Copper complexes coordination number

The properties of copper(Il) are quite different. Ligands that form strong coordinate bonds bind copper(Il) readily to form complexes in which the copper has coordination numbers of 4 or 6, such as tetraammine copper(Tl) [16828-95-8] [Cu(NH3)4], and hexaaquacopper(Il) [14946-74-8] [Cu(H,0),p+ ( see Coordination compounds). Formation of copper(Il) complexes in aqueous solution depends on the abiUty of the ligands to compete with water for coordination sites. Most copper(Il) complexes are colored and paramagnetic as a result of the unpaired electron in the 2d orbital (see Copper... 

The inner 3d orbital of copper(I) is completely filled and the compounds of copper(I) are almost colorless. On the other hand, most copper(II) complexes are colored and paramagnetic as a result of the unpaired electron in the 3d orbital, and the copper has coordination numbers of 4 or 6 [16]. 

The kind of electronic spectrum of copper (II) chloroform extract provided in Figure 11.9 is typical for complex compounds of copper with coordination number 6. 

Despite the weak basicity of isoxazoles, complexes of the parent methyl and phenyl derivatives with numerous metal ions such as copper, zinc, cobalt, etc. have been described (79AHC(25) 147). Many transition metal cations form complexes with Imidazoles the coordination number is four to six (70AHC(12)103). The chemistry of pyrazole complexes has been especially well studied and coordination compounds are known with thlazoles and 1,2,4-triazoles. Tetrazole anions also form good ligands for heavy metals (77AHC(21)323). 

Figure 15.2 (p. 412) shows the structure of the chelates formed by copper(II) with these ligands. Notice that in both of these complex ions, the coordination number of copper(II) is 4. The central cation is bonded to four atoms, two from each ligand. 

Coordination number The number of bonds from the central metal to the ligands in a complex ion, 409,412t four-coordinate metal complex, 413 six-coordinate metal complex, 413-414 Copper, 412 blister, 539... 

The neutral 3 dx metallocenes are thus known for x = 3 — 8, but the d9 copper complex has thus far resisted preparation, and the d2 titanocene has been found (54) to be both diamagnetic and dimeric, and is therefore excluded from consideration here. A number of cationic species, corresponding formally to Ti(Cp)2+, and V(Cp)2+, systems are however well known, but it seems very probable that these do not possess pseudo-axial symmetry (see (41) for further discussion), and very recently it has been demonstrated (55) that stable V(Cp)2+ complexes cannot be isolated without the coordination of an additional ligand to the metal. The parent systems are therefore limited to V(Cp)2, Cr(Cp)2, Mn(Cp)2, Fe(Cp)2, Co(Cp)2, and Ni(Cp)2 and the cationic species to Cr(Cp)2+, Fe(Cp)2+, Co(Cp)2+, and Ni (Cp)2+> and the d-d spectra of these systems are now considered individually. 

Mapsi et al. [16] reported the use of a potentiometric method for the determination of the stability constants of miconazole complexes with iron(II), iron(III), cobalt(II), nickel(II), copper(II), and zinc(II) ions. The interaction of miconazole with the ions was determined potentiometrically in methanol-water (90 10) at an ionic force of 0.16 and at 20 °C. The coordination number of iron, cobalt, and nickel was 6 copper and zinc show a coordination number of 4. The values of the respected log jSn of these complexes were calculated by an improved Scatchard (1949) method and they are in agreement with the Irving-Williams (1953) series of Fe2+ < Co2+ < Ni2 < Cu2+ < Zn2+. 

The nitrogen in the ammonia and the oxygen in the water are the donor atoms. They are the atoms that actually donate the electrons to the Lewis acid. The coordination number is the number of donor atoms that surround the central atom. As seen above, the coordination number for Cr3+ is 6. Coordination numbers are usually 2, 4 or 6, but other values can be possible. Silver (Ag ) commonly forms complexes with a coordination number of 2 zinc (Zn2+), copper (Cu2+), nickel (Ni2+), and platinum (Pt2+) commonly form complexes with a coordination number of 4 most other central ions have a coordination number of 6. 

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