Diamondoid Hydrazones and Hydrazides: Sterically Demanding

Article pubs.acs.org/Organometallics

Diamondoid Hydrazones and Hydrazides: Sterically Demanding Ligands for Sn/S Cluster Design Beatrix E. K. Barth,§ Boryslav A. Tkachenko,‡ Jens P. Eußner,§ Peter R. Schreiner,‡ and Stefanie Dehnen*,§ §

Department of Chemistry and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg, 35037 Marburg, Germany ‡ Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, 35392 Giessen, Germany S Supporting Information *

ABSTRACT: A series of new adamantane and diamantane hydrazides was synthesized and coupled with organo-functionalized Sn/S clusters of the general type [R1Sn4S6] (R1 = CMe2CH2COMe) to form diamondoid-decorated Sn/S clusters. The new ligand precursors as well as the resulting hybrid compounds were analyzed by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction, and first insights were gained in the installation of sterically highly demanding and at the same time rigid mono-, di-, and trifunctionalized diamondoid ligands on tetrelchalcogenide cages.

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INTRODUCTION The vast development of organic−inorganic hybrid compounds arises mainly from the inventive use of both inorganic and organic building blocks to create extended structures of diverse dimensionalities with various compositions and topologies.1 The majority of these compounds belong to the research fields of metal−organic frameworks (MOFs)2 and covalent organic frameworks (COFs).3 Another direction of research is covered by the interconnection of inorganic clusters from zero-dimensional up to three-dimensional topologies (0-D, 1-D, 2-D, and 3-D).4 In spite of the multifaceted flexibility of chalcogenido moieties (E2−) and their versatile bridging modes in coordination and cluster chemistry, a homologous extension of the large group of polyoxometalate (POM)-based hybrid materials5 toward hybrid inorganic−organic compounds comprising chalcogenide clusters has been rare so far.6 Purely inorganic chalcogenidometalates have been attracting attention due to (photo)catalytic, photoluminescent, and thermoelectric properties7 or their recently observed outstanding capability of Li ion storage or conductivity.8 The modifications range from discrete clusters to chains and networks, which combine structural properties of zeolites with physical properties of semiconductors.9 However, embedding of chalcogenidometalate clusters into organic ligand shells provides the opportunity to further modify and tune the properties of these compounds.10 Besides affecting solubility and stability, the presence of functional groups at the organic ligands allows for further extensions of the organic shell. Recently, we showed that condensations of keto-functionalized double-decker-like complex [(R1Sn)4S6] (1; R1 = CMe2CH2COMe) with a variety of hydrazine derivatives not only are possible but may come along with transformations of the inorganic cluster core, depending on the steric influence of the organic group.11 This led to a variety of T/E architectures (T = Ge, Sn; E = S, Se, Te) © 2014 American Chemical Society

ranging from dinuclear complexes to hybrid macrocycles or capsules.10a,12 As another extension of our work, we aim at introducing highly rigid ligands to affect the aggregation by introducing steric restrictions. Suitable but at the same time demanding candidates from the synthetic point of view are the diamondoids adamantane and diamantane. Besides its natural abundance and its use in pharmaceuticals,13 adamantane (C10H16) is also a multifaceted building block, due to its rigid and precisely defined geometrical shape, steric demand, and physical properties.14 It serves, for instance, as an anchoring unit for self-assembled monolayers (SAMs), ensuring fixed angles of the adsorbed molecule relative to the metal surface,15 or as tripodal anchoring points for TiO2 nanoparticles in the synthesis of azulene chromophores.16 By now, selective functionalization techniques have been wellestablished for adamantane;13a,17 moreover, selective mono- and difunctionalizations of higher diamondoids (i.e., those with isomers starting with tetramantane) with unequal substituents were published recently.18 Herein, we report on the successful grafting of Sn/S complexes with such diamondoid units upon mono- and polyfunctionalization. Several of the required ligand precursors have been prepared for the first time.

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RESULTS AND DISCUSSION According to our goal to attach diamondoids to Sn/S clusters, we have selected a variety of mono-, di-, and trifunctionalized adamantane and diamantane derivatives (i−vii, Chart 1) with the Received: January 8, 2014 Published: April 2, 2014 1678

dx.doi.org/10.1021/om500014z | Organometallics 2014, 33, 1678−1688

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Chart 1. Survey of the Diamondoid Derivatives Used to Graft Sn/S Clusters in This Report along with Their Respective Precursors: 1-Adamantylmethylhydrazone (i),21a Adamantane-1-carbohydrazide (ii),21b Adamantane-1,3-dicarbodihydrazide (iii)22 and Its Precursor 1,3-Adamantane Dicarboxylic Acid Diethyl Ester (iii′), 2-(1-Carbohydrazideadamantane-3-yl)acetic Acid Hydrazide (iv) and Its Precursor Ethyl 2-(1-Ethoxycarbonyladamantane-3-yl)acetate (iv′), 2,2′-(Adamantane-1,3-diyl)diacetic Acid Dihydrazide (v) and Its Precursor Diethyl 2,2′-(Adamantane-1,3-diyl)diacetate (v′),23 2,2′-(Diamantane-4,9-diyl)diacetic Acid Dihydrazide (vi) and Its Precursor Dimethyl 2,2′-(Diamantane-4,9-diyl)diacetate (vi′),24 2,2′,2″-(Adamantane-1,3,5triyl)triacetic Acid Trihydrazide (vii) and Its Precursors Trimethyl 2,2′,2″-(Adamantane-1,3,5-triyl)triacetate (vii′), 2,2′,2″(Adamantane-1,3,5-triyl)triacetonitrile (vii″), and 1,3,5-Tris(bromomethyl)adamantane (vii″′)a

dihydrazide vi was obtained as a pearlescent, colorless powder in quantitative yield. Monofunctionalized Diamondoid Units at Sn/S Clusters. We performed a condensation reaction of the known Sn/S cluster 1 with monofunctionalized 1-adamantylmethyl ketone hydrazone (i) under mild conditions, which led to the formation of the novel organotin sulfide complex [(R2Sn)4Sn2S10] (2; R2 = CMe2CH2CMeNNCMeAd; Ad = adamantyl, C10H15). The electrospray ionization (ESI) mass spectrum of the reaction mixture that yields compound 2 (Figure S1) exhibits no peak according to the sum formula of 2, [(R2Sn)4Sn2S10]. Similar to our previous observation made for related bispyridyl-decorated complexes,11 compound 2 is thus not retained in solution. Instead, the ESI mass spectrum shows a mass cluster centered at m/z 1305.2998 (100% relative abundance) that fits the empirical formula [(R2Sn)3S4]+, [3]+ .We suggest this cation has the defect-heterocubane structure shown along with the mass spectrum in Figure 2. In contrast to cationic Sn/Se clusters that had been recently obtained as salts [(R1,1′Sn)3Se4][SnCl3] (R1′ = CMe2CH2CNNH2Me),25 the cation does not crystallize as its salt in the present case. Additionally, the 119Sn NMR shows one signal, at −70 ppm, that is in good agreement with a species like [3]+ in solution, as compared with the chemical shifts observed at other [RSn3S4]+ complexes;11,25 accordingly, we suggest that the structure of [3]+

aim to bind them to Sn/S precursor cluster A with complementary functionality. The mono- and difunctionalized diamondoids ii−v and the trifunctionalized adamantane derivative vii were prepared via esterification of the respective commercially available carboxylic acids (see general remarks in the Experimental Section). Diamantane derivative vi as well as compound iv, vii, and its precursors vii′−vii″′ have not been reported to date. We synthesized vii in a four-step sequence from the known adamantane-1,3,5-tricarboxylic acid trimethyl ester19 (see Experimental Section for details). Compound iii was obtained as single crystals in the monoclinic space group Pn (Figure 1 and Figure S14) with two molecules of iii per asymmetric unit. Intermolecular hydrogen bonds exist between the hydrazide groups (O, N, and H atoms). The shorter ones are O1···H31 (O1−N5 = 2.920(9) Å, O1−H31− N5 = 172(9)°) and O4ii···H28 (O4ii−N3 = 2.884(9) Å, O4ii− H28−N3 = 172(9)°, ii = 1+x, y, z), which are connected into a helix along the a-axis. The absolute configuration of this helix cannot be given due to twinning (which requires twin refinement). Weaker interactions exist in the form of a network along the crystallographic (110)-plane. Hydrazination was carried out under reflux in a mixture of hydrazine hydrate (80%) and EtOH (10:2). Oligomeric side products were separated by column chromatography, if necessary (iii−v). Hydrophilicity was observed for iii−v and vii, which were prepared as colorless foams in yields of 73−100%. The 1679


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Figure 1. Asymmetric unit of iii with the shortest hydrogen bonds denoted as light blue, dotted lines (left-hand side). Illustration of the H-bonded helix formed in the crystal structure of iii (right-hand side, adamantane hydrogens are omitted for clarity). Thermal ellipsoids are drawn at the 50% probability level. Selected hydrogen bonds (extract of Table S2): H25···O2i = 2.23 Å (i = 0.5+x, 2−y, 0.5+z), N1−H25−O2i = 155.8°, H26···O3ii = 2.28(2) Å (ii =1+x, y, z), N2−H26−O3ii = 175(4)°, H28···O4ii = 2.027(10) Å, N3−H28−O4ii = 170(4)°, H31···O1 = 2.071(9) Å, N5−H31−O1 = 171(4)°, H34···O3iii = 2.165(9) Å (iii = 0.5+x, 1−y, z−0.5), N7−H34−O3iii = 169(4)°.

Figure 2. Mass peak of [3]+ at m/z = 1305.2998 in the ESI (+) mass spectrum of the reaction solution of 2 (dichloromethane/methanol, 1:1), as measured (top) and simulated (bottom; m/z = 1305.2948) along with the suggested topology of the cation. The overview spectrum is provided in the Supporting Information (Figure S1).

represents a defect-heterocubane.10a,26 A summary of the findings is provided in Scheme 1. Whereas the formation of 2 was fast and allowed for mild conditions, an inverse reaction of the known hydrazonefunctionalized cluster [(R3Sn)4S6] 4 with 1-adamantylmethyl

ketone or 1-adamantanecarboxylic acid ethyl ester did not show any progress, neither under the same mild conditions (rt, CH2Cl2) nor under reflux for several hours. A possible explanation would be that the sterical hindrance at the electrophilic carbon atom of the isohexyl-2-on group at 1 is relatively low and allows for the rapid 1680


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Scheme 1. Formation of 2 by Reaction of 1 with i

Figure 3. Molecular structure of the adamantane-decorated Sn/S cluster 2 (left-hand side) and asymmetric unit of the molecular structure of 2 (righthand side). Hydrogen atoms, solvent molecules, and disordered organic moieties are omitted for clarity. Thermal ellipsoids are drawn at the 50% probability level.

119.7(5)°, S2−Sn2−S4 113.89(12)°). The deviation can be explained by the strain of the Sn−C−C−C−N ring. The Sn−N distances (Sn2−N3 2.354(13) Å and Sn1−N1 2.388(8) Å) are distinctly shorter than in the case of known aminoalkylsubstituted organotin sulfides, ranging from 2.548(4) to 3.158(5) Å.27 This might be due to the electron-rich ketazinfunctionalized ligand that represents a stronger σ-donor. N−C and N−N distances are in good agreement with reported values for (C)(C,H)−Nx−Ny−(C)(C,H) moieties.28 Condensation of 1 with ii yielded the novel, 4-fold adamantane-functionalized complex [(R4Sn)4Sn2S10]·3.5CH2Cl2 (5·3.5CH2Cl2; R4 = CMe2CH2CMeNNHCOAd; Table S1), which crystallized in the triclinic space group P1̅ with two crystallographically independent molecules of [(R3Sn)4Sn2S10] and seven solvent molecules per asymmetric unit. Both molecules (5a, Figure 4, left-hand side, and 5b, Figure 4, righthand side) differ not only by the orientation of the organic ligands but also in details of the inorganic core. Whereas the [Sn6S10] skeleton of 5a exhibits approximate inversion symmetry, the Sn/S core of 5b exhibits a distinct distortion: whereas most of the S−Sn bond lengths within both molecules are fairly regular (2.391(4)−2.775(4) Å in 5a and 2.382(4)−2.833(4) Å in 5b), Sn10−S17 in 5b is much longer (3.419(4) Å). In 5a, all tin atoms are five-coordinate and show distorted trigonal bipyramidal environments, similar to the situation in 2. All ligands at Sn3 and Sn4 are sulfide ligands, with the axial positions occupied by S1 and S6 (Sn3) or S5 and S7 (Sn4). At Sn1, Sn2, Sn5, and Sn6, the axial positions are occupied by N1, N3, N5, and N7, respectively, and by ligands S1 (Sn1, Sn2) or S7 (Sn5, Sn6), respectively, in trans position. For 5b, the overall situation is similar with the essential difference, however, that N13 is trans to S17, while N15 is trans to S18. Apparently, this decreases the donor capacity of S17 toward Sn10 to the extent that the distance of 3.419(4) Å between both atoms is only slightly shorter than the sum of the van der Waals radii (4.00 Å) of these atoms. All tin atoms, Sn1 to Sn12, are approximately trigonal bipyramidally coordinated,

formation of 2. In contrast, fast attack of 1-adamantylmethyl ketone by the terminal hydrazine nitrogen atom at 4 is obviously hampered by the steric influence of the adamantyl ligand. Compound 2 crystallizes in the triclinic space group P1̅ with four solvent molecules (2·4CH2Cl2; Table S1) and exhibits two μ-S-bridged defect-heterocubane [Sn3S4] scaffolds representing a structural motif often found in this chemistry in the presence of sterically encumbered organic moieties (Figure 3).10a The molecular structure of 2 bears an inversion center. Therefore only one-half of the molecule is visible in the asymmetric unit. Due to intramolecular coordination of the azine nitrogen atoms N1 and N3 to the adjacent tin atoms Sn1 and Sn2, respectively, both ligands are situated in a nearly planar fivemembered ring (Sn1−C1−C4−C5−N1 and Sn2−C19−C22− C23−N3, respectively). The configuration of the NC bonds in these unsymmetrical azine groups can be described as E,Etype.21a Furthermore the azine groups are involved in the following dihedral angles of C5−N1−N2−C8 (95.0(1)°) and C23−N3−N4−C26 (95.7(7)°), which are a result of both the sterical hindrance of the ligands and the intramolecular N→Sn coordination and assume an s-gauche conformation of the overall azine group. All tin atoms are in a nearly trigonal bipyramidal coordination environment, however with different ligand environments: Sn3 (and Sn3i; i = −x+1, −y, −z) is surrounded by five sulfur atoms. The formation of 2 from 1 thus includes Sn−C bond cleaving, which is well-known to be possible.20 The axis S1−Sn3−S5i is nearly linear (177.33(9)°), and S3, S4, and S5 form a nearly perfect equatorial triangle (S3−Sn3−S4 115.63(11)°, S3−Sn3− S5 119.22(11)°, S4−Sn3−S5 124.04(11)°). For Sn1 and Sn2, the C,N,S,S,S environment differs more from a perfect trigonal bipyramidal coordination geometry. While the N−Sn−S axes are also close to linearity (S1−Sn1−N1 176.7(3)°, S1−Sn2−N3 177.8(3)°), the equatorial planes show larger deviations (C1−Sn1−S2 120.3(4)°, C1−Sn1−S3 126.1(4)°, S2−Sn1−S3 111.61(12)°; C19−Sn2−S2 123.0(5)°, C19−Sn2−S4 1681


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Figure 4. Molecular structures of the two adamantane-decorated Sn/S clusters 5a (left-hand side) and 5b (right-hand side) in the asymmetric unit of 5. Note that the relative orientation of the two molecules is not shown here, but in Figure S16. Hydrogen atoms and disordered organic moieties are omitted for clarity. Thermal ellipsoids are drawn at the 50% probability level.

resulting dihydrazide vi exhibits a much larger spacer length than v and provokes a quasi-linear attachment. Reactions with vii represent an extension of these first investigations concerning derivatization of Sn/S cages with diamondoid derivatives toward trifunctionalized adamantane moieties. Reaction of 1 with the dihydrazide iii generated a product mixture that could not be separated and that did not crystallize regardless of the solvent or solvent mixture used or the stoichiometric ratio of the reactants (1:4, 1:2, 1:1). However, performing the reaction in a mixture of N,N-dimethylformamide (DMF) and dichloromethane (1:7) enabled the detection of one product by means of ESI mass spectrometry. [(R5Sn)4S6] (7; R5 = (CMe2CH2CMeNNHCO)2-1,3-Ad) was detected as its monoprotonated derivative [7+H]+ (Figure S5), which indicates a derivatization that retains the original cluster shape of 1. With a relative abundance of 2% (Figure S4), the formation of 7 seems to be rather unfavorable. This might be understood in terms of the steric restrictions introduced by the small spacer and the acute angle between the anchor groups, which inhibits the formation of an intramolecular linkage, such as observed for [(R10Sn2)2(μ-S)6] (R10 =(CMe2CH2CMeNNCH)2C6H4)12b and [(R11Sn2)2(μ-S)6] (R11 = (CMe2CH2CMeNNCH)2fC, fC = ferrocenyl).29 Presumably, an intermolecular linkage upon attachment of one of the difunctionalized diamondoids to each of the tin atoms would be favored, however, obviously yielding a mixture of oligomers or even polymers. The structure of 7 can therefore be viewed as one of the possible intermediates with no intermolecular extension. Similar results have been obtained by reaction of 1 with one equivalent of iv, which differs from iii by one additional methylene group. In this case, the mass peak of [(R6Sn)4S6] (8; R 6 = (CMe 2 CH 2 CMeNNHCO)-1,3-Ad-(CH 2 CONHNCMeCH2CMe2)), which was detected as its adduct with Na+, [8+Na]+, is overlain by two further, so far unidentified products with slightly smaller and slightly larger m/z values, respectively (Figure S7, overview spectrum Figure S6). The relative abundance of [8+Na]+ is 14%. The combination of 1 with four equivalents of v resulted in the formation of a colorless reaction solution. Layering of this solution by 1,4-dioxane or m-xylene yielded crystals of [(R7Sn)4Sn2S10]· 2(1,4-dioxane)·4CHCl3 (9·2(1,4-dioxane)·4CHCl3, 9a; R7 = (CMe2CH2CMeNNHCOCH2)2-1,3-Ad) or [(R7Sn)4Sn2S10]·mxylene (9·m-xylene; 9b), respectively.

except for Sn12: here the axial angle N15−Sn12−S18 (169.2(3)°) deviates considerably from the angles found for all others, ranging from 173.3(3)° to 179.6(3)°. The Sn−N distances of 5a and 5b range from 2.317(13) to 2.477(13) Å, similar to those found in the structure of 2, despite the presence of slightly different organic groups. Although both complex molecules in compound 5 exhibit the same cluster motif as in 2, the functionalization with adamantane-1-carbohydrazide produced N-acetylhydrazone units in 5, instead of azine groups in 2, affecting the overall chemical properties of the compound. After 12 h reaction time, the reaction mixture possesses a light yellow color and exhibits a lower crystallization tendency than the azine-functionalized species under the same conditions. Moreover, 5 is much more sensitive to moisture and air. Again, ESI mass spectrometry of the reaction solution of 5 does not produce a mass peak at 2134.9918 m/z for [(R4Sn)4Sn2S10] (Figure S2), while the sum formula of an organo-decorated defect-heterocubane [(R4Sn)3S4]+ ([6]+) was detected with a relative abundance of 100% (Figure S3). We assume that the cluster formation and crystallization processes again follow the same pattern as observed for bispyridyldecorated species11 and for the related compounds 2 and [3]+. Di- and Polyfunctionalized Diamondoid Units at Sn/S Clusters. The next step comprised condensation reactions of double-decker-like cluster 1 with a variety of di- or trifunctionalized adamantane derivatives, involving hydrazide anchors for condensation with 1 to achieve intra- or intermolecular linkages. The chosen reactants (Chart 1) differ in the resulting spacer length in the following manner: focusing on the two quaternary carbon atoms to which the hydrazide or carbohydrazide groups are connected, molecule iii has a C2h-symmetric structure and represents the adamantane derivative within the shown series that possesses the shortest spacer length and, accordingly, the largest steric hindrance. Inclusion of one methylene group leads to an increase of the distance between the hydrazide group and the quaternary carbon atom for one of the anchors, producing the asymmetric molecule iv. The flexibility of this molecule is higher compared to iii at the respective hydrazide-functionalized position. Finally, compound v comprises two acetic acid hydrazide groups, leading to the least rigidity of the difunctionalized adamantane spacer molecules within this series. A related functionalization was realized with diamantane vi; however, due to the larger diamantyl cage, the 1682


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The 119Sn NMR spectrum of the reaction mixture in CDCl3 that yielded 9a or 9b upon layering shows only one signal at −81 ppm. Very obviously, isolated defect-heterocubane-like subunits, such as in [3]+ or [6]+, are not likely to form here due to the mismatch between the involved number of three tin atoms and a ligand that bridges ever two tin atoms. A possible alternative that would explain the observation of only one signal might be the formation of two defect-heterocubane-like cations that are bridged by a third organic ligand; here the 119Sn chemical shifts should be at least very similar. The applicability of this assumption seems to be underlined by the subsequent studies involving further bridging ligands vi and vii (vide inf ra). As expected, the mass spectrum of the reaction solution yielding 9 (Figure S8) does not comprise the mass peak of 9 at 1923 m/z, but only peaks at lower masses below m/z = 1600 (1273.1614 m/z, 1039.0339 m/z, 822.9177 m/z). One of the peaks (m/z = 1273.1614) is close to the sum formula of one protonated half of 9 ([(R7Sn3S4)+H]+, calculated m/z = 1273.1829; Figure S9), in accordance with a defect-heterocubanelike unit that bears one terminal SH group at the “inorganic” tin atom instead of the Sn2S2 ring that bridges two subunits in the crystal. However, we would like to emphasize that this should be considered only a plausible suggestion, since an corresponding species had not been reported or isolated before. Both 9a and 9b crystallize in the monoclinic space group P21/c and possess crystallographic inversion symmetry. The cluster units within both compounds are essentially identical (Figure 5), representing extended Sn/S cages with two intramolecular ligand bridges. The most significant difference between both compounds is thus the arrangement of the clusters and the solvent molecules within the crystal lattice (Figures S17 and S18). As shown in Figure 5, the adamantyl molecules are accommodated near the missing corner of the defect-heterocubane scaffolds. Due to the inversion symmetry of the molecules, the straps are inversely arranged on each side of the cluster, producing an overall S-shape of the organo-functionalized cluster. Hence, a sort of trans orientation is found for the arrangement of the adamantyl groups in relation to the Sn6S10 cluster core, as viewed

on the central Sn2S2 ring (Figure 5, top right); however, the molecules exhibit near-C2h symmetry, with the adamantyl groups being situated on the idealized horizontal mirror plane. The orientation of the ligands is obviously favored by S···H(C) hydrogen bonding interactions (S2···C20, 3.850(1) Å; S3···C22, 3.800(1) Å in 9a; S3···C20, 3.843(8) Å; S4···C25, 3.858(9) Å in 9b). All bond lengths in 9a and 9b are in good agreement with regular bond lengths in the given coordination environments. Again, in the inorganic cores all tin atoms are 5-fold coordinated by heteroatoms with approximately trigonal bipyramidal coordination spheres. The N/S−Sn−S angles of the axialcoordinated atoms range from 175.4(3)° (N3−Sn2B-S2 in 9b) to 179.30(10)° (N1−Sn1−S2 in 9b) for both structures. One exception is the angle S2−Sn3B−S5Bi in 9b, at 168.3(5)°. The small angle can be explained by the disordered Sn3 and S5 atoms of the inorganic core. The Sn−N distances of 9a and 9b range from 2.367(8) Å (Sn2−N3 in 9a) to 2.422(7) Å (Sn1−N1 in 9a) with, again, the exceptional bond lengths of Sn2A−N3 at 2.270(7) Å and of Sn2B−N3 at 2.516(9) Å, justified by the disorder of the involved tin atoms. Previously, we reported on the dependency of the observed Sn/S cage structure on the N···N distance (“spacer lengths”) of the attached ligands.12b The current study clearly shows that this is only one of the crucial parameters. With a spacer length of 6.534(9) Å (N1···N3, 9a) and 6.555(3) Å (N1···N3, 9b), the cluster core would be expected to retain the original doubledecker-type cluster moiety with crosswise linking of the tin atoms, as reported for ligands of this “bite”,12b instead of rearranging into a [Sn6S10] unit, as observed herein. The latter, in turn, has so far been observed only upon reaction of molecules such as 1,1′-(1,5-naphthalenediyl)bishydrazine or para-phenylene bishydrazine, which provoke spacer lengths of more than 0.8 Å, which led to formation of two [Sn6S10] clusters bridged by four organic straps to form a discrete cavitand molecule.12b,30 The clusters observed in 9a and 9b thus represent the first [Sn6S10] cage with intramolecular ligand bridges. We ascribe this finding to the tetrahedral angle and the bulkiness of the adamantane cage, thus extending the previously detected impact

Figure 5. Molecular structure of the Sn/S cluster 9a, as an example of structurally related compounds 9a and 9b comprising an intramolecular adamantyl bridge; three different orientations are shown, each spotlighting another part of the unique topology. Hydrogen atoms and disordered organic moieties are omitted for clarity. Thermal ellipsoids are drawn at the 50% probability level. 1683


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Scheme 2. Formation (nonstoichiometric) of the Dication [10]2+ by Reaction of 1 with Diamantane Dihydrazide via

a

Further byproducts, such as SnS and H2, are those observed and discussed for related reactions.11

Scheme 3. Formation (nonstoichiometric) of the Cation [11]+ by Reaction of 1 with 3-Fold Hydrazide-Functionalized Adamantane Derivative viia

a

Further byproducts, such as SnS and H2, are those observed and discussed for related reactions.11

hence we suggest the molecular structure shown in Scheme 2 to be realized in [10]2+. Employment of the first 3-fold hydrazide-functionalized adamantane derivative vii increases the possibility of intermolecular reactions between the clusters. However, similar results were obtained by reaction of 1 with 3-fold-functionalized adamantane vii (3:8). Again, ESI mass spectrometry was the only tool to monitor the results of the reaction. An ESI mass spectrum recorded from the reaction solution in methanol/ dichloromethane (1:1) indicated the presence of the cluster cation [R9Sn3S4]+ ([11]+, R9 = (CMe2CH2CMeNNHCOCH2)31,3,5-Ad) in 15% relative abundance (Figures S12 and S13). Scheme 3 presents a plausible formation reaction and suggests the molecular structure of the cation according to its composition.

of the ligands on the Sn/S skeleton of the organic functionalized cluster. The isolation of compounds 9a and 9b confirms the assumption of additional methylene groups at the ligands, which reduce the steric rigidity that obviously supports product formation. Having gained considerable experience with the reactivity and properties of adamantane derivatives, we have been eager to determine how the sterically more demanding diamantane derivative vi would behave. Reactions with 1 did not yield a pure product, due to the presence of inseparable product mixtures and solubility problems, similar to that described above for the reactions with iii and iv. However, a peak at 1226.64 m/z in the ESI mass spectrum of the reaction mixture in dichloromethane/ DMF (1:1), with a relative abundance of 53%, matches very well the molecular formula of the dication [R8Sn6S8]2+ ([10]2+; R8 = (CMe2CH2CMeNNHCOCH2)2-4,9-diam; Figures S9 and S10), the structure of which might be analogous to the rugby-balllike capsule [R113Sn6S8]2+ (R11 = (CMe2CH2CMeNNH)2-1,5naphthalene) that we have reported previously.12a In the quoted compound, the dication consists of two [Sn3S4] defect-heterocubanes that are linked by three organic straps;

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CONCLUSION To summarize the results, we optimized synthesis routes to previously known (adamantane-1,3-dicarbodihydrazide, 2-(1carbohydrazideadamantane-3-yl)acetic acid hydrazide) and 1684


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m/z calcd 317.1723 [M + Na]+, found 317.1721. Anal. Calcd for C17H26O4: C, 69.36; H, 8.90, Found: C, 69.11; H, 8.92. Synthesis of Diethyl 2,2′-(Adamantane-1,3-diyl)diacetate (v′) (ref 23). NMR (ppm, CDCl3): 1H, 4.1 (q, 4H, J = 7.14, COOCH2Me), 2.1 (s, 4H, CH2COOEt), 2.0−2.1 (m, 2H, Ad), 1.4−1.6 (m, 12H, Ad), 1.2 (t, 6H, J = 7.13 COOCH2Me); 13C, 171.8 (CO), 60.1 (CH2), 48.7 (CH2), 47.5 (CH2), 41.7 (CH2), 36.0 (CH), 33.6 (CH), 29.1 (CH2), 14.6 (CH3). IR (cm−1): 2980 (w), 2901 (m), 2849 (w), 1728 (s), 1447 (m), 1370 (m), 1324 (m), 1248 (m), 1178 (w), 1134 (s), 1031 (s), 732 (s). HRMS: m/z calcd 331.1880 [M + Na]+, found 331.1880. Anal. Calcd for C18H28O4: C, 70.10; H, 9.15, Found: C, 70.12; H, 9.06. Synthesis of Dimethyl 2,2′-(Diamantan-4,9-diyl)diacetate (vi′). vi′ was prepared and analyzed according to reported methods.24 Synthesis of 1,3,5-Tri(bromomethyl)adamantane (vii″′). A solution of 2,2′,2″-(adamantane-1,3,5-triyl)triacetic acid trimethyl ester19 (5.24 g, 16.87 mmol) in Et2O (100 mL) was added dropwise to a suspension of well-triturated LiAlH4 (3.85 g, 101.23 mmol) in dry Et2O (400 mL). The resulting mixture was refluxed overnight. The reaction mixture was cooled to 0 °C (ice bath), and consecutively water (4 mL), 10% aqueous NaOH (4 mL), and again water (12 mL) were added dropwise, followed by stirring of the reaction mixture at rt for 30 min. A colorless solid obtained by evaporation of the colorless suspension in vacuo was flooded with aqueous HBr (48%, 250 mL), and the resulting mixture was refluxed (165 °C in an oil bath) for 24 h. The mixture was cooled to room temperature and diluted with water (250 mL), and the crude product was extracted with CHCl3 (3 × 50 mL). The combined extracts were washed with water and brine and were dried over Na2SO4. Solvent removal yielded 5.1 g of crude product, which was purified on a silica gel column (2% Et2O in pentane), providing pure 1,3,5tri(bromomethyl)adamantane (vii″′) (3.96 g, 57%). Colorless solid. Mp = 91−93 °C (methanol). NMR (ppm, CDCl3): 1H, 3.2 (s, 6H, CCH2Br), 2.2 (sep, 1H, CH), 1.4−1.5 (m, 6H, CCH2CH), 1.3 (s, 6H, CCH2C); 13C, 46.27 (CH2), 43.28 (CH2), 39.38 (CH2), 35.44 (C), 28.97 (CH). MS: m/z (%) = 53 (8), 79 (13), 91 (21), 105 (23), 117 (7), 159 (8), 185 (10), 239/241 (9), 319/323 (51), 321 (100), 333/337 (5), 335 (10), 414/416 (0.5). IR (KBr, cm−1): 2938 (s), 2904 (s), 2844 (s), 1427 (m), 1343 (m), 1253 (s), 1154 (m), 1100 (m), 976 (m), 880 (m), 829 (m), 694 (m), 642 (m), 621 (s), 566 (m). HRMS: m/z calcd for C13H19Br3 411.9037, found 411.8998. Anal. Calcd for C13H19Br3: C, 37.62; H, 4.61. Found: C, 37.81; H, 4.63. Synthesis of 2,2′,2″-(Adamantane-1,3,5-triyl)triacetonitrile (vii″). Tribromide vii″′ (3.00 g, 7.23 mmol) and n-Bu4NF·3H2O (11.40 g, 36.15 mmol) were dissolved in CH3CN (235 mL). Upon addition of TMSCN (3.59 g, 4.52 mL, 36.15 mmol), the reaction mixture was refluxed for 6 d. Upon cooling to room temperature, the reaction mixture was diluted with water (235 mL) and the crude product was extracted with CHCl3 (4 × 60 mL). The combined organic extracts were washed with water and brine and were dried over Na2SO4. Solvent removal provided a considerable amount of dark residue, which was loaded on a silica gel column. Traces of unreacted starting material along with other impurities were washed with pentane; changing the eluent to Et2O produced pure 2,2′,2″-(adamantane-1,3,5-triyl)triacetonitrile vii″ (1.68 g, 92%). Colorless solid. Mp = 159−161 °C (benzene). NMR (ppm, CDCl3): 1H, 2.3 (sep, 1H, CH), 2.2 (s, 6H, CCH2CN), 1.5−1.6 (m, 6H, CCH2CH), 1.5 (ABq, J = 23.9 Hz, 12.0 Hz, 6H, CCH2C); 13C, 116.89 (CN), 44.76 (CH2), 39.50 (CH2), 33.71 (C), 31.07 (CH2), 28.46 (CH). MS: m/z (%) = 91 (6), 105 (4), 117 (3), 130 (10), 145 (2), 157 (4), 172 (11), 186 (4), 213 (100), 253 (0.23). IR (KBr, cm−1): 3425 (b), 2925 (s), 2855 (s), 2245 (s), 1449 (s), 1422 (s), 1367 (m), 1356 (m). HRMS: m/z calcd for C16H19N3 253.1579, found 253.1576. Anal. Calcd for C16H19N3: C, 75.85; H, 7.56; N, 16.59. Found: C, 75.71; H, 7.64; N, 16.75. Synthesis of Trimethyl 2,2′,2″-(Adamantane-1,3,5-triyl)triacetate (vii′). Trinitrile vii″ (1.30 g, 5.12 mmol) and KOH (9.48 g, 169.06 mmol) were suspended in diethyleneglycol (40 mL), and the resulting mixture was stirred (170 °C in an oil bath) for 24 h. Upon cooling to room temperature, the reaction mixture was diluted with water (to 400 mL), nonacidic products were extracted with CHCl3 (3 × 30 mL), the aqueous layer was acidified to pH = 1 (conc HCl) and saturated with NaCl, and the crude triacid was extracted with EtOAc (7 × 100 mL).

developed novel synthesis routes to hydrazide adamantane derivatives, namely, 2,2′-(adamantane-1,3-diyl)diacetic acid dihydrazide, 2,2′-(diamantane-4,9-diyl)diacetic acid dihydrazide, and 2,2′,2″-(adamantane-1,3,5-triyl)triacetic acid trihydrazide. All of them were successfully linked to the organic ligand sphere of Sn/S clusters, which was confirmed by means of mass spectrometry and/or X-ray diffraction and 119Sn, 1H, and 13C NMR spectroscopy. We present novel organo-functionalized Sn/S complexes [(R 2 Sn) 4 Sn 2 S 10 ] (2), [(R 2 Sn) 3 S 4 ] + ([3] + ), [(R4Sn)4Sn2S10] (5), [(R4Sn)3S4]+ ([6]+), [(R5Sn2)2(μ-S)6]+ ([7+H]+), [(R6Sn2)2(μ-S)6]+ ([8]+), [(R7Sn)4Sn2S10] (9), [(R8Sn2)3S8]2+ ([10]2+), and [R9Sn3S4]+ ([11]+) (R2 = CMe2CH2C(Me)NNCMeAd, R4 = CMe2CH2CMeNNHCOAd, R 5 = (CMe 2 CH 2 CMeNNHCO) 2 -1,3-Ad, R 6 = (CMe 2 CH2CMeNNHCO)-1,3-Ad-(CH2CONHNCMeCH2CMe2), R 7 = (CMe 2 CH 2 CMeNNHCOCH 2 ) 2 -1,3-Ad, R 8 = (CMe2CH2CMeNNHCOCH2)2-4,9-Diam, R9 = (CMe2CH2CMeNNHCOCH2)3-1,3,5-Ad), which either were received as single crystals (neutral compounds) or detected by means of electrospray ionization mass spectrometry (cations). First insights were gained into the impact of sterically demanding diamondoid ligands on the composition and shape of organofunctionalized Sn/S clusters.

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EXPERIMENTAL SECTION

Syntheses. General Procedures. All manipulations were performed under an argon atmosphere, unless otherwise noted. All solvents were dried and freshly distilled prior to use. The syntheses of the known ligand reactants i21a and ii21b and the precursors v′23,31 and vi′24,31 were carried out according or similar to literature procedures. Compounds iii,22 v (CAS 329699-84-5), and iv′ (CAS 201480-27-5) have been mentioned in a patent or are commercially available, however, without provision of synthesis details. Compounds iv, vi, and vii, as well as the precursor vii′ and further precursors to vii′ (see below), are new compounds. 1-Adamantylmethyl ketone (>98.0%) and 1-adamantanecarboxylic acid ethyl ester (>98.0%) were purchased from TCI; 3-(carboxymethyl)adamantane-1-carboxylic acid (97%), dimethyl adamantane-1,3-dicarboxylate (98%) (iii′), and 2,2′-(adamantane-1,3diyl)diacetic acid (97%) were purchased from Sigma-Aldrich; sulfuric acid (95−97%) was purchased from Fluka; N2H4·H2O (80% in water) was purchased from Merck and used as received. Silica gel 60 from Macherey-Nagel was used with 0.063−0.2 mm/70−230 mesh ASTM. NMR signals have been assigned with the help of NMR APT and COSY measurements. Synthesis of 1-Adamantylmethyl Ketone Hydrazone (i). i was prepared and analyzed according to reported methods.21a Synthesis of 1-Adamantane Carbohydrazide (ii). ii was prepared and analyzed according to reported methods.21b General Procedure for the Synthesis of Adamantyl Diesters iv′ and v′. On the basis of reported procedures31 dicarboxylic acid (12.0 mmol) was dissolved in 50 mL of ethanol, concentrated H2SO4 (95−97%, 1 mL) was added, and the mixture was refluxed for 5 h. After cooling, the solution was reduced to 50 mL and diluted with ethylacetate (100 mL). The solution was washed two times with saturated aqueous NaHCO3 solution (2 × 50 mL), dried over Na2SO4, and filtered through a pad of Celite, and the filtrate was concentrated in vacuo. All products were obtained in quantitative yield as pure colorless oils and were used without further purification. Synthesis of Ethyl 2-(1-Ethoxycarbonyladamantane-3-yl)acetate (iv′). NMR (ppm, CDCl3): 1H, 4.0−4.1 (m, 4H, COOCH2Me), 2.1 (s, 2H, CH2COOEt), 2.0−2.1 (m, 2H, Ad), 1.5−1.9 (m, 12H, Ad), 1.2−1.3 (m, 6H, COOCH2Me); 13C, 177.4 (CO), 171.6 (CO), 60.4 (CH2), 60.2 (CH2), 48.6 (CH2), 43.7 (CH2), 41.6 (CH), 41.5 (CH2), 38.3 (CH2), 35.9 (CH), 33.2 (CH), 28.6 (CH2), 14.6 (CH3), 14.4 (CH3). IR (cm−1): 2979 (w), 2907 (m), 2855 (w), 1724 (s), 1450 (m), 1372 (w), 1330 (w), 1232 (s), 1164 (w), 1133 (s), 1104 (w), 1037 (s). HRMS: 1685


Organometallics

Article

General Remark on the Cluster Compositions. For clarity, the functional organic ligands at the decorated Sn/S clusters have been abbreviated in the following as R2 = CMe2CH2CMeNNCMeAd, R3 = CMe2CH2CMeNNH2, R4 = CMe2CH2C(Me)N NHCOAd, R5 = (CMe2CH2CMeNNHCO)2-1,3-Ad, R6 = (CMe2CH2CMeNNHCO)-1,3-Ad-(CH 2 CONHNCMeCH 2 CMe 2 ), R 7 = (CMe 2 CH 2 CMeNNHCOCH2)2-1,3-Ad, R8 = (CMe2CH2CMeNNHCOCH2)24,9-diam, and R9 = (CMe2CH2CMeNNHCOCH2)3-1,3,5-Ad. Synthesis of [(R2Sn)4Sn2S10] (2) and Detection of [(R2Sn)3S4]+ ([3]+). 1 (0.046 mmol, 1 equiv) and 1-adamantylmethyl ketone hydrazone (i, 0.188 mmol, 4 equiv) were dissolved in CH2Cl2 (2 mL) and MeOH (2 mL). After stirring for 12 h the colorless precipitate was filtered off the beige/light yellow solution and redissolved in THF. Layering the colorless solution with n-hexane resulted in crystals of 2 (yield: 65%). NMR (ppm, CDCl3): 1H, 2.7 (s, 8H, CH2CMe), 2.0 (br, 12H, AdCMe), 1.6−1.9 (m, 72H, Ad and CH2CMe), 1.4 (s, 24H, CMe2); 13C, 172.2 (CMe2CH2CN), 162.5 (AdCN), 50.3 (CMe2C), 41.2 (CSn), 39.9 (Ad-C), 39.7 (Ad-CH2 ), 36.9 (Ad-CH2), 28.4 (Ad-CH), 26.4 (CH2CMe), 19.3 (CMe2), 14.3 (AdCMe); 119Sn, −70. HRMS of [3]+ in solution (C54H87N6S4Sn3): m/z calcd 1305.2948 [M + H]+, found 1305.2998. Synthesis of [(R4Sn)4Sn2S10] (5) and [(R4Sn)3S4]+ ([6]+). 1 (0.047 mmol, 1 equiv) and adamantane-1-carbohydrazide (ii, 0.188 mmol, 4 equiv) were dissolved in CH2Cl2 (3 mL) and DMF (1 mL). After stirring for 12 h the solvents were removed in vacuo, and the product was redissolved in CHCl3 and filtered. Layering the colorless solution with n-hexane resulted in crystals of 5 (yield: 6%). NMR (ppm, CDCl3): 1H, 2.7 (s, 8H, Me2CCH2), 1.8−2.0 (m, 36H, Ad), 1.7−1.8 (m, 32H, Ad and CH2CMe), 1.4 (s, 24H, CMe2); 13C, 174.1 (AdCO), 162.6 (MeCN), 60.1 (NCOC), 51.1 (CH2CMe), 41.2 (CSn), 39.9 (Ad-CH), 39.2 (CSn), 28.2 (Ad-CH2), 28.1 (Ad-CH2), 26.0 (Me), 21.7 (CMe2); 119Sn, −82 ppm. HRMS of [6]+ (C51H81N6O3S4Sn3): m/z calcd 1309.2321 [M + H]+, found 1309.2345. Reactions Leading to the Generation of [(R5Sn2)2(μ-S)6]+ ([7+H]+). 1 (0.045 mmol, 1 equiv) and iii (0.180 mmol, 4 equiv) were dissolved in CH2Cl2 (7 mL) and DMF (1 mL). After stirring for 48 h the solution turned light yellow. Further attempts to isolate the product in crystalline form failed. HRMS of [7+H]+ (C48H76N8O4S6Sn4): m/z calcd 1519.0301 [M + H]+, found 1519.0321. Reactions Leading to the Generation of [(R 6 Sn 2 ) 2 (μ-S) 6 ] + ([8+Na]+). 1 (0.029 mmol, 1 equiv) and iv (0.120 mmol, 4 equiv) were dissolved in CH2Cl2 (4.5 mL) and DMF (1.5 mL). The light yellow solution was stirred for 18 h. Further attempts to isolate the product in crystalline form failed. HRMS of [8+Na]+ (C50H81N8O4S6Sn4Na): m/z calcd 1548.0693 [M + Na]+, found 1548.0645. Synthesis of [(R7Sn)4Sn2S10] (9). 1 (0.029 mmol, 1 equiv) and v (0.118 mmol, 4 equiv) were dissolved in CH2Cl2 (4.5 mL) and DMF (1.5 mL). After stirring for 12 h the solvents of the light yellow solution were removed in vacuo, and the product was redissolved in CHCl3 and filtered. Layering the slightly yellow solution with p-dioxane (9a) or m-xylol (9b) resulted in colorless crystals and a brown powder (yield: 9−12%). NMR (ppm, CDCl3): 1H, 2.7 (s, 4H, Me2CCH2), 1.9−2.3 (m, 6H, Ad and CH2CO), 1.5−1.7 (m, 18H, Ad and CH2CMe), 1.4 (s, 12H, CMe2); 13C, 175.3 (AdCO), 166.9 (MeCN), 48.5 (CH2CMe), 44.8 (AdC), 41.7 (Ad-CH2), 40.0 (CSn), 35.8 (Ad-CH), 28.9 (Ad-CH2), 25.4 (Me), 21.4 (CMe2); 119Sn, −81 ppm. Reactions Leading to the Generation of [(R8Sn2)3S8]2+ ([10]2+). 1 (0.0047 mmol, 1 equiv) and vi (0.018 mmol, 4 equiv) were dissolved in CH2Cl2 (2 mL) and DMF (2 mL). The reaction was stirred for 18 h. Further attempts to isolate the product in crystalline form failed. HRMS of [10]2+ (C90H139N12O6S8Sn6): m/z calcd 1226.1426 [M]2+, found 1226.1423. Reactions Leading to the Generation of [R9Sn3S4]+ ([11]+). 1 (0.037 mmol, 1 equiv) was dissolved in CH2Cl2 (5 mL), and vi (0.147 mmol, 4 equiv) in DMF (5 mL) was added dropwise to the cooled solution (0 °C). Stirring was continued, the solution was slowly warmed to rt, and after two days a light brown and colorless precipitate appeared and was filtered off. Further attempts to isolate the product in crystalline form failed. HRMS of [11]+ (C34H55N6O3S4Sn3): m/z calcd 1079.0281 [M]+, found 1079.0291.

The combined organic extracts were washed with a small amount of water and brine and were dried over Na2SO4. Solvent removal yielded the crude triacid, which was suspended in CH3OH (50 mL). Concentrated H2SO4 (5 drops) was added, and the resulting mixture was refluxed for 20 h. Water (10 mL) was added to the cooled reaction mixture, and methanol was removed in vacuo. The aqueous layer was extracted with CHCl3 (3 × 15 mL), and organic extracts were combined, washed with water and brine, and dried over Na2SO4. Solvent removal provided an oily residue (1.58 g), which was purified on a silica gel column (20% Et2O in pentane), resulting in pure trimethyl 2,2′,2″(adamantane-1,3,5-triyl)triacetate vii′ (1.42 g, 79%). Colorless oil. NMR (ppm, CDCl3): 1H, 3.6 (m, 9H, CH3), 2.1 (m, 6H, CCH2COO), 2.09−2.13 (m, 1H, CH), 1.5 (m, 6H, CCH2CH), 1.4 (ABq, J = 28.5 Hz, 12.2 Hz, 6H, CCH2C); 13C, 171.95 (COO), 51.27 (CH3), 47.77 (CH2), 46.29 (CH2), 40.53 (CH2), 34.05 (C), 29.09 (CH). MS: m/z (%) = 59 (10), 91 (14), 105 (19), 145 (23), 159 (17), 163 (37), 205 (21), 219 (30), 247 (100), 279 (47), 292 (11), 321 (6), 352 (5). IR (cm−1): 2995 (m), 2950 (s), 2904 (s), 2849 (s), 1734 (s), 1438 (s), 1330 (s), 1249 (s), 1159 (s), 1060 (m), 1010 (m). HRMS: m/z calcd for C19H28O6 352.1886, found 352.1865. Anal. Calcd for C19H28O6: C, 64.75; H, 8.01. Found: C, 64.46; H, 7.97. General Procedure for the Synthesis of Adamantylcarbohydrazides and -hydrazones iii−vii. Adamantyl ester (1.6 mmol of iii′, iv′, v′, vi′, or vii′, respectively) was suspended in hydrazine hydrate (80%, 120 mL), and ethanol (25 mL) was added. The reaction was refluxed for 6 h, then cooled to room temperature and stirred for an additional 8 h. Either the solution was filtered (vi), or the solvent was removed under reduced pressure (iii−v and vii; bath temp 80 °C). Purification by column chromatography was necessary for v−vii due to formation of the corresponding dimeric products. Column chromatography with silica gel led to decomposition of the product, which was much stronger by using alumina (basic or neutral). Synthesis of Adamantane-1,3-dicarbodihydrazide (iii). Purification by column chromatography with CH2Cl2 → CH2Cl2/EtOH led to iii as a colorless hygroscopic foam (yield: 73%). NMR (ppm, DMSO-d6): 1H, 8.7 (br, 2H, NH), 4.2 (br, 4H, NH2), 2.0−2.1 (m, 2H, Ad), 1.6−1.8 (m, 12H, Ad); 13C, 175.8 (CO), 40.5 (C), 39.5 (CH), 37.8 (CH2), 35.2 (CH), 27.7 (CH2). HRMS: m/z calcd 253.1659 [M + H]+, found 253.1660. Synthesis of 2-(1-Carbohydrazideadamantane-3-yl)acetic Acid Hydrazide (iv). The substance was filtered through a short pad of silica (CH2Cl2 → CH2Cl2/EtOH); the last fractions contained iv as a colorless hygroscopic foam (yield: 63%). NMR (ppm, MeOD-d4): 1H, 2.1−2.2 (m, 2H, CH2CO), 1.6−2.0 (m, 14H, Ad); 13C, 179.3 (CO), 172.6 (CO), 44.8 (C), 42.7 (CH2), 39.7 (C), 39.4 (CH2), 36.9 (CH2), 34.3 (CH2), 30.2 (CH), 30.1 (CH). HRMS: m/z calcd 289.1635 [M + Na]+, found 289.1632. Synthesis of 2,2′-(Adamantane-1,3-diyl)diacetic Acid Dihydrazide (v). The substance was filtered through a short pad of silica (CH2Cl2 → CH2Cl2/EtOH → EtOH); the last fractions contained v as a colorless hygroscopic foam (yield: 83%). NMR (ppm, CDCl3): 1H, 7.6 (br, 2H, NH), 4.6 (br, 4H, NH2), 1.8−2.1 (m, 4H, CH2CO), 1.4−1.6 (m, 14H, Ad); 13C, 175.3 (CO), 48.9 (CH2), 47.2 (CH2), 42.0 (CH2), 36.0 (CH), 33.7 (C), 29.0 (CH2). HRMS: m/z calcd 281.1972 [M + H]+, found 281.1972. Synthesis of 2,2′-(Diamantane-4,9-diyl)diacetic Acid Dihydrazide (vi). The raw product was filtered off the reaction mixture and washed with demineralized water. A colorless pearlescent solid was obtained quantitatively. NMR (ppm, MeOD-d4): 1H, 1.9−2.0 (m, 4H, CH2CO), 1.5−1.8 (m, Diam, 18H); 13C, 173.1 (CO), 48.7 (CH2CO), 44.0 (CH2), 38.9 (CH), 31.9 (C(CH2)4). HRMS: calcd 333.2285 [M + H]+, found 333.2282. Synthesis of 2,2′,2″-(Adamantane-1,3,5-triyl)triacetic Acid Trihydrazide (vii). After removal of the hydrazine solution, vii was obtained quantitatively as a highly hygroscopic colorless foam. NMR (ppm, MeOD-d4): 1H, 2.0−2.1 (m, 1H, Ad), 1.9 (s, 6H, CH2CO), 1.3−1.6 (m, 12H, Ad); 13C, 172.6 (CO), 48.9 (CH2), 48.0 (CH2), 42.1 (CH2), 35.4 (C), 30.9 (CH). HRMS: m/z calcd 375.2115 [M + Na]+, found 375.2113. 1686


Organometallics

Article

Single-Crystal X-ray Crystallography. General. Data collections for the X-ray structure analyses were performed at T = 100 K, using Mo Kα radiation (graphite monochromator, λ = 0.71073 Å) and imaging plate detector systems by Stoe, IPDS2/2T, and by Bruker, D8 Quest. All structures were solved by direct methods with SHELXS97 and refined by full-matrix least-squares refinement against F2 in SHELXL97 (Sheldrick, 1997)32 or SHELXL-2013 (Sheldrick, 2013).33 Where possible, H atoms were inserted assuming idealized geometry and refined riding on their parent atoms with Ueq = nUeq (parent atom), where n = 1.2 for H atoms of methylene groups and n = 1.5 for H atoms of methyl groups. H atoms of N−H groups were found in iii, 9a, and 9b on the difference Fourier map with n = 1.5. Crystallization of diamondoid-decorated Sn/S clusters was rather challenging. All obtained single crystals were of low quality. Table S1 summarizes crystallographic and refinement details. Selected structural parameters within the crystal structures of iii, 3·4CH2Cl2, 5·3.5CH2Cl2, 9a (9·2(1,4dioxane)·4CHCl3), or 9b (9·2m-xylol) are given in Tables S2 and S3 (see Supporting Information). These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam. ac.uk/data_request/cif. Further details on the refinement of the title compounds are provided in the Supporting Information. Spectroscopy and Spectrometry. Nuclear Magnetic Resonance Spectroscopy. 1H NMR (400 MHz), 13C NMR (100 MHz), and 119Sn NMR (186 MHz) measurements were carried out using a Bruker DRX spectrometer at 25 °C. Me4Sn was used as internal standard for 119Sn NMR measurements. The chemical shifts were quoted in parts per million relative to the residual protons of deuterated solvents. Infrared Spectroscopy. IR spectra were recorded on a Bruker Tensor 37. Electrospray Ionization Mass Spectrometry. ESI-MS measurements were performed on a Thermo Fischer Scientific Finnigan LTQ-FT by using solvent as the carrier gas.

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ASSOCIATED CONTENT

S Supporting Information *

Further details on electrospray ionization mass spectrometry, single-crystal X-ray crystallography, and NMR spectra. This material is available free of charge via the Internet at http:// pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Web: http://www. uni-marburg.de/fb15/ag-dehnen. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the Research Training Group GRK1782 and by LOEWE “SynChemBio” (collaboration between the groups of S.D. and P.R.S.). We thank N.-J. Kneusels for his help with some of the syntheses.

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