Syntheses and properties of NCN-bridged tri-and tetranuclear complexes of cobalt and rhodium

Abstract The reaction of [Cp ∗ CoI 2 ] 2 ( 1b ) with 2 equiv of NaNCNH affords the 16-membered macrocyclic NCNH-bridged tetracobalt(III) complex [Cp ∗ CoI(μ 2 -NCNH- N , N ′)] 4 ( 2b ), while that with 2 equiv of Na 2 NCN yields the C 3 -elongated cubane-like NCN-bridged tetracobalt(III) complex [Cp ∗ Co(μ 3 -NCN- N , N , N ′) 3 (CoCp ∗ ) 3 (μ 3 -NCN- N , N , N )] ( 4b ). Treatment of [Cp ∗ RhCl 2 ] 2 ( 1c ) with 2 equiv of NaNCNH gives the C 3 -elongated cubane-like tetrarhodium(III) complex [Cp ∗ Rh(μ 3 -NCN- N , N , N ′) 3 (RhCp ∗ ) 3 (μ 3 -NCN- N , N , N )] ( 4c ) via the macrocyclic complex [Cp ∗ RhCl(μ 2 -NCNH- N , N ′)] 4 ( 2c ). On the other hand, the reaction of [Cp ∗ CoCl] 2 ( 7 ) with Na 2 NCN affords the anionic bis(NCN)-capped tricobalt(II) complex Na[(Cp ∗ Co) 3 (μ 3 -NCN- N , N , N ) 2 ] ( 6 ). The molecular structures of complexes 2b  · CH 2 Cl 2 and 4c  · 2C 6 H 6 have been confirmed by X-ray analyses. The electrochemical properties of these types of NCN-bridged group 9 metal complexes have also been examined.