From 3D to 2D: structural, spectroscopic and theoretical investigations of the dimensionality reduction in the [PtAl2]δ- polyanions of the isotypic MPtAl2 series (M=Ca-Ba, Eu) - Stegemann, Frank; Block, Theresa; Klenner, Steffen; Zhang, Yuemei; Fokwa, Boniface P. T.; Timmer, Alexander; Mönig, Harry; Doerenkamp, Carsten; Eckert, Hellmut; Janka, Oliver (Chemistry: a European journal, 2019)