Tetranuclear square planar

For tetranuclear cluster complexes, three stmcture types are observed tetrahedral open tetrahedral (butterfly) or square planar, for typical total valence electron counts of 60, 62, and 64, respectively. The earliest tetracarbonyl cluster complexes known were Co4(CO)22, and the rhodium and iridium analogues. The... 

Another remarkable example of a mercuracarborand halide adduct has been obtained by reaction of the octamethyl tetranuclear derivative 165 with [NMe4]F. This reaction affords complex [165-F]- in which the fluoride is coordinated to the four mercury centers in an approximate square-planar arrangement (Equation (57)). The Hg-F distances, which range from 2.56 to 2.65 A, are slightly longer than those found in [163-/i2-F]2. The 9Hg NMR resonance of the complex indicates coupling to the fluorine atom with 1Jug-F = 698 Hz.215... 

Stang et al. [94JA4981, 9403776, 95JA1667, 95JA6273] described the self assembly of a series of unique cationic, tetranuclear, Pd(II)- and Pt(II)-based macrocyclic squares (e.g., 25), utilizing different bidentates as the sides of these structures. The similar self-assembly complexation of dipyridyl porphyrins by cis- and tran.v-substituted Pd(II) or Pt(II) ions possessing square planar coordination afforded multiporphyrin arrays with a square... 

Other octanuclear lanthanide oxoalkoxides are known. They are also based on tetranuclear units arranged around square planar 0x0 ligands such as in [Erg( U4-0)(/i3-OH)i2(thd)io] (Boeyens and De Villiers, 1972 Pigure 106) and [Pr8(M4-C>)4(OC2H40Me)i6(OPMe3)2] (Hubert-Pfaizgraf et al., 1997). 

Silver dithiocarboxylato complexes also tend to form dimers, polymers and clusters with various geometries around the silver atoms [109-111]. For example, in the tetranuclear silver clusters 55 and 56 bearing dithiocarboxylato ligands, four silver atoms are in a roughly square-planar array and a highly distorted tetrahedral array, respectively (Fig. 13) [32]. In these complexes, each sulfur atom is attached to one or two silver atoms, respectively. 

Tetranuclear clusters frequently contain a tetrahedral or square-planar M4 moiety. Generally, the metal atoms or ions are bridged by ligands. Nevertheless, a direct metal-metal interaction seems to be present, but sometimes rather weak. 

Tetranuclear copper complexes have tetrahedral, square-planar, or butterfly structures. The compound Cu4 (Pr 0)2PS2 4 has a distorted tetrahedral skeleton of the metal atoms with one sulfur atom symmetrically bonded to two copper atoms, while the other sulfur atom forms a bond with the third copper atom. Copper and silver form many clusters containing alkyl and aryl ligands (See Chapter 4). The complex Cu4(CH2SiMe3)4, like Cu4 N(SiMe3)2 4, has a square-planar structure with bridging alkyl ligands. In the alkyl compound, in contrast to the amide one, there are Cu —Cu bonds. 

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