Distorted <i>commo</i>-Cobaltacarboranes Based on the 5,6-Dicarba-<i>nido</i>-decaborane(12): The First Bimetal Cobalt–Copper Zwitterion-Containing Cluster with Four (B–H)₄···Cu Bonds Not Showing Fluxional Behavior in Solution

Treatment of a recently reported complex [Ph₄P]­[<i>closo,nido-</i>CoH­(2,4-C₂B₈H₁₀)­(7,8-C₂B₈H₁₁)] (<b>1</b>) either by H₂O₂ in acetone or NaH in THF leads to the loss of both the bridging and terminal hydrides yielding the diamagnetic salt of an anionic <i>commo</i>-cobaltacarborane [Ph₄P]­[Co­(2,4-<i>isonido</i>-C₂B₈H₁₀)₂] (<b>2</b>) with the {CoC₂B₈}-cluster units adopting a distorted skeletal geometry of the <i>isonido</i>-type. The anionic <i>commo</i> complex <b>2</b> reacts with in situ generated cationic [CuPPh₃]⁺ species to give stable copper–cobalt zwitterion [Ph₃PCu]­[Co­(2,4-<i>isonido</i>-C₂B₈H₁₀)₂] (<b>3</b>) with four two-electron, three-center (B–H)₄···Cu bonds, and exhibits no fluxional behavior in solution. Complex <b>3</b>, at the same time, in CH₂Cl₂ in the presence of 2-fold excess of PPh₃ readily converts to a new anionic species [(Ph₃P)₃Cu]­[Co­(2,4-<i>isonido</i>-C₂B₈H₁₀)₂] (<b>4</b>) which retains initial <i>isonido</i> geometry. All newly obtained diamagnetic <i>commo</i> complexes were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of complexes <b>2</b> and <b>3</b>

Facile and Reversible 1,3-Dipolar Cycloaddition of Aryl Ketonitrones to Platinum(II)-Bound Nitriles: Synthetic, Structural, and Theoretical Studies

The reaction between <i>trans</i>-[PtCl₂(NCR)₂] (R = Et <b>1</b>, NMe₂ <b>2</b>, NEt₂ <b>3</b>, NC₅H₁₀ <b>4</b>) and the acyclic triaryl ketonitrones Ph₂CN­(O)­C₆H₄R′<i>-p</i> (R′ = H <b>5</b>, Me <b>6</b>, Cl <b>7</b>, OMe <b>8</b>) proceeds as a facile and consecutive two-step intermolecular cycloaddition to give the mono-cycloaddition products <i>trans</i>-[PtCl₂(NCR)­{N^<i>a</i>C­(R)­ON­(C₆H₄R<i>′-p</i>)­C^<i>b</i>Ph₂}]^{(<i>a</i>−<i>b</i>)} (R/R′ = Et/H <b>9</b>, Et/Me <b>10</b>, Et/Cl <b>11</b>, Et/OMe <b>12</b>, NMe₂/H <b>13</b>, NMe₂/Me <b>14</b>, NMe₂/Cl <b>15</b>, NMe₂/OMe <b>16</b>, NEt₂/H <b>17</b>, NEt₂/Me <b>18</b>, NEt₂/Cl <b>19</b>, NEt₂/OMe <b>20</b>, NC₅H₁₀/H <b>21</b>, NC₅H₁₀/Me <b>22</b>, NC₅H₁₀/Cl <b>23</b>, NC₅H₁₀/OMe <b>24</b>) and then the bis-2,3-dihydro-1,2,4-oxadiazole complexes <i>trans</i>-[PtCl₂{N^<i>a</i>C­(R)­ON­(C₆H₄R′<i>-p</i>)­C^<i>b</i>Ph₂}₂]^{(<i>a</i>−<i>b</i>)} (R/R′ = Et/H <b>25</b>, Et/Me <b>26</b>, Et/Cl <b>27</b>, Et/OMe <b>28</b>, NMe₂/H <b>29</b>, NMe₂/Me <b>30</b>, NMe₂/Cl <b>31</b>, NMe₂/OMe <b>32</b>, NEt₂/H <b>33</b>, NEt₂/Me <b>34</b>, NEt₂/Cl <b>35</b>, NEt₂/OMe <b>36</b>, NC₅H₁₀/H <b>37</b>, NC₅H₁₀/Me <b>38</b>, NC₅H₁₀/Cl <b>39</b>, NC₅H₁₀/OMe <b>40</b>). The ketonitrones Ph₂CN­(O)­C₆H₄R′<i>-p</i> were found to be unexpectedly much more reactive toward the platinum­(II)-bound nitriles than the related aldonitrones <i>p</i>-R‴C₆H₄CHN­(O)­R″ (R′′ = Me, Ph; R‴ = H, Me), and the difference in the reactivity in 1,3-dipolar cycloaddition (DCA) of the keto- and aldonitrones was interpreted by theoretical calculations and was explained in terms of the orbital arguments as a result of the increase of the HOMO_nitrone energy from aldo- to ketonitrones. The first example of the reversibility in metal-mediated DCA of nitrones to nitriles was observed, and this phenomenon, as follows from the performed theoretical study, is justified by the thermodynamic instability of the Pt^II-bound 3,3-diaryl-2,3-dihydro-1,2,4-oxadiazoles. Metal-free C⁵-diphenyl-2,3-dihydro-1,2,4-oxadiazoles <b>42</b> and <b>43</b> were liberated from corresponding (oxadiazole)₂Pt^II complexes <b>26</b> and <b>30</b> by treatment with excess NaCN, and these heterocycles were characterized by high-resolution ESI⁺-MS and ¹H and ¹³C­{¹H} NMR spectroscopies

Coordination Chemistry of Mercury-Containing Anticrowns. Complexation of Perfluoro‑<i>o</i>,<i>o</i>′‑biphenylenemercury with <i>o</i>‑Xylene and Acetonitrile and the First X‑ray Diffraction Evidence for Its Trimeric Structure

The paper reports the first X-ray diffraction data evidencing the cyclic trimeric structure of the earlier synthesized octafluoro-<i>o</i>,<i>o</i>′-biphenylenemercury (<b>8</b>), being of considerable interest as a potential anticrown. The conclusion on the trimeric (<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₃ structure of this mercuracycle is based on an X-ray structural analysis of its <i>o</i>-xylene and acetonitrile complexes {[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₃]­(<i>o</i>-Me₂C₆H₄)₂} (<b>9</b>) and {[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₃]­(MeCN)₃} (<b>10</b>), which were obtained from <b>8</b> in an analytically pure state and fully characterized. Complex <b>9</b> contains two <i>o</i>-xylene species per one molecule of <b>8</b> and forms in the crystal infinite chains consisting of alternating mercuramacrocycle units and bridging <i>o</i>-xylene ligands. One more <i>o</i>-xylene molecule in each macrocyclic fragment of the chain serves as a terminal ligand. Both bridging and terminal molecules of <i>o</i>-xylene are coordinated in all cases with only one Hg site of the corresponding mercuracycle. The back transformation of complex <b>9</b> into <b>8</b> and <i>o</i>-xylene occurs on its heating in a vacuum at 100–120 °C for 2 h. In contrast to <b>9</b>, complex <b>10</b>, containing three acetonitrile ligands per one molecule of <b>8</b>, has a discrete structure in the crystal. In this complex, two of three acetonitrile species are bonded to one and the same Hg center of <b>8</b>, whereas the third MeCN species is coordinated with the other Hg atom of the mercuramacrocycle

Facile and Reversible 1,3-Dipolar Cycloaddition of Aryl Ketonitrones to Platinum(II)-Bound Nitriles: Synthetic, Structural, and Theoretical Studies

The reaction between <i>trans</i>-[PtCl₂(NCR)₂] (R = Et <b>1</b>, NMe₂ <b>2</b>, NEt₂ <b>3</b>, NC₅H₁₀ <b>4</b>) and the acyclic triaryl ketonitrones Ph₂CN­(O)­C₆H₄R′<i>-p</i> (R′ = H <b>5</b>, Me <b>6</b>, Cl <b>7</b>, OMe <b>8</b>) proceeds as a facile and consecutive two-step intermolecular cycloaddition to give the mono-cycloaddition products <i>trans</i>-[PtCl₂(NCR)­{N^<i>a</i>C­(R)­ON­(C₆H₄R<i>′-p</i>)­C^<i>b</i>Ph₂}]^{(<i>a</i>−<i>b</i>)} (R/R′ = Et/H <b>9</b>, Et/Me <b>10</b>, Et/Cl <b>11</b>, Et/OMe <b>12</b>, NMe₂/H <b>13</b>, NMe₂/Me <b>14</b>, NMe₂/Cl <b>15</b>, NMe₂/OMe <b>16</b>, NEt₂/H <b>17</b>, NEt₂/Me <b>18</b>, NEt₂/Cl <b>19</b>, NEt₂/OMe <b>20</b>, NC₅H₁₀/H <b>21</b>, NC₅H₁₀/Me <b>22</b>, NC₅H₁₀/Cl <b>23</b>, NC₅H₁₀/OMe <b>24</b>) and then the bis-2,3-dihydro-1,2,4-oxadiazole complexes <i>trans</i>-[PtCl₂{N^<i>a</i>C­(R)­ON­(C₆H₄R′<i>-p</i>)­C^<i>b</i>Ph₂}₂]^{(<i>a</i>−<i>b</i>)} (R/R′ = Et/H <b>25</b>, Et/Me <b>26</b>, Et/Cl <b>27</b>, Et/OMe <b>28</b>, NMe₂/H <b>29</b>, NMe₂/Me <b>30</b>, NMe₂/Cl <b>31</b>, NMe₂/OMe <b>32</b>, NEt₂/H <b>33</b>, NEt₂/Me <b>34</b>, NEt₂/Cl <b>35</b>, NEt₂/OMe <b>36</b>, NC₅H₁₀/H <b>37</b>, NC₅H₁₀/Me <b>38</b>, NC₅H₁₀/Cl <b>39</b>, NC₅H₁₀/OMe <b>40</b>). The ketonitrones Ph₂CN­(O)­C₆H₄R′<i>-p</i> were found to be unexpectedly much more reactive toward the platinum­(II)-bound nitriles than the related aldonitrones <i>p</i>-R‴C₆H₄CHN­(O)­R″ (R′′ = Me, Ph; R‴ = H, Me), and the difference in the reactivity in 1,3-dipolar cycloaddition (DCA) of the keto- and aldonitrones was interpreted by theoretical calculations and was explained in terms of the orbital arguments as a result of the increase of the HOMO_nitrone energy from aldo- to ketonitrones. The first example of the reversibility in metal-mediated DCA of nitrones to nitriles was observed, and this phenomenon, as follows from the performed theoretical study, is justified by the thermodynamic instability of the Pt^II-bound 3,3-diaryl-2,3-dihydro-1,2,4-oxadiazoles. Metal-free C⁵-diphenyl-2,3-dihydro-1,2,4-oxadiazoles <b>42</b> and <b>43</b> were liberated from corresponding (oxadiazole)₂Pt^II complexes <b>26</b> and <b>30</b> by treatment with excess NaCN, and these heterocycles were characterized by high-resolution ESI⁺-MS and ¹H and ¹³C­{¹H} NMR spectroscopies

Supramolecular Design of the Trinuclear Silver(I) and Copper(I) Metal Pyrazolates Complexes with Ruthenium Sandwich Compounds via Intermolecular Metal−π Interactions

The interaction of copper­(I) and silver­(I) macrocyclic pyrazolates with aromatic ligands of ruthenium sandwiches (Cp*RuInd, CpRuInd, and Ind₂Ru) in solution is shown for the first time. The similar mode of coordination of macrocycles to the C₆ fragment of indenyl ligand was found both in the solution and in the solid state. Complexation of macrocycles with the nonencumbered sandwiches (CpRuInd, Ind₂Ru) leads to the formation of infinite stacks via alternating molecules of macrocycles and sandwich compounds as one-dimensional coordination polymers with a regular structure. Coordination mode of the indenyl ligand is independent of the second part of the ruthenium sandwich as well as of the aromatic ligand coordinated to another face of the macrocycle. The general principle of macrocycle supramolecular packing suggests coordination of two ligands on both faces of the macrocycle

Reactions of Manganese and Rhenium Vinylidene Complexes with Hydrophosphoryl Compounds

We studied the reactions of manganese and rhenium phenylvinylidenes Cp­(CO)₂MCC­(H)­Ph (<b>Mn1</b> M = Mn; <b>Re1</b> M = Re) with HP­(O)­R₂ (R = C₆F₅, Ph, and OEt) and HP­(S)­Ph₂, which resulted in the selective formation of η²-<i>E</i>-phosphorylalkene complexes Cp­(CO)₂M­{η²-<i>E</i>-H­[R₂(O)­P]­CC­(H)­Ph} (<b>Mn2</b>, <b>Re2</b> R = C₆F₅; <b>Mn3</b>, <b>Re3</b> R = Ph; and <b>Mn6</b>, <b>Re6</b> R = OEt) and Cp­(CO)₂M­{η²-<i>E</i>-H­[Ph₂(S)­P]­CC­(H)­Ph} (<b>Mn5</b>, <b>Re5</b>). The DFT/B3LYP­(6-31G*) analysis showed the model reactions of <b>Mn1</b> with HP­(O)­Me₂ and HP­(O) (OMe)₂ to proceed via the initial transition state Cp­(CO)₂{Ph­(H)­CC}­Mn···HO–PR₂ (<b>TS1</b>) where the minor <b>PA</b> form HO–PR₂ is hydrogen-bonded to the metal, followed by stereoselective (<i>trans</i>- to the phenyl group) addition of the <b>PA</b> phosphorus atom to the C_α-vinylidene atom, which defines both the rate of the process and the anti-Markovnikov structure of the reaction product. The reactions can proceed at a relatively low content of the reactive <b>PA</b> form

Coordination Chemistry of Anticrowns. Synthesis and Structures of Double-Decker Sandwich Complexes of the Three-Mercury Anticrown (<i>o</i>‑C₆F₄Hg)₃ with Halide Anions Containing and Not Containing Coordinated Dibromomethane Molecules

The interaction of the three-mercury anticrown (<i>o</i>-C₆F₄Hg)₃ (<b>1</b>) with [PPh₄]­[BF₄] in methanol at room temperature leads to fluoride anion transfer from BF₄^– to <b>1</b> with the formation of a fluoride complex, [PPh₄]­{[(<i>o</i>-C₆F₄Hg)₃]₂F}, having a double-decker sandwich structure. The fluoride ion in this unique adduct is disposed between the mutually parallel planes of the central nine-membered rings of the anticrown units and cooperatively coordinated by all six Hg sites. The iodide anion also forms a double-decker sandwich in the interaction with <b>1</b>, but this sandwich, [PPh₄]­{[(<i>o</i>-C₆F₄Hg)₃]₂I}, has a wedge-shaped geometry. The reaction of <b>1</b> with [^<i>n</i>Bu₄N]Cl in dibromomethane at −15 °C affords a complex, [^<i>n</i>Bu₄N]­{[(<i>o</i>-C₆F₄Hg)₃]₂Cl­(CH₂Br₂)₂}, containing one chloride anion and two coordinated CH₂Br₂ species per two molecules of <b>1</b>. A similar bromide complex of <b>1</b>, containing two coordinated CH₂Br₂ moieties, has also been synthesized and structurally characterized. Both compounds represent wedge-shaped double-decker sandwiches wherein the halide anion is simultaneously bonded to all Hg centers of the anticrown molecules. The dibromomethane species in the isolated adducts are also arranged in the space between the mercuramacrocycles. One of these species is coordinated by each of its bromine atoms to a single Hg site of the adjacent macrocycle while the other interacts by only one bromine atom with a Hg center of the neighboring molecule of <b>1</b>

Coordination Chemistry of Anticrowns. Synthesis and Structures of Double-Decker Sandwich Complexes of the Three-Mercury Anticrown (<i>o</i>‑C₆F₄Hg)₃ with Halide Anions Containing and Not Containing Coordinated Dibromomethane Molecules

The interaction of the three-mercury anticrown (<i>o</i>-C₆F₄Hg)₃ (<b>1</b>) with [PPh₄]­[BF₄] in methanol at room temperature leads to fluoride anion transfer from BF₄^– to <b>1</b> with the formation of a fluoride complex, [PPh₄]­{[(<i>o</i>-C₆F₄Hg)₃]₂F}, having a double-decker sandwich structure. The fluoride ion in this unique adduct is disposed between the mutually parallel planes of the central nine-membered rings of the anticrown units and cooperatively coordinated by all six Hg sites. The iodide anion also forms a double-decker sandwich in the interaction with <b>1</b>, but this sandwich, [PPh₄]­{[(<i>o</i>-C₆F₄Hg)₃]₂I}, has a wedge-shaped geometry. The reaction of <b>1</b> with [^<i>n</i>Bu₄N]Cl in dibromomethane at −15 °C affords a complex, [^<i>n</i>Bu₄N]­{[(<i>o</i>-C₆F₄Hg)₃]₂Cl­(CH₂Br₂)₂}, containing one chloride anion and two coordinated CH₂Br₂ species per two molecules of <b>1</b>. A similar bromide complex of <b>1</b>, containing two coordinated CH₂Br₂ moieties, has also been synthesized and structurally characterized. Both compounds represent wedge-shaped double-decker sandwiches wherein the halide anion is simultaneously bonded to all Hg centers of the anticrown molecules. The dibromomethane species in the isolated adducts are also arranged in the space between the mercuramacrocycles. One of these species is coordinated by each of its bromine atoms to a single Hg site of the adjacent macrocycle while the other interacts by only one bromine atom with a Hg center of the neighboring molecule of <b>1</b>

Coordination Chemistry of Anticrowns. Isolation of the Chloride Complex of the Four-Mercury Anticrown {[(<i>o</i>,<i>o</i>′‑C₆F₄C₆F₄Hg)₄]Cl}⁻ from the Reaction of <i>o</i>,<i>o</i>′‑Dilithiooctafluorobiphenyl with HgCl₂ and Its Transformations to the Free Anticrown and the Complexes with <i>o</i>‑Xylene, Acetonitrile, and Acetone

The paper reports that the interaction of <i>o</i>,<i>o</i>′-dilithiooctafluorobiphenyl with HgCl₂ in ether results in the formation of the lithium chloride complex Li­{[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄]­Cl} (<b>11</b>) of the four-mercury anticrown (<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄ (<b>12</b>) along with the earlier isolated and characterized three-mercury anticrown (<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₃ (<b>2</b>). The complex was identified by the reaction with 12-crown-4 and determination of the structure of the [Li­(12-crown-4)₂]­{[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄]­Cl} (<b>13</b>) formed. According to an X-ray analysis, the chloride anion in <b>13</b> is simultaneously coordinated with all four Hg centers of the anticrown, forming with them a pyramidal Hg₄Cl fragment. The reaction of <b>11</b> (in the form of an acetonitrile solvate, <b>11</b>·<i>n</i>MeCN) with boiling water leads to removal of LiCl from <b>11</b> and to the formation of free anticrown <b>12</b>, the subsequent recrystallization of which from <i>o</i>-xylene affords the <i>o</i>-xylene complex {[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄]­(<i>o</i>-Me₂C₆H₄)₂} (<b>14</b>). The obtained <b>14</b> forms in the crystal infinite chains consisting of alternating anticrown units and bridging <i>o</i>-xylene moieties. Another <i>o</i>-xylene molecule in each macrocyclic fragment of the chain plays the role of a terminal ligand. In both cases, the <i>o</i>-xylene ligands in <b>14</b> are bonded to only one Hg center of the corresponding mercuramacrocycle. The back-conversion of complex <b>14</b> into <b>12</b> and <i>o</i>-xylene proceeds in the course of its thermal decomposition under vacuum at 100–120 °C. The reaction of <b>12</b> with acetonitrile yields the nitrile complex {[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄]­(MeCN)₂} (<b>15</b>), which also forms infinite polymeric chains in the crystal. In each monomeric unit of the chain, the corresponding bridging nitrile is bonded to only one mercury atom of the anticrown moiety, whereas the other nitrile ligand is coordinated with two Hg sites. The synthesis and structure of the complex {[(<i>o</i>,<i>o</i>′-C₆F₄C₆F₄Hg)₄]­(Me₂CO)₂(H₂O)} (<b>16</b>), containing two acetone and one water ligand per molecule of <b>12</b>, are also reported. Each acetone molecule in <b>16</b> interacts with only one Hg atom of <b>12</b>, while the water molecule is coordinated with two mercury centers and, in addition, forms H-bonds with the oxygen atoms of the acetone species