metal-organic compounds
cis-{1-Butyl-3-[2-(phenylsulfanyl)ethyl]-4-imidazolin-2-yl-κ2C2,S′}dichloridoplatinum(II)
aSchool of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Guangdong 528458, People's Republic of China
*Correspondence e-mail: yaohg518@126.com
The 2(C15H20N2S)], comprises one PtII ion, one N-heterocyclic carbene(NHC)-thioether ligand and two chloride ions. The PtII ion is four-coordinated by one C atom and one S atom of the NHC-thioether ligand, and by two chloride ions, forming an approximately square-planar geometry. In the crystal, the molecules are linked via C—H⋯Cl and C—H⋯π interactions, forming a layer parallel to the ab plane.
of the title compound, [PtClCCDC reference: 2041081
Structure description
Nitrogen heterocyclic carbene (NHC) exhibits attractive advantages such as simple operation and mild conditions in organic catalytic synthesis (Enders et al., 2007). In addition, as a neutral two-electron donor, NHC is currently regarded as the most effective ligand for the synthesis of new organometallic complexes owing to its unique features (Hahn & Jahnke, 2008; Nelson & Nolan, 2013). The first distinctive characteristic is the strong donor property of NHC ligands, which makes the interaction with metal center closer (Perrin et al., 2001; Chianese et al., 2003). The second one is that NHC can be flexibly modified by introducing functional groups onto the nitrogen atoms of the N-heterocycle ring. Over the past two decades, numerous attempts have been made to construct diverse donor-functionalized NHCs and their organometallic complexes, and N-, O- and P-functionalized NHCs have been developed and applied in organic synthesis, drug discovery and materials science (Kühl, 2007). However, there are still rare investigations of NHC with S-donor complexes (Liu et al., 2017). As soft and electron-rich ligands, thioethers usually have versatile coordination chemistry, and can form strong M—S bonds with the metal center (Bierenstiel & Cross, 2011; Yuan & Huynh, 2012). The development of new organometallic complexes bearing NHC-thioether ligands (Rosen et al., 2013) is thus highly desirable. In recent years, NHC complexes with group 10 metals have received increasing attention because of their catalytic activities. In contrast to complexes of lighter homologues, PtII-NHC complexes have been less well studied. The novel title metal PtII complex combined with an NHC-thioether ligand was designed and synthesized.
The II ion, one NHC-thioether ligand, and two chloride ions. As shown in Fig. 1, the PtII ion is four-coordinated by one C atom and one S atom of the NHC-thioether ligand, and by two chloride ions in a nearly square-planar environment. The thioether side chain coordinates to the PtII atom in a chelating fashion, forming a six-membered ring with a distorted boat conformation. The Pt—C and Pt—S bond lengths are 1.968 (12) and 2.266 (3) Å, respectively, while the C—Pt—S bond angle is 87.93 (11)°. The two Pt—Cl bond lengths are different from each other [Pt1—Cl1 = 2.360 (3) Å and Pt1—Cl2 = 2.329 (3) Å]. In the crystal, molecules are linked via C—H⋯Cl and C—H⋯π interactions (Table 1), forming a layer parallel to the ab plane (Figs. 2 and 3). A weak intramolecular C—H⋯π interaction is also observed.
of the title complex is composed of one PtSynthesis and crystallization
N-Heterocyclic carbene (NHC)-thioether ligand was synthesized by a slight modification of a reported procedure (Liu et al., 2017). Butyl-imidazole and 2-chloroethylbenzene sulfide (molar ratio 1: 1) were dissolved in acetonitrile at 393 K for 2 days to obtain a dark-brown liquid, and then the solvent was removed by evaporation. The residue was washed repeatedly with diethyl ether, and a brownish-yellow solid was obtained.
The title complex was synthesized from the reaction of the NHC-thioether ligand with potassium tetrachloroplatinate. A reaction tube was charged with the NHC-thioether ligand (0.1710 g, 0.576 mM) and 6 ml of acetonitrile. The tube was evacuated and back-filled with nitrogen. Then a solution of potassium tetrachloroplatinate (0.200 g, 0.480 mM) in 2 ml of water was added in the dark. Keeping it in the dark, the reaction mixture was allowed to stir at 353 K for 24 h. The mixture was concentrated in vacuo and purified by silica gel Pale-yellow rectangular crystals were obtained from the solution at room temperature.
Refinement
Crystal data, data collection and structure . The anisotropy of displacement ellipsoid of atom C9 was restrained with ISOR.
details are summarized in Table 2Structural data
CCDC reference: 2041081
https://doi.org/10.1107/S2414314620014339/is5540sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620014339/is5540Isup2.hkl
Data collection: CrysAlis PRO (Rigaku OD, 2015); cell
CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).[PtCl2(C15H20N2S)] | Dx = 2.021 Mg m−3 |
Mr = 526.38 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 6072 reflections |
a = 8.4254 (3) Å | θ = 2.3–29.3° |
b = 10.1535 (4) Å | µ = 8.53 mm−1 |
c = 20.2262 (10) Å | T = 100 K |
V = 1730.30 (13) Å3 | Block, colourless |
Z = 4 | 0.12 × 0.11 × 0.09 mm |
F(000) = 1008 |
Rigaku Oxford Diffraction SuperNova, Dual, Cu at zero, AtlasS2 diffractometer | 3045 independent reflections |
Radiation source: micro-focus sealed X-ray tube, SuperNova (Mo) X-ray Source | 2911 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.050 |
Detector resolution: 5.2684 pixels mm-1 | θmax = 25.0°, θmin = 2.0° |
ω scans | h = −9→10 |
Absorption correction: multi-scan (CrysAlisPro; Rigaku OD, 2015) | k = −10→12 |
Tmin = 0.310, Tmax = 1.000 | l = −24→22 |
11246 measured reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.033 | w = 1/[σ2(Fo2) + (0.0237P)2 + 8.5737P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.073 | (Δ/σ)max < 0.001 |
S = 1.10 | Δρmax = 1.27 e Å−3 |
3045 reflections | Δρmin = −0.90 e Å−3 |
190 parameters | Absolute structure: Flack x determined using 1166 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
6 restraints | Absolute structure parameter: −0.020 (7) |
Primary atom site location: dual |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Pt1 | 0.63221 (5) | 0.45155 (4) | 0.36816 (2) | 0.01172 (13) | |
Cl1 | 0.8671 (4) | 0.3701 (3) | 0.41687 (15) | 0.0251 (7) | |
Cl2 | 0.7685 (3) | 0.4970 (3) | 0.27062 (15) | 0.0166 (7) | |
S1 | 0.5012 (4) | 0.3876 (3) | 0.46058 (16) | 0.0132 (6) | |
N1 | 0.3999 (10) | 0.6337 (9) | 0.2997 (5) | 0.013 (2) | |
N2 | 0.2959 (10) | 0.4495 (10) | 0.3301 (5) | 0.013 (2) | |
C1 | 0.4671 (13) | 0.5293 (12) | 0.5109 (6) | 0.017 (3) | |
C2 | 0.3753 (16) | 0.6352 (11) | 0.4903 (6) | 0.022 (3) | |
H2 | 0.324679 | 0.633418 | 0.449406 | 0.027* | |
C3 | 0.3602 (18) | 0.7440 (11) | 0.5317 (6) | 0.023 (3) | |
H3 | 0.301393 | 0.816485 | 0.517916 | 0.027* | |
C4 | 0.4319 (15) | 0.7454 (13) | 0.5932 (7) | 0.026 (3) | |
H4 | 0.421705 | 0.818696 | 0.620501 | 0.031* | |
C5 | 0.5187 (15) | 0.6376 (14) | 0.6141 (7) | 0.028 (3) | |
H5 | 0.565556 | 0.637828 | 0.655695 | 0.034* | |
C6 | 0.5362 (14) | 0.5289 (13) | 0.5730 (6) | 0.023 (3) | |
H6 | 0.594069 | 0.456209 | 0.587208 | 0.028* | |
C7 | 0.2978 (14) | 0.3408 (13) | 0.4385 (6) | 0.017 (3) | |
H7A | 0.270431 | 0.259251 | 0.460755 | 0.021* | |
H7B | 0.225027 | 0.408416 | 0.453583 | 0.021* | |
C8 | 0.2785 (13) | 0.3224 (11) | 0.3637 (7) | 0.016 (3) | |
H8A | 0.358118 | 0.261421 | 0.347493 | 0.019* | |
H8B | 0.174644 | 0.285757 | 0.354193 | 0.019* | |
C9 | 0.1750 (14) | 0.5213 (13) | 0.3000 (6) | 0.020 (3) | |
H9 | 0.069889 | 0.495503 | 0.294379 | 0.024* | |
C10 | 0.2414 (14) | 0.6358 (12) | 0.2805 (6) | 0.015 (3) | |
H10 | 0.190345 | 0.703945 | 0.258351 | 0.018* | |
C11 | 0.4343 (14) | 0.5184 (11) | 0.3288 (6) | 0.016 (3) | |
C12 | 0.5054 (15) | 0.7492 (12) | 0.2959 (6) | 0.018 (3) | |
H12A | 0.477671 | 0.801717 | 0.257510 | 0.021* | |
H12B | 0.614370 | 0.719995 | 0.290687 | 0.021* | |
C13 | 0.4914 (14) | 0.8325 (11) | 0.3576 (6) | 0.018 (3) | |
H13A | 0.533278 | 0.783493 | 0.394901 | 0.022* | |
H13B | 0.380163 | 0.850067 | 0.366229 | 0.022* | |
C14 | 0.5803 (14) | 0.9636 (13) | 0.3520 (6) | 0.023 (3) | |
H14A | 0.691832 | 0.946477 | 0.343681 | 0.028* | |
H14B | 0.538795 | 1.012962 | 0.314704 | 0.028* | |
C15 | 0.5640 (17) | 1.0449 (15) | 0.4139 (7) | 0.037 (4) | |
H15A | 0.620925 | 1.126163 | 0.408726 | 0.055* | |
H15B | 0.453847 | 1.063416 | 0.421815 | 0.055* | |
H15C | 0.606756 | 0.996986 | 0.450767 | 0.055* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pt1 | 0.0068 (2) | 0.0125 (2) | 0.0158 (2) | −0.00009 (17) | 0.0003 (2) | −0.0010 (2) |
Cl1 | 0.0119 (14) | 0.0317 (17) | 0.0317 (18) | 0.0032 (16) | −0.0018 (16) | 0.0097 (14) |
Cl2 | 0.0094 (15) | 0.0230 (15) | 0.0174 (16) | −0.0007 (11) | 0.0022 (12) | −0.0003 (12) |
S1 | 0.0116 (15) | 0.0097 (15) | 0.0183 (17) | −0.0005 (11) | 0.0018 (13) | 0.0005 (13) |
N1 | 0.004 (5) | 0.014 (5) | 0.022 (6) | 0.001 (4) | −0.004 (4) | 0.000 (4) |
N2 | 0.010 (3) | 0.012 (3) | 0.016 (3) | 0.000 (2) | −0.001 (2) | 0.001 (2) |
C1 | 0.011 (6) | 0.020 (7) | 0.020 (7) | 0.000 (5) | 0.004 (5) | −0.006 (6) |
C2 | 0.013 (6) | 0.024 (7) | 0.030 (7) | −0.002 (6) | 0.002 (7) | −0.003 (6) |
C3 | 0.029 (7) | 0.010 (6) | 0.029 (8) | 0.005 (6) | 0.002 (7) | −0.003 (5) |
C4 | 0.021 (7) | 0.023 (7) | 0.033 (9) | −0.006 (5) | 0.011 (6) | −0.018 (7) |
C5 | 0.017 (7) | 0.042 (9) | 0.026 (9) | 0.001 (6) | −0.005 (6) | −0.012 (7) |
C6 | 0.013 (7) | 0.025 (8) | 0.032 (8) | 0.007 (5) | −0.004 (5) | 0.000 (6) |
C7 | 0.015 (6) | 0.022 (7) | 0.016 (7) | −0.007 (5) | −0.002 (5) | 0.001 (6) |
C8 | 0.008 (6) | 0.016 (6) | 0.023 (7) | −0.003 (4) | −0.005 (6) | −0.004 (6) |
C9 | 0.012 (7) | 0.031 (8) | 0.018 (7) | 0.005 (5) | −0.012 (5) | −0.005 (6) |
C10 | 0.015 (6) | 0.013 (6) | 0.017 (7) | 0.010 (5) | 0.003 (5) | 0.004 (6) |
C11 | 0.014 (6) | 0.012 (7) | 0.020 (7) | −0.005 (5) | −0.007 (5) | 0.003 (5) |
C12 | 0.013 (7) | 0.022 (7) | 0.018 (7) | 0.003 (5) | 0.002 (5) | 0.010 (6) |
C13 | 0.010 (6) | 0.021 (6) | 0.023 (8) | 0.000 (5) | −0.005 (5) | −0.003 (6) |
C14 | 0.016 (6) | 0.022 (7) | 0.031 (8) | 0.000 (5) | −0.003 (5) | 0.003 (6) |
C15 | 0.039 (8) | 0.024 (7) | 0.047 (9) | −0.001 (7) | −0.017 (7) | 0.007 (8) |
Pt1—Cl1 | 2.360 (3) | C6—H6 | 0.9300 |
Pt1—Cl2 | 2.329 (3) | C7—H7A | 0.9700 |
Pt1—S1 | 2.266 (3) | C7—H7B | 0.9700 |
Pt1—C11 | 1.968 (12) | C7—C8 | 1.533 (18) |
S1—C1 | 1.786 (12) | C8—H8A | 0.9700 |
S1—C7 | 1.834 (12) | C8—H8B | 0.9700 |
N1—C10 | 1.390 (15) | C9—H9 | 0.9300 |
N1—C11 | 1.343 (15) | C9—C10 | 1.349 (17) |
N1—C12 | 1.474 (15) | C10—H10 | 0.9300 |
N2—C8 | 1.465 (15) | C12—H12A | 0.9700 |
N2—C9 | 1.393 (14) | C12—H12B | 0.9700 |
N2—C11 | 1.360 (14) | C12—C13 | 1.513 (17) |
C1—C2 | 1.388 (17) | C13—H13A | 0.9700 |
C1—C6 | 1.385 (17) | C13—H13B | 0.9700 |
C2—H2 | 0.9300 | C13—C14 | 1.532 (16) |
C2—C3 | 1.394 (16) | C14—H14A | 0.9700 |
C3—H3 | 0.9300 | C14—H14B | 0.9700 |
C3—C4 | 1.383 (19) | C14—C15 | 1.507 (18) |
C4—H4 | 0.9300 | C15—H15A | 0.9600 |
C4—C5 | 1.383 (19) | C15—H15B | 0.9600 |
C5—H5 | 0.9300 | C15—H15C | 0.9600 |
C5—C6 | 1.388 (19) | ||
Cl2—Pt1—Cl1 | 90.54 (11) | N2—C8—C7 | 109.9 (10) |
S1—Pt1—Cl1 | 87.93 (11) | N2—C8—H8A | 109.7 |
S1—Pt1—Cl2 | 174.77 (11) | N2—C8—H8B | 109.7 |
C11—Pt1—Cl1 | 179.0 (4) | C7—C8—H8A | 109.7 |
C11—Pt1—Cl2 | 90.4 (4) | C7—C8—H8B | 109.7 |
C11—Pt1—S1 | 91.1 (4) | H8A—C8—H8B | 108.2 |
C1—S1—Pt1 | 108.5 (4) | N2—C9—H9 | 127.0 |
C1—S1—C7 | 101.4 (6) | C10—C9—N2 | 106.0 (10) |
C7—S1—Pt1 | 109.2 (4) | C10—C9—H9 | 127.0 |
C10—N1—C12 | 123.6 (10) | N1—C10—H10 | 126.1 |
C11—N1—C10 | 110.1 (10) | C9—C10—N1 | 107.7 (10) |
C11—N1—C12 | 125.9 (9) | C9—C10—H10 | 126.1 |
C9—N2—C8 | 126.2 (9) | N1—C11—Pt1 | 131.4 (8) |
C11—N2—C8 | 123.2 (9) | N1—C11—N2 | 105.7 (9) |
C11—N2—C9 | 110.5 (10) | N2—C11—Pt1 | 122.8 (8) |
C2—C1—S1 | 122.8 (9) | N1—C12—H12A | 109.5 |
C6—C1—S1 | 116.6 (10) | N1—C12—H12B | 109.5 |
C6—C1—C2 | 120.7 (12) | N1—C12—C13 | 110.8 (10) |
C1—C2—H2 | 120.5 | H12A—C12—H12B | 108.1 |
C1—C2—C3 | 118.9 (12) | C13—C12—H12A | 109.5 |
C3—C2—H2 | 120.5 | C13—C12—H12B | 109.5 |
C2—C3—H3 | 119.7 | C12—C13—H13A | 109.0 |
C4—C3—C2 | 120.7 (12) | C12—C13—H13B | 109.0 |
C4—C3—H3 | 119.7 | C12—C13—C14 | 112.7 (10) |
C3—C4—H4 | 120.1 | H13A—C13—H13B | 107.8 |
C3—C4—C5 | 119.8 (12) | C14—C13—H13A | 109.0 |
C5—C4—H4 | 120.1 | C14—C13—H13B | 109.0 |
C4—C5—H5 | 119.9 | C13—C14—H14A | 109.3 |
C4—C5—C6 | 120.2 (13) | C13—C14—H14B | 109.3 |
C6—C5—H5 | 119.9 | H14A—C14—H14B | 108.0 |
C1—C6—C5 | 119.7 (12) | C15—C14—C13 | 111.7 (11) |
C1—C6—H6 | 120.2 | C15—C14—H14A | 109.3 |
C5—C6—H6 | 120.2 | C15—C14—H14B | 109.3 |
S1—C7—H7A | 109.3 | C14—C15—H15A | 109.5 |
S1—C7—H7B | 109.3 | C14—C15—H15B | 109.5 |
H7A—C7—H7B | 107.9 | C14—C15—H15C | 109.5 |
C8—C7—S1 | 111.8 (8) | H15A—C15—H15B | 109.5 |
C8—C7—H7A | 109.3 | H15A—C15—H15C | 109.5 |
C8—C7—H7B | 109.3 | H15B—C15—H15C | 109.5 |
Pt1—S1—C1—C2 | 62.3 (11) | C8—N2—C9—C10 | 175.0 (11) |
Pt1—S1—C1—C6 | −118.3 (9) | C8—N2—C11—Pt1 | 3.2 (16) |
Pt1—S1—C7—C8 | 14.3 (10) | C8—N2—C11—N1 | −174.1 (10) |
S1—C1—C2—C3 | −177.4 (10) | C9—N2—C8—C7 | −108.8 (12) |
S1—C1—C6—C5 | 178.0 (10) | C9—N2—C11—Pt1 | 178.8 (8) |
S1—C7—C8—N2 | −67.4 (11) | C9—N2—C11—N1 | 1.5 (14) |
N1—C12—C13—C14 | −171.7 (10) | C10—N1—C11—Pt1 | −179.0 (10) |
N2—C9—C10—N1 | −0.9 (13) | C10—N1—C11—N2 | −2.0 (14) |
C1—S1—C7—C8 | 128.8 (9) | C10—N1—C12—C13 | 86.3 (13) |
C1—C2—C3—C4 | −2 (2) | C11—N1—C10—C9 | 1.8 (14) |
C2—C1—C6—C5 | −2.5 (19) | C11—N1—C12—C13 | −85.0 (14) |
C2—C3—C4—C5 | 0 (2) | C11—N2—C8—C7 | 66.0 (14) |
C3—C4—C5—C6 | 1 (2) | C11—N2—C9—C10 | −0.4 (14) |
C4—C5—C6—C1 | 0 (2) | C12—N1—C10—C9 | −170.7 (11) |
C6—C1—C2—C3 | 3.2 (19) | C12—N1—C11—Pt1 | −6.7 (19) |
C7—S1—C1—C2 | −52.6 (11) | C12—N1—C11—N2 | 170.3 (10) |
C7—S1—C1—C6 | 126.8 (10) | C12—C13—C14—C15 | 179.8 (10) |
Cg1 is the centroid of the N1/C10/C9/N2/C11 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···Cl2i | 0.93 | 2.58 | 3.485 (12) | 163 |
C2—H2···Cg1 | 0.93 | 2.98 | 3.828 (13) | 151 |
C14—H14A···Cg1ii | 0.97 | 2.82 | 3.480 (13) | 126 |
Symmetry codes: (i) x−1, y, z; (ii) −x+1, y+1/2, −z+1/2. |
References
Bierenstiel, M. & Cross, E. D. (2011). Coord. Chem. Rev. 255, 574–590. Web of Science CrossRef CAS Google Scholar
Chianese, A. R., Li, X. W., Janzen, M. C., Faller, J. W. & Crabtree, R. H. (2003). Organometallics, 22, 1663–1667. Web of Science CSD CrossRef CAS Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Enders, D., Niemeier, O. & Henseler, A. (2007). Chem. Rev. 107, 5606–5655. Web of Science CrossRef PubMed CAS Google Scholar
Hahn, F. E. & Jahnke, M. C. (2008). Angew. Chem. Int. Ed. 47, 3122–3172. Web of Science CrossRef CAS Google Scholar
Kühl, O. (2007). Chem. Soc. Rev. 36, 592–607. Web of Science PubMed Google Scholar
Liu, Y., Kean, Z. S., d'Aquino, A. I., Manraj, Y. D., Mendez-Arroyo, J. & Mirkin, C. A. (2017). Inorg. Chem. 56, 5902–5910. Web of Science CSD CrossRef CAS PubMed Google Scholar
Nelson, D. J. & Nolan, S. P. (2013). Chem. Soc. Rev. 42, 6723–6753. Web of Science CrossRef CAS PubMed Google Scholar
Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259. Web of Science CrossRef CAS IUCr Journals Google Scholar
Perrin, L., Clot, E., Eisenstein, O., Loch, J. & Crabtree, R. H. (2001). Inorg. Chem. 40, 5806–5811. Web of Science CrossRef PubMed CAS Google Scholar
Rigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England. Google Scholar
Rosen, M. S., Stern, C. L. & Mirkin, C. A. (2013). Chem. Sci. 4, 4193–4198. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Yuan, D. & Huynh, H. V. (2012). Molecules, 17, 2491–2517. Web of Science CrossRef CAS PubMed Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.