Unusual Reactivity of a Cr₂P₂ Tetrahedral Complex toward Superhydride; Formation of [{CpCr(CO)₂}₂(μ-PH₂)_x(μ-H)_2-x] (x = 1 and 2) and [〈{CpCr(CO)₂}₂(μ-PH)〉{(CpCr)₂(μ,η¹:η¹:η⁵:η⁵-P₅)}]

Abstract

Reaction of [{CpCr(CO)2}2(μ,η2-P2)] (1) with LiBEt3H in THF at −78 °C affords the new phosphanido complexes [{CpCr(CO)2}2(μ-PH2)(μ-H)] (2), [{CpCr(CO)2}2(μ-PH2)2] (3), and [〈{CpCr(CO)2}2(μ-PH)〉{(CpCr)2(μ,η1:η1:η5:η5-P5)}] (4), which have been characterized by single-crystal X-ray diffraction methods. The structure of 4 reveals a triple-decker sandwich complex with a distorted cyclo-P5 middle deck. The EPR spectrum of the paramagnetic (S' = 1/2) complex 4 (T = 130 K) is interpreted with a rhombic-symmetric spin Hamiltonian. A noticeable hyperfine interaction with two 31P nuclei is observed.