Two precatalysts for application in asymmetric homogeneous hydrogenation

The title compounds, [(1R,1′R,2R,2′R)‐2,2′‐bis(diphenylphosphanyl)‐1,1′‐dicyclopentane](η⁴‐norbornadiene)rhodium(I) tetrafluoridoborate, [Rh(C₃₄H₃₆P₂)(C₇H₈)]BF₄, (I), and [(1R,1′R,2R,2′R)‐2,2′‐bis(diphenylphosphanyl)‐1,1′‐dicyclopentane][η⁴‐(Z,Z)‐cycloocta‐1,5‐diene]rhodium(I) tetrafluoridoborate dichloromethane monosolvate, [Rh(C₃₄H₃₆P₂)(C₈H₁₂)]BF₄·CH₂Cl₂, (II), are applied as precatalysts in asymmetric homogeneous hydrogenation, e.g. in the reduction of dehydroamino acids, affording excellent enantiomeric excesses [Zhu, Cao, Jiang & Zhang (1997). J. Am. Chem. Soc. 119 , 1799–1800].     

A new heteroleptic cuprous complex with strong yellow photoluminescence

In the title heteroleptic cuprous complex, (acetonitrile‐κN)({2‐[2‐(diphenylphosphanyl)phenoxy]phenyl}diphenylphosphane‐κ²P,P′)[2‐(pyridin‐4‐yl‐κN)‐1,3‐benzoxazole]copper(I) hexafluoridophosphate, [Cu(C₃₆H₂₈OP₂)(CH₃CN)(C₁₂H₈N₂O)]PF₆, conventionally abbreviated [Cu(POP)(CH₃CN)(4‐PBO)]PF₆, where POP is the diphosphane ligand {2‐[2‐(diphenylphosphanyl)phenoxy]phenyl}diphenylphosphane and 4‐PBO is the N‐containing ligand 2‐(pyridin‐4‐yl)‐1,3‐benzoxazole, the asymmetric unit consists of a hexafluoridophosphate anion and a whole mononuclear cation, where the Cu^I centre is coordinated by two P atoms from the POP ligand, by one N atom from the 4‐PBO ligand and by the N atom of the coordinated acetonitrile molecule, giving rise to a CuP₂N₂ distorted tetrahedral coordination geometry. The electronic absorption, photoluminescence and thermal stability properties of this complex have been studied on as‐synthesized samples, which had previously been examined by powder X‐ray diffraction. A yellow emission signal is attributed to an excited state arising from metal‐to‐ligand charge transfer (MLCT).     

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η2‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC1)platinum(II)]

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)platinum(II)], [Pt₂(C₁₅H₁₉O₄)₂Cl₂], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform–diethyl ether or methylene chloride–diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile‐κN)(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chloridoplatinum(II) monohydrate, [Pt(C₁₅H₁₉O₄)Cl(CH₃CN)]·H₂O, (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethylformamide‐κO)platinum(II), [Pt(C₁₅H₁₉O₄)Cl(C₂H₇NO)], and (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethyl sulfoxide‐κS)platinum(II), determined as the analogue {η²‐2‐allyl‐4‐methoxy‐5‐[(ethoxycarbonyl)methoxy]phenyl‐κC¹}chlorido(dimethyl sulfoxide‐κS)platinum(II), [Pt(C₁₄H₁₇O₄)Cl(C₂H₆OS)]. The crystal structures confirm that acetonitrile interacts with the Pt^II atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt—Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C—H…O and C—H…π interactions, but no π–π interactions are observed despite the presence of the aromatic ring.     

Crystal structure and DFT analyses of a pentacoordinated PCP pincer nickel(II) complex

The reaction of NiCl₂ with 1,3‐bis[(diphenylphosphanyl)methyl]hexahydropyrimidine in the presence of 2,6‐dimethylphenyl isocyanide and KPF₆ afforded a new pentacoordinated PCP pincer Ni^II complex, namely {1,3‐bis[(diphenylphosphanyl)methyl]hexahydropyrimidin‐2‐yl‐κN²}(2,6‐dimethylphenyl isocyanide‐κC)nickel(II) hexafluoridophosphate 0.70‐hydrate, [Ni(C₉H₉N)(C₃₀H₃₀ClN₂P₂)]PF₆·0.7H₂O or [NiCl{C(NCH₂PPh₂)₂(CH₂)₃‐κ³P,C,P′}(Xylyl‐NC)]PF₆·0.7H₂O, in very good yield. Its X‐ray structure showed a distorted square‐pyramidal geometry and the compound does not undergo dissociation in solution, as shown by variable‐temperature NMR and UV–Vis studies. Density functional theory (DFT) calculations provided an insight into the bonding; the nickel dsp²‐hybridized orbitals form the basal plane and the nearly pure p orbital forms the axial bond. This is consistent with the NBO (natural bond orbital) analysis of analogous nickel(II) complexes.     

Synthesis,characterization, and crystal structures of organonickel(II) complexes coordinated to novel 1‐bromo‐2,6‐bis{[(λ5‐phosphanylidene)imino]methyl}benzene NCN‐pincer ligands

A novel family of four 1‐bromo‐2,6‐bis{[(λ⁵‐phosphanylidene)imino]methyl}benzene ligands has been synthesized and characterized. The phosphiniminomethyl substituents are decorated with either three phenyl groups, two phenyl and one cyclohexyl group, one phenyl and two cyclohexyl groups, or three cyclohexyl groups. Each ligand was metallated using zero‐valent nickel through an oxidative addition to form a family of organonickel(II) complexes, namely (2,6‐bis{[(triphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II) dichloromethane hemisolvate, [NiBr(C₄₄H₃₇N₂P₂)]·0.5CH₂Cl₂, (2,6‐bis{[(cyclohexyldiphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II) diethyl ether hemisolvate, [NiBr(C₄₄H₄₉N₂P₂)]·0.5C₄H₁₀O, (2,6‐bis{[(dicyclohexylphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II), [NiBr(C₄₄H₆₁N₂P₂)], and (2,6‐bis{[(tricyclohexyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II), [NiBr(C₄₄H₇₃N₂P₂)]. This family of complexes represents a useful opportunity to investigate the impact of incrementally changing the steric characteristics of a complex on its structure and reactivity.     

In situ synthesis of mononuclear copper(II) complexes of the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine

Two mononuclear copper complexes, {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}(3,5‐dimethyl‐1H‐pyrazole‐κN²)(perchlorato‐κO)copper(II) perchlorate, [Cu(ClO₄)(C₅H₈N₂)(C₁₂H₁₉N₅)]ClO₄, (I), and {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}bis(3,5‐dimethyl‐1H‐pyrazole‐κN²)copper(II) bis(hexafluoridophosphate), [Cu(C₅H₈N₂)₂(C₁₂H₁₉N₅)](PF₆)₂, (II), have been synthesized by the reactions of different copper salts with the tripodal ligand tris[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (TDPA) in acetone–water solutions at room temperature. Single‐crystal X‐ray diffraction analysis revealed that they contain the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (BDPA), which cannot be obtained by normal organic reactions and has thus been captured in the solid state by in situ synthesis. The coordination of the Cu^II ion is distorted square pyramidal in (I) and distorted trigonal bipyramidal in (II). The new in situ generated tridentate BDPA ligand can act as a meridional or facial ligand during the process of coordination. The crystal structures of these two compounds are stabilized by classical hydrogen bonding as well as intricate nonclassical hydrogen‐bond interactions.     

A new heteroleptic phosphorescent cuprous complex supported by a BINAP ligand: synthesis,structure, luminescence properties and theoretical analyses

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The heteroleptic cuprous complex solvate rac‐(acetonitrile‐κN)(3‐aminopyridine‐κN)[2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl‐κ²P,P′]copper(I) hexafluoridophosphate dichloromethane monosolvate, [Cu(C₅H₆N₂)(C₂H₃N)(C₄₄H₃₂P₂)]PF₆·CH₂Cl₂, conventionally abbreviated as [Cu(3‐PyNH₂)(CH₃CN)(BINAP)]PF₆·CH₂Cl₂, ( I ), where BINAP and 3‐PyNH₂ represent 2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl and 3‐aminopyridine, respectively, is described. In this complex solvate, the asymmetric unit consists of a cocrystallized dichloromethane molecule, a hexafluoridophosphate anion and a complete racemic heteroleptic cuprous complex cation in which the cuprous centre, in a tetrahedral CuP₂N₂ coordination, is coordinated by two P atoms from the BINAP ligand, one N atom from the 3‐PyNH₂ ligand and another N atom from a coordinated acetonitrile molecule. The UV–Vis absorption and photoluminescence properties of this heteroleptic cuprous complex have been studied on polycrystalline powder samples, which had been verified by powder X‐ray diffraction before recording the spectra. Time‐dependent density functional theory (TD‐DFT) calculations and a wavefunction analysis reveal that the orange–yellow phosphorescence emission should originate from intra‐ligand (BINAP) charge transfer mixed with a little of the metal‐to‐ligand charge transfer ³(IL+ML)CT excited state.     

A 1,2,4‐diazaphospholane complex of rhodium

The crystal structure of a prospective olefin catalyst, namely {2‐[1‐acetyl‐5‐(2‐hydroxy­phenyl)‐4‐phenyl‐1,2,4‐di­aza­phospholan‐3‐yl]­phenyl acetate‐κP}chloro­(η⁴‐cyclo­octa‐1,5‐diene)rhodium(I) di­chloro­methane solvate, [RhCl(C₈H₁₂)(C₂₄H₂₃N₂O₄P)]·CH₂Cl₂, has been determined at 173 K. The five‐membered heterocycle of the phosphine ligand is in a slightly distorted twist conformation. An intramolecular N1—H1⃛Cl1 hydrogen bond contributes to the adopted conformation and may additionally participate in secondary interactions with substrates during catalysis.     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

Synthesis and Insertion Chemistry of Mixed Tether Uranium Metallocene Complexes

The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η⁵‐C₅Me₄SiMe₂CH₂‐κC)₂U] ( 1 ) with substrates that react with only one of the U? C linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining U? C bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN₃) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η⁵‐C₅Me₄SiMe₂CH₂‐κC)U(η⁵‐C₅Me₄SiMe₂‐CH₂NNN‐Ad‐κ²N^1,3)]. Similarly, a single equivalent of CS₂ reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η⁵‐C₅Me₄SiMe₂CH₂‐κC)U(η⁵‐C₅Me₄SiMe₂‐ CH₂C(S)₂‐κ²S,S′)], a reaction that constitutes the first example of CS₂ insertion into a U⁴⁺? C bond. Complex 1 reacts with one equivalent of pyridine N‐oxide by C? H bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N‐oxide complex [(η⁵‐C₅Me₄SiMe₂CH₂‐κC)(η⁵‐C₅Me₄SiMe₃)U(C₆H₄NO‐κ²C,O)]. The remaining (η⁵‐C₅Me₄SiMe₂CH₂‐κC)^2? ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η⁵‐C₅Me₄SiMe₃)U(C₅H₄NO‐κ²C,O)(η⁵‐C₅Me₄SiMe₂C(?CH₂)O‐κO)] and [(η⁵‐C₅Me₄SiMe₂CH₂NNN‐Ad‐κ²N^1,3)U(η⁵‐C₅Me₄SiMe₂C(?CH₂)O‐κO)].     

A new P,S‐coordinating ferrocenyl ligand: synthesis of a precursor and its coordination compounds with PdII and PtII

In our ongoing development of ferrocene ligands, 1‐dimethylamino‐2‐(diphenylphosphinothioyl)ferrocene is being used as a convenient building block to obtain racemic or enantiomerically pure ligands. Using this building block in large excess allowed the formation of several by‐products, two of which have already been reported; the structure of a third by‐product, namely 1‐(diphenylphosphinothioyl)‐2‐{[(diphenylphosphinothioyl)sulfanyl]methyl}ferrocene, [Fe(C₅H₅)(C₃₀H₂₅P₂S₃)], is presented here. The crystal structure is built up from a ferrocene unit, with one of the cyclopentadienyl (Cp) rings substituted in the 1‐ and 2‐positions by a protected diphenylphosphinothioyl group and a [(diphenylphosphinothioyl)sulfanyl]methyl fragment, –CH₂SP(=S)Ph₂. There are C—H...S interactions which result in the formation of chains parallel to the c axis. After desulfurization, the crude material was then reacted with Pd and Pt (M) precursors [MCl₂(CH₃CN)₂] to yield two isostructural dinuclear complexes arranged around twofold axes, namely (R,R/S,S)‐bis{μ‐[2‐(diphenylphosphanyl)ferrocen‐1‐yl]methanethiolato‐κ³P,S:S}bis[chloridopalladium(II)] pentane disolvate, [Pd₂{Fe(C₅H₅)(C₁₈H₁₅PS)}₂Cl₂]·2C₅H₁₂, and the platinum(II) analogue, (R,R/S,S)‐bis{μ‐[2‐(diphenylphosphanyl)ferrocen‐1‐yl]methanethiolato‐κ³P,S:S}bis[chloridoplatinum(II)] toluene monosolvate, [Pt₂{Fe(C₅H₅)(C₁₈H₁₅PS)}₂Cl₂]·C₇H₈, in which the two metal atoms present a slightly distorted square‐planar geometry formed by two bridging S atoms and P and Cl atoms. The P,S‐chelating ligand results from the rupture of one of the P—S bonds in the starting ligand. These dinuclear complexes display a butterfly geometry. Surprisingly, only the (R,R/S,S) diastereoisomer has been isolated.     

A new two‐dimensional CoII coordination polymer based on bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether and biphenyl‐4,4′‐diyldicarboxylic acid: synthesis,crystal structure and photocatalytic degradation activity

A novel two‐dimensional Co^II coordination framework, namely poly[(μ₂‐biphenyl‐4,4′‐diyldicarboxylato‐κ²O⁴:O^4′){μ₂‐bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether‐κ²N³:N^3′}cobalt(II)], [Co(C₁₄H₈O₄)(C₂₀H₁₈N₄O)]_n, has been prepared and characterized by IR, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. The crystal structure reveals that the compound has an achiral two‐dimensional layered structure based on opposite‐handed helical chains. In addition, it exhibits significant photocatalytic degradation activity for the degradation of methylene blue.     

Chemistry of transition‐metal complexes containing functionalized phosphines: synthesis and structural analysis of rhodium(I) complexes containing allyl and cyanoalkylphosphines

A series of related acetylacetonate–carbonyl–rhodium compounds substituted by functionalized phosphines has been prepared in good to excellent yields by the reaction of [Rh(acac)(CO)₂] (acac is acetylacetonate) with the corresponding allyl‐, cyanomethyl‐ or cyanoethyl‐substituted phosphines. All compounds were fully characterized by ³¹P, ¹H, ¹³C NMR and IR spectroscopy. The X‐ray structures of (acetylacetonato‐κ²O,O′)(tert‐butylphosphanedicarbonitrile‐κP)carbonylrhodium(I), [Rh(C₅H₇O₂)(CO)(C₈H₁₃N₂)] or [Rh(acac)(CO)(^tBuP(CH₂CN)₂}] ( 2b ), (acetylacetonato‐κ²O,O′)carbonyl[3‐(diphenylphosphanyl)propanenitrile‐κP]rhodium(I), [Rh(C₅H₇O₂)(C₁₅H₁₄N)(CO)] or [Rh(acac)(CO){Ph₂P(CH₂CH₂CN)}] ( 2h ), and (acetylacetonato‐κ²O,O′)carbonyl[3‐(di‐tert‐butylphosphanyl)propanenitrile‐κP]rhodium(I), [Rh(C₅H₇O₂)(C₁₁H₂₂N)(CO)] or [Rh(acac)(CO){^tBu₂P(CH₂CH₂CN)}] ( 2i ), showed a square‐planar geometry around the Rh atom with a significant trans influence over the acetylacetonate moiety, evidenced by long Rh—O bond lengths as expected for poor π‐acceptor phosphines. The Rh—P distances displayed an inverse linear dependence with the coupling constants J_P‐Rh and the IR ν(C[triple‐bond]O) bands, which accounts for the Rh—P electronic bonding feature (poor π‐acceptors) of these complexes. A combined study from density functional theory (DFT) calculations and an evaluation of the intramolecular H…Rh contacts from X‐ray diffraction data allowed a comparison of the conformational preferences of these complexes in the solid state versus the isolated compounds in the gas phase. For 2b , 2h and 2i , an energy‐framework study evidenced that the crystal structures are mainly governed by dispersive energy. In fact, strong pairwise molecular dispersive interactions are responsible for the columnar arrangement observed in these complexes. A Hirshfeld surface analysis employing three‐dimensional molecular surface contours and two‐dimensional fingerprint plots indicated that the structures are stabilized by H…H, C…H, H…O, H…N and H…Rh intermolecular interactions.     

Two 18ē TiIVη5‐Cp‐tris(sec‐amido)‐type complexes derived from 1H‐imidazol‐2‐yl side‐chain functionalized cyclopentadienes

Achiral {2‐[2‐(η⁵‐cyclopentadienyl)‐2‐methylpropyl]‐1H‐imidazolyl‐κN¹}bis(N,N‐diethylamido‐κN)titanium(IV), [Ti(C₄H₁₀N)₂(C₁₂H₁₄N₂)], (I), and closely related racemic (SR)‐{2‐[(η⁵‐cyclopentadienyl)(phenyl)methyl]‐1H‐imidazolyl‐κN¹}bis(N,N‐diethylamido‐κN)titanium(IV), [Ti(C₄H₁₀N)₂(C₁₅H₁₂N₂)], (II), have been prepared by direct reactions of Ti(NEt₂)₄ and the corresponding 1H‐imidazol‐2‐yl side‐chain functionalized cyclopentadienes. In compound (II), there are two crystallographically independent molecules of very similar geometries connected by a noncrystallographic pseudosymmetry operation akin to a 2₁ screw axis. All Ti‐ligating N atoms in both (I) and (II) are in planar environments, which is indicative of an additional N→Ti pπ–dπ donation. This fact and the 18ē nature of both (I) and (II) are additionally supported by quantum chemical single‐point density functional theory (DFT) computations.     

A rhodium(III) complex of the linear diborazine H3B·NMe2BH2·NMe2H: an intermediate in the dehydrocoupling of H3B·NMe2H

The solid‐state structure of the rhodium complex (dimethylamine–dimethylaminoborane–borane‐κ²H,H′)dihydridobis(triisopropylphosphane‐κP)rhodium(III) tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate, [RhH₂(C₄H₁₈B₂N₂)(C₉H₂₁P)₂](C₃₂H₁₂BF₂₄), is reported. The complex contains the linear diborazine H₃B·NMe₂BH₂·NMe₂H, a kinetically important intermediate in the transition‐metal‐mediated dehydrocoupling of H₃B·NMe₂H, ultimately affording the dimeric amino‐borane [H₂BNMe₂]₂. The structure of the title complex contains a distorted octahedral Rh^III centre, with mutually trans phosphane ligands and cis hydride ligands. The diborazine is bound through two Rh—H—B σ‐bonds and exhibits a gauche conformation with respect to the B—N—B—N backbone.     

A new phosphorescent heteroleptic cuprous complex with a neutral 2‐methylquinolin‐8‐ol ligand: synthesis,structure characterization,properties and TD–DFT calculations

Luminescent Cu^I complexes have emerged as promising substitutes for phosphorescent emitters based on Ir, Pt and Os due to their abundance and low cost. The title heteroleptic cuprous complex, [9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)‐9H‐xanthene‐κ²P ,P ](2‐methylquinolin‐8‐ol‐κ²N ,O )copper(I) hexafluorophosphate, [Cu(C₁₀H₉NO)(C₃₉H₃₂OP₂)]PF₆, conventionally abbreviated as [Cu(Xantphos)(8‐HOXQ)]PF₆, where Xantphos is the chelating diphosphine ligand 9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)‐9H‐xanthene and 8‐HOXQ is the N ,O‐chelating ligand 2‐methylquinolin‐8‐ol that remains protonated at the hydroxy O atom, is described. In this complex, the asymmetric unit consists of a hexafluorophosphate anion and a whole mononuclear cation, where the Cu^I atom is coordinated by two P atoms from the Xantphos ligand and by the N and O atoms from the 8‐HOXQ ligand, giving rise to a tetrahedral CuP₂NO coordination geometry. The electronic absorption and photoluminescence properties of this complex have been studied on as‐synthesized samples, whose purity had been determined by powder X‐ray diffraction. In the detailed TD–DFT (time‐dependent density functional theory) studies, the yellow emission appears to be derived from the inter‐ligand charge transfer and metal‐to‐ligand charge transfer (M +L ′)→LCT excited state (LCT is ligand charge transfer).     

Mononuclear Complexes of Platinum Group Metals Containing η6‐ and η5‐Cyclic Π‐Perimeter Hydrocarbon and Pyridylpyrazolyl Derivatives: Syntheses and Structural Studies

Piano‐stool‐shaped platinum group metal compounds, stable in the solid state and in solution, which are based on 2‐(5‐phenyl‐1H‐pyrazol‐3‐yl)pyridine ( L ) with the formulas [(η⁶‐arene)Ru( L )Cl]PF₆ {arene = C₆H₆ ( 1 ), p‐cymene ( 2 ), and C₆Me₆, ( 3 )}, [(η⁶‐C₅Me₅)M( L )Cl]PF₆ {M = Rh ( 4 ), Ir ( 5 )}, and [(η⁵‐C₅H₅)Ru(PPh₃)( L )]PF₆ ( 6 ), [(η⁵‐C₅H₅)Os(PPh₃)( L )]PF₆ ( 7 ), [(η⁵‐C₅Me₅)Ru(PPh₃)( L )]PF₆ ( 8 ), and [(η⁵‐C₉H₇)Ru(PPh₃)( L )]PF₆ ( 9 ) were prepared by a general method and characterized by NMR and IR spectroscopy and mass spectrometry. The molecular structures of compounds 4 and 5 were established by single‐crystal X‐ray diffraction. In each compound the metal is connected to N1 and N11 in a k² manner.     

Scandium complexes with the tetraphenylethylene and anthracene dianions

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare‐earth metal–carbon bonding. The crystal structures of (18‐crown‐6)bis(tetrahydrofuran‐κO)sodium bis(η⁶‐1,1,2,2‐tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C₄H₈O)₂(C₁₂H₂₄O₆)][Sc(C₂₆H₂₀)₂]·2C₄H₈O or [Na(18‐crown‐6)(THF)₂][Sc(η⁶‐C₂Ph₄)₂]·2(THF), ( 1b ), (η⁵‐1,3‐diphenylcyclopentadienyl)(tetrahydrofuran‐κO)(η⁶‐1,1,2,2‐tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C₁₇H₁₃)(C₂₆H₂₀)(C₄H₈O)]·0.5C₇H₈ or [(η⁵‐1,3‐Ph₂C₅H₃)Sc(η⁶‐C₂Ph₄)(THF)]·0.5(toluene), ( 5b ), poly[[(μ₂‐η³:η³‐anthracenediyl)bis(η⁶‐anthracenediyl)bis(η⁵‐1,3‐diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K₂Sc₂(C₁₄H₁₀)₃(C₁₇H₁₃)₂(C₄H₈O)₄]·C₄H₈O}_n or [K(THF)₂]₂[(1,3‐Ph₂C₅H₃)₂Sc₂(C₁₄H₁₀)₃]·THF, ( 6 ), and 1,4‐diphenylcyclopenta‐1,3‐diene, C₁₇H₁₄, ( 3a ), have been established. The [Sc(η⁶‐C₂Ph₄)₂]⁻ complex anion in ( 1b ) contains the tetraphenylethylene dianion in a symmetrical bis‐η³‐allyl coordination mode. The complex homoleptic [Sc(η⁶‐C₂Ph₄)₂]⁻ anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D ¹H and ¹³C{¹H}, and 2D COSY ¹H–¹H and ¹³C–¹H NMR data are presented for M[Sc(Ph₄C₂)₂]·xTHF [M = Na and x = 4 for ( 1a ); M = K and x = 3.5 for ( 2a )] in THF‐d₈ media. Complex ( 5b ) exhibits an unsymmetrical bis‐η³‐allyl coordination mode of the dianion, but this changes to a η⁴ coordination mode for (1,3‐Ph₂C₅H₃)Sc(Ph₄C₂)(THF)₂, ( 5a ), in THF‐d₈ solution. A ⁴⁵Sc NMR study of ( 2a ) and UV–Vis studies of ( 1a ), ( 2a ) and ( 5a ) indicate a significant covalent contribution to the Sc—Ph₄C₂ bond character. The unique Sc ate complex, ( 6 ), contains three anthracenide dianions demonstrating both a η⁶‐coordination mode for two bent ligands and a μ₂‐η³:η³‐bridging mode of a flat ligand. Each [(1,3‐Ph₂C₅H₃)₂Sc₂(C₁₄H₁₀)₃]²⁻ dianionic unit is connected to four neighbouring units via short contacts with [K(THF)₂]⁺ cations, forming a two‐dimensional coordination polymer framework parallel to (001).     

The bis(acetonitrile‐κN)bis[N,N‐bis(diphenylphosphanyl)ethanamine‐κ2P,P′]iron(II) tetrabromidoferrate(II) and μ‐oxido‐bis[tribromidoferrate(III)] complex salts

Orange crystals of bis(acetonitrile‐κN)bis[N,N‐bis(diphenylphosphanyl)ethanamine‐κ²P,P′]iron(II) tetrabromidoferrate(II), [Fe(CH₃CN)₂(C₂₆H₂₅NP₂)₂][FeBr₄], (I), and red crystals of bis(acetonitrile‐κN)bis[N,N‐bis(diphenylphosphanyl)ethanamine‐κ²P,P′]iron(II) μ‐oxido‐bis[tribromidoferrate(III)], [Fe(CH₃CN)₂(C₂₆H₂₅NP₂)₂][Fe₂Br₆O], (II), were obtained from the same solution after prolonged exposure to atmospheric oxygen, resulting in partial oxidation of the [FeBr₄]²⁻ anion to the [Br₃FeOFeBr₃]²⁻ anion. The asymmetric unit of (I) consists of three independent cations, one on a general position and two on inversion centres, with two anions, required to balance the charge, located on general positions. The asymmetric unit of (II) consists of two independent cations and two anions, all on special positions. The geometric parameters within the coordination environments of the cations do not differ significantly, with the major differences being in the orientation of the phenyl rings on the bidentate phosphane ligand. The ethyl substituent in the cation of (II) and the Br atoms in the anions of (II) are disordered. The P—Fe—P bite angles represent the smallest angles reported to date for octahedral Fe^II complexes containing bidentate phosphine ligands with MeCN in the axial positions, ranging from 70.82 (3) to 70.98 (4)°. The average Fe—Br bond distances of 2.46 (2) and 2.36 (2) Å in the [FeBr₄]²⁻ and [Br₃FeOFeBr₃]²⁻ anions, respectively, illustrate the differences in the Fe oxidation states.     

Two mononuclear Tc complexes: [2,2′‐(3‐phenylpropylimino)‐ and [2,2′‐(propylimino)bis(ethanethiolato)](4‐methoxybenzenethiolato)oxidotechnate(V)

The molecular structures of the two mononuclear title complexes, namely (4‐methoxybenzenethiolato‐κS)oxido[2,2′‐(3‐phenylpropylimino)bis(ethanethiolato)‐κ³S,N,S′]technetium(V), [Tc(C₁₄H₂₁NS₂)(C₇H₇OS)O], (I), and (4‐methoxybenzenethiolato‐κS)oxido[2,2′‐(propylimino)bis(ethanethiolato)‐κ³S,N,S′]technetium(V), [Tc(C₇H₁₅NS₂)(C₇H₇OS)O], (II), exhibit the same coordination environment for the central Tc atoms. The atoms are five‐coordinated (TcNOS₃) with a square‐pyramidal geometry comprising a tridentate 2,2′‐(3‐phenylpropylimino)bis(ethanethiolate) or 2,2′‐(propylimino)bis(ethanethiolate) ligand, a 4‐methoxybenzenethiolate ligand and an additional oxide O atom. Intermolecular C—H...O and C—H...S hydrogen bonds between the monomeric units result in two‐dimensional layers with a parallel arrangement.