Copper complexes homoleptic structures

Examples of silver(l) alkyl and alkenyl (including aryl) complexes have been known from as early as 1941 6-9 however, the number of examples is fairly limited with respect to that of the heavier congeners, copper(l) and gold(l). Such a phenomenon can readily be attributed to the relatively low stability of this class of complexes, both photochemically and thermally. Simple homoleptic alkyl and alkenyl complexes of silver(i) are known to be very unstable under ambient temperature and light, and successful isolation of this class is fairly limited and mainly confined to those involving perfluoroorganics.10 The structures and the metal-carbon bond-dissociation energies for... 

Dinuclear complexes were obtained by reacting some binary copper(I) and silver(I) homoleptic pyrazolate complexes with neutral ligands. The trimeric [Cu(dmpz)]3 (23) readily reacted with phen or RNC (R = cyclohexyl) to give the doubly bridged species [(phen)Cu(/i-dmpz)2Cu(phen)], 32, (49) or [(RNC)Cu(/t-dmpz)2Cu(RNC)], 33 (50). The dimeric nature of 32 was argued from its spectroscopic and chemical properties, while 33 was characterized by an X-ray crystal structure analysis (50). 

Another source of interest came from biochemistry. Research on the blue copper proteins revealed unusual electronic properties (redox potential and kinetics, EPR and optical behavior) that were suspected of arising from interaction of the copper ion with a thioether group from methionine [7]. While crystallographic studies established a weak interaction (Cu -- - S 2.9 A) [8,9,10], its influence on the electronic properties of the Cu site is now considered questionable. Nevertheless, the controversy regarding the blue eopper proteins, like the analogy to phosphines, served to focus attention on the broad issue of how thioether coordination affects the electronic structure of transition metal ions. Homoleptic thioether complexes provide the best way of assessing these consequences, since no other groups obscure the effect of thioether coordination. 

More systematic insight into the coordinatirMi of diphenylplatinum complexes to d metals was obtained using the simple a-diimine ligand 2,3-bis(2,6-dichlorophe-nylimino)butane (NISI). The complex [(NN)PtPh2] reacts with half an equivalent of MOTf (M = Cu, Ag) to form homoleptic 2 1 cationic complexes in which the coinage metal is bound to the diphenylplatinum unit in a type III fashion (Scheme 15, top). The X-ray crystal structure of the copper cation is presented in Figure 1. 

The trinuclear [ClCu Zr2(OPr )9 ] has the [CuZr(jU3-OPr )2(jU,-OPr )3] core similar to the analogous titanium complex. The homoleptic Cu(i)Zr(iv) complex has a different structure [Cu2Zr2(OPr )io] containing the confacial bi-octahedral Zr2(OPr )9 unit into which the Cu2(/u,-OPr ) group is inserted by the copper atoms bridging with terminal isopropoxo ligands on each Zr. The (/i-OPr ) Cu(/i-OPr ) system has a hnear O-Cu-0... 

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