Chapter TwoCALCIUM, STRONTIUM, GERMANIUM, TIN, AND LEAD BIS(TRIMETHYLSILYL)AMIDO DERIVATIVES AND 2,2,6,6‐TETRAMETHYLPIPERIDIDO AND N‐ISOPROPYLPHENYLAMIDO DERVATIVES OF POTASSIUM AND CALCIUM

1. INTRODUCTION

In this chapter, the synthesis of ─N(SiMe3)2 derivatives of some main group 2 and 14 elements, as well as 2,2,6,6‐tetramethylpiperidido and ─N(Ph)Pri salts of potassium and calcium, is described.

The role that the ─N(SiMe3)2 ligand has played in main group structural chemistry has been the subject of two recent reviews dealing with metals of the s and p blocks.1, 2 A prior report in an earlier volume3 has described the synthesis of the group 1 lithium and sodium bis(trimethylsilyl)amide based on preparations originally reported by Wannagat and coworkers in the early 1960s.35 The lighter group 2 silylamide Be{N(SiMe3)2}26 and various N(SiMe3)2 derivatives of magnesium including Mg{N(SiMe3)2}27 were described in 1965 and 1972, respectively. The heavier Ca, Sr, and Ba analogues were not reported8 until the 1990s, however. Since that time, their chemistry has been developed in interesting directions that include their use in catalysis,9 as metalating agents, and in inverse crown structures.1012

The originally described synthetic route to the heaviest group 2 element amides involved a displacement reaction between the group 2 metal (Mg–Ba) and Sn{N(SiMe3)2}2 (see below), which affords the calcium and strontium derivatives in good (>80%) yields.8 In the crystalline state, the ...

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