The solid-state mechanochemical method was proved to be a fast, simple, and efficient route to the synthesis of heterometallic [Au(CN)(2)]-based coordination polymers. Thus, a series of mixed-metal complexes, such as KCo[Au(CN)(2)](3), KNi[Au(CN)(2)](3), Cu(H(2)O)(2)[Au(CN)(2)](2), and Zn[Au(CN)(2)](2), was obtained by grinding stoichiometric amounts of K[Au(CN)(2)] and transition metal(II) chlorides. This solid-state method rapidly yields pure dicyanoaurate-based compounds, also in cases when the aqueous solution synthesis leads to an unseparable mixture of products. In addition, in some cases, the solid state reaction was faster than the corresponding solvent-based reaction. This mechanochemical method can be applied also to main group metals to obtain various cyanoaurate-based heterometallic coordination polymers, such as Me(2)Sn[Au(CN)(2)](2) and Ph(3)Sn[Au(CN)(2)]. For the 2:1 mixture of K[Au(CN)(2)] and Me(2)SnCl(2), the dramatic enhancement of the reaction rate by the presence of a minor amount of water was noticed. In Ph(3)Sn[Au(CN)(2)], as was revealed by single-crystal X-ray diffraction, each Ph(3)Sn unit is linked to two others by two Au(CN)(2) bridges via Sn-N bonds to form an infinite cyanide-bridged chain. There are no Au···Au contacts between the chains due to the sterical hindrance of the phenyl groups. A dehydrated blue Co[Au(CN)(2)](2) complex was obtained during grinding or heating of the moderate-pink Co(H(2)O)(2)[Au(CN)(2)](2) complex. This complex displays a vapochromic response when exposed to a variety of organic solvents, as well as water and ammonia vapors.

The achiral 4,6-bis(diphenylphosphino) phenoxazine (nixantphos) ligand was used to synthesize a gold(I) complex, [Au2(nixantphos)2](NO3)2, containing a 16-membered [Au2(nixantphos)2](+2) cationic ring in a chiral figure-eight conformation. The single crystal X-ray diffraction analysis of [Au2(nixantphos)2](NO3)2.3MeOH.H2O (1) and [Au2(nixantphos)2](NO3)2.4MeCN (2) revealed a solvent-assisted spontaneous resolution of the [Au2(nixantphos)2](NO3)2 complex. By changing the nature of the solvent, homochiral hydrogen bonded helices (1) and heterochiral hydrogen bonded monomers (2) were obtained. Multinuclear NMR spectroscopy showed the evidence of chemical exchange phenomenon related to the interconversion of the enantiomeric skeletons of the 16-membered macrocycle in solution. The existence of the Au...Au aurophilic interaction was confirmed by the analysis of the spin-system in the (31)P NMR spectrum.

We synthesized and structurally characterized the first cyanoaurate-based organotin polymer Me(3)Sn[Au(CN)(2)] (1), which exhibits unusual ion-exchange properties. In the structure of 1, the void space of the 2D grids formed via Au...Au bonding is filled by arrays of zigzag chains joined by weak Au...Au interactions. Interestingly, the practically insoluble polymer 1 shows unusual ion-exchange properties. The polymer Me(2)Sn[Au(CN)(2)](2) (2) was obtained in the metathesis reaction of 1 with Me(2)SnCl(2). Compound 2 displays cyanide-bridged uninodal four-connected 3D nets with 6(5).8 topology corresponding to the CdSO(4) prototype. Interestingly, 2 can be converted back into 1 by metathesis with Me(3)SnCl. Moreover, we performed a series of metal-exchange experiments in which 1 was soaked in aqueous solutions of bivalent transition-metal cations M(2+) (M = Co, Ni, Cu, Zn). As a result, 1 was completely converted into transition-metal cyanoaurates. To our knowledge, this represents the first study revealing the metal-exchange properties of a cyanoaurate-based heterometallic polymer.

The nonporous gold(I) diphosphine complex [Au(2)(cis-dppe)(2)](NO(3))(2) [1, cis-dppe = cis-1,2-bis(diphenylphosphino)ethylene] is robust enough to trap guests, but at the same time, it is flexible enough to allow guest release without destruction of its crystal lattice. This nonporous gold(I) compound 1 is also efficient at capturing and releasing carbon dioxide in a controlled manner.

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