SYNTHETIC AND MOLECULAR-ORBITAL STUDY OF ETA-3(3E)-BUTADIENYL COMPLEXES OF MOLYBDENUM

Complexes of general formula MoCl(CO)2(eta-3-CH2C(CONRR')C = CH2)L2 (L2 = 2,2'-bipyridine, 1,10-phenathroline) that contain an eta-3(3e)-buta-2,3-dienyl ligand are formed by the reaction of Ph4P-[MoCl(CO)3L2] with methanolic 1,4-dichlorobut-2-yne in the presence of primary or secondary amines HNRR' (R = H, R' = Me, Et, Pr(n), Ph, CH2CH = CH2, CH2C = CH; R = R' = Me, Et, Pr(n)). The perfluorocarboxylate complex Mo(CO)2(eta-3-CH2C(CONHMe)C = CH2)(2,2'-bipyridine)(O2CC3F7) (11), formed by anion exchange, crystallizes in a triclinic space group P1BAR with a = 7.440 (3) angstrom, b = 9.727 (3) angstrom, c = 17.748 (6) angstrom, alpha = 100.58 (3)-degrees, beta = 94.84 (2)-degrees, gamma = 103.88 (5)-degrees, V = 1214.6 (7) angstrom 3, and Z = 2; R = 0.064, R(w) = 0.072 for 2296 reflections with I greater-than-or-equal-to 3-sigma-(I) having 2 less-than-or-equal-to theta less-than-or-equal-to 22-degrees. An EHMO study of the bonding and potential reactive centers in the ligated eta-3-butadienyl ligand is also reported.