7), 0.82 (s, 9 H, But), 0.81 (s, 9 H, But), 0.74
3
and 0.70 (2t, 6 H, two NCH2CH3, J = 7); 13C-{1H}, δ 170.28
and 167.37 (2s, C᎐O), 155.39–125.12 (aromatic C), 72.99 (t,
᎐
OCH2PPh2, |J(PC) ϩ 3J(PЈC)| = 43), 72.38 and 69.63 (2s,
OCH2CONEt2), 40.74, 40.09, 39.95 and 39.66 (4s, NCH2CH3),
34.14 and 33.59 [2s, C(CH3)3], 31.64, 31.06 and 30.84 [3s,
C(CH3)3], 30.47 (s, C6H2CH2C6H2), 13.82, 12.86, 12.64 and
12.54 (4s, NCH2CH3); 31P-{1H}, δ 18.1 [d, PPh2, J(PRh) = 127
Hz]. FAB mass spectrum: m/z (%) 1401.2 (20), [M Ϫ BF4]ϩ
(expected isotopic profile); 1373.2 (100), [M Ϫ BF4 Ϫ CO]ϩ
(Found: C, 66.20; H, 6.60; N, 1.87. C83H100BF4N2O7P2Rhؒ0.25
CH2Cl2 requires C, 66.19; H, 6.71; N, 1.85%).
trans-P,PЈ-(R,R)-Carbonyl{5,11,17,23-tetra-tert-butyl-25-
[(1-phenylethyl)carbamoylmethoxy]-27-[(1-phenylethyl)-
carbamoyl-êO-methoxy]-26,28-bis(diphenylphosphinomethoxy)-
calix[4]arene}rhodium(I) tetrafluoroborate 14. A solution of
AgBF4 (0.021 g, 0.054 mmol) in thf (1 cm3) was added to a
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402
2401

View Article Online
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Table 2 Crystallographic data for complex 12ؒ3CHCl3ؒH2O
Formula
M
a/Å
b/Å
c/Å
C88H100N6O6P2Ptؒ3CHCl3ؒH2O
1971.0
16.900(5)
16.445(4)
34.436(10)
98.12(2)
9474.7(7)
1.382
18.372
2–26
0.051
β/Њ
U/Å3
Dc/g cmϪ3
µ/cmϪ1
θ Range/Њ
R a
RЈb
0.074
¹
a
R = Σ(||Fo| Ϫ |Fc||)/Σ|Fo|. b RЈ = [Σw(|Fo| Ϫ |Fc|)2/Σw|Fo|2]²; wϪ1 = σ2(Fo).
27 C. Loeber, D. Matt, A. De Cian and J. Fischer, J. Organomet.
Chem., 1994, 475, 297.
28 C. Loeber, C. Wieser, D. Matt, A. De Cian, J. Fischer and
L. Toupet, Bull. Soc. Chim. Fr., 1994, 132, 166.
29 W. Xu, R. J. Puddephatt, L. Manojlovic-Muir, K. W. Muir and
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30 H. Iki, T. Kikuchi, H. Tsuzuki and S. Shinkai, J. Incl. Phenom.,
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33 I. Neda, H.-J. Plinta, R. Sonnenburg, A. Fischer, P. G. Jones and
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35 E. Solari, W. Lesueur, A. Klose, K. Schenk, C. Floriani,
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36 B. R. Cameron and S. J. Loeb, Chem. Commun., 1996, 2003.
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difference map revealed no significant maxima; the highest
peak was at 0.8 Å from the platinum site. Atomic scattering
factors were taken from ref. 57. All calculations were performed
on a DEC Alpha 3100 computer using the MOLEN 58 package.
Fig. 1 was drawn using the MolView program.59
Atomic coordinates, thermal parameters, and bond lengths
and angles have been deposited at the Cambridge Crystallo-
graphic Data Centre (CCDC). See Instructions for Authors,
J. Chem. Soc., Dalton Trans., 1997, Issue 1. Any request to the
CCDC for this material should quote the full literature citation
and the reference number 186/556.
Acknowledgements
38 C. Wieser, D. Matt, L. Toupet, H. Bourgeois and J.-P. Kintzinger,
J. Chem. Soc., Dalton Trans., 1996, 4041.
39 M. G. Gardiner, G. A. Koutsantonis, S. M. Lawrence, P. J. Nichols
and C. L. Raston, Chem. Commun., 1996, 2035.
We are grateful to Dr. P. Braunstein for his interest in this work.
We thank Johnson Matthey plc for a generous loan of platinum
metals.
40 The Chemistry of Organophosphorus Compounds, ed. F. R. Hartley,
Wiley, Chichester, 1990, vol. 1.
41 C. Jaime, J. de Mendoza, P. Prados, P. M. Nieto and C. Sánchez,
J. Org. Chem., 1991, 56, 3372.
42 D. K. Johnson, P. S. Pregosin and L. M. Venanzi, Helv. Chim. Acta,
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Received 20th March 1997; Paper 7/01954H
2402
J. Chem. Soc., Dalton Trans., 1997, Pages 2391–2402