In model reactions for the synthesis of phosphine-terminated tentacles
of polyamine dendrimers, the amides MeNHCOC(2)H(4)PPh(2) (2a) and (CH
(2)NHCOC(2)H(4)PPh(2))(2) (2b) were prepared from the spacer phosphine
(diphenylphosphino)propionic acid (1) and methylamine or ethylenediam
ine, respectively, using EDC [N-ethyl-N'-(3-(dimethylamino)propyl)carb
odiimide hydrochloride] as a coupling agent. By the same procedure, th
e dendritic, multifunctional species DAB-PPI-(NHCOC(2)H(4)PPh(2))(16)
(5a) and DAB-PPI-(NHCOC(2)H(4)PPh(2))(32) (5b) were obtained from diam
inobutane-poly(trimethyleneamine) dendrimers. The purification of prod
ucts 5a,b was followed by GPC methods, and the compounds were identifi
ed by analytical and NMR spectroscopic data. Treatment of the diphenyl
phosphino-terminated compounds 2a,b and 5a,b with equivalent amounts o
f (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 gro
ups (-PPh(2)AuCl) in good yields as stable colorless solids. Full cove
rage of all omega-phosphine functions was accomplished as confirmed ag
ain by NMR spectroscopy. For further delineation of the configuration
of the peptide-phosphine spacer tentacles, X-ray structure analyses we
re performed for MeNHCOC(2)H(4)PPh(2)AuCl (3a, triclinic, space group
P (1) over bar) and (CH2-NHCOC(2)H(4)PPh(2)AuCl)(2) (3b, monoclinic, s
pace group C2/c). The conformation of the molecules and their packing
can be rationalized on the basis of intermolecular NH...O hydrogen bon
ds, which in these cases exclude intra- and intermolecular Au-I...Au-I
contacts.