Kailash C. Dash

N- or P-coordination in Di- and triazaphosphole gold complexes

Abstract AuCl and (CH 3 ) 2 AuCl complexes of the following series of azaphospholes have been prepared and characterized by analytical and spectroscopic data: 2,5-dimethyl-1,2,3-diazaphosphole (1), 5-methyl-2-phenyl-1,2,3-diazaphosphole (2), 2-methyl-5-phenyl-1,2,4,3-triazaphosphole (3), and 1,5-dimethyl-1,2,4,3-triazaphosphole (4). The (CH 3 ) 2 AuCl complexes are assigned a planar cis -structure with P-coordination for 2 and 3, but N-coordination for 1 and 4. Imidazole forms a 1:1 complex with (CH 3 ) 2 AuCl (9), but a 2:1 complex with AuCl (10). Low solubilities of the 1:1 complexes of AuCl with the azaphospholes preclude detailed structure analyses in solution. The complexes are of interest for pharmacological studies.

Compounds of Gold in Unusual Oxidation States

Publisher Summary This chapter discusses the compounds of gold in unusual oxidation states. Some of the most exciting developments in gold chemistry were initiated by the discovery of unusual oxidation states. As a general rule, the chemistry of metal ions in solution is characterized by the ability to form positive ions. The stable negative metal ions are well characterized only in the gas phase. Mercury forms a monoatomic vapor and behaves like an inert gas in this respect. Most of the cluster molecules or ions are stable to air and water and are easily characterized by modern physical techniques, although yields of most preparations are low. Application of other synthetic techniques, predominantly metal vapor methods, have added other cluster stoichiometries to this list, which presently includes Au 5 , Au 6 , Au 8 , Au 9 , and Au ll .

Gold Complexes of a P-Coordinate Cyclotriphosphazene [1,2]

Abstract Contrary to the reports on the coordination oi copper (I) to N/P-ambidentate cyclotri-phosphazenes, gold (I), gold (III) and dimethylgoldf 111) chloride are found to become exclusively P-coordinated to the prototype ligand 2-methyl-4,4,6,6-tetraphenylcyclotri-phosphazene (1). The P-H proton is transferred to an adjacent nitrogen atom of the heterocycle. According to temperature dependent NMR spectra, the AuCl and the AuCl3 complexes are fluxional molecules or ions, resp., with a rapid proton transfer between P-NH-P and P = N-P functions. The behaviour is similar to that of related palladium and platinum complexes, reported previously.

Gold(I)-Bis(diphenylphosphino)amid und einige Gold(I)-Bis(diarylphosphino)methanide mit sterisch anspruchsvollen Arylsubstituenten / Gold(I)-bis(diphenylphosphino)amide and Some Gold(I)-bis(diarylphosphino)methanides with Bulkyl Aryl Substituents

Intensely yellow coloured, insoluble gold(I)-bis(diarylphosphino)amides, [(C6H5)P2NAu, 1, is obtained from lithiated bis(diphenylphosphino)amine and AuCl complexes of tertiary phosphines. 1 is assigned a dimeric eightmembered ring structure on the basis of its 197Au-Mößbauer spectrum and of a direct analogy with the corresponding bis(phosphino)methanide complexes, whose structure has recently been confirmed by X-ray diffraction. A series of mono- and binuclear AuCl complexes of bis(diarylphosphino)methanes bearing bulky 2-tolyl or 2,6-dimethylphenyl substituents (3a, b) was synthesized from the diphosphines and (CO)AuCl in the molar ratios 1:2 or 1:1. The compounds have structures 4 a, b and oa, b, respectively. An ionic tetrafluoroborate derivative 6 b was obtained from the chloride 5 b on treatment with AgBF4. Lithiation of the diphosphinomethanes 3 a, b using LiCH3 followed by reaction with CIAuPR3 complexes yields the deep-yellow Au(I) bis(diarylphosphino)methanides 7 a, b. All compounds, including the new ligand 3b and its precursor (2,6-(CH3)2C6H3)2PBr, 2, were characterized by analytical and spectroscopic data.