Complexes of group 11 Cu, Ag, Au

Together with platinum(II) complexes, also complexes of group 11 metals have been intensively studied for their luminescence properties, in particular dinuclear complexes of M(I) (M = Cu, Ag, Au), in which one or two dicarbene ligands coordinate in a bridging fashion the two metal centers. The formula of this type of complexes is exemphfied in Fig. 38. 

The formation of trinuclear complexes 2 -Ag, 2 -Cu, 2 -Au shows the tendency of group 11 metal ions to form linear, two-coordinate complexes. As a result, the metal centers of these complexes are not situated in a well-protected cavity as planned. 

Cationic Group 11 carbonyl complexes have been implicated in catalytic carbony-lation reactions of alkenes, arenes, alcohols, saturated hydrocarbons and aldehydes under acidic conditions [106]. While the mono- and di-carbonyls [M(CO)] and [M(C0)2] (M = Cu, Ag, Au) can be formed at atmospheric pressure of CO, only Cu(I) forms a tricarbonyl cation under such conditions [107]. Strauss and co-workers reported the observation of [Ag(CO)3] when a Fluorolube mull of Ag[Nb(OTep5)5] was subjected to 13 bar CO in an HP IR transmission cell [108]. 

Thin metalhc fihns play an important role in diverse fields of applications, with special emphasis on micro- and nanoelectronics for which the metals Al, Cu, Ag, Au, Ti and W are essential Additional fields of commercial interests are electrodes as well as reflective, corrosion-resistant, oxidation-resistant and abrasion-resistant coatings . Noble metals (periods 5 and 6 of groups 8-11 of the periodic table of the elements) are of special interest due to their manifold application in heterogeneous catalysis. Other metals used in specialized industrial applications or as components of more complex materials such as metal alloys are Ni, Pd, Pt, Ag and Au. For example, FePt-based nanostructured materials are excellent candidates for future high-density magnetic recording media . ... 

Group 11 metals show only one C—O stretching vibration at 2105 (Cu), 2160 (Ag), and 2110 (Au) cm after the surfaces are exposed to CO. Again, when comparing molecular complexes of these metals, Cu gives carbonyl complexes in its +1 oxidation state, (see 14.6.1.6), but only one example of a well-defined carbonyl complex of Ag is known and Au forms the carbonyl halo complexes Au(CO)Cl , and Au(CO)Br with an infrared absorption around 2160 cm , higher than in free CO. 

The solution chemistries of group 11 elements (Cu, Ag, Au) in oxidation state I are similar. Cul, Agl and Aul are strongly complexed with Cl- and hydrolysis is insignificant. While Ag solely exists as Agl, Cu occurs dominantly as Cull in oxygenated seawater and oxidation number 111 may be important for Au. Cull chemistry is dominated by carbonate complexation, while Aulll speciation in seawater appears (tentatively) to be dominated by mixed-l and chlorohydroxy complexes. 

Our group has studied another class of transition metal carbonyl complexes, namely, the positive ions M(CO)+ (M = Cu, Ag, Au n = l-4).ii Table 11 shows the optimized M+—CO bond lengths at the HF/II and MP2/II levels of theory. The calculated and experimental M+—CO first dissociation energies of the carbonyl ligand are also shown. The experimental values have been taken from the recent compilation of observed Dq(0 K) values by Armentrout using... 

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... 

The metal-carbene bond distances in this family of complexes (2.082 (2) A for Ag, 1.9124 (16) A for Cu, and 2.035 (12) A for Au) are within the range of reported values for typical group 11 metal NHC complexes (23). The metal carbene units are almost linear, with a C-M-C bond angle of 178.56 (13)°, 177.70 (9)°, and 177.7 (6)° for Ag, Cu, and Au, respectively. The imidazole units for 2 -Ag, 2 -Cu, 2Me Au exhibit structural parameters typically observed for coordinated NHC ligands. There are no inter- or intramolecular metal-metal interactions in these complexes. 

CuX(cycloheptyne)2] (Fig. 24), illustrating that such compounds are accessible under well-controlled coordination conditions. Organometallic, substituted alkynes [e.g., (OC)5ReC=CR, where R = Re(CO)s, SLMes] can be used as alkyne Jt-donor ligands to also afford group 11 (IB) bis(alkyne) complexes. Beck and co-workers (340) synthesized a series of [M (OC)5ReC=CR 2] complexes of Cu(I), Ag(l), and Au(I) (Fig. 25). 

Chiral Catalysts Containing Group 11 Metals (Cu, Ag, and Au). The most recent publications on the chiral copper catalysts are mainly dealing with those containing bis(oxazoline)-type ligands (Fig. 22). Cationic [Cu( Bu-BOX)] + complexes with OTf , [SbFe] , counterions catalyze Michael reactions, and various types of cycloadditions (292). Copper(II)-PYBOX complexes have been shown to catalyze enantioselective Mukaiyama aldol reactions (293). Similarly, bisoxa-zoline derivatives serve as ligands in the catalytic system prepared in situ from Cud) salts and are used for asymmetric peroxidation and enantioselective Meer-wein arylation of activated olefins (294). The copper-BOX-triflate complexes have found wide applications in cyclopropanation of alkenes (60), furans (295), and aziridination of alkenes (296). 

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