D” metal ions

The structures below show a hydrated d-metal ion. Draw the structure of the conjugate base of this complex. 

Much research focuses on the structures, properties, and uses of the complexes formed between d-metal ions acting as Lewis acids and a variety of Lewis bases, partly because they participate in many biological reactions. Hemoglobin and vitamin B12, for example, are both complexes—the former of iron and the latter of cobalt (Box 16.1). Complexes of the d-metals are often brightly colored and magnetic and are used in chemistry for analysis, to dissolve ions (Section 11.13), in the... 

Because water is a Lewis base, it forms complexes with most d-block ions when they dissolve in it. Aqueous solutions of d-metal ions are usually solutions of their HzO complexes Fe2+(aq), for instance, is more accurately [Fe(H20)6]2+. Many complexes are prepared simply by mixing aqueous solutions of a d-metal ion with the appropriate Lewis base (Fig. 16.16) for example,... 

Syntheses and luminescence studies of mixed-metal gold(I)-copper(l) and -silver (I) alkynyl complexes. The tuming-on of emission upon d metal ion encapsulation. Dalton Transactions, 1830-1835. 

In this section, we describe the behavior of the different metal ions. It may be useful to summarize first some terminologies used to describe the electronic structure. The ground state of the free-ion configuration depends on the maximum values of L = Y mi and S = mg. It is indicated by where X= S, P, D, F depending on the L value equal to 0,1,2,3, respectively. Therefore, a d metal ion has L=2 and S=l/2 and thus a configuration, etc. Other examples are reported in Table I. 

METAL ION a UNCOMPLEXED CARRIER [Pg.296]

Many flavoproteins contain, besides the flavocoenzyme, also metal ions as prosthetic groups The study of the interaction between free flavoquinone and d-metal ions is, therefore, of biological interest. In aprotic polar solvents weak complexes are formed Bidentate chelates are formed involving N(5) and the carbonyl... 

As typical examples of complexes with bidentate RS(CH2) SR and tridentate [RS(CH2) ]2S we may quote here a series of mononuclear Ru compounds which have been prepared and characterized by Chatt et aV Another example of a tridentate ligand is trithiane, which forms complexes with Ag1 and Hg11.9,10 More complexes are given in a review concerned with chelating dithioether complexes of d% metal ions.11. 

Use information in Table 16.4 to name each of the following complexes. Determine the coordination number and oxidation number of the d-metal ion ... 

Figure 10.37 (a) Orbital energy diagram for an octahedral d metal ion. (b) Effect on the relative energies... 

This last section deals with a few examples of the formation of self-assembly structures from lanthanide complexes, which are formed by using transition metal ions. This area of research is very novel and relatively few examples have been developed to date. While the lanthanide ions have been used to mediate the formation of supramolecular structures, such as helicates, many of which can have both/-/ mdf-d metal ions, etc. the focus here will be on the use of lanthanide complexes and ligand structures similar to those described above [170-173]. 

Although monodentate triazenide ligands were first proposed (erroneously) by Meunier in 1900 150,152) for the copper(I) complex Cu(PhNNNPh), this mode of coordination was not finally confirmed until 1976 when Brown and Ibers 21, 22) reported the X-ray crystal structure of c/s-Pt(PhNNNPh)2(PPh3)2 C6H6 (Fig. 1). Monodentate triazenide ligands remain relatively rare and are mainly confined at present to the four-coordinate d metal ions, Rh(I), Ir(I), Pd(II), and Pt(II). To date only six examples have been characterized by diffraction methods (see Table I). In some of these, notably trans-PtH(p-tol-NNN-tol-pXPPh3)2, there is a short nonbonded contact (2.91 A) between the metal and the terminal (N-3) nitrogen atom 109). Variable-temperature proton NMR studies (see Section... 

The influence of each oxidation state on the NMR spectra is quite different. Copper(l) is a d metal ion and has no unpaired electrons. Hence, its influence is limited to directly bound ligand atoms whose nuclei can couple to the copper nucleus and experience the influence of its quadrupole moment. This approach has not been exploited yet in proteins. In any case, the relaxation features of nearby nuclei are not greatly affected, and standard NMR experiments can be performed on... 

So far, for the highly oxygen-sensitive Co -forms of cobalt-corrinoids (such as Co -cobalamin, (6)), information from X-ray analysis on their three-dimensional structure is not available. However, in these strongly nucleophihc, highly reduced cobalt complexes, the diamagnetic Co -center (a d metal ion, isoelectronic with a Ni"-ion) presumably is ligated by the corrin ligand only, in a tetracoordinated, nearly square-planar fashion. As a consequence, the Co -forms of complete corrins would have to be base-off, that is, the nucleotide function would not be attached to the central cobalt ion. 

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