New Insights in Asymmetric Tetraorganodistannoxane Ladder Formation. A NMR‐Spectroscopic and Crystallographic study

The syntheses of the asymmetrically substituted tetraorganodistannoxanes [t‐Bu₂(X)SnOSn(Y)(CH₂SiMe₃)₂]₂ ( 1 , X = Y = OH; 2 , X = Cl, Y = OH; 3 , X = Y = Cl) are reported and their structures in solution and in the solid state are characterized by multinuclear NMR spectroscopy and single crystal X‐ray analyses. In toluene, the tetrahydroxy‐substituted derivative 1 is in equilibrium with the organotin oxides cyclo‐[t‐Bu₂Sn{OSn(CH₂SiMe₃)₂}₂O] ( 4 ), cyclo[(Me₃SiCH₂)₂Sn(OSnt‐Bu₂)₂O] ( 5 ), and cyclo‐(t‐Bu₂SnO)₃, and some additional, undefined species containing pentacoordinated tin atoms. In contrast, the dihydroxydichloro‐substituted derivative 2 is inert in solution.     

Synthetic and Structural Studies on the Cyclic Bis(amino)stannylenes Sn[(NR)2C10H6‐1, 8] and their Reactions with SnCl2 or Si[(NCH2But)2C6H4‐1, 2] (R = SiMe3 or CH2But)

Treatment of {HNR}₂C₁₀H₆‐1, 8 [R = SiMe₃ ( 1 ), CH₂Bu^t ( 2 )] with Sn[N(SiMe₃)₂]₂ afforded the cyclic stannylene Sn[{NR}₂C₁₀H₆‐1, 8] [R = SiMe₃ ( 3 ), CH₂Bu^t ( 4 )]. From 3 and SnCl₂ in THF and crystallisation from toluene, the product was the crystalline tetracyclic compound ( 5 ) as the (toluene)_0.5‐solvate. Reaction of 4 with the silylene Si[(NCH₂Bu^t)₂C₆H₄‐1, 2] ( 6 ) [abbreviated as Si(NN)] in benzene and crystallisation in presence of Et₂O furnished the crystalline tricyclic complex Sn[{Si(NCH₂Bu^t)₂C₆H₄‐1′, 2′}₂‐{(NCH₂Bu^t)₂C₁₀H₆‐1, 8}] ( 7 ) as the Et₂O‐solvate. Complex 5 slowly dissociated into its factors 3 and SnCl₂ in toluene, but rapidly in THF. Solutions of 7 in C₆D₆, C₇D₈ or THF‐d₈, studied by multinuclear, variable temperature NMR spectroscopy, revealed the presence of an equilibrium between 8 (an isomer of 7 , in which the skeletal atoms of the eight‐membered ring were , rather than the of 7 ) and 4 + 2 Si(NN), with 8 dominant in PhMe but not in THF; additionally 8 was shown to be fluxional and solutions of 8 in C₆D₆ or C₇D₈ decomposed to give the silane Si(NN)[(NCH₂Bu^t)₂C₁₀H₆‐1, 8], 6 and Sn metal. The X‐ray structures of 3 , 5 and 7 are presented.     

Multi‐Pyrene Assemblies Supported on Stannoxane Frameworks: Synthesis,Structure and Photophysical Studies

Organostannoxanes have been used as scaffolds for the preparation of multi‐chromophore assemblies. A single‐step synthesis procedure allows the preparation of compounds in which the number of chromophore units can be varied from two to six. Thus, the reactions of pyrene sulfonic acid (PySO₃H) or C₁₆H₉CHNC₆H₃(COOH)₂ (LH₂) with various organotin precursors gave pyrene‐containing organostannoxanes, that is, [Ph₃SnPySO₃]₆ ( 1 ), [{(Me₂Sn)₂(μ₃‐O)(μ‐OH)PySO₃}₂{(Me₂Sn)₂(μ₃‐O)(μ‐OH)H₂O}₂ ? 2 PySO₃] ( 2 ), [{tBu₂Sn(OH)PySO₃}₂] ( 3 ), [{(nBuSn)₁₂(O)₁₄(OH)₆{PySO₃}₂] ( 4 ), and [{(nBu₂Sn)L}₃]₂ ? C₆H₅CH₃ ( 5 ). Compounds 1 – 5 were characterized by using X‐ray crystallography. Compounds 1 and 5 are 24‐membered macrocycles. Macrocycle 1 possesses intramolecular π–π stacking interactions. An unusual co‐crystal of two tetrameric ladders in 2 was observed in which one of the components of the co‐crystal is neutral whereas the other is dicationic and two pyrenesulfonate counterions are present to balance the overall charge. In the solid state these compounds reveal rich supramolecular structures. Photophysical studies on 1 – 5 reveal that interactions in the solid state lead to considerable broadening of the emission bands.     

Darstellung und Kristallstrukturen von tBu‐substituierten Disiloxanen des Typus tBu2SiX‐O‐SiYtBu2 (X = Y = OH,Br; X = OH,Y = H) und den Addukten tBu3SiOH·(HO3SCF3)0.5·H2O und tBu3SiOLi·(LiO3SCF3)2·(H2O)2

Syntheses and Crystal Structures of tBu‐substituted Disiloxanes tBu₂SiX‐O‐SiYtBu₂ (X = Y = OH, Br; X = OH, Y = H) and of the Adducts tBu₃SiOH·(HO₃SCF₃)_0.5·H₂O and tBu₃SiOLi·(LiO₃SCF₃)₂·(H₂O)₂ The disiloxanes tBu₂SiX‐O‐SiYtBu₂ (X = Y = H, OH) are accessible from the reaction of CF₃SO₂Cl with tBu₂SiHOH or tBu₂Si(OH)₂. By this reaction the disiloxane tBu₂SiH‐O‐SiHtBu₂ is formed together with tBu₂SiH‐O‐SiOHtBu₂. The disiloxanes tBu₂SiX‐O‐SiYtBu₂ (X = Y = Cl, Br) can be synthesized almost quantitatively from tBu₂SiH‐O‐SiHtBu₂ with Cl₂ and Br₂ in CH₂Cl₂. The structures of the disiloxanes tBu₂SiX‐O‐SiYtBu₂ (X = H, Y = OH; X = Y = OH, Br) show almost linear Si‐O‐Si units with short Si‐O bonds. Single crystals of the adducts tBu₃SiOH·(HO₃SCF₃)_0.5·H₂O and tBu₃SiOLi·(LiO₃SCF₃)₂·(H₂O)₂ have been obtained from the reaction of tBu₃SiOH with CF₃SO₃H and of tBu₃SiO₃SCF₃ with LiOH. According to the result of the X‐ray structural analysis (hexagonal, P‐62c), tBu₃SiOLi · (LiO₃SCF₃)₂·(H₂O)₂ features the ion pair [(tBu₃SiOLi)₂(LiO₃SCF₃)₃(H₂O)₃Li]⁺ [CF₃SO₃]^?. The central framework of the cation forms a trigonal Li₆ prism.     

A Sterically Hindered Phosphonic Acid with a Hydrogen‐Bonded Cage Structure: [4‐tert‐Bu‐2,6‐Mes2‐C6H2P(O)(OH)2·H2O]4

The synthesis and molecular structure of the novel phosphonic acid 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂P(O)(OH)₂ ( 1 ) is reported. Compound 1 crystallizes in form of its monohydrate as a hydrogen‐bonded cluster ( 1·H₂O )₄ comprizing four phosphonic acid molecules (O···O 2.383(3)‐3.006(4) Å). Additionally, sterically hindered terphenyl‐substituted phosphorus compounds of the type 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PR(O)(OH) ( 5 , R = H; 7 , R = O₂CC₆H₄‐3‐Cl; 9 , R = OEt) were prepared, which all show dimeric hydrogen‐bonded structures with O···O distances in the range 2.489(2)–2.519(3) Å. Attempts at oxidizing 5 using H₂O₂, KMnO₄, O₃, or Me₃NO in order to give 1 failed. Crystallization of 5 in the presence of Me₃NO gave the novel hydrogen bonded aggregate 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PH(O)(OH)·ONMe₃ ( 6 ) showing an O–H···O distance of 2.560(4) Å.     

Nitric Oxide Insertion Reactivity with the Bismuth–Carbon Bond: Formation of the Oximate Anion, [ON(C6H2tBu2O)]−, from the Oxyaryl Dianion, (C6H2tBu2O)2−

The first example of NO insertion into a Bi?C bond has been found in the direct reaction of NO with a Bi³⁺ complex of the unusual (C₆H₂tBu₂‐3,5‐O‐4)^2? oxyaryl dianionic ligand, namely, Ar′Bi(C₆H₂tBu₂‐3,5‐O‐4) [Ar′=2,6‐(Me₂NCH₂)₂C₆H₃] ( 1 ). The oximate complexes [Ar′Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O)]₂(μ‐O) ( 3 ) and Ar′Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O)₂ ( 4 ) were formed as a mixture, but can be isolated in pure form by reaction of NO with a Bi³⁺ complex of the [O₂C(C₆H₂tBu₂‐3‐5‐O‐4]^2? oxyarylcarboxy dianion, namely, Ar′Bi[O₂C(C₆H₂tBu₂‐3‐5‐O‐4)‐κ²O,O’]. Reaction of 1 with Ph₃CSNO gave an oximate product with (Ph₃CS)^1? as an ancillary ligand, (Ph₃CS)(Ar′)Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O) ( 5 ).     

Ansa‐Complexes of [Mn(η5‐C5H5)(η6‐C6H6)]: Preparation,Characterization, and Reactivity of [n]Manganoarenophanes (n=1, 2, 3)

We report the synthesis of [n]manganoarenophanes (n=1, 2) featuring boron, silicon, germanium, and tin as ansa‐bridging elements. Their preparation was achieved by salt‐elimination reactions of the dilithiated precursor [Mn(η⁵‐C₅H₄Li)(η⁶‐C₆H₅Li)]?pmdta (pmdta=N,N,N′,N′,N′′‐pentamethyldiethylenetriamine) with corresponding element dichlorides. Besides characterization by multinuclear NMR spectroscopy and elemental analysis, the identity of two single‐atom‐bridged derivatives, [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] and [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SiPh₂], could also be determined by X‐ray structural analysis. We investigated for the first time the reactivity of these ansa‐cyclopentadienyl–benzene manganese compounds. The reaction of the distannyl‐bridged complex [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)Sn₂tBu₄] with elemental sulfur was shown to proceed through the expected oxidative addition of the Sn?Sn bond to give a triatomic ansa‐bridge. The investigation of the ring‐opening polymerization (ROP) capability of [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] with [Pt(PEt₃)₃] showed that an unexpected, unselective insertion into the C_ipso?Sn bonds of [Mn(η⁵‐C₅H₄)(η⁶‐C₆H₅)SntBu₂] had occurred.     

Ein ungewöhnlicher ambivalenter Zinn(II)‐oxo‐Cluster

An Unusual Ambivalent Tin(II)‐oxo Cluster The reaction of the copper aryl CuDmp (Dmp = 2, 6‐Mes₂C₆H₃; Mes = 2, 4, 6‐Me₃C₆H₂) with the stannanediyl Sn{1, 2‐(tBuCH₂N)₂C₆H₄} followed by hydrolysis affords in the presence of lithium‐tert‐butoxide the tin(II)‐oxo cluster {(Et₂O)(LiOtBu)(SnO)(CuDmp)}₂ ( 5 ) in small yield. The solid state structure of the colorless compound shows a central Li₂Sn₂O₂(OtBu)₂ fragment with heterocubane structure. In addition, the Li‐acceptor and O(Sn)‐donor atoms are used for the coordination of one molecule diethylether and copper aryl CuDmp, respectively.     

Synthesis and reactivity of alkynyl-linked phosphonium borates

The phosphine tBu₂PC?CH ( 1 ) was reacted with B(C₆F₅) to give the zwitterionic species tBu₂P(H)C?CB(C₆F₅)₃ ( 2 ). The analogous species tBu₂P(Me)C?CB(C₆F₅)₃ ( 3 ), tBu₂P(H)C?CB(Cl)(C₆F₅)₂ ( 4 ), tBu₂P(H)C?CB(H)(C₆F₅)₂ ( 5 ), and tBu₂P(Me)C?CB(H)(C₆F₅) ₂ ( 6 ) were also prepared. The salt [tBu₂P(H)C?CB(C₆F₅)₂(THF)][B(C₆F₅)₄] ( 7 ) was prepared through abstraction of hydride by [Ph₃C][B(C₆F₅)₄]. Species 5 reacted with the imine tBuN?CHPh to give the borane–amine adduct tBu₂PC?CB[tBuN(H)CH₂Ph](C₆F₅)₂ ( 8 ). The related phosphine Mes₂PC?CH ( 9 ; Mes=C₆H₂Me₃) was used to prepare [tBu₃PH][Mes₂PC?CB(C₆F₅)₃] ( 10 ) and generate Mes₂PC?CB(C₆F₅)₂. The adduct Mes₂PC?CB(NCMe)(C₆F₅)₂ ( 11 ) was isolated. Reaction of Mes₂PC?CB(C₆F₅)₂ with H₂ gave the zwitterionic product (C₆F₅)₂(H)BC(H)?C[P(H)Mes₂][(C₆F₅)₂BC?CP(H)Mes₂] ( 12 ). Reaction of tBu₂PC?CB(C₆F₅)₂, a phosphine–borane generated in situ from 5 , with 1‐hexene gave the species [tBu₂PC?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂] ( 13 ) and subsequent reaction with methanol or hexene resulted in the formation of [tBu₂P(H)C?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂](OMe) ( 14 ) or the macrocycle {[tBu₂PC?CB(C₆F₅)₂](CH₂CH₂nBu)}₂ ( 15 ), respectively. In a related fashion, the reaction of 13 with THF afforded the macrocycle [tBu₂PC?CB(C₆F₅)₂](CH₂CHnBu)[tBu₂PC?CB(C₆F₅)₂][O(CH₂)₄] ( 16 ), although treatment of tBu₂PC?CB(C₆F₅)₂ with THF lead to the formation of {[tBu₂PC?CB(C₆F₅)₂][O(CH₂)₄]}₂ ( 17 ). In a related example, the reaction of Mes₂PC?CB(C₆F₅)₂ with PhC?CH gave {[Mes₂PC?CB(C₆F₅)₂](CH?CPh)}₂ ( 18 ). Compound 5 reacted with AlX₃ (X=Cl, Br) to give addition to the alkynyl unit, affording (C₆F₅)₂BC(H)?C[P(H)tBu₂](AlX₃) (X=Cl 19 , Br 20 ). In a similar fashion, 5 reacted with [Zn(C₆F₅)₂] ? C₇H₈, [Al(C₆F₅)₃] ? C₇H₈, or HB(C₆F₅)₂ to give (C₆F₅)₃BC(H)?C[P(H)tBu₂][Zn(C₆F₅)] ( 21 ), (C₆F₅)₃BC(H)?C[P(H)tBu₂][Al(C₆F₅)₂] ( 22 ), or [(C₆F₅)₂B]₂HC?CH[P(H)tBu₂] ( 23 ), respectively. The implications of this reactivity are discussed.     

Synthesis and Molecular Structure of [n‐Bu2(F)SnOSn(F)t‐Bu2]2 — an Unsymmetrically Substituted Tetraorganodistannoxane

The dimeric tetraorganodistannoxane [n‐Bu₂(F)SnOSn(F)t‐Bu₂]₂ ( 1 ) was prepared by the reaction of (t‐Bu₂SnO)₃ with n‐Bu₂SnF₂ and characterized in solution by multinuclear NMR spectroscopy and ESI MS spectrometry and in the solid state by ¹¹⁹Sn MAS NMR spectroscopy and single crystal X‐ray diffraction.     

Synthesis,Spectroscopy, and Hydroformylation Activity of Sterically Demanding,Phosphite‐Modified Cobalt Catalysts

The dinuclear complex [Co₂(CO)₆{P(O‐2,4‐t‐Bu₂C₆H₃)₃}₂] ( 6 ) has been synthesised and fully characterised. X‐Ray crystal‐structure analysis revealed a trans‐diaxial geometry, no bridging carbonyls, and Co? Co and Co? P bond lengths of 2.706(5) and 2.134(4) Å, respectively. The hydroformylation of pent‐1‐ene in the presence of 6 was studied at 120–180° at pressures between 20 and 80 bar Syngas. High‐pressure (HP) spectroscopy (IR, NMR) was used to detect potential hydride intermediates. HP‐IR Studies revealed the formation of [CoH(CO)₃{P(O‐2,4‐t‐Bu₂C₆H₃)₃}] ( 2 ) at ca. 105°, with no significant amount of [CoH(CO)₄] detectable. The intermediate 2 was synthesised and characterised. The formation of the undesired complex [CoH(CO)₂{P(O‐2,4‐t‐Bu₂C₆H₃)₃}₂] was completely suppressed due to the large cone angle of the sterically demanding phosphite.     

Cationic organotin cluster [t‐Bu2Sn(OH)(H2O)]22+2OTf−‐catalyzed one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in water

The cationic organotin cluster [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? is easy to prepare and stable in air. The catalytic activity of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? as a neutral organotin Lewis acid catalyst is probed through the one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles from aldehydes, hydroxylamine hydrochloride and sodium azide, and of 2,4,6‐triarylpyridines from aromatic aldehydes, substituted acetophenones and ammonium acetate. The reactions proceed well in the presence of 1 mol% of [t‐Bu₂Sn(OH)(H₂O)]₂²⁺2OTf^? in water and provide the corresponding 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in good to excellent yields. The method reported has several advantages such as the catalyst being neutral, low catalyst loading and use of water as a green solvent.     

Dilithium Hexaorganostannate(IV) Compounds

Hypercoordination of main‐group elements such as the heavier Group 14 elements (silicon, germanium, tin, and lead) usually requires strong electron‐withdrawing ligands and/or donating groups. Herein, we present the synthesis and characterization of two hexaaryltin(IV) dianions in form of their dilithium salts [Li₂(thf)₂{Sn(2‐py^Me)₆}] (py^Me=C₅H₃N‐5‐Me) ( 2 ) and [Li₂{Sn(2‐py^OtBu)₆}] (py^OtBu=C₅H₃N‐6‐OtBu) ( 3 ). Both complexes are stable in the solid state and solution under inert conditions. Theoretical investigations of compound 2 reveal a significant valence 5s‐orbital contribution of the tin atom forming six strongly polarized tin–carbon bonds.     

Synthesis and Utility of Neptunium(III) Hydrocarbyl Complex

To extend organoactinide chemistry beyond uranium, reported here is the first structurally characterized transuranic hydrocarbyl complex, Np[η⁴‐Me₂NC(H)C₆H₅]₃ ( 1 ), from reaction of NpCl₄(DME)₂ with four equivalents of K[Me₂NC(H)C₆H₅]. Unlike the U^III species, the neptunium analogue can be used to access other Np^III complexes. The reaction of 1 with three equivalents of HE₂C(2,6‐Mes₂‐C₆H₃) (E=O, S) yields [(2,6‐Mes₂‐C₆H₃)CE₂]₃Np(THF)₂, maintaining the trivalent oxidation state.     

Chromium complexes bearing disubstituted organophosphate ligands and their use in ethylene polymerization

The crystal structures of three unusual chromium organophosphate complexes have been determined, namely, bis(μ‐butyl 2,6‐di‐tert‐butyl‐4‐methylphenyl hydrogen phosphato‐κO:κO′)di‐μ‐hydroxido‐bis[(butyl 2,6‐di‐tert‐butyl‐4‐methylphenyl hydrogen phosphato‐κO)(butyl 2,6‐di‐tert‐butyl‐4‐methylphenyl phosphato‐κO)chromium](Cr—Cr) heptane disolvate or {Cr₂(μ₂‐OH)₂[μ₂‐PO₂(OBu)(O‐2,6‐^tBu₂‐4‐MeC₆H₂)‐κO:κO′]₂[PO₂(OBu)(O‐2,6‐^tBu₂‐4‐MeC₆H₂)‐κO]₂[HOPO(OBu)(O‐2,6‐^tBu₂‐4‐MeC₆H₂)‐κO]₂}·2C₇H₁₆, [Cr₂(C₁₉H₃₂O₄P)₄(C₁₉H₃₃O₄P)₂(OH)₂]·2C₇H₁₆, denoted ( 1 )·2(heptane), [μ‐bis(2,6‐diisopropylphenyl) phosphato‐1κO:2κO′]bis[bis(2,6‐diisopropylphenyl) phosphato]‐1κO,2κO‐chlorido‐2κCl‐triethanol‐1κ²O,2κO‐di‐μ‐ethanolato‐1κ²O:2κ²O‐dichromium(Cr—Cr) ethanol monosolvate or {Cr₂(μ₂‐OEt)₂[μ₂‐PO₂(O‐2,6‐ⁱPr₂‐C₆H₃)₂‐κO:κO′][PO₂(O‐2,6‐ⁱPr₂‐C₆H₃)₂‐κO]₂Cl(EtOH)₃}·EtOH, [Cr₂(C₂H₅O)₂(C₂₄H₃₄O₄P)₃Cl(C₂H₆O)₃]·C₂H₆O, denoted ( 2 )·EtOH, and di‐μ‐ethanolato‐1κ²O:2κ²O‐bis{[bis(2,6‐diisopropylphenyl) hydrogen phosphato‐κO][bis(2,6‐diisopropylphenyl) phosphato‐κO]chlorido(ethanol‐κO)chromium}(Cr—Cr) benzene disolvate or {Cr₂(μ₂‐OEt)₂[PO₂(O‐2,6‐ⁱPr₂‐C₆H₃)₂‐κO]₂[HOPO(O‐2,6‐ⁱPr₂‐C₆H₃)₂‐κO]₂Cl₂(EtOH)₂}·2C₆H₆, [Cr₂(C₂H₅O)₂(C₂₄H₃₄O₄P)₂(C₂₄H₃₅O₄P)₂Cl₂(C₂H₆O)₂]·2C₆H₆, denoted ( 3 )·2C₆H₆. Complexes ( 1 )–( 3 ) have been synthesized by an exchange reaction between the in‐situ‐generated corresponding lithium or potassium disubstituted phosphates with CrCl₃(H₂O)₆ in ethanol. The subsequent crystallization of ( 1 ) from heptane, ( 2 ) from ethanol and ( 3 ) from an ethanol/benzene mixture allowed us to obtain crystals of ( 1 )·2(heptane), ( 2 )·EtOH and ( 3 )·2C₆H₆, whose structures have the monoclinic P2₁, orthorhombic P2₁2₁2₁ and triclinic P space groups, respectively. All three complexes have binuclear cores with a single Cr—Cr bond, i.e. Cr₂O₆P₂ in ( 1 ), Cr₂PO₄ in ( 2 ) and Cr₂O₂ in ( 3 ), where the Cr atoms are in distorted octahedral environments, formally having 16 ē per Cr atom. The complexes have bridging ligands μ₂‐OH in ( 1 ) or μ₂‐OEt in ( 2 ) and ( 3 ). The organophosphate ligands demonstrate terminal κO coordination modes in ( 1 )–( 3 ) and bridging μ₂‐κO:κO′ coordination modes in ( 1 ) and ( 2 ). All the complexes exhibit hydrogen bonding: two intramolecular O_phos…H—O_phos interactions in ( 1 ) and ( 3 ) form two {H[PO₂(OR)₂]₂} associates; two intramolecular Cl…H—O_Et hydrogen bonds additionally stabilize the Cr₂O₂ core in ( 3 ); two intramolecular O_phos…H—O_Et interactions and two O…H—O intermolecular hydrogen bonds with a noncoordinating ethanol molecule are observed in ( 2 )·EtOH. The presence of both basic ligands (OH^? or OEt^?) and acidic [H(phosphate)₂]^? associates at the same metal centres in ( 1 ) and ( 3 ) is rather unusual. Complexes may serve as precatalysts for ethylene polymerization under mild conditions, providing polyethylene with a small amount of short‐chain branching. The formation of a small amount of α‐olefins has been detected in this reaction.     

Dinuclear neodymium and lanthanum bis(2,6‐diisopropylphenyl) phosphate complexes bearing a hydroxide ligand: catalytic activity of the Nd complex in 1,3‐diene polymerization

The reactions of K[(2,6‐ⁱPr₂C₆H₃‐O)₂POO] either with LaCl₃(H₂O)₇ or with Nd(NO₃)₃(H₂O)₆ in a 3:1 molar ratio, followed by vacuum drying and recrystallization from alkanes, have led to the formation of diaquapentakis[bis(2,6‐diisopropylphenyl) phosphato]‐μ‐hydroxido‐dilanthanum hexane disolvate, [La₂(C₂₄H₃₄O₄P)₅(OH)(H₂O)₂]·2C₆H₁₄, ( 1 )·2(hexane), and tetraaquatetrakis[bis(2,6‐diisopropylphenyl) phosphato]‐μ‐hydroxido‐dineodymium bis(2,6‐diisopropylphenyl) phosphate heptane disolvate, [Nd₂(C₂₄H₃₄O₄P)₄(OH)(H₂O)₄]·2C₆H₁₄, ( 2 )·2(heptane). The compounds crystalize in the P2₁/n and P space groups, respectively. The diaryl‐substituted organophosphate ligand exhibits three different coordination modes, viz. κ²O,O′‐terminal [in ( 1 ) and ( 2 )], κO‐terminal [in ( 1 )] and μ₂‐κ¹O:κ¹O′‐bridging [in ( 1 ) and ( 2 )]. Binuclear structures ( 1 ) and ( 2 ) are similar and have the same unique Ln₂(μ‐OH)(μ‐OPO)₂ core. The structure of ( 2 ) consists of an [Nd₂{(2,6‐ⁱPr₂C₆H₃‐O)₂POO}₄(OH)(H₂O)₄]⁺ cation and a [(2,6‐ⁱPr₂C₆H₃‐O)₂POO]⁻ anion, which are bound via four intermolecular O—H…O hydrogen bonds. The molecular structure of ( 1 ) displays two O—H…O hydrogen bonds between OH/H₂O ligands and a κ¹O‐terminal organophosphate ligand, which resembles, to some extent, the `free' [(2,6‐ⁱPr₂C₆H₃‐O)₂POO]⁻ anion in ( 2 ). NMR studies have shown that the formation of ( 1 ) undoubtedly occurs due to intramolecular hydrolysis during vacuum drying of the aqueous La tris(phosphate) complex. Catalytic experiments have demonstrated that the presence of the coordinated hydroxide anion and water molecules in precatalyst ( 2 ) substantially lowered the catalytic activity of the system prepared from ( 2 ) in butadiene and isoprene polymerization compared to the catalytic system based on the neodymium tris[bis(2,6‐diisopropylphenyl) phosphate] complex, which contains neither OH nor H₂O ligands.     

Poly(ethylene terephthalate) synthesis catalysed by chelated Sn,Zn and Mg complexes

A series of four C,N‐chelated diorganotin(IV) compounds, namely (L^CN)₂Sn(OCH₂CH₂O) ( 1 ), [L^CNBuSn(OCH₂CH₂O)]₂ ( 2 ), (L^CN)₂Sn(1,2‐(O)₂‐3,5‐tBu₂C₆H₂) ( 3 ) and [L^CNBuSn(1,2‐(O)₂‐3,5‐tBu₂C₆H₂)]₂ ( 4 ) (L^CN = 2‐(Me₂NCH₂)C₆H₄), one zinc species, namely L^NOZnEt ( 5 ) (L^NO = [2‐(MeO)C₆H₄]NC(Me)?C(H)C(Me)?O), and one magnesium complex, namely [L^NNMg]₆ ( 6 ), (L^NN = [2‐(Me₂NCH₂)C₆H₄]N), were used as catalysts for the synthesis of poly(ethylene terephthalate) (PET) from dimethyl terephthalate and ethylene glycol. Prepared PET samples were primarily characterized using the size exclusion chromatography technique. The highest number‐average molar mass of prepared PET samples reached 10.7 kg mol^?1. Novel dimeric compound 2 was structurally characterized using both multinuclear NMR spectroscopy and X‐ray diffraction analysis. In addition, an alternative synthesis of 1 is described. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of Heteroleptic Cerium(IV) Complexes Using a Heptadentate (N4O3) Tripodale Schiff‐base Ligand

The Cerium(IV) complexes [{N[CH₂CH₂N=CH(2‐O‐3,5‐^tBu₂C₆H₂)]₃}CeCl] ( 1 ) and [{N[CH₂CH₂N=CH(2‐O‐3,5‐^tBu₂C₆H₂)]₃}Ce(NO₃)] ( 2 ) were derived from the condensation of tris(2‐aminoethyl)amine and 3,5‐di‐tert‐butylsalicylaldehyde and the appropriate Ce starting material CeCl₃(H₂O)₆ and (NH₄)₂[Ce(NO₃)₆], respectively. Single crystal X‐ray diffraction studies reveal monomeric complexes.     

Hexakis(2,4,6‐triisopropylphenyl)cyclotristannoxane – a Molecular Diorganotin Oxide with Kinetically Inert Sn–O Bonds

The single‐crystal X‐ray structure analysis of hexakis(2,4,6‐triisopropylphenyl)cyclotristannoxane, cyclo‐[(2,4,6‐i‐Pr₃‐C₆H₂)₂SnO]₃ ( 1 ), is reported and reveals this compound to contain an almost planar six‐membered ring. Redistribution reactions of 1 with cyclo‐(t‐Bu₂SnO)₃ and t‐Bu₂SiCl₂, respectively, failed and indicate an unusual kinetic inertness of the Sn–O bonds in 1 as compared to related molecular diorganotin oxides containing less bulkier substituents. The redistribution reaction of cyclo‐(t‐Bu₂SnO)₃ with cyclo‐(t‐Bu₂SnS)₂ leads to an equilibrium involving the trimeric diorganotin oxysulphides cyclo‐t‐Bu₂Sn(OSnt‐Bu₂)₂S ( 2 a ) and cyclo‐t‐Bu₂Sn(SSnt‐Bu₂)₂O ( 2 b ).     

Isomorphous rare‐earth tris[bis(2,6‐diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3‐diene polymerization and in the inhibited oxidation of polydimethylsiloxane

Crystals of mononuclear tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]pentakis(methanol‐κO)lanthanide methanol monosolvates of lanthanum, [La(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 1 ), cerium, [Ce(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 2 ), and neodymium, [Nd(C₂₄H₃₄O₄P)₃(CH₃OH)₅]·CH₃OH, ( 3 ), have been obtained by reactions between LnCl₃(H₂O)_n (n = 6 or 7) and lithium bis(2,6‐diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds ( 1 )–( 3 ) crystallize in the monoclinic P2₁/c space group and have isomorphous crystal structures. All three bis(2,6‐diisopropylphenyl) phosphate ligands display a κO‐monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅] molecular unit exhibits four intramolecular O—H…O hydrogen bonds, forming six‐membered rings. The unit forms two intermolecular O—H…O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O₂P(O‐2,6‐ⁱPr₂C₆H₃)₂}₃(CH₃OH)₅]·CH₃OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen‐bond network. Complexes ( 1 )–( 3 ) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound ( 2 ) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6‐diisopropylphenyl) phosphato‐κO]neodymium, ( 3′ ), which was obtained as a dry powder of ( 3 ) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.