Oxygen Capture by Lithiated Organozinc Reagents Containing Aromatic 2-Pyridylamide Ligands

• Published in: Chemistry : a European journal Vol. 7; no. 17; pp. 3696 - 3704
• Main Authors: Davies, Robert P., Linton, David J., Schooler, Paul, Snaith, Ronald, Wheatley, Andrew E. H.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 03.09.2001; WILEY‐VCH Verlag GmbH
• Subjects: lithium; oxygen capture; solid-state structures; zinc
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/1521-3765(20010903)7:17<3696::AID-CHEM3696>3.0.CO;2-O

The sequential reaction of ZnMe2 with a 2‐pyridylamine (HN(2‐C5H4N)R, R=Ph: 1; 3,5‐Xy (=3,5‐xylyl): 2; 2,6‐Xy: 3; Bz (=benzyl): 4; Me: 5), tBuLi and thereafter with oxygen affords various lithium zincate species, the solid‐state structures of which reveal a diversity of oxo‐capture modes. Amine 1 reacts to give both dimeric THF⋅[Li(Me)OZn{N(2‐C5H4N)Ph}2] (6), wherein oxygen has inserted into the Zn−C bond of a {MeZn[N(2‐C5H4N)Ph]2}− ion, and the trigonal Li2Zn complex, bis(OtBu)‐capped (THF⋅Li)2[{(μ3‐O)tBu}2Zn{N(2‐C5H4N)Ph}2] (7). The structural analogue of 6 (8) results from the employment of 2, while the use of more sterically congested 3 yields a pseudo‐cubane dimer [{THF⋅[Li(tBu)OZn(OtBu)Me]}2] (9) notable for the retention of labile Zn−C(Me). Amines 4 and 5 afford the oxo‐encapsulation products [(μ4‐O)Zn4{(2‐C5H4N)NBz}6] (10 b), and [tBu(μ3‐O)Li3(μ6‐O)Zn3{(2‐C5H4N)NMe}6] (11), respectively, with concomitant oxo‐insertion into a Li−C interaction resulting in capping of the fac‐isomeric (μ6‐O)M3M′3 distorted octahedral core of the latter complex by a tert‐butoxide group. The sequential reaction of 2‐pyridylamines (HN(2‐C5H4N)R, R=Ph, 3,5‐Xy (=3,5‐xylyl), 2,6‐Xy, Bz (=benzyl), Me) with ZnMe2, tBuLi and oxygen has afforded new lithium zincates, the solid‐state structures of which reveal a diversity of oxygen‐capture modes. One such product type, [{thf⋅Li(Me)OZn[N(2‐C5H4N)R]2}2] (R=Ph, 3,5‐Xy), is depicted.