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A series of (isonitrile)gold(I) complexes has been synthesized: (MeNC)AuX (X = Cl la, I lc), (t-BuNC)AuBr 2b. (PhNC)AuX (X = Cl 3a. Br 3b. I 3c. SCN 3d), (MesNC)AuCl 4a [mes=mesityl], and (MeOC(O)CH2NC)AuX (X = Cl 5a. Br 5b. I 5c. SCN 5d). The chlorides were prepared by the reaction of (Me2S)AuCl with equimolar amounts (or with an excess) of the corresponding isonitrile. The bromides, iodides and thiocyanates were obtained from the reaction of (RNC)AuCl with K+X- (X = Br, I, SCN) in the two-phase system H2O/CH2CI2. The molecular and crystal structures of la. 2b. 3a-c, 4a, and 5a-c have been determined by X-ray diffraction methods. In the solid state the molecules are aggregated through short Au-Au contacts into dimers (4a and 5c), chains (la, 2b and 3a-c) or sheets (5a and 5b). The influence of the isonitrile and halide ligands on the type and strength of the intermolecular Au-A u contacts is discussed

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Key Words: 1,3,5-Triaza-7-phospha-adamantane / Reductive cleavage of phosphonium salts t Ambidentate P,N-ligands t P,N-[3.3.l]bicyclononane systems t Phosphanes Two reaction pathways for the synthesis of 1,3,5-triaza-?-phosphoniaadamantane salts, RP[(CH2)6N3]+X-(l), were followed. Route 1 starts with commercial tetrakis(hydroxymethy1)phosphonium chloride, which is converted into P(CH,OH), by treatment with a base. Subsequent quaternization with alkyl halides RX and cyclization with formaldehyde and ammonia afford [R-TPA]+X-. This process is only applicable for R = Me (la) and Et (lb), however. Route 2 is more general and starts with primary phosphanes RPH,, which are converted into organotris(hydroxymethy1)phosphonium salts with formaldehyde and hydrochloric acid followed by ring closure with CH20/NH3 to give compounds l c -l f (R = t-Bu, c-Hex, Bz, and Ph, respectively, and X = C1, I, PFs, or BPh4). Reductive cleavage of compounds 1 by sodium in liquid ammonia proceeds with either external (P-R) or internal (P-CH2) bond rupture. P-R cleavage affords the 1,3,5-triaza-?-phosphaadamantane (TPA), while cage cleavage leads to new bowl-or helmet-shaped ligand systems with peripheral amine and phosphane functions (2). Yields of the cage-opening reaction are highest for R = Ph (2f), moderate for R = Me and Et (2a, 2b), and poor with the remaining R groups (2c-2e). A radical mechanism is proposed for this reaction, the leaving group properties of R determining the direction of the cleavage. The crystal and molecular structures of compounds 2a and 2f were determined by X-ray diffraction studies. Ex0 positions were found for the N-Me and P-R groups. The isomers with the R group in the endo position are also present in solution in small amounts, as detected by NMR spectroscopy. Isomer interconversion by P inversion is slow on the NMR time scale. Compounds 2a, 2b and 2f were oxidized with elemental sulfur and selenium to give the monosulfides and selenides, respectively (2aS, 2aSe, 2 bS, 2bSe, 2fS, 2fSe Tertiary phosphanes R3P are versatile ligands in coordination chemistry. Indroduction of functional groups in their organic substituents R can be used as a method to modify the properties of the ligands and of the complexes derived therefrom. The phosphanes can, for example, become (P,N)-ambi-or polydentate in nature, as tertiary amine functions become part of the organic framework [']. Owing to the hydrophilic nature of these amine functions, such ligands and their complexes will become soluble in water and other polar solvents.An example in case is 1,3,5-triaza-7-phospha-adamantane (TPA)L2], which is known to be a suitable "soft" P-donor for low-valent transition with a small cone angle at the phosphorus atom, but also a "hard" ligand for metals in higher oxidation stated4]. It can be integrated into hydrogen-bonding networks based on its three tertiary amine functions, and it is easily solvated. The molecule is a strong nucleophile and forms both phosphonium and ammonium cations if treated with acids or alkyl hali d e~ [~]...