Dative bonds versus electron solvation in tri‐coordinated beryllium complexes: Be(CX)3 [X = O,S, Se,Te, Po] and Be(PH3)3 versus Be(NH3)3

The formation mechanism and bonding scheme for the titled molecules is proposed based on high‐level theoretical calculations. All species are formed via three dative bonds from the ligands to Be. For Be(CX)₃ [X = O, S, Se, Te, Po] species and Be(PH₃)₃ the two electrons of beryllium are promoted from 2s to 2p facilitating these bonds. At the same time, electronic density is donated toward the ligands via the π‐frame. In contrast, ammonia partly solvates the valence 2s electrons of Be, which are delocalized in the periphery of the molecule. Based on the proton affinity of all of these complexes and their derivatives, we found that they are strong Lewis bases. For example, Be(PMe₃)₃ is stronger than ammonia and its ethyl substituted analogue and could serve as the basis of more efficient frustrated Lewis pairs.     

Phosphanimin‐ und Phosphaniminato‐Komplexe von Beryllium. Kristallstrukturen von [BeCl2(HNPPh3)2], [BeCl(HNPPh3)2(Py)]Cl und [Be3Cl2(NPPh3)4]

Phosphanimine and Phosphoraneiminato Complexes of Beryllium. Crystal Structures of [BeCl₂(HNPPh₃)₂], [BeCl(HNPPh₃)₂(Py)]Cl, and [Be₃Cl₂(NPPh₃)₄] Tetraphenylphosphonium hexachlorodiberyllate, (Ph₄P)₂[Be₂Cl₆], reacts with lithium phosphoraneiminate, [LiNPPh₃]₆, in dichloromethane to give the three‐nuclear beryllium phosphoraneiminate [Be₃Cl₂(NPPh₃)₄] ( 3 ). As a by‐product the phosphaneimine complex [BeCl₂(HNPPh₃)₂] ( 1 ) can be isolated, which reacts with pyridine to give the ionic complex [BeCl(HNPPh₃)₂(Py)]Cl ( 2 ). On the other hand, the silylated phosphanimine Me₃SiNP(p‐tolyl)₃ ( 5 ) does not react with BeCl₂ or (Ph₄P)₂[Be₂Cl₆] forming the expected phosphoraneiminates. From CH₂Cl₂ solutions only the amino‐phosphonium salt [(C₇H₇)₃PNH₂]Cl ( 4 ) can be obtained. The compounds 1 ‐ 5 are characterized by single X‐ray analyses and by IR spectroscopy. 1 ·C₇H₈: Space group C2/c, Z = 4, lattice dimensions at 193 K: a = 1408.9(2), b = 1750.9(2), c = 1633.2(2) pm, β = 106.50(1)°; R₁ = 0.0385. 1 forms a molecular structure with short Be—N distances of 169.8(3) pm. 2 ·Py: Space group P1¯, Z = 4, lattice dimensions at 193 K: a = 969.5(1), b = 2077.1(2), c = 2266.4(2) pm, α = 72.24(1)°, β = 87.16(1)°, γ = 77.42(2)°, R₁ = 0.0776. 2 forms ion pairs in which the NH atoms of the phosphaneimine ligands act as hydrogen bridges with the chloride ion. The HNPPh₃ ligand realizes short Be—N bonds of 169.0(6) pm, the Be—N distance of the pyridine molecule is 182.5(6) pm. 3 ·3CH₂Cl₂: Space group P1¯, Z = 2, lattice dimensions at 193 K: a = 1333.2(2), b = 1370.2(2), c = 2151.8(3) pm, α = 107.14(1)°, β = 91.39(1)°, γ = 105.15(1)°, R₁ = 0.0917. The structure of the three‐nuclear molecule 3 corresponds with a Be²⁺ ion which is tetrahedrally coordinated by the nitrogen atoms of two {ClBe(NPPh₃)₂}^— chelates. 4 ·CH₂Cl₂: Space group P2₁/c, Z = 4, lattice dimensions at 193 K: a = 1206.6(2), b = 1798.0(2), c = 1096.2(1) pm, β = 97.65(1)°, R₁ = 0.0535. 4 forms dimeric units in which the NH₂ groups of the [(C₇H₇)₃PNH₂]⁺ cations act as hydrogen bridges with the chloride ions to give centrosymmetric eight‐membered rings. 5 : Space group P2₁/n, Z = 4, lattice dimensions at 193 K: a = 1074.3(2), b = 2132.2(3), c = 1075.5(2) pm, β = 110.68(1)°, R₁ = 0.0664. 5 forms molecules with distances PN of 154.6(3), SiN of 168.8(3) pm, and bond angle SiNP of 134.4(2)°.     

Neue phosphidoverbrückte Mehrkernkomplexe des Ag und Zn. Die Kristallstrukturen von [Ag3(PPh2)3(PnBu2tBu)3], [Ag4(PPh2)4(PR3)4] (PR3 = PMenPr2, PnPr3), [Ag4(PPh2)4(PEt3)4]n, [Zn4(PPh2)4Cl4(PRR2)2] (PRR′2 = PMenPr2, PnBu3, PEt2Ph), [Zn4(PhPSiMe3)4Cl4(C4H8O)2] und [Zn4(PtBu2)4Cl4]

New Phosphido-bridged Multinuclear Complexes of Ag and Zn. The Crystal Structures of [Ag₃(PPh₂)₃(PⁿBu₂^tBu)₃], [Ag₄(PPh₂)₄(PR₃)₄] (PR₃ = PMeⁿPr₂, PⁿPr₃), [Ag₄(PPh₂)₄(PEt₃)₄]_n, [Zn₄(PPh₂)₄Cl₄(PRR′₂)₂] (PRR′₂ = PMeⁿPr₂, PⁿBu₃, PEt₂Ph), [Zn₄(PhPSiMe₃)₄Cl₄(C₄H₈O)₂] and [Zn₄(P^tBu₂)₄Cl₄] AgCl reacts with Ph₂PSiMe₃ in the presence of tertiary Phosphines (PⁿBu₂^tBu, PMeⁿPr₂, PⁿPr₃ and PEt₃) to form the multinuclear complexes [Ag₃(PPh₂)₃(PⁿBu₂^tBu)₃] 1 , [Ag₄(PPh₂)₄(PR₃)₄] (PR₃ = PMeⁿPr₂ 2 , PⁿPr₃ 3 ) and [Ag₄(PPh₂)₄(PEt₃)₄]_n 4 . In analogy to that ZnCl₂ reacts with Ph₂PSiMe₃ and PRR′₂ to form the multinuclear complexes [Zn₄(PPh₂)₄Cl₄(PRR′₂)₂] (PRR′₂ = PMeⁿPr₂ 5 , PⁿBu₃ 6 , PEt₂Ph 7 ). Further it was possible to obtain the compounds [Zn₄(PhPSiMe₃)₄Cl₄(C₄H₈O)₂] 8 and [Zn₄(P^tBu₂)₄Cl₄] 9 by reaction of ZnCl₂ with PhP(SiMe₃)₂ and ^tBu₂PSiMe₃, respectively. The structures were characterized by X-ray single crystal structure analysis. Crystallographic data see “Inhaltsübersicht”.     

Reactions of Beryllium Halides in Liquid Ammonia: The Tetraammineberyllium Cation [Be(NH3)4]2+, its Hydrolysis Products,and the Action of Be2+ as a Fluoride‐Ion Acceptor

The first structural characterization of the text‐book tetraammineberyllium(II) cation [Be(NH₃)₄]²⁺, obtained in the compounds [Be(NH₃)₄]₂Cl₄ ? 17NH₃ and [Be(NH₃)₄]Cl₂, is reported. Through NMR spectroscopic and quantum chemical studies, its hydrolysis products in liquid ammonia were identified. These are the dinuclear [Be₂(μ‐OH)(NH₃)₆]³⁺ and the cyclic [Be₂(μ‐OH)₂(NH₃)₄]²⁺ and [Be₃(μ‐OH)₃(NH₃)₆]³⁺ cations. The latter species was isolated as the compound [Be₃(μ‐OH)₃(NH₃)₆]Cl₃ ? 7NH₃. NMR analysis of solutions of BeF₂ in liquid ammonia showed that the [BeF₂(NH₃)₂] molecule was the only dissolved species. It acts as a strong fluoride‐ion acceptor and forms the [BeF₃(NH₃)]^? anion in the compound [N₂H₇][BeF₃(NH₃)]. The compounds presented herein were characterized by single‐crystal X‐ray structure analysis, ⁹Be, ¹⁷O, and ¹⁹F NMR, IR, and Raman spectroscopy, deuteration studies, and quantum chemical calculations. The extension of beryllium chemistry to the ammine system shows similarities but also decisive differences to the aquo system.     

[Be3(μ3‐O)3(MeCN)6{Be(MeCN)3}3](I)6 – ein Berylliumkomplex mit Cyclo‐(Be3O3)‐Kern und sein Hydrolyseprodukt [Be(H2O)4](I)2·2MeCN

Single crystals of [Be₃(μ₃‐O)₃(MeCN)₆{Be(MeCN)₃}₃](I)₆·4CH₃CN ( 1 ·4CH₃CN) were obtained in low yield by the reaction of beryllium powder with iodine in acetonitrile suspension, which probably result from traces of beryllium oxide containing the applied beryllium metal. The compound 1 ·4CH₃CN forms moisture sensitive, colourless crystal needles, which were characterized by IR spectroscopy and X‐ray diffraction (Space group Pnma, Z = 4, lattice dimensions at 100(2) K: a = 2317.4(1), b = 2491.4(1), c = 1190.6(1) pm, R₁ = 0.0315). The hexaiodide complex cation 1 ⁶⁺consists of a cyclo‐Be₃O₃ core with slightly distorted chair conformation, stabilized by coordination of two acetonitrile ligands at each of the beryllium atoms and by a {Be(CH₃CN)₃}²⁺ cation at each of the oxygen atoms. This unique coordination behaviour results in coplanar OBe₃ units with short Be–O distances of 155.0 pm and 153.6 pm on average of bond lengths within the cyclo‐Be₃O₃ unit and of the peripheric BeO bonds, respectively. Exposure of compound 1 ·4CH₃CN to moist air leads to small orange crystal plates of [Be(H₂O)₄]I₂·2CH₃CN ( 3 ·2CH₃CN). According to the crystal structure determination (Space group C2/c, Z = 4, lattice dimensions at 100(2) K: a = 1220.7(1), b = 735.0(1), c = 1608.5(1) pm, β = 97.97(1)°, R₁ = 0.0394), all hydrogen atoms of the dication [Be(H₂O)₄]²⁺ are involved to form O–H ··· N and O–H ··· I hydrogen bonds with the acetonitrile molecules and the iodide ions, respectively. Quantum chemical calculations (B3LYP/6‐311+G**) at the model [Be₃(μ₃‐O)₃(HCN)₆{Be(HCN)₃}₃]⁶⁺ show that chair and boat conformation are stable and that the distorted chair conformation is stabilized by packing effects.     

Über Reaktionen von Hexachlorodiberyllat mit Trimethylsilyl‐N‐dimethylamid. Die Kristallstrukturen von (Ph4P)3[Be2Cl5(OSiMe3)][BeCl3(Me2NSiMe3)], (Ph4P)[BeCl3(HNMe2)] und (Ph4P)(H2NMe2)[BeCl4]

On Reactions of Hexachlorodiberyllate with Trimethylsilyl‐N‐dimethylamide. Crystal Structures of (Ph₄P)₃[Be₂Cl₅(OSiMe₃)][BeCl₃(Me₂NSiMe₃)], (Ph₄P)[BeCl₃(HNMe₂)], and (Ph₄P)(H₂NMe₂)[BeCl₄] Reactions of bis‐tetraphenylphosphonium hexachlorodiberyllate, (Ph₄P)₂[Be₂Cl₆], with trimethylsilyl‐N‐dimethylamide under different conditions lead to the novel chloroberyllate derivatives (Ph₄P)₃[Be₂Cl₅(OSiMe₃)][BeCl₃(Me₂NSiMe₃)] ( 1 ), (Ph₄P)[BeCl₃(HNMe₂)] ( 2 ), and (Ph₄P)(H₂NMe₂)[BeCl₄] ( 3 ). 1 ‐ 3 were characterized by IR spectroscopy and crystal structure determinations. 1· 4CH₂Cl₂: Space group P1¯, Z = 2, lattice dimensions at 193 K: a = 1115.6(1), b = 2110.7(2), c = 2145.0(3) pm, α = 71.38(1)°, β = 85.66(1)°, γ = 85.24(1)°, R₁ = 0.0732. The [Be₂Cl₅(OSiMe₃)]^2— ion in the structure of 1 is derived from the [Be₂Cl₆]^2— ion by substitution of a μ‐Cl ligand by the oxygen atom of the (OSiMe₃)^— group. The second anion, [BeCl₃(Me₂NSiMe₃)]^—, can be described as donor acceptor complex with a short Be—N bond of 179(1) pm. 2 : Space group P1¯, Z = 2, lattice dimensions at 193 K: a = 1063.1(1), b = 1072.0(1), c = 1238.3(1) pm, α = 87.55(1)°, β = 74.86(1)°, γ = 69.73(1)°, R₁ = 0.0299. The anion of 2 forms a centrosymmetric dimer [BeCl₃(HNMe₂)]₂^2— via N—H···Cl bridges of the two donor acceptor complex units with Be—N separations of 175.2(2) pm. 3 : Space group Pbca, Z = 8, lattice dimensions at 193 K: a = 926.9(1), b = 2164.7(1), c = 2732.7(1) pm, R₁ = 0.0495. The structure of 3 contains centrosymmetric ion quadrupoles [(Me₂NH₂)(BeCl₄)]₂^2— forming by N—H···Cl bridges between (Me₂NH₂)⁺ and [BeCl₄]^2— ions.     

Chloroberyllate mit Stickstoff‐Donorliganden. Die Kristallstrukturen von (Ph4P)[BeCl3(Py)], (Ph4P)2[(BeCl3)2(TMEDA)], (Ph4P)[BeCl2{(Me3SiN)2CPh}] und (Ph4P)2[BeCl4] · 2CH2Cl2

Chloroberyllates with Nitrogen Donor Ligands. Crystal Structures of (Ph₄P)[BeCl₃(py)], (Ph₄P)₂[(BeCl₃)₂(tmeda)], (Ph₄P)[BeCl₂{(Me₃SiN)₂CPh}], and (Ph₄P)₂[BeCl₄] · 2CH₂Cl₂ The title compounds were obtained as colourless, moisture sensitive crystals by reactions of (Ph₄P)₂[Be₂Cl₆] with pyridine, tmeda (N, N′‐tetramethylethylendiamine), or with the silylated benzamidine PhC—[N(SiMe₃)₂(NSiMe₃)], whereas the tetrachloro beryllate was isolated as a by‐product from a solution in dichloromethane in the presence of the silylated phosphaneimine Me₃SiNP(tol)₃. All compounds were characterized by crystal structure determinations and by IR spectroscopy. (Ph₄P)[BeCl₃(Py)] ( 1 ): Space group Pbcm, Z = 4, lattice dimensions at 193 K: a = 756.2(1), b = 1739.2(2), c = 2016.3(2) pm, R₁ = 0.0626. The complex anion contains tetrahedrally coordinated beryllium atom with a Be—N distance of 176.5 pm. (Ph₄P)₂[(BeCl₃)₂(tmeda)]·2CH₂Cl₂ ( 2 ·2CH₂Cl₂). Space group P1¯, Z = 1, lattice dimensions at 193 K: a = 1072.7(1), b = 1132.6(1), c = 1248.9(1) pm, α = 95.34(1)°, β = 92.80(1)°, γ = 90.81(1)°, R₁ = 0.0344. Both nitrogen atoms of the tmeda molecule coordinate with BeCl₃^— units forming the centrosymmetric complex anion with Be—N distances of 181.3 pm. (PPh₄)[BeCl₂{(Me₃SiN)₂CPh}] ( 3 ). Space group C2, Z = 2, lattice dimensions at 193 K: a = 1255.4(2), b = 1401.9(2), c = 1085.2(2) pm, R₁ = 0.0288. In the complex anion the benzamidinato ligand {(Me₃SiN)₂CPh}^— acts as chelate with Be—N distances of 174.9 pm. (Ph₄P)₂[BeCl₄]·2CH₂Cl₂ ( 4 ·2CH₂Cl₂). Space group P2/c, Z = 4, lattice dimensions at 193 K: a = 2295.4(1), b = 982.5(1), c = 2197.2(2) pm, β = 99.19(1)°, R₁ = 0.0586. 4 ·2CH₂Cl₂ contains nearly ideal tetrahedral [BeCl₄]^2— ions, like the previously described 4 ·2, 5CH₂Cl₂, which crystallizes in the space group P1¯, with Be—Cl distances of 203.4 pm on average.     

Li+ cation coordination in [Li2(CF3SO3)2(diglyme)] and [Li3(C2F3O2)3(diglyme)]

The title compounds, poly­[[[bis(2‐methoxy­ethyl) ether]­lithium(I)]‐di‐μ₃‐tri­fluoro­methanesulfonato‐lithium(I)], [Li₂(CF₃SO₃)₂(C₆H₁₄O₃)]_n, and poly­[[[bis(2‐methoxy­ethyl) ether]­lithium(I)]‐di‐μ₃‐tri­fluoro­acetato‐dilithium(I)‐μ₃‐tri­fluoro­acetato], [Li₃(C₂F₃O₂)₃(C₆H₁₄O₃)]_n, consist of one‐dimensional polymer chains. Both structures contain five‐coordinate Li⁺ cations coordinated by a tridentate diglyme [bis(2‐methoxy­ethyl) ether] mol­ecule and two O atoms, each from separate anions. In both structures, the [Li(diglyme)X₂]^? (X is CF₃SO₃ or CF₃CO₂) fragments are further connected by other Li⁺ cations and anions, creating one‐dimensional chains. These connecting Li⁺ cations are coordinated by four separate anions in both compounds. The CF₃SO₃^? and CF₃CO₂^? anions, however, adopt different forms of cation coordination, resulting in differences in the connectivity of the structures and solvate stoichiometries.     

Unusual Structure,Fluxionality, and Reaction Mechanism of Carbonyl Hydrosilylation by Silyl Hydride Complex [(ArN)Mo(H)(SiH2Ph)(PMe3)3]

The reactions of bis(borohydride) complexes [(RN?)Mo(BH₄)₂(PMe₃)₂] ( 4 : R=2,6‐Me₂C₆H₃; 5 : R=2,6‐iPr₂C₆H₃) with hydrosilanes afford new silyl hydride derivatives [(RN?)Mo(H)(SiR′₃)(PMe₃)₃] ( 3 : R=Ar, R′₃=H₂Ph; 8 : R=Ar′, R′₃=H₂Ph; 9 : R=Ar, R′₃=(OEt)₃; 10 : R=Ar, R′₃=HMePh). These compounds can also be conveniently prepared by reacting [(RN?)Mo(H)(Cl)(PMe₃)₃] with one equivalent of LiBH₄ in the presence of a silane. Complex 3 undergoes intramolecular and intermolecular phosphine exchange, as well as exchange between the silyl ligand and the free silane. Kinetic and DFT studies show that the intermolecular phosphine exchange occurs through the predissociation of a PMe₃ group, which, surprisingly, is facilitated by the silane. The intramolecular exchange proceeds through a new non‐Bailar‐twist pathway. The silyl/silane exchange proceeds through an unusual Mo^VI intermediate, [(ArN?)Mo(H)₂(SiH₂Ph)₂(PMe₃)₂] ( 19 ). Complex 3 was found to be the catalyst of a variety of hydrosilylation reactions of carbonyl compounds (aldehydes and ketones) and nitriles, as well as of silane alcoholysis. Stoichiometric mechanistic studies of the hydrosilylation of acetone, supported by DFT calculations, suggest the operation of an unexpected mechanism, in that the silyl ligand of compound 3 plays an unusual role as a spectator ligand. The addition of acetone to compound 3 leads to the formation of [trans‐(ArN)Mo(OiPr)(SiH₂Ph)(PMe₃)₂] ( 18 ). This latter species does not undergo the elimination of a Si? O group (which corresponds to the conventional Ojima′s mechanism of hydrosilylation). Rather, complex 18 undergoes unusual reversible β‐CH activation of the isopropoxy ligand. In the hydrosilylation of benzaldehyde, the reaction proceeds through the formation of a new intermediate bis(benzaldehyde) adduct, [(ArN?)Mo(η²‐PhC(O)H)₂(PMe₃)], which reacts further with hydrosilane through a η¹‐silane complex, as studied by DFT calculations.     

Unsaturated Ruthenium Hydrides as Reactive Intermediates: An Experimental Investigation and Theoretical Model Study of (dtbpm‐κ2P)Ru(H)Cl, (dtbpe‐κ2P)Ru(H)Cl and Their Dinuclear Dynamic Precursor Complexes

A detailed spectroscopic and quantum‐chemical structure investigation of the dinuclear, 16‐valence‐electron complexes [(^tBu₂P(CH₂)_nP^tBu₂‐κ²P)RuH]₂(μ₂‐Cl)₂ (n=1, 2), stabilized by the bulky, electron‐rich chelating ligands bis[di(t‐butyl)phosphano]methane (^tBu₂PCH₂P^tBu₂, dtbpm) and 1,2‐bis[di(t‐butyl)phosphano]ethane (^tBu₂PCH₂CH₂P^tBu₂, dtbpe) is reported. VT‐NMR Spectroscopy of [(dtbpm‐κ²P)RuH]₂(μ₂‐Cl)₂, an important precursor of olefin metathesis catalysts, and of its homologue [(dtbpe‐κ²P)RuH]₂(μ₂‐Cl)₂ reveals facile interconversion of dinuclear cis‐ and trans‐dihydride isomers for both systems. Crossover experiments provide evidence for the existence of short‐lived, mononuclear intermediates (dtbpm‐κ²P)Ru(H)Cl and (dtbpe‐κ²P)Ru(H)Cl in solution. Mechanistic features of the cis‐trans isomerization process as well as structural and electronic properties of model systems for the dinuclear complexes and mononuclear intermediates were treated theoretically by DFT calculations.     

氮芥苯甲酸氧化二丁基锡复合物的合成、晶体结构及其体外抗癌活性研究

Di-n-butyltin oxide reacted with p-[N,N-bis（2-chloroethyl）amino]benzoic acid to yield the compounds {{4-[（ClCH2CH2）2N]C6H4COOSnBu2}2O}2 （1） and {4-[（ClCH2CH2）2N]C6H4COO}2SnBu2 （2）, which have been characterized by IR and ^1H NMR spectra. The X-ray diffractional studies of 1 reveal the structure of the molecule to be a dimer, in which the two Bu2Sn groups were linked via two bridging oxygen atoms to form a central Bu4Sn2O2 unit. And the tin atom adopts two carbons from two n-butyl groups and three oxygen atoms from the acid and the bridging oxygen. In vitro test showed compound 1 to exhibit high cytotoxicity against P388 and HL-60 cell lines.     

Synthesen und NMR‐Untersuchungen von Salzen mit den neuen Anionen [PtXn(CF3)6‐n]2— (n = 0 ‐ 5, X = F,OH, Cl,CN) und die Kristallstrukturanalyse von K2[(CF3)2F2Pt(μ‐OH)2PtF2(CF3)2]·2H2O

Syntheses and NMR Spectroscopic Ivestigations of Salts containing the Novel Anions [PtX_n(CF₃)_6‐n]^2— (n = 0 ‐ 5, X = F, OH, Cl, CN) and Crystal Structure of K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O The first syntheses of trifluoromethyl‐complexes of platinum through fluorination of cyanoplatinates are reported. The fluorination of tetracyanoplatinates(II), K₂[Pt(CN)₄], and hexacyanoplatinates(IV), K₂[Pt(CN)₆], with ClF in anhydrous HF leads after working up of the products to K₂[(CF₃)₂F₂Pt(μ‐OH)₂PtF₂(CF₃)₂]·2H₂O. The structure of the salt is determined by a X‐ray structure analysis, P2₁/c (Nr. 14), a = 11.391(2), b = 11.565(2), c = 13.391(3)Å, β = 90.32(3)°, Z = 4, R₁ = 0.0326 (I > 2σ(I)). The reaction of [Bu₄N]₂[Pt(CN)₄] with ClF in CH₂Cl₂ generates mainly cis‐[Bu₄N]₂[PtCl₂(CF₃)₄] and fac‐[Bu₄N]₂[PtCl₃(CF₃)₃], but in contrast that of [Bu₄N]₂[Pt(CN)₆] with ClF in CH₂Cl₂ results cis‐[Bu₄N]₂[PtX₂(CF₃)₄], [Bu₄N]₂[PtX(CF₃)₅] (X = F, Cl) and [Bu₄N]₂[Pt(CF₃)₆]. In the products [Bu₄N]₂[PtX_n(CF₃)_6‐n] (X = F, Cl, n = 0—3) it is possibel to exchange the fluoro‐ligands into chloro‐ and cyano‐ligands by treatment with (CH₃)₃SiCl und (CH₃)₃SiCN at 50 °C. With continuing warming the trifluoromethyl‐ligands are exchanged by chloro‐ and cyano‐ligands, while as intermediates CF₂Cl and CF₂CN ligands are formed. The identity of the new trifluoromethyl‐platinates is proved by ¹⁹⁵Pt‐ and ¹⁹F‐NMR‐spectroscopy.     

From Very Strong to Inexistent Be−Be Bonds in the Interactions of Be2 with π-Systems

Isolated Be₂ is a typical example of a weakly bound system, but interaction with other systems may give rise to surprising bonding features. The interactions between Be₂ and a set of selected neutral C_nH_n (n=2–8) π-systems have been analyzed through the use of G4 and G4MP2 ab initio methods, along with multireference CASPT2//CASPT2 calculations. Our results systematically show that the C_nH_n−Be₂−C_nH_n clusters formed are always very stable. However, the nature of this interaction is completely different when the π-system involved is a closed shell species (n=2, 4, 6, 8), or a radical (n=3, 5, 7). In the first case, the interaction does not occur with the π-system as a whole, but with specific C centers yielding rather polar but strong C−Be bonds. Nonetheless, although the Be−Be distances in these complexes are similar to the ones in compounds with ultra-strong Be−Be bonds, a close examination of their electron density distribution reveals that no Be−Be bonds exist. The situation is totally different when the interaction involves two π-radicals, C_nH_n−Be₂−C_nH_n (n=3, 5, 7). In these cases, a strong Be−Be bond is formed. Indeed, even though Be is electron deficient, the Be₂ moiety behaves as an efficient electron donor towards the two π-radicals, so that the different C_nH_n−Be₂−C_nH_n (n=3, 5, 7) clusters are the result of the interaction between Be₂²⁺ and two L⁻ anions. The characteristics of these two scenarios do not change when dealing with bicyclic π-compounds, such as naphthalene and pentalene, because the interaction with the Be₂ moiety is localized on one of the unsaturated cycles, the other being almost a spectator.     

Gasförmige BeCl2/AICl3-Komplexe

Gaseous BeCl₂/AlCl₃ complexes During the volatilization of the chlorides of beryllium and aluminium the complex molecules BeAlCl₅, Be₂AlCl₇, BeAl₂Cl₈, Be₂Al₂Cl₁₀, and (in a very small concentration) Be₃Al₂Cl₁₂ have been observed by means of a mass spectrometer. The structure of the compounds is discussed.     

Die Reaktion von tBu2P‐P=P(Me)tBu2 mit [Fe2(CO)9] und [(η2‐C8H14)2Fe(CO)3]

^tBu₂P‐P=P(Me)^tBu₂ reacts with [Fe₂(CO)₉] to give [μ‐(1, 2, 3:4‐η‐^tBu₂P¹‐P²‐P³‐P^4tBu₂){Fe(CO)₃}{Fe(CO)₄}] ( 1 ) and [trans‐(^tBu₂MeP)₂Fe(CO)₃]( 2 ). With [(η²‐C₈H₁₄)₂Fe(CO)₃] in addition to [μ‐(1, 2, 3:4‐η‐^tBu₂P¹‐P²‐P³‐P^4tBu₂){Fe(CO)₂PMe^tBu₂}‐{Fe(CO)₄}] ( 10 ) and 2 also [(μ‐P^tBu₂){μ‐P‐Fe(CO)₃‐PMe^tBu₂}‐{Fe(CO)₃}₂(Fe‐Fe)]( 9 ) is formed. 1 crystallizes in the monoclinic space group P2₁/c with a = 875.0(2), b = 1073.2(2), c = 3162.6(6) pm and β = 94.64(3)?. 2 crystallizes in the monoclinic space group P2₁/c with a = 1643.4(7), b = 1240.29(6), c = 2667.0(5) pm and β = 97.42(2)?. 9 crystallizes in the monoclinic space group P2₁/n with a = 1407.5(5), b = 1649.7(5), c = 1557.9(16) pm and β = 112.87(2)?.     

Zum Einfluß der PR3‐Liganden auf Bildung und Eigenschaften der Phosphinophosphiniden‐Komplexe [{η2‐tBu2P–P}Pt(PR3)2] und [{η2‐tBu2P1–P2}Pt(P3R3)(P4R′3)]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR₃ Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η²‐^tBu₂P–P}Pt(PR₃)₂] and [{η²‐^tBu₂P¹–P²}Pt(P³R₃)(P⁴R′₃)] (R₃P)₂PtCl₂ and C₂H₄ yield the compounds [{η²‐C₂H₄}Pt(PR₃)₂] (PR₃ = PMe₃, PEt₃, PPhEt₂, PPh₂Et, PPh₂Me, PPh₂ⁱPr, PPh₂^tBu and P(p‐Tol)₃); which react with ^tBu₂P–P=PMe^tBu₂ to give the phosphinophosphinidene complexes [{η²‐^tBu₂P–P}Pt(PMe₃)₂], [{η²‐^tBu₂P–P}Pt(PEt₃)₂], [{η²‐^tBu₂P–P}Pt(PPhEt₂)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Et)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Me)₂], [{η²‐^tBu₂P–P}Pt(PPh₂ⁱPr], [{η²‐^tBu₂P–P}Pt(PPh₂^tBu)₂] and [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂]. [{η²‐^tBu₂P–P}Pt(PPh₃)₂] reacts with PMe₃ and PEt₃ as well as with ^tBu₂PMe, PⁱPr₃ and P(c‐Hex)₃ by substituting one PPh₃ ligand to give [{η²‐^tBu₂P¹–P²}Pt(P³Me₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Ph₃)(P⁴Me₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Et₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³ⁱPr₃)(P⁴Ph₃)] and [{η²‐^tBu₂P¹–P²}Pt(P³(c‐Hex)₃)(P⁴Ph₃)]. With ^tBu₂PMe, [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂] forms [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴(p‐Tol)₃)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR₃ ligands.     

Neue Phosphido-verbrückte Mehrkernkomplexe des Ag,Cd und Zn Die Kristallstrukturen von [Ag4(PPh2)4(PMe3)4], [Ag6(PPh2)6(PtBu3)2] und [M4Cl4(PPh2)4(PnPr3)2] (M = Zn,Cd)

New Phosphido-bridged Multinuclear Complexes of Ag, Cd and Zn. The Crystal Structures of [Ag₄(PPh₂)₄(PMe₃)₄], [Ag₆(PPh₂)₆(P^tBu₃)₂] and [M₄Cl₄(PPh₂)₄(PⁿPr₃)₂] (M = Zn, Cd) AgCl reacts with Ph₂PSiMe₃ in the presence of a tertiary Phosphine PMe₃ or P^tBu₃ to form the multinuclear complexes [Ag₄(PPh₂)₄(PMe₃)₄] ( 1 ) and [Ag₆(PPh₂)₆(P^tBu₃)₂] ( 2 ). In analogy to that MCl₂ reacts with Ph₂PSiMe₃ in the presence of PⁿPr₃ to form the two multinuclear complexes [M₄Cl₄(PPh₂)₄(PⁿPr₃)₂] (M = Zn ( 3 ), Cd ( 4 )). The structures were characterized by X-ray single crystal structure analysis ( 1 : space group Pna2₁ (Nr. 33), Z = 4, a = 1 313.8(11) pm, b = 1 511.1(6) pm, c = 4 126.0(18) pm, 2 : space group P–1 (Nr. 2), Z = 2, a = 1 559.0(4) pm, b = 1 885.9(7) pm, c = 2 112.4(8) pm, α = 104.93(3)°, β = 94.48(3)°, γ = 104.41(3)°; 3 : space group C2/c (Nr. 15), Z = 4, a = 2 228.6(6) pm, b = 1 847.6(6) pm, c = 1 827.3(6) pm, β = 110.86(2); 4 : space group C2/c (Nr. 15), Z = 4, a = 1 894.2(9) pm, b = 1 867.9(7) pm, c = 2 264.8(6) pm, β = 111.77(3)°). 3 and 4 may be considered as intermediates on the route towards polymeric [M(PPh₂)₂]_n (M = Zn, Cd).     

Fragmentation of μ4-oxohexa-μ-nitratotetraberyllium, Be4O(NO)3)6, under electron impact

The behaviour of Be₄O(NO₃)₆ under electron impact is similar to that of its carboxylato analogues, Be₄O(RCO₂)₆ where R is H, alkyl or halogenated alkyl. In all these systems, the dissociation of the molecular ions is dominated by steric interactions. The major fragmentations involve the elimination of N₂O₅ or (RCO)₂O and Be(NO₃)₂ or Be(RCO₂)₂ from the ions [M-NO₃]⁺ or [M-RCO₂]⁺. The results obtained confirm the structural similarity of the nitrato complex to tetra-nuclear beryllium oxocarboxylates.     

Alternativ-Liganden. XXXII [1]. Neue Tetraphosphan-Nickelkomplexe mit Tripod-Liganden des Typs XM′ (OCH2PMe2)n(CH2CH2PR2)3 – n (M′ = Si,Ge; n = 0 – 3)

Alternative Ligands. XXXII [1]. Novel Tetraphosphane Nickel Complexes with Tripod-Ligands of the Type XM′(OCH₂PMe₂)_n(CH₂CH₂PR₂)_{3 – n} (M′ = Si, Ge; n = 0 – 3) Tripod Ligands of the type XM′(OCH₂PMe₂)_n(CH₂CH₂PMe_{23 – n} (M′ = Si, Ge; n = 0 – 3) ( 1 – 6 , Table 1) have been used together with PPh₃ or PMe₃ for the preparation of novel tetraphosphane complexes of Nickel. The representatives LNiPPh₃ ( 7 – 12 ) are obtained by reaction of Ni(COD)₂ (COD = 1,5-cyclooctadiene) with the corresponding ligands and PPh₃ in toluene in moderate yields. The synthesis of the derivatives LNiPMe₃ ( 13 – 18 ) is partly ( 16 – 18 ) accomplished in analogy to the Ph₃P-complexes; compounds 13 – 16 are obtained in higher yields by reaction of Ni(PMe₃)₄ with the respective ligand. As a rule, 13 – 18 cannot be separated from by-products. The trinuclear complex FSi(CH₂CH₂PMe₂)₃[Ni(PMe₂CH₂CH₂)₃SiF]₃ ( 19 ) is formed together with 18 in the reaction of Ni(COD)₂ with 6 and PMe₃. The new compounds have been characterized (if possible) by analytical (C, H), but in general by spectroscopic investigations (IR; ¹H-, ¹³C-, ¹⁹F-, ³¹P-NMR; MS). A weak, but significant Ni → Si interaction through the cage is indicated by the following results: (i) Large low-field shifts δδ_F of 35.2 ppm ( 12 ), 38.3 ppm ( 18 ) and 37.7 ppm ( 19 ); (ii) ⁶J(PF) coupling constants [or ³J(PNiSiF) through the cage] of 6.0 Hz ( 12 ) and 7.6 Hz ( 18 ) together with a low-field shift δδ_Si of 12.8 ppm ( 12 ); (iii) NiSi distances of 3.95 Å in 7 and 3.92 Å in 12 , accompanied by a compression of the cage along the Ni ··· Si axis. An additional release from the high charge density on Ni results from π-backbonding to the phosphane ligands.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXII. Die Bildung von [η2‐{tBu–P=P–SiMe3}Pt(PR3)2]aus (Me3Si)tBuP–P=P(Me)tBu2 und [η2‐{C2H4}Pt(PR3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXII. The Formation of [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂] from (Me₃Si)^tBuP–P=P(Me)^tBu₂ and [η²‐{C₂H₄}Pt(PR₃)₂] (Me₃Si)^tBuP–P = P(Me)^tBu₂ reacts with [η²‐{C₂H₄}Pt(PR₃)₂] yielding [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂]. However, there is no indication for an isomer which would be the analogue to the well known [η²‐{^tBu₂P–P}Pt(PPh₃)₂]. The syntheses and NMR data of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] and [η²‐{^tBu–P=P–SiMe₃}Pt(PMe₃)₂] as well as the results of the single crystal structure determination of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] are reported.