1:1 and 2:1 Lithium Zincates with Intramolecular Coordination. Structures of Li(thf)Zn(C6H4CH2NMe2-2)3 and Li2Zn(C6H4CH2NMe2-2)4

Homoleptic lithium zincates with intramolecular Li−N coordination, i.e., Li(thf) n Zn(C 6 H 4 CH 2 NMe 2 -2) 3 ( n = 0 ( 1 ); n = 1 ( 1(thf) )) and Li 2 Zn(C 6 H 4 CH 2 NMe 2 -2) 4 ( 2 ) have been prepared by reacting [Li(C 6 H 4 CH 2 NMe 2 -2)] 4 with Zn(C 6 H 4 CH 2 NMe 2 -2) 2 . In the solid state 1(thf) is a monomer containing a distorted tetrahedral zinc atom. The zinc is surrounded by three monoanionic C 6 H 4 CH 2 NMe 2 -2 (dmba) ligands, which all show a different bonding mode: η 1 -C bonding to zinc and nitrogen coordination to lithium; η 1,μ 2 -C bridge bonding to zinc and lithium with Li−N coordination; and C,N -chelate bonded to zinc. One thf coordinates to lithium. In the solid state, 2 is a monomeric dilithium tetraarylzincate complex containing a tetrahedral zinc atom. The four dmba ligands are all similarly η 1,μ 2 -C bridge-bonded to zinc and lithium, and each lithium is four-coordinate by two additional Li−N bonds. The reaction of LiCH 2 SiMe 3 and Zn(C 6 H 4 CH 2 NMe 2 -2) 2 did not give a mixed zincate complex but the respective homoleptic zincate complexes instead. Both homoleptic and in situ prepared mixed zincate complexes react readily with 2-cyclohexen-1-one, but the product composition shows that the in situ prepared zincate disproportionates into the corresponding homoleptic zincates prior to reaction.