Molybdänkomplexe mit hochalkylierten Cyclopentadienyl‐Liganden

Molybdenum Complexes with Highly Alkylated Cyclopentadienyl Ligands Reaction of hexacarbonylmolybdenum with 1,2,3,4‐tetraisopropylcyclopentadiene gives [(η 5 ‐C 5 i Pr 4 H)Mo(CO) 3 H] ( 1 ), which on treatment with 2,5‐norbornadiene is dehydrogenated to [{(η 5 ‐C 5 i Pr 4 H)Mo(CO) 2 } 2 ](Mo Mo) ( 2 ). The mixed‐substituted dimolybdenum complex [(η 5 ‐C 5 Me 5 )(CO) 2 Mo Mo(CO) 2 (η 5 ‐C 5 i Pr 4 H)] ( 6 ) is accessible, e.g., from [(η 5 ‐C 5 Me 5 )Mo(CO) 3 Cl] and [(η 5 ‐C 5 i Pr 4 H)Mo(CO) 3 ]Na ( 3 ). Complex 3 yields [(η 5 ‐C 5 i Pr 4 H)Mo(CO) 3 Cl] ( 4 ) with CuCl 2 and [(η 5 ‐C 5 i Pr 4 H)Mo(CO) 3 ‐SiHMe 2 ] ( 5 ) with Me 2 HSiCl. Low‐temperature 1 H‐NMR spectra of [(η 5 ‐C 5 i Pr 5 )Mo(CO) 3 CH 3 ] ( 7 ), synthesized from [(η 5 ‐C 5 i Pr 5 )Mo(CO) 3 ]Na and MeI, show the signals of two isomers with different orientation of the isopropyl groups about the five‐membered ring. ΔG ‡ of isopropyl rotation has been calculated to be 55.6 ± 4 kJ/mol. [(η 5 ‐C 5 H 2 t Bu 3 ‐1,2,4)Mo(CO) 3 ]Na reacts with MeI to form [(η 5 ‐C 5 H 2 t Bu 3 ‐1,2,4)Mo(CO) 3 CH 3 ] ( 8 ).