Copper

Abstract

This chapter reviews the literature during 2007 on the chemistry of copper. HighlightsThe homoleptic species [Cu(Z 2 -C 2 H 4 ) 3 ] + and [Cu(Z 2 -P 4 ) 2 ] + have been characterised. 1e The consequences of symmetric vs. asymmetric coordination of the metal centres in dicopper(I) complexes have been explored. 3a-e Among mixed-valence heteronuclear chemistry, a giant M 45 cluster containing Cu I , Cu II , Mn II , Mn III and Mn IV has T d symmetry and an S = 51/2 ground state. 7g 'Catalytic promiscuity' has been revealed in a dicopper(II) complex, 17e while unique rectangular bridging by chloride occurs in a tetracopper(II) cluster. 22f This has been a vintage year for copper(III) chemistry, with the isolation of hitherto elusive Cu III intermediates in organic conjugation addition reactions 27a-c and of heterobimetallic {Cu III (m-O) 2 M II } species. 27e Copper(I) chemistry Mononuclear speciesCoverage here follows the Group numbers of the donor atoms in the ligands of primary interest. Complexes [CuL(NCMe)][BF 4 ], where L is an N-heterocycle, catalyse the diboration of styrene via bis(catecholato)diboron; DFT calculations indicate intermediates with trigonal CuNB 2 coordination. 1a The mechanism of copper(I)-catalysed azide-alkyne cycloaddition involves formation of Cu-CRCR complexes. 1b A similar reaction enables the template syntheses of [2]-and [3]-rotaxanes, 1c and a copper(I) triazolide complex has been isolated from the cyclisation step. 1d The [Cu(Z 2 -C 2 H 4 ) 3 ] + and [Cu(Z 2 -P 4 ) 2 ] + ions are stabilised by [Al{OC(CF 3 ) 3 } 4 ] À . 1e63 Cu and 65 Cu NMR spectroscopy is proving useful in the characterisation of copper(I) complexes with N and P-donor ligands. 2a-c DFT calculations suggest that copper(I) prefers a mixture of hard and soft ligands; maximum hardness for [Cu(NH 3 ) n (PH 3 ) 4Àn ] + was found for n = 1. 2d Excited state structural dynamics have been studied in an MLCT state of [Cu(2,9-Me 2 phen) 2 ] + , 2e-f while equilibration among three MLCT states has been found in similar complexes with bulkier substituents. 2g Copper(I) complexes with phen-type ligands tethered to a cyclotriphosphazene platform have been characterised. 2h Rotaxanes and pseudorotaxanes assembled from bis(phen)copper(I) species have been examined as molecular machines. 2i-k The cation in [Cu(PhNO) 3 ][PF 6 ] is implicated in the copper(I)-catalysed allylic amination of olefins. 2l Redox activity, absent in two-coordinate copper(I) complexes with His-His, appears with coordination of a third ligand. 2m A new geometric index for four-coordination is proposed on the basis of the structures of