Synthesis and structures of tris(2-pyridyl)aluminate sandwich compounds [{RAl(2-py')_2}_2M] (py' = 2-pyridyl, M = Ca, Mn, Fe)

摘要

Reactions of the lithium salts [{RAl(2-py')_3Li·THF] [2-py' = 2-py (2-pyridyl), R = ~nBu (1), R = ~(sec)Bu (2); py' = 5-Me-2-py (5-methyl-2-pyridyl), R = Me (3); 6-Me-2-py (6-methyl-2-pyridyl), R = Et (4b)] with the corresponding metal(II) halides give the new heterobimetallic sandwich compounds [{RAl(2-py)_3}_2M] [R = ~nBu, M = Ca (5), Mn (6), Fe (7); R = ~(sec)Bu, M = Ca (8), Mn (9)], [{MeAl(5-Me-2-py)_3}_2Ca] (10) and [{EtAl(6-Me-2-py)_3}_2Ca] (11) and the co-complex [{EtAl(6-Me-2-py)_3}Mn(μ-Cl)Li{(6-Me-2-py)_3AlEt}] (12). While neither the bridgehead group (R) nor remote ring Me-groups have any impact on metal coordination in 5–10, the introduction of Me groups into the pyridyl substituent at the 6-position (i.e., adjacent to the donor pyridyl-N atoms) has a marked effect on the ability of the ligands to form sandwich arrangements, as seen in the distorted structure of the sandwich compound 11 and in the formation of the cocomplex 12, consisting of a two half-sandwich arrangement linked by a μ-Cl ion. The syntheses and solid-state structures of the new precursor 4b and the new compounds 5–12 are reported.