Chemistry (Weinheim an Der Bergstrasse, Germany) | 2021
A Structural Diversity of Molecular Alkaline‐Earth‐Metal Polyphosphides: From Supramolecular Wheel to Zintl Ion
Abstract
Abstract A series of molecular group 2 polyphosphides has been synthesized by using air‐stable [Cp*Fe(η5‐P5)] (Cp*=C5Me5) or white phosphorus as polyphosphorus precursors. Different types of group 2 reagents such as organo‐magnesium, mono‐valent magnesium, and molecular calcium hydride complexes have been investigated to activate these polyphosphorus sources. The organo‐magnesium complex [(DippBDI−Mg(CH3))2] (DippBDI={[2,6‐ i Pr2C6H3NCMe]2CH}−) reacts with [Cp*Fe(η5‐P5)] to give an unprecedented Mg/Fe‐supramolecular wheel. Kinetically controlled activation of [Cp*Fe(η5‐P5)] by different mono‐valent magnesium complexes allowed the isolation of Mg‐coordinated formally mono‐ and di‐reduced products of [Cp*Fe(η5‐P5)]. To obtain the first examples of molecular calcium‐polyphosphides, a molecular calcium hydride complex was used to reduce the aromatic cyclo‐P5 ring of [Cp*Fe(η5‐P5)]. The Ca‐Fe‐polyphosphide is also characterized by quantum chemical calculations and compared with the corresponding Mg complex. Moreover, a calcium coordinated Zintl ion (P7)3− was obtained by molecular calcium hydride mediated P4 reduction.