Electronic communication through a poly-yne carbonyldicobalt complex containing an open linear triosmium cluster†
Abstract
The oxidative coupling of 2-[Co2(CO)4(μ-X){μ2-η2-(SiMe3C2)}]-5-(CCH)C4H2S (X = dppa (1), dppm (2)) and 3-[Co2(CO)4(μ-dmpm){μ2-η2-(SiMe3C2)}]-4-(C
CH)C4H2S (3) using standard Eglinton-Glaser conditions yielded 2,2′-[Co2(CO)4(μ-X){μ2-η2-(SiMe3C2)}C4H2S]2-5,5′-(C
C)2 (X = dppa (4), dppm (5)) and 3,3′-[Co2(CO)4(μ-dmpm){μ2-η2-(SiMe3C2)}C4H2S]2-4,4′-(C
C)2 (6), respectively (dppa = (Ph2P)2NH; dmpm = (Me2P)2CH2; dppm = (Ph2P)2CH2). The reaction of 5 with [Os3(CO)11(CH3CN)] afforded 2,2′-[Co2(CO)4(μ-dppm){μ2-η2-(SiMe3C2)}C4H2S]2-5,5′-[Os3(CO)11(μ3-η4-(C
C)2] (7), where the triosmium cluster is open and coordinated as a linear chain to both triple bonds. The electrochemical study of 7 shows that the “Os3” unit significantly enhances the electronic communication between the “Co2” redox centres as compared with 5. Complex 6 was characterized by