Formation and crystal structures of a monomer–dimer pair of mono(cyclopentadienyl)calcium complexes, [C 5( t-Bu) 3H 2] 2CaI(THF) 2 and {[C 5( t-Bu) 3H 2] 2CaI(THF)} 2

Abstract

The mono(cyclopentadienyl)calcium iodide complex [{(Cp 3T)CaI(THF) x } n ] (Cp 3T=[C 5( t-Bu) 3H 2] −) is generated from the 1:1 reaction of K[Cp 3T] and CaI 2 in THF. No redistribution into [(Cp 3T) 2Ca] and CaI 2(THF) n is observed in THF solution. The mono(ring) compound crystallizes from THF as a monomer with a distorted piano stool geometry; the coordination environment around the calcium consists of a pentahapto [Cp 3T] − ligand, an iodide, and two THF molecules. It is the first structurally authenticated monomeric mono(ring) halide complex of a heavy alkaline-earth metal. From a toluene–THF mixture, the mono(ring) complex crystallizes as an iodide-bridged dimer, with a pentahapto [Cp 3T] − ligand and one terminal THF on each metal atom. The CaI and CaI′ distances are nearly equal at 3.087(2) and 3.101(2) Å.