Tetranuclear linear

Mo(Tp )(CO)3(r 3-allyl)] requires higher potentials for a generally irreversible oxidation to proceed. The product of oxidation of [Mo(Tp )(CO)3l] with oxygen was a tetranuclear linear molybde-num(V) complex with terminal metal ions coordinated to Tp ligands and inner molybdenum(V) ions surrounded exclusively by oxygen donors.115... 

All three M+ ions are known to form compounds with the unusual digonal linear coordination (see also section 4.9.7), though this is most common for gold. As a result, complexes R3PMX of copper and silver are normally di-and tetranuclear species with 3- or 4-coordinate metals, while the gold analogues are 2-coordinate monomers. This is the reverse of what would be expected on steric grounds [13, 14],... 

The demonstration of the formation of a hexanuclear zinc complex with the S-donor ligand 2-aminoethanethiolate, containing Zn3S3 and Zn4S4 cyclic units, contributes to the building up of a pattern of polynuclear complex formation based on coordination preferences of the metal ions involved (320) - reaction of Zn2+ with salicylideneamino ligands and pyrazine can give linear tetranuclear complexes (321). Another hexanuclear zinc complex appears in the section on supramolecular chemistry below (Section VII.D). 

A few linear tetranuclear complexes of ligands related to dpa have been structurally characterised, namely [Ni4(phdpda)4] (phdpda = dianion of A-phenyldipyridylamine),39 [Cu4(dphip)4]2 + (dphip = anion of 2,6-bis(phenylamino)piperidine),37b and [Cr4(dpf)4Cl2]2+ (dpf = anion of bis(2-pyridyl)formamidine),38 but no pertinent electrochemical investigation is available. 

Isocyanides are long known as ligands able to afford linear polynuclear complexes. This is, for example, the case of the trinuclear [Rh3 (C6H5CH2NC)12I2]3 +, 46 and tetranuclear [Rh4 NC(CH2)3NC 8Cl]5 +, 47 complexes, the electrochemical behaviour of which is, however, unknown. 

The reaction ofnPF6 with [NBu4][Au(C6F5)2] and 4,4 -bipyridine, inTHF, gave the pale yellow complex [ Tl(4,4 -bipy) 2 Au(C6F5)2 2] 68, which also exhibits a 2D network (Figure 4.20a) [69]. In this case almost linear tetranuclear units, [ ... 

The ionic components are associated in guest-linear tetranuclear units [Au... 

The linear trinuclear cation (100) and the tetranuclear cations (101) to (103)448-450 (Table 52) exist with mononuclear complexes in aqueous ethylenediamine buffer solutions in which equilibrium has been established by the catalytic effect of Cr2+ and charcoal under well-specified conditions.358 The cations were separated by ion exchange chromatography and fractional crystallization, and isolated as various salts (Table 52). The tetranuclear (rhodoso) compound (104)4S1 has been reprepared448 by a modification of Pfeiffer s method. 

A trinuclear complex, Cr,(en)s(0H)4 if, and three tetranuclear complexes with the common formula Cr4(en) (OH)(1h have been isolated as salts and characterized. The structures of the trinuclear and one of the tetranuclear complexes have, however, not been established, although cleavage experiments and spectral properties suggest that they both have a linear structure e.g., the most probable structure for... 

---