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Feb 2, 2016 - Calculations of Novel Thiosemicarbazones. Brian J. Anderson *, Jerry P. Jasinski, Michael B. Freedman, Sean P. Millikan, Kelly A. O'Rourke.
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Synthesis, Crystal Structural Investigations, and DFT Calculations of Novel Thiosemicarbazones Brian J. Anderson *, Jerry P. Jasinski, Michael B. Freedman, Sean P. Millikan, Kelly A. O’Rourke and Victoria A. Smolenski Department of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA; [email protected] (J.P.J.); [email protected] (M.B.F.); [email protected] (S.P.M.); [email protected] (K.A.O.); [email protected] (V.A.S.) * Correspondence: [email protected]; Tel.: +1-603-358-2560 Academic Editor: Helmut Cölfen Received: 8 January 2016; Accepted: 28 January 2016; Published: 2 February 2016

Abstract: The crystal and molecular structures of three new thiosemicarbazones, 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide monohydrate (1), 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide (2) and 2-[1-(2-hydroxy-4-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide acetonitrile solvate (3), are reported and confirmed by single crystal X-ray diffraction, NMR and UV-vis spectroscopic data. Compound (1), C11 H15 N3 O2 S¨ H2 O, crystallizes in the monoclinic with space group P21 /c, with cell parameters a = 8.2304(3) Å, b = 16.2787(6) Å, c = 9.9708(4) Å, and β = 103.355(4)˝ . Compound (2), C12 H17 N3 O2 S, crystallizes in the C2/c space group with cell parameters a = 23.3083(6) Å, b = 8.2956(2) Å, c = 13.5312(3) Å, β = 91.077(2)˝ . Compound (3), C11 H15 N3 O2 S¨ C2 H3 N, crystallizes in the triclinic P-1 space group with cell constants a = 8.9384(7) Å, b = 9.5167(8) Å, c = 10.0574(8) Å, α = 110.773(7)˝ , β = 92.413(6)˝ , and γ = 90.654(7)˝ . DFT B3LYP/6-31(G) geometry optimized molecular orbital calculations were also performed and frontier molecular orbitals of each compound are displayed. The correlations between the calculated molecular orbital energies (eV) for the surfaces of the frontier molecular orbitals to the electronic excitation transitions from the absorption spectra of each compound have been proposed. Additionally, similar correlations observed among three closely related compounds, (4), 2-[1-(2-hydroxy-4-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide, (5), 2-[1-(2-hydroxy-6-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide acetonitrile monosolvate and (6), 2-[1-(2-hydroxy-6-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide, examining structural differences from the substitution of the methoxy group from the phenyl ring (4, 5, or 6 position) and the substitution of the terminal amine (methyl or ethyl) to their frontier molecular orbital surfaces and from their Density Functional Theory (DFT) molecular orbital energies provide further support for the suggested assignments of the title compounds. Keywords: thiosemicarbazones; crystal structure; hydrogen bonds; B3LYP 6-31(G); DFT molecular orbital calculations; frontier molecular orbitals

1. Introduction Thiosemicarbazones are a versatile class of ligands that bind a metal through a nitrogen and sulfur atom. This class of ligands has been widely studied due to their interesting coordination chemistry, prompting several reviews [1–4]. Metal complexes with thiosemicarbazone ligands have been found to have biological activity including anti-malarial [5] and anti-cancer properties [6]. Studies have also looked at the ability of these complexes to bind DNA [7] and they have even been investigated as biological imaging agents [8]. Additionally, recent research has shown metal thiosemicarbazone complexes to be effective catalysts for Heck couplings [9], hydrogenations [10], and Crystals 2016, 6, 17; doi:10.3390/cryst6020017

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and Hartwig couplings [11]. Due to these areas, there is an interest in developing novel thiosemicarbazone compounds and their metal complexes. we interest report novel the and crystal and Hartwig couplings [11]. Due to these thereHere, is developing an insynthesis developing novel Hartwig couplings [11]. Due to these areas, thereareas, is an interest in thiosemicarbazone structure of three new complexes (1, 2, and 3), as well spectroscopic studies and DFT calculations of thiosemicarbazone compounds and their metal complexes. Here, we report the synthesis and crystal compounds and their metal complexes. Here, we report the synthesis and crystal structure of three new these three complexes along with three other closely related thiosemicarbazones structure of(1, three new3),complexes (1,comparisons 2, and 3),studies aswith welland spectroscopic studies and DFT calculations of complexes 2, and as well spectroscopic DFT calculations of these three complexes whose crystal structures have previously been published (4 [12], 5 [13], and 6 [14]). These structures these three complexes along with comparisons with three other closely related thiosemicarbazones along with comparisons with three other closely related thiosemicarbazones whose crystal structures are similar instructures structure, but vary the 5position of6a[14]). methoxy aryl ring, and either a whose crystal have previously been (4 These [12],group 5 structures [13], on andthe 6are [14]). Thesein structures have previously been published (4in[12], [13],published and similar structure, methyl group on terminal amine as shown in Scheme below. are similar in but vary in the position a methoxy the1 aryl ring, group and either a but varyor inethyl thestructure, position of athe methoxy group onnitrogen, theofaryl ring, andgroup either aonmethyl or ethyl on the methyl or ethyl group on the terminal amine nitrogen, as shown in Scheme 1 below. terminal amine nitrogen, as shown in Scheme 1 below.

Scheme 1. Synthesis of thiosemicarbazones. Scheme 1. Synthesis Synthesis of of thiosemicarbazones. thiosemicarbazones. Scheme 1.

The typical synthesis of thiosemicarbazones is a condensation between a ketone (or aldehyde) and a The typical typical synthesis of thiosemicarbazones is other a condensation between a ketoneand(or thiosemicarbazide. The ofcrystal structures of closely arelated thiosemicarbazones, The synthesis thiosemicarbazones is asome condensation between ketone (or aldehyde) a aldehyde) and a thiosemicarbazide. The crystal structures of some other closely related N-Ethyl-2-[1-(2-hydroxy-4-methylphenyl)ethylidene]hydrazinecarbothioamide [15] and thiosemicarbazide. The crystal structures of some other closely related thiosemicarbazones, thiosemicarbazones, N-Ethyl-2-[1-(2-hydroxy-4-methylphenyl)ethylidene]hydrazinecarbothioamide [15] N-Ethyl-2-[1-(2-hydroxynaphthalen-1-yl)ethylidene] hydrazinecarbothioamide [16], N-Ethyl-2-[1-(2-hydroxy-4-methylphenyl)ethylidene]hydrazinecarbothioamide [15]have also been and and N-Ethyl-2-[1-(2-hydroxynaphthalen-1-yl)ethylidene] hydrazinecarbothioamide [16], have also reported. N-Ethyl-2-[1-(2-hydroxynaphthalen-1-yl)ethylidene] hydrazinecarbothioamide [16], have also been been reported. reported. 2. Results and Discussion 2. Results and Discussion 2. Results and Discussion 2.1. Structural Study of (1), (2) and (3) 2.1. Structural Study of (1), (2) and (3) 2.1. Structural Study of (1), (2) and (3) In this discussion, structural and theoretical comparisons are grouped around pairs of In this discussion, structural and theoretical comparisons are grouped around pairs of compounds are similar in containing a 4-methoxy, 5-methoxy or on the In this that discussion, structural and theoretical comparisons are6-methoxy grouped substitution around pairs of compounds that are similar in containing a 4-methoxy, 5-methoxy or 6-methoxy substitution on the 2-hydroxy-phenyl and either a methyl or ethyl group or on6-methoxy the terminal amine on group, compounds that are ring similar in containing a 4-methoxy, 5-methoxy substitution the 2-hydroxy-phenyl ring and either a methyl or ethyl group on the terminal amine group, respectively, respectively, providing forathree related compounds. 2-hydroxy-phenyl ring responses and either methyl or pairs ethylof group on the terminal amine group, providing responses for three related pairs of compounds. respectively, providing responses for three related pairs of compounds. Numbering of of Structures Structuresin inCrystal CrystalStructure StructureTables Tables Numbering Numbering of Structures in Crystal Structure Tables The numbering numbering system and theoretical data of compounds (1), The system chosen chosentotocompare comparethe thestructural structural and theoretical data of compounds (2) and (3) is based on the template shown below (Scheme 2). In compounds (4), (5) and (6), the The numbering system chosen to compare the structural and theoretical data of compounds (1), (1), (2) and (3) is based on the template shown below (Scheme 2). In compounds (4), (5) and (6), the numbering system of the published structures is translated translated to coincide with the the(4), new data in(6), (1),the (2) (2) and (3) issystem basedof onthe thepublished template structures shown below (Schemeto 2).coincide In compounds (5)data andin numbering is with new (1), (2) and (3). numbering system of the published structures is translated to coincide with the new data in (1), (2) and (3). and (3).

Scheme 2. 2. Numbering Numbering system system for for theoretical theoreticaland andexperimental experimentaldata dataon onthiosemicarbazones. thiosemicarbazones. Scheme Scheme 2. Numbering system for theoretical and experimental data on thiosemicarbazones.

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Figure 11 below, below, shows shows the the Ortep Ortep drawing drawing and and packing packing diagram diagram of of Compound Compound (1): Figure 1 below, shows the Ortep drawing and packing diagram of Compound (1): 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide monohydrate. 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide monohydrate. 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide monohydrate.

(A) (A)

(B) (B)

(C) (C)

Figure 1. (A) ORTEP drawing of (1) showing the atom numbering scheme and 50% probability Figure 1. 1. (A) ORTEP of (1) the atom numbering numbering scheme scheme and and 50% 50% probability probability Figure (A) ellipsoids ORTEP drawing drawing (1) showing showing themolecular atom displacement of non-Hofatoms; (B, C) The packing of (1) viewed along the a axis. displacement ellipsoids of non-H atoms; (B, C) The molecular packing of (1) viewed along the athe axis.a displacement ellipsoids of …non-H atoms; (B, …C) The molecular hydrogen packing ofbonds (1) viewed along …O, O–H N, N–H O intramolecular and weak C–H…S, Dashed lines indicate O–H …N, N–H…O, O–H…O intramolecular hydrogen bonds and weak C–H…S, Dashed lines indicate O–H . . . . . . . . . axis. lines indicate O–H interactions N, N–H O, O–H aO 3D intramolecular hydrogen bondsHydrogen and weak …S intermolecular O, O–H forming supramolecular structure. C–H…Dashed ….S. . intermolecular interactions forming a 3D supramolecular structure. Hydrogen C–H…. .O, . S,O–H . . . S intermolecular C–H C–H O, O–H interactions forming a 3D supramolecular structure. atoms not involved in hydrogen bonding have been removed for clarity. atoms not involved in hydrogen bonding have been removed for clarity. Hydrogen atoms not involved in hydrogen bonding have been removed for clarity.

Figure 2 below, shows the Ortep drawing and packing diagram of Compound (2): Figure 2 below, below, shows the Ortep Ortep drawing drawing and and packing packing diagram diagram of of Compound Compound (2): 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide. 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide. 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide. In (1), C C11H15 N OO2S·H 2O, one molecule and water molecule crystallize in the asymmetric unit, In N333O onemolecule moleculeand andaaawater watermolecule moleculecrystallize crystallizein inthe theasymmetric asymmetric unit, 15N 2 S¨ H 2 O, In (1), (1), C11 11H15 2S·H 2O, one while in (2), C 12 H 17 N 3 O 2 S, a single molecule is present. Bond lengths and angles for both compounds while N33OO2S, singlemolecule moleculeisispresent. present.Bond Bondlengths lengths and and angles angles for both compounds compounds 17N 2 S,aasingle while in in (2), (2), C C12 12H17 are in in normal normal ranges ranges [17] [17] (Table (Table 1). 1). In In (1), (1), the the dihedral dihedral angle angle between between the the mean mean planes planes of of the the phenyl are are in normal ranges [17] (Table 1). In (1), the dihedral angle between the mean planes of the phenyl phenyl ˝ ,forming and hydrazinecarbothioamide hydrazinecarbothioamide group group(N1/N2/C8/S1/N3) (N1/N2/C8/S1/N3) isis2.0(5)°, aa nearly planar planar ring and 2.0(5) forming ring and hydrazinecarbothioamide group (N1/N2/C8/S1/N3) is 2.0(5)°, forming a nearly planar . . . … the crystal, an an N2–H2… O1W intermolecular hydrogen bond in concert with weak molecule. In the O1Wintermolecular intermolecularhydrogen hydrogenbond bondin in concert concert with with aa weak molecule. In the crystal, crystal, an N2–H2 N2–H2 O1W weak . .S1 . S1intermolecular 44(12) ring … interaction along with the C9–N3 fragment an R 4 ring O1W–H1WB intermolecular interaction along with the C9–N3 fragment form an R O1W–H1WB…S1 intermolecular interaction along with the C9–N3 fragment form an R444(12) ring . .N1 … motif structure structure (Figure (Figure1). 1).Additional AdditionalO1–H1 O1–H1.… intramolecular hydrogen bonds involving the N1intramolecular intramolecular hydrogen hydrogen bonds bonds involving the motif structure (Figure 1). Additional O1–H1 N1 the . . . . . . . . . . . . … … … … group alongwith with weak C–HO, O, C–H S andN–H N–H OW,OW–H OW–H S intermolecular hydroxyl weak C–HC–H C–H …O, hydroxyl group groupalong along with weak C–H…SSand and N–H…OW, OW, OW–H…SS intermolecular intermolecular interactions (Table (Table 2) 2) are arealso alsoobserved observedforming formingaathree-dimensional three-dimensional(3D) (3D)supramolecular supramolecularstructure. structure. interactions interactions (Table 2) are also observed forming a three-dimensional (3D) supramolecular structure. In (2) (2) the the dihedral dihedral angle angle between between the the mean mean planes planes of of the the phenyl phenyl ring ring and and In (2) the dihedral angle between the mean planes of the phenyl ring and ˝ group (N1/N2/C8/S1/N3) isis50.3(8)°, forming significantly twisted twisted hydrazinecarbothioamide 50.3(8) ,forming forming aaa significantly hydrazinecarbothioamide group group (N1/N2/C8/S1/N3) (N1/N2/C8/S1/N3) is 50.3(8)°, twisted . .N1 … the crystal, crystal, an anintramolecular intramolecularO1–H1 O1–H1.… hydrogen bond forms aa R22(20) motif p20q molecule. In the N1 hydrogen bond forms ring molecule. In the crystal, an intramolecular O1–H1 N1 hydrogen bond forms a (20) ring motif motif . . . … structure (Figure2). 2). Inaddition, addition, a weakN2–H2 N2–H2 S1 intermolecular interaction, which gives rise to aa structure S1intermolecular intermolecularinteraction, interaction, which structure (Figure (Figure 2). In In addition,aaweak weak N2–H2…S1 gives rise to a … . . O2 (8) ring motif motifalong alongwith withaaweak weakN3–H3 N3–H3. … interaction involving the 5-methoxy oxygen atom, R22 (8) p8q ring O2 interaction involving the 5-methoxy ring motif along with a weak N3–H3 O2 interaction involving the 5-methoxy oxygen atom, forms a two-dimensional (2D) network structure (Table 2). forms forms aa two-dimensional two-dimensional (2D) (2D) network network structure structure (Table (Table2). 2).

(A) (A)

(B) (B)

(C) (C)

Figure 2. (A) ORTEP drawing of (2) showing showing the the atom atom numbering scheme scheme and 50% 50% probability Figure (A) ORTEP ORTEP drawing drawing of (2) (2) Figure 2. 2. (A) of showing the atom numbering numbering scheme and and 50% probability probability displacement ellipsoids of non-H atoms; (B, C) The molecular packing of (2) viewed along the b axis. displacement ellipsoids of non-H atoms; (B, C) The molecular packing of (2) viewed along b displacement ellipsoids of non-H atoms; (B, C) The molecular packing of (2) viewed along the bthe axis. …O …S, N–H …O . . . . . . . . .… intramolecular hydrogen bonds and weak N–H Dashed lines indicate O–H … … axis. Dashed lines indicate O–H O intramolecular hydrogen bonds and weak N–H S, N–H O Dashed lines indicate O–H O intramolecular hydrogen bonds and weak N–H S, N–H O intermolecular interactionsforming forming a 2D network structure. Hydrogen atoms not in involved in intermolecular a 2D structure. Hydrogen atoms not involved hydrogen intermolecular interactions interactions forming a network 2D network structure. Hydrogen atoms not involved in hydrogen bonding have been removed for clarity. bonding been have removed clarity. for clarity. hydrogenhave bonding beenfor removed

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Table 1. Selected crystal and DFT * bond lengths (Å), bond angles (˝ ), and torsion angles (˝ ): (1)–(2). Atoms

Distance, Å

DFT, Å

Distance

DFT, Å

C1-C7 C2-O1 C5-O2 C7-N1 N2-C9 C9-S1 C9-N3 N3-C11

1.4783(16) 1.3646(15) 1.3660(16) 1.2890(16) 1.3626(16) 1.6815(13) 1.3334(16) 1.4522(18)

1.487 * 1.365 * 1.371 * 1.290 * 1.386 * 1.665 * 1.370 * 1.454 *

1.4754(14) 1.3555(13) 1.3809(13) 1.2995(14) 1.3543(13) 1.6903(10) 1.3273(13) 1.4565(14)

1.469 * 1.348 * 1.359 * 1.305 * 1.381 * 1.684 * 1.347 * 1.460 *

(1) C11 H15 N3 O2 S¨ H2 O Atoms

Distance, Å

DFT, Å

Distance

DFT, Å

C1-C7-N1 C8-C7-N1 C7-N1-N2 N1-N2-C9 N2-C9-N3 N2-C9-S1

115.27(10) 125.67(11) 120.44(10) 119.03(10) 113.99(11) 122.47(9)

117.19 * 123.90 * 118.04 * 122.12 * 110.94 * 118.63 *

117.17(9) 123.94(9) 117.28(9) 119.67(9) 116.91(9) 119.56(8)

117.64 * 120.51 * 119.41 * 121.40 * 115.10 * 118.63 *

(2) C12 H17 N3 O2 S Atoms

Distance, Å

DFT, Å

Distance

DFT, Å

C7-N1-N2-C9 C1-C7-N1-N2 N1-N2-C9-N3 N1-N2-C9-S1

´177.40(11) 178.93(10) ´177.90(10) 2.06(15)

173.15 * 179.36 * 174.62 * ´6.78 *

´152.54(10) ´173.28(9) 16.31(15) ´165.17(8)

172.86 * 176.73 * ´14.94 * 166.03 *

* DFT B3LYP 6-31 G(d) geometry optimization calculations for (1) and (2).

Table 2. Hydrogen bond interactions for (1) and (2) (Å and ˝ ). D–H . . . A

d(D–H)/Å

d(H–A)/Å

d(D . . . A)/Å