Dendrimer-Based Multinuclear Gold(I) Complexes

Article abstract of DOI:10.1021/ic950644l

In model reactions for the synthesis of phosphine-terminated tentacles of polyamine dendrimers, the amides MeNHCOC₂H₄PPh₂, (2a) and (CH₂NHCOC₂H₄PPh₂)₂ (2b) were prepared from the spacer phosphine (diphenylphosphino)propionic acid (1) and methylamine or ethylenediamine, respectively, using EDC [N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide hydrochloride] as a coupling agent. By the same procedure, the dendritic, multifunctional species DAB-PPI-(NHCOC₂H₄PPh₂)₁₆ (5a) and DAB-PPI-(NHCOC₂H₄PPh₂)₃₂ (5b) were obtained from diamrnobutane-poly(trimethyleneamine) dendrimers. The purification of products 5a,b was followed by GPC methods, and the compounds were identified by analytical and NMR spectroscopic data. Treatment of the diphenylphosphino-terminated compounds 2a,b and 5a,b with equivalent amounts of (dimethyl sulfide)gold-(I) chloride afforded the corresponding mono-, di-, hexadeca-, and dotriacontanuclear gold(I) complexes 3a,b and 6a,b, respectively, with terminal (diphenylphosphine)gold(I) chloride groups (-PPh₂AuCl) in good yields as stable colorless solids. Full coverage of all ω-phosphine functions was accomplished as confirmed again by NMR spectroscopy. For further delineation of the configuration of the peptide-phosphine spacer tentacles, X-ray structure analyses were performed for MeNHCOC₂H₄PPh₂AuCl (3a, triclinic, space group P1?) and (CH₂-NHCOC₂H₄PPh₂AuCl)₂ (3b, monoclinic, space group C2/c). The conformation of the molecules and their packing can be rationalized on the basis of intermolecular NH?O hydrogen bonds, which in these cases exclude intra- and intermolecular Au¹?Au¹ contacts.

Full text of DOI:10.1021/ic950644l

Inorg. Chem. 1996, 35, 637-642
637
Dendrimer-Based Multinuclear Gold(I) Complexes
Peter Lange, Annette Schier, and Hubert Schmidbaur*
Anorganisch-Chemisches Institut der Technischen Universita¨t Mu¨nchen, Lichtenbergstrasse 4,
D-85747 Garching, Germany
ReceiVed May 25, 1995X
In model reactions for the synthesis of phosphine-terminated tentacles of polyamine dendrimers, the amides
MeNHCOC2H4PPh2 (2a) and (CH2NHCOC2H4PPh2)2 (2b) were prepared from the spacer phosphine (diphen-
ylphosphino)propionic acid (1) and methylamine or ethylenediamine, respectively, using EDC [N-ethyl-N′-(3-
(dimethylamino)propyl)carbodiimide hydrochloride] as a coupling agent. By the same procedure, the dendritic,
multifunctional species DAB-PPI-(NHCOC2H4PPh2)16 (5a) and DAB-PPI-(NHCOC2H4PPh2)32 (5b) were
obtained from diaminobutane-poly(trimethyleneamine) dendrimers. The purification of products 5a,b was followed
by GPC methods, and the compounds were identified by analytical and NMR spectroscopic data. Treatment of
the diphenylphosphino-terminated compounds 2a,b and 5a,b with equivalent amounts of (dimethyl sulfide)gold-
(I) chloride afforded the corresponding mono-, di-, hexadeca-, and dotriacontanuclear gold(I) complexes 3a,b
and 6a,b, respectively, with terminal (diphenylphosphine)gold(I) chloride groups (-PPh2AuCl) in good yields as
stable colorless solids. Full coverage of all ω-phosphine functions was accomplished as confirmed again by
NMR spectroscopy. For further delineation of the configuration of the peptide-phosphine spacer tentacles, X-ray
structure analyses were performed for MeNHCOC2H4PPh2AuCl (3a, triclinic, space group P1h) and (CH2-
NHCOC2H4PPh2AuCl)2 (3b, monoclinic, space group C2/c). The conformation of the molecules and their packing
can be rationalized on the basis of intermolecular NH‚‚‚O hydrogen bonds, which in these cases exclude intra-
and intermolecular AuI‚‚‚AuI contacts.
Introduction
systems containing phosphorus functions in the framework of
the dendritic skeleton.5,8 R-(Diphenylphosphino)acetic and
Dendrimer-based metal complexes are expected to be a
particularly promising structural concept for new materials.1
Compared with conventional metal-containing organic poly-
mers,2 dendritic (Greek: branched) cascade molecules offer a
highly controlled architecture, which can be the basis for
dendrimer-supported metal complexes with new properties. With
the metal complexation limited to the terminal groups, all the
coordination centers should be readily accessible for stoichio-
metric or catalytic reactions. Except for sporadic studies
reported on polysiloxane-based nickel(II), polyamide-based
gadolinium(III), polyphosphine-based palladium(I), and poly-
imine-based gold(I) dendrimer complexes,3-6 the latter with
chain-end imido gold clusters of the type -N(AuIPPh3)3]+, very
little is known about surface coordination properties of den-
drimers.
p-(diphenylphosphino)benzoic acid have been employed as
tailored “spacers” to functionalize preformed dendritic polyamines
with terminal diphenylphosphino groups, which are ideal for
complexation of transition metals in low oxidation states.
As an extension of this study, we have now employed
â-(diphenylphosphino)propionic acid HOOCC2H4PPh2 (1) in the
synthesis of a new family of dendrimer-based multinuclear
gold(I) complexes. The third and fourth generations of dendritic
diaminobutane-poly(trimethyleneamine), DAB-PPI-(NH2)16
(4a) and DAB-PPI-(NH2)32 (4b), were coupled with â-(diphen-
ylphosphino)propionic acid (1) to give systems with phosphino-
amide tentacles of the type -NHCOC2H4PPh2.
Suitable coupling conditions for the systhesis of N-alkyl-
amides of 1 were probed and optimized using first methylamine
and ethylenediamine as the amine components and N-ethyl-N′-
(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) as
an efficient carbodiimide coupling agent. The resulting diphen-
ylphosphino-functionalized products 2a,b were employed as
ligands for gold(I) to give the corresponding phosphino-amide
complexes MeNHCOC2H4PPh2AuCl (3a) and (CH2NHCOC2H4-
PPh2AuCl)2 (3b), with (Me2S)AuCl as the source of the AuCl
components.
We recently introduced a new concept for surface-complexing
phosphorus-functional dendrimers,7 quite different from known
X Abstract published in AdVance ACS Abstracts, January 1, 1996.
(1) Tomalia, D. A.; Naylor, A. M.; Goddard, W. A. Angew. Chem. 1990,
102, 119; Angew. Chem., Int. Ed. Engl. 1990, 29, 138. Newkome, G.
R.; Moorefield, C. N. Aldrichim. Acta 1992, 25, 31. Engel, R. Polymer
News 1992, 17, 301. Mekelburger, H. B.; Jaworek, W.; Vo¨gtle, F.
Angew. Chem. 1992, 104, 1609; Angew. Chem., Int. Ed. Engl. 1992,
31, 1571. Tomalia, D. A. AdV. Mater. 1994, 6, 530.
(2) Sheats, J. E.; Carraher, C. E.; Pittman, C. U., Jr. Metal-Containing
Polymeric Systems; Plenum Press: New York, 1985. Pittman, C. U.,
Jr. In ComprehensiVe Organometallic Chemistry; Wilkinson, G., Stone,
F. G. A., Abel, E. W., Eds.; Pergamon Press: Oxford, U.K., 1982;
Chapter 55.
(3) Knapen, J. W. J.; van der Made, A. W.; de Wilde, J. C.; van Leeuwen,
P. W. N. M.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature 1994,
372, 659.
(4) Wiener, E. C.; Brechbiel, M. W.; Brothers, H.; Magin, R. L.; Gansow,
O. A.; Tomalia, D. A.; Lauterbur, P. C. Magn. Reson. Med. 1994, 31,
1.
This work was then extended to finally prepare DAB-PPI-
(NHCOC2H4PPh2AuCl)16 (6a) and DAB-PPI-(NHCOC2H4-
PPh2AuCl)32 (6b), with 16 and 32 terminal (diphenylphosphido)-
gold(I) chloride groups, respectively.
It was hoped that structural work on the model compounds
3a,b would give a clue as to the nature of inter- or intramolecular
(7) Lange, P.; Schier, A.; Schmidbaur, H. Inorg. Chim. Acta 1995, 235,
263.
(8) Launay, N.; Caminade, A.-M.; Lahana, R.; Majoral, J.-P. Angew.
Chem. 1994, 106, 1682; Angew. Chem., Int. Ed. Engl 1994, 33, 1589.
Sournies, F.; Graffeuil, M.; Crasnier, F.; Faucher, J.-P.; Lahana, R.;
Labarre, J.-F. Angew. Chem. 1995, 107, 610; Angew. Chem., Int. Ed.
Engl. 1995, 34, 578. Rengan, K.; Engel, R. J. Chem. Soc., Perkin
Trans. 1 1991, 987.
(5) Miedaner, A.; Curtis, J. C.; Barkley, R. M.; DuBois, D. L. Inorg. Chem.
1994, 33, 5482.
(6) Lange, P.; Beruda, H.; Hiller, W.; Schmidbaur, H. Z. Naturforsch.
1994, 49B, 781.
0020-1669/96/1335-0637$12.00/0 © 1996 American Chemical Society

638 Inorganic Chemistry, Vol. 35, No. 3, 1996
Lange et al.
°C. Anal. Calcd for 3a, C16H18AuClNOP (Mr ) 503.7): C, 37.54; H,
3.77; N, 3.08. Found: C, 38.15; H, 3.60; N, 2.78.
hydrogen bonds and/or Au‚‚‚Au contacts, resembling the
intertentacle interactions at the surface of the dendritic polyau-
rated products 6a,b. Solid-state structures of gold(I) compounds
often show short Au‚‚‚Au contacts near 3.0 Å which bear
witness to attractive forces associated with an energy on the
order of hydrogen bonding effects (20 kJ/mol) and unexpected
in the light of classical bonding concepts (AuI: [Xe]4f145d10).9
More recent calculations including relativistic effects have
demonstrated that these interactions can be rationalized as
correlation phenomena.10 The steric crowding in higher den-
drimer generations should favor metal-metal contacts.
31P{1H}-NMR (CDCl3), δ: 29.9 [s]. 1H-NMR (CDCl3), δ: 2.45
[m, 2H, CH2CP]; 2.66 [d, 3JHH ) 4.8, 3H, CH3]; 2.73 [m, 2H, CH2P];
6.03 [s, 1H, NH]; 7.35-7.63 [m, 10H, C6H5]. 13C{1H}-NMR (CDCl3),
1
2
δ: 23.8 [d, JCP ) 40.5, CH2P]; 26.4 [s, CH3]; 31.6 [d, JCP ) 5.5,
1
3
CH2CP]; 128.5 [d, JCP ) 60.7, Cipso]; 129.2 [d, JCP ) 12.0, Cmeta];
4
2
132.1 [d, JCP ) 2.8, Cpara]; 133.1 [d, JCP ) 13.8, Cortho]; 170.0 [d,
3JCP ) 16.5, CO]. FD-MS (CH2Cl2), m/z: 503.2 (100%, [M]+); 306.2
(5%, [M - Au]+); 271.2 (36%, [M - AuCl]+).
(CH2NHCOC2H4PPh2)2 (2b) and [2b(AuCl)2] (3b). Compounds
2b and 3b were prepared using the procedure described for 2a and 3a:
Ethylenediamine (0.58 g, 9.68 mmol) was treated with 2 equiv (19.36
mmol) each of â-(diphenylphosphino)propionic acid (1, 5.00 g), EDC
(3.71 g), and NEt3 (2.8 mL). Subsequent purification by crystallization
from diethyl ether/methanol gave colorless needles (2b; yield 4.00 g,
75%).
Experimental Section
All experiments were carried out in an atmosphere of purified
nitrogen, employing standard Schlenk techniques. The solvents were
dried, saturated with nitrogen, and distilled before use.
31P{1H}-NMR (CDCl3), δ: -15.6 [s]. 1H-NMR (CDCl3), δ: 2.23
[m, 4H, CH2CP]; 2.34 [m, 4H, CH2P]; 3.27 [s, 4H, C2H4]; 6.42 [s, 2H,
NH]; 7.28-7.39 [m, 20H, C6H5]. 13C{1H}-NMR (CDCl3), δ: 23.4
[d, 1JCP ) 12.0, CH2P]; 32.6 [d, 2JCP ) 18.4, CH2CP]; 39.9 [s, C2H4];
A JEOL GX 400 NMR spectrometer [solvent CDCl3, except for 3b
1
(DMF/C6D6, 10/1); TMS as internal standard for H and 13C, external
aqueous H3PO4 for 31P] and a Finnigan MAT 90 mass spectrometer
[FD source; solvent CH2Cl2] were employed. GPC analyses were
carried out with a Waters GPC station (pump 510, UV detector 486,
ultrastyragel 7.8 × 300 mm, polystyrene standards, M ) 50-10 000
g/mol) in THF as a solvent. Melting points (sealed capillaries in a
Bu¨chi apparatus) are uncorrected. The elemental analyses were
performed in the microanalytical laboratory of this Institute.
3
2
128.51 [d, JCP ) 6.4, Cmeta]; 128.54 [s, Cpara]; 132.6 [d, JCP ) 18.4,
1
3
C
ortho]; 137.7 [d, JCP ) 12.9, Cipso]; 172.3 [d, JCP ) 13.5, CO].
Product 2b (0.92 g, 1.70 mmol) was treated with Me2SAuCl (1.00
g, 3.40 mmol) to give a colorless microcrystalline solid: yield 1.62 g,
95%; mp 154 °C. Anal. Calcd for 3b, C32H34Au2Cl2N2O2P2 (Mr )
1005.4): C, 38.22; H, 3.40; N, 2.79. Found: C, 37.82; H, 3.51; N,
2.73.
â-(Diphenylphosphino)propionic acid (1)11 and (dimethyl sulfide)-
gold(I) chloride12 were prepared according to published methods.
Methylamine, ethylenediamine, and N-ethyl-N′-(3-(dimethylamino)-
propyl)carbodiimide hydrochloride (EDC) were purchased from Aldrich.
The diaminobutane-poly(trimethyleneamine) dendrimers DAB-PPI-
(NH2)16 and DAB-PPI-(NH2)32 were purchased from DSM Fine
Chemicals, P.O. Box 43, 6130 AA Sittard, The Netherlands.13
â-(Diphenylphosphino)propionic acid (1) was purified by repeated
recrystallization from aqueous 10% NaOH/2N HCl. Methylamine and
ethylenediamine were distilled before use.
31P{1H}-NMR (DMF + C6D6), δ: 30.0 [s]. 1H-NMR (DMF +
C6D6), δ: 5.60 [s, 2H, NH]; 7.36-7.65 [m, 20H, C6H5]. 13C{1H}-
NMR (DMF + C6D6), δ: 23.8 [d, 1JCP ) 40.0, CH2P]; 31.7 [d, 2JCP
)
1
5.5, CH2CP]; 40.0 [s, C2H4]; 129.2 [d, JCP ) 69.3, Cipso]; 129.6 [d,
3JCP ) 11.0, Cmeta]; 132.3 [s, Cpara]; 133.4 [d, 2JCP ) 12.9, Cortho]; 170.0
[d, 3JCP ) 15.8, CO]. FD-MS (CH2Cl2), m/z: 969.6 (53%, [M - Cl]+);
737.4 (100%, [M - AuCl2]+).
DAB-PPI-(NHCOC2H4PPh2)16 (5a) and [5a(AuCl)16] (6a). Com-
pounds 5a and 6a were prepared using the procedure described for 2a
and 3a: DAB-PPI-(NH2)16 (4a, 1.94 mmol, 3.27 g) was treated with
20 equiv (38.7 mmol) each of â-(diphenylphosphino)propionic acid
(10.00 g), EDC (7.42 g), and NEt3 (5.6 mL). Subsequent purification
by crystallization from ether/methanol (-30 °C) and benzene/hexane
(slow diffusion by layering at room temperature) gave a yellowish oil
(5a; yield 5.89 g, 55%).
MeNHCOC2H4PPh2 (2a) and [2a(AuCl)] (3a). A solution of
methylamine (0.10 g, 3.27 mmol) in 20 mL of CH2Cl2 was added to a
solution of 3.27 mmol of â-(diphenylphosphino)propionic acid (1, 0.85
g), EDC (0.63 g), and NEt3 (0.33 mL) in the same solvent (30 mL).
The reaction mixture was stirred for 3 h at ambient temperature, filtered
to remove N-ethyl-N′-(3-(dimethylamino)propyl)urea, washed with
saturated aqueous NaHCO3 and NaCl, and then dried over MgSO4.
After removal of the solvent, purification by crystallization from ether/
MeOH gave colorless needles (2a; yield 0.65 g, 73%).
GPC-UV (THF): t [min] ) 22.40 (100%), M [g/mol] ) 4479, Mz
[g/mol] ) 4406, Mw [g/mol] ) 4145, Mz/Mw ) 1.06. 31P{1H}-NMR
(CDCl3), δ: -15.37 [s]. 1H-NMR (CDCl3), δ: 1-4 [m, 240H, 120
CH2]; 7-8 [m, 160H, 32 C6H5]. Haliph/Harom: calcd, 1.50; found, 1.41.
13C{1H}-NMR (CDCl3), δ: 128.4 [d, 3JCP ) 6.4, Cmeta]; 128.6 [s, Cpara];
31P{1H}-NMR (CDCl3), δ: -15.2 [s]. 1H-NMR (CDCl3), δ: 2.24
[m, 2H, CH2CP]; 2.37 [m, 2H, CH2P]; 2.72 [d, 3JHH ) 4.6, 3H, CH3];
5.80 [s, 1H, NH]; 7.28-7.45 [m, 10H, C6H5]. (All J values are in
2
2
132.6 [d, JCP ) 18.4, Cortho]; 138.0 [d, JCP ) 12.0, Cipso]; 172.5 [d,
1
hertz.) 13C{1H}-NMR (CDCl3), δ: 23.4 [d, JCP ) 12.0, CH2P]; 26.2
3JCP ) 13.8, CO].
2
3
[s, CH3]; 32.5 [d, JCP ) 18.4, CH2CP]; 128.4 [d, JCP ) 7.4, Cmeta];
Product 5a (1.17 g, 0.21 mmol) was treated with stoichiometric
amounts of Me2SAuCl (16 equiv, 1.00 g, 3.40 mmol) to give a colorless
microcrystalline solid: yield 1.86 g, 95%; mp 95 °C. Anal. calcd for
6a, C328H416Au16Cl16N30O16P16 (Mr ) 9249.5): C, 42.59; H, 4.53; N,
4.54; P, 5.36; Au, 34.07. Found: C, 39.45; H, 4.37; N, 4.19; P, 4.44;
Au, 32.7.
2
1
128.7 [s, Cpara]; 132.6 [d, JCP ) 18.4, Cortho]; 137.8 [d, JCP ) 12.0,
ipso]; 170.2 [d, JCP ) 13.8, CO].
3
C
A solution of the product 2a (0.44 g, 1.69 mmol) in 20 mL of CH2-
Cl2 was added dropwise to a solution of (dimethyl sulfide)gold(I)
chloride (0.5 g, 1.69 mmol) in 20 mL of the same solvent, and the
reaction mixture was stirred for 2 h at room temperature. Removal of
the solvent and dimethyl sulfide in a vacuum left the crude product,
which was dissolved in 5 mL of CH2Cl2, and the solution was filtered
over cellulose to remove impurities of colloidal gold. Precipitation by
addition of hexane gave a pure product, which was dried in vacuo to
leave a colorless microcrystalline solid: yield 0.83 g, 95%; mp 213
31P{1H}-NMR (CDCl3), δ: 29.85 [s]. 1H-NMR (CDCl3), δ: 1-4
[m, 240H, 120 CH2]; 7-8 [m, 160H, 32 C6H5]. Haliph/Harom: calcd,
1
1.50; found, 1.47. 13C{1H}-NMR (CDCl3), δ: 128.6 [d, JCP ) 60.7,
3
2
C
ipso]; 129.2 [d, JCP ) 12.0, Cmeta]; 132.0 [s, Cpara]; 133.1 [d, JCP )
3
13.8, Cortho]; 170.2 [d, JCP ) 15.6, CO].
DAB-PPI-(NHCOC2H4PPh2)32 (5b) and [5b(AuCl)32] (6b).
Compounds 5b and 6b were prepared using the procedure described
for 2a and 3a: DAB-PPI-(NH2)16 (4b, 0.97 mmol, 3.40 g) was treated
with 40 equiv (38.7 mmol) each of â-(diphenylphosphino)propionic
acid (10.00 g), EDC (7.42 g), and NEt3 (5.6 mL). Subsequent
purification by crystallization from ether/methanol (-30 °C) and
benzene/hexane (slow diffusion by layering at room temperature) gave
a yellowish oil (5b; yield 5.75 g, 55%).
(9) Schmidbaur, H. Gold Bull. 1990, 23, 11. Schmidbaur, H. Interdiscip.
Sci. ReV. 1992, 17, 313.
(10) Pyykko¨, P.; Zhao, Y. Angew. Chem 1991, 103, 622; Angew. Chem.,
Int. Ed. Engl. 1991, 30, 604.
(11) Issleib, K.; Thomas, G. Chem. Ber. 1960, 93, 803.
(12) Dash, K. C.; Schmidbaur, H. Chem. Ber 1973, 106, 1221. Mann, F.
G.; Wells, A. F.; Purdie, D. J. Chem. Soc. 1937, 1828.
(13) de Brabander-van den Berg, E. M. M.; Meijer, E. W. Angew. Chem.
1993, 105, 1370; Angew. Chem., Int. Ed. Engl. 1993, 32, 1308. Jansen,
J. F. G. A.; de Brabander-van den Berg, E. M. M.; Meijer, E. W.
Science 1994, 266, 1226.
GPC-UV (THF): t [min] ) 22.08 (91%), M [g/mol] ) 5459, Mz
[g/mol] ) 5797, Mw [g/mol] ) 5459, Mz/Mw ) 1.06. 31P{1H}-NMR
(CDCl3), δ: -15.40 [s]. 1H-NMR (CDCl3), δ: 1-4 [m, 496H, 248

Dendrimer-Based Multinuclear Gold(I) Complexes
Inorganic Chemistry, Vol. 35, No. 3, 1996 639
Figure 1. Molecular structures of the two crystallographically inde-
pendent molecules A and B of compound 3a with atomic numbering
(CH3, CH2, and phenyl hydrogen atoms omitted for clarity). Selected
bond lengths [Å] and angles [deg]: Au1-P1 (Au2-P2) 2.230(2)
(2.225(2)), Au1-Cl1 (Au2-Cl2) 2.278(2) (2.276(3)), P1-C11 (P2-
C21) 1.810(9) (1.844(8)), C11-C12 (C21-C22) 1.529(12) (1.540(11)),
C12-C13 (C22-C23) 1.508(11) (1.509(12)), C13-O1 (C23-O2)
1.219(11) (1.224(10)), C13-N1 (C23-N2) 1.331(11) (1.318(12)), N1-
C14 (N2-C24) 1.454(11) (1.449(13)); Cl1-Au1-P1 (Cl2-Au2-P2)
176.09(8) (177.75(12)). For hydrogen bonds see Table 2.
CH2]; 7-8 [m, 320H, 64 C6H5]. Haliph/Harom: calcd, 1.55; found, 1.43.
13C{1H}-NMR (CDCl3), δ: 128.4 [d, 3JCP ) 6.4, Cmeta]; 128.5 [s, Cpara];
2
2
132.6 [d, JCP ) 18.4, Cortho]; 138.1 [d, JCP ) 12.0, Cipso]; 172.5 [d,
3JCP ) 13.8, CO].
Product 5b (1.19 g, 0.11 mmol) was treated with stoichiometric
amounts of Me2SAuCl (32 equiv, 1.00 g, 3.40 mmol) to give a colorless
microcrystalline solid: yield 1.88 g, 95%; mp 95 °C. Anal. Calcd
for 6b, C664H848Au32Cl32N62O32P32 (Mr ) 18 639.2): C, 42.78; H, 4.59;
N, 4.66; P, 5.32; Au, 33.82. Found: C, 38.55; H, 4.19; N, 4.38; P,
4.52; Au, 32.3.
Figure 2. Molecular structures of the two crystallographically inde-
pendent molecules A and B of compound 3b with atomic numbering
(CH3, CH2, and phenyl hydrogen atoms omitted for clarity). Selected
bond lengths [Å] and angles [deg]: Au1-P1 (Au2-P2) 2.229(2)
(2.228(2)), Au1-Cl1 (Au2-Cl2) 2.280(2) (2.284(2)), P1-C11 (P2-
C21) 1.822(6) (1.820(7)), C11-C12 (C21-C22) 1.501(9) (1.535(10)),
C12-C13 (C22-C23) 1.518(9) (1.505(9)), C13-O1 (C23-O2) 1.238-
(8) (1.235(8)), C13-N1 (C23-N2) 1.331(8) (1.339(9)), N1-C14 (N2-
C24) 1.435(8) (1.448(8)), C14-C14a (C24-C24a) 1.533(14) (1.539(13));
Cl1-Au1-P1 (Cl2-Au2-P2) 178.90(7) (176.03(7)). For hydrogen
bonds see Table 2.
31P{1H}-NMR (CDCl3), δ: 29.75 [s]. 1H-NMR (CDCl3), δ: 1-4
[m, 496H, 248 CH2]; 7-8 [m, 320H, 64 C6H5]. Haliph/Harom: calcd,
1
1.55; found, 1.46. 13C{1H}-NMR (CDCl3), δ: 128.6 [d, JCP ) 60.5,
3
2
C
ipso]; 129.1 [d, JCP ) 12.0, Cmeta]; 131.9 [s, Cpara]; 132.9 [d, JCP )
3
13.8, Cortho]; 170.1 [d, JCP ) 16.5, CO].
Structural Data. Suitable crystals of 3a and 3b were mounted in
glass capillaries and used for measurements of precise cell constants
and intensity data collection. During data collection, three standard
reflections were measured periodically as a general check of crystal
and instrument stability. No significant changes were observed for
both compounds. Diffraction intensities were corrected for Lp and
absorption effects. The thermal motion of all non-hydrogen atoms was
treated anisotropically. All phenyl, methyl, and methylene hydrogen
atoms were placed in idealized calculated positions and allowed to ride
on their corresponding carbon atom. The N-H atoms were located
and included with fixed isotropic contributions (Uiso(fix) ) 0.08 Å2).
Crystals of compounds 3a and 3b contain two crystallographically
independent molecules, which show only marginal differences in
dimensions but different conformations, as shown in Figures 1 and 2.
Further information on crystal data, data collection, and structure
solution and refinement is summarized in Table 1. Hydrogen bonds
in the crystals of 3a and 3b are listed in Table 2. Important interatomic
distances and angles are summarized in the corresponding figure
captions.
After completion of the reactions in CH2Cl2, aqueous workup
to remove the EDC byproduct (a urea derivate), and crystal-
lization from ether/MeOH, the products are obtained in about
70% yield as colorless needles (2a,b) and yellowish oils (5a,b),
soluble in most common organic solvents. In the case of the
polychelate ligands 5a,b, remaining traces of the coupling agents
and incompletely functionalized defect species have to be
removed by a further purification step (benzene/hexane).
Treatment of the phosphino amides 2a,b and 5a,b with Me2-
SAuCl gives the mono-, di-, hexadeca-, and dotriacontanuclear
gold(I) complexes 3a,b and 6a,b, respectively, in 95% yield,
with liberation of dimethyl sulfide. In each case, all the terminal
diphenylphosphino groups have been found to be engaged as
coordination sites for the gold(I) chloride units. None of the
amido or imino functions are employed in coordination to gold-
(I). The complexes are obtained as colorless solids (from CH2-
Cl2/hexane), stable to air and moisture but light-sensitive,
especially in solution.
Results and Discussion
The reactions of methylamine and ethylenediamine with
â-(diphenylphosphino)propionic acid (1), in the presence of
N-ethyl-N′-(3-(dimethylamino)propyl)carbodiimide hydrochlo-
ride (EDC) and triethylamine as coupling agents, result in
quantitative formation of the corresponding diphenylphosphino
amides 2a,b (Scheme 1).
The branched polyamines DAB-PPI-(NH2)16 (4a) and
DAB-PPI-(NH2)32 (4b), with 16 and 32 terminal primary
amino groups, respectively, afford the corresponding multi-
functional species 5a,b, when treated with the same reagents
(Schemes 2 and 3).
The analytical and spectroscopic data of 2a,b, 3a,b, 5a,b,
and 6a,b are in good agreement with the proposed stoichiom-
etries and structures (Experimental Section). Compounds 3a,b
have also been characterized by X-ray diffraction.
The GPC chromatograms of the purified polyfunctional
ligands 5a,b show only one major peak, indicating the successful
removal of almost all the residues of the coupling agents.
Discrepancies between calculated and found elemental analysis
data are due to traces of impurities and inclusions of solvent.
Since linear standards were used for GPC analyses, the GPC
peaks of the spheric molecules 5a (M ) 5531 g/mol) and 5b

640 Inorganic Chemistry, Vol. 35, No. 3, 1996
Lange et al.
Table 1. Crystal Data and Details of the Data Collection and
Structure Solution and Refinement for Compounds 3a and 3b
Scheme 1
3a
3b
Crystal Data
C16H18NOPAuCl
503.72
formula
Mr
crystal system
space group
a (Å)
b (Å)
c (Å)
C32H34N2O2P2Au2Cl2
1005.43
monoclinic
C2/c [No. 15]
21.242(2)
18.428(3)
18.422(3)
90
96.82(1)
90
7160.2
1.865
8
triclinic
P1h [No. 2]
9.114(1)
12.733(2)
18.501(3)
99.98(1)
99.47(1)
109.72(1)
1932.1
R (deg)
â (deg)
γ (deg)
V (Å3)
F
calc (g cm-3
Z
)
1.731
4
Scheme 2
F(000) (e)
960
78.09
3824
84.29
µ(Mo KR) (cm-1
)
Data Collection
diffractometer
radiation
λ(Mo KR) (Å)
T (°C)
Enraf-Nonius CAD4
Mo KR
Mo KR
0.710 69 (graphite monochromator)
-59
θ-θ
+11,(16,(23
0.64
8391
8332
5968
-59
θ-θ
+28,(24,(24
0.66
8571
8571
6275
scan mode
hkl range
((sin θ)/λ)max (Å-1
)
no. of measd reflns
no. of unique reflns
no. of obsd reflns
Fo g
4σ(Fo)
DIFABS
4σ(Fo)
DIFABS
abs cor
Refinement
379
Patterson methods Patterson methods
no. of refined params
structure soln
379
H atoms (found/calcd) 2/34
2/32
0.0382
0.0881
R1a
0.0418
wR2b
0.0983
(shift/error)max
<0.001
<0.001
Ffin(max/min (e Å-3
)
+2.06/-1.31c
+3.84/-0.89c
a R1 ) ∑(||Fo| - |Fc||)/∑|Fo|. b wR2 ) [∑w(Fo - Fc )2]/
2
2
2
2
2
∑[w(Fo )2]1/2; w ) q/σ2(Fo ) + (ap)2 + bp; p ) max(Fo ,0) + 2Fc2/3;
a ) 0.0502 (3a), 0.0464 (3b); b ) 11.64 (3a), 54.89 (3b). c Residual
electron densities located at Au atoms.
Table 2. Hydrogen Bonds in the Structures of 3a and 3ba
D-H‚‚‚A,
distinct sets, but signal superpositions of similar CH2 groups
make assignment of most aliphatic resonances tentative.
Assuming similar T1 values for aliphatic and aromatic protons,
compd
D-H‚‚‚A
D-H, Å H‚‚‚A, Å D‚‚‚A, Å
deg
1
the observed ratio of intensities Haliph/Harom in the H-NMR
3a
N1-H1‚‚‚O2i
0.860
0.860
1.970
1.933
2.019
1.960
2.816
2.791
2.823
2.813
167.6
174.8
155.1
171.6
N2-H2‚‚‚O1ii
spectra of 5a,b and 6a,b corroborate the successful polyfunc-
tionalization of the dendrimers. Note that all phenyl groups
present in the products have been introduced by â-(diphen-
ylphosphino)propionic acid (1) as a spacer and are thus a direct
measure of the functionalization.
3b
N1-H1‚‚‚O2iii 0.860
N2-H2‚‚‚O1i
0.860
a Symmetry positions of atoms A: (i) x - 1, y + 1, -z; (ii) x, y -
1, z; (iii) x, y, z + 1; (iv) x, -y, z - 0.5.
Solvent-free single crystals of MeNHCOC2H4PPh2AuCl (3a,
triclinic, space group P1h) and (CH2NHCOC2H4PPh2AuCl)2 (3b,
monoclinic, space group C2/c) were obtained from benzene/
diethyl ether and DMF/diethyl ether, respectively. An inspection
of the data in the captions to Figures 1 and 2 shows that most
of the structural parameters of 3a,b agree generally quite well
with those observed for comparable gold(I) complexes of
phosphino amides.7
(M ) 11202 g/mol) appear at lower molar masses, M5a ) 4479
g/mol and M5b ) 5459 g/mol, due to the long retention times.
Proton-, 13C{1H}-, and 31P{1H}-NMR data confirm the
virtually complete functionalization of all primary amines (to
give 5a,b) and auration (to give 6a,b). In the 31P{1H}-NMR
spectra of 5a,b and 6a,b, the 16 and 32 equivalent diphen-
ylphosphino groups, respectively, give rise to singlets, indicating
the absence of any defect species, except for the traces of
phosphine oxides detected at +34 ppm. Upon AuCl complex-
ation these low-intensity signals remain unchanged, both in
chemical shift and in relative intensity, whereas the main signals
show a significant downfield shift from δ5a ) -15.4 ppm to
δ6a ) +29.9 ppm (∆δ ≈ +45 ppm) and from δ5b ) -15.4
ppm to δ6b ) +29.8 ppm (∆δ ≈ +45 ppm), respectively.
In the 13C{1H}-NMR spectra of 5a,b and 6a,b, the ipso, ortho,
meta, and para phenyl-C signals can be readily identified as
There are two independent molecules with different confor-
mations (A, B) in the asymmetric unit of compound 3a, and
likewise in the asymmetric unit of compound 3b. The molecular
structures of both species A and B of 3a (which have no
crystallographic symmetry) are shown in Figure 1. Both
molecules are mainly distinguished by their O1-C13-C12-
C11 (+38.4°) and O2-C23-C22-C21 (-49.2°) dihedral
angles. Intermolecular NH‚‚‚O hydrogen bonds direct the

Dendrimer-Based Multinuclear Gold(I) Complexes
Inorganic Chemistry, Vol. 35, No. 3, 1996 641
Scheme 3
Figure 4. Crystal packing in the unit cell of 3b showing the
intermolecular hydrogen bonds (see also Table 2).
up to two NH‚‚‚O hydrogen bonds. Thus aggregation via gold-
gold interactions is not to be expected, although both types of
secondary bonding are of comparable energy (20 kJ/mol).9
In multinuclear complexes 6a,b a combination of intertentacle
N-H‚‚‚O and AuI‚‚‚AuI bonding is more likely; especially for
complex 6b, with its compact surface of 32 terminal (diphen-
ylphosphido)gold(I) groups, the peripheral network must include
Au‚‚‚Au contacts, complementary to the peptide hydrogen-
bonding framework. Luminescence and EXAFS studies are
under way to clarify this point.
Conclusions
In the present study we have established a new concept for
the preparation of dendritic amines/amides with terminal phos-
phino donor functions for surface complexation. The third and
fourth generations of dendritic diaminobutane-poly(trimethyl-
eneamines), DAB-PPI-(NH2)16 and DAB-PPI-(NH2)32, and
the model amines methylamine and ethylenediamine were
employed for the functionalization with peripheral diphe-
nylphosphino groups. Their chain-end primary amino groups
can be coupled with â-(diphenylphosphino)propionic acid as a
spacer suitable for auration to give the corresponding mono-,
di-, hexadeca-, and dotriacontanuclear species with terminal
(diphenylphosphido)gold(I) chloride groups (-NHCOC2H4PPh2-
AuCl). These multinuclear gold(I) complexes represent a new
type of metal-containing polymer of a well-defined, probably
spherical structure with branched dendrimer molecules as
supporting matrices. Apart from potential applications of the
new polychelate ligands 5a,b in catalysis, the polynuclear gold-
(I) complexes 6a,b are expected to be valuable in biochemical
diagnostics and imaging and in medicine as antiinflamatory and
antitumor drugs. Gold(I) compounds have been employed very
Figure 3. Crystal packing in the unit cell of 3a showing the
intermolecular hydrogen bonds (see also Table 2).
aggregation of the molecules in the solid state to give chainlike
structures (Figure 3, Table 2).
Both species A and B of the formula 3b as well as of 3a
adopt conformations which allow utilization of all NH and CdO
groups for intermolecular hydrogen bonds (Figures 2 and 4,
Table 2). The conformers of 3b differ significantly in sym-
metry. While molecule A exhibits an inversion center (point
group Ci), a rotation axis describes the symmetry of molecule
B (point group C2).
It appears that the hydrogen-bonding networks of 3a,b are
holding the PAuCl groups apart, thus overruling possible gold-
gold contacts, which are common in solid-state structures of
-C2H4PPh2AuICl compounds.14 This result is perhaps not
unexpected since the molecules 3a,b with one PAuCl unit per
NHCO amide group can support only one Au‚‚‚Au contact but
(14) Schmidbaur, H.; Graf, W.; Mu¨ller, G. Angew. Chem. 1988, 100, 439;
Angew. Chem., Int. Ed. Engl. 1988, 27, 417. Dziwok, K.; Lachmann,
J.; Wilkinson, D. L.; Mu¨ller, G.; Schmidbaur, H. Chem. Ber. 1990,
123, 423. Schmidbaur, H.; Bissinger, P.; Lachmann, J.; Steigelmann,
O. Z. Naturforsch. 1992, 47B, 1711. Stu¨tzer, A.; Bissinger, P.;
Schmidbaur, H. Chem. Ber. 1992, 125, 367; Z. Naturforsch. 1992,
47B, 640.

642 Inorganic Chemistry, Vol. 35, No. 3, 1996
Lange et al.
succesfully for treatment of rheumatoid diseases.15 According
to established formulations, the chloride atoms in compounds
6a,b should be substituted by thiolate ligands for optimized
performance.
strie, andsthrough the donation of chemicalssby Degussa AG,
Heraeus GmbH, and DSM Fine Chemicals. We thank Dr. B.
Voit for GPC spectra, Professor F. R. Kreissl for mass spectra,
and J. Riede for establishing the X-ray data sets.
Acknowledgment. This work was supported by the Deutsche
Supporting Information Available: Listings of crystallographic
data and data collection and refinement details, atomic positional
parameters, anisotropic thermal parameters, bond distances, and bond
angles (14 pages). Ordering information is given on any current
masthead page.
Forschungsgemeinschaft, by the Fonds der Chemischen Indu-
(15) Reardon, J. E.; Frey, P. A. Biochemistry 1984, 23, 3849. Jahn, W. Z.
Naturforsch. 1989, 44B, 1313. Mirabelli, C. K. J. Med. Chem. 1987,
30, 2181. Sadler, P. J. In Frontiers in Bioinorganic Chemistry; Xavier,
A. V., Ed.; VCH: Weinheim, Germany, 1986; p 376. Dash, K. C.;
Schmidbaur, H. In Metal Ions in Biological Systems; Sigel, H., Ed.;
Marcel Dekker: New York, Basel, 1982; Vol. 14, p 179.
IC950644L