Coordination complexes, Cu

The electrochemical behavior of tetracoordinated Cu(i) complexes (i.e., Cu(dpp)2-based cores) is well established.193,941 The reversible redox potential for the Cu(ii)/ Cu(i) transition is around 0.6-0.7 V versus SCE. This relatively high potential underlines the stability of the 4-coordinate Cu(i) complexes relative to their Cu(n) counterparts. The redox potential of pentacoordinated copper complexes 84 86 is observed in a much more cathodic range. For example, for the 5-coordinate complex Cu(l, dap)2+/+ (dap = 2,9-di-p-anisyl-l, 10-phcnanthrolinc), in which the terpy fragment of the ring is bound to the metal, the redox potential is -0.035 V. This potential shift when going from tetracoordinated to pentacoordinated copper systems is due to the better stabilization of the Cu(ii) state, thanks to the presence in the coordination sphere of live donor atoms. 

The most detailed studies of the phenomenon are confined to ammoniacal solutions. In the case of ammonia medium the familiar coordination complexes Cu(NH3) + and Cu(NH3)2 are formed, leading to selective removal of metal and causing the damage. In ammoniacal solutions traces of phosphorus (about 0.004%) increase the susceptibility to SCC. Other elements such as As and Sb have similar effects. These elements in trace amounts in the alloy produce precipitates at the grain boundaries and make the grain boundary region more anodic to the grain bodies. 

Figure 6 A view of showing the ID water strand hosted by ID coordination polymers in (c) [Cu(L49)Cl] H20, 66, and (d) [Cu(L44)Cl] H2O, 67. A perspective view of the single water chain hosted by hydrogen-bonded coordination complex [Cu(L50)(phen)] 2H2O, 68 (f).

The multidrug resistance (mdr) reversing effect of the new phenothiazine complexes were tested on mouse T cell lymphoma cell lines. Trifluoperazine (TFP) was much more effective at the same concentration than verapamil. The efficacy of some metal coordination complexes [TFP-Cu(ll) and TFP-V(IV)] exceeded the action of TFP alone. Chlorpromazine (CPZ) or CPZ-Pt(ll) complex had the same or less effect than verapamil or promethazine (Pz) used as a control. 

Frenking s group showed that the Group 11 isocyanides M—NC (M = Cu, Ag and Au) are less well bound compared with the corresponding cyanides M—CN [276]. They also studied CO coordination on Cu, Ag+ and Au with Au(CO)2 being the most stable of all Group 11 dicarbonyl complexes [281]. Vaara et al. demonstrated the importance of relativistic effects in the 13-C NMR nuclear shielding constant in... 

Two types of FeQl) dithiocarbamates are reported. To the first type belong the complexes Fe(R2powder diffraction pattern shows the ethyl compound to be isomorphous with the five-coordinated, dimeric Cu(II) complex (18), so it is to be expected that the fifth Fe-S bond is longer than the other four. Further details about Fe(R2C fc)2 are scarce, as the compounds are air-sensitive and rapidly oxidise to Fe(III) complexes. 

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