Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Abstract

A series of tetragold(I) complexes supported by tetraphosphine ligands, meso- and rac-bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso- and rac-dpmppm) were synthesized and characterized to show that the tetranuclear Au(I) alignment varies depending on syn- and anti-arrangements of the two dpmppm ligands with respect to the metal chain. The structures of syn-[Au4 (meso-dpmppm)2X]X'3 (X = Cl; X' = Cl (4 a), PF6 (4 b), BF4 (4 c)) and syn-[Au4 (meso-dpmppm)2]X4 (X = PF6 (4 d), BF4 (4 e), TfO (4 f); TfO = triflate) involved a bent tetragold(I) core with a counter anion X incorporated into the bent pocket. Complexes anti-[Au4 (meso-dpmppm)2]X4 (X = PF6 (5 d), BF4 (5 e), TfO (5 f)) contain a linearly ordered Au4 string and complexes syn-[Au4 (rac-dpmppm)2X2]X'2 (X = Cl, X' = Cl (6 a), PF6 (6 b), BF4 (6 c)) and syn-[Au4 (rac-dpmppm)2]X4 (X = PF6 (6 d), BF4 (6 e), TfO (6 f)) consist of a zigzag tetragold(I) chain supported by the two syn-arranged rac-dpmppm ligands. Complexes 4 d-f, 5 d-f, and 6 d-f with non-coordinative large anions are strongly luminescent in the solid state (λmax = 475-515 nm, Φ = 0.67-0.85) and in acetonitrile (λmax = 491-520 nm, Φ = 0.33-0.97); the emission was assigned to phosphorescence from (3) [dσ*σ*σ* pσσσ] excited state of the Au4 centers on the basis of DFT calculations as well as the long lifetime (a few μs). The emission energy is predominantly determined by the HOMO and LUMO characters of the Au4 centers, which depend on the bent (4), linear (5), and zigzag (6) alignments. The strong emissions in acetonitrile were quenched by chloride anions through simultaneous dynamic and static quenching processes, in which static binding of chloride ions to the Au4 excited species should be the most effective. The present study demonstrates that the structures of linear tetranuclear gold(I) chains can be modified by utilizing the stereoisomeric tetraphosphines, meso- and rac-dpmppm, which may lead to fine tuning of the strongly luminescent properties intrinsic to the Au(I) 4 cluster centers.

Di‐ and Trinuclear Gold Complexes of Diphenylphosphinoethyl‐Functionalised Imidazolium Salts and their N‐Heterocyclic Carbenes: Synthesis and Photophysical Properties

“…[33] Furthermore, both gold atoms feature an approximately linear coordination mode (C1-Au1-Cl1 177.4(3) and P1-Au2-Cl2 174.33 (8)), which is commonly ob- 10 dispersion interaction is not present based on their large distance (d(Au1ÀAu2) = 6.8181(2) ). A closer look at the extended solid-state structure reveals a weak goldgold interaction, which is commonly termed as unsupported aurophilicity (Figure 2).…”

Chiral Self‐Recognition between Stereogenic Tetrapalladium Units Affording Pd8 Chains Supported by Homochiral Tetraphosphines

“…To increase the number of metal atoms, we have developed a linear tetraphosphine, meso ‐bis[(diphenylphosphino‐methyl)phenylphosphino]methane ( meso ‐dpmppm; Scheme a, left), and it was recently disclosed that tetrapalladium units supported by two meso ‐dpmppm ligands, {Pd 4 (μ‐ meso ‐dpmppm) 2 } 2+ , are thermodynamically self‐aligned into a linear octapalladium array of {Pd 8 (μ‐ meso ‐dpmppm) 4 } 4+ in the solution state, which was isolated as discrete molecules of [Pd 8 (μ‐ meso ‐dpmppm) 4 ](BF 4 ) 4 ( 1 ) and [Pd 8 (μ‐ meso ‐dpmppm) 4 L 2 ](BF 4 ) 4 (L=XylNC ( 2 ), CH 3 CN ( 3 ), dmf ( 4 ); Scheme b) . In the present study, we have utilized rac ‐dpmppm (Scheme a, right), which is a stereoisomer of meso ‐dpmppm ( RS ) and consists of an equimolar mixture of ( RR ) and ( SS ) enantiomers with respect to the chiral centers at the inner two phosphine units, and synthesized linear octapalladium chains supported by homochiral tetraphosphines, [Pd 8 (μ‐ rac ‐dpmppm) 4 L 2 ](BF 4 ) 4 (L=CH 3 CN ( 6 ), dmf ( 7 ), XylNC ( 8 )), [Pd 8 (μ‐ rac ‐dpmppm) 4 ](BF 4 ) 4 ( 9 ), and [Pd 8 (μ‐ rac ‐dpmppm) 4 (Cl) 2 ](BF 4 ) 2 ( 10 ). Furthermore, variable‐temperature NMR studies for a 1:1 mixture of 7 (with rac ‐dpmppm) and 4 (with meso ‐dpmppm) revealed unprecedented chiral self‐recognition between the Pd 4 units of {Pd 4 (μ‐ rac ‐dpmppm) 2 } 2+ and {Pd 4 (μ‐ meso ‐dpmppm) 2 } 2+ to restore the Pd 8 chains with homochiral ligands at lower temperature.…”

Double‐Strand DNA Breaks Induced by Paracyclophane Gold(I) Complexes

“…The structure shows that both benzene rings of the paracyclophane backbone are in nearly coplanar arrangement. The Au1−Cl1 and Au1−P1 bond lengths (2.313(3) Å and 2.232(3) Å) are in the expected region . The gold atom shows a linear coordination sphere with a P1‐Au1‐Cl1 bonding angle of 173.7° that only slightly differs from the ideal 180° typically observed for gold(I) compounds.…”