THE TRICHLOROGERMANITE(II) ANION AND ITS GOLD(I) COMPLEXES

Tetraphenylphosphonium trichlorogermanite(II) (1) has been prepared (a s a reference compound) from Ph4P+ Cl- and GeCl2(dioxane) in tetrahydr onaphthalene. Its structure has been determined by single crystal X-ra y methods. The lattice contains independent monomeric GeCl3- anions (G e-Cl distances between 2.290 and 2.320 Angstrom, Cl-Ge-Cl angles betwe en 95.33 and 98.27 degrees). Treatment of (Ph3As)AuCl with GeCl2(dioxa ne) affords (Ph3As)AuGeCl3 in high yields as a germylene insertion pro duct (2). The complex is a dimer in the crystal with a short Au--Au co ntact of 2.9415(4) Angstrom and bent As-Au-Ge axes [169.353(13)degrees ]. The GeCl3 ligand has shorter Ge-Cl bonds [2.175 to 2.183 Angstrom] and wider Cl-Ge-Cl angles than in the free anion [100.9 to 101.9 degre es]. The analogous reaction with CH2(AsPh2AuCl)(2) leads only to a mon o-insertion product in the form of a salt with {[CH2(AsPh2)(2)Au]}(2)( 2+) dications and two [ClAuGeCl3](-) anions (3). In the lattice these three ions form a centrosymmetrical tetranuclear unit through short Au --Au contacts. The resulting z-shaped Au--Au--Au--Au chain has distanc es of 3.0499(6) (twice) and 3.1613(8) Angstrom and angles of 118.833(8 )degrees (twice). The geometry of the GeCl3 units is similar to that i n 2. {(Et3N)Au[P(o-Tol)(3)]}(+) PF6- (4) was obtained as a by-product in several reactions with the bulky phosphine and where NEt3 was used as a base. The crystals contain two crystallographically independent c ations with a similar core structure, but different conformations of t he substituents. Both the P-Au and the N-Au bonds are elongated owing to steric effects.