(−)-2-Menthylindenyl and (−)-2-Menthyl-4,7-dimethylindenyl Complexes of Rhodium, Iridium, Cobalt, and Molybdenum

Abstract

Optically active complexes of Rh, Ir, Co, and Mo containing the chiral, menthyl-substituted indenyl ligands (−)-2-menthylindene and (−)-2-menthyl-4,7-dimethylindene are described. Metathetic reaction of the chiral lithium salts of these indenyl systems (1, 2) with the appropriate starting materials of Rh and Ir yielded the complexes (−)-(2-menthylindenyl)Rh(COD) (3), (−)-(2-menthyl-4,7-dimethylindenyl)Rh(COD) (4), (−)-(2-menthylindenyl)Rh(C2H4)2 (5), (−)-(2-menthyl-4,7-dimethylindenyl)Rh(C2H4)2 (6), (−)-(2-menthylindenyl)Ir(COD) (7), (−)-(2-menthylindenyl)Ir(C2H4)2 (8), (−)-(2-menthyl-4,7-dimethylindenyl)Ir(C2H4)2 (9), and (−)-(2-menthyl-4,7-dimethylindenyl)Ir(COE)2 (10). Co2(CO)8 and CoCl2(dppe) react with (−)-2-menthylindenyllithium (1) yielding (−)-(2-menthylindenyl)Co(CO)2 (11) and (+)-(2-menthylindenyl)Co(dppe) (12). (−)-Li[(2-menthylindenyl)Mo(CO)3](THF)2 (13), formed by transmetalation of Mo(CO)6, is oxidized by I2, yielding (−)-(2-menthylindenyl)Mo(CO)3I (14), or by allylic chloride, yielding (allyl)(2-menthylindenyl)Mo(CO)2 (15). All compounds were formed stereomerically pure and were obtained after chromatography by dried alumina under nitrogen. The structures of 3, 4, 6, 7, and 14 were determined by single-crystal X-ray diffractometry. Variable temperature 1H NMR spectra of 5, 6, 8, and 9 were recorded to determine the energy barriers for rotation of ethylene along the metal−indenyl and metal−ethylene axes.

103Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

“…For example, Δ is 0.200(7) Å in dicarbonyl( η 5 ‐indenyl)rhodium (VATYUK),23 0.205(5) in dicarbonyl( η 5 ‐4,5,6,7‐tetramethylindenyl)rhodium (KUWPOH),23 but decreases to 0.186 Å in (−)‐dicarbonyl( η 5 ‐2‐menthyl‐4,7‐dimethylindenyl)rhodium (MIFFIQ) 41. The Δ value is 0.161 Å in bis( η 2 ‐ethylene)( η 5 ‐indenyl)rhodium,42 0.168 Å in (−)‐bis( η 2 ‐ethylene)( η 5 ‐2‐menthyl‐4,7‐dimethylindenyl)rhodium (MORCOL)43 and 0.118 Å in [ μ 2 ‐2‐( η 5 ‐cyclopentadienyl)‐2‐( η 5 ‐indenyl)propane]bis[bis( η 2 ‐ethylene)]dirhodium (POZTIH) 44. Finally, Δ is 0.152 Å in ( η 4 ‐cod)( η 5 ‐indenyl)rhodium(HAPPET),5c but decreases to 0.122 Å in ( η 4 ‐cycloocta‐1,5‐dienyl)( η 5 ‐2‐menthyl‐4,7‐dimethylindenyl)rhodium (MORCIF)43 and to 0.116 Å in (−)‐( η 4 ‐cycloocta‐1,5‐dienyl)( η 5 ‐2‐menthylindenyl)rhodium (MORCEB) 43.…”

“…RhÀC2ÀO2 a [f] 1.866(5) 1.857 ( [f] From X-ray structure of dicarbonyl(h 5 -4,5,6,7-tetramethylindenyl)rhodium (KUWPOH); [23] [g] From X-ray structure of (À)-dicarbonyl(h 5 -2-menthyl-4,7-dimethylindenyl)rhodium (MIFFIQ); [41] [h] From X-ray structure of (h 5 -CpCMe 2 C 9 H 7 )Rh(C 2 H 4 ) 2 ; [44] [i] From X-ray structure of (À)-bis(h 2 -ethylene)(h 5 -2-menthyl-4,7dimethylindenyl)rhodium (MORCOL). [43] the metal environment is very different in as-indacenide and as-indacenediide derivatives. For example, in the case of 10 and 14, two distinct orientations of the ancillary ligand cod are mainly controlled by the electronic structure of the spacer.…”

“…[44] Finally, D is 0.152 ä in (h 4cod)(h 5 -indenyl)rhodium(HAPPET), [5c] but decreases to 0.122 ä in (h 4 -cycloocta-1,5-dienyl)(h 5 -2-menthyl-4,7-dimethylindenyl)rhodium (MORCIF) [43] and to 0.116 ä in (À)-(h 4 -cycloocta-1,5-dienyl)(h 5 -2-menthylindenyl)rhodium (MORCEB). [43] The D values extracted from the cod deriva-tives× backbones and also imposed by us to CO and ethylene cyclopentadienyl indenyl and indacenyl complexes (Table 3) are acceptable distortion parameters falling in the range of those measured in structurally similar ethylene and carbonylated compounds.…”

A chiral menthyl cyclopentadienyl molybdenum tricarbonyl chloro complex: Synthesis, heterogenization on MCM-41/MCM-48 and application in olefin epoxidation catalysis

“…A menthyl moiety attached to the cyclopentadienyl ring of metallocenes is a powerful tool for the amplification of chiral information [36][37][38][39][40][41][42][43][44][45]. Chiral menthyl-derived cyclopentadienyl and indenyl complexes of various transition metals are being widely exploited in different stoichiometric and catalytic asymmetric reactions and with respect to asymmetric structural effects [36][37][38][39][40][41][42][43][44][45].…”

“…Chiral menthyl-derived cyclopentadienyl and indenyl complexes of various transition metals are being widely exploited in different stoichiometric and catalytic asymmetric reactions and with respect to asymmetric structural effects [36][37][38][39][40][41][42][43][44][45]. In the case of molybdenum, the complexes (À)-[(2-menthylindenyl)Mo(CO) 3 I], allyl(2-menthylindenyl)-Mo(CO) 2 and (À)-[(2-menthylindenyl)Mo(CO) 3 ]Li(THF) have been synthesized [38,39]. However, to the best of our knowledge there are no reports on the synthesis of molybdenum complexes with menthylderived cyclopentadienyl ligands and no reports on catalytic applications of molybdenum complexes with menthyl-derived cyclopentadienyl or indenyl ligands.…”