Hydrogen bonding in basic copper salts: a spectroscopic study of malachite, Cu2(OH)2CO3, and brochantite, Cu4(OH)6SO4

Abstract

Abstract. Infrared and Raman spectra of the basic copper salts malachite, Cu2(OH)zCOs, and brochantite, Cu4(OH)6SO4, as well as of deuterated and 13C substituted samples are presented and discussed in terms of group theory and the hydrogen bonds present. The main results are that (i) the hydrogen donor strengths of the OH-ions are strongly increased due to the very great synergetic effect of the copper ions, (ii) the acceptor strengths of the H-bond acceptor groups (SO ]-, CO 2-, and OH-ions) are significantly modified by the linkage and coordination of the acceptor atoms -this complicates true assignment of the OH bands observed to the two and six different OH-ions present in malachite and brochantite, respectively -, and (iii) the Cu-O stretching modes at 430-590 cm -1 and 420-520 cm -1 for malachite and brochantite, respectively, exhibit strong, partially covalent Cu-O bonding.

Cu,Zn-based catalysts for methanol synthesis: On the effect of calcination conditions and the part of residual carbonates

“…A third feature of the AU series at 1058 cm -1 can be attributed to a symmetric stretching vibration of carbonate (ν 1 ), which is theoretically expected for malachite samples at 1085 cm -1 according to literature [31]. The absence of the symmetric stretching vibration band in case of the calcined ZM samples further supports the assumption, that these carbonates are very weakly bound, in a symmetric environment inside the samples as it is the case for free carbonate-ions where this vibration is IR-inactive, due to the lack of dipole change during the vibration.…”

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

“…[25] The spectrum of the mineral malachite exhibits three strong OH libration bands at 1097, 1048 and 876 cm -1 . According to Schmidt at al., [20] the symmetric C-O stretching vibration of carbonate (ν 1 ), which is IR active due to the lowered symmetry for coordinated carbonate, is expected at 1085 cm -1 but masked by the strong OH deformation bands. The carbonate modes ν 2 and ν 4 (out-of-plane and asymmetric O-C-O bending, respectively) are observed as a sharp band at 817 cm -1 and a triplet at around 750 cm -1 , respectively.…”

“…The spectrum of malachite shows a typical splitting into two modes at 3318 and 3407 cm -1 , which is attributed to the two crystallographically different OH groups. [20] The O-H bands for rosasite are less intense and the splitting is strongly enhanced to 251 cm -1 . A correlation between the splitting of these O-H stretching bands and the degree of Zn incorporation in the malachite structure has been reported in the literature.…”

Local electrochemical investigation of copper patina

“…4b) [30,31]. Within 2 days a brochantite layer begins to grow on top of the cuprite layer, and covers totally the surface after 7 days.…”