1 research outputs found
Aurophilic interactions in polynuclear Au(I) complexes with phosphine ligands containing imidazole rings
Aurophilic interactions in polynuclear Au(I)
complexes with phosphine ligands containing
imidazole rings
Fiorella Bachechiaa*, Alfredo Burinib, Rossana Galassib
aIstituto di Strutturistica Chimica, C.N.R., Area della Ricerca di Roma,
C.P. 10, 00016 Monterotondo St. (Roma), Italy., bDipartimento di Scienze
Chimiche, UniversitĂ di Camerino, 62032 Camerino, Italy. E-mail:
[email protected]
Keywords: gold complexes, aurophilicity, crystal
structures
The tertiary phosphines of the type (Bzim)3-nPhnP, where Bzim
is 1-benzyl-2-imidazolylphosphine and n varies from 0 to 2,
were synthesised as part of a program aimed to the study of
the coordination chemistry of phosphines containing imidazole
rings. The softer character of imidazole, with respect to other
heterocycles, turned out to be useful in the stabilization of
complexes with soft metals as those of Group 11 in low oxidation
states. These ligands can behave as monodentate or as P, N
bidentate forming dinuclear cationic complexes. With Au(I)
they were found to be able to favour the formation of intraand
intermolecular aurophilic interactions. TheAu(I) complexes
assume considerable interest when aurophilic bonds occur
between gold atoms, since their chemical and physical properties
change to particular characteristics with potential applications
in electronic, optical or sensor devices. In particular short
Au•••Au interactions are considered related to optoelectronic
properties as observed in a number of polynuclear gold
compounds. Here the structures of two Au(I) complexes are
reported. The binuclear complex [ÎĽ-(Bzim)Ph2PAu2(C6F5)2]
adopts a folded conformation with parallel, eclipsed C6F5
rings and a corresponding short AucccAu contact of 3.033(2)Ă….
The tetranuclear cluster complex {[μ-N,N’-(Bzim)3PAuCl]2
Au2}2+c AuCl2
- c AuCl4
- consists in a 12-membered macrocycle
with two gold atoms coordinated to two (Bzim)3P
molecules, in bridging mode, through the nitrogen atoms of the
imidazole rings and two gold atoms coordinated to the
phosphorus atoms of the (Bzim)3P ligands. Two chloride atoms
complete the Au bicoordination. Three strong aurophilic interactions,
Au(1)cccAu(4) [2.989(2)Ă…], Au(2)cccAu(3) [3.014(2)Ă…]
andAu(1)cccAu(2) [3.257(3)Ă…], occur.Aweak gold-gold contact,
Au(3)cccAu(4) [3.766(2)Ă…], is also present.
Understanding molecular interactions
23r