Reactivity of Homoleptic Dianionic β-Diketiminato-Supported Yttrium

Apr 18, 2017 - The mixed mono- and dianionic β-diketiminato yttrium complex [η2-N,N-{N(2,6-iPr2C6H3)C(Me)}2CH]Y[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(═C...
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Reactivity of Homoleptic Dianionic β‑Diketiminato-Supported Yttrium Complexes toward CS2: Construction of Neutral or Anionic Dihydropyridinethione Yin Zhang, Jie Zhang,* Qianquan Hong, Linhong Weng, and Xigeng Zhou* Department of Chemistry, Fudan University, Shanghai 200433, People’s Republic of China S Supporting Information *

ABSTRACT: The mixed mono- and dianionic β-diketiminato yttrium complex [η2-N,N-{N(2,6-iPr2C6H3)C(Me)}2CH]Y[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr22,6)] (1) was synthesized in almost quantitive yield by the metathesis reaction of β-diketiminato potassium with YCl3 in a 3:1 molar ratio in THF at room temperature. Complex 1 reacted with 1 equiv of KCH2Ph under the same conditions to afford a linear dianionic β-diketiminato-supported Y(III)/K(I) heterobimetallic polymer {Y[μ-η2:η1-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2-K(THF)3}∞ (2). Moreover, 2 can be transformed into the corresponding salt-type complexes [K([2.2.2]cryptand)]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2Y}− (3) and [nBn4N]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2Y}− (4) in high yields by the reactions of 2 with [2,2,2]-cryptand or nBu4NCl in THF, respectively. The reaction of 3 and 4 with 2 equiv of CS2 in THF at amibent temperature gave the anionic or neutral aryl-substituted dihydropyridinethione [K([2.2.2]cryptand)]+[2-S,4-N(Ar),6-MeC5H2N(Ar)]−·[2-S,4-N(H)Ar,6-MeC5H2N(Ar)] (5) and 2-S,4-N(H)Ar,6-MeC5H2N(Ar) (6) in moderate yields, accompanied by unidentified materials containing Y3+ ions, respectively. The formation of 5 and 6 revealed an intermolecular nucleophilic addition/cyclization and some chemical bond transformations such as C−C and C−N formation, CS cleavage, and 1,3-hydrogen shift occurred in the above reactions. The molecular structures of all of these new complexes 1−6 have been determined through X-ray single-crystal diffraction analysis.

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INTRODUCTION β-Diketiminato ligands continue to be a focus in the organometallic and coordination chemistry1,2 and are capable of exhibiting a variety of coordination modes and a range of donor properties leading to compatibility with a wide range of metal ions from all parts of the periodic table.1−3 Furthermore, these ligands with bulky aromatic groups as the N-substituents can stabilize low valent and/or coordinatively unsaturated metal complexes.4 Among most of these complexes, the β-diketiminato ligands are monoanionic, and usually stable enough for the synthesis of these complexes.5 However, the monoanionic β-diketiminato ligands can be transformed to dianionic or trianionic analogues by reduction or deprotonation under certain conditions.6,7 In contrast to the monoanionic β-diketiminato ligands, the dianionic analogues are highly reactive. For example, Driess et al. reported that dianionic β-diketiminato germylene shows a dipolar character and can react with acetylene and phenylacetylene by C−C coupling or [4 + 2]-cycloaddition.8 Shen et al. also found that dianionic β-diketiminato samarium amide reacted with [HNEt3][BPh4] to form the cationic β-diketiminato samarium amide9b and reacted with aryl nitriles and ketenimine to construct the new modified dianionic β-diketiminato samarium amides by C−C coupling.9a However, to our knowledge, no [5 + 1]-cycloaddition example based on the dianionic β-diketiminato ligand with small molecules has been known. Recently, we have investigated the reactivity of the monoanionic β-diketiminato © XXXX American Chemical Society

rare-earth metal dialkyl complexes toward some aromatic N-heterocycles.10a During the preparation of the dialkyl complexes, we found that small amounts of dianionic β-diketiminato rare-earth metal species had been formed. Herein, we wish to report the synthesis of homoleptic dianionic β-diketiminato rareearth metal complexes and their reactivity toward CS2, revealing that neutral or anionic dihydropyridinethione were constructed by an intermolecular nucleophilic addition/cyclization of the dianionic β-diketiminato ligand with CS2 involving a series of chemical bond transformations such as CS cleavage, C−C and C−N formation, and 1,3-hydrogen shift.

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RESULTS AND DISCUSSION Synthesis and Characterization of Dianionic β-Diketiminato Yttrium Complexes 1−4. Treatment of β-diketiminato potassium with YCl3 in a 3:1 molar ratio in THF at room temperature gave a mixed mono- and dianionic β-diketiminato yttrium complex [η2-N,N-{N(2,6-iPr2C6H3)C(Me)}2CH]Y[η2N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)] (1) in 93% isolated yield, accompanied by the elimination of one neutral β-diketiminato molecule, as shown in Scheme 1. The formation of 1 displayed that a ligand-disproportionation of the Received: December 18, 2016

A

DOI: 10.1021/acs.organomet.6b00941 Organometallics XXXX, XXX, XXX−XXX

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Organometallics Scheme 1. Synthesis of Dianionic β-Diketiminato Yttrium Complexes 1−4

monoanionic β-diketiminato ligand occurred in the above reaction. Complex 1 reacted with 1 equiv of KCH2Ph under the similar conditions to afford a linear homoleptic dianionic β-diketiminato ligand supported Y(III)/K(I) heterobimetallic polymer {Y[μ-η 2 :η 1 -N,N-N(2,6- i Pr 2 C 6 H 3 )C(Me)CHC( CH2)N(C6H3-iPr2-2,6)]2K(THF)3}∞ (2) in 92% isolated yield, indicating that the monoanionic β-diketiminato ligand in 1 can transform into the dianionic analogue via a deprotonation process. Further investigations showed that the polymer 2 can facilely transform into the corresponding salt-type complexes [K([2.2.2]cryptand)]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2Y}− (3) and [nBn4N]+{[η2-N,NN(2,6-iPr2-C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2Y}− (4) in high yields through the reactions of 2 with [2,2,2]cryptand or nBu4NCl in THF at room temperature, respectively. All the new complexes 1−4 have been fully characterized by elemental analysis, and 1H and 13C NMR spectroscopy, which are in good agreement with the proposed structures. Their crystal structures have also been confirmed through the X-ray diffraction analysis method. In the 1H NMR spectrum of 1, two singlets at δ = 5.61 and 5.12 ppm are attributed to the C−H resonances of the skeleton central carbon of mono- and dianionic β-diketiminato ligands, respectively. Three singlets at δ = 1.81, 1.68, and 1.49 ppm are attributed to the resonances of three NC(Me) groups. The methylene group (NC(CH2)) is divided into two singlet groups at δ = 3.77 and 3.21 ppm, which are similar to that of a dianionic β-diketiminato silylene compound {HC(CMeNAr)(C(CH2)NAr)}SiBr2 (Ar = 2,6-iPr2C6H3).11 Furthermore, the 1 H NMR spectra of complexes 2−4 also display that the methylene group is divided into two peaks at δ = 2.91 and 2.21 ppm in 2, 2.93 and 2.21 ppm in 3, and 2.91 and 2.20 ppm in 4, respectively. Complex 1 crystallizes from THF in triclinic system, space group P1̅. Its molecular structure, including the selected bond lengths and angles, are compiled in Figure 1. The X-ray diffraction analysis results show that 1 is a solvent-free monomer

with the Y3+ ion bonded to two η2-coordinated β-diketiminato ligands to form a distorted tetrahedron geometry. The Y−N1 and Y−N2 distances (2.201(4) and 2.225(4) Å) are shorter than the Y−N3 and Y−N4 distances (2.331(4) and 2.337(4) Å),

Figure 1. Molecular structure of 1 with thermal ellipsoids at 30% probability. 2,6-Diisopropyl groups of the β-diketiminato ligand and parts of hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Y1−N1 2.201(4), Y1−N2 2.225(4), Y1−N3 2.331(4), Y1−N4 2.337(4), N3−C31 1.332(6), N4−C45 1.336(6), C31−C30 1.390(7), C45−C30 1.399(7), C31−C32 1.526(7), C45−C46 1.507(7), N1−C2 1.384(6), C16−N2 1.369(6), C16−C17 1.532(7), C16−C1 1.354(7), C2−C1 1.483(7), C2−C3 1.324(7); N1−Y1−N2 95.20(15), N1−Y1−N3 116.39(14), N2−Y1−N3 115.95(15), N1−Y1−N4 122.02(15), N2−Y1−N4 125.28(15), N3−Y1−N4 83.88(14). B

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Figure 2. Chain of the polymeric structure of 2 (top) and view of the repeating unit (bottom). Ellipsoid probability level at 30%. 2,6-Diisopropyl groups of the β-diketiminato ligand and parts of hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Y1−N1A 2.219(2), Y1−N1 2.220(2), Y1−N2 2.260(2), Y1−N2A 2.260(2), K1−O2 2.556(4), K1−O1A 2.657(3), K1−O1 2.657(3), K1−C17 3.226(4), K1−C17A 3.226(4), N1−C16 1.381(4), N2−C2 1.387(4), C1−C2 1.342(4), C1−C16 1.483(4), C2−C3 1.520(4), C16−C17 1.359(5); N1A−Y1−N1 114.17(13), N1−Y1−N2 92.78(8), N1A−Y1−N2A 92.78(8), N2−Y1−N2A 129.40(12), N1A−Y1−C2A 78.30(9), C16−C17−K1 142.3(3).

which might be attributable to the stronger interaction between the dianionic β-diketiminato ligand with the Y3+ ion than that of the monoanionic β-diketiminato ligand with the Y3+ ion. The C2−C3 distance (1.324(7) Å) is a standard CC double bond length.12 The molecular structure of 2 is shown in Figure 2, and reveals that it is a one-dimensional chain through the coordination interactions of the potassium ions with the carbon atoms of the methylene groups from the dianionic β-diketiminato ligands. Its overall structure is very similar to that of the known compound {La[μ-η 2 :η 1 -N,N-N(2,6- i Pr 2 C 6 H 3 )C(Me)CHC(CH 2 )N(C6H3-iPr2-2,6)]2K(THF)4}∞, except for the difference of rareearth metal ion and the number of THF coordinated to the K+ ion.6a In 2, each Y3+ ion is also coordinated with four nitrogen atoms from the two dianionic β-diketiminato ligands to form a distorted tetrahedron geometry. The Y−N1 and Y−N2 distances are 2.220(2) and 2.260(2) Å and are comparable to the corresponding values found in 1 (Y−N1 2.201(4) Å and Y−N2 2.225(4) Å). However, the C16−C17 bond length (1.359(5) Å) is slightly longer than that observed in 1 (C2−C3 1.324(7) Å), which may be attributed to the coordination interactions between the potassium ion with the C17 atom. Consistent with this observation, the K−C17 bond length is 3.226(4) Å and is in the range of the K−C donor bond.6a The molecular structures of 3 and 4 are also shown in Figures 3 and 4, and show that both of them are salt-type complexes, and their anionic parts are very similar. The center metal ions Y3+ are coordinated to four nitrogen atoms from two dianionic β-diketiminato ligands to form a distorted tetrahedron geometry. Their structural parameters also indicated that these β-diketiminato ligands are dianionic, and in the normal range of the dianionic β-diketiminato ligands.

Figure 3. Molecular structure of 3 with thermal ellipsoids at 30% probability. 2,6-Diisopropyl groups of the β-diketiminato ligand and parts of hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Y1−N2 2.236(5), Y1−N3 2.244(5), Y1−N1 2.256(5), Y1−N4 2.276(5), K1−O6 2.780(7), K1−O4 2.781(7), K1−O1 2.791(5), K1−O5 2.799(7), K1−O3 2.820(7), K1−O2 2.850(7), K1−N5 2.956(8), K1−N6 3.049(10), N1−C2 1.390(8), N2−C16 1.437(9), N3−C31 1.312(8), N4−C45 1.330(7), C1−C16 1.309(9), C1−C2 1.488(9), C2−C3 1.351(9), C30−C45 1.334(9), C30−C31 1.509(9), C31−C32 1.338(9), C45−C46 1.527(9); N2−Y1−N3 116.5(2), N2−Y1−N1 93.4(2), N3−Y1−N1 118.0(2), N2−Y1−N4 122.6(2), N3−Y1−N4 91.30(19), N1−Y1−N4 117.45(18).

Reactions of 3 and 4 with CS2. The salt-type complexes 3 and 4 can react with 2 equiv of CS2 in THF at room temperature C

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are almost equivalent, because one hydrogen atom is shared between them through an intermolecular hydrogen bond interaction (N−H···S).13 Consistent with this observation, the 1H NMR spectra of 5 also display that only two single peaks at δ = 5.91 and 5.69 ppm are attributed to the resonances of two C−H bonds of the pyridine rings. Positive structural verification of 6 has also been provided by a single-crystal X-ray diffraction analysis. The molecular structure of 6 (Figure 6) shows that a new planar pyridine ring skeleton has been constructed from the corresponding bond length and angle data. Interestingly, a dimer structure (Figure 6) is formed by two novel pair of intermolecular N−H···S hydrogen-bonding interactions from the N−H bond of the NH group and the sulfur atom of another dihydropyridinethione unit. The C1−S1 distance (1.662(8) Å) is in the range of the CS double bond and is comparable to the corresponding value found in 1,3,5-triaryl,2-pyridinethione (C1−S1 1.680(5) Å).14 This result reveals that the H−N bond is a covalent bond, and the H···S bond is a hydrogen bond in its crystal structure. However, the 1H spectra of 6 in THF-d8 at ambient temperature shows that the two kinds of CH resonances in the pyridine ring were divided into four singlet peaks at δ = 7.01, 6.20, 6.13, and 5.48 ppm in the 1:1:1:1 ratio. The corresponding values in its 13C NMR are found in 112.50, 110.57, 104.51, and 101.86 ppm. This result might suggest that there are two components such as thione (A) and thiol (B) of 6 in solution due to the intermolecular proton shift from the N atoms to the S atoms (Scheme 3). As shown in Scheme 4, we proposed a possible mechanism for the construction of the dihydropyridinethione skeleton. The first step is the nucleophilic addition of the dianionic β-diketiminato ligand with one CS2 molecule to form the intermediate I (C−C coupling).9a Then, the intermediate I undergoes another nucleophilic addition of the nitrogen atom from the β-diketiminato ligand with the center carbon from the CS2 moiety to afford the intermediate II (C−N coupling).10b The neutral and anionic dihydropyridinethione units are formed by C−S bond cleavage and 1,3-hydrogen migration or deprotonation.

Figure 4. Molecular structure of 4 with thermal ellipsoids at 30% probability. 2,6-Diisopropyl groups of the β-diketiminato ligand and parts of hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): Y1−N1 2.234(4), Y1−N1A 2.234(4), Y1−N2 2.272(4), Y1−N2A 2.272(4), N1−C2 1.380(7), N2−C16 1.377(6), C1−C16 1.355(7), C1−C2 1.488(7), C2−C3 1.356(8), C16−C17 1.514(7); N1−Y1−N2 92.16(14), N1−Y1−N2A 114.64(14), N1A−Y1−N2 114.64(14), N1A−Y1−N2A 92.17(14).

to give two structural characterized compounds [K([2.2.2]cryptand)]+[2-S,4-N(Ar),6-(Me)C5H2N(Ar)]−·[2-S,4-N(H)Ar,6-(Me)C5H2N(Ar)] (5) and 2-S,4-N(H)Ar,6-(Me)C5H2N(Ar) (6) in 74% and 32% isolated yields (based on the dianionic β-diketiminato ligand), respectively, as shown in Scheme 2. The formation of 5 and 6 indicated that an intermolecular nucleophilic addition/cyclization and a series of chemical bond transformations such as C−C and C−N formation, CS cleavage, and 1,3-hydrogen shift occurred in the above reactions, and provided a potential route for the constrution of neutral and anionic dihydropyridinethione. Structural determination results (Figure 5) indicated that 5 is a cocrystal compound, which is consistent of netural arylsubstituted dihydropyridinethione 2-S,4-N(H)Ar,6-(Me)C5H2N(Ar) (6) and the deprotonated compound 6 and cationic potassium cryptand [K([2.2.2]cryptand)]+. The structural parameters indicated that the two dihydropyridinethione units

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CONCLUSIONS In summary, a series of the dianionic β-diketiminato yttrium complexes have been synthesized through ligand-disproportionation or deprotonation in high yields. The reactivity of complexes 3 and 4 toward CS2 has also been investigated, and revealed that neutral and anionic dihydropyridinethione have been facilely

Scheme 2. Reactions of 3 and 4 with CS2

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Figure 5. Molecular structure of 5 with thermal ellipsoids at 30% probability. All hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg): C1−C2 1.389(4), C1−N1 1.391(4), C1−S1 1.698(3), C2−C3 1.390(4), C3−N2 1.338(4), C3−C4 1.425(5), C4−C5 1.340(5), C5−N1 1.387(4), C31−C32 1.379(4), C31−N3 1.391(4), C31−S2 1.717(3), C32−C33 1.401(4), C33−N4 1.331(4), C33−C34 1.419(5), C34−C35 1.350(5), C35−N3 1.393(4); C2−C1−N1 116.7(3), C2−C1−S1 124.3(3), N1−C1−S1 119.0(2), C1−C2−C3 124.3(3), N2−C3−C2 126.5(3), N2− C3−C4 118.1(3), C2−C3−C4 115.4(3), C5−C4−C3 121.8(3), C4−C5−N1 120.7(3), C4−C5−C6 121.7(3), N1−C5−C6 117.6(3), C(32)− C(31)−N(3) 118.2(3), C32−C31−S2 123.4(3), N3−C31−S2 118.4(2), C31−C32−C33 123.4(3), N4−C33−C32 125.6(3), N4−C33−C34 119.1(3), C32−C33−C34 115.3(3), C35−C34−C33 122.4(3), C34−C35−N3 120.0(3), C34−C35−C36 122.2(3), N3−C35−C36 117.7(3).

Scheme 3. Two Components such as A and B of 6 in Solution

Scheme 4. A Proposed Mechanism for Construction of the Dihydropyridinethione Skeleton

Figure 6. Molecular structure of 6 with thermal ellipsoids at 30% probability. Selected bond lengths (Å) and angles (deg): C1−C2 1.376(10), C1−N1 1.433(8), C1−S1 1.662(8), C2−C3 1.362(10), C3−N2 1.326(9), C3−C4 1.454(9), C4−C5 1.326(10), C5−N1 1.360(9), C5−C6 1.505(9), N2−H2 0.8600; C2−C1−N1 114.0(6), C2−C1−S1 126.3(6), N1−C1−S1 119.7(5), C3−C2−C1 126.6(7), N2−C3−C2 124.4(7), N2−C3−C4 120.3(7), C2−C3−C4 115.4(6), C5−C4−C3 120.2(7), C4−C5−N1 121.8(6), C4−C5−C6 119.6(7), N1−C5−C6 118.6(6). nitrogen atmosphere in an MBRAUN glovebox. The nitrogen in the glovebox was constantly circulated through a copper/molecular sieves catalyst unit. The oxygen and moisture concentrations in the glovebox atmosphere were monitored by an O2/H2O Combi-Analyzer (MBRAUN) to ensure both were always below 1 ppm. The solvents of THF, toluene, and n-hexane were refluxed and distilled over sodium benzophenone ketyl under nitrogen immediately prior to use. The β-diketiminate ligand10a and KCH2Ph15 were prepared according to the literature methods.

constructed through an intermolecular nucleophilic addition/ cyclization of the dianionic β-diketiminato ligand with CS2.

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EXPERIMENTAL SECTION

General Methods. All reactions were carried out under a dry and inert atmosphere either using standard Schlenk techniques or under a E

DOI: 10.1021/acs.organomet.6b00941 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics YCl3, [2.2.2]-cryptand, [Bu4N]+[Cl]−, and CS2 were purchased from Aldrich and were used without purification. Elemental analyses for C, H, and N were carried out on a Rapid CHN-O analyzer. 1H and 13C NMR data were obtained on an NMR spectrometer (400 MHz for 1H; 100 MHz for 13C). Synthesis of [η2-N,N-{N(2,6-iPr2C6H3)C(Me)}2CH]Y[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)] (1). To a THF solution of β-diketiminate ligand (6.28 g, 15.0 mmol) was added slowly KCH2Ph (1.95 g, 15.0 mmol; dissolved in 25 mL THF) in a roundbottom flask at room temperature. In another round-bottom flask, THF (20 mL) was added to YCl3 (0.976 g, 5.0 mmol), and stirred for 24 h. Then, the THF solution of β-diketiminate potassium in situ was added slowly into the slurry of YCl3(THF)3.5, and the mixtures were stirred for 24 h. Then, the slurry was filtered and the filtrate was concentrated to dryness under vacuum, and washed with n-hexane (3 × 20 mL).The slurry was filtered, and a yellow solid was obtained. A 15 mL portion of THF was added to the powder, and then yellow crystals of 1 suitable for X-ray analysis were obtained from the concentrated THF solution after 3 days. Yield: 4.293 g (93%). 1H NMR (400 MHz, C6D6, RT): δ 7.26− 7.15 (m, 5H, Ar), 7.12−7.04 (m, 4H, Ar), 7.01 (t, J = 7.6 Hz, 1H, Ar), 6.98−6.92 (m, 1H, Ar), 6.90−6.85 (m, 1H, Ar), 5.61 (s, 1H, −CCHC−), 5.12 (s, 1H, −CCHC−), 3.77 (m, 2H, −CHMe2 and −C(CH2)−), 3.39 (m, 1H, −CHMe2), 3.21 (m, 2H, −CHMe2 and −C(CH2)−), 3.05 (m, 2H, −CHMe2), 2.79 (m, 2H, −CHMe2), 2.58 (m, 1H, −CHMe2), 1.81 (s, 3H, −NC(Me)−), 1.68 (s, 3H, −NC(Me)−), 1.59 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 1.49 (s, 3H, −NC(Me)−), 1.41 (m, 6H, −CHMe2), 1.34 (m, 6H, −CHMe2), 1.24 (m, 12H, −CHMe2), 1.09 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 0.98 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 0.90 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 0.71 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 0.63 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2), 0.48 (d, 3 JH‑H = 6.8 Hz, 3H, −CHMe2), 0.39 (d, 3JH‑H = 6.8 Hz, 3H, −CHMe2). 13 C NMR (100 MHz, C6D6, RT): δ 170.1 (s, −NC(Me)−), 166.9 (s, −NC(Me)−), 149.6, 146.6, 145.3, 145.0, 144.8, 143.4, 142.7, 141.9, 141.4, 141.2, 140.7, 126.8, 125.8, 124.8, 124.6, 124.2, 123.8, 123.6, 123.4, 123.1, 122.3, 100.4 (s, −CCHC−), 94.6 (s, −CCHC−), 84.0 (s −C(CH2)−), 31.1 (s, −CHMe2), 28.8 (s, −CHMe2), 28.6 (s, −CHMe2), 28.4 (s, −CHMe2), 28.0 (s, −CHMe2), 27.9 (s, −CHMe2), 27.3 (s, −CHMe2), 27.0 (s, −CHMe2), 26.9 (s, −NC(Me)−), 26.5 (s, −CHMe2), 26.0 (s, −NC(Me)−), 25.8 (s, −CHMe2), 25.5 (s, −CHMe2), 25.4 (s, −CHMe2), 25.2 (s, −CHMe2), 25.1 (s, −CHMe2), 24.9 (s, −CHMe2), 24.8 (s, −CHMe2), 24.7 (s, −NC(Me)−), 24.6 (s, −CHMe2), 24.4 (s, −CHMe2), 24.1 (s, −CHMe2), 23.9 (s, −CHMe2), 23.7 (s, −CHMe2), 22.6 (s, −CHMe2); Elemental Analysis Calcd (%) for C58H81N4Y: C 75.46, H 8.84, N 6.07; found: C 75.19, H 8.79, N 6.22. Synthesis of {Y[μ-η2:η1-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2K(THF)3}∞ (2). A 10 mL THF solution of KCH2Ph (0.065 g, 0.5 mmol) was added slowly to a THF solution (15 mL) of 1 (0.462 g, 0.5 mmol), and stirred for 24 h at room temperature. Then, the solution was evaporated to dryness under vacuum, and washed with n-hexane(3 × 5 mL). The slurry was filtered, and a yellow solid was obtained. Yellow crystals of 2 suitable for X-ray analysis were obtained by recrystallization in THF(3−4 mL) at room temperature. Yield: 0.542 g (92%). 1H NMR (400 MHz, THF-d8, RT): The coordinated THF integral is not listed because of the H/D scrambling results in an inaccurate integral. δ = 7.04 (m, 2H, Ar), 6.92 (m, 2H, Ar), 6.86 (t, J = 6.8 Hz, 2H, Ar), 6.76 (m, 2H, Ar), 6.69−6.62 (m, 4H, Ar), 5.30 (s, 2H, −CCHC−), 3.98 (m, 2H, −CHMe2), 3.75 (m, 2H, −CHMe2), 3.25 (m, 2H, −CHMe2), 3.05 (m, 2H, −CHMe2), 2.91 (d, 4JH‑H = 1.9 Hz, 2H, −CH2C−), 2.21 (d, 4JH‑H = 2.1 Hz, 2H, −CH2C−), 1.75 (s, 6H,− CHC(Me)N), 1.45 (d, 3JH‑H = 6.7 Hz, 6H, −CHMe2), 1.25 (d, 3JH‑H = 6.7 Hz, 6H, −CHMe2), 1.12 (d, 3JH‑H = 6.6 Hz, 6H, −CHMe2), 1.08 (d, 3 JH‑H = 6.8 Hz, 6H, −CHMe2), 1.00 (d, 3JH‑H = 6.7 Hz, 6H, −CHMe2), 0.88 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.37 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.09 (d, 3JH‑H = 6.9 Hz, 6H, −CHMe2). 13C NMR (100 MHz, THF-d8, RT): δ = 156.0 (s, −NC(Me)−), 151.4, 147.9, 147.3, 145.2, 145.1, 144.3, 143.0, 122.8 (s, Ar), 122.7 (s, Ar), 122.2 (s, Ar), 122.1 (s, Ar), 122.0 (s, Ar), 121.1 (s, Ar), 102.5 (s, −CCHC−), 76.7 (s, −CH2C−), 67.3 (s, THF), 29.1 (s, −CHMe2), 27.4 (s, −CHMe2), 27.1 (s, −CHMe2), 27.0 (s, −CHMe2), 26.7 (s, −CHMe2), 26.4 (s, −CHC(Me)N−), 26.3 (s, −CHMe2), 25.5 (s, THF), 25.4 (s, −CHMe2),

25.3 (s, −CHMe2), 24.8 (s, −CHMe2), 24.5 (s, −CHMe2), 23.3 (s, −CHMe2); Elemental Analysis Calcd (%) for C70H104KN4O3Y: C 71.40, H 8.90, N 4.76; found: C 71.08, H 8.76, N 4.62. Synthesis of [K([2.2.2]cryptand)]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC(CH2)N(C6H3-iPr2-2,6)]2Y}− (3). A 5 mL THF solution of [2,2,2]-cryptand (0.113 g, 0.3 mmol) was added slowly to a THF solution (15 mL) of 2 (0.353 g, 0.3 mmol), and stirred for 48 h at room temperature. Then, the solution was concentrated to ca. 3−4 mL. Storing at room temperature for 2 days gave 0.361 g (90%) of 3 as yellow blocks suitable for X-ray crystallography. 1H NMR (400 MHz, THF-d8, RT): δ = 7.04 (m, 2H, Ar), 6.92 (m, 2H, Ar), 6.87 (t, J = 7.6 Hz, 2H, Ar), 6.77 (m, 2H, Ar), 6.71−6.62 (m, 4H, Ar), 5.30 (s, 2H, −CCHC−), 3.98 (m, 2H, −CHMe2), 3.75 (m, 2H, −CHMe2), 3.55 (s, 12H, [2,2,2]cryptand), 3.52 (t, 3JH‑H = 4.6 Hz, 12H, [2,2,2]-cryptand), 3.25 (m, 2H, −CHMe2), 3.06 (m, 2H, −CHMe2), 2.93 (d, 4JH‑H = 1.6 Hz, 2H, −CH2C−), 2.54 (t, 3JH‑H = 4.6 Hz, 12H, [2,2,2]-cryptand), 2.21 (d, 4JH‑H = 2.0 Hz, 2H, −CH2C−), 1.75 (s, 6H, −CHC(Me)N−), 1.46 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 1.25 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 1.13 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 1.09 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 1.01 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.89 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.37 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.09 (d, 3JH‑H = 7.2 Hz, 6H, −CHMe2). 13C NMR (100 MHz, THF-d8, RT): δ = 156.0 (s, −NC(Me)−), 151.4, 147.9, 147.3, 145.2, 145.1, 144.4, 143.0, 122.8 (s, Ar), 122.7 (s, Ar), 122.2 (s, Ar), 122.1 (s, Ar), 122.0 (s, Ar), 121.1 (s, Ar), 102.5 (s, −CCHC−), 76.8 (s, −CH2C−), 70.3 (s, [2,2,2]cryptand), 67.5 (s, [2,2,2]-cryptand), 53.8 (s, [2,2,2]-cryptand), 29.1 (s, −CHMe2), 27.4 (s, −CHMe2), 27.1 (s, −CHMe2), 27.0 (s, −CHMe2), 26.7 (s, −CHMe2), 26.4 (s, −CHC(Me)N−), 26.3 (s, −CHMe2), 25.4 (s, −CHMe2), 25.3 (s, −CHMe2), 24.8 (s, −CHMe2), 24.5 (s, −CHMe2), 23.3 (s, −CHMe2); Elemental Analysis Calcd (%) for C76H116KN6O6Y: C 68.23, H 8.74, N 6.28; found: C 68.54, H 8.81, N 6.45. Synthesis of [nBn4N]+{[η2-N,N-N(2,6-iPr2C6H3)C(Me)CHC( CH2)N(C6H3-iPr2-2,6)]2Y}− (4). A 5 mL THF solution of [Bu4N]+[Cl]− (0.083 g, 0.3 mmol) was added slowly to a THF solution (15 mL) of 2 (0.353 g, 0.3 mmol), and stirred for 48 h at room temperature. Then, the slurry was filtered, and the filtrate was concentrated to ca. 3−4 mL. Yellow crystals of 4 were harvested after the solution was kept for 7 days at −35 °C. Yield: 0.325 g (93%). 1H NMR (400 MHz, THF-d8, RT): δ = 7.03 (m, 2H, Ar), 6.91 (m, 2H, Ar), 6.85 (t, J = 7.5 Hz, 2H, Ar), 6.76 (m, 2H, Ar), 6.69−6.61 (m, 4H, Ar), 5.29 (s, 2H, −CCHC−), 3.97 (m, 2H, −CHMe2), 3.75 (m, 2H, −CHMe2), 3.26 (m, 10H, −CHMe2 and N+(CH2CH2CH2CH3)4), 3.05 (m, 2H, −CHMe2), 2.91 (d, 4JH‑H = 1.7 Hz, 2H, CH2C−), 2.20 (d, 4JH‑H = 2.0 Hz, 2H, CH2C−), 1.74 (s, 6H, −CHC(Me)N−), 1.69 (m, 8H, N+(CH2CH2CH2CH3)4), 1.45 (d, 3 J H‑ H = 6.7 Hz, 6H, −CHMe 2 ), 1.41 (m, 8H, N+(CH2CH2CH2CH3)4), 1.24 (d, 3JH‑H = 6.7 Hz, 6H, −CHMe2), 1.11 (d, 3JH‑H = 6.6 Hz, 6H, −CHMe2), 1.07 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe 2 ), 1.01 (t, 3 J H‑H = 7.4 Hz, 18H, −CHMe 2 and N+(CH2CH2CH2CH3)4), 0.88 (d, 3JH‑H = 6.8 Hz, 6H, −CHMe2), 0.36 (d, 3JH‑H = 6.9 Hz, 6H, −CHMe2), 0.08 (d, 3JH‑H = 6.9 Hz, 6H, −CHMe2). 13C NMR (100 MHz, THF-d8, RT): δ = 155.9 (s, −NC(Me)−), 151.3, 147.9, 147.2, 145.2, 145.1, 144.3, 128.6 (s, Ar), 127.9 (s, Ar), 125.0 (s, Ar), 122.7 (s, Ar), 122.6 (s, Ar), 121.1 (s, Ar), 121.0 (s, Ar), 121.9 (s, Ar), 121.0 (s, Ar), 102.5 (s, −CCHC−), 76.7 (s, CH2C−), 58.3 (t, J = 2.6 Hz, N+(CH2CH2CH2CH3)4), 29.0 (s, −CHMe2), 27.4 (s, −CHMe2), 27.1 (s, −CHMe2), 27.0 (s, −CHMe2), 26.6 (s, −CHMe2), 26.4 (s, −CHC(Me)N−), 26.2 (s, −CHMe2), 25.4 (s, −CHMe2), 25.2 (s, −CHMe2), 24.7 (s, −CHMe2), 24.4 (s, −CHMe2), 23.5 (s, N+(CH2CH2CH2CH3)4), 23.2 (s, −CHMe2), 19.6 (s, N+(CH2CH2CH2CH3)4), 12.9 (s, N+(CH2CH2CH2CH3)4). Elemental Analysis Calcd (%) for C74H116N5Y: C 76.31, H 10.04, N 6.01; found: C 76.62, H 9.87, N 6.17. Synthesis of [K([2.2.2]cryptand)]+[2-S,4-N(Ar),6-(Me)C5H2N(Ar)]−·[2-S,4-N(HAr),6-(Me)C5H2N(Ar)] (5). A cooled THF solution (3 mL) of CS2 (24.2 μL, 0.4 mmol) was added quickly to a THF solution (10 mL) of 3 (0.268 g, 0.2 mmol), and stirred for 72 h at room temperature. Then, the solution was concentrated to ca. 3−4 mL. Yellow crystals of 5 were harvested after the solution was kept for several days at −35 °C. Yield: 0.198 g (74%). 1H NMR (400 MHz, THF-d8, RT) δ = 9.78 (br, 1H, −NH), 7.24−7.16 (m, 2H, Ar), 7.13−7.04 (m, 10H, Ar), F

DOI: 10.1021/acs.organomet.6b00941 Organometallics XXXX, XXX, XXX−XXX

Organometallics

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5.91 (s, 2H, DHP-H), 5.69 (s, 2H, DHP-H), 3.55 (s, 12H, [2,2,2]cryptand), 3.50 (t, 3JH‑H = 4.6 Hz, 12H, [2,2,2]-cryptand), 3.31 (m, 4H, −CHMe2), 2.66 (m, 4H, −CHMe2), 2.51 (t, 3JH‑H = 4.6 Hz, 12H, [2,2,2]-cryptand), 1.73 (s, 3H, −CHC(Me)N−), 1.49 (s, 3H, −CHC(Me)N−), 1.29 (d, 3JH‑H = 6.4 Hz, 12H, −CHMe2), 1.26 (d, 3JH‑H = 6.6 Hz, 6H, −CHMe2), 1.19 (d, 3JH‑H = 6.6 Hz, 6H, −CHMe2), 1.16 (d, 3JH‑H = 6.9 Hz, 12H, −CHMe2), 1.12 (d, 3JH‑H = 6.9 Hz, 12H, −CHMe2). 13C NMR (100 MHz, THF-d8, RT) δ = 179.0 (s, −CS), 154.6 (s, −NC−), 146.3 (s, Ar), 146.0 (s, Ar), 145.8 (s, Ar), 140.4 (s, Ar), 128.3 (s, Ar), 125.1 (s, Ar), 123.9 (s, Ar), 123.7 (s, Ar), 109.4 (s, DHP-C), 108.1 (s, DHP-C), 71.1 (s, [2,2,2]-cryptand), 68.3 (s, [2,2,2]-cryptand), 54.7 (s, [2,2,2]-cryptand), 29.0 (s, −CHMe2), 28.8 (s, −CHMe2), 25.6 (s, −CHMe2), 25.4 (s, −CHMe2), 25.2 (−CHMe2), 25.1 (s, −CHC(Me)N−), 24.5 (s, −CHMe2), 24.1 (s, −CHMe2), 24.0 (s, −CHMe2), 22.1 (s, −CHC(Me)N−). Elemental Analysis Calcd (%) for C78H115KN6O6S2: C 68.92, H 8.70, N 6.32; found: C 68.46, H 8.63, N 6.40. Synthesis of 2-S,4-N(H)Ar,6-(Me)C5H2N(Ar) (6). A cooled THF solution (5 mL) of CS2 (121 μL, 2 mmol) was added quickly to a THF solution (10 mL) of 4 (1.165 g, 1 mmol), and stirred for 48 h at room temperature. Then, the solution was evaporated to dryness under vacuum, and washed with n-hexane (2 × 5 mL). The slurry was filtered, and a yellow solid was obtained. Yellow crystals of 6 were harvested by recrystallization in a mixed solvent of toluene/hexane in 32% isoalted yield (0.295 g). 1H NMR (400 MHz, THF-d8, RT) δ = 7.61 (two broad peaks, 2H, −NH−and −SH), 7.33−7.26 (m, 4H, Ar), 7.25−7.18 (m, 8H, Ar), 7.01 (s, 1H, DHP-H), 6.20 (s, 1H, DHP-H), 6.13 (s, 1H, DHPH), 5.48 (s, 1H, DHP-H), 3.25 (br, m, 4H, −CHMe2), 2.56 (m, 4H, −CHMe2), 1.87 (s, 3H, −CHC(Me)N−), 1.73 (s, 3H, −CH C(Me)N−), 1.29 (d, 3JH‑H = 6.4 Hz, 6H, −CHMe2), 1.25 (d, 3JH‑H = 6.4 Hz, 6H, −CHMe2), 1.19 (d, 3JH‑H = 6.6 Hz, 30H, −CHMe2), 1.14 (d, 3 JH‑H = 6.6 Hz, 6H, −CHMe2). 13C NMR (100 MHz, THF-d8, RT) δ = 183.2(s, −CS), 181.7 (s, −C-S), 153.0 (s, −NC−), 152.1 (s, −HNCCH−), 150.5 (s, Ar), 149.0 (s, Ar), 148.4 (s, Ar), 147.7 (s, Ar), 145.5 (s, Ar), 145.4 (s, Ar), 139.4 (s, Ar), 134.2 (s, Ar), 129.2 (s, Ar), 128.8 (s, Ar), 128.7 (s, Ar), 124.6 (s, Ar), 124.5 (s, Ar), 112.5 (s, DHPC), 110.6 (s, DHP-C), 104.5 (s, DHP-C), 101.8 (s, DHP-C), 29.2 (s, −CHMe2), 29.1 (s, −CHMe2), 29.0 (s, −CHMe2), 25.0 (s, −CHMe2), 24.5 (s, −CHMe2), 24.4 (−CHMe2), 23.9 (s, −CHMe2), 23.7 (s, −CHMe2), 23.5 (s, −CHMe2), 23.4 (s, −CHMe2), 22.3 (s, −CH C(Me)N−). HRMS (ESI, m/z): Calcd for C30H40N2S [M + H]+ 461.2990; Found: 461.2993. X-ray Data Collection, Structure Determination, and Refinement. Suitable single crystals of complexes 1−6 were sealed under argon in Lindemann glass capillaries for X-ray structural analysis. Diffraction data were collected on a Bruker SMART Apex CCD diffractometer using graphite-monochromated MoKα (λ = 0.71073 Å) radiation. During the intensity data collection, no significant decay was observed. The intensities were corrected for Lorentz-polarization effects and empirical absorption with the SADABS program.16 The structures were solved by the direct method using the SHELXL-97 program.17 All non-hydrogen atoms were found from the difference Fourier syntheses. The H atoms were included in calculated positions with isotropic thermal parameters related to those of the supporting carbon atoms, but were not included in the refinement. All calculations were performed using the Bruker Smart program. A summary of the crystallographic data and selected experimental information are given in STables 1 and 2 (see the Supporting Information).

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*E-mail: [email protected] (J.Z.). *E-mail: [email protected] (X.Z.). ORCID

Jie Zhang: 0000-0002-0584-6609 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We are grateful to the National Natural Science Foundation of China, the 973 program (2012CB821600), and the Shanghai Leading Academic Discipline Project (B108) for financial support.

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.6b00941. 1

REFERENCES

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H− C HSQC NMR spectra of new compounds (PDF) Crystallographic data for 1−6 (CIF) G

DOI: 10.1021/acs.organomet.6b00941 Organometallics XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.organomet.6b00941 Organometallics XXXX, XXX, XXX−XXX