Catalano et al.
Scheme 1
phino)pyridazine) would coordinate to gold(I) in a polymeric
fashion or whether it would form a metallocryptand. Interest-
ingly, it does both, and here we report the formation of two
polymeric complexes of Au(I), their interconversion, and
their conversion to an empty metallocryptand.
Results
According to Scheme 2, the two-dimensional polymer
{Au2Cl2(P2pz)3}n, 1‚6CHCl3, was prepared by reacting 1
equiv of AuCl(tht) (tht is tetrahydrothiophene) with 1.5 equiv
of P2pz in chloroform giving a pale yellow solution. Also
seen in Scheme 2 is the one-dimensional polymeric complex
{[Au2(P2pz)3](PF6)2}n, 2, prepared by reacting 1 with excess
NH4PF6 in a 1:1 dichloromethane/methanol mixture. The
simple digold complex (AuCl)2(P2pz), 3, is formed by the
reaction of 2 equiv of AuCl(tht) with 1 equiv of P2pz giving
rise to a sharp singlet in the 31P{1H} NMR spectrum at 33.0
ppm. Additionally, 1 can be formed by the reaction of 3 with
2 equiv of P2pz in chloroform or by the reaction of 2 with
Et4NCl in chloroform. All reactions to form 1 produce
31P{1H} NMR spectra that show a broad resonance at 23.6
ppm, indicative of a dynamic process, and two smaller
resonances at 20.2 and 19.8 ppm, identified as the diphos-
phine oxide and monophosphine oxide comprising only 5%
of the total spectrum. Moreover, the macrocyclic polymer,
2, may be formed by reacting 3 with NH4PF6 and 2 equiv
of P2pz in a dichloromethane/methanol mixture or directly
by reacting 1 equiv of AuCl(tht) with 1.5 equiv of P2pz with
excess NH4PF6 in the same solvent. Similar to the for-
mation of 1, reactions to form 2 also give rise to a broad
31P{1H} NMR resonance indicative of a dynamic process
(41.1 ppm for the phosphorus atoms of the P2pz ligand
and a heptet at -142.7 ppm for the phosphorus atom of the
P2nap where P2phen is 2,9-bis(diphenylphosphino)-1,10-
phenanthroline and P2bpy is 6,6′-bis(diphenylphosphino)-
2,2′-bipyridine.4 During these studies, we have never ob-
served polymer formation even though there are numerous
examples of coordination polymers using late transition
metals and multidentate ligands.5
The importance of metal containing polymers for new
materials is quite extensive,6 and Au(I) based polymers are
of particular importance due to their unique photophysical
properties.7,8 Often complexes with inter- or intramolecular
Au(I)‚‚‚Au(I) interactions are intensely luminescent, and
perturbations of these interactions can form the basis of a
luminescent sensor.9 The ability to form polymeric complexes
is often dictated by the geometry of the multidentate ligand.
A large number of ligands, particularly multidentate phos-
phine ligands, have been designed to hold gold atoms in close
proximity to each other. Because gold(I) complexes are
known to adopt a variety of coordination modes, including
two-, three-, or four-coordinate, it was of interest to see if
the tetradentate P2pz ligand (P2pz is 3,6-bis(diphenylphos-
(5) (a) Moulton, B.; Zaworotko, M. J. Chem. ReV. 2001, 101, 1629-
1658. (b) Swiegers, G. F.; Malefetse, T. J. Chem. ReV. 2000, 100,
3483-3587.
(6) (a) Manners, I. J. Chem. Soc., Chem. Commun. 1999, 857-858. (b)
Blake, A. J.; Champress, N. R.; Hubberstey, P.; Li, W. S.; Withersby,
M. A.; Schroeder, M. Coord. Chem. ReV. 1999, 183, 117-138. (c)
Inorganic and Organometallic Polymers II: AdVanced Materials and
Intermediates; Wisian-Neilson, P., Allcock, H. R., Wynne, K. J., Eds.;
ACS Symposium Series 572; American Chemical Society: Washing-
ton, DC, 1994. (d) Inorganic and Organometallic Polymers; Zeldin,
M., Wynne, K. J., Allcock, H. R., Eds.; ACS Symposium Series 360;
American Chemical Society: Washington, DC, 1988. (e) Metal
Containing Polymeric Systems; Sheats, J. E., Carraher, C. E., Jr.,
Pittman, C. U., Jr., Eds.; Plenum: New York, 1985.
-
PF6 anion (1JF-P ) 704 Hz)). Further, the empty metallo-
cryptand complex Au2I2(P2pz)3, 4, can also be produced by
a variety of methods as shown in Scheme 2. Complex 4
forms by reacting 2 with excess NaI in a 2:1 dichlo-
romethane/methanol mixture, reacting 1 with excess NaI also
in a dichloromethane/methanol mixture, or by reacting 3
equiv of P2pz with 2 equiv of AuCl(tht) and excess NaI. All
of these reactions give rise to a variety of resonances in the
31P{1H} NMR spectrum with the largest resonance (compris-
ing 95% of the spectrum) at 15.3 ppm. Once crystallized,
compound 4 is insoluble in common organic solvents
including dimethyl sulfoxide, acetone, acetonitrile, dichlo-
romethane, chloroform, and methanol, and 31P{1H} NMR
spectra could not be obtained on the isolated product.
As indicated by the broad 31P{1H} NMR resonances, the
polymeric complexes 1 and 2 are dynamic in solution and
freely exchange ligand. This exchange process was explored
by 31P{1H} NMR spectroscopy by successive additions of
(7) Puddephatt, R. J. Coord. Chem. ReV. 2001, 216-217, 313-332.
(8) (a) Brandys, M.-C.; Puddephatt, R. J. J. Am. Chem. Soc. 2001, 123,
4839-4840. (b) Leznoff, D. B.; Xue, B.-Y.; Batchelor, R. J.; Einstein,
F. W. B.; Patrick, B. O. Inorg. Chem. 2001, 40, 6026-6034. (c)
Brandys, M.-C.; Puddephatt, R. J. J. Chem. Soc., Chem. Commun.
2001, 1280-1281. (d) Brandys, M.-C.; Jennings, M. C.; Puddephatt,
R. J. J. Chem. Soc., Dalton Trans. 2000, 4601-4606. (e) Ferna´ndez,
E. J.; Gimeno, M. C.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Menge,
M.; Pyykko¨, P.; Sundholm, D. J. Am. Chem. Soc. 2000, 122, 7287-
7293. (f) Hunks, W. J.; Jennings, M. C.; Puddephatt, R. J. Inorg. Chem.
1999, 38, 5930-5931. (g) Puddephatt, R. J. J. Chem. Soc., Chem.
Commun. 1998, 1055-1062. (h) Irwin, M. J.; Vittal, J. J.; Puddephatt,
R. J. Organometallics 1997, 16, 3541-3547. (i) Van Calcar, P. M.;
Olmstead, M. M.; Balch, A. L. Inorg. Chem. 1997, 36, 5231-5238.
(j) Irwin, M. J.; Jia, G.; Payne, N. C.; Puddephatt, R. J. Organome-
tallics 1996, 15, 51-57. (k) Irwin, M. J.; Vittal, J. J.; Yap, G. P. A.;
Puddephatt, R. J. J. Am. Chem. Soc. 1996, 118, 13101-13102. (l)
Tzeng, B.-C.; Cheung, K.-K.; Che, C.-M. J. Chem. Soc., Chem.
Commun. 1996, 1681-1682. (m) Van Calcar, P. M.; Olmstead, M.
M.; Balch, A. L. J. Chem. Soc., Chem. Commun. 1995, 1773-1774.
(n) Jia, G.; Payne, N. C.; Vittal, J. J.; Puddephatt, R. J. Organometallics
1993, 12, 4771-4778. (o) Jia, G.; Puddephatt, R. J.; Scott, J. D.; Vittal,
J. J. Organometallics 1993, 12, 3565-3574.
1
P2pz to AuCl(tht). Addition of /2 equiv of P2pz to 1 equiv
of AuCl(tht) produces a single sharp resonance at 33.0 ppm
that is attributed to the formation of Au2Cl2(P2pz), 3. Addition
1
of a second /2 equiv of P2pz causes the sharp resonance at
33.0 ppm to broaden slightly and diminish in intensity while
two other broad resonances are seen at 24.0 and 23.6 ppm.
(9) Mansour, M. A.; Connick, W. B.; Lachicotte, R. J.; Gysling, H. J.;
Eisenberg, R. J. Am. Chem. Soc. 1998, 120, 1329-1330.
1
Addition of yet another
/ equiv of P2pz significantly
2
2142 Inorganic Chemistry, Vol. 42, No. 6, 2003