(Dicarbonyl)(π-cyclohexadienyl)iron iodide, trichlorostannate, and tris(cymantrenecarboxylato)stannate: Synthesis and molecular structures

A reaction of [(η5-C6H7)Fe(CO)3]BF4 with KI in acetone gave brown crystals of the complex [(η5-C6H7)Fe(CO)2]I (I), which was treated with SnCl2 in THF to form orange crystals of the complex [(η5-C6H7)Fe(CO)2]SnCl3 (II). A reaction of complex II with potassium cymantrenecarboxylate ((CO)3MnC5H4COOK, or CymCOOK) in THF yielded yellow crystals of the complex [(η5-C6H7)Fe(CO)2]Sn(CymCOO)3 (III). Structures I–III were identified using X-ray diffraction. The fragment (η5-C6H7)Fe(CO)2 in complexes I–III remains virtually unchanged. The Fe-I bonds in complex I (2.6407(3) Å) and the Fe-Sn bonds in complexes II and III (2.4854(3) and 2.4787(4) Å, respectively) are appreciably shorter than the sum of the covalent radii of the corresponding elements, probably because of an additional dative interaction of the d electrons of iron with the vacant d orbitals of iodine or tin.