No abstract

No abstract

The metalation of toluene (PhCH3) with a 1: 1 mixtureof n-BuLi/MOtBu (M = K, Rb) at ambient temperature affords orange-red powders of benzylpotassium or benzylrubidium. On addition of N,N,N',N",N"-pentamethyldiethylenetriamine (PMDTA) the precipitates dissolve to give burgundy-red solutions, from which needles of [PhCH2K-PMDTA.O.5PhCH3ln (1) or [PhCH2RbPMDTA], (2) areobtained. X-ray analysis reveals that 1 incorporates half a molecule of toluene per asymmetric unit. In both 1 and 2, the 73 and 76 interaction of one M+ cation with two benzyl fragments gives rise to the formation of polymeric chains. The coordination sphere of the cations is completed by one chelating triamine ligand. M O calculations predict multihapto metal carbon interactions to become more important from Li to Cs and substantiate the solid-state results. Ab initio calculations on three different polymers suggest that the array present in the crystal structure is the most stable. The gated decoupled 13C NMR spectrum of 1 in THF-dg solution reveals a IJ(I3C,lH) coupling constant for the benzylic carbon atom which may be interpreted in terms of a mainly planar configuration of the CH2-group in solution.

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 x Li)2-[[(mu3-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 x [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 [mu4-O)Zn4[(2-C5H4N)-NBz]6] (10b), and [tBu(mu3-O)-Li3(mu6-O)Zn3[(2-C5H4N)NMe]6] (11), respectively, with concomitant oxo-insertion into a Li-C interaction resulting in capping of the fac-isomeric (mu6-O)M3M'3 distorted octahedral core of the latter complex by a tert-butoxide group.

No abstract