A structural probe for organogold(I) rings and [2]catenanes

Article abstract of DOI:10.1021/om0601706

The digold(I) diacetylides [4-RC₆H₉(4-C ₆H₄OCH₂C≡CAu)₂], which contain a cyclohexylidene hinge group 4-RC₆H₉ with R = H or t-Bu, react with diphosphine ligands Ph₂PZPPh₂ to give the corresponding macrocycles or [2]catenanes [{4-RC₆H ₉(4-C₆H₄OCH₂C≡CAu) ₂(μ-Ph₂PZPPh₂)}_y] [Z = C≡C, (CH₂)₂, (CH₂)₃, or (CH ₂)₄; y = 1, 2, or 4]. When R = t-Bu, the bulky tert-butyl group locks the cyclohexane ring conformation and so provides a good NMR spectroscopic probe of the structure. The organogold(I) [2]catenane complexes are chiral when R = t-Bu, and the complex with Z = (CH₂)₄ gives an equilibrium in solution between ring, double-ring, and [2]catenane. When R = H and Z = (CH₂)₃, the variable-temperature NMR spectra give new insight into the fluxionality in the [2]catenane complex, and when R = H and Z = (CH₂)₄, it is shown that the complex exists in solution as the ring structure, although it crystallizes as a doubly braided [2]catenane.

Full text of DOI:10.1021/om0601706

Organometallics 2006, 25, 2921-2928
2921
Articles
A Structural Probe for Organogold(I) Rings and [2]Catenanes
Nicolle C. Habermehl, Dana J. Eisler, Christopher W. Kirby, Nancy L.-S. Yue, and
Richard J. Puddephatt*
Department of Chemistry, UniVersity of Western Ontario, London, Ontario, N6A 5B7, Canada
ReceiVed February 21, 2006
The digold(I) diacetylides [4-RC6H9(4-C6H4OCH2CtCAu)2], which contain a cyclohexylidene hinge
group 4-RC6H9 with R ) H or t-Bu, react with diphosphine ligands Ph2PZPPh2 to give the corresponding
macrocycles or [2]catenanes [{4-RC6H9(4-C6H4OCH2CtCAu)2(µ-Ph2PZPPh2)}y] [Z ) CtC, (CH2)2,
(CH2)3, or (CH2)4; y ) 1, 2, or 4]. When R ) t-Bu, the bulky tert-butyl group locks the cyclohexane ring
conformation and so provides a good NMR spectroscopic probe of the structure. The organogold(I) [2]-
catenane complexes are chiral when R ) t-Bu, and the complex with Z ) (CH2)4 gives an equilibrium
in solution between ring, double-ring, and [2]catenane. When R ) H and Z ) (CH2)3, the variable-
temperature NMR spectra give new insight into the fluxionality in the [2]catenane complex, and when
R ) H and Z ) (CH2)4, it is shown that the complex exists in solution as the ring structure, although it
crystallizes as a doubly braided [2]catenane.
catenane; typically X ) CR2, Z ) (CH2)n with n ) 3-5),
illustrated in Scheme 1.1,4-9 The structures of many of these
compounds in the solid state have been determined crystallo-
graphically, and some of the factors influencing formation of
the [2]catenane over the macrocycle have been identified.9 In
particular, it has been shown that the [2]catenanes are most
favored for the compounds with diacetylides having the hinge
groups X ) CRR′ (R, R′ ) H, alkyl) and with diphosphines
Ph2PZPPh2 with the spacer group Z ) (CH2)3 and (CH2)4. The
presence of secondary bonding interactions between the inter-
locked macrocycles, especially the presence of aurophilic
attractions with distances Au‚‚‚Au ) 2.5-3.3 Å, can overcome
unfavorable entropy associated with formation of the [2]-
catenanes in solution.4-9
Introduction
In the vibrant field of chemistry of inorganic and organo-
metallic catenanes,1-3 gold(I) compounds have a special position
arising from the easy and reversible formation of catenanes by
self-assembly.1,4-9 Of the organometallic [2]catenanes, the
largest known group is found in the family of organogold(I)
rings and [2]catenanes of general formula [{X(4-C6H4OCH2Ct
CAu)2(µ-Ph2PZPPh2)}y] (y ) 1 for ring complex; y ) 2 for
singly braided [2]catenane; y ) 4 for doubly braided [2]-
* To whom correspondence should be addressed. E-mail: pudd@uwo.ca.
(1) (a) Mingos, D. M. P.; Yau, J.; Menzer, S.; Williams, D. J. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1894. (b) Chui, S. S. Y.; Ng, M. F. Y.;
Che, C.-M. Chem. Eur. J. 2005, 11, 1739.
(2) (a) Wiseman, M. R.; Marsh, P. A.; Bishop, P. T.; Brisdon, B. J.;
Mahon, M. F. J. Am. Chem. Soc. 2000, 122, 12598. (b) Wong, W. W. H.;
Cookson, J.; Evans, E. A. L.; McInnes, E. J. L.; Wolowska, J.; Maher, J.
P.; Bishop, P.; Beer, P. D. Chem. Commun. 2005, 2214.
(3) (a) Fuller, A.-M. L.; Leigh, D. A.; Lusby, P. J.; Slawin, A. M. Z.;
Walker, D. B. J. Am. Chem. Soc. 2005, 127, 12612. (b) Burchell, T. J.;
Eisler, D. J.; Puddephatt, R. J. Dalton Trans. 2005, 268. (c) Hori, A.;
Kataoka, H.; Akasaka, A.; Okano, T.; Fujita, M. J. Polym. Sci. A 2003, 41,
3478. (d) Dietrich-Buchecker, C.; Colasson, B.; Fujita, M.; Hori, A.; Geum,
N.; Sakamoto, S.; Yamaguchi, K.; Sauvage, J.-P. J. Am. Chem. Soc. 2003,
125, 5717. (e) Hori, A.; Akasaka, A.; Biradha, K.; Sakamoto, S.; Yamaguchi,
K.; Fujita, M. Angew. Chem., Int. Ed. 2002, 41, 3269. (f) Hori, A.;
Kumazawa, K.; Kusukawa, T.; Chand, D. K.; Fujita, M.; Sakamoto, S.;
Yamaguchi, K. Chem. Eur. J. 2001, 7, 4142. (g) Fujita, M.; Ogura, K.
Coord. Chem. ReV. 1996, 148, 249.
(4) McArdle, C. P.; Irwin, M. J.; Jennings, M. C.; Puddephatt, R. J.
Angew. Chem., Int. Ed. 1999, 38, 3376.
(5) (a) McArdle, C. P.; Vittal, J. J.; Puddephatt, R. J. Angew. Chem.,
Int. Ed. 2000, 39, 3819. (b) McArdle, C. P.; Jennings, M. C.; Vittal, J. J.;
Puddephatt, R. J. Chem. Eur. J. 2001, 7, 3572.
(6) McArdle, C. P.; Van, S.; Jennings, M. C.; Puddephatt, R. J. J. Am.
Chem. Soc. 2002, 124, 3959.
(7) McArdle, C. P.; Irwin, M. J.; Jennings, M. C.; Vittal, J. J.; Puddephatt,
R. J. Chem. Eur. J. 2002, 8, 723.
One of the most interesting complexes is the doubly braided
[2]catenane (Scheme 1) identified crystallographically for the
case with X ) cyclohexylidene, C6H10, and Z ) (CH2)4.5 The
compound was formed by self-assembly of four digold(I)
diacetylide units with four diphosphine ligands to give two
interlocked 50-membered rings. The structure (Scheme 1)
showed that two of the four gold atoms in each ring were
involved in aurophilic interactions, and so nonequivalent
resonances would be expected in the NMR spectra for the
phosphorus atoms and for the alkynyl units bound to the two
1
types of gold atoms. The H and 31P NMR spectra at low
temperature showed the expected features, but at room tem-
perature, single sets of resonances were observed. It was
suggested that the structure of the doubly braided catenane was
maintained in solution but that easy fluxionality, involving a
rocking motion of the intertwined rings with respect to each
other, could lead to exchange between the nonequivalent gold
atoms and their ligands. The activation energy for the two-site
exchange was determined to be ∆Gq ) 41((1) kJ mol-1.5 The
double-ring complex (Scheme 1) has not been crystallized,
except as a component of the doubly braided [2]catenane,5 but
(8) (a) Mohr, F.; Eisler, D. J.; McArdle, C. P.; Atieh, K.; Jennings, M.
C.; Puddephatt, R. J. J. Organomet. Chem. 2003, 670, 27. (b) Mohr, F.;
Jennings, M. C.; Puddephatt, R. J. Eur. J. Inorg. Chem. 2003, 217.
(9) Habermehl, N. C.; Jennings, M. C.; McArdle, C. P.; Mohr, F.;
Puddephatt, R. J. Organometallics 2005, 24, 5004.
10.1021/om0601706 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 05/09/2006

2922 Organometallics, Vol. 25, No. 12, 2006
Habermehl et al.
Scheme 1a
Chart 1
and provides a particularly useful probe for structure determi-
nation of the gold(I) complexes in solution by NMR.12,13
Results and Discussion
Condensation of 4-tert-butylcyclohexanone with 2 equiv of
phenol gave a new route to the bis(phenol) 4-t-BuC6H9(4-C6H4-
OH)2.12 Reaction of 4-RC6H9(4-C6H4OH)2 [R ) H or t-Bu] with
propargyl bromide in the presence of base then gave the
corresponding dipropargyl derivatives 4-RC6H9(4-C6H4OCH2Ct
CH)2, 1a, R ) H;5 1b, R ) t-Bu. The 1H and 13C NMR spectra
of the new derivative 1b showed two sets of resonances
corresponding to the axial and equatorial 4-C6H4OCH2CtCH
substituents of the cyclohexane ring (Chart 1).12 It is well known
that the bulky tert-butyl group causes the population of the
cyclohexyl conformer with an equatorial tert-butyl group to be
much greater than the one with an axial tert-butyl group and
that this leads to distinctive axial and equatorial resonances.13
The resonances corresponding to the axial (ax) and equatorial
(eq) groups in 1b were assigned on the basis of the 2D correlated
1H-1H (gCOSY) and 1H-13C (gHSQC) NMR spectra and from
1
known trends in the H NMR chemical shifts and coupling
constants in other tert-butylcyclohexyl derivatives.13 In the
related cyclohexylidene derivative C6H10(4-C6H4OCH2CtCH)2,
1a, the axial and equatorial 4-C6H4OCH2CtCH substituents
of the cyclohexane ring are equivalent in the NMR spectra at
room temperature as a result of the easy inversion of the
cyclohexane chair conformation.5
The polymeric digold(I) diacetylide complexes [{4-RC6H9(4-
C6H4OCH2CtCAu)2}n], 2a, R ) H;5 2b, R ) t-Bu, were
prepared by reaction of the corresponding diacetylene 1a or 1b
with 2 equiv of chloro(dimethyl sulfide)gold(I) in the presence
of base. The new complex 2b was insoluble in common organic
solvents and was characterized by elemental analysis and IR
spectroscopy. The IR spectrum of 2b gave a CtC stretching
frequency of 2006 cm-1, considerably lower than the corre-
sponding value for 1b [ν(CC)) 2122 cm-1], as expected for
complexes of this type.1,5
a P ) PPh2, X ) O, S, Co, CH2, CHR, CR2, cyclohexylidene; Z )
(CH2)n, with n ) 2-6.
it has been identified in solution by NMR studies.7 In addition,
examples of the double-ring complexes are known with more
rigid diacetylide ligands as well as in the cationic complex [Au4-
{µ-Ph2P(CH2)4PPh2}2{µ-1,2-C6H4(NHCO-4-C5H4N)2}]4+ 10,11
.
Recently, it was shown that a solution prepared from a
mixture of catenanes [{X(4-C6H4OCH2CtCAu)2(µ-Ph2PZ-
PPh2)}2] and [{X′(4-C6H4OCH2CtCAu)2(µ-Ph2PZPPh2)}2] (for
example, with X ) CH2 and X′ ) CMe2) formed an equilibrium
mixture of the parent catenanes, the mixed ligand catenane [{X-
(4-C6H4OCH2CtCAu)2(µ-Ph2PZPPh2)}{X′(4-C6H4OCH2Ct
CAu)2(µ-Ph2PZPPh2)}], and the ring complexes [X(4-C6H4-
OCH2CtCAu)2(µ-Ph2PZPPh2)] and [X′(4-C6H4OCH2CtCAu)2-
(µ-Ph2PZPPh2)], provided that Z ) (CH2)3.9 However, no such
equilibrium was present when Z ) (CH2)4, and it was deduced
that the complexes existed in solution almost entirely as the
simple ring complexes, even though they may crystallize as the
pure [2]catenanes.9 This finding prompted a new investigation
of the doubly braided catenane complex with X ) C6H10 and
Z ) (CH2)4 to see if it too might dissociate to a ring or double-
ring complex in solution. As part of this study, the related gold-
(I) complexes bearing the 4-tert-butylcyclohexylidene hinge
group (X ) 4-t-BuC6H9) have been prepared. The tert-butyl
substituent controls the conformation of the cyclohexyl group
Reaction of the digold(I) diacetylide oligomers 2a and 2b
with diphosphine ligands Ph2PZPPh2 gave the gold(I) complexes
[{4-RC6H9(4-C6H4OCH2CtCAu)2(µ-Ph2PZPPh2)}y], 3a, R )
H, Z ) CtC; 3b, R ) t-Bu, Z ) CtC; 4a, R ) H, Z ) (CH2)2;
4b, R ) t-Bu, Z ) (CH2)2; 5a, R ) H, Z ) (CH2)3; 5b, R )
t-Bu, Z ) (CH2)3; the known complex 6a, R ) H, Z ) (CH2)4;5
6b, R ) t-Bu, Z ) (CH2)4. When discussing structures of the
complexes, the double-ring, [2]catenane, and doubly braided
$
[2]catenane isomers (Scheme 1) will be designated by , *, or
**, respectively. Thus isomer 3b is the simple ring complex (y
) 1) with R ) t-Bu, Z ) CtC, 5a* is the [2]catenane (y ) 2)
(12) (a) Liaw, D.-J.; Liaw, B.-Y.; Chen, J.-J. J. Polym. Sci., Part A:
Polym. Chem. 2000, 38, 797. (b) Lee, Y.-H.; Allison, B. D.; Grutzner, J.
B. J. Phys. Chem. 1994, 98, 1783.
(13) (a) Anderson, J. E. Top. Curr. Chem. 1974, 45, 139. (b) Eliel, E.
L.; Wilen, S. H.; Mander, L. N. Stereochemistry of Organic Compounds;
Wiley-Interscience: New York, 1994; Chapter 11.
(10) (a) Hunks, W. J.; Jennings, M. C.; Puddephatt, R. J. Z. Naturforsch.
2004, 59b, 1488. (b) Puddephatt, R. J. Chem. Commun. 1998, 1055.
(11) Burchell, T. J.; Eisler, D. J.; Jennings, M. C.; Puddephatt, R. J.
Chem. Commun. 2003, 2228.

Structural Probe for Organogold(I) Rings
Organometallics, Vol. 25, No. 12, 2006 2923
Figure 1. View of the structure of the [2]catenane complex 5a*.
Phenyl groups are omitted for clarity. Selected bond distances
(Å): Au(1)-C(11) 1.99(2); Au(1)-P(1) 2.267(4); Au(2)-C(21)
1.95(1); Au(2)-P(2) 2.296(5); Au(3)-C(31) 2.01(1); Au(3)-P(3)
2.274(4); Au(4)-C(41) 1.99(2); Au(4)-P(4) 2.282(5).
Figure 2. View of the structure of a single disorder component of
complex 5a*, including the phenyl groups. Some of the short
contacts involving hydrogen atoms are indicated by dashed lines.
with R ) H, Z ) (CH2)3, and 6a** is the doubly braided [2]-
catenane (y ) 4) with R ) H, Z ) (CH2)4. The complexes
were characterized in the solid state by elemental analysis and
IR spectroscopy, and the structure of 5a* was determined
crystallographically. The structure of complex 6a** was reported
earlier.5 The structures in solution were determined by NMR
spectroscopy. Complex 4b was essentially insoluble in all
common organic solvents, and so characterization in solution
was not possible. Given that related complexes with other hinge
groups X and with Z ) (CH2)2, including complex 4a, are
soluble and exist as the simple ring complexes (y ) 1),4-9 we
tentatively suggest that complex 4b is polymeric in nature (y
) 4).
Molecular Structure of the [2]Catenane Complex 5a*. A
view of the disordered [2]catenane structure of 5a* is shown in
Figure 1. The diphosphine-digold(I) units are not disordered,
but there is disorder in the diacetylide units. There are two short
Au‚‚‚Au contacts with Au(1)‚‚‚Au(3) ) 3.293(1) Å and Au-
(2)‚‚‚Au(4) ) 3.272(1) Å, and so the two component rings are
twisted away from orthogonality to allow these short contacts.
The catenation is similar to that observed in related complexes
with other hinge groups.4-9
The ring diacetylide unit defined by the hinge group atom
C(61) in Figure 1 is ordered except for the cyclohexylidene
group, which exists in both possible chair conformations.
Clearly, inversion of the cyclohexylidene chair conformation
will cause effective exchange of the axial and equatorial 4-C6H4-
OCH2CtCAuPCH2 substituents. The second ring diacetylide
unit, defined by the hinge group atom C(51), is disordered in a
different way, involving twisting of the entire diacetylide unit
but without inversion of the cyclohexylidene chair conformation
(Figure 1). In the disorder components, the axial and equatorial
4-C6H4OCH2CtCAuPCH2 substituents of this diacetylide unit
are therefore not exchanged.
Figure 3. 1H [400 MHz, in the C6H4 and OCH2 regions only] and
31P NMR spectra (162 MHz, 20 °C, CD2Cl2) of the macrocyclic
complex 6b, showing resonances assigned to axial (ax) and
equatorial (eq) substituents. A trace of the double-ring isomer is
indicated by 6b$ in the 31P NMR spectrum.
Ha resonance (Chart 1) in the [2]catenane compared to the
simple macrocyclic complex.
Structures of the Complexes in Solution. 1. Complexes
with the tert-Butylcyclohexylidene Hinge Group. In consider-
ing the structures of the gold(I) compounds as determined by
NMR spectroscopy, it is important to consider the conformation
of the cyclohexane ring and the axial chirality of the [2]-
catenanes. Consider first the complexes 3b-6b with the tert-
butylcyclohexylidene hinge group. The tert-butyl group prefers
to occupy the equatorial position, and this leads to two sets of
resonances in the NMR spectra for the axial and equatorial
4-C6H4OCH2CtCAuPCH2 substituent groups, which are syn
and anti to the tert-butyl group. The spacer group in complex
3b (Z ) CtC) is too short to allow catenation, and based on
previous work with several different hinge groups, the macro-
cyclic structure can be predicted with confidence.8 The spectra
can therefore be used as a benchmark for a macrocyclic
structure. The 31P NMR spectrum of 3b contained two closely
spaced resonances for the axial and equatorial phosphorus atoms
at δ(31P) ) 18.91 and 18.95. Similarly, there were two
resonances for the OCH2 protons at δ(1H) ) 4.73 and 4.79 and
two resonances each for the hydrogen atoms of the C6H4 group,
Ha [δ ) 6.91, 7.01] and Hb [δ ) 7.13, 7.30].
Figure 2 shows the structure of the catenane with phen-
ylphosphorus groups and some of the hydrogen atoms included.
Figure 3 shows the 1H NMR spectrum, in the regions of the
C6H4 and OCH2 resonances, and the 31P NMR spectrum of
complex 6b in CD2Cl2 solution at room temperature. The spectra
are very similar to those for 3b, Z ) CtC, described above,
and indicate that 6b exists primarily as the simple macrocyclic
digold(I) complex in this solution.
1
This figure is useful in understanding the H NMR spectra to
be discussed below. The central CH2 group of the diphosphine
ligand makes short contacts with the gold atoms [Au(1)‚‚‚H(5A)
2.97; Au(2)‚‚‚H(2A) 2.94; Au(3)‚‚‚H(2B) 2.92; Au(4)‚‚‚H(5B)
2.82 Å], but it is not clear if the interactions represent secondary
bonding or if they represent van der Waals contacts arising
through steric congestion. There are several aryl‚‚‚aryl edge-
face or vertex-face interactions that will cause significant
In dilute solution, the macrocyclic complex 6b was the
dominant isomer present in solvent CD2Cl2 (Figure 3), C6D5-
NO2, or CDCl3. However, in more concentrated solution in
1
1
effects on H NMR chemical shifts. Note, for example, the
CDCl3, the H and 31P NMR spectra were more complex and
interaction of C(37)-H with the adjacent phenyl group [H(37A)‚
‚‚C(1A) 3.1; H(37A)‚‚‚C(1D) 3.1; H(37A)‚‚‚C(1E) 2.9; H(37A)‚
‚‚C(1F) 2.8 Å], which will cause a ring shielding effect on this
indicated the presence of two other isomers. Figure 4 shows
the concentration dependence of the 31P NMR spectrum at room
temperature. The ring complex 6b gives only one broad

2924 Organometallics, Vol. 25, No. 12, 2006
Habermehl et al.
Figure 5. Variable-temperature 1H NMR spectra (600 MHz, CDCl3
solution) in the region of the C6H4 protons Ha and Hb (Chart 1):
(a) 60 °C; (b) 25 °C; (c) -25 °C. The peak marked # is due to
CHCl3.
Figure 4. Concentration dependence of the 31P NMR spectrum
(162 MHz) of a mixture of isomers 6b, 6b*, and 6b$: (a) c ) 1.5
× 10-2 M; (b) c ) 3.3 × 10-3 M; (c) c ) 8.3 × 10-4 M.
Concentration c is the total concentration assuming that the complex
was present only as 6b.
Figure 6. Variable-temperature 31P NMR spectra [243 MHz,
CDCl3 solution] of the macrocyclic complex 6b, in equilibrium
with the [2]catenane 6b* and double-ring 6b$ isomers: (a) 60 °C;
(b) 25 °C; (c) 0 °C.
resonance in the more concentrated solution (Figure 4a), as a
result of exchange with the double-ring complex 6b$.7 There
are also two sharp singlet resonances, which are attributed to
the axial and equatorial phosphorus atoms of a [2]catenane
species, which could be 6b* or 6b**. At lower concentrations,
the relative amounts of the higher molecular weight isomers,
the [2]catenane 6b* or 6b** and the double-ring complex 6b$,
decrease with respect to the simple ring complex 6b and the
expected two singlets for 6b are resolved, as the rate of exchange
with 6b$ decreases (Figures 4b and 4c). The relative molecular
weights of individual components can be estimated from their
relative concentrations as a function of the total concentration
(a greater concentration dependence is expected for the “tet-
ramer” doubly braided [2]catenane, with K(eq) ) [6b**]/[6b],4
than for either “dimer” catenane or double ring). The integration
of the 31P NMR spectra in CDCl3 solution at 293 K was
complicated by variation in peak widths as a function of
concentration (Figure 4), but they are accurate enough to show
that the catenane is 6b*, formed by 2+2 self-assembly, rather
than 6b**, formed by 4+4 self-assembly. Integration as a
function of concentration at 293 K gave K(eq) ) [6b$]/[6b]2 )
21(2) L mol-1 for equilibration of 6b to give 6b$, K(eq) ) [6b*]/
[6b]2 ) 8(3) L mol-1 for equilibration of 6b to give 6b*, and
K(eq) ) [6b*]/[6b$] ) 0.4(2) for equilibration of 6b$ to give
6b*.
coalesced [δ(H) ) 4.75, 4.80], but at -25 °C separate
resonances are observed [6b: δ(H) ) 4.78, 4.85; 6b$: δ(H) )
4.67, 4.80].
Figure 6 shows the variable-temperature 31P NMR spectra.
Coalescence of the resonances of 6b and 6b$ is observed at 60
°C (Figure 6a), but the chemical exchange is slowed at low
temperatures, and the expected two resonances for the axial and
equatorial phosphorus atoms of 6b are resolved and observed
at -25 °C (Figure 6c). However, only a single broad resonance
is observed for 6b$ even at low temperature (Figure 6c). By
integration of the resonances for 6b and 6b$ over the temperature
range from 0 to -50 °C, when separate resonances were well
resolved, the thermodynamic parameters for equilibration of 6b
to give 6b$ were found to be ∆H ) -11(1) kJ mol-1 and ∆S
) -14(2) J K-1 mol-1. It was not possible to obtain thermo-
dynamic parameters for formation of 6b* because reliable
integration of the broad peaks at low temperatures was not
possible.
To study the relative sizes of the molecules, the 31P DOSY
spectrum [243 MHz, relaxation delay 2.5 s, 0 °C, CDCl3
solution] of an equilibrium mixture of 6b, 6b*, and 6b$ was
recorded (Figure 7).14 The spectrum shows that the diffusion
rates follow the sequence 6b* > 6b > 6b$, whereas, on the
basis of the relative molecular weights only, the sequence 6b
> 6b* ) 6b$ would be expected. We suggest that lower
solvation of the roughly spherical molecule 6b* compared to
the more open molecules 6b and 6b$ might account for the
difference. A similar difference in relative diffusion rates for
the macrocycles [{PdCl2(Ph2P(CH2)12PPh2)}n], n ) 1 and 2,
has been reported as for 6b and 6b$, but the technique does not
appear to have been used previously in studies of catenation.14a
Figure 5 shows the variable-temperature 1H NMR spectra of
6b in the region of the C6H4 resonances. At 60 °C (Figure 5a),
the resonances of the complexes 6b and 6b$ are coalesced [δ-
(Ha) ) 6.92, 6.99; δ(Hb) ) 7.05, 7.23 (overlapped with the peak
due to CHCl3)], but the resonances of the [2]catenane 6b* [δ-
(Ha) ) 6.28, 6.44; δ(Hb) ) 6.67, 6.70] are separate and
characteristically shielded compared to the macrocycle 6b. At
-25 °C (Figure 5c), the resonances of the complexes 6b [δ-
(Ha) ) 6.98, 7.02; δ(Hb) ) 7.14, 7.24] and 6b$ [δ(Ha) ) 6.80,
6.90; δ(Hb) ) 7.03, 7.22] are separate, as a result of slower
exchange, but the resonances for the two complexes have similar
chemical shifts. A similar effect was observed in the region of
the OCH2 protons. At 60 °C, the resonances for 6b and 6b$ are
(14) (a) Paulusse, J. M. J.; Sijbesma, R. P. Chem. Commun. 2003, 1494.
(b) Paulusse, J. M. J.; Huijbers, J. P. J.; Sijbesma, R. P. Macromolecules
2005, 38, 6290. (c) Johnson, C. S. Prog. Nucl. Magn. Res. Spectrosc. 1999,
34, 203.

Structural Probe for Organogold(I) Rings
Organometallics, Vol. 25, No. 12, 2006 2925
Figure 7. 31P DOSY spectrum [243 MHz, relaxation delay 2.5 s,
0 °C, CDCl3 solution] of an equilibrium mixture of 6b, 6b*, and
6b$. RDR ) relative diffusion rate.
Figure 9. 31P NMR spectrum [162 MHz, CDCl3 solution] of a
mixture of isomers 5b and 5b*.
2. Complexes with the Cyclohexylidene Hinge Group. The
NMR spectra of the complexes with the cyclohexylidene hinge
group are simpler at room temperature but either similar or more
complex compared to the tert-butylcyclohexylidene derivatives
at low temperature. Figure 10 shows the 31P NMR spectra of
an equilibrium mixture of 5a, 5a*, and an uncharacterized
oligomeric isomer 5a#. At room temperature, the resonance of
the macrocyclic complex 5a is broad as a result of exchange
with 5a#, but it is seen as a sharp singlet at -40 °C as this
exchange process is slowed. At lower temperatures, the reso-
nance again becomes broad and finally splits to give two
resonances (Figure 10). These resonances correspond to the axial
and equatorial phosphorus atoms, and they become effectively
equivalent at higher temperatures as a result of inversion of the
cyclohexylidene group (eq 1). On the basis of the coalescence
Figure 8. 1H NMR spectra [400 MHz, 25 °C] of an equilibrium
mixture of the macrocyclic complex 5b (O) and the [2]catenane
5b* (b) showing resonances assigned to axial (ax) and equatorial
(eq) C6H4 and OCH2 substituents: (a) spectrum in concentrated
solution in CDCl3, when the [2]catenane 5b* is dominant (peak
labeled * is due to CHCl3); (b) spectrum in more dilute solution in
CD2Cl2, when 5b is dominant.
Chart 2
Figure 8 shows the 1H and 31P NMR spectra of an equilibrium
mixture of the ring complex 5b and the [2]catenane complex
5b* in CDCl3 and in CD2Cl2. In both solvents, the axial and
equatorial resonances for C6H4 and OCH2 are easily observed
1
in the H NMR spectra. The characteristic marked shift of the
temperature of -70 °C, the activation energy for inversion of
C6H4 resonances of the [2]catenane 5b* with respect to the
macrocycle 5b is clearly seen in Figure 8 and arises from the
aryl‚‚‚aryl interactions (Figure 2).4-9 It should be noted that
the [2]catenane 5b* exhibits axial chirality as a result of the
presence of the tert-butylcyclohexylidene hinge groups.9 The
[2]catenane is expected to have effective C2 symmetry (Chart
2), whereas the macrocycle has Cs symmetry. This change in
symmetry on catenation does not change the expected number
of C6H4 or 31P resonances, but it does lead to a very broad ill-
resolved resonance for the OCH2 protons in the 1H NMR spectra
(Figure 8).
the cyclohexylidene ring is estimated to be 42.6(1.0) kJ mol-1
,
which is very similar to the known activation energy for
inversion of cyclohexane of ∆Gq ) 43.1-43.9 kJ mol-1
(measured for cyclohexane-d11 in CS2) with a coalescence
temperature of Tc ) -61 °C.15 As expected, the equilibrium
between the macrocycle 5a and oligomeric isomer 5a# favors
5a# at lower temperatures (Figure 10), and it is clear, by
comparing Figures 7 and 8, that the oligomeric form is relatively
favored in the complexes with the cyclohexylidene compared
to the tert-butylcyclohexylidene hinge group. The 31P NMR
resonance for the [2]catenane 5a* is also expected to split at
In the 31P NMR spectrum (Figure 9), the axial and equatorial
resonances for the [2]catenane 5b* are resolved and appear as
an “AB” multiplet, but those for the macrocyclic complex 5b
are not resolved.
(15) (a) Anet, F. A. L.; Bourn, A. J. R. J. Am. Chem. Soc. 1967, 89,
760. (b) Bovey, F. A.; Hood, F. P.; Anderson, E. W.; Kornegay, R. L. J.
Chem. Phys. 1964, 41, 2042.

2926 Organometallics, Vol. 25, No. 12, 2006
Habermehl et al.
Scheme 2
Figure 10. Variable-temperature 31P NMR spectra [162 MHz, CD2-
Cl2 solution] of a mixture of isomers 5a, 5a*, and 5a#.
1
Figure 11. Variable-temperature H NMR spectra [400 MHz] of
a mixture of macrocyclic complex 5a and [2]catenane complex 5a*
in CD2Cl2 solution. The peak marked * is due to CHDCl2.
low temperature, but, although the peak clearly becomes broader
at low temperature, the splitting is not fully resolved (Figure
10).
group t-BuC6H9 or Me2C shows the same type of effect in the
low-temperature NMR spectra.
The variable-temperature 1H NMR spectra of the mixture of
isomers 5a, 5a*, and 5a# in the region of the C6H4 groups are
illustrated in Figure 11. The resonances due to the C6H4 groups
of 5a and 5a# are overlapped and so not easily interpreted, but
the spectra of 5a* are mostly resolved and are interesting. At
room temperature, there are only two resonances [δ(Ha) ) 6.11;
δ(Hb) ) 6.77], as expected, because inversion of the cyclo-
hexylidene ring is rapid at this temperature. However, at lower
temperatures, the Ha resonance becomes extremely broad and
finally splits into three broad resonances at δ ) 6.7, 5.8, and
5.1 in a roughly 2:4:2 intensity ratio (Figure 11). The low-
temperature NMR spectrum of 5a* (Figure 11) is more complex
than the room-temperature NMR spectrum of 5b (Figure 8),
which contains only two closely spaced Ha resonances [δ(Ha)
) 6.02, 6.15], corresponding to the axial and equatorial aryl
groups. The low-temperature NMR spectrum of 5a* can be
interpreted in terms of the mechanism of fluxionality shown in
Scheme 2, which is consistent with the solid-state structure
(Figures 1, 2). Thus, inversion of one of the cyclohexylidene
rings leads to formation of a new [2]catenane conformer with
Au‚‚‚Au bonding between Pax-Au‚‚‚Au-Pax and Peq-Au‚‚‚
Au-Peq units rather than between pairs of Peq-Au‚‚‚Au-Pax
units (Scheme 2). The C2-symmetric structure can be attained
either by a second cyclohexylidene inversion or by rotation of
the component macrocycles with respect to one another, in a
process that requires making and breaking of pairs of Au‚‚‚Au
secondary bonds (Scheme 2). The activation energy for the
fluxional process at the coalescence temperature of 233 K is
∆Gq ) 43(1) kJ mol-1. Because this is very similar to the known
activation energy for cyclohexane inversion, it is suggested that
the cyclohexylidene ring inversion is the key step. In support,
we note that neither of the analogous [2]catenanes with the hinge
Conclusions
The NMR criteria established above indicate that the doubly
braided [2]catenane 6a**, with X ) C6H10 and Z ) (CH2)4,
dissociates in solution to form the simple macrocyclic complex
6a. This explains why no mixed ligand catenane is formed on
mixing the complexes with X ) C6H10, Z ) (CH2)4 and with
X ) CMe2, Z ) (CH2)4, since both exist in solution as the
simple macrocycle.9 The activation energy for the fluxional
process of 6a in CD2Cl2 solution at the coalescence temperature
Tc ) -68 °C of ∆Gq ) 41((1) kJ mol-1 is fully consistent
with the cyclohexylidene inversion step, causing coalescence
of axial and equatorial substituents of the macrocycle. It is
remarkable that the very selective crystallization of the doubly
braided [2]catenane complex 6a** occurs from a solution in
which this species cannot be detected by NMR.5 The tetramer-
ization of 6a may occur at the growing crystal surface, although
the possibility that there is a sufficient concentration of 6a**
in solution to allow crystallization cannot be discarded. Dis-
solution of 6a** leads to very easy dissociation back to 6a, a
process that is largely entropy-driven. The easy, reversible
oligomerization relies on the lability of the Au-P linkages,
which allows facile, reversible ring opening and closing, ring
expansion and contraction, and threading and unthreading
reactions.
Finally, we note that the 4-tert-butylcyclohexylidene hinge
group was introduced so that structure determination of com-
plexes in solution would be simplified compared to the case
with the simpler cyclohexylidene hinge group, when deceptively
simple spectra can be obtained. It was successful in this respect,
but it also affects the position of the equilibrium of self-

Structural Probe for Organogold(I) Rings
Organometallics, Vol. 25, No. 12, 2006 2927
(SMe2)] (0.885 g, 3.0 mmol) in THF (100 mL)/MeOH (50 mL).
The mixture was stirred for 4 h. Then the yellow precipitate was
isolated by filtration, washed with THF, MeOH, and pentane, and
dried under vacuum. Yield: 1.04 g (88%). IR (KBr disk): ν(Ct
C) 2006 cm-1. Anal. Calcd for C28H30Au2O2: C, 42.44; H, 3.82.
Found: C, 42.14; H, 3.55.
assembly. This unexpected phenomenon is most prominent for
complexes 6, for which 6a (R ) H) is always dominant in
solution, whereas 6b (R ) t-Bu) is in equilibrium with both
the double-ring 6b$ and [2]catenane 6b* isomers.
Experimental Section
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H10}(Ph2PCtCPPh2)], 3a.
A mixture of [{C6H10(4-C6H4OCH2CtCAu)2}n], 2a (0.130 g, 0.18
mmol), and Ph2PCtCPPh2 (0.057 g, 0.15 mmol) in CH2Cl2 (10
mL) was stirred at room temperature for 4 h. Decolorizing charcoal
(0.2 g) was added, the mixture was filtered, and the solvent was
evaporated under vacuum to give the product, which was recrystal-
lized from CH2Cl2/pentane. Yield: 68%. Anal. Calcd for C50H42-
Au2O2P2: C, 53.11; H, 3.74. Found: C, 53.02; H, 3.68. IR: ν(Ct
C) 2138 cm-1. NMR in CD2Cl2: δ(1H) 1.48 [m, 4H, Cy-C3H2];
1.53 [m, 2H, Cy-C4H2); 2.22 [m, 4H, Cy-C2H2]; 4.77 [s, 4H, OCH2];
NMR spectra were recorded using a Varian Inova 600 or 400 or
1
a Varian Mercury 400 spectrometer. H and 13C NMR chemical
shifts are reported relative to TMS, and 31P NMR chemical shifts
are reported relative to 85% H3PO4 as an external standard. The
NMR labeling for the diacetylide groups is shown in Chart 1. IR
spectra were recorded as KBr disks or as Nujol mulls between NaCl
plates using a Perkin-Elmer 2000 FT-IR spectrometer. High-
resolution mass spectra were measured by using a Finnigan MAT
8400 spectrometer. [AuCl(SMe2)], C6H10(4-C6H4OCH2CCH)2, 1a,
and [{C6H10(4-C6H4OCH2CCAu)2}n], 2a, were prepared according
to the literature.12,16 Reactions involving gold compounds were
protected from light by use of darkened reaction flasks. Caution:
Some gold acetylides are potentially explosive; they should be
prepared in small quantities and not subjected to shock.
3
3
6.97 [d, 4H, J(HH) ) 9 Hz, C6H4-CHa]; 7.23 [d, 4H, J(HH) )
9 Hz, C6H4-CHb]; 7.4-7.8 [m, 20H, PPh]; δ(31P) 18.94 [s].
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H9-4-t-Bu}(Ph2PCtC-
PPh2)], 3b. A mixture of 2b (0.148 g, 0.187 mmol) and Ph2PCt
CPPh2 (0.058 g, 0.147 mmol) in CH2Cl2 (15 mL) was stirred at
room temperature for 4 h. The mixture was filtered over Celite,
then the volume of the filtrate was reduced to 3 mL at reduced
pressure. Pentane (90 mL) was added to give an off-white solid,
which was isolated by filtration, washed with pentane, and dried
under vacuum. Yield: 0.152 g (86%). IR (KBr disk): ν(CtC) 2121
cm-1. Anal. Calcd for C54H50Au2O2P2: C, 54.65; H, 4.25. Found:
C, 54.19; H, 4.40. NMR in CD2Cl2: δ(1H) 0.75 [s, 9H, CMe3];
1.13-1.19 [m, 3H, Cy-H3-ax + Cy-H4-ax]; 1.67 [m, 2H, Cy-H3-
1,1-Bis(4-hydroxyphenyl)-4-tert-butylcyclohexane. To a solu-
tion of phenol (8.46 g, 0.090 mol) and 4-tert-butylcyclohexanone
(6.90 g, 0.045 mol) in glacial acetic acid (13 mL) was added
concentrated sulfuric acid (6 mL). The reaction mixture was stirred
for 4 days and then poured into water (200 mL) and neutralized by
addition of sodium bicarbonate. The aqueous phase was extracted
with diethyl ether (3 × 75 mL), then the combined organic phases
were washed with a saturated aqueous solution of sodium bicarbon-
ate. The organic phase was dried (MgSO4) and filtered, and the
solvent was removed under reduced pressure to give the crude
product as a dark orange oil. Recrystallization from hot chloroform
gave the pure product as a white crystalline solid, mp 180-181 °C
(lit.12 mp 181-182 °C). Yield: 2.89 g (20%). This compound has
2
eq]; 1.80 [m, 2H, Cy-H2-ax]; 2.71 [d, 2H, J(HH) ) 12 Hz, Cy-
H2-eq]; 4.73 [s, 2H, OCH2-ax]; 4.79 [s, 2H, OCH2-eq]; 6.91 [d,
3
3
2H, J(HH) ) 8 Hz, C6H4-Ha-ax,]; 7.01 [d, 2H, J(HH) ) 8 Hz,
C6H4-Ha-eq,]; 7.13 [d, 2H, J(HH) ) 8 Hz, C6H4-Hb-ax]; 7.30
3
[d, 2H, J(HH) ) 8 Hz, C6H4-Hb-eq]; 7.50 [m, 8H, PPh]; 7.56
3
1
[m, 4H, PPh]; 7.68-7.74 [m, 8H, PPh]; δ(31P) 18.91 [s, P-ax];
18.95 [s, P-eq].
been prepared previously by a different method, and the H and
13C NMR spectra (acetone-d6) have been reported.12
1,1-Bis(4-prop-2-ynyloxyphenylene)-4-tert-butylcyclohex-
ane, 1b. A mixture of 1,1-bis(4-hydroxyphenyl)-4-tert-butylcyclo-
hexane (1.62 g, 5 mmol), potassium carbonate (2.08 g, 15 mmol),
and propargyl bromide (2.7 mL of an 80% solution by weight in
toluene, 24 mmol) in acetone (50 mL) was refluxed for 34 h. Once
cooled, the mixture was filtered to remove insoluble inorganic salts,
then the solvent of the filtrate was removed under reduced pressure.
Water (50 mL) was added, and the aqueous phase was extracted
with dichloromethane (3 × 35 mL). The combined organic phases
were dried (MgSO4) and filtered, and the solvent was removed
under reduced pressure to give a dark yellow viscous liquid, which
was dried under vacuum for 8 h. Yield: 1.21 g (60%). IR (Nujol):
ν(CtC) 2122 cm-1. NMR in CDCl3: δ(1H) 0.77 [s, 9H, CMe3];
1.10-1.23 [m, 3H,Cy H3-ax + H4-ax]; 1.69 [m, 2H, Cy H3-eq];
1.86 [m, 2H, Cy H2-ax]; 2.49 [t, 1H, 4J(HH) ) 2 Hz, CtCH-ax];
2.52 [t, 1H, 4J(HH) ) 2 Hz, CtCH-eq]; 2.65 [m, 2H, H2-eq]; 4.61
[d, 2H, J(HH) ) 2 Hz, OCH2-ax]; 4.67 [d, 2H, J(HH) ) 2 Hz,
OCH2-eq]; 6.81 [d, 2H, 3J(HH) ) 9 Hz, C6H4-Ha-ax]; 6.92 [d, 2H,
3J(HH) ) 9 Hz, C6H4-Ha-eq]; 7.08 [d, 2H, 3J(HH) ) 9 Hz, C6H4-
Hb-ax]; 7.27 [d, 2H, 3J(HH) ) 9 Hz, C6H4-Hb-eq]; δ(13C) ) 23.76
[C3]; 27.47 [CMe3]; 32.33 [CMe3]; 37.65 [C2]; 44.72 [C1]; 48.26
[C4]; 55.70 [OCH2-ax]; 55.79 [OCH2-eq]; 75.29 [CtCH-ax]; 75.32
[CtCH-eq]; 78.80 [CtCH]; 114.17 [C6H4-ax]; 114.52 [C6H4-eq];
127.16 [C6H4-ax]; 128.97 [C6H4-eq]; 138.47 [C4′-ax]; 145.17 [C4′-
eq]; 155.13 [C1′-ax]; 155.22 [C1′-eq]. EI-MS (m/z): calcd for
C28H32O2, 400.2402; found, 400.2390.
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H10}{Ph2P(CH2)2PPh2}], 4a.
This was prepared in a manner similar to that for 3a from 2a and
Ph2P(CH2)2PPh2. Cream solid. Yield: 74%. IR (KBr disk): ν(Ct
C) 2135 cm-1. Anal. Calcd for C50H46Au2O2P2: C, 52.92; H, 4.09.
Found: C, 52.55; H, 4.07. NMR in CD2Cl2: δ(1H) 1.31 [m, 2H,
Cy-C4H2]; 1.48 [m, 4H, Cy-C3H2); 2.25 [m, 8H, Cy-C2H2 + PCH2];
4.75 [s, 4H, OCH2]; 6.98 [d, 4H, 3J(HH) ) 9 Hz, C6H4-Ha]; 7.27
3
[d, 4H, J(HH) ) 9 Hz, C6H4-Hb]; 7.4-7.6 [m, 20H, PPh]; δ-
(31P) 40.29 [s].
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H9-4-t-Bu}{Ph2P(CH2)2-
PPh2}], 4b. A mixture of 2b (0.198 g, 0.250 mmol) and 1,2-bis-
(diphenylphosphino)ethane (0.082 g, 0.206 mmol) in CH2Cl2 (10
mL) was stirred for 3 h. The product was insoluble and was isolated
as an off-white solid. The isolated solid was insoluble in CH2Cl2,
CHCl3, and DMSO. Yield: 0.149 g (60%). IR (KBr disk): ν(Ct
C) 2133 cm-1. Anal. Calcd for C54H54Au2O2P2: C, 54.46; H, 4.57.
Found: C, 54.06; H, 4.41. The complex was insufficiently soluble
to give NMR data.
4
4
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H10}{Ph2P(CH2)3PPh2}], 5a,
and [2]Catenane 5a*. These were prepared in a manner similar
to that for 3a from 2a (0.076 g, 0.096 mmol) and Ph2P(CH2)3-
PPh2. Cream solid. Yield: 0.175 g (89%). IR (KBr disk): ν(Ct
C) 2130 cm-1. Anal. Calcd for C51H48Au2O2P2: C, 53.32; H, 4.21.
Found: C, 53.69; H, 4.08. 5a: NMR in CD2Cl2: δ(1H) 1.30 [m,
2H, Cy-C4H2]; 1.50 [m, 4H, Cy-C3H2); 1.85 [m, 2H, PCH2CH2];
2.23 [m, 4H, Cy-C2H2]; 2.47 [m, 4H, PCH2]; 4.74 [s, 4H, OCH2];
6.97 [d, 4H, 3J(HH) ) 9 Hz, C6H4-Ha]; 7.23 [d, 4H, 3J(HH) ) 9
Hz, C6H4-Hb]; 7.2-7.6 [m, 20H, PPh]; δ(13C) 21.1 [t, J(PC) ) 7
Hz, CH2CH2P]; 22.9 [s, Cy-C4]; 23.4 [s, Cy-C3]; 29.7 [dd, J(PC)
) 16, 35 Hz, CH2P]; 37.5 [s, Cy-C2]; 45.1 [s, Cy-C1]; 56.5 [s,
CH2O]; 97.8 [d, J(PC) ) 28 Hz, CCAu]; 131.6 [d, J(PC) ) 152
[{4-t-BuC6H9(4-C6H4OCH2CtCAu)2}n], 2b. A solution of 1b
(0.602 g, 1.5 mmol) and sodium acetate (0.616 g, 7.5 mmol) in
THF (20 mL)/MeOH (20 mL) was added to a solution of [AuCl-
(16) Brandys, M.-C.; Jennings, M. C.; Puddephatt, R. J. J. Chem. Soc.,
Dalton Trans. 2000, 4601.

2928 Organometallics, Vol. 25, No. 12, 2006
Habermehl et al.
Hz, CCAu]; δ(31P) 35.92 [s]. 5a*: NMR in CD2Cl2: δ(1H) 1.28
[m, 4H, Cy-C4H2]; 1.47 [m, 8H, Cy-C3H2); 1.97 [m, 8H, Cy-C2H2];
2.20 [m, 4H, PCH2CH2]; 2.75 [m, 8H, PCH2]; 4.62 [br s, 8H,
Table 1. Crystal Data and Structure Refinement for
5a*‚3CH2Cl2
formula, fw
T
C
105H102Au4Cl6O4P4, 2552.31
3
OCH2]; 6.11 [d, 8H, J(HH) ) 9 Hz, C6H4-Ha]; 6.77 [d, 8H,
150(2) K
3J(HH) ) 9 Hz, C6H4-Hb]; 7.2-7.5 [m, 40H, PPh]; δ(13C) 19.9
[m, CH2CH2P]; 26.5 [s, Cy-C4]; 26.8 [s, Cy-C3]; 27.8 [dd, J(PC)
) 15, 30 Hz, CH2P]; 37.2 [s, Cy-C2]; 43.8 [s, Cy-C1]; 56.6 [s,
CH2O]; 100.2 [d, J(PC) ) 30 Hz, CCAu]; 131.5 [d, J(PC) ) 152
Hz, CCAu]; δ (31P) 32.17 [s].
wavelength
cryst syst
space group
cell dimens
0.71073 Å
monoclinic
P21/n
a ) 12.2933(11) Å
b ) 48.841(4) Å
c ) 16.6524(16) Å
â ) 96.913(2)°
9925.6(16) Å3
4
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H9-4-t-Bu}{Ph2P(CH2)3-
PPh2}], 5b, and [2]Catenane 5b*. These were prepared in a
manner similar to that for 3b, from 2b (0.076 g, 0.096 mmol) and
Ph2P(CH2)3PPh2 (0.033 g, 0.080 mmol). The product was isolated
as a pale pink solid. Yield: 0.079 g (82%). IR (KBr disk): ν(Ct
C) 2129 cm-1. Anal. Calcd for C55H56Au2O2P2: C, 54.83; H, 4.68.
Found: C, 54.52; H, 4.65. 5b: NMR in CD2Cl2: δ(1H) 0.76 [s,
9H, CMe3]; 1.15 [m, 3H, Cy-H3-ax + Cy-H4-ax]; 1.69 [m, 2H,
Cy-H3-eq]; 1.80 [m, 2H, PCH2CH2]; 1.82 [m, 2H, Cy-H2-ax]; 2.47
[m, 4H, PCH2]; 2.75 [d, 2H, 2J(HH) ) 14 Hz, Cy-H2-eq]; 4.72 [s,
V
Z
d(calc)
abs coeff
no. of indep reflns
abs corr
1.708 Mg m-3
6.170 mm-1
14 596 [R(int) ) 0.0669]
integration
no. of data/restr/params
Goof on F2
R [I > 2σ(I)]
14 596/103/908
0.920
R1 ) 0.0657, wR2 ) 0.1469
[d, 4H, 3J(HH) ) 8 Hz, C6H4-Hb-ax]; 7.20 [d, 4H, 3J(HH) ) 8 Hz,
C6H4-Hb-eq]; δ(31P) 37.75 [br s, P-ax + P-eq].
3
2H, OCH2-ax]; 4.78 [s, 2H, OCH2-eq]; 6.92 [d, 2H, J(HH) ) 9
Hz, C6H4-Ha-ax]; 7.00 [d, 2H, 3J(HH) ) 9 Hz, C6H4-Ha-eq];
7.14 [d, 2H, 3J(HH) ) 9 Hz, C6H4-Hb-ax]; 7.30 [d, 2H, 3J(HH) )
9 Hz, C6H4-Hb-eq]; 7.40-7.58 [m, 20H, PPh]; δ(31P) 36.29 [s].
5b*: NMR in CD2Cl2: δ(1H) 0.65 [s, 18H, CMe3]; 1.15 [m, 6H,
Cy-H3-ax + Cy-H4-ax]; 1.50 [m, 4H, PCH2CH2]; 1.69 [m, 4H, Cy-
H3-eq]; 1.82 [m, 4H, Cy-H2-ax]; 2.56 [m, 8H, PCH2]; 2.75 [d, 2H,
2J(HH) ) 14 Hz, Cy-H2-eq]; 4.58-4.66 [br, 8H, OCH2]; 6.02 [d,
Structure Determination. Crystals of 5a*‚3CH2Cl2 were grown
by slow diffusion of ether into a solution containing a mixture of
isomers 5a, 5a*, and 5a# in CH2Cl2. A thin, colorless plate was
mounted on a glass fiber. Data were collected using a Nonius
Kappa-CCD diffractometer with COLLECT (Nonius B.V., 1998).
The unit cell parameters were calculated and refined from the full
data set. Crystal cell refinement and data reduction were carried
out using DENZO (Nonius B.V., 1998). The data were scaled using
SCALEPACK (Nonius B.V., 1998), and no other absorption
correction was applied. The crystal data and refinement parameters
are listed in Table 1.
The SHELXTL-NT V5.1 (Sheldrick, G. M.) suite of programs
was used to solve the structure by direct methods, followed by
successive difference Fouriers. The hydrogen atom positions were
calculated geometrically and were included as riding on their
respective carbon atoms. There was considerable disorder present
in the structure. One entire (C6H10)(C6H4CH2CtC)2 unit was
disordered over two positions and modeled as a 50:50 isotropic
mixture with geometric restraints applied. The second bridging
cyclohexyl moiety was disordered over two positions and modeled
as a 60:40 isotropic mixture with geometric restraints. The solvent
molecules were poorly ordered and were modeled isotropically with
appropriate occupancies and geometric restraints.
3
3
4H, J(HH) ) 9 Hz, C6H4-Ha-ax]; 6.15 [d, 4H, J(HH) ) 9 Hz,
C6H4-Ha-eq]; 6.73 [d, 4H, 3J(HH) ) 9 Hz, C6H4-Hb-ax]; 6.80 [d,
3
4H, J(HH) ) 9 Hz, C6H4-Hb-eq]; 7.40-7.70 [m, 40H, PPh]; δ-
(31P) 32.50, 32.57 [AB quartet, J(PP) ) 6 Hz].
4
[Au2{(CtCCH2O-4-C6H4)2-1,1-C6H9-4-t-Bu}{Ph2P(CH2)4-
PPh2}], 6b. This was prepared similarly from 2b (0.082 g, 0.10
mmol) and Ph2P(CH2)4PPh2 (0.036 g, 0.084 mmol). The product
was isolated as an off-white solid. Yield: 0.083 g (80%). IR (KBr
disk): ν(CtC) 2133 cm-1. Anal. Calcd for C56H58Au2O2P2: C,
55.18; H, 4.80. Found: C, 55.51; H, 4.69. NMR for 6b in CD2Cl2:
δ(1H) 0.76 [s, 9H, CMe3]; 1.09-1.21 [m, 3H, Cy-H3-ax + Cy-H4-
ax]; 1.63-1.76 [m, 6H, PCH2CH2 + Cy-H3-eq]; 1.77-1.82 [m,
2
2H, Cy-H2-ax); 2.32 (br, 4H, PCH2); 2.71 (d, 2H, J(HH) ) 13
Hz, Cy-H2-eq]; 4.73 [s, 2H, OCH2-ax]; 4.78 [s, 2H, OCH2-eq]; 6.92
[d, 2H, 3J(HH) ) 8 Hz, C6H4-Ha-ax]; 7.01 [d, 2H, 3J(HH) ) 8 Hz,
3
C6H4-Ha-eq]; 7.16 [d, 2H, J(HH) ) 8 Hz, C6H4-Hb-ax]; 7.30 [d,
2H, 3J(HH) ) 8 Hz, C6H4-Hb-eq]; 7.41-7.50 [m, 12H, PPh]; 7.56-
7.61 [m, 8H, PPh]; δ(31P) 38.15 [s, P-ax]; 38.29 [s, P-eq]. Partial
NMR for 6b* in CDCl3 at 0 °C: δ(1H) 0.69 [s, 18H, CMe3]; 4.60
Acknowledgment. We thank the NSERC (Canada) for
financial support.
3
[s, 4H, OCH2-ax]; 4.75 [s, 4H, OCH2-eq]; 6.21 [d, 4H, J(HH) )
8 Hz, C6H4-Ha-ax]; 6.43 [d, 4H, 3J(HH) ) 8 Hz, C6H4-Ha-eq]; 6.66
[d, 4H, 3J(HH) ) 8 Hz, C6H4-Hb-ax]; 6.69 [d, 4H, 3J(HH) ) 8 Hz,
C6H4-Hb-eq]; δ(31P) 39.65 [s, P-ax]; 39.77 [s, P-eq]. Partial NMR
for 6b$ in CDCl3 at -40 °C: δ(1H) 0.72 [s, 18H, CMe3]; 4.67 [s,
Supporting Information Available: Complete X-ray data for
5a*‚3CH2Cl2 are available in CIF format free of charge via the
Internet at http://pubs.acs.org.
3
4H, OCH2-ax]; 4.80 [s, 4H, OCH2-eq]; 6.82 [d, 4H, J(HH) ) 8
3
Hz, C6H4-Ha-ax]; 6.92 [d, 4H, J(HH) ) 8 Hz, C6H4-Ha-eq]; 7.07
OM0601706