Characterizing the later 3d cyanides: The submillimeter spectrum of CoCN(X 3Φi)

Abstract

The pure rotational spectrum of the CoCN radical has been recorded in the frequency range 350-500 GHz using direct absorption techniques. This study is the first spectroscopic observation of this molecule by any experimental technique. Spectra of Co (13)CN have been measured as well. These data indicate that this species is linear in its ground electronic state and has the cyanide, as opposed to the isocyanide, geometry. The ground state term has been assigned as (3)Phi(i), based on the measurement of three spin components (Omega=4, 3, and 2) and in analogy to other isovalent cobalt-bearing species. Hyperfine splittings resulting from the (59)Co nuclear spin of I=7/2 were observed in every transition, each of which exhibited an octet pattern. For the lowest energy spin component, Omega=4, vibrational satellite features were also identified arising from the first quantum of the Co-C (v(1)=1) stretch and the v(2)=1 and v(2)=2 quanta of the bending mode, which were split by Renner-Teller interactions. The ground state measurements of CoCN were analyzed with a case a(beta) Hamiltonian, establishing rotational, fine structure, and hyperfine parameters. The vibrational and Co (13)CN spectra for the Omega=4 component were fit as well. An r(0) structure was also calculated, providing estimates of the Co-C and C-N bond distances, based on the Omega=4 transitions. CoCN is the fourth molecule in the 3d transition metal series to exhibit the linear cyanide structure, along with the Zn, Cu, and Ni analogs. The preference for this geometry, as opposed to the isocyanide form, may indicate a greater degree of covalent bonding in these species.

Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

“…However, it should be noted in this point that the flat bending in cyanides may lead to the prediction of somewhat short C-N distances from the experimental data. [55][56][57][58][59][60] Finally, as it can be inferred from Table III, the C-N bond distances in isomers with a cyanide arrangement are slightly shorter than that in cyanogen (1.1705 Å at CCSD(T)/aug-ccpVQZ level). And the opposite is true for the corresponding isomers with an isocyanide arrangement.…”

A theoretical study of FeCN in the 6Δ electronic ground state

“…This r 0 (C-N)-value seemed too short in comparison with C-N bond lengths of comparable molecules, which fall in the range 1.15-1.19 Å , and in comparison with our preliminary value [22] of r e (C-N) = 1.169 Å forX 6 D FeCN, an isomer of FeNC, calculated already at that time at the MR-SDCI + Q + E rel / [Wachters + f (Fe), cc-pVTZ (C, N)] level of theory (see Section 2 below for the notation and the explanation of the acronyms). Too-short, experimentally derived C-N bond lengths have been reported not only forX 6 D FeNC, but also for the triatomic cyanidesX 3 U 4 CoCN (r 0 (C-N) = 1.1313(10) Å [23]), 2 D i,X=5/2 NiCN (r 0 (C-N) = 1.1591 (29) [24] and 1.1590(2) Å [25]), 1 R + CuCN (r 0 (C-N) = 1.1576(1) Å [26]), 2 R + ZnCN (r 0 (C-N) = 1.1464 Å [27]),X 2 P X¼3=2 BrCN + (r 0 = 1.103(78) Å [28]),X 6 R þ CrCN (r 0 = 1.1529(12) Å , r ð1Þ m ¼ 1:148 Å [29]), 1 R + AgCN (r 0 = 1.15527(67) Å , r ð2Þ m ¼ 1:160259ð58Þ Å [30]), and 1 R + AuCN (r 0 = 1.1586(24) Å , r s = 1.158654(10) Å [30]). …”

Computational molecular spectroscopy for NiCN: Large-amplitude bending motion

“…Starting in the 1960s [2][3][4], each subsequent decade has seen proposals of successful methods to describe the large-amplitude bending motion in this context [2][3][4][5][6][7][8][9][10]. Nevertheless, recent experimental studies, for example of FeNC [11] and CoCN [12], report zero-point vibrationally averaged bond length ðr 0 Þ values determined without the effects of the large-amplitude bending motion being accounted for. In a recent paper on FeCN [13], we have listed a number of such experimentally derived bond length values for cyanides and isocyanides that, presumably because of the neglect of large-amplitude bending effects, are suspiciously short.…”