Synthese und Molekülstrukturen von N‐substituierten Diethylgallium‐2‐pyridylmethylamiden

Synthesis and Molekular Structures of N‐substituted Diethylgallium‐2‐pyridylmethylamides (2‐Pyridylmethyl)(tert‐butyldimethylsilyl)amine ( 1a ) and (2‐pyridylmethyl)‐di(tert‐butyl)silylamine ( 1b ) form with triethylgallane the corresponding red adducts 2a and 2b via an additional nitrogen‐gallium bond. These oily compounds decompose during distillation. Heating under reflux in toluene leads to the elimination of ethane and the formation of the red oils of [(2‐pyridylmethyl)(tert‐butyldimethylsilyl)amido]diethylgallane ( 3a ) and [(2‐pyridylmethyl)‐di(tert‐butyl)silylamido]diethylgallane ( 3b ). In order to investigate the thermal stability solvent‐free 3a is heated up to 400 °C. The elimination of ethane is observed again and the C‐C coupling product N, N′‐Bis(diethylgallyl)‐1, 2‐dipyridyl‐1, 2‐bis(tert‐butyldimethylsilyl)amido]ethan ( 4 ) is found in the residue. Substitution of the silyl substituents by another 2‐pyridylmethyl group and the reaction of this bis(2‐pyridylmethyl)amine with GaEt₃ yield triethylgallane‐diethylgallium‐bis(2‐pyridylmethyl)amide ( 5 ). The metalation product adds immediately another equivalent of triethylgallane regardless of the stoichiometry. The reaction of GaEt₃ with 2‐pyridylmethanol gives quantitatively colorless 2‐pyridylmethanolato diethylgallane ( 6 ).     

Reaktion von Bis(methylzink)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethan mit Triisopropylsilylphosphan und ‐arsan

Reaction of Bis(methylzinc)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane with Triisopropylsilylphosphane and ‐arsane The reaction of bis(methylzinc)‐1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane ( 1 ) with triisopropylsilylphosphane gives the three‐nuclear complex [1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane]trizinc‐bis(μ‐triisopropylsilylphosphanediide) ( 2 ). Two zinc atoms show the coordination number of four whereas the third metal center is located between the two phosphorus atoms with a bent P–Zn–P‐moiety. The reaction of 1 with triisopropylsilylarsane proceeds analoguesly, however, we were not able to isolate analytically pure [1,2‐dipyridyl‐1,2‐bis(tert‐butyldimethylsilylamido)ethane]trizinc‐bis(μ‐triisopropylsilylarsanediide) ( 3 ).     

Synthese und Strukturen von Yttrium‐tris[bis(trimethylsilyl)phosphanid] und 1, 1', 3, 3'‐Tetrakis(trimethylsilyl)yttrocen‐tri(tert‐butyl)silylphosphanid

The metalation of HP(SiMe₃)₂ with Y[CH(SiMe₃)₂]₃ gives the homoleptic {Y[P(SiMe₃)₂]₃}₂ (1) which crystallizes from toluene in the monoclinic space group P2₁/c. The yttrium atoms are in a distorted tetrahedral environment with Y‐P bond lengths of 267.7 and 284.8 pm to the terminal and bridging substituents, respectively. The metathesis reaction of [1, 3‐(Me₃Si)₂C₅H₃]₂YCl with KPSitBu₃ yields (tetrahydrofuran‐O)‐1, 1', 3, 3'‐tetrakis(trimethylsilyl)yttrocene‐tri(tert‐butyl)silylphosphanide ( 2 ). The molecular structure of 2 in solution was deduced by NMR spectroscopy and X‐ray crystallography. The coupling constants ¹J(Y, P) and ¹J(P, H) show values of 144.0 Hz and 201.0 Hz, respectively.     

Dimers linked by type‐I C—F...F—C contacts in (Z)‐3‐methyl‐4‐[2‐(4‐methylphenyl)hydrazinylidene]‐1‐(pentafluorophenyl)‐1H‐pyrazol‐5(4H)‐one

The title compound, C₁₇H₁₁F₅N₄O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N—H...O hydrogen bonds and π–π interactions into dimeric entities, presenting a noticeable noncrystallographic C₂ symmetry. These dimers are in turn linked by a medium‐strength type‐I C—F...F—C interaction into elongated tetramers. Much weaker C—H...F contacts link the tetramers into broad two‐dimensional substructures parallel to (101).     

Organo‐Palladium(II)‐Verbindungen mit PdC4‐Koordination: Phenylethinyl‐ und Methylphenylethinylkomplexe

Tetrakis(p‐tolyl)oxalamidinato‐bis[acetylacetonatopalladium(II)] ([Pd₂(acac)₂(oxam)]) reacted with Li–C≡C–C₆H₅ in THF with formation of [Pd(C≡C–C₆H₅)₄Li₂(thf)₄] ( 1a ). Reaction of [Pd₂(acac)₂(oxam)] with a mixture of 6 equiv. Li–C≡C–C₆H₅ and 2 equiv. LiCH₃ resulted in the formation of [Pd(CH₃)(C≡C–C₆H₅)₃Li₂(thf)₄] ( 2 ), and the dimeric complex [Pd₂(CH₃)₄(C≡C–C₆H₅)₄Li₄(thf)₆] ( 3 ) was isolated upon reaction of [Pd₂(acac)₂(oxam)] with a mixture of 4 equiv. Li–C≡C–C₆H₅ and 4 equiv. LiCH₃. 1 – 3 are extremely reactive compounds, which were isolated as white needles in good yields (60–90%). They were fully characterized by IR, ¹H‐, ¹³C‐, ⁷Li‐NMR spectroscopy, and by X‐ray crystallography of single crystals. In these compounds Li ions are bonded to the two carbon atoms of the alkinyl ligand. 1a reacted with Pd(PPh₃)₄ in the presence of oxygen to form the already known complexes trans‐[Pd(C≡C–C₆H₅)₂(PPh₃)₂] and [Pd(η²‐O₂)(PPh₃)₂]. In addition, 1a is an active catalyst for the Heck coupling reaction, but less active in the catalytic Sonogashira reaction.     

Kristallstrukturen und spektroskopische Eigenschaften von 2λ3‐Phospha‐1, 3‐dionaten und 1, 3‐Dionaten des Calciums ‐ ein Vergleich am Beispiel der 1, 3‐Diphenyl‐ und 1, 3‐Di(tert‐butyl)‐Derivate

Crystal Structures and Spectroscopic Properties of 2λ³‐Phospha‐1, 3‐dionates and 1, 3‐Dionates of Calcium ‐ Comparative Studies on the 1, 3‐Diphenyl and 1, 3‐Di(tert‐butyl) Derivatives A hydrogen‐metal exchange between dibenzoylphosphane and calcium carbide in tetrahydrofuran (THF) followed by addition of the ligand 1, 3, 5‐trimethyl‐1, 3, 5‐triazinane (TMTA) furnishes the binuclear complex bis[(tmta‐N, N′, N″)calcium bis(dibenzoylphosphanide)] ( 1a ) co‐crystallizing with benzene. Similarly, reaction of bis(2, 2‐dimethylpropionyl)phosphane with bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in 1, 2‐dimethoxyethane (DME) gives bis(dme‐O, O′)calcium bis[bis(2, 2‐dimethylpropionyl)phosphanide] ( 1b ) in high yield. The carbon analogues 1, 3‐diphenylpropane‐1, 3‐dione (dibenzoylmethane) or 2, 2, 6, 6‐tetramethylheptane‐3, 5‐dione (dipivaloylmethane) and bis(thf‐O)calcium bis[tris(trimethylsilylmethyl)zincate] in DME afford bis(dme‐O, O′)calcium bis(dibenzoylmethanide) ( 2a ) and the binuclear complex (μ‐dme‐O, O′)bis[(dme‐O, O′)calcium bis(dipivaloylmethanide)] ( 2b ), respectively. Dialkylzinc formed during the metalation reaction shows no reactivity towards the 1, 3‐dionates 2a and 2b . Finally, from the reaction of the unsymmetrically substituted ligand 2‐(methoxycarbonyl)cyclopentanone and bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in toluene, the trinuclear complex 3 is obtained, co‐crystallizing with THF. The β‐ketoester anion bridges solely via the cyclopentanone unit.     

Ligandverhalten von P‐funktionellen Organozinnhalogeniden: Nickel(II)‐, Palladium(II)‐ und Platin(II)‐halogenid‐Komplexe mit Me2(Cl)SnCH2CH2PPh2

Ligand Behaviour of P‐functional Organotin Halides: Nickel(II), Palladium(II), and Platinum(II) Complexes with Me₂(Cl)SnCH₂CH₂PPh₂ Me₂(Cl)SnCH₂CH₂PPh₂ ( 1 ) reacts with Ni^II, Pd^II, and Pt^II halides in molar ratio 2 : 1 forming the complexes [MX₂{PPh₂CH₂CH₂Sn(Cl)Me₂}₂] (M = Ni, Pd, Pt; X = Cl, Br) ( 3 – 6 , 9 , 10 ) ( 7 , 8 : M = Ni; Br instead of Cl). The nickel complexes were isolated and characterized both as the planar ( 3 , 5 , 7 ) and the tetrahedral ( 4 , 6 , 8 ) isomer. Crystal structure analyses and NMR data indicate for the planar nickel complexes 3 , 5 , 7 and [MCl₂{PPh₂CH₂CH₂Sn(Cl)Me₂}₂] ( 9 : M = Pd; 10 : M = Pt) the existence of intra and intermolecular M–Hal…Sn bridges. In a ligand : metal molar ratio of 3 : 1 the complexes [M^éCl{PPh₂CH₂CH₂Sn^⊖Cl₂Me₂}{PPh₂CH₂CH₂Sn(Cl)Me₂}₂] ( 11 : M = Pd; 12 : M = Pt) are formed which represent intramolecular ion pairs. By dehalogenation of [PdCl₂{PPh₂CH₂CH₂Sn(Cl)Me₂}₂] ( 9 ) with sodium amalgam and graphite potassium (C₈K), respectively, the palladacycles cis‐[Pd{PPh₂CH₂CH₂SnMe₂}₂] ( 13 ) and trans‐[Pd(Cl)PPh₂CH₂CH₂SnMe₂{PPh₂CH₂CH₂Sn(Cl)Me₂}] ( 14 ) are formed. From the compounds 1 , 3 , 9 , 11 , and 12 the crystal structures are determined. All compounds are characterized by ¹H, ³¹P, and ¹¹⁹Sn NMR spectroscopy.     

Syntheses,Crystal Structure and Reactivity of Tin(II) Bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide]

Metallation of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with n‐butyllithium in toluene yields lithium N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 1 ), which crystallizes as a tetramer. Transamination of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with an equimolar amount of Sn[N(SiMe₃)₂]₂ leads to the formation of monomeric bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ). The addition of another equivalent of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine gives homoleptic tin(II) bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide] ( 3 ). In these complexes the N‐(diphenylphosphanyl)(2‐pyridylmethyl)amido groups act as bidentate bases through the nitrogen bases. At elevated temperatures HN(SiMe₃)₂ is liberated from bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ) yielding mononuclear tin(II) 1,2‐dipyridyl‐1,2‐bis(diphenylphosphanylamido)ethane ( 4 ) through a C–C coupling reaction. The three‐coordinate tin(II) atoms of 2 and 4 adopt trigonal pyramidal coordination spheres.     

Sequential 1,4‐/1,2‐Addition of Lithium(trimethylsilyl)diazomethane onto Cyclic Enones to Induce C−C Fragmentation and N−Li Insertion

α,β‐Unsaturated ketones generally undergo addition reactions with nucleophiles with a preference for either 1,2‐ or 1,4‐addition, but rarely both. However, the right combination of reagents allows for consecutive 1,4‐ and 1,2‐additions to occur: Cyclic α,β‐unsaturated ketones undergo double additions with lithium(trimethylsilyl)diazomethane, effectively generating various molecular frameworks with complexity and diversity. Owing to the sequential generation of several intermediates of multifaceted reactivity, including diazoalkane derivatives and alkylidene carbenes, it is possible to induce novel Grob‐type C?C fragmentations, alkylidene carbene mediated Li?N insertions, and dipolar cycloadditions by controlling the reaction parameters.     

Rhodium(III)‐Catalyzed Directed C−H Amidation of N‐Nitrosoanilines and Subsequent Formation of 1,2‐Disubstituted Benzimidazoles

An efficient rhodium‐catalyzed direct C−H amidation of N ‐nitrosoanilines with 1,4,2‐dioxazol‐5‐ones as amidating agents has been developed. This method featured mild reaction conditions, a wide substrate scope and satisfactory yields. Besides, the amidated products could be readily converted to pharmaceutically valuable 1,2‐disubstituted benzimidazoles via an HCl‐mediated deprotection/cyclization process in one pot.     

Synthese und Kristallstruktur von Mangan(II)‐ und Zinkamid,Mn(NH2)2 und Zn(NH2)2

Synthesis and Crystal Structure of Manganese(II) and Zinc Amides, Mn(NH₂)₂ and Zn(NH₂)₂ Metal powders of manganese resp. zinc react with supercritical ammonia in autoclaves in the presence of a mineralizer Na₂Mn(NH₂)₄ resp. Na₂Zn(NH₂)₄_.0.5NH₃ to well crystallized ruby‐red Mn(NH₂)₂ (p(NH₃) = 100 bar, T = 130°C, 10 d) resp. colourless Zn(NH₂)₂ (p(NH₃) = 3.8 kbar, T = 250°C, 60 d). The structures including all H‐positions were solved by x‐ray single crystal data: Mn(NH₂)₂: I4₁/acd, Z = 32, a = 10.185(6) Å, c = 20.349(7) Å, N(F_o) with F > 3σ (F) = 313, N(parameter) = 45, R/R_w = 0.038/0.043. Zn(NH₂)₂: I4₁/acd, Z = 32, a = 9.973(3) Å, c = 19.644(5) Å, N(F_o) with F > 3σ (F) = 489, N(parameter) = 45, R/R_w = 0.038/0.043. Both compounds crystallize isotypic with Mg(NH₂)₂ [1] resp. Be(NH₂)₂ [2]. Nitrogen of the amide ions is distorted cubic close packed. One quarter of tetrahedral voids is occupied by Mn²⁺‐ resp. Zn²⁺‐ions in such an ordered way that units M₄(NH₂)₆(NH₂)_4/2 occur. The H‐atoms of the anions have such an orientation that the distance to neighboured cations is optimum.     

Monomeric Homoleptic (2‐Pyridylmethyl)(tert‐butyldimethylsilyl)amido Complexes of the Divalent Metals Mg,Mn, Fe,Co, and Zn

The transamination reaction of M[N(SiMe₃)₂]₂ with (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amine yields the corresponding homoleptic metal bis[(2‐pyridylmethyl)(tert‐butyldimethylsilyl)amides] of Mg ( 1 ), Mn ( 2 ), Fe ( 3 ), Co ( 4 ) and Zn ( 5 ). All these compounds crystallize from hexane isotypic in the space group C2/c. From toluene the zinc derivative precipitates as toluene solvate 5 ·toluene. The molecular structures of these compounds are very similar with large NMN angles to the amide nitrogen atoms with NMN values of 148° ( 1 ) and 150° ( 5 ) for the diamagnetic compounds and 156° for the paramagnetic derivatives 2 and 3 . The Co derivative 4 displays a rather small NCoN angle of 142°. Different synthetic routes have been explored for compound 3 which is also available via the metallation reaction of bis(2,4,6‐trimethylphenyl)iron with (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amine and via the metathesis reaction of lithium (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amide with [(thf)₂FeCl₂]. In course of the metathesis reaction, an equimolar amount of lithium (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amide and [(thf)₂FeCl₂] yields heteroleptic (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amido iron(II) chloride ( 6 ) which crystallizes as a centrosymmetric dimeric molecule. The oxidative C‐C coupling reaction of 5 with Sn[N(SiMe₃)₂]₂ leads to the formation of tin(II) 1,2‐bis(2‐pyridyl)‐1,2‐bis(tert‐butyldimethylsilylamido)ethane, tin metal and Zn[N(SiMe₃)₂]₂.     

Koordinationspolymere 1, 2‐Dithiooxalato‐ und 1, 2‐Dithioquadratato‐Komplexe. Synthese und Strukturen von [BaCr2(bipy)2(1, 2‐dtox)4(H2O)2], [Ni(cyclam)(1, 2‐dtsq)]·2DMF, [Ni(cyclam)Mn(1, 2‐dtsq)2(H2O)2]·2H2O und [H3O][H5O2][Cu(cyclam)]3[Cu2(1, 2‐dtsq)3]2

Coordination Polymeric 1, 2‐Dithiooxalato and 1, 2‐Dithiosquarato Complexes. Syntheses and Structures of [BaCr₂(bipy)₂(1, 2‐dtox)₄(H₂O)₂], [Ni(cyclam)(1, 2‐dtsq)]·2DMF, [Ni(cyclam)Mn(1, 2‐dtsq)₂(H₂O)₂]·2H2₂, and [H₃O][H₅O₂][Cu(cyclam)]₃[Cu₂(1, 2‐dtsq)₃]₂ 1, 2‐Dithioxalate and 1, 2‐dithiosquarate ions have a pair of soft and hard donor centers and thus are suited for the formation of coordination polymeric complexes containing soft and hard metal ions. The structures of four compounds with building blocks containing these ligands are reported: In [BaCr₂(bipy)₂(1, 2‐dtox)₄(H₂O)₂] Barium ions and pairs of Cr(bipy)(1, 2‐dtox)₂ complexes form linear chains by the bisbidentate coordination of the dithiooxalate ligands towards Ba²⁺ and Cr³⁺. In [Ni(cyclam)(1, 2‐dtsq)]·2DMF short NÖH···O hydrogen bonds link the NiS₂N₄‐octahedra with C_2v‐symmetry to an infinite chain. In [Ni(cyclam)Mn(1, 2‐dtsq)₂(H₂O)₂]·2H₂O the 1, 2‐dithiosquarato ligand shows a rare example of S‐coordination towards manganese(II). The sulfur atoms of cis‐MnO₂S₄‐polyedra are weakly coordinated towards the axial sites of square‐planar NiN₄‐centers, thus forming a zig‐zag‐chain of Mn···Ni···Mn···Ni polyhedra. [H₃O][H₅O₂][Cu (cyclam)]₃[Cu₂(1, 2‐dtsq)₃]₂ contains square planar [Cu^II(cyclam)]²⁺ ions and dinuclear [Cu^I₂(1, 2‐dtsq)₃]^4— ions. Here each copper atom is trigonally planar coordinated by S‐donor atoms of the ligands. The Cu…Cu distance is 2.861(4)Å.     

Aluminiumhydrazide. Bildung eines dimeren Di(tert‐butyl)aluminiumhydrazids mit viergliedrigem Al2N2‐Heterozyklus und Umsetzung eines Dialkylaluminiumchlorids mit Dilithium‐bis(trimethylsilyl)hydrazid

Aluminium Hydrazides – Formation of a Dimeric Di( tert ‐butyl)aluminium Hydrazide Containing a Four‐Membered Al₂N₂ Heterocycle and Reaction of Dialkylaluminium Chloride with Dilithium Bis(trimethylsilyl)hydrazide The reaction of di(tert‐butyl)aluminium chloride with tert‐butylhydrazine yielded an adduct ( 1 ) which was isolated in a pure form and characterized by crystal structure determination. 1 reacted with n‐butyllithium by deprotonation and salt elimination to give the corresponding di(tert‐butyl)aluminium hydrazide ( 2 ), which is a dimer in solution and in the solid state and possesses a four‐membered Al₂N₂ heterocycle with two exocyclic N–N bonds. The structure of 2 differs from that of other di(tert‐butyl)aluminium hydrazides which have four‐ or five‐membered heterocycles. Treatment of impure samples of 1 with n‐butyllithium yielded by the cleavage of the N–N bonds a mixture of several unknown products, from which the dimeric, centrosymmetric aluminium amide [(Me₃C)₂AlN(H)CMe₃]₂ ( 3 ) was isolated. A similar product ( 4 ) was obtained in a low yield by the reaction of (Me₃SiCH₂)₂AlCl with the dilithium hydrazide Li₂N₂(SiMe₃)₂. An intact N–N bond was neither found in the second product isolated from this reaction. Instead a tricyclic compound was formed by C–H activation which has two five‐membered AlNSiC₂ heterocycles bridged by Al–N bonds.