(Z)-N-(2-amino-1,2-dicyanovinyl) formimidate is a compound of interest due to its potential applications in thin film technologies, such as sensors or electronic materials [3] [4] . Its molecular structure, featuring cyano (C≡N), formimidate (O-C=N), and amino (−NH₂) groups, makes it suitable for spectroscopic characterization. Raman spectroscopy, which detects vibrational modes sensitive to molecular polarizability, and infrared (IR) spectroscopy, and which targets dipole moment changes, provide complementary insights into the compound’s functional groups. This study characterizes the formimidate sample using Raman spectroscopy, supplemented by IR data from Alves et al. (1990) and US Patent #US 8,518,901 B2 (2013) to confirm molecular identity and explore sample variations.

The samples were prepared as a solid compound according to the modified synthesis protocol by Guei et al. . The compound was synthesized, and the structure was confirmed via ¹H and ¹³C NMR, melting point (mp), IR spectroscopy as detailed in the references [1] [2] [5] and Raman spectroscopy.

Raman and IR Spectroscopy

Raman spectra were acquired using a 100 mW, 785 nm laser source with a 60-second integration time and 2-average scans. In addition, the Raman system used a spectral resolution of 6 cm⁻¹ and a fiber-coupled laser output of 100 microns, with a laser power of 100 mW at a working distance of 7 mm. The spectral coverage of the system ranges from 250 to over 2350 cm⁻¹ capturing the key vibrational modes of the compound. Hence, the results of this work focus on the characteristic Raman bands of the sample observed within these ranges. Additional details of the Raman system used and the experimental setup are discussed elsewhere [12] [13] .

FT-IR spectral data were acquired, and from Alves et al. (1990) and US Patent #US 8,518,901 B2 (2013) , which report absorption bands characteristic of the compound’s functional groups.

Synthesis, NMR, and Melting Point

The Ethyl (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate (Scheme 1) was synthesized according to a modified procedure of Guei et al. , following the original procedure of Alves et al. and the US Patent #US 8,518,901 B2 . It was characterized by melting point and NMR spectroscopy (see methods). Starting with commercially available diaminomaleonitrile and triethylorthoformate, the titled compound was synthesized in a moderate yield (3.5 g, 21 mmol, 70%), with a melting point of 132 - 134˚C (lit.⁽⁷⁾ 132 - 135˚C).

Raman and IR Spectroscopy of Ethyl (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate Data

Raman and IR spectroscopy provide complementary insights due to their sensitivity to different vibrational modes. Raman spectroscopy excels at detecting symmetric stretches, such as the C≡N stretch at 2208 cm⁻¹, while IR is more sensitive to polar modes, like the NH/NH₂ stretches at 3200–3400 cm⁻¹. The combination of these techniques ensures a comprehensive characterization of the compound’s functional groups, confirming its molecular structure. In this study, the Raman bands assignment and the characterization of the compound are primarily based on the acquired data and the literature values [14] [15] .

Raman spectra of Ethyl (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate Data

The peaks at 1223 and 1369 cm⁻¹ are assigned to C-O and N-H consistent with the formimidate group. The higher intensity peaks in the compound suggest a possible crystalline structure. The strong peaks at 1591 and 1634 cm⁻¹ are assigned to the C=N and C=C stretching vibration, consistent with the conjugate system. This assignment aligns with literature values for C=N stretches in conjugated systems, typically observed in the 1475 - 1700 cm⁻¹ range . The peak at 2205 and 2243 cm⁻¹ corresponds to the C≡N stretching vibration, typical for cyano groups in organic nitriles, where the C≡N stretch appears around 2200 - 2300 cm⁻¹ (Smith, 2019 ). This peak’s consistency across both samples supports the presence of cyano groups.

Figure 1(a) shows the Raman measurement of the Ethyl (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate sample observed within the spectral coverage of the system. As shown in the figure, the Raman bands located at 1223, 1369, 1591, 1634, 2206, and 2242 cm⁻¹ are very distinct as compared with the other multiple weak bands. The Raman band assignments of these major bands corresponding to the vibrational modes of the compound’s functional groups are summarized in Table 1 . To enhance the resolution of the weak bands captured, the region from 280 - 1000 cm⁻¹ is separately plotted ( Figure 1(b) ).

As mentioned above, the Raman spectroscopic characterization of the Ethyl (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate primarily focuses on the Raman bands observed within the 250 to 2350 cm⁻¹ region. The result revealed several weak, medium, and prominent bands ( Figure 1(a) and Figure 1(b) ), indicating the vibrational modes of the functional groups. In general, ethyl functional groups symmetric CH₃ deformation vibrations, CH₂ twisting vibrations, and CH₂ rocking vibrational Raman bands are located in the 1360 - 1390 cm⁻¹, 1200 - 1290 cm⁻¹, and 1060 - 1190 cm⁻¹ regions, respectively . Accordingly, the peak observed at 1369 cm⁻¹ is assigned to symmetric CH₃ deformation vibration, which is within the typical region for ethyl functional groups. The Raman peak observed at 1223 cm⁻¹ indicates the CH₂ wagging vibrations in the formimidate sample, which is within the most common spectral region (1215 - 1285 cm⁻¹) for the wagging vibration mode of this functional group.

In addition, the bands within the 880 - 1000 cm⁻¹ region exhibit rocking vibration of the CH₃ functional group in the compound. The results of the Raman measurement show weak Raman peaks located at 880 and 996 cm⁻¹, indicating the presence of this mode of vibration of the functional group in the compound. The weak bands in the region 575 - 730 cm⁻¹ are due to the C-H stretching vibrations. Hence, the weak bands shown in Figure 1 , captured at 593, 634, 666, 698, and 719 cm⁻¹, exhibit the C-H stretching vibrations in the compound. The C-H in-plane deformations are characterized by the bands located at 996 and 1223 cm⁻¹, which are within the 990 - 1290 cm⁻¹ region common to both the in-plane deformation of C-H and C-O bond stretching vibrations.

The C=C stretching vibrations commonly take place in the 1430 - 1625 cm⁻¹ region. Hence, the sharp and strong Raman peak at 1591 cm⁻¹ is assigned to the stretching vibration of this bond in the formimidate compound. The band at 1369 cm⁻¹, which overlaps with the CH deformations, and the weak band at 996 cm⁻¹ are also characteristic stretching vibrations of the double bond. Similarly, the weak Raman peak located at 1170 cm⁻¹ is the characteristic C-N stretching band of amines, and the bands at 2206 and 2242 cm⁻¹ are assigned to C≡N stretching vibration of the bond in the formimidate structure, which is within the common region for this bond (2000 - 2250 cm⁻¹). The weak Raman peak located at 398 cm⁻¹ is assigned to C-C≡N deformation vibration, which commonly exhibit peaks in the 340 - 390 cm⁻¹ region, and the weak bands at 412 and 471 cm⁻¹ are assigned to the in-plane bending of the C-CN bond in the compound, which is generally in the 380 - 430 cm⁻¹ region of the spectrum.

FT-IR (Fourier-Transform Infrared Spectroscopy) Data

The acquired FT-IR spectra on a Nicolet Is10 Fourier-Transform Infrared Spectroscopy (FTIR) showed major peaks at 3416, 3304, 2243, 2208, 1635, 1606 cm⁻¹ which were corroborated by the literature data IR (KBr) at 3309 cm⁻¹ (N-H stretches), 2247 cm⁻¹ (C≡N stretches), 2207 cm⁻¹ (C≡N stretches), and ~1636 cm⁻¹ (C=N stretches), 1608, 1256 cm⁻¹ (C-O stretches), 810 cm⁻¹. These bands confirm the presence of amino, cyano, and formimidate functional groups, complementing the Raman findings. The C≡N stretch, being a symmetric vibration, is strong in Raman but also detectable in IR, while the NH/NH₂ stretches are more prominent in IR due to their polar nature.

Raman spectroscopy was employed in this study to confirm the chemical structure of (Z)-N-(2-amino-1,2-dicyanovinyl) formimidate. The Raman spectra of the formimidate, acquired for the first time in this study, were consistent with the vibrational modes of the functional group associated with the compound as reported in the literature. The acquired FT-IR data, and the literature support these findings, highlighting the presence of key functional groups. The complementary nature of Raman and IR techniques enhances the reliability of the characterization. The assignments of Raman peaks were validated through comparison with literature data and complementary IR spectra [1] [2] [14] . The C=N and C≡N stretches are consistent with expected frequencies for conjugated systems and nitriles, respectively [14] [15] . Future work could involve computational modeling, such as density functional theory (DFT), to refine peak assignments and explore the effects of structural variations on spectral features.

The authors gratefully acknowledge the support of Alabama A&M University for providing laboratory facilities and resources essential for this research. Special thanks are extended to the Department of Mechanical & Civil Engineering and Construction Management, the Department of Physics, Chemistry, and Mathematics, and the Center for Educator Preparation & Certification Services at Alabama A&M University for their continued encouragement and support.