The reaction of solid [RuClCp(PPh 3) 2] with TeSe 3 2- or Se n 2- in DMF leads to the formation of [RuCp(PPh 3)(μ 2-Se 2)] 2 (1). In the structure of this compound the two bridging Se 2 groups lead to a six-membered Ru 2Se 4 ring in a chair conformation. Attached to each Ru center is a PPh 3 ligand in an equatorial position and a Cp ring in an axial position. The compound is diamagnetic. The compound [Ru 2Cp 2(μ 3-Se 2)(μ 3-Se)] 2 (2) is obtained under similar conditions in the presence of air. This structure comprises a centrosymmetric Ru 4Se 6 dimer formed from the two bridging Se groups and the two bridging Se 2 groups. Each Ru center is π-bonded to a Cp ring. The reaction of solid [RuClCp(PPh 3) 2] with a Te n 2- polytelluride solution in DMF leads to the diamagnetic compound [(RuCp-(PPh 3)) 2(μ 2-(1,4-η:3,6- η)Te 6)] (3). Here the Ru centers are bound to a bridging Te 6 chain at the 1, 4, 3, and 6 positions, leading to a bicyclic Ru 2Te 6 ring. Each Ru atom is bound to a Cp ring and a PPh 3 group. This dimer possesses a center of symmetry. The structure of 3 is the first example of a bicyclic complex where fusion occurs along a Te-Te bond. If the same reaction is carried out in DMF/CH 2Cl 2, rather than DMF, then [(RuCp(PPh 3)) 2-(μ2- (1,4-η:3,6-η)Te 6)]·CH 2Cl 2 (4) is obtained. In the solid state it possesses the same Ru 2Te 6 structural unit as does 3, but the unit lacks a crystallographically imposed center of symmetry. The electronic structures of 3 and 4 have been analyzed with the use of first principles density functional theory. Bond order analysis indicates that the Te-Te bond where fusion occurs has a shared bonding charge of about 2/3 of that found for Te-Te single bonds.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry