Examples of Different Reactions of Benzylsulfanyl‐Substituted Alkynes with Selected Complexes of Ti^II and Co^I

Abstract

Abstract Reactions of the group 4 metallocene alkyne complexes [Cp 2 M(L)(btmsa)] (Cp = η 5 ‐cyclopentadienyl = η 5 ‐C 5 H 5 , btmsa = η 2 ‐Me 3 SiC 2 SiMe 3 ; 1 : M = Ti, L = none; 2 : M = Zr, L = pyridine) and of the [(triphos)Co I ] moiety [triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane] with the benzylsulfanyl‐substituted acetylenes PhCH 2 S–C 2 –SCH 2 Ph ( 3 ) and PhCH 2 S–C 2 –SFmoc ( 4 ) (Fmoc = fluorenylmethoxycarbonyl) have been investigated. Complex 1 reacted with 3 to give a mixture of a violet solid and [Cp 2 Ti(SCH 2 Ph) 2 ] ( 5 ). Subsequently, the violet solid transformed in toluene at 70 °C into the dinuclear complex [(Cp 2 Ti) 2 (μ‐κ 2 ‐κ 2 ‐BnSC 4 SBn)] ( 6 ) displaying two [Cp 2 Ti] moieties bridged by a 1,4‐bis(benzylsulfanyl)‐1,3‐butadiyne in the trans configuration. Complex 6 was further degraded in toluene at 100 °C to the tetranuclear cluster [CpTiS] 4 ( 7 ). Similar reactivity was deduced indirectly for the reaction partners 1 / 4 and 2 / 3 . For Co I , the side‐on alkyne complexes [(triphos)Co( 3 )](PF 6 ) ( 9 ‐PF 6 ) and [(triphos)Co( 4 )](PF 6 ) ( 10 ‐PF 6 ) were obtained. Reductive removal of the benzyl groups in 9 ‐PF 6 and subsequent coordination of the [Cp(PPh 3 )Ru II ] + moiety led to the dinuclear complex [(triphos)Co(μ‐η 2 ‐κ 2 ‐C 2 S 2 )RuCp(PPh 3 )] ( 13 ) displaying acetylene dithiolate (acdt 2– ) in a side‐on carbon–sulfur chelate coordination mode. In contrast, the reaction of 10 ‐PF 6 with piperidine under very mild conditions resulted in the thio‐alkyne complex [(triphos)Co(PhCH 2 SC 2 S)] ( 11 ) bearing a terminal sulfur substituent at the coordinated alkyne. However, a subsequent rearrangement reaction led to the Co III dithiolene complex [(triphos)Co{S 2 C 2 (NC 5 H 10 )(CH 2 Ph)}](PF 6 ) ( 14 ‐PF 6 ). The intricate rearrangement very likely involves a dinuclear Co species with a η 2 ‐κ 2 coordination of the C 2 S 2 moiety.