99665-64-2Relevant academic research and scientific papers
Synthesis and structural characterization of binuclear gold(I) complexes derived from two new A-frame ligands
Schmidbaur,Pollok,Herr,Wagner,Bau,Riede,Müller
, p. 566 - 574 (2008/10/08)
The molecular structure of the potential A-frame ligand cyclopropylidenebis(diphenylphosphine), cdpp, has been determined by an X-ray diffraction analysis. The ground-state conformation in the crystal is a rotamer with the lone pairs of electrons at phosphorus in cis and trans (Z or E) positions relative to the cyclopropane plane. This ligand forms 1:2 complexes with AuCl, AuI, and AuCH3. The 1:1 complex with AuCl (7b) has the expected eight-membered ring structure, as determined by an X-ray diffraction study of the trimethanol solvate, but one of the chloro ligands is found to be dissociated from the gold(I) centers. In the remaining dinuclear cation with an Au-Au contact of 2.907 (1) ?, the residual chloro ligand is positioned above one gold atom with an Aul-Au2-Cl1 angle of only 75.4 (1)°. The structural inequivalence of the metal atoms in the solid is confirmed by 197Au M?ssbauer data. Solution NMR data in CDCl3 indicate a virtually symmetrical structure due to exchange processes. A related autodissociation of only one chloro ligand from a dinuclear gold(I) complex was also found in the X-ray analysis of the 1:1 complex of AuCl with 2-methoxyethylidenebis(diphenylphosphine) (3b). In this complex, obtained by methanol addition to the vinylidene precursor as the tetramethanol solvate, the residual chlorine is attached to one gold atom on the projection of the Au-Au axis (Au1-Au2 = 3.002 (1) ?; Au1-C13 = 2.963 (3) ?; Au2-Au1-C13 = 176.2 (1)°). The methoxy groups of the two side chains are oriented toward Au2. These peculiar interactions lead to very uncommon coordination spheres for both gold(I) centers in the cation of 3b. Au M?ssbauer data of the solid and NMR spectra of the solution are again in agreement with an unsymmetrical and symmetrical structure, respectively. Crystal data for cdpp: C2/c, a = 27.064 (6) ?, b = 10.146 (2) ?, c = 17.562 (4) ?, β = 114.30 (2)°, V = 4395.1 ?3, Z = 8, Rw = 0.041 for 262 refined parameters and 2437 reflections with Fo ≥ 4σ(Fo). Crystal data for 7b: P21/c, a = 17.283 (4) ?, b = 17.027 (4) ?, c = 19.284 (4) ?, β = 108.75 (2)°, V = 5373.7 ?3, Z = 4, Rw = 0.044 for 343 parameters and 6045 observed data. Crystal data for 3b: P212121, a = 11.388 (2) ?, b = 22.588 (5) ?, c = 22.737 (5) ?, V = 5840.9 ?3, Rw = 0.042 for 378 parameters and 4549 observed reflections.
