BaAu₂P₄: Layered Zintl Polyphosphide with Infinite _∞¹(<i>P</i>^–) Chains

Abstract

Barium gold polyphosphide BaAu2P4 was synthesized from elements and structurally characterized by single crystal X-ray diffraction. BaAu2P4 crystallizes in a new structure type, in the orthorhombic space group Fddd (No. 70) with a = 6.517(1) Å, b = 8.867(2) Å, c = 21.844(5) Å. The crystal structure of BaAu2P4 consists of Au–P layers separated by layers of Ba atoms. Each Au–P layer is composed of infinite ∞(1)(P–) chains of unique topology linked together by almost linearly coordinated Au atoms. According to Zintl–Klemm formalism, this compound is charge balanced assuming closed shell d10 configuration for Au: Ba2+(Au+)2(P–)4. Magnetic and solid state NMR measurements together with quantum-chemical calculations reveal diamagnetic and semiconducting behavior for the investigated polyphosphide, which is as expected for the charged balanced Zintl phase. Electron localization function and crystal orbital Hamilton population analyses reveal strong P–P and Au–P bonding and almost nonbonding Au–Au interactions in BaAu2P4.