The crown ether phosphanes (PArPh2)-Ph-* (1) and PAr(*)2R [Ar-* = 3,4-(18-crown-6)-phenyl; R = Me (2); R = Ph (3)], prepared from PCl2R and (ArLi)-Li-*, have been studied. The syntheses and characterization of their oxides (4-6), and their BH3 (7-9), PdCl2 (10-12), and PtCl2 (13-15) complexes are reported. The molecular structure of the borane complex (PAr2PhBH3)-Ph-*-B-. (9) has been determined by X-ray structural analysis. Spectroscopic data suggest that phosphanes 1-3 have similar electronic properties and steric requirements to the corresponding phenylphosphane ligands PPh2Me and PPh3. Crown ether methylphosphane 2 and its complexes are remarkably water soluble, but 1 and 3 are only slightly soluble. Palladium(II) complexes 14 and 15 have been tested as catalysts in the Stille coupling of phenyltrichlorostannanes and aryl iodides in water. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).