3a,6a-Diaza-1,4-Diphosphapentalene Complexes with Lewis Acids InI3 and SbCl3

3a,6a-Diaza-1,4-diphosphapentalene (DDP) with indium triiodide forms the [In(DDP)I-3] complex (I) with the ratio In : DDP = 1 : 1. The DDP ligand reacts with antimony(III) chloride to form a coordination polymer, the treatment of which with pyridine in the presence of pyridine hydrochloride affords the [PyH](+)[Sb(DDP)Cl-4)](-) complex (II) (CIF files CCDC nos. 1937822 (I) and 1937823 (II)). The metal is coordinated to the phosphorus atom at an angle to the plane of the heteropentalene cycle (101.9(1)degrees and 106.0(1)degrees for In and Sb, respectively). This indicates that the coordination occurs due to electrons of the heteroaromatic pi system.