Synthesis and Reactivity of a Neutral,Three‐Coordinate Platinum(II) Complex Featuring Terminal Amido Ligation

A crystallographically characterized three‐coordinate, formally 14 electron Pt^II complex 1 featuring terminal amido ligation is reported. Computational analysis revealed relatively weak π donation from the amide lone pair to platinum and supports a 14‐electron assignment for 1 . Stoichiometric reactivity studies confirmed the viability of net O? H and C? H addition across, as well as isonitrile insertion into, the terminal platinum–amido linkage of 1 .     

Reactions of Complex Ligands. Part 107 Densely Substituted Hydroquinoid Phenanthrene and Triphenylene Cr(CO)3 Complexes: Chromium‐Templated Synthesis and Molecular Structure

Densely substituted hydroquinoid phenanthrene ( 10 – 18 ), acephenanthrene ( 19 ), and triphenylene chromium tricarbonyl complexes ( 20 – 22 ) have been prepared via benzannulation of naphthalenyl ( 1 – 7 ), acenaphthenyl ( 8 ) and phenanthrenyl carbene complexes ( 9 ), respectively. The naphthalenyl, acenaphthenyl and phenanthrenyl carbene complexes 1 – 9 were obtained in 52–88 % yield starting from commercially available bromoarenes by dehalolithiation, addition of hexacarbonyl chromium to the lithioarene and O‐alkylation of the resulting acyl chromates with trimethyloxonium tetrafluoroborate (Fischer route). The benzannulation of the aryl carbene complexes (either with 3‐hexyne / (t‐butyl)dimethylsilyl chloride or with (t‐butyl)dimethylsilylethyne) allowed the regiospecific synthesis of the oligocyclic hydroquinoid arene tricarbonyl chromium complexes 10 – 22 in 44–94 % yield thus providing a two‐step synthesis with overall yields of 18 ‐ 80 %. Under the kinetic reaction conditions used the metal atom is exclusively coordinated to the persubstituted terminal hydroquinoid ring. The molecular structures of phenanthrene complexes 10 , 12 – 14 , and 16 , acephenanthrene complex 19 , and triphenylene complexes 20 and 21 in the solid state have been determined by X‐ray crystallography. The carbonyl ligands either adopt an eclipsed ( 10 , 12 , 14 , 16 , 19 , 20 ) or staggered ( 13 , 21 ) exo‐conformation pointing away from the center of the phenanthrene, acephenanthrene and triphenylene ligands, respectively. The coordination of the metal atom to the hydroquinoid ring is unsymmetric with the largest metal‐carbon distances found between the chromium atom and one bridgehead carbon and the ring carbon atom bearing the bulky (t‐butyl)dimethylsilyloxy (TBDMSO) substituent.     

Synthesis,Structure, and Physical Properties of a Barium Complex with 5‐Sulfoisophthalic Acid Sodium Salt

The complex [Ba₃(sip)₂(H₂O)₉] · H₂O ( 1 ) (NaH₂sip = 5‐sulfoisophthalic acid sodium) was synthesized and characterized by single‐crystal X‐ray diffraction. Structural determination reveals that the asymmetric unit in 1 contains two crystallographically independent Ba^II atoms. The Ba1 atom is eight‐coordinate with distorted monocapped pentagonal bipyramidal arrangement, whereas the Ba2 atom is ten‐coordinated with bicapped tetragonal prismatic arrangement. The two carboxylate groups of sip^3– adopt different coordination modes, μ₂‐η¹:η¹‐bridging, and μ₂‐η²:η¹‐bridging. The sulfonate group coordinates to three different Ba^II atoms in a tridentate μ₃ mode to generate a ladder‐like one‐dimensional chain. The chains are connected by μ₂‐η¹:η¹‐bridging carboxylate groups to form a wave‐like two‐dimensional network, which are further linked by sip^3– anions to generate a three‐dimensional structure. The thermal stability and luminescence properties of complex 1 were also investigated.     

Different Types of Coordinated Urea Molecules in its Complexes with Rare‐Earth Iodides and Perchlorates

An earlier reported series of the [Ln(Ur)₄(H₂O)₄]I₃ (Ln = Y, La, Nd, Eu, Gd, Dy, Ho, Er; Ur = urea) complexes was completed with seven new compounds (Ln = Ce, Pr, Sm, Tb, Tm, Yb, Lu); one of them, [Ce(Ur)₄(H₂O)₄]I₃, was studied by X‐ray diffraction. The most striking feature of the [Ln(Ur)₄(H₂O)₄]I₃ structures is the presence of two types of coordinated urea molecules. There are two planar symmetric and two non‐planar asymmetric urea molecules. The Ln–O–C bond angles vary in the ranges 163.06–165.71° and 148.42–152.42° for symmetric and asymmetric urea ligands, respectively, correlating with the ionic mode of urea coordination. To elucidate the role of aqua ligands for the urea coordination mode, two water‐free perchlorate complexes, [La(Ur)₈](ClO₄)₃ · 2Ur and [La(Ur)₇(OClO₃)](ClO₄)₂ were synthesized and structurally characterized. In these complexes, all urea molecules are planar symmetric; however, both covalent and ionic types of urea coordination with the La–O–C bond angles varying in the 132.4–142.3° and 145.5–159.1° ranges, respectively can be observed.     

Memory of Chirality in Electron Transfer Mediated Benzylic Umpolung Reactions of Arene–Cr(CO)3 Complexes

As density functional calculations suggest , Cr(CO)₃-complexed benzylic radicals (such as 2 ) exhibit a significant degree of configurational stablility. This was exploited in an efficient method for the electron transfer mediated transformations of readily available 1-arylalkanol–Cr(CO)₃ derivatives 1 to afford alkylated products 3 in good yields and with a high degree of stereochemical retention.     

Stereoselective Arene‐Forming Aldol Condensation: Synthesis of Configurationally Stable Oligo‐1,2‐naphthylenes

Structurally well‐defined oligomers are fundamental for the functionality of natural molecular systems and key for the design of synthetic counterparts. Herein, we describe a strategy for the efficient synthesis of individual stereoisomers of 1,2‐naphthylene oligomers by iterative building block additions and consecutive stereoselective arene‐forming aldol condensation reactions. The catalyst‐controlled atropoenantioselective and the substrate‐controlled atropodiastereoselective aldol condensation reaction provide structurally distinct ter‐ and quaternaphthalene stereoisomers, which represent configurationally stable analogues of otherwise stereodynamic, helically shaped ortho‐phenylenes.     

Darstellung und Strukturen von (η6‐Diaren)TiII‐bis(tetrachloroaluminat)Komplexen,Diaren = Biphenyl oder 3,5,3′,5′‐Tetramethyl‐biphenyl

Syntheses and Crystal Structures of (η⁶‐Diarene)Ti^II‐bis(tetrachloroaluminate) Complexes, Diarene = Biphenyl or 3,5,3′,5′‐Tetramethyl‐biphenyl Syntheses of (η⁶‐diarene)Ti^II(AlCl₄)₂ complexes were performed by the Fischer‐Hafner method. The diarenes employed were biphenyl and 3,5,3′,5′‐tetramethyl‐biphenyl. In each of the resulting complexes, (η⁶‐C₁₂H₁₀)Ti^II(AlCl₄)₂ ( 1 ) and (η⁶‐C₁₆H₁₈)Ti^II(AlCl₄)₂ ( 2 ), only one C₆‐ring of a diarene is coordinatively active. 1 : Space group Pbca, Z = 8, lattice constants at 20 °C: a = 16.864(3), b = 13.931(3), c = 18.807(3) Å; R₁ = 0.048. 2 : Space group P2₁/n, Z = 4, lattice constants at 20 °C: a = 9.775(1), b = 13.720(1), c = 20.214(1) Å; β = 95.50(1)°; R₁ = 0.050.     

Rhodium‐Catalyzed Highly Diastereo‐ and Enantioselective Synthesis of a Configurationally Stable S‐Shaped Double Helicene‐Like Molecule

An S‐shaped double helicene‐like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex‐catalyzed highly diastereo‐ and enantioselective intramolecular double [2+2+2] cycloaddition of a 2‐naphthol‐ and benzene‐linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S‐shaped double helicene‐like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S‐shaped double helicene‐like molecule forms a trimer through the multiple C?H???π and C?H???O interactions in the solid‐state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S‐shaped double helicene‐like molecule enhanced the chiroptical properties.     

Enantiomerically Pure Cyclic trans-1,2-Diols,Diamines, and Amino Alcohols by Intramolecular Pinacol Coupling of Planar Chiral Mono-Cr(CO)3 Complexes of Biaryls

Without any formation of stereoisomers , the intramolecular pinacol cyclization of 1 —planar chiral mono-Cr(CO)₃ complexes of 1,1′-biphenyls with carbonyl functionalities at the 2- and 2′-positions—with samarium diiodide gives cyclic trans-1,2-diols 2 . Upon exposure to sunlight, the chromium-complexed diols 2 produce optically pure chromium-free trans-diols 3 . Similarly, the corresponding enantiomerically pure trans-1,2-diamines and amino alcohols are obtained from the planar chiral chromium complexes of biphenyls with diimino or keto-imino functionalities. R¹=H, OMe; R²=H, Me; R³=H, Me.     

Synthesis and Properties of Lanthanum– Pyrene Complexes—Structure of [(Cp*La)3(μ-Cl)3(thf)(μ-η2:η6:η6-C16H10)], the First Complex with a Pyrene Trianion

Different bonding modes are characteristic for the lanthanum centers of the title compound, a trinuclear lanthanum–pyrene complex in which an arene trianion is present for the first time (see picture for the structure). Thus, La1 and La3 reside in a tetrahedral environment, the La2 center in a distorted trigonal-bipyramidal one.     

Oxalato‐ und Quadratato‐Komplexe hochkoordinierter Metallionen: Die Raumnetzstrukturen von La2(C2O4)(C4O4)2(H2O)8 · 2,5 H2O und K[Bi(C2O4)2] · 5 H2O

Oxalato‐ and Squarato‐Bridged Threedimensional Networks: The Crystal Structures of La₂(C₂O₄)(C₄O₄)₂(H₂O)₈ · 2.5 H₂O and K[Bi(C₂O₄)₂] · 5 H₂O The title compounds have been formed by hydrolysis of amino‐ and thioderivatives of squaric acid in the presence of La^III and Bi^III ions. Both compounds are threedimensional coordination polymers in the solid state, as shown by single crystal X‐ray crystallography. In La₂(C₂O₄)(C₄O₄)₂(H₂O)₈ · 2.5 H₂O oxalato‐bridged pairs of LaO₉ polyhedra are connected with identical neighbouring polyhedra by squarate ions. In K[Bi(C₂O₄)₂] · 5 H₂O each Bi atom is fourfold linked to other Bi atoms by the oxalate ions. The resulting 3D network shows a diamond‐like topology with square‐shaped channels. In both structures the channels are partially filled by water molecules.     

Four Dysprosium(III) Compounds Based On 1H‐Benzimidazole‐5,6‐dicarboxylic Acid via Hydrothermal Synthesis

Four compounds [Dy(H₂bidc)(Hbidc)(H₂O)₈] · 8H₂O ( 1 ), {[Dy(Hbidc)(H₂O)₂(Htzac)] · 3H₂O}_n ( 2 ), [Dy(C₂O₄)_0.5(Hbidc)(H₂O)₃]_n ( 3 ), {[Dy₂(Hbidc)₂(H₂O)(SO₄)] · H₂O}_n ( 4 ) (H₃bidc = 1H‐benzimidazole‐5,6‐dicarboxylic acid, H₂tzac = 1H‐3‐amino‐5‐carboxy‐1,2,4‐triazole) were synthesized with hydrothermal synthesis and structurally characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. X‐ray analysis revealed that the four coordination compounds have different structures: Compound 1 is a three dimensional supermolecular structure joined by hydrogen bonding interactions based upon dinuclear units. Compound 2 is a three dimensional supermolecular structure combined by hydrogen‐bonding interactions based upon one dimensional coordination chain including a T4(1)‐type water cluster chain. The structure of compound 3 is built of two dimensional (3,6)‐connected kgd‐type (4³)₂(4⁶.6⁶.8³) layers with a right‐handed and a left‐handed helical chain, which are further extended into three dimensional supramolecular architecture by hydrogen bonding interactions. Compound 4 displays a three dimensional framework containing a dinuclear dysprosium building unit with a (3,8)‐connected (4.5²)₂(4².5¹⁰.6¹².7.8³) topological framework. In addition, the photoluminescent property of compound 3 was investigated.     

The Cobalt cyclo‐P4 Sandwich Complex and Its Role in the Formation of Polyphosphorus Compounds

A synthetic approach to the sandwich complex [Cp′′′Co(η⁴‐P₄)] ( 2 ) containing a cyclo‐P₄ ligand as an end‐deck was developed. Complex 2 is the missing homologue in the series of first‐row cyclo‐P_n sandwich complexes, and shows a unique tendency to dimerize in solution to form two isomeric P₈ complexes [(Cp′′′Co)₂(μ,η⁴:η²:η¹‐P₈)] ( 3 and 4 ). Reactivity studies indicate that 2 and 3 react with further [Cp′′′Co] fragments to give [(Cp′′′Co)₂(μ,η²:η²‐P₂)₂] ( 5 ) and [(Cp′′′Co)₃P₈] ( 6 ), respectively. Furthermore, complexes 2 , 3 , and 4 thermally decompose forming 5 , 6 , and the P₁₂ complex [(Cp′′′Co)₃P₁₂] ( 7 ). DFT calculations on the P₄ activation process suggest a η³‐P₄ Co complex as the key intermediate in the synthesis of 2 as well as in the formation of larger polyphosphorus complexes via a unique oligomerization pathway.     

Optically Active Transition Metal Complexes. 128 [1] Synthesis,Characterization and Molecular Structures of Cycloheptatrienyl‐Iminphos‐Molybdenum Complexes Differing Only in the Metal Configuration

The chiral‐at‐metal cycloheptatrienyl‐molybdenum complexes (R_Mo, S_C)‐[(η⁷‐C₇H₇)Mo(iminphos)(CO)]BF₄ ( 2a ) and (S_Mo, S_C)‐[(η⁷‐C₇H₇)Mo(iminphos)(CO)]BF₄ ( 2b ) (iminphos = 2‐[N‐(S)‐1‐phenylethylcarbaldimino]phenyl(diphenyl)phosphane), which only differ in the molybdenum configuration, were prepared and separated by fractional crystallization. The absolute configuration for both diastereomers was determined by X‐ray analysis. ¹H NMR studies demonstrated the configurational lability at the molybdenum centre in solution.