Electronic Spectroscopy and Electronic Structure of Copper Acetylide, CuCCH

Abstract

The optical spectrum of the linear CuCCH molecule has been investigated for the first time, using resonant two-photon ionization spectroscopy employing ArF (193 nm) or F2 (157 nm) excimer radiation for photoionization. Scans over the range 19 400-25 200 cm(-1) were conducted, leading to the observation of three electronic band systems. These are identified as the [20.2] ã1 ← X̃ (1)Σ(+), the [23.1] à (1)Σ(+) ← X̃ (1)Σ(+), and the [24.7] B̃ (1)Π ← X̃ (1)Σ(+) systems, although only the first two have been rotationally resolved. The ã1 state is tentatively assigned as having (3)Π1 symmetry, becoming optically accessible through spin-orbit interaction with the B̃ (1)Π state. Vibrational assignments have provided the frequency of the Cu-C stretching mode, ν3, in the ground and all three excited states, along with both bending modes, ν4 and ν5, in the à (1)Σ(+) and B̃ (1)Π states, and the Cu-C≡C bending mode, ν5, in the ground state. Comparisons are made to the known electronic states of CuF, CuCl, CuBr, and CuI, and it is argued that like these molecules, the CuCCH molecule is essentially ionic in both the ground and excited states, with the ground state correlating diabatically to Cu(+) (3d(10), (1)S) + CCH(-) (X̃ (1)Σ(+)) and the excited states correlating diabatically to Cu(+) (3d(9)4s(1), (1,3)D) + CCH(-) (X̃ (1)Σ(+)).

Rotational analysis of the $3_0^1 $31 band of the $\tilde A{}^6\Sigma ^ + \leftarrow \tilde X{}^6\Sigma ^ + $Ã6Σ+←X̃6Σ+ system of CrCCH

“…21 Although a large number of main group metal acetylides have been spectroscopically investigated, as summarized in our recent paper on CuCCH, 25 the only transition metal acetylides to have received spectroscopic attention to our knowledge are CrCCH, where vibronic spectra have been recorded and analyzed; 8 CuCCH, where electronic 25 and pure rotational 26 spectra are available; and ZnCCH, for which pure rotational spectra have been measured. 27 In this article we report the rotational analysis of the previously observed 3 1 0 band of thẽ A ←X band system of CrCCH, 8 confirming our conjecture that theà ←X system is a 6 + ← 6 + transition.…”

A large enhancement of (hyper)polarizabilities of polyyne capped by Cu

“…Geometries of the linear CuC 2n H and CuC 2n Cu (n = 1-7) molecules were firstly constructed by hand on the basis of the recent experimental works [20,22,23]. Then all the constructed geometries were optimized by using the ab initio calculation method.…”

“…To the best of our knowledge, there are few reports on the geometrical parameters of the linear CuC 2n H and CuC 2n Cu (n = 1-7) molecules [23] except some reports on their optical spectra such as infra-red [20,21] and resonant two-photon ionization spectroscopy [22]. Sun et al [23] deduced the exact geometrical parameters of the linear CuC 2 H molecule from its experimental rotational spectrum; thus we investigated the basis set and method dependences of bond lengths of the linear CuC 2 H molecule to determine the optimization method for other molecules considered.…”

“…Recently, the Cu and Ag end-capping polyynes, Cu/Ag polyynides and Cu/Ag acetylides, have been successfully synthesized and characterized by the Fourier transform infrared, electronic, and rotational spectra [19][20][21][22][23]. Both Cu and Ag have appealing linear and nonlinear optical properties when they individually exist as nanoparticles or nanoplanets [24][25][26][27].…”

Millimeter-wave spectroscopy of CrC (X3Σ−) and CrCCH (X̃ 6Σ+): Examining the chromium-carbon bond

“…For the metal monoacetylides, CuCCH and ZnCCH have been characterized using pure rotational spectroscopy, 17,18 and recently NiCCH and CuCCH have been studied in the optical regime. 19,20 Besides identifying electronic states, such work suggested that the CCH moiety retains an acetylenic structure when bonded to copper or zinc. VCH and TiCH have also been studied in the optical regime by Merer and collaborators, who found their structures to be linear.…”