Substituted Cyclooctatetraene Complexes of Yttrium and Erbium with Bis(phosphinimino)methanides — Synthesis and Structure

A one pot reaction of Li₂{1, 4‐(Me₃Si)₂C₈H₆}, LnCl₃, and K{CH(PPh₂NSiMe₃)₂} leads to the 1, 4‐bis(trimethylsilyl)cyclooctatetraene bis(phosphinimino)methanide complexes of yttrium and erbium, [{CH(PPh₂NSiMe₃)₂}Ln(η⁸‐{1, 4‐(Me₃Si)₂C₈H₆})] (Ln = Y, Er). Both complexes have been characterized by single crystal X‐ray diffraction. The solid state structures show that the two bulky ligands cause a steric crowding around the lanthanide atom. As a result of this steric crowding both ligands are asymmetrically attached to the lanthanide atom.     

Copper(I) and Gold(I) Complexes with N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine as Ligand: Synthesis and Molecular Structures

Reaction of CuI with 1 or 2 equivalent(s) N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine (BDDP) gives two different complexes, [Cu(I)μ‐(BDDP‐κP,N_py)]₂ ( 1 ) and [Cu(BDDP‐κP,N_py)₂]I ( 2 ), in high yields. The determination of the molecular structure show that both Cu^I atoms are tetrahedrally coordinated, rather than a square‐planar geometry reported for Cr⁰, Ni^II‐BDDP complexes before, which contains a planar tridentate chelate ring system. The introduction of AuCl(tht) (tht = tetrahydrothiophene) into [Cu(BDDP‐κP,N_py)₂]I leads unexpectedly to the formation of a digold complex 2,6‐[(ClAuPh₂P)HN]₂C₅H₃N and dimeric [Cu(I)μ‐(BDDP‐κP,N_py)]₂.     

Pyridyl Containing 1,5‐Diaza‐3,7‐diphosphacyclooctanes as Bridging Ligands for Dinuclear Copper(I) Complexes

1,5‐bis(R)‐3,7‐bis[2‐(pyridine‐2′‐yl)ethyl)‐1,5‐diaza‐3,7‐diphosphacyclooctanes 1 and 2 and their copper(I) complexes 3 and 4 were developed. The butterfly‐shaped copper‐iodide core and unusual P,N‐chelate and P,P‐bridged coordination mode of the heterocyclic ligand in the dinuclear complexes 3 and 4 were revealed. Complexes 3 and 4 display emission in green range of spectra, with lifetimes in a microsecond domain and quantum yields of luminescence in solid‐state up to 38 %. Thermochromic effects found for the phosphorescence of 4 in solutions are ascribed to rigidochromism.     

Synthesis,Crystal Structures and Spectrothermal Characterization of a Heptacoordinated Dimeric Salicylato Cadmium(II) Complex with 2,2′‐Azobispyridine (abpy), (µ‐abpy)[Cd(Hsal)2(abpy)]2

µ‐2,2′‐Azobispyridinebis[2,2′‐azobispyridinesalicylato(O)salicylato(O,O′) cadmium(II)], (µ‐abpy)[Cd(Hsal)₂(abpy)]₂ ( I ) was synthesized and characterized by IR and UV/ Vis spectroscopy, thermal analysis, and X‐ray diffraction techniques. Two abpy ligands and two salicylato ligands coordinate to the Cd²⁺ ion in a monocapped trigonal‐prismatic arrangement. The capping atom is the N3 atom. One of the two abpy ligands behaves as a “s‐frame” bridging ligand and adopts a s‐cis/ E/ s‐cis conformation, whereas the other one adopts as a s‐cis/ E/ s‐trans conformation. One of the two salicylato ligands acts as a monodentate ligand, which coordinates with the carboxylate oxygen atom, whereas the other one adopts bidentate coordination through two carboxylate oxygen atoms. The hydroxy groups of salicylato ligands, which coordinate in a monodentate fashion, are disordered over two positions, with occupancies of 0.52 for group A and 0.48 for group B. The decomposition reaction takes place in the temperature range 20–1000 °C under nitrogen. Thermal decomposition of the title complex proceeds in two stages.     

Gold(I)/Gold(III) Catalysis that Merges Oxidative Addition and π‐Alkene Activation

Heteroarylation of alkenes with aryl iodides was efficiently achieved with a (MeDalphos)AuCl complex through Au^I/Au^III catalysis. The possibility to combine oxidative addition of aryl iodides and π‐activation of alkenes at gold is demonstrated for the first time. The reaction is robust and general (>30 examples including internal alkenes, 5‐, 6‐, and 7‐membered rings). It is regioselective and leads exclusively to trans addition products. The (P,N) gold complex is most efficient with electron‐rich aryl substrates, which are troublesome with alternative photoredox/oxidative approaches. In addition, it provides a very unusual switch in regioselectivity from 5‐exo to 6‐endo cyclization between the Z and E isomers of internal alkenols.     

Bulky Amido Ligands in Rare Earth Chemistry — Syntheses,Structures, and Catalysis

The amido metal chemistry of the rare earth elements is a rapid developing area in coordination chemistry. Especially bulky mono and bidentate amido and amidinates have been introduced as ligands in rare earth chemistry. Due to these sterically demanding ligands, the coordination numbers of the rare earth elements are significantly reduced. This article focuses on two of these bulky ligand systems: bis(trimethylsilyl)amide and aminotroponiminates. The homoleptic bis(trimethylsilyl)amides of rare earth elements, [Ln{N(SiMe₃)₂}₃], are well established compounds in synthetic chemistry. Therefore, this article reviews recent progress in the catalytic application of these compounds. In the second part of this research report, it is shown that N, N′‐disubstituted aminotroponiminates and mono bridged bisaminotroponiminates can be used as cyclopentadienyl alternatives. Achiral and chiral aminotroponiminates have been used. The structural properties, reactivities as well as the catalytic and synthetic applications of the aminotroponiminates complexes will be outlined in this article.     

Synthesis of Differently Substituted N- and P-Aminodiphosphinoamine PNPN-H Ligands

Abstract

On the basis of the known aminodiphosphinoamine ligand Ph₂PN(i-Pr)P(Ph) N(i-Pr)-H (3a), differently substituted aminodiphosphinoamine PNPN-H ligands (3) were prepared. By using different synthetic methods, the N-substituted ligands Ph₂PN (i-Pr)P(Ph)N(c-Hex)-H (3b), Ph₂PN(c-Hex)P(Ph)N(i-Pr)-H (3g), and Ph₂PN(i-Pr)P(Ph) N[(CH₂)₃Si(OEt)₃]-H (3c), in addition to the formerly described Ph₂PN(n-Hex)P (Ph)N (i-Pr)-H (3h), Ph₂PN(i-Pr)P(Ph)N(Et)-H (3d), Ph₂PN(i-Pr)P(Ph)N(Me)-H (3e), and Ph₂PN(c-Hex)P(Ph)N(c-Hex)-H (3f), were obtained. In addition, Ph₂PN(i-Pr)P(Me)N(i-Pr)-H (3i), (cyclopentyl)₂PN(i-Pr)P(Ph)N(i-Pr)-H (3j), (-O-CH₂-CH₂-O-)PN(i-Pr)P(Ph)N(i-Pr)-H (3k), and (1-Ad)₂PN(i-Pr)P(Ph)N(i-Pr)-H (3l) were prepared with different P-substitutions. All compounds were characterized and the molecular structures of the intermediates Ph₂PN(i-Pr)P(Ph)Cl (1a) and (cyclopentyl)₂PN(i-Pr)P(Ph)Cl (1e) and the ligand (1-Ad)₂PN(i-Pr)P(Ph)N(i-Pr)-H (3l) were investigated by single-crystal X-ray diffraction.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Ming‐Phos/Gold(I)‐Catalyzed Stereodivergent Synthesis of Highly Substituted Furo[3,4‐d][1,2]oxazines†

A gold(I)‐catalyzed asymmetric intermolecular tandem [3+3]‐cyclization reaction of 2‐(1‐alkynyl)‐2‐ alken‐1‐ones with nitrones has been developed by using Ming‐Phos as a chiral ligand. This method enables access to the stereodivergent synthesis of highly substituted furo[3,4‐d][1,2]oxazines in excellent efficiency and stereoselectivity (up to 99% yield, 99% ee, >20 : 1 dr).     

Synthesis,Structure, and Reactivity of RuII Complexes with Trimethylsilylethinylamidinate Ligands

The mononuclear amidinate complexes [(η⁶‐cymene)‐RuCl( 1a )] ( 2 ) and [(η⁶‐C₆H₆)RuCl( 1b )] ( 3 ), with the trimethylsilyl‐ethinylamidinate ligands [Me₃SiC≡CC(N‐c‐C₆H₁₁)₂]^– ( 1a^– ) and[Me₃SiC≡CC(N‐i‐C₃H₇)₂]^– ( 1b^– ) were synthesized in high yields by salt metathesis. In addition, the related phosphane complexes[(η⁵‐C₅H₅)Ru(PPh₃)( 1b )] ( 4a ) [(η⁵‐C₅Me₅)Ru(PPh₃)( 1b )] ( 4b ), and [(η⁶‐C₆H₆)Ru(PPh₃)( 1b )](BF₄) ( 5 ‐BF₄) were prepared by ligand exchange reactions. Investigations on the removal of the trimethyl‐silyl group using [Bu₄N]F resulted in the isolation of [(η⁶‐C₆H₆)Ru(PPh₃){(N‐i‐C₃H₇)₂CC≡CH}](BF₄) ( 6 ‐BF₄) bearing a terminal alkynyl hydrogen atom, while 2 and 3 revealed to yield intricate reaction mixtures. Compounds 1a / b to 6 ‐BF₄ were characterized by multinuclear NMR (¹H, ¹³C, ³¹P) and IR spectroscopy and elemental analyses, including X‐ray diffraction analysis of 1b , 2 , and 3 .     

Full Protection of Intensely Luminescent Gold(I)–Silver(I) Cluster by Phosphine Ligands and Inorganic Anions

An intensely luminescent gold(I)–silver(I) cluster [(C)(AuPPhpy₂)₆Ag₆(CF₃CO₂)₃](BF₄)₅ (PPhpy₂=bis(2‐pyridyl)phenylphosphine) ( 3 ) is synthesized by the reaction of [(C)(AuPPhpy₂)₆Ag₄](BF₄)₆ with AgCF₃CO₂. All eight faces of the octahedral C@Au₆ core in 3 are capped, that is, six faces are capped by silver ions and two by tetrafluoroborates. Cluster 3 is intensely luminescent in solution with a quantum yield of 92 %. Ligation of CF₃CO₂⁻ ions is vital for the construction and emission properties of 3 , as confirmed by DFT calculations. BF₄⁻ ions are involved in the protecting sphere of the metal core, as evidenced by ¹⁹F NMR data. The participation of phosphines, CF₃CO₂⁻, and BF₄⁻ ions in the protection of the emissive core and the enhancement of the rigidity of the cluster result in the high emission efficiency. This is the first example of organic ligands and inorganic anions forming a rigid protecting sphere for luminescent coinage‐metal clusters.     

Complexes of N‐Thiophosphorylthiourea α‐NaphthylNHC(S)NHP(S)(OiPr)2 (HL) with Copper(I). Crystal Structures of HL and Cu(PPh3)2L

Reaction of the potassium salt of N‐thiophosphorylated thiourea α‐naphthylNHC(S)NHP(S)(OiPr)₂ ( HL ) with Cu(PPh₃)₃I in aqueous EtOH/CH₂Cl₂ leads to the mononuclear complex [Cu(PPh₃)₂L–S,S′]. By using copper(I) iodide instead ofCu(PPh₃)₃I, the polynuclear complex [Cu_n(L–S,S′)_n] was obtained. The structures of these compounds were investigated by elemental analysis, ¹H and ³¹P{¹H} NMR and IR spectroscopy. The crystal structures of HL and Cu(PPh₃)₂L were determined by single‐crystal X‐ray diffraction.     

Differing Coordination Modes of (O‐Alkyl)‐p‐Ethoxyphenyldithiophosphonato Ligands in Copper(I), Silver(I) and Gold(I) Triphenylphosphine Complexes

The three (O‐methyl)‐p‐ethoxyphenyldithiophosphonato triphenylphosphine complexes of copper, silver and gold, [(Ph₃P)_nM{S₂P(OMe)C₆H₄OEt‐p}] (M = Cu, n = 2; M = Ag, Au, n = 1) investigated structurally by X‐ray diffraction exhibit remarkable structural differences. The copper compound is a four‐coordinate chelate monomer with Cu–S 2.4417(6) and 2.5048(6) Å; P–Cu–S 104.24(2)–114.01(2)°; Cu–S–P 82.49(3)° and 80.85(2)°. The silver compound is a cyclic dimer with bridging dithiophosphonato ligands and three‐coordinate silver atoms [Ag–S 2.5371(5) and 2.6867(5) Å; P–Ag–S 122.88(2)° and 122.17(2)°; Ag–S–P 89.32(2)° and 103.56(2)°]. The gold compound is monomeric with linear dicoordinate gold [Au–S 2.3218(6) Å; P–Au–S 177.72(2)°, Au–S–P 100.97(3)°].     

Synthesis and Crystal Structures of Manganese(II) and ­Cobalt(II) Complexes with 2, 6‐Dimethoxybenzoic Acid and Additional N‐Donor Ligands

Three coordination compounds [Mn₃(dmb)₆(H₂O)₄(4, 4′‐bpy)₃(EtOH)]_n ( 1 ) and [M(dmb)₂(pyz)₂ (H₂O)₂] [M^II = Co ( 2 ), Mn ( 3 )] (Hdmb = 2, 6‐dimethoxybenzoic acid, 4, 4′‐bpy = 4, 4′‐bipyridine, pyz = pyrazine) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. Compound 1 consists of infinite 1D polymeric chains, in which the metal entities are bridged by 4, 4′‐bpy ligands. There are four crystallographically independent Mn^II atoms in the linear chain with different coordination modes, which is only scarcely reported for linear polymers. The isostructural crystals of 2 and 3 are composed of neutral mononuclear complexes. In crystal the complexes are combined into chains by intermolecular O–H ··· N hydrogen bonds and π–π interactions between antiparallel pyrazine molecules.     

Catalytic Activity of Cationic and Neutral Silver(I)–XPhos Complexes with Nitrogen Ligands or Tolylsulfonate for Mannich and Aza‐Diels–Alder Coupling Reactions

Cationic and neutral silver(I)–L complexes (L=Buchwald‐type biaryl phosphanes) with nitrogen co‐ligands or organosulfonate counter ions have been synthesised and characterised through their structural and spectroscopic properties. At room temperature, both cationic and neutral silver(I)–L complexes are extremely active catalysts in the promotion of the single and double A³ coupling of terminal (di)alkynes, pyrrolidine and formaldehyde. In addition, the aza‐Diels–Alder two‐ and three‐component coupling reactions of Danishefsky’s diene with an imine or amine and aldehyde are efficiently catalysed by these cationic or neutral silver(I)–L complexes. The solvent influences the catalytic performance due to limited complex solubility or solvent decomposition and reactivity. The isolation of new silver(I)–L complexes with reagents as ligands lends support to mechanistic proposals for such catalytic processes. The activity, stability and metal–distal arene interaction of these silver(I)–L catalysts have been compared with those of analogous cationic gold(I) and copper(I) complexes.     

Synthesis and Structural Studies of New (Triphenylphosphine)(trialkoxysilanethiolato)gold(I) Complexes

Compounds of general formula Au{SSi(OR)₃}(PPh₃), R = Prⁱ ( 1 ), Bu^s ( 2 ) or Bu^t ( 3 ), have been obtained by reaction of AuCl(PPh₃) with triethylammonium salts of respective silanethiols, (RO)₃SiSH. Molecular and crystal structures of 1 , 2 , and 3 have been determined by the single crystal X‐ray structural analysis. Compounds 1 and 2 are the first structurally characterized metal derivatives of hydrolytically unstable trialkoxysilanethiols (PrⁱO)₃SiSH and (Bu^sO)₃SiSH.     

Synthesis of Gold Nanosheets through Thermolysis of Mixtures of Long Chain 1‐Alkylimidazole and Hydrogen Tetrachloroaurate(III)

Micron‐sized gold nanosheets were produced through thermolysis of a mixture composed of 1‐octa‐decanylimidazole (C₁₈‐im) and HAuCl₄ in a molar ratio of 4:1 at 200 °C for 1 h. Effects of the molar ratio of [₁₈‐im]/[HAuCl₄], the reaction temperature, and the N‐alkylimidazole chain length were studied. Adjusting the molar ratio of [C₁₈‐im]/[HAuCl₄] can tune the morphology and size of the nanostructures; the effect of reaction temperature is minimum; while using long chain imidazole tends to favor the formation of nanosheets, using 1‐methylimidazole (C₁‐im) produces micron‐sized polyhedra. The growth mechanism of these nanostructures was proposed. C₁₈‐im functions both as a templating and capping agent and favors the growth of nanosheets. On the other hand, C¹‐im functions only as a capping agent and thus favors the formation of polyhedra, especially octahedra.