Abstract

A cyclotriphosphazene bearing two 4-oxypyridine groups on the same phosphorus atom, gem-[N3P3(O2C 12H8)2(OC5H4N-4) 2] (I), and its analogous polymer [[NP-(O2C 12H4)UNP(OC5H4NM)2) 0.3]n (II), have been used to prepare gold or silver, cyclic and polymeric, metallo-phosphazenes. The following complexes, gem-[N 3P3(O2C12H8) 2(OC5H4N4(ML})2] (ML = Au(C 6F5) (1) or Au(C6F5)3 (2)), [N3P3(O2C12H8) 2(OC5H4N4[AuPPh3)),] [NO 3], (3), and [N3P3-(O2C 12H8)2(OC3H4N- 4{AgPPh2R))2][SO3CF3]2 (R = Ph (4) or Me (5)) have been obtained. Complexes 1 and 4 are excellent models for the preparation of the analogous polymers [(NP(O2C 12H8)}0.7{NP(OC5H 4N-4{ML})2}0.3]n (ML = Au(C 6F5) (Pl), Ag(OSO2CF3)PPh 3 (P2)). All complexes have been characterized by elemental analysis, various spectroscopic methods, and mass spectrometry. The polymers were further investigated by thermochemical methods (thermogravimetric analysis) and differential scanning calorimetry. For compounds 1-5 and for the starting phosphazene I, a mixture of different stereoisomers may be expected. The stereochemistry in solution has been studied by variable-temperature NMR spectroscopy studies, which provided evidence for interconversion processes that involve changes in the chirality of a 2,2'-dioxybiphenyl group. A singlecrystal X-ray analysis of the gold complex 2 confirmed not only the proposed structure, but also S,S and R,R configurations at the two biphenoxy-substituted phosphorus centers, in contrast to those observed for the precursor I. Pyrolysis of these new metallophosphazenes was also studied. Notably, pyrolysis of the gold derivatives gave macroporous metallic gold sponges without the requirement of either an external reducing agent or a porous support. These materials were all characterized by XRD, TEM, SEM, and energy-dispersive X-ray spectroscopy. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.