Luminescence and metal-metal interactions in binuclear gold(I) compounds

Abstract

2145schematically shown in Figure 3, a simple reorientation of the copper square-pyramidal moieties might suffice, in principle, to bring about the dimer -+ uniform-chain transformation without any dramatic change in the geometry of the first coordination sphere around the metal centers or in the occupancy of space. An arrangement of dimers similar to that depicted in Figure 3 exists along the c axis of the title compound, and we also note that competition between neighboring copper atoms for bonding to apical chlorine atoms has been shown to be a relevant factor in determining the crystal chemistry of chloride-bridged chain compounds of copper(II).i6i8 In any event, the precise nature of the low-temperature phase of the present compound and the mechanism or reason for the postulated transition are interesting problems that remain open to further studies, particularly lowtemperature X-ray studies.In conclusion, the results presented in this paper confirm the utility of synthesizing new halide-bridged copper(I1) compounds with heterocyclic ligands as appropriate candidates for studying the impact of structural phase transitions on the magnetic int e r a c t i o n~.~~ As more of these types of systems are prepared and studied, it will hopefully be possible to provide some insight into the mechanisms that underlie the structural changes in them. This problem, of course, is also relevant to the family of distortion models typified by the spin-Peierls instability, Le., those in which changes in lattice energy and changes in exchange energy are of comparable magnitude.Registry No. Cu2L2CI2.2CH3OH, 120232-12-4; 8-aminoquinoline, 578-66-5; salicylaldehyde, 90-02-8. Supplementary Material Available:Tables SI-SIII, listing angles and distances associated with the aromatic rings, thermal parameters, and the derived hydrogen positions (3 pages); a table of calculated and observed structure factors (1 1 pages). Ordering information is given on any current masthead page. (35) See paper by L. J. de Jongh in ref 2a.[Au(dppm)],(BF,), is phosphorescent in solution ( A, , , = 593 nm, T = 21 ps, = 0.31). An SCF-Xa-SW molecular orbital calculation carried out on the model compound [Au(H2PCH2PH2)]?+ found the Au-Au u* HOMO to have 78% Au character. Of this, 41% is from the 6s orbital and 41% is from the 5d,z orbital. The metal-metal interactions are discussed. The 293-nm (e 21 OOO M-' cm-I) absorption band is attributed to a u(p,) -a*(s,dg) transition. The A d 2 emissive state appears to be "Ju*)(a) (C2h symmetry). The binuclear Ad2 compounds [A~(dppm)]~Cl~, [ A u ( C H~)~P P~~]~, [~-Bu,N],[Au(S,C=C(CN)~)],, [Au-(CH,P(S)Ph2)]2, and [AU(S~CNE~,)]~ are luminescent in the solid state at room temperature with A,, ranging from 465 to 593 nm and excited-state lifetimes ranging from 1 to 24 1 s . (Ph3PAu),(S2C=C(CN),) is luminescent at 77 K but not at room temperature. Mononuclear Ph3PAuCI luminesces in the solid state ( A, , , = 491 nm, 7 = 3 ps).

The 3[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

“…The dmmp ligand, on the other hand, was reported to form trinuclear Au I complexes with a Au···Au···Au angle of 1368. [39] In view of the advantageous structural feature of the ligand dcpm [11,12,32] over dppm [7,8] in spectroscopic studies on dinuclear [M 2 A C H T U N G T R E N N U N G (P^P) 2 ] 2 + (P^P = phosphine ligand, M = Au I , Ag I ) systems, we prepared the cyclohexyl analogue of the dpmp ligand, dcmp, which is optically transparent in the spectral region of interest to the spectroscopic properties of polynuclear d 10 -metal complexes, and should be able to bridge three two-coordinate d 10 -metal ions in a linear-array fashion.…”

“…[2][3][4][5][6] A notable example in this area is [Au 2 -A C H T U N G T R E N N U N G (dppm) 2 ] 2 + salts (dppm = bis(diphenylphosphino)methane), which are strongly emissive in the visible spectral region (l max = 570 nm with an emission lifetime of 21 ms and emission quantum yield of 0.23 in CH 3 CN) and behaves as a photoreductant capable of cleaving C À X bonds of benzyl halides. [7,8] It is now becoming a general phenomenon that the photoluminescent properties of polynuclear d 10 -metal complexes are sensitive to subtle changes, for instance, exposure to volatile organic compounds and close contact of anion/solvent molecule(s) with metal ion(s) in the crystal structure. [9][10][11][12][13][14][15][16][17][18][19][20][21] Understanding the emissive excited states and the factors governing the excited state properties of polynuclear d 10 -metal complexes are essential for their eventual uses as sensors [22,23] and in molecular light-emitting diodes.…”

“…[24][25][26][27] The 3 A C H T U N G T R E N N U N G [nds*A C H T U N G T R E N N U N G (n+1)ps] excited state has enhanced metalmetal bonding than in the ground state and this has often been invoked to account for the anomalous Stokes shift between the absorption and emission spectra of polynuclear d 10 -metal aggregates. [6,8,18,[28][29][30][31] However, spectroscopic evidence for emission from such excited states is sparse, partic- (7) were prepared and their structures were determined by X-ray crystallography. Complexes 2-4 display a high-energy emission band with l max at 442-452 nm, whereas 1 and 5 display a low-energy emission with l max at 558-634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the 3 2 ] 3 + , whereas the latter is attributed to an exciplex formed between the …”

Structure of Au2[S2CN(C2H5)2]2, bis(diethyldithiocarbamato)digold(I)

“…Although the structural characterization of a dinuclear Au n system containing an Au--Au bond has not been achieved, Burmeister and co-workers have observed these species at low temperatures (Calabro, Harrison, Palmer, Moguel, Rebbert & Burmeister, 1981). As part of our studies we have been investigating the luminescence of Au systems which contain either Au--Au bonds or linear chains of Au atoms in the solid state (King, Wang, Khan & Fackler, 1989). A portion of this work has dealt with the dinuclear Au I complex containing diethylidithiocarbamate, Au2[S2CN(C2Hs)2]2.…”

Structural and Photophysical Properties of (Phosphane)gold(I)‐Decorated 4,4′‐Diethynyl‐2,2′‐bipyridine Ligands

“…The presence of short (≈3.00-3.20 Å) Au...Au contacts in the solid state is thought to be fundamental to emissive behaviour. [3,[9][10][11] By combining phosphine and alkyne metal-binding domains at a gold(I) centre, one gains significant scope for the design of macromolecules: [12] rigid-rod P-Au-C≡C-domains and a wide range of readily accessible mono-, bi-and polydentate phosphine ligands containing sp 3 hybridized P atoms combine with a tendency for gold atoms to aggregate (so-called 'aurophilicity'). [13][14][15]16] Of the 215 compounds in the CSD (CSD v 5.3 with May 2009 updates, Conquest v. 1.11) [17] possessing R 3 PAuC≡C units, only 19 [9,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] exhibit intermolecular aurophilic interactions resulting in onedimensional Au...Au bonded polymers.…”