Abstract
Reactions of the chiral racemic carbonyl complex [(η^5^‐C~5~Me~5~)Re(NO)(NCCH~3~)(CO)]^+^·BF~4~^−^ and diphosphanes Ph~2~P(CH~2~)~n~PPh~2~ [2.4:1.0 mol ratio; n = 10 (a), 14 (b)] give the (bridging phosphane)dirhenium complexes [(η^5^‐C~5~Me~5~)Re(NO)(CO){μ‐[PPh~2~(CH~2~)~n~Ph~2~P]‐P,P}(OC)(ON)Re(η^5^C~5~Me~5~)]^2+^·2BF~4~^−^ (73−80%), which are reduced (LiAlH~4~) to the dimethyl complexes [(η^5^‐C~5~Me~5~)Re(NO)(CH~3~){μ‐[PPh~2~(CH~2~)~n~Ph~2~P]‐P,P}(ON)(H~3~C)Re(η^5^‐C~5~Me~5~)] (92−96%). Reactions with HBF~4~·OEt~2~/C~6~H~5~Cl, HC≡CC≡CSiMe~3~, and t__BuOK give, via π‐HC≡C adducts (89−94%), the bis(trimethylsilylbutadiynyl) complexes [(η^5^‐C~5~Me~5~)Re(NO)(C≡CC≡ CSiMe~3~){μ‐[PPh~2~(CH~2~)~n~Ph~2~P]‐P,P}(Me~3~SiC≡CC≡C)(ON)Re(η^5^‐C~5~Me~5~)] (9a,b; 95−66%). Desilylation (wet n__Bu~4~NF) yields labile bis(butadiynyl) complexes, which are coupled [Cu(OAc)~2~/pyridine] to the μ‐octatetraynediyl complexes [(η^5^‐C~5~Me~5~)Re(NO){μ‐[PPh~2~(CH~2~)~n~Ph~2~P]‐P,P}{μ‐(C^1^≡CC≡CC≡CC≡C^8^)‐C^1^,C^8^}(ON)Re(η^5^‐C~5~Me~5~)] (3a,b; 10−23% from 9a,b). These represent some of the few cases of intramolecular oxidative homocouplings of terminal alkynes in metal coordination spheres. The electrochemical properties of 3a,b, which undergo two one‐electron oxidations, are compared to nonmacrocyclic analogs that lack the diphosphane bridge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)