Metalation of Aryl-bis(3-alkyl-5-methylpyrazol-1-yl)- methane (Alkyl=Me, Ad; Aryl=Ph, C6H4-2−OH) with NaN(SiMe3)2, KN(SiMe3)2, and Ca{N(SiMe3)2}2

Deprotonation of phenyl-bis(3,5-dimethylpyrazolyl)methane (HC(Ph)(PzMe2)2, 1 a) with [(thf)2Ca{N(SiMe3)2}2] in THF at −40 °C yields heteroleptic [(thf)2Ca{N(SiMe3)2}{C(Ph)(PzMe2)2}] (2 a) and finally homoleptic [(thf)Ca{C(Ph)(PzMe2)2}2] (2 b). However, these complexes degrade at room temperature to calcium bis(pyrazolate) and 2-phenyl-4,6-dimethylpyrimidine (3 a). This degradation is accelerated when bulky phenyl-bis(3-adamantyl-5-methylpyrazolyl)methane (HC(Ph)(PzAd,Me)2, 1 b) is treated similarly and 2-phenyl-4-adamantyl-6-methylpyrimidine (3 b) forms quickly. Sodiation of 1 a and 1 b with NaN(SiMe3)2 yields [{HC(Ph)(PzMe2)2}Na{C(Ph)(PzMe2)2}] (4 a) and [{HC(Ph)(PzAd,Me)2}Na{C(Ph)(PzAd,Me)2}] (4 b). The stronger metalation reagent benzylpotassium is able to quantitatively deprotonate 1 b leading to dinuclear [K{C(Ph)(PzAd,Me)2}]2 (4 c). The metathetical approach and the reaction of 4 c with metal(II) halides of Mg, Ca and Zn again leads to degradation and formation of pyrimidine 3 b. This decomposition of the ligand can be circumvented when the sidearm contains the anionic charge. Thus, 2-hydroxyphenyl-bis(3-adamantyl-5-methylpyrazol-1-yl)methane (1 c) reacts with [(thf)2Ca{N(SiMe3)2}2] in THF to the homoleptic complex [(thf)4Ca{O−C6H4−CH(PzAd,Me)2}] (2 c). In this complex, THF and pyrazolyl bases compete in the coordination sphere and preparation of a heteroleptic complex fails. To avoid the binding competition between THF and pyrazolyl bases and to stabilize heteroleptic calcium complexes, the reaction has been repeated in toluene yielding [Ca{N(SiMe3)2}{O−C6H4−CH(PzAd,Me)2}]2 (2 d). © 2022 The Authors. European Journal of Inorganic Chemistry published by Wiley-VCH GmbH