Examining metal-phosphorus bonds: Submillimeter spectroscopy of the CrP radical (X⁴Σ⁻)

The submillimeter spectrum of the CrP radical (X⁴Σ⁻) has been recorded using direct absorption techniques in the frequency range 347–545 GHz. This study is the first pure rotational measurement of a metal-phosphide species. CrP was synthesized in an AC discharge in argon by the reaction of gas-phase chromium with phosphorus vapor, produced by a novel source. Twelve rotational transitions of CrP were measured, each consisting of four fine structure components. The spectra were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation constants determined. The 3d phosphides appear to resemble the corresponding nitrides in terms of bonding.