Publisher Summary This chapter discusses the field of transition-metal complexes of isocyanides developed slowly over more than a century to a respectable subarea in coordination chemistry and which, in the process, seems to have attracted very little attention. The valence-bond pictures for an isocyanide and carbon monoxide and for metal complexes of these ligands emphasize the similarities of both the ligands and their complexes. The insertion of a carbonyl group into a metal–alkyl or metal–aryl bond and the reverse reaction involving decarbonylation of an acyl complex have been studied from both the synthetic and mechanistic points of view. The reactions of nucleophilic reagents with cationic and uncharged metal carbonyl complexes have received much attention in the past, and it is not surprising that these studies have now been extended to isocyanide metal complexes. Perhaps the greatest excitement in the field of metal isocyanide complex chemistry has been generated by the observation that a variety of protonic substances (alcohols, thiols, amines, and hydrazine) add to the coordinated isocyanide ligand. A number of chemists have been interested in the chemistry of cobinamine and cobaloxime complexes of several ligands, including isocyanides.

Transition Metal-lsocyanide Complexes

Recent advances in the chemistry of isocyanide complexes

Vibrational spectra and force constants of pure ammine complexes

Skeletal vibrational spectra, force constants, and bond properties of transition metal ammine complexes

Synthetic chemistry enables a bottom-up approach to quantum information science, where atoms can be deterministically positioned in a quantum bit or qubit. Two key requirements to realize quantum technologies are qubit initialization and read-out. By imbuing molecular spins with optical initialization and readout mechanisms, analogous to solid-state defects, molecules could be integrated into existing quantum infrastructure. To mimic the electronic structure of optically addressable defect sites, we designed the spin-triplet, V3+ complex, (C6F5)3trenVCNtBu (1). We measured the static spin properties as well as the spin coherence time of 1 demonstrating coherent control of this spin qubit with a 240 GHz electron paramagnetic resonance spectrometer powered by a free electron laser. We found that 1 exhibited narrow, near-infrared photoluminescence (PL) from a spin-singlet excited state. Using variable magnetic field PL spectroscopy, we resolved emission into each of the ground-state spin sublevels, a crucial component for spin-selective optical initialization and readout. This work demonstrates that trigonally symmetric, heteroleptic V3+ complexes are candidates for optical spin addressability.

Trigonal Bipyramidal V3+Complex as an Optically Addressable Molecular Qubit Candidate

The Raman and low-frequency infrared spectra of the trigonal-bipyramidal complexes Co(RNC)5ClO4(R = Me, Et, Ph) have been recorded and assigned. It is found that δ(CoCN) modes occur at higher frequencies than ν(Co—CN) modes. Although Raman spectra of the blue and yellow forms of Co(PhNC)5(ClO4)2 could not be obtained, the low-frequency infrared spectra are consistent with the C4v structure previously suggested (1). The dimeric complexes Co2(RNC)10(ClO4)4 (R = Me, Et) have been studied, and tentative assignments of the Raman and infrared spectra made on the basis of D4d symmetry. Spectra of the complexes Co2(RNC)10I(ClO4)3 (R = Me, Et) strongly support the previously suggested structural formulation (2) [(MeNC)5Co—I—Co(MeNC)5](ClO4)3, and furthermore indicate that the Co—I—Co skeleton is linear.

Vibrational spectra of some isonitrile complexes of cobalt(I) and (II)

The vibrational spectra of simple cobalt(III) and chromium(III) ammine complexes

The far i.r. and Raman spectra of the compounds [Co(NH3)6][CuCl5], [Cr(NH3)6][CuCl5], and (dienH3)[CuCl5](dien = diethylenetriamine), have been recorded. The spectra of the anions have been assigned on the basis of a D3h environment of the copper(II) ion.

P. M. Boorman

Papers

Vibrational spectra of some isonitrile complexes of cobalt(I) and (II)

The vibrational spectra of simple cobalt(III) and chromium(III) ammine complexes

Far infrared and Raman spectra of the pentachlorocuprate(II) anion