Donor-Free Homo- and Heteroleptic Sodium Magnesiate Complexes

1 Donor-Free Homo- and Heteroleptic Sodium Magnesiate Complexes 

The homoleptic sodium magnesiate 27 (Fig. 20) represents the first example of a structurally characterized solvent-free tris-alkyl version reported in the frterature. Complex 27 exists as a polymeric ate— prepared by a co-complexation approach by mixing the monometaUic alkyls [NaCH2SiMe3] and [Mg(CH2SiMe3)] in an -hexane/toluene solvent 

The bis(amido) alkyl sodium magnesiate [NaMg(HMDS)2( Bu)]oo 28 (Fig. 20C) is also polymeric however, it adopts a one-dimensional chainlike infinite polymer through an almost linear Na—C( Bu)-Mg bridge. Two 

Interestingly, around the same time that the stmcture of [NaMg (HMDS)2( Bu)] 27 was reported. Hill and co-workers studied the 

The mixed sodium magnesium compounds [Na2(HMDS)2Mg( u)2 (donor)]oo (donor is TMEDA and (R,J .)-TMCDA for 33 and 34, respectively, Fig. 24) are isostructural and can be considered as the first examples of inverse sodium magnesium ate complexes. They can be rationally prepared by combining HMDS(H) with a mixture of BuNa and Bu2Mg in the presence of the corresponding donor molecule in a 2 2 1 1 molar ratio. Normally, ate complexes are associated with bimetallic systems, whereby one of the metals has higher Lewis acidity (ie. Mg ) than the other (ie, Na ), thus the former metal captures more Lewis basic anionic Hgands. 

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