Distortional Effects of Noncovalent Interactions in the Crystal Lattice of a Cp*Ir(III)
Acylhydroxamic Acid Complex: A Joint Experimental–Computational
Study
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Abstract
[Cp*Ir(μ-OH)<sub>3</sub>IrCp*]OH
reacts with PhCONHOH to
give [Cp*Ir(η<sup>2</sup>-ONCOPh)], in which the doubly deprotonated
−NHOH unit binds side-on via N and O, an otherwise unrecorded
binding mode. The X-ray structure shows pyramidalization at Ir together
with secondary bonding between the carbonyl oxygen and Ir (<i>d</i><sub>Ir···O</sub> = 2.873(8) Å). The
related <i>o</i>-hydroxyphenylhydroxamic acid gives
a conventional chelate structure in which both sp<sup>3</sup> O atoms
are bound in deprotonated form. In contrast, PhSO<sub>2</sub>NHOH
reacts with S–N cleavage to give the nitrosyl, [Cp*Ir(NO)(SO<sub>2</sub>Ph)]. A detailed computational analysis identifies noncovalent
interactions in the crystal lattice (crystal-packing effects) as responsible
for the distortion in [Cp*Ir(η<sup>2</sup>-ONCOPh)]