Two different faces of the triangular cluster Rh3Cp3(μ2-CO)3 towards metalloelectrophiles: Structural and theoretical study.

The tetrahedral clusters [(C 4 Me 4)CoRh 3 Cpʹ 3 (μ 3 -CO) 3 ]+ (2 ; Cpʹ = C 5 H 4 Me) and [(Ph 3 P)AuRh 3 Cpʹ 3 (μ 2 -CO) 3 ]+ (3) were synthesized by reactions of Rh 3 Cpʹ 3 (μ 2 -CO) 3 (1b) with metalloelectrophiles [(C 4 Me 4)Co]+ (generated from [(C 4 Me 4)Co(C 6 H 6)]+ under visible-light irradiation) and [(Ph 3 P)Au]+ (generated from (Ph 3 P)AuCl/Tl+). They were isolated as salts with PF 6 − anion, and the structures of 2 PF 6 and 3 PF 6 were determined by X-ray diffraction. The structural data gave evidence that the coordination of [(C 4 Me 4)Co]+ occurs to the face of 1b with the CO ligands, while the [(Ph 3 P)Au]+ species reacts with the opposite face of 1b. The latter interaction is accompanied by elongation of the Rh–Rh bonds within the rhodium triangle by 0.1 Å. DFT calculations (at the BP86/TZP level) revealed that the selectivity of the metalloelectrophile coordination is determined by orbital control. Image 1 • New heteronuclear tetrahedral CoRh 3 and AuRh 3 clusters were synthesized. • The triangular rhodium cluster showed dual reactivity towards metalloelectrophiles [(C 4 Me 4)Co]+ and [(Ph 3 P)Au]+. • The [(C 4 Me 4)Co]+ and [(Ph 3 P)Au]+ species prefer π- and σ-bonding, respectively. • The selectivity of the metalloelectrophile coordination is determined by orbital control. [ABSTRACT FROM AUTHOR]