TY - JOUR

T1 - Mixed-Ligand Precursors for the Preparation of MgF2 Films: Effect of the Fluorinated Substitute on the Structure and Thermal Properties

AU - Rikhter, E. A.

AU - Lee, X.

AU - Vikulova, E. S.

AU - Kochelakov, D. V.

AU - Korolkov, I. V.

AU - Khrustalev, V. N.

AU - Gao, E.

AU - Morozova, N. B.

N1 - This work was funded by the Russian Science Foundation (project No. 21-73-00252). Публикация для корректировки.

PY - 2023/7

Y1 - 2023/7

N2 - New magnesium complexes [Mg(H2O)2(ofhac)2] 1 and [Mg(tmeda)(ofhac)2] 2 (ofhac = CF3C(O)CHC(O)C2|F-5 , tmeda = N,N,N′,N′-tetramethylethylenediamine) with a 1,1,1,2,2,6,6,6-octafluorohexane-3,5-dionate ligand are prepared. The composition of these compounds is confirmed by elemental analysis and IR spectroscopy, the structure is determined by XRD. The coordination environment of magnesium is distorted octahedral in both complexes. The ofhac ligands are coordinated in the bidentate-cyclic mode; the lengths of Mg–O bonds are similar and vary within 2.033(14)-2.063(18) Å. The aqua ligands in 1 occupy cis positions (d(Mg–O) = 2.0511(18) Å, θ(O–Mg–O) = 85.0(1)°) and participate in the system of O–H…O and O–H…F hydrogen bonds forming a chain packing. The tmeda ligand in 2 performs a chelating function (d(Mg–N) = 2.212(4) Å, θ(N–Mg–N) = 81.0(6)°). The dependence of the structure and the thermal properties of the complexes on the size of the fluorinated substituent (C2F5 instead of CF3) is estimated by comparing the complex with its analogues bearing 1,1,1,5,5,5-hexafluoro-2,4-pentadionate ligands. The crystal structures of [Mg(H2O)2(L)2] are homeotypic; the analogues of [Mg(tmeda)(L)2] crystallize in different space groups. The absence of trans isomers in [Mg(H2O)2(L)2] is confirmed by powder XRD. The thermogravimetry experiments in flowing helium and sublimation tests in vacuum showed that complexes with the ofhac ligand are more volatile. Introducing a C2F5 groups into the ligand also decreases the melting point of the compounds, more significantly for aqua complexes.

AB - New magnesium complexes [Mg(H2O)2(ofhac)2] 1 and [Mg(tmeda)(ofhac)2] 2 (ofhac = CF3C(O)CHC(O)C2|F-5 , tmeda = N,N,N′,N′-tetramethylethylenediamine) with a 1,1,1,2,2,6,6,6-octafluorohexane-3,5-dionate ligand are prepared. The composition of these compounds is confirmed by elemental analysis and IR spectroscopy, the structure is determined by XRD. The coordination environment of magnesium is distorted octahedral in both complexes. The ofhac ligands are coordinated in the bidentate-cyclic mode; the lengths of Mg–O bonds are similar and vary within 2.033(14)-2.063(18) Å. The aqua ligands in 1 occupy cis positions (d(Mg–O) = 2.0511(18) Å, θ(O–Mg–O) = 85.0(1)°) and participate in the system of O–H…O and O–H…F hydrogen bonds forming a chain packing. The tmeda ligand in 2 performs a chelating function (d(Mg–N) = 2.212(4) Å, θ(N–Mg–N) = 81.0(6)°). The dependence of the structure and the thermal properties of the complexes on the size of the fluorinated substituent (C2F5 instead of CF3) is estimated by comparing the complex with its analogues bearing 1,1,1,5,5,5-hexafluoro-2,4-pentadionate ligands. The crystal structures of [Mg(H2O)2(L)2] are homeotypic; the analogues of [Mg(tmeda)(L)2] crystallize in different space groups. The absence of trans isomers in [Mg(H2O)2(L)2] is confirmed by powder XRD. The thermogravimetry experiments in flowing helium and sublimation tests in vacuum showed that complexes with the ofhac ligand are more volatile. Introducing a C2F5 groups into the ligand also decreases the melting point of the compounds, more significantly for aqua complexes.

KW - X-ray diffraction analysis

KW - fluorinated precursor

KW - magnesium

KW - thermal analysis

KW - volatility

KW - β-diketonate

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85166270121&origin=inward&txGid=51fb2f61f777cfaa711f097e0b265023

UR - https://www.mendeley.com/catalogue/4d847345-54b5-3bbb-ab80-e3e837b6b551/

U2 - 10.1134/S0022476623070090

DO - 10.1134/S0022476623070090

M3 - Article

VL - 64

SP - 1250

EP - 1260

JO - Journal of Structural Chemistry

JF - Journal of Structural Chemistry

SN - 0022-4766

IS - 7

ER -