Influence of the group 11 metal on the emissive properties of complexes [M{(PR2)2C2B9H10}L]

Abstract

The metal atoms in group 11 complexes [M{(PR2)2C2B9H10}L] [R = Ph, (i)Pr; L = tertiary phosphane; M = Au, Ag, Cu] play an important role in the emissive properties of these compounds. The influence of the metal follows the order Au ≫ Ag ≥ Cu. The three-coordinated complexes are obtained from the reaction of [AuClL], [Ag(OTf)L], or [Cu(NO3)(PPh3)2] with the closo carborane diphosphane in refluxing ethanol. For L = PPh2NHPy, cleavage of the P-N bond and the formation of the monophosphane PPh2OEt are observed, depending on the metal and the nido carborane diphosphane substituent ((i)Pr or Ph).

The Chemistry of Gold

“…All the nuclearities from 4 to 13 gold atoms are known in homonuclear clusters, the latest is a regular icosahedron with a central gold atom [51,52]. This icosahedron may add in one of the corners three more gold atoms, forming a pendant tetrahedron and thus resulting in a 16-gold-atom cluster [53].…”

“…Dinuclear tetra-coordinate derivatives are achieved with tetradentate phosphines, including tetraphos or tris(2-(diphenylphosphino)ethyl)phosphine [211]. Mixed four-coordinate gold(I) complexes have been prepared with the 1,2-bis(diphenylphosphino)-o-carborane ligands and are of the type [Au{(PPh 2 ) 2 C 2 B 10 H 10 }(P-P)] þ [212] or with one nido and one closo diphosphine such as [Au{(PPh 2 ) 2 C 2 B 9 H 10 } {(PPh 2 ) 2 C 2 B 10 H 10 }] [51]. Figure 1.30 shows some of these complexes.…”

Substituent Effects on the Fluorescence Properties of ortho‐Carbor­anes: Unusual Emission Behaviour in C‐(2′‐Pyridyl)‐ortho‐carboranes

“…However, the vast majority of these compounds give very weak emissions; thus, these carboranes are considered (and have been reported for 4, [30] 7, [30] 12 [44] and 16 [20] ) as non-emissive. The influence of the substituents, Me, SH, SMe and SiMe 3 , on the photophysics of ortho-carborane is subtle, whereas the influence of the aryl groups, Ph, PPh 2 and 2′-pyridyl, is inevitably present with π-π* transitions and/or charge-transfer emissions.…”

“…[42] The phosphine 12 is also a precursor to many metal complexes as a bidentate donor ligand, and the closo-carborane cage can, however, be converted into a nido-carborane anion during the reaction. [43] Phosphine 12 itself has been reported to be non-emissive, [44] and luminescent metal complexes containing 12 as ligand have so far been limited to a silver complex. [45] The pyridylcarborane 13 has been used as a precursor to luminescent iridium complexes analogous to the ubiquitous Ir(ppy) 3 dopant emitter.…”

Gold: Oxidative Addition to Au(I)

“…1.7 Å vs. about 1.4 Å in benzene) and the rigidity of the cluster allows for precise directional control of both phosphorus atoms and puts their electron lone pairs in a geometry suitable for chelation of a metal center. P-M-P bite angles of approximately 90°with o-carborane-diphosphine ligands were observed for palladium [23,24], platinum [25] and coinage metal complexes [7,[26][27][28][29][30][31].Although o-carborane-diphosphines have been used as ligands for photochemical [32][33][34] or catalytic [35] applications, their coordination chemistry is by far less developed with regard to comparable, simpler diphosphines such as 1,2-bis(phosphino)ethane or 1,2-bis(phosphino)benzene. …”