Synthesis and characterization of alkali metal iminophosphoranomethanide complexes

Abstract

Herein we report the synthesis of three sets of alkali metal complexes with the iminophosphoranomethanide ligands {CH(SiMe3)P(Ph)2NSiMe3}− (TMSNPC-H) and {CH(SiMe2tBu)P(Ph)2NSiMe3}− (TBDMSNPC-H), the latter of which is first reported here. The compounds of general formula [M(RNPC-H)] (3-M and 4-M; M = Li, Na, K) were obtained via a protonolysis reaction between an alkyl reagent (n-butyllithium, benzylsodium, or benzylpotassium) and the proligand. All resulting compounds were characterized by multinuclear NMR, IR spectroscopy, elemental analysis and single crystal X-ray diffraction. We also attempted to prepare the separated ion pairs of [M(TMSNPC-H)] with the matched crown ethers, and obtained the ‘ate’ complexes [Li(12-crown-4)2]+[Li(TMSNPC-H)2]− (5-Li) and [Na(15-crown-5)2]+[Na(TMSNPC-H)2]− (5-Na), the coordination polymer [{K(18-crown-6)2}{K(TMSNPC-H)(18-crown-6)}(TMSNPC-H)]∞ (6) and separate ion pair complex [K(15-crown-5)2]+[TMSNPC-H]− (7). 5-Li is an unusual lithium-lithiate crown ether species, whilst 5-Na represents the first example of a sodium-sodiate crown-ether complex.