2- Methyl-5-isopropyl-l,3-cyclohexadiene

The formulas of 37-39 show the substitution of three carbonyls by a conjugated diene. Due to the fact that dienes are four-electron donors, the complexes are electron-deficient species. The electron deficiency is reduced by formation of C—H—Cr three-center, two-electron bonds, previously found for a number of other complexes (43). When 2-methyl-5-isopropyl-l,3-cyclohexadiene is used as a potential ligand, the expected complexes 37r and 39r are not obtained, but instead complexes with the isomeric l-methyl-4-isopropyl-l,3-cyclohexadiene group (37r and 39r ) are formed [Eq. (19)]. Similarly, lk and 11 form not only the corresponding complexes 39k and 391, but also the isomeric complexes with (Z)-l,3-hexadiene (39k ) and with (Z)-2-methyl-1,3-pentadiene (391 ). 

SYNS a-FELLANDRENE FEMA No. 2856 4-ISOPROPYL-l-METHYL-l,5-CYCLOHEXADIENE 5-ISOPROPYL-2-METHYL-l,3-CYCLOHEXADIENE 2-METHYL-5-ISOPROPYL-l,3-CYCLOHEXADIENE a-PHELLANDRENE (FCC)... 

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