A Germylene Supported by Two 2-Pyrrolylphosphane Groups as Precursor to PGeP Pincer Square-Planar Group 10 Metal(II) and T-Shaped Gold(I) Complexes

An efficient synthesis of 2-di-tert-butylphosphanylmethylpyrrole (HpyrmPtBu₂), by treating 2-dimethylaminomethylpyrrole (HpyrmNMe₂) with tBu₂PH at 135 °C in the absence of any solvent, has allowed the preparation of the new PGeP germylene Ge(pyrmPtBu₂)₂ ( 1 ), by treating [GeCl₂(dioxane)] with LipyrmPtBu₂, in which the Ge atom is stabilized by intramolecular interactions with one (solid state) or both (solution) of its phosphane groups. Reactions of germylene 1 with Group 10 metal dichlorido complexes containing easily displaceable ligands have led to [MCl{κ³P,Ge,P-GeCl(pyrmPtBu₂)₂}] [M=Ni ( 2 ), Pd ( 3 ), Pt ( 4 )], which have an unflawed square-planar metal environment. Treatment of germylene 1 with [AuCl(tht)] (tht=tetrahydrothiophene) rendered [Au{κ³P,Ge,P-GeCl(pyrmPtBu₂)₂}] ( 5 ), which is a rare case of a T-shaped gold(I) complex. The hydrolysis of 5 gave the linear gold(I) derivative [Au(κP-HpyrmPtBu₂)₂]Cl ( 6 ). Complexes 2 – 5 contain a PGeP pincer chloridogermyl ligand that arises from the insertion of the Ge atom of germylene 1 into a M−Cl bond of the corresponding metal reagent. The bonding in these molecules has been studied by DFT/NBO/QTAIM calculations. These results demonstrate that the great flexibility of germylene 1 makes it a better precursor to PGeP pincer complexes than the previously known germylenes of this type.     

Halogenation and Nucleophilic Quenching: Two Routes to E−X Bond Formation in Cobalt Triple-Decker Complexes (E=As,P; X=F,Cl, Br,I)

The oxidation of [(Cp’’’Co)₂(μ,η² : η²-E₂)₂] (E=As ( 1 ), P ( 2 ); Cp’’’=1,2,4-tri(tert-butyl)cyclopentadienyl) with halogens or halogen sources (I₂, PBr₅, PCl₅) was investigated. For the arsenic derivative, the ionic compounds [(Cp’’’Co)₂(μ,η⁴ : η⁴−As₄X)][Y] (X=I, Y=[As₆I₈]_0.5 ( 3 a ), Y=[Co₂Cl_6-nI_n]_0.5 (n=0, 2, 4; 3 b ); X=Br, Y=[Co₂Br₆]_0.5 ( 4 ); X=Cl, Y=[Co₂Cl₆]_0.5 ( 5 )) were isolated. The oxidation of the phosphorus analogue 2 with bromine and chlorine sources yielded the ionic complexes [(Cp’’’Co)₂(μ-PBr₂)₂(μ-Br)][Co₂Br₆]_0.5 ( 6 a ), [(Cp’’’Co)₂(μ-PCl₂)₂(μ-Cl)][Co₂Cl₆]_0.5 ( 6 b ) and the neutral species [(Cp’’’Co)₂(μ-PCl₂)(μ-PCl)(μ,η¹ : η¹-P₂Cl₃] ( 7 ), respectively. As an alternative approach, quenching of the dications [(Cp’’’Co)₂(μ,η⁴ : η⁴-E₄)][TEF]₂ (TEF=[Al{OC(CF₃)₃}₄]⁻, E=As ( 8 ), P ( 9 )) with KI yielded [(Cp’’’Co)₂(μ,η⁴ : η⁴-As₄I)][I] ( 10 ), representing the homologue of 3 , and the neutral complex [(Cp’’’Co)(Cp’’’CoI₂)(μ,η⁴ : η¹-P₄)] ( 11 ), respectively. The use of [(CH₃)₄N]F instead of KI leads to the formation of [(Cp’’’Co)₂(μ-PF₂)(μ,η² : η¹ : η¹-P₃F₂)] ( 12 ) and 2 , thereby revealing synthetic access to polyphosphorus compounds bearing P−F groups and avoiding the use of very strong fluorinating reagents, such as XeF₂, that are difficult to control.     

Syntheses and Crystal Structures of Two New Main Group Metal Complexes （M = Al, Bi） with the Substituted p-Hydroquinones

The title complexes [Al(Hcah)(H2O)2]·2H2O (A) and [Bi(Hcah)(H2O)]n (B), where H4cah = 2-[N,N-bis(carboxymethyl)aminomethyl] hydroquinone, have been synthesized and characterized using X-ray single-crystal structure determination, IR and elemental analysis. Both complexes crystallize in the monoclinic system, space group P21/c with a = 7.8660(16), b = 10.096(2), c = 19.053(4) and β = 93.50(3)° for A; and those for B: a = 9.2348(18), b = 7.9061(16), c = 17.141(3) and β = 102.64(3)°. In addition, further investigation revealed that the central Al(III) ion in the mononuclear complex A is in a distorted octahedral coordination geometry, while structural analysis reveals that the Bi(III) ion is in a distorted pentagonal bipyramid, forming a 2-D polymeric complex B, and the coordination network is a 2D 4.82 net. The TG analyses of A indicate two steps of water loss.     

Stabilities,Electronic Structures,and Bonding Properties of Iron Complexes (E1E2)Fe(CO)2(CNArTripp2)2 (E1E2=BF,CO, N2, CN−, or NO+)**

The coordination of 10-electron diatomic ligands (BF, CO N₂) to iron complexes Fe(CO)₂(CNAr^Tripp2)₂ [Ar^Tripp2=2,6-(2,4,6-(iso-propyl)₃C₆H₂)₂C₆H₃] have been realized in experiments very recently (Science, 2019 , 363, 1203–1205). Herein, the stability, electronic structures, and bonding properties of (E₁E₂)Fe-(CO)₂(CNAr^Tripp2)₂ (E₁E₂=BF, CO, N₂, CN⁻, NO⁺) were studied using density functional (DFT) calculations. The ground state of all those molecules is singlet and the calculated geometries are in excellent agreement with the experimental values. The natural bond orbital analysis revealed that Fe is negatively charged while E₁ possesses positive charges. By employing the energy decomposition analysis, the bonding nature of the E₂E₁–Fe(CO)₂(CNAr^Tripp2)₂ bond was disclosed to be the classic dative bond E₂E₁→Fe(CO)₂(CNAr^Tripp2)₂ rather than the electron-sharing double bond. More interestingly, the bonding strength between BF and Fe(CO)₂(CNAr^Tripp2)₂ is much stronger than that between CO (or N₂) and Fe(CO)₂(CNAr^Tripp2)₂, which is ascribed to the better σ-donation and π back-donations. However, the orbital interactions in CN⁻→Fe(CO)₂(CNAr^Tripp2)₂ and NO⁺→Fe(CO)₂(CNAr^Tripp2)₂ mainly come from σ-donation and π back-donation, respectively. The different contributions from σ donation and π donation for different ligands can be well explained by using the energy levels of E₁E₂ and Fe(CO)₂(CNAr^Tripp2)₂ fragments.     

Dinitrogen Activation and Addition to Unsaturated C−E (E=C,N, O,S) Bonds Mediated by Transition Metal Complexes

Dinitrogen (N₂) activation and functionalization is of fundamental interest and practical importance. This review focuses on N₂ activation and addition to unsaturated substrates, including carbon monoxide, carbon dioxide, heteroallenes, aldehydes, ketones, acid halides, nitriles, alkynes, and allenes, mediated by transition metal complexes, which afforded a variety of N−C bond formation products. Emphases are placed on the reaction modes and mechanisms. We hope that this work would stimulate further explorations in this challenging field.     

Transient Dipnictyl Analogues of Acrylamides,R−E=E′−CONR2, and a Related Diphosphadigalletane from Na[OCP] and (R2N)2ECl (E,E′=P,As, Ga)

The reaction of Na[OCP] with (R₂N)₂ECl (E=P or As; R=alkyl) granted direct access to transient amine-substituted diphospha- and arsaphospha-acrylamide analogues, (R₂N)E=P(CONR₂) 1 . Their facile formation allowed for a comprehensive reactivity study. Dimerization yielded the four-membered rings (R₂N)₂E₂P₂(CONR₂)₂, whereas in the presence of excess Na[OCP], a stepwise [2+2] cycloaddition occured, leading to the sodium salts of carboxotripnictides [(R₂N)EP₂CO(CONR₂)]⁻. These salts served as a reservoir of 1 , either by extrusion of Na[OCP] or by reaction with the appropriate (R₂N)₂ECl, giving the [4+2]-cycloaddition products (R₂N)EP(C₆H₁₀)(CONR₂) in the presence of 2,3-dimethylbutadiene. The formal conjugate addition product K[(tBuO)(R₂N)PP(CONR₂)] was obtained by reaction of Na[(R₂N)PP₂CO(CONR₂)] with tBuOK. In addition, a rare diphosphadigalletane with a ladder-type (R₂N)₂Ga₂P₂(CONR₂)₂ core was isolated from the reaction of Na[OCP] with (R₂N)₂GaCl (R=alkyl). The unprecedented pnictogenyl carboxamide compounds were thoroughly characterized, including single-crystal X-ray structure determinations, and mechanisms for their formation were investigated by DFT calculations.     

Backbone Reactivity of Lithium β-Diketiminate (NacNac) Complexes with CO2, tBuNCO and iPrNCO

Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO₂ gives an eight-atom carboxylate (Li₂O₄C₂) ring at the γ-C site in a dimer. Insertion of tBuNCO gives a secondary amide at the γ-C site in a monomer with TMEDA chelating lithium. Double insertion of tBuNCO and (adventitious) oxygen gives a dimer with a (LiO)₂ central core involving the latter source. Insertion of less bulky (iPrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.     

Low-Valent Group 14 Phosphinidenide Complexes [({SIDipp}P)2M] Exhibit P–M pπ–pπ Interaction (M=Ge,Sn, Pb)

Herein, the synthesis of new low-valent Group 14 phosphinidenide complexes [({SIDipp}P)₂M ] exhibiting P–M pπ–pπ interactions (SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene, M=Ge, Sn, Pb), is presented. These compounds were investigated by means of structural, spectroscopic, and quantum-chemical methods. Furthermore, the monosubstituted compounds [(SIDippP)MX]₂ (M=Sn, X=Cl; M=Pb, X=Br) are presented, which show dimeric structures instead of multiple bonding interaction.     

Hydrothermal Synthesis, Crystal Structures of Three New Metal (Ⅱ) Complexes with 1-Adamantaneacetic Acid

Three new complexes constructed by 1‐adamantaneacetic acid (HL), [Zn₂L₄]_n ( 1 ), [MnL₂(4,4′‐bipy)(H₂O)₂]_n· 2n(HL) ( 2 ) and MnL₂(2,2'‐bipy)(H₂O)₂ ( 3 ), have been hydrothermally synthesized. X‐ray single crystal diffraction analyses reveal that both 1 and 2 are infinite 1D chains along b axis. 2 and 3 have an octahedral coordination and show the supramolecular structures which are formed on the basis of the connectivity of intermolecular hydrogen bonds. The deprotonated L^? ligands coordinate the M(II) atoms with many coordination modes in the title complexes.     

X?X Through‐Cage Bonding in Cu,Ni, and Cr Complexes with M3X2 Cores (X=S,As)

Density functional calculations on trinuclear complexes bridged by two sulfur atoms, [(tmeda)₃Cu₃(μ‐S)₂]³⁺, [(tmeda)₃Ni₃(μ‐S)₂]²⁺, and [(tmeda)₃Ni₃(μ‐S₂)]⁴⁺, as well as on the formation of [(tmeda)₃Cu₃(μ‐S)₂]³⁺ from a dinuclear [(tmeda)₂Cu₂(μ‐S₂)]²⁺ complex and a mononuclear [(tmeda)Cu(η²‐S₂)]⁺ fragment, are reported. A qualitative orbital analysis of the M₃X₂ framework bonding is presented for the case in which each metal atom M has a square planar coordination sphere completed by one bidentate or two monodentate ligands (that is, [(L₂M)₃X₂] compounds). It is concluded that a framework electron count (FEC) of 12 corresponds to systems with six M? X bonds but no X? X bond through the cage, while an FEC of 10 favors the formation of an X? X bond. Framework electron counting rules are also presented for related M₃X₂ cores in [(L₅M)₃X₂] complexes, based on a qualitative molecular orbital (MO) analysis supported by DFT calculations on [(OC)₁₅Cr₃(μ‐As₂)].     

M≡E and M=E Complexes of Iron and Cobalt that Emphasize Three-fold Symmetry (E = O, N, NR)

Mid-to-late transition metal complexes that feature terminal, multiply bonded ligands such as oxos, imides, and nitrides have been invoked as intermediates in several catalytic transformations of synthetic and biological significance. Until about ten years ago, isolable examples of such species were virtually unknown. Over the past decade or so, numerous chemically well-defined examples of such species have been discovered. In this context, the presentreview summarizes the development of 4- and 5-coordinate Fe(E) and Co(E) species under local three-fold symmetry.     

Conversion of E4 (E4=P4, As4, AsP3) by Ni(0) and Ni(I) Synthons – A Comparative Study

The reactivity of white phosphorus and yellow arsenic towards two different nickel nacnac complexes is investigated. The nickel complexes [(L¹Ni)₂tol] ( 1 , L¹=[{N(C₆H₃ⁱPr₂-2,6)C(Me)}₂CH]⁻) and [K₂][(L¹Ni)₂(μ,η^{1 : 1}-N₂)] ( 6 ) were reacted with P₄, As₄ and the interpnictogen compound AsP₃, respectively, yielding the homobimetallic complexes [(L¹Ni)₂(μ-η²,κ¹:η²,κ¹-E₄)] (E=P ( 2 a ), As ( 2 b ), AsP₃ ( 2 c )), [(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 3 a ), As ( 3 b )) and [K@18-c-6(thf)₂][L¹Ni(η^{1 : 1}-E₄)] (E=P ( 7 a ), As ( 7 b )), respectively. Heating of 2 a , 2 b or 2 c also leads to the formation of 3 a or 3 b . Furthermore, the reactivity of these compounds towards reduction agents was investigated, leading to [K₂][(L¹Ni)₂(μ,η^{2 : 2}-P₄)] ( 4 ) and [K@18-c-6(thf)₃][(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 5 a ), As ( 5 b )), respectively. Compound 4 shows an unusual planarization of the initial Ni₂P₄-prism. All products were comprehensively characterized by crystallographic and spectroscopic methods.     

Two Novel Copper(Ⅱ) Complexes with A Novel Ligand 2,4-Di(2-aminopyridine)-6-methylpyrimidine

Introduction The design and syntheses of multidentate N-donor ligands have become the focus of much inter-est in the chemical field[1-4]because these ligands can form multinuclear metalxompounds, coordina-tion polymers and supramolecular compounds,which play a very important role in the bilolgicalsystems, magnetic materials,electric materials,optical materials and otherfields[5-8].     

The photo-induced decarbonylation of Cp′M(NO)(CO)2 (M = Cr,Mo, W) with diorgano dichalcogenides (R2E2; E = S,Se; R = Me,Ph)

The photo-induced decarbonylation of CpCr(NO)(CO)₂ (1a) in MeCN solution in the presence of R₂E₂ (E = S, Se; R = Me, Ph) leads to the formation of chalcogenolato-bridged binuclear complexes Cp₂Cr₂(NO)₂(-ER)₂ [E = S; R = Me (2a), Ph (3a); E = Se, R = Me (4a), Ph (5a)] while reactions between CpM(NO)(CO)₂ [M = Mo (1b), W (1c)] and Ph₂E₂ (E = S, Se) result in mononuclear complexes CpM(NO)(EPh)₂ [M = Mo; E = S (9b), Se (10b); M = W, E = S (11c), Se (12c)]. The corresponding reactions of (1b) with Me₂E₂ (E = S, Se) yielded both mono and binuclear complexes: CpMo(NO)(SeMe)₂ (8b), Cp₂Mo₂(NO)₂(-EMe)₂ [E = S (6b), Se (7b)]. The new complexes have been characterized by i.r., ¹H-, ¹³C-n.m.r. spectra and by electron-impact mass spectrometry.     

Some Aryl Substituted Metal Phosphorus Double Bonded Complexes C5R5 (CO)2 M=PR′2 (R=H,CH3; M=Mo,W)

Abstract

The attempt to generate the metal-phosphorus double bonded system Cp(CO)₂M=PPh₂ (M=Mo, W) (4a,b) via thermal or photochemical decarbonylation of Cp(CO)₃M-PPh₂ (la,b) leads to the formation of hydrido-phosphido-bridged complexes (μ2-H) (μ2-PPh₂)[M(CO)₂Cp]₂ (2a,b).     

Syntheses and Crystal Structures of Two Cyano-bridged Bimetallic Complexes [Ln(DMSO)2(H2O)(μ-CN)4Fe(CN)2](Ln= Ce and Eu, DMSO= Dimethylsulfoxide) with Layered Structure

Two new bimetallic cyano-bridged complexes [Ln(DMSO)2(H2O)(μ-CN)4Fe(CN)2] (Ln = Ce 1, Eu 2) have been prepared by the grinding reaction method and structurally characterized by X-ray single-crystal structure analysis. Crystallographic data for 1: C10H14CeFeN6O3S2, Mr = 526.36, monoclinic, P2/n, a = 7.852(4), b = 10.729(5), c = 11.181(5) (A), β = 96.992(8)°, V = 935.0(7) A3, Z = 2, Dc = 1.870 g/cm3, μ = 3.421 mm-1, F(000) = 512, R = 0.0363 and wR = 0.0971; and those for 2: C10H14EuFeN6O3S2, Mr = 538.20, monoclinic, P2/n, a = 7.739(5), b = 10.668(7), c = 11.008(7) A, β = 96.943(3)°, V = 902.1(11) A3, Z = 2, Dc = 1.981 g/cm3, μ= 4.499 mm-1, F(000) = 522, R = 0.0345 and wR = 0.0855. In each complex the lanthanide ion is seven-coordinated in a pentagonal bipyramidal arrangement, and the Fe(Ⅲ) ion is in a nearly regular octahedral environment. The title complexes can be described as two-dimensional (2-D) stair-like structures, which are further connected by hydrogen bonds to form three-dimensional (3-D) frameworks.     

Two New Copper(Ⅱ) Complexes with p-Cyanobenzoic Acid: Synthesis,Crystal Structures and Properties

The complexes of [Cu(bpy)(H2O)(CBA)2]n 1 and [Cu(phen)(H2O)(CBA)2]·H2O 2 based on p-cyanobenzoic acid(HCBA) have been synthesized in aqueous ethanolic solution at room temperature. The single-crystal X-ray diffraction studies demonstrated that complex 1 crystallizes in orthorhombic and complex 2 is of triclinic system. The results indicate the complex 1 shows a 1D chain structure bridged by two carboxylic oxygen atoms from CBA–, and complex 2 is a mononuclear structure. Through intermolecular hydrogen bonding and π...π stacking interactions, the complexes are assembled into supramolecular structures. Complex 1 has been characterized by magnetic measurements. The magnetic measurement indicates that weak ferromagnetic interaction(zJ= 0.038(5)) between the Cu2+ ions is dominant in the structure. The IR spectrum and results of thermal and elemental analyses are also presented.     

Übergangsmetallcarbin-komplexe: LXXXV. Strukturuntersuchungen der reaktionsprodukte von trans-Br(CO)2L2LCNEt2 (L2 = 2,2′-bipyridyl, 1,10-phenanthrolin) mit den organylanionen [(CO)5MEPh2]− (M = Cr,Mo, W; E = P,As, Sb)

The reaction of trans-Br(CO)₂L₂WCNEt₂ (L₂ = 2,2′-bipyridyl (2,2′-bipy), 1,10-phenanthroline (ophen)) with organyl anions of Main Group V elements coordinated to a pentacarbonylmetal fragment of the general formula [(CO)₅MEPh₂]⁻ (M = Cr, Mo, W; E = P, As, Sb) leads, by substitution of the bromine ligand, to new neutral diethylaminocarbyne complexes of the type (CO)₅MEPh₂(CO)₂L₂-WCNEt₂ (M = Cr, Mo, W; E = P, As, Sb; L₂ = 2,2′-bipy, ophen) which contain a heavier element of Main Group V in a bridging position between two transition metals. Spectroscopic investigations at low temperatures show that the bridged complexes exist as a mixture of cis and trans isomers, with the thermodynamic equilibrium favouring the cis complexes. Temperature dependent NMR spectra indicate a dynamic process in which the chelating ligand L₂ (L₂ = 2,2′-bipy, ophen) switches between two cis and two cis / trans positions, relative to the carbyne ligand, and causes a rapid interconversion of the two stereoisomers at room temperature.