Metallophilic bonding

In the crystal, most trinuclear carbeniate complexes are known to be stacked with close aurophilic interactions, and organic 7r-acids can be intercalated into these stacks.252 Similar intercalation takes place with the cations of simple silver and thallium(i) salts. The cations become attached to form polymetallic core units through metallophilic bonding. With the trinuclear silver pyrazolates, both metal and ligand exchange have been observed to give new stacks of trinuclear units.254... 

Catalano et al. reported the synthesis and characterization of a new series of Pd°-based metallocrypates that bind Tl1 ion in the absence of attractive ligand interactions through metal-lophilic connections. The cationic species have been characterized by a variety of methods and have considerable stability. From the solid-state structural data it is apparent that interaction of the metal atoms with one another is the dominant bonding interaction within the metallocryptate cavity. The characterization of complexes supports the concept of metallophilic behavior as a fundamental component of bonding in closed-shell systems. These materials may ultimately serve as prototypical systems for detection of closed-shell ions 946... 

In short, it is clear that gold makes an essential contribution to metallophilic interactions. Thus, the design of synthetic strategies to prepare systems with these bonds of unique versatility and flexibility must include gold as an essential building block. 

A particular case is that of d -d secondary interactions, first identified in gold compounds and described as aurophilic attraction [78-80], later generalized as metallophilic attraction [81]. This leads to supramolecular self-assembly in many gold compounds, especially when associated with three-center Au- -C Au bonds, and can be also found in other d metal compounds, such as silver, gold, and thallium complexes. Such supermolecules are illustrated by the quasi-cyclic pen-tamers Au5(Mes)5 and Cus(Mes)5, 33, and the tetramer Ag4(Mes)4, 34 [82]. 

The extent of selective metallophilicity of microorganisms is beUeved to be determined by a number of factors, including (1) the selective direction of motion of the colloidal particles relative to microorganisms, and (2) the nature and strength of the chemical bonding of particles on the surface. Covalent bonds to the surface are predominate. 

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