193Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... DOI: 10.17344/acsi.2020.6345 Scientific paper Manganese(II) β-Diketonate Complexes with Pyridin-4-one, 3-Hydroxypyridin-2-one and 1-Fluoropyridine Ligands: Molecular Structures and Hydrogen-bonded Networks Anže Čavić and Franc Perdih* Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, P. O. Box 537, SI-1000 Ljubljana, Slovenia * Corresponding author: E-mail: franc.perdih@fkkt.uni-lj.si Received: 08-21-2020 Abstract Manganese(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionate) complexes with pyridin-4-one (pyon), 3-hydroxypyri- din-2-one (hpyon), 1-fluoropyridine (pyF) and methanol were prepared and the solid-state structures were determined by single-crystal X-ray analysis. The coordination of the metal center in all complexes was found to be octahedral. In compounds [Mn(tfpb)2(pyon)2] (1) and [Mn(tfpb)2(hpyon)2] (2) extended hydrogen bonding is present facilitating the formation of a three-dimensional supramolecular structure in 1 and a layered structure in 2 through N–H···O hydrogen bonding enhanced by C–H···O interactions as well as C–F···π interactions. In [Mn(tfpb)2(pyF)2] (3) a layered structure is formed through C–H···O and C–H···F interactions as well as π···π and C–F···π interactions. In [Mn(tfpb)2(MeOH)2] (4) a layered structure is formed through a combination of O–H···O and C–F···π interactions. Keywords: β-Diketonates; manganese; pyridines; crystal structure; π···π interaction 1. Introduction Inorganic–organic hybrids, metal–organic coordi- nation polymers and especially metal–organic frameworks (MOFs) are currently an extremely important topic and an active area of research because of their intriguing architec- tures and topologies,1,2 as well as due to their potential ap- plications in catalysis, chemical separation processes, wastewater treatment, gas storage, magnetism and as sen- sors.3 Control of the solid-state arrangement of molecules within a crystal is the central challenge of materials chem- istry. In metal–organic frameworks and coordination polymers, covalent bonding using bridging organic li- gands for creation of robust polymeric structures is of prime importance. Various kinds of these materials have been designed with special attention dedicated to the ge- ometry of the metal ions as well as flexibility, bridging po- tential and coordination preferences of different organic linkers.1 On the other hand, in inorganic–organic hybrids non-covalent bonds adjust the dimensionality and enable new topologies to arise. Non-covalent forces, such as hy- drogen bonding, C–H···π/F interactions, π···π stacking, and halogen bonding are much weaker compared to the covalent bonds, however, their multitude makes them a powerful tool in the crystal engineering. Also, a great vari- ety of non-covalent donors–acceptors and their numbers, their unique directionality and simple introduction into structures make them a particularly good choice for the construction of self-assemblies. Here we report the influence of pyridin-4-one (4-pyridone; pyon), 3-hydroxypyridin-2-one (hpyon), and 1-fluoropyridine (pyF) ligands on the molecular and su- pramolecular structure in the cases of [Mn(tfpb)2(pyon)2] (1), [Mn(tfpb)2(hpyon)2] (2), [Mn(tfpb)2(pyF)2] (3) com- plexes as well as the structure of [Mn(tfpb)2(MeOH)2] (4), where tfpb is the 4,4,4-trifluoro-1-phenylbutane-1,3-dio- nate (or 4,4,4-trifluoro-3-oxo-1-phenylbutan-1-olate) li- gand. The tfpb ligand was selected because it is not sym- metric and possesses phenyl and trifluoromethyl groups enabling also the formation of C−H···F, F···F and C−F···π interactions besides the π···π and C−H···π interactions.4 Pyridin-4-on and 3-hydroxypyridin-2-one were selected since the tautomeric equilibrium between the lactam and lactim forms enables various coordination modes and also 194 Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... due to their different hydrogen bond formation abilities when coordinated in lactam/lactim form. On the other hand, 1-fluoropyridine was selected in order to be able to study the influence of an additional fluorine substituent on the formation of supramolecular aggregation in the ab- sence of the competing strong hydrogen bond donors. 2. Experimental 2. 1. Materials and Characterization Reagents and chemicals were obtained as reagent grade from commercial sources and were used as pur- chased without any further purification. [Mn(tfpb)2(H2O)2] was prepared according to the literature procedure.5 Infra- red (IR) spectra (4000–600 cm−1) of the samples were re- corded using a Perkin–Elmer Spectrum 100, equipped with a Specac Golden Gate Diamond ATR as a solid sam- ple support. Elemental (C, H, N) analyses were obtained using a Perkin–Elmer 2400 Series II CHNS/O Elemental Analyzer. 2. 2. Synthesis Synthesis of [Mn(tfpb)2(pyon)2] (1) [Mn(tfpb)2(H2O)2] (0.065 g, 0.125 mmol) was dissolved in acetone (8 mL) and then pyon (0.024 g, 0.250 mmol) was added. The reaction mixture was stirred for 15 min at ~50 °C and then allowed to stand at room tem- perature. Orange crystals suitable for X-ray analysis were obtained after slow evaporation of the solvent over a few days. Yield: 0.036 g, 43%. Anal. Calcd. [Mn(tfpb)2(pyon)2] (C30H22F6MnN2O6) (MW = 675.44): C 53.35, H 3.28, N 4.15; Found C 52.92, H 2.90, N 4.06. IR (ATR, cm–1): 3244w, 3080w, 2663w, 1606s, 1597m, 1573m, 1527m, 1501m, 1471s, 1374m, 1315m, 1283s, 1248m, 1179s, 1127s, 1072m, 1025m, 996m, 939m, 831m, 763m, 717m, 697s, 635m. Synthesis of [Mn(tfpb)2(hpyon)2] (2) [Mn(tfpb)2(H2O)2] (0.065 g, 0.125 mmol) was dis- solved in warm ethanol (12 mL) and then hpyon (0.028 g, 0.250 mmol) was added. The reaction mixture was stirred for 15 min at ~60 °C and then allowed to stand at room temperature. Orange crystals suitable for X-ray analysis were obtained after slow evaporation of the solvent over a few days. Yield: 0.058 g, 66%. Anal. Calcd. [Mn(tfpb)2(h- pyon)2] (C30H22F6MnN2O8) (MW = 707.44): C 50.91, H 3.14, N 3.96; Found C 50.72, H 3.14, N 3.90. IR (ATR, cm–1): 3251w, 3120w, 2958w, 1605m, 1596m, 1570s, 1543m, 1529m, 1491m, 1471m, 1456m, 1419m, 1377m, 1284s, 1251m, 1187s, 1134s, 1058m, 937m, 885m, 761s, 717m, 699s, 635m. Synthesis of [Mn(tfpb)2(pyF)2] (3) [Mn(tfpb)2(H2O)2] (0.065 g, 0.125 mmol) was dis- solved in pyF (2 mL). The reaction mixture was stirred for 15 min at ~60 °C and then allowed to stand at room tem- perature. Orange crystals suitable for X-ray analysis were obtained after slow evaporation of the solvent over a few days. Yield: 0.045 g, 53%. Anal. Calcd. [Mn(tfpb)2(pyF)2] (C30H20F8MnN2O4) (MW = 679.42): C 53.02, H 2.97, N 4.12; Found C 52.55, H 2.81, N 3.99. IR (ATR, cm–1): 3381br, 1609s, 1597m, 1574s, 1532m, 1490m, 1458m, 1318m, 1281s, 1248m, 1182s, 1129s, 1096m, 1075m, 1025w, 941w, 798w, 768m, 718m, 699s, 635s. Synthesis of [Mn(tfpb)2(MeOH)2] (4) [Mn(tfpb)2(H2O)2] (0.065 g, 0.125 mmol) was dis- solved in warm methanol (12 mL) and then pyon (0.024 g, 0.250 mmol) was added. The reaction mixture was stirred for 15 min at ~60 °C and then allowed to stand at room temperature. Orange crystals suitable for X-ray analysis were obtained after slow evaporation of the solvent over a few days. Yield: 0.040 g, 58%. Anal. Calcd. [Mn(tfpb)2 (MeOH)2] (C22H20F6MnO6) (MW = 549.32): C 48.10, H 3.67; Found C 47.94, H 3.38. IR (ATR, cm–1): 2538br, 2421br, 1928w, 1876w, 1644m, 1602m, 1574m, 1350s, 1321m, 1259m, 1228m, 1191s, 1134m, 995s, 934s, 821s, 811s, 748w, 635s. 2. 3. X-ray Crystallography Single-crystal X-ray diffraction data were collected at room temperature (1, 2, 4) or 150 K (3) on a Nonius Kappa CCD diffractometer or an Agilent Technologies Su- perNova Dual diffractometer with an Atlas detector using monochromated Mo-Kα radiation (λ = 0.71073 Å). The data were processed using DENZO6 or CrysAlis Pro.7 The structures were solved by direct methods implemented in SHELXS8 and SIR-979 and refined by a full-matrix least- squares procedure based on F2 with SHELXL.8 All non-hy- drogen atoms were refined anisotropically. All H atoms were initially located in a difference Fourier maps. The hy- drogen atoms on carbon atoms were treated as riding at- oms in geometrically idealized positions. Hydrogen atoms attached to nitrogen and oxygen atoms were refined fixing the bond lengths and isotropic temperature factors as Uiso(H) = kUeq(N,O), where k = 1.5 for OH groups, and 1.2 for NH groups. In 1 and 4 the CF3 groups are disordered over two positions in 0.76(2):0.24(2) and 0.71(3):0.29(3) (in 1) and 0.66(3):0.34(3) (in 4) ratio. In 1 a possible pseu- do-translation was detected, however, no additional space group could be found using the Platon program. The crys- tallographic data are listed in Table 1. 3. Results and Discussion Initial attempts to prepare 1 using methanol as a sol- vent gave 4 as the sole product. Thus, in the subsequent attempts of its synthesis other solvents were used instead. Compounds 1 and 2 were obtained by the reaction of 195Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... [Mn(tfpb)2(H2O)2] and the corresponding heteroaromatic ligands pyridine-4-on (pyon) and 3-hydroxypyridine-2-on (hpyon) in 1:2 molar ratio in warm ethanol or acetone, re- spectively. Compound 3 was prepared by the reaction of [Mn(tfpb)2(H2O)2] in warm 1-fluoropyridine (pyF) acting as a solvent and as a ligand. Crystals suitable for X-ray analyses were obtained by slow evaporation of the solvent at room temperature over a few days. The IR spectrum of 1 shows two bands at 3244 and 3080 cm–1 and the spectrum of 2 two bands at 3251 and 3120 cm–1 that suggest the in- volvement of the O–H and N–H groups of pyridone li- gands in strong hydrogen bonding. The spectrum of 4 shows one broad band at 3381 cm–1 that suggests the in- volvement of the O–H groups of methanol ligands in strong hydrogen bonding. In all four compounds, there are bands in the frequency range 1609–1527 cm–1 characteris- tic for the ν(C=O) and ν(C=C) stretching of the tfpb li- gand. Compound 1 crystallizes in the monoclinic P21/n space group. Selected bond distances and angles of 1 are summarized in Table 2. The asymmetric unit contains two crystallographically independent half-molecules (A and B), with both independent MnII atoms sitting on the inver- sion centers. Both manganese(II) atoms are octahedrally coordinated (Fig. 1). In the equatorial plane, both metal centers are surrounded by four oxygen atoms of two che- lating tfpb ligands in a trans arrangement, with Mn–O dis- tances 2.1365(14) and 2.1233(13) Å (for A) and 2.1245(13) and 2.1467(13) Å (for B). The Mn(tfpb)2 fragments deviate from planarity, the angle between the mean plane formed by the equatorial MnO4 core and that of the tfpb chelate C3O2 moiety being 14.48(6) and 16.47(6)°. In both com- plexes the axial positions are occupied by two pyon ligands bonded to the metal center through the O atom, with Mn1–O3 distance of 2.2358(12) Å and Mn1–O3–C23 an- gle of 131.10(11)° and Mn2–O6 distance of 2.2035(12) Å and Mn2–O6–C28 angle of 126.58(11)°. These distances are similar to those reported for the three known Mn com- plexes with tfpb.10 The pyon ligands are inclined toward the tfpb moiety. The angle between the plane of the pyon ring and the plane of the equatorial MnO4 core deviates from 90° being 78.60(5)° (for A) and only 44.51(5)° (for B). Superposition of both complexes shows that pyon ligands are oriented in the opposite direction (Fig. 2) with pyon ring in complex B inclined toward the phenyl ring of the tfpb ligand. Complex A is stabilized by an intramolecular C22–H22···O2i interaction between pyon and tfpb ligand (Table 3) and C1–F3a/b···π interactions between –CF3 group and pyon ring with F···Cg3 distances of 3.769(10) and 3.82(4) Å and C–F···Cg3 angles of 130.4(5) and 128(3)°, respectively, where Cg3 is N1/C21–C25 ring cen- troid (Fig. 3). Complex B is stabilized by an intramolecular Table 1. Crystallographic and refinement data for 1–4. Parameter [Mn(tfpb)2(pyon)2] [Mn(tfpb)2(hpyon)2] [Mn(tfpb)2(pyF)2] [Mn(tfpb)2(MeOH)2] (1) (2) (3) (4) Formula C30H22F6MnN2O6 C30H22F6MnN2O8 C30H20F8MnN2O4 C22H20F6MnO6 Mr 675.43 707.43 679.42 549.32 T (K) 293(2) 293(2) 150(2) 293(2) Crystal system Monoclinic Triclinic Monoclinic Triclinic Space group P21/n P–1 P21/c P–1 a (Å) 16.1805(3) 7.3146(2) 11.8720(3) 10.4921(4) b (Å) 10.5318(2) 9.9367(2) 8.8105(2) 10.5763(4) c (Å) 17.8217(3) 10.7440(2) 14.5507(4) 12.4197(5) α(°) 90 108.132(2) 90 70.893(2) β (°) 91.558(2) 100.589(2) 108.628(3) 66.685(2) γ (°) 90 91.833(2) 90 82.624(2) Volume (Å3) 3035.87(10) 726.16(3) 1442.24(7) 1195.92(8) Z 4 1 2 2 Dcalc (Mg/m3) 1.478 1.618 1.565 1.525 μ (mm–1) 0.517 0.549 0.549 0.634 F(000) 1372.0 359.0 686.0 558.0 Crystal size (mm) 0.5 × 0.2 × 0.1 0.6 × 0.6 × 0.5 0.2 × 0.2 × 0.05 0.25 × 0.1 × 0.03 Reflections collected 28841 5959 13789 9395 Data/restraints/parameters 6949/2/471 3298/2/220 3311/0/205 5457/2/353 Rint 0.0322 0.0133 0.0333 0.0291 R, wR2 [I>2σ(I)]a 0.0416, 0.1040 0.0328, 0.0882 0.0399, 0.0961 0.0459, 0.1073 R, wR2 (all data)b 0.0650, 0.1162 0.0352, 0.0904 0.0529, 0.1037 0.0812, 0.1264 GOF, Sc 1.051 1.074 1.044 1.012 Max/min Δρ (e/Å3) 0.21/–0.21 0.31/–0.34 0.83/–0.27 0.32/–0.27 a R = ∑||Fo| – |Fc||/∑|Fo|. b wR2 = {∑[w(Fo2 – Fc2)2]/∑[w(Fo2)2]}1/2. c S = {∑[(Fo2 – Fc2)2]/(n/p)}1/2 where n is the number of reflections and p is the total number of parameters refined. 196 Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... C27–H27···O4ii interaction between pyon and tfpb ligand. The NH groups of the pyon ligands of both independent complexes act as hydrogen-bond donors interacting with the tfpb carbonyl oxygens of the adjacent complexes, facil- itating the formation of a hydrogen-bonded tree-dimen- sional supramolecular structure (Fig. 3). Complex A inter- acts with two complexes B through N1–H1···O6iii bonding enabling the formation of an ABAB chain. Complex B in- teracts with two complexes A through N2–H2···O3 bond- ing enhanced by C26–H26···O1i interaction with R22(7) ring motif11 enabling the formation of an ABAB chain in the second dimension. Furthermore, complex B interacts with two adjacent complexes B through the centrosym- metric C29–H29···F6aiv interactions with R22(18) ring mo- tif forming a BBB chain in the third dimension (Table 3). Figure 1. Crystallographically independent molecules in 1. Disorder on CF3 groups has been omitted for clarity. Displacement ellipsoids are drawn at 30% probability level. Figure 2. Superposition of crystallographically independent mole- cules A (green) and B (orange) in 1. Disorder on CF3 groups has been omitted for clarity. Table 2. Selected bond distances and angles for 1. Distance (Å) Mn1–O1 2.1365(14) Mn2–O4 2.1245(13) Mn1–O2 2.1233(13) Mn2–O5 2.1467(13) Mn1–O3 2.2358(12) Mn2–O6 2.2035(12) Angle (°) O1–Mn1–O2 84.10(5) O4–Mn2–O5 85.38(5) O1–Mn1–O2i 95.90(5) O4–Mn2–O5ii 94.62(5) O1–Mn1–O3 85.43(5) O4–Mn2–O6 85.82(5) O1–Mn1–O3i 94.57(5) O4–Mn2–O6ii 94.18(5) O2–Mn1–O3 86.91(5) O5–Mn2–O6 85.20(5) O2–Mn1–O3i 93.09(5) O5–Mn2–O6ii 94.80(5) Symmetry codes: (i) 1 – x, –y, –z; (ii) 1 – x, –y, 1 – z. 197Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... The supramolecular structure is further stabilized also by C11–F4a···π interaction between –CF3 group of complex B and pyon ring of complex A with F···Cg3 distance of 3.806(11) Å and C–F···Cg3 angle of 139.1(5)°. Compound 2 crystallizes in the triclinic P–1 space group. Selected bond distances and angles are summa- rized in Table 4. The asymmetric unit contains one half of the complex, with the MnII atom sitting on the inversion center. Octahedrally coordinated manganese(II) atom is surrounded by four oxygen atoms positioned in the equa- torial plane, stemming from two chelating tfpb ligands in a trans arrangement, with Mn–O distances 2.1132(10) and 2.1218(9) Å (Fig. 4). The Mn(tfpb)2 fragment devi- ates from planarity, the angle between the mean plane formed by the equatorial MnO4 core and that of the tfpb chelate C3O2 moiety being 15.91(4)°. The axial positions are occupied by two hpyon ligands bonded to the metal center through the O3 atom, with Mn1–O3 distance of 2.2768(10) Å and Mn1–O3–C11 angle of 128.19(9)°. The hpyon ligand is inclined toward the tfpb moiety, with the angle between the plane of the hpyon ring and that of the equatorial MnO4 core being 43.25(6)°. The hydroxy group of the hpyon ligand is involved in intramolecular hydro- gen bonding with the tfpb ligand through O4–H4···O1i interaction (Table 3). The NH group of the hpyon ligand acts as a hydrogen bond donor, facilitating the formation of a centrosymmetric hydrogen-bonded motif via N1– H1···O3ii interactions with the ligated carbonyl O3 atom enhanced by C15–H15···O2iv interactions with the graph- set motifs R22(8) and R22(7), respectively (Fig. 5 and Table 3). This interaction is further stabilized by C1–F3···π in- teraction between CF3 group and the hpyon ring with d(F3···Cg3) = 3.2278(17) Å and <(C1–F3···Cg3) = 135.64(11)°, where Cg3 is N1/C11–C15 ring centroid. Consequently, a chain is formed along the a axis. The chains are further connected into layers along the ac plane via centrosymmetric C13–H13···O4iii hydrogen bonding between hpyon CH moiety and the hydroxy group of the adjacent molecule (Fig. 5). There are no sig- nificant π···π interactions. Figure 3. Three-dimensional supramolecular structure in 1 is achieved by hydrogen bonding around a) molecule A and b) molecule B through a series of N1–H1···O6iii, N2–H2···O3, C26–H26···O1i and C29–H29···F6aiv interactions. Blue dashed lines indicate hydrogen bonds. For the sake of clarity, intramolecular interactions, disorder on CF3 groups and H atoms not involved in the motif shown have been omitted. For symmetry codes see Table 3. a) b) Table 3. Hydrogen bonds for 1–4 [Å and °] D–H···A d(D–H) d(H···A) d(D···A) <(DHA) 1 N1–H1···O6iii 0.872(17) 1.854(17) 2.720(2) 172(3) N2–H2···O3 0.888(16) 1.859(17) 2.723(2) 164(2) C22–H22···O2i 0.93 2.36 3.119(3) 139.1 C26–H26···O1i 0.93 2.48 3.322(2) 151.1 C27–H27···O4ii 0.93 2.47 3.206(2) 136.6 C29–H29···F6aiv 0.93 2.47 3.394(7) 175.7 2 O4–H4···O1i 0.814(17) 1.952(18) 2.7495(16) 166(3) N1–H1···O3ii 0.882(14) 2.009(15) 2.8829(15) 170.2(18) C13–H13···O4iii 0.93 2.58 3.4770(19) 162.9 C15–H15···O2iv 0.93 2.42 3.2428(19) 147.3 3 C13–H13···F2ii 0.95 2.42 3.287(3) 151.6 C14–H14···O1iii 0.95 2.58 3.493(3) 161.3 4 O5–H5···O1i 0.822(10) 1.966(14) 2.772(2) 167(4) O6–H6···O3ii 0.813(10) 2.001(13) 2.801(2) 168(4) Symmetry codes for 1: (i) 1 – x, –y, –z; (ii) 1 – x, –y, 1 – z; (iii) –½ + x, ½ – y, –½ + z; (iv) 1 – x, 1 – y, 1 – z; for 2: (i) 2 – x, 2 – y, –z; (ii) 1 – x, 2 – y, –z; (iii) 2 – x, 2 – y, 1 – z; (iv) –1 + x, y, z; for 3: (ii) –x, 1 – y, –z; (iii) x, ½ – y, ½ + z; for 4: (i) 2 – x, 1 – y, 1 – z; (ii) 2 – x, –y, 1 – z. 198 Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... In the solid state, pyridin-4-one and 3-hydroxypyri- din-2-one are in the lactam form.12,13 Also in metal com- plexes the lactam form of both predominates. A search of the Cambridge Structural Database (CSD, Version 5.41, plus updates)14 has revealed 26 entries15 of metal complex- es where pyridin-4-one, in its lactam form, is bonded via O atom also observed in complex 1. However, 9 entries with the lactim form (as 4-hydroxypyridine) bonded via N atom were found in the CSD with Re, Ir, Pt, and Ag16 as well as Cu and Fe.17 This observation can be explained by the Pearson HSAB (hard–soft acid–base) concept18 since soft acids, such as Re, Ir, Pt, and Ag, show a preference for bonding via pyridine N atom (an intermediate base) as op- posed to the –OH group (a hard base). Additionally, 3 en- tries with the lactim form bonded via OH group were also found with Nd, Tb, Dy.19 In metal complexes with 3-hy- droxypyridin-2-on lactam form with monodentate liga- tion via O atom20,21 was found in 9 entries; the same type Table 4. Selected bond distances and angles for 2. Distance (Å) Mn1–O1 2.1132(10) Mn1–O2 2.1218(9) Mn1–O3 2.2768(10) Angle (°) O1–Mn1–O2 84.24(4) O1–Mn1–O2i 95.76(4) O1–Mn1–O3 92.67(4) O1–Mn1–O3i 87.33(4) O2–Mn1–O3 84.40(4) O2–Mn1–O3i 95.60(4) Symmetry code: (i) 2 – x, 2 – y, –z. Figure 4. Structure of 2. Displacement ellipsoids are drawn at the 30% probability level. Intramolecular hydrogen bonding is present- ed by dashed blue lines. was also observed in complex 2. Additionally, 3 entries were found with O,O’-chelating ligation.21,22 However, no entries were found with lactim form (as 2,3-dihydroxypyr- idine) bonded to the metal center. For comparison, metal complexes with pyridine-2-one were more often investi- gated than complexes with pyridin-4-one and 3-hydroxy- pyridin-2-one and a variety of coordination modes has been observed.21,23,24 Compound 3 crystallizes in the monoclinic P21/c space group. Selected bond distances and angles of 3 are summarized in Table 5. Initial attempts to collect XRD data at room temperature failed due to slow decomposi- tion of the crystal when exposed to the air. Most probably 1-fluoropyridine molecule is eliminated from the complex and the crystal lattice is being thus destroyed. Similar loss of pyridine bonded in zinc picolinato complexes has been previously observed.61,62 The asymmetric unit contains one half of the complex, with the MnII atom sitting on the inversion center. The manganese(II) atom in compound 3 is octahedrally coordinated (Fig. 6). In the equatorial plane, MnII atom is surrounded by four oxygen atoms stemming from the two chelating tfpb ligands, being in a trans arrangement, with Mn–O distances 2.1415(14) and 2.1337(14) Å. The Mn(tfpb)2 fragment deviates from pla- narity, the angle between the mean plane formed by the MnO4 core and that of the tfpb chelate C3O2 moiety being 18.00(7)°. The axial positions are occupied by two pyF li- gands bonded to the metal center through the N1 atom, with Mn1–N1 distance of 2.3425(17) Å. PyF ligand plays the main role in the formation of a layered structure due to the absence of the competing strong hydrogen bond donors. As a hydrogen bond donor PyF is involved in C14–H14···O1iii interaction with carbonyl oxygen atom and in centrosymmetric C13–H13···F2ii interactions with fluorine atom of –CF3 group of tfpb ligands of the adja- cent complexes (Fig. 7 and Table 3). Thus, each complex is involved in eight hydrogen bonds with six adjacent com- plexes forming a layered structure. 2D structure is sup- ported by centrosymmetric π···π interactions between ad- jacent pyF rings with centroid-to-centroid distance of 3.9403(14) Å, perpendicular distance between rings of 3.2624(10) Å and ring slippage of 2.210 Å. Layered struc- ture is further supported also by C–F···π interactions be- tween pyF fluorine atom and pyF aromatic ring with d(F4···Cg3) = 3.6714(19) Å and <(C11–F4···Cg3) = 75.63(13)° as well as by interactions between –CF3 group and benzene ring of tfpb ligand with d(F2···Cg4) = 3.715(2) Å and <(C1–F2···Cg4) = 126.72(15)°, where Cg3 and Cg4 are N1/C11–C15 and C5–C10 ring centroids, respectively (Fig. 7). The inclination of pyon and hpyon ligands toward the tfpb moiety in 1 and 2 is best compared with the com- pound 3 since the ligation of pyF via N atom cannot enable much deviation in comparison to the pyon and hpyon li- gands bonded via O atom. Superposition of both crystallo- graphically independent molecules in 1 as well as mole- 199Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... Figure 5. a) Hydrogen-bonded layer along the ac plane in 2 is formed by b) centrosymmetric N1–H1···O3ii, C15–H15···O2iv and C1–F3···Cg3ii inter- actions and c) C13–H13···O4iii interactions; d) packing of layers (arbitrary colors). Blue and green dashed lines indicate hydrogen bonds and C–F···π interactions, respectively. For the sake of clarity, H atoms not involved in the motif shown have been omitted. For symmetry codes see Table 3. a) b) c) d) Figure 6. Structure of 3. Displacement ellipsoids are drawn at 50% probability level. 200 Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... case of molecule B in 1 and molecule 2 also the phenyl rings of tfpb are evidently inclined toward pyridone moi- eties. Compound 4 crystallizes in the triclinic P–1 space group. Selected bond distances and angles of 4 are summa- rized in Table 6. The asymmetric unit contains one complex molecule with cis-octahedral arrangement of methanol li- gands on the manganese(II) central atom (Fig. 9). Two methanol ligands are bonded to the metal center with Mn1–O5 and Mn1–O6 distances of 2.1714(18) and 2.173(2) Å, respectively, and O5–Mn1–O6 angle of 88.54(8)°. The Mn1–O bond lengths with four oxygen at- oms of the two chelating tfpb ligands are asymmetric with the longer ones of 2.1821(18) and 2.1751(17) Å at the triflu- oromethyl substituent and the shorter ones of 2.1266(18) and 2.1315(18) Å at the phenyl substituent. The Mn(tfpb) fragments deviate from planarity, the tfpb ligands being in- Figure 7. a) Hydrogen-bonded layer along the ac plane in 3 is formed by C13–H13···O1iii and centrosymmetric C14–H14···F2ii interactions as well as centrosymmetric π···π interactions and C–F···π interactions; b) packing of layers (arbitrary colors). Blue and green dashed lines indicate hydrogen bonds and π···π and C–F···π interactions, respectively. For the sake of clarity, H atoms not involved in the motif shown have been omitted. For sym- metry codes see Table 3. Table 5. Selected bond distances and angles for 3. Distance (Å) Mn1–N1 2.3425(17) Mn1–O1 2.1415(14) Mn1–O2 2.1337(14) Angle (°) N1–Mn1–O1 94.36(6) N1–Mn1–O1i 85.64(6) N1–Mn1–O2 88.31(6) N1–Mn1–O2i 91.69(6) O1–Mn1–O2 85.12(5) O1–Mn1–O2i 94.88(5) Symmetry code: (i) –x, –y, –z. b) a) cules 2 and 3 is presented in Fig. 8. Pyon and hpyon ligands are inclined toward the tfpb moiety by 78.60(5)° (molecule A in 1), 44.51(5)° (molecule B in 1) and 43.25(6)° (2) rep- resenting a substantial deviation from 90°. However, in the 201Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... Figure 8. Two views on superposition of crystallographically independent molecules A (green) and B (orange) in 1, 2 (blue) and 3 (violet). Disorder on CF3 groups has been omitted for clarity. Figure 9. Structure of 4. Disorder on both CF3 groups has been omitted for clarity. Displacement ellipsoids are drawn at 30% prob- ability level. Figure 10. a) Hydrogen-bonded chain along b axis in 4 formed by centrosymmetric O5–H5···O1i and O6–H6···O3ii interactions; b) chains are linked into a layer through C–F···π interactions. Blue and green dashed lines indicate hydrogen bonds and C–F···π interac- tions, respectively. For the sake of clarity, H atoms not involved in the motif shown have been omitted. For symmetry codes see Table 3. a) b) 202 Acta Chim. Slov. 2021, 68, 193–204 Čavić and Perdih: Manganese(II) β-Diketonate Complexes ... clined by 25.94(8) and 23.51(8)°. Each methanol ligand is involved in a centrosymmetric hydrogen-bonded motif via O5–H5···O1i and O6–H6···O3ii interactions with the car- bonyl oxygen atom at the trifluoromethyl substituent of the adjacent complex. Both centrosymmetric hydrogen bonds have the graph-set motif R22(8) (Fig. 10 and Table 3) and enable the formation of a hydrogen-bonded chain along the b axis. A centrosymmetric C1–F3···π interaction be- tween CF3 group and the benzene ring of tfpb ligand of the adjacent molecule is present with d(F3···Cg3) = 3.661(4) Å and <(C1–F3···Cg3) = 121.9(3)°, where Cg3 is C5–C10 ring centroid, connecting chains into a layer along the bc plane (Fig. 10). There are no significant π···π interactions. is formed through C–H···O and C–H···F interactions as well as π···π and C–F···π interactions. In 4 a layered struc- ture is formed through a combination of O–H···O and C–F···π interactions. Supplementary Material CCDC 2024368–2024371 (1–4) contain the supple- mentary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crys- tallographic Data Centre via www.ccdc.cam.ac.uk/data_ request/cif. Acknowledgment Financial support from the Slovenian Research Agency through the grant P1–0230–0175 is gratefully ac- knowledged. We thank EN–FIST Centre of Excellence, Dunajska cesta 156, 1000 Ljubljana, Slovenia for using the Supernova diffractometer. 5. References 1. C. B. Aakeröy, N. R. Champness, C. Janiak, CrystEngComm 2010, 12, 22–43. DOI:10.1039/B919819A 2. M. G. Goesten, F. Kapteijn, J. Gascon, CrystEngComm 2013, 15, 9249–9257. DOI:10.1039/c3ce41241e 3. (a) J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang, C.-Y. Su, Chem. Soc. Rev. 2014, 43, 6011–6061; DOI:10.1039/C4CS00094C (b) A. Dhakshinamoorthy, H. Garcia, Chem. Soc. Rev. 2014, 43, 5750–5765; DOI:10.1039/C3CS60442J (c) A. Herbst, C. Janiak, CrystEngComm 2017, 19, 4092–4117; DOI:10.1039/C6CE01782G (d) M. D. Allendorf, V. Stavila, CrystEngComm 2014, 17, 229–246; DOI:10.1039/C4CE01693A (e) T. Stolar, K. Užarević, CrystEngComm 2020, 22, 4511– 4525; DOI:10.1039/D0CE00091D (f) A. Dhakshinamoorthy, A. M. Asiri, H. García, Angew. Chem. 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Distance (Å) Mn1–O1 2.1821(18) Mn1–O2 2.1266(18) Mn1–O3 2.1751(17) Mn1–O4 2.1315(18) Mn1–O5 2.1714(18) Mn1–O6 2.173(2) Angle (°) O1–Mn1–O2 82.45(7) O1–Mn1–O3 89.13(7) O1–Mn1–O4 91.80(7) O1–Mn1–O5 92.79(7) O1–Mn1–O6 171.30(7) O2–Mn1–O3 92.40(7) O2–Mn1–O4 172.98(7) O2–Mn1–O5 94.84(8) O2–Mn1–O6 88.87(7) O3–Mn1–O4 83.46(7) O3–Mn1–O5 172.69(7) O3–Mn1–O6 90.62(7) O4–Mn1–O5 89.43(7) O4–Mn1–O6 96.81(8) O5–Mn1–O6 88.54(8) 4. Conclusion We have prepared and structurally characterized four manganese(II) bis(4,4,4-trifluoro-1-phenylbutane- 1,3-dionate) complexes with pyon, hpyon, pyF and metha- nol ligands. In all prepared compounds the coordination of the metal center is octahedral. Complexes 1–3 possess trans arrangement of ligands while in complex 4 the ar- rangement is cis. In 1–3 the Mn(tfpb)2 fragments deviate from planarity, the angles between the mean planes formed by the equatorial MnO4 cores and that of the tfpb chelate C3O2 moieties being in the range 14.48(6)–18.00(7)°. 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Pri [Mn(tfpb)2(pyF)2] (3) je prisotna plastovita struktura z C–H···O in C–H···F interakcijami ter tudi z π···π in C–F···π interakcijami. Pri [Mn(tfpb)2(MeOH)2] (4) je prisotna plastovita struktura s kombinacijo O–H···O in C–F···π interakcij. Except when otherwise noted, articles in this journal are published under the terms and conditions of the  Creative Commons Attribution 4.0 International License