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Complexes of Propargylamines [RC≡CCH2NC4H8NCH2C≡CR] * Vitthalrao S

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Complexes of Propargylamines [RC≡CCH2NC4H8NCH2C≡CR] * Vitthalrao S Journal of Organometallic Chemistry 897 (2019) 247e253 Contents lists available at ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem Chloropalladated tetranuclear and copper(I) complexes of propargylamines [RC≡CCH2NC4H8NCH2C≡CR] * Vitthalrao S. Kashid, Basvaraj S. Kote, Maravanji S. Balakrishna Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400 076, India article info abstract Article history: The reactions of propargylamines 1,4-bis(3-phenylprop-2-yn-1-yl)piperazine (1)and1,4-bis(3-(trime- Received 14 April 2019 thylsilyl)prop-2-yn-1-yl)piperazine (2)withPdCl2 and CuI is described. 1,4-Bis(3-phenylprop-2-yn-1-yl) Received in revised form 2 piperazine reacts with one equivalent of PdCl2 to afford k -N,N-coordinated complexes [PdCl2{Me3- 3 July 2019 SiC^CCH NC H NCH C≡CSiMe -k2-N,N](3) and [PdCl {Me SiC^CCH NC H NCH C≡CSiMe }-k2-N,N](4). Accepted 5 July 2019 2 4 8 2 3 2 3 2 4 8 2 3 The reactions of 1 and 2 with two equivalents of PdCl yielded rare chloropalladated tetranuclear com- Available online 10 July 2019 2 plexes [Pd4(m-Cl)4(PhC¼C(Cl)CH2NC4H8NCH2(Cl)C¼CPh)2](5) and [Pd4(m-Cl)4(Me3SiC¼C(Cl) CH2NC4H8NCH2(Cl)C¼CSiMe3)2](6), respectively, resulting from the trans nucleophilic addition of chloride Keywords: ^ Acetylene ion onto the electrophilic C C bond. The reactions of 1 and 2 with two equivalents of CuI produced 2-D m ≡ e ≡ m Chloropalladation coordination polymers [{Cu2( -I)}2(PhC C CH2NC4H8NCH2C CPh)]n (7) and [{Cu2( - Coordination polymer I)}2(Me3SiC^CCH2NC4H8NCH2C≡CSiMe3)]n (8), respectively. Similar reactions in 1:1 M ratios produced Propargylamine dimeric complexes [Cu2(m-I)2(PhC≡CCH2NC4H8NCH2C≡CPh)2](9) and [Cu2(m- Molecular structure I)2(Me3SiC^CCH2NC4H8NCH2C≡CSiMe3)2](10), respectively. The structures of compounds 3, 5 and 7 have been established by single crystal X-ray analysis. © 2019 Elsevier B.V. All rights reserved. 1. Introduction workers have reported a series of cis and trans dinuclear chlor- opalladated complexes of propargyl amines and thioethers which Alkynes are very important starting materials in carbonÀcarbon are found to be key intermediates in anti-hydrochlorination of cross coupling [1e5], Diels-Alder cyclization reaction [6e8], metal- unactivated alkynes [16,20,21]. However, to the best of our organic frameworks (MOF's) [9], polymerization reactions [10e14], knowledge, there are no reports on tetranuclear complex formation and also in the preparation of several pincer ligands as substrates in chloropalladation reactions. The propagylamines 1,4-bis(3- [15e18]. Alkynes with functionalities such as amine, ether and phenylprop-2-yn-1-yl)piperazine (1) and 1,4-bis(3-(trimethylsilyl) thioether are excellent precursors in organic and organometallic prop-2-yn-1-yl)piperazine (2) having two propargyl groups as side synthesis (Chart 1)[2,15]. The propargylamines are very useful arms are suitable candidates for the formation of tetranuclear reagents for trapping organometallic intermediates such as chlor- chloropalladated products. Similar coordination behavior is antic- opalladates, carba-palladates and other organometallic species ipated in the reactions of nitrogen donor ligands with copper(I) [16,19e21]. The chloropalladation reaction includes the activation halides [36,37]. Nitrogen donor ligands often form 2-D or 3-D of alkynes, alkenes, cyclopropanes and their conversion into al- polymers [36e39] and many of them find applications in catalysis kenes, substituted chloro-products and breakage of cyclopropane [36,40e42], photoluminescence [43]orfluorescence studies [44]. It ring by transferring the chloride ion (Chart 1, A-E) [9,22e24]. The is anticipated that the propagylamines 1 and 2 having acetylene chloropalladation reactions of active cyclopropane and cyclo- groups can form interesting complexes. In this context, we sought propene have also been extensively studied [1,22,23,25e33]. to look into the reactions of propargylamines with palladium(II) as Chloropalladation is one of the key reactions in pharmaceutical well as copper(I) salts. The details are described in this industries to produce many drug molecules [34,35]. Dupont and co- communication. * Corresponding author. E-mail addresses: [email protected], [email protected] (M.S. Balakrishna). https://doi.org/10.1016/j.jorganchem.2019.07.006 0022-328X/© 2019 Elsevier B.V. All rights reserved. 248 V.S. Kashid et al. / Journal of Organometallic Chemistry 897 (2019) 247e253 Chart 1. Some chloropalladated products and alkynes with various functionalities. 2. Experimental section software. The structures were solved using Olex2 [46] with the ShelXT [47] structure solution program using intrinsic phasing and 2.1. General procedures refined with the ShelXL [48]refinement package using least squares minimization. All non-hydrogen atoms were refined All the reactions were performed under aerobic conditions. All anisotropically. Hydrogen atoms were placed in calculated posi- the solvents were purified by conventional procedures and distilled tions and included as riding contributions with isotropic displace- prior to use. The metal precursors PdCl2 and CuI were purchased ment parameters tied to those of the attached non-hydrogen from Aldrich chemicals and used as received. Compounds 1 and 2 atoms. In case of 5, the structure was refined as a non-merohedral were prepared according to published procedures [45]. twin. There is no twin law as such but the twinning is related to a 180 deg rotation. Component 2 rotated by 179.3018\% around [-0.33 2.2. Instrumentation -0.49 0.81] (reciprocal) or [-0.57 -0.58 0.58] (direct). As far as the omitted reflections are concerned the reflections with error/esd The 1H and 13C{1H} NMR (d in ppm) spectra were obtained from more than 10 and the reflections obscured by the beamstop were either Bruker Avance-400 MHz or Bruker Avance-500 MHz spec- excluded in order to avoid problems related to the better refine- trometer. The spectra were recorded in CDCl3 solution with CDCl3 ment of the data. Crystallographic data (including structures (or DMSO‑d6) as an internal lock; TMS was used as internal stan- dard for 1H and 13C{1H} NMR. Positive values indicate downfield shifts. Mass spectra were recorded on BRUKER mass spectrometer Table 1 using Electron-spray ionization mass spectrometry (ESI-MS) Crystallographic information for compounds 3, 5, and 7. method. The powder X-ray diffraction (PXRD) was carried out on 35 7 EMPYREAN, Malvern Panalytical diffractometer with Cu Ka radia- ¼ Formula C22H22Cl2N2Pd C44H40Cl8N4Pd4 2(CH2Cl2)C11H11CuIN tion (l 1.54184 Å). Data were collected in rectangular sample Formula Weight 491.71 1503.85 347.65 3 holder of dimension of Vol. 0.6 cm i.e. l ¼ 2, b ¼ 1.5, h ¼ 0.2 cm at Crystal System Orthorhombic Triclinic monoclinic 298 K using a scan range (2q/deg.) 5e100. Elemental analyses was Space group Pbcn P-1 P21/c performed using Thermo Quest CE instrumentFLASH EA 1112 se- a [Å] 28.824(3) 9.2998(5) 10.2784(6) b [Å] 7.7381(6) 11.1193(6) 7.0389(4) ries. Melting points of all compounds were determined on a Veego c [Å] 9.4523(9) 12.6899(8) 15.4443(8) melting point apparatus and are uncorrected. a [] 90 94.677(5) 90 b [] 90 96.225(5) 98.372(5) 2.3. X-ray crystallography g [ ] 90 102.646(4) 90 V[Å3] 2108.3(3) 1265.32(13) 1105.46(11) Z41 4 A crystal of each of the compounds in the present work suitable À3 rcalc [gcm ] 1.549 1.953 2.089 À1 for single-crystal X-ray diffraction studies was mounted in a cry- m (Mo-Ka) [mm ] 1.143 2.049 4.727 oloop with a drop of paratone oil and placed in the cold nitrogen F(000) 992 736 664 stream of the kryoflex attachment of the Rigaku Saturn 724þ (4 Â 4 T (K) 150 150 150 2q range, [] 5.45e62.162 4.706e54.994 6.186e61.888 bin mode) diffractometer for compounds mentioned in crystallo- Total no. of reflns 8758 10339 5355 graphic data table. Data were collected at 150 K as shown in crys- No. of indep reflns 3068 10339 3013 tallographic data (Table 1), using graphite-monochromated Mo Ka R 0.0657 0.0671 0.0540 radiation (la ¼ 0.71073 Å) with the u-scan technique. The data wR2 0.1114 0.2136 0.1362 S 1.057 1.183 1.118 were collected and reduced using CrystalClear-SM Expert 2.0 r7 V.S. Kashid et al. / Journal of Organometallic Chemistry 897 (2019) 247e253 249 factors) for the structures reported in this paper have been yn-1-yl)piperazine (0.050 g, 0.163 mmol). A 1:1 solution of deposited with the Cambridge Crystallographic Data Centre: CCDC (dichloromethane and petroleum ether) of 6 stored at room tem- 1909553 (3), 190554 (5) and 190555 (7). perature for 24 h afforded analytically pure product of 6 as brown solid. Yield: 70% (0.073 g). Mp: 236e237 C. Anal. Calcd. for 2.4. Reaction products C32H60Cl8N4Pd4Si4$CH2Cl2: C, 28.15; H, 4.44; N, 3.98. Found: C, À 28.13; H, 4.54; N, 4.07. FT-IR (KBr disk, cm 1): 3677 (w), 3467 (br), 2 2.4.1. Synthesis of [PdCl2{PhC≡CCH2NC4H8NCH2C≡CPh}-k -N,N] (3) 2961 (s), 2181 (m), 1616 (s), 1454 (s), 1428 (s), 1363 (w), 1342 (w), An ethanol solution (10 mL) of 1,4-bis(3-phenylprop-2-yn-1-yl) 1250 (s), 1172 (m), 1090 (s), 1024 (s), 855 (s), 798 (m), 761 (m), 701 piperazine (1) (0.050 g, 0.159 mmol) was added dropwise to a so- (w), 636 (m).
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