Niobium isocyanide complexes,Nb(CNAr)6, with Ar = 2,6‐dimethylphenyl (Xyl), a diamagnetic dimer containing four reductively coupled isocyanides,and Ar = 2,6‐diisopropylphenyl (Dipp), a paramagnetic monomer analogous to the highly unstable hexacarbonylniobium(0)

Treatment of bis(mesitylene)niobium(0) with 6–7 equivalents of 2,6‐dimethylphenyl isocyanide (CNXyl) affords two products with the empirical formula Nb(CNXyl)_n (n = 7 or 6), which have been shown to be the diamagnetic dimers bis[μ‐N,N′,N′′,N′′′‐tetrakis(2,6‐dimethylphenyl)squaramidinato(2?)]bis[pentakis(2,6‐dimethylphenyl isocyanide)niobium(I)], [Nb₂(C₉H₉N)₁₀(C₃₆H₃₆N₄)] or [Nb(CNXyl)₅]₂[μ‐C₄(NXyl)₄]·xSolvent, 1 , and bis[μ‐N,N′,N′′,N′′′‐tetrakis(2,6‐dimethylphenyl)squaramidinato(2?)]bis[tetrakis(2,6‐dimethylphenyl isocyanide)niobium(I)] tetrahydrofuran trisolvate, [Nb₂(C₉H₉N)₈(C₃₆H₃₆N₄)]·3C₄H₈O or [Nb(CNXyl)₄]₂[μ‐C₄(NXyl)₄]·3THF (THF = tetrahydrofuran), 2 . Each contains Nb^I bound to either five or four terminal isocyanides, respectively, and to an unprecedented bridging tetraarylsquaramidinate(2?) unit, coordinated as a bidentate ligand to each niobium center, symmetrically due to the crystallographic inversion center that coincides with the centroid of the central C₄ unit. Thus, in the presence of CNXyl, the bis(mesitylene)niobium(0) is oxidized to niobium(I), resulting in the facile loss of both mesitylene groups and the reductive coupling of two CNXyl groups per niobium to provide the first examples of tetraarylsquaramidinate(2?) ligands, [cyclo‐C₄N₄Ar₄]^2?, coordinated to metals. In contrast, bis(mesitylene)niobium(0) reacts with the more crowded 2,6‐diisopropylphenyl isocyanide (CNDipp) to afford the paramagnetic monomer hexakis(2,6‐diisopropylphenyl isocyanide)niobium(0), [Nb(C₁₃H₁₇N)₆] or Nb(CNDipp)₆, 3 , the first zero‐valent niobium isocyanide analog of the highly unstable Nb(CO)₆, which is presently only known to exist in an argon matrix at 4.2 K.     

Platinum Complexes of a Borane‐Appended Analogue of 1,1′‐Bis(diphenylphosphino)ferrocene: Flexible Borane Coordination Modes and in situ Vinylborane Formation

A bis(phosphine)borane ambiphilic ligand, [Fe(η⁵‐C₅H₄PPh₂)(η⁵‐C₅H₄PtBu{C₆H₄(BPh₂)‐ortho})] (FcPPB), in which the borane occupies a terminal position, was prepared. Reaction of FcPPB with tris(norbornene)platinum(0) provided [Pt(FcPPB)] ( 1 ) in which the arylborane is η³BCC‐coordinated. Subsequent reaction with CO and CNXyl (Xyl=2,6‐dimethylphenyl) afforded [PtL(FcPPB)] {L=CO ( 2 ) and CNXyl ( 3 )} featuring η²BC‐ and η¹B‐arylborane coordination modes, respectively. Reaction of 1 or 2 with H₂ yielded [PtH(μ‐H)(FcPPB)] in which the borane is bound to a hydride ligand on platinum. Addition of PhC₂H to [Pt(FcPPB)] afforded [Pt(C₂Ph)(μ‐H)(FcPPB)] ( 5 ), which rapidly converted to [Pt(FcPPB′)] ( 6 ; FcPPB′=[Fe(η⁵‐C₅H₄PPh₂)(η⁵‐C₅H₄PtBu{C₆H₄(BPh‐CPh=CHPh‐Z)‐ortho}]) in which the newly formed vinylborane is η³BCC‐coordinated. Unlike arylborane complex 1 , vinylborane complex 6 does not react with CO, CNXyl, H₂ or HC₂Ph at room temperature.     

Tantalum isocyanide complexes: TaI(CNDipp)6 (Dipp is 2,6‐diisopropylphenyl) and ionic [Ta(CNDipp)7][Ta(CNDipp)6], a formal disproportionation product of the 17‐electron Ta0 metalloradical Ta(CNDipp)6

Treatment of tetraethylammonium hexacarbonyltantalate, [Et₄N][Ta(CO)₆], with 1.1 equivalents of molecular iodine (I₂) in tetrahydrofuran (THF) at 200 K, followed by the addition of 6.0 equivalents of 2,6‐diisopropylphenyl isocyanide (CNDipp) and slow warming to 293 K over a 24 h period gave the tantalum(I) iodide derivative hexakis(2,6‐diisopropylphenyl isocyanide‐κC)iodidotantalum(I), [TaI(C₁₃H₁₇N)₆] or TaI(CNDipp)₆, 1 . Recrystallization of this substance from pentane provided deep‐red nearly black parallelepipeds of the product, which was characterized by single‐crystal X‐ray diffraction. Addition of 1 in THF at 200 K to a suspension of an excess (5.8 equivalents) of caesium graphite (CsC₈), followed by warming, filtration, and solvent removal, afforded a dark‐green oily solid of unknown composition, from which several red–brown rhombohedral plates of the ditantalum salt heptakis(2,6‐diisopropylphenyl isocyanide‐κC)tantalum hexakis(2,6‐diisopropylphenyl isocyanide‐κC)tantalate, [Ta(C₁₃H₁₇N)₇][Ta(C₁₃H₁₇N)₆] or [Ta(CNDipp)₇][Ta(CNDipp)₆], 2 , were harvested. Salt 2 is a unique substance, as it is the only known example of a salt containing a homoleptic cation, [ML_x]⁺, and a homoleptic anion, [ML_y]^?, with the same transition metal and π‐acceptor ligand L. In solution, 2 undergoes full comproportionation to afford the recently reported 17‐electron paramagnetic zerovalent tantalum complex Ta(CNDipp)₆, the only known isolable TaL₆ complex of Ta⁰.     

Formation of Homo- and Heteronuclear Platinum(II) and Palladium(II) Carbene Complexes in the Reactions of Coordinated Isocyanides with Aminothiazaheterocycles

The reaction of 5-(trifluoromethyl)-1,3,4-thiadiazol-2-amine with cis-dichlorobis(2,6-dimethylphenyl isocyanide)platinum(II) (cis-[PtCl₂(CNXyl)₂], Xyl = 2,6-Me₂C₆H₃) gave platinum(II) monocarbene complex whose deprotonation with an organic base generated a nucleophilic species capable of reacting with palladium(II) and platinum(II) bis(isocyanide) complexes to afford homo- and heteronuclear isocyanide/carbene structures.     

Reactivity of Cationic Agostic and Carbene Structures Derived from Platinum(II) Metallacycles

This paper describes the formation of new platinacyclic complexes derived from the phosphine ligands PiPr₂Xyl, PMeXyl₂, and PMe₂Ar (Xyl=2,6‐Me₂C₆H₃ and Ar=2,6‐(2,6‐Me₂C₆H₃)₂‐C₆H₃) as well as reactivity studies of the trans‐[Pt(C^P)₂] bis‐metallacyclic complex 1 a derived from PiPr₂Xyl. Protonation of compound 1 a with [H(OEt₂)₂][BAr_F] (BAr_F=B[3,5‐(CF₃)₂C₆H₃]₄) forms a cationic δ‐agostic structure 4 a , whereas α‐hydride abstraction employing [Ph₃C][PF₆] produces a cationic platinum carbene trans‐[Pt{PiPr₂(2,6‐CH(Me)C₆H₃}{PiPr₂(2,6‐CH₂(Me)C₆H₃}][PF₆] ( 8 ). Compounds 4 a and 8 react with H₂ to yield the same 1:3 equilibrium mixture of 4 a and trans‐[PtH(PiPr₂Xyl)₂][BAr_F] ( 6 ), in which one of the phosphine ligands participates in a δ‐agostic interaction. DFT calculations reveal that H₂ activation by 8 occurs at the highly electrophilic alkylidene terminus with no participation of the metal. The two compounds 4 a and 8 experience C–C coupling reactions of a different nature. Thus, 4 a gives rise to complex trans‐[PtH{(E)‐1,2‐bis(2‐(PiPr₂)‐3‐MeC₆H₃)CH?CH}] ( 7 ) that contains a tridentate diphosphine–alkene ligand, through agostic C?H oxidative cleavage and C–C reductive coupling steps, whereas the C–C coupling reaction in 8 involves classical migratory insertion of its [Pt?CH] and [Pt?CH₂] bonds promoted by platinum coordination of CO or CNXyl. The mechanisms of the C?C bond‐forming reactions have also been investigated by computational methods.     

Luminescent Benzoquinolate‐Isocyanide Platinum(II) Complexes: Effect of Pt⋅⋅⋅Pt and π⋅⋅⋅π Interactions on their Photophysical Properties

The neutral compounds [Pt(bzq)(CN)(CNR)] (R=tBu ( 1 ), Xyl ( 2 ), 2‐Np ( 3 ); bzq= benzoquinolate, Xyl=2,6‐dimethylphenyl, 2‐Np=2‐napthyl) were isolated as the pure isomers with a trans‐C_bzq,CNR configuration, as confirmed by ¹³C{¹H} NMR spectroscopy in the isotopically marked [Pt(bzq)(¹³CN)(CNR)] (R=tBu ( 1′ ), Xyl ( 2′ ), 2‐Np ( 3′ )) derivatives (δ¹³C_CN≈110 ppm; ¹J(Pt,¹³C)≈1425 Hz]. By contrast, complex [Pt(bzq)(C≡CPh)(CNXyl)] ( 4 ) with a trans‐N_bzq,CNR configuration, has been selectively isolated from [Pt(bzq)Cl(CNXyl)] (trans‐N_bzq,CNR) using Sonogashira conditions. X‐ray diffraction studies reveal that while 1 adopts a columnar‐stacked chain structure with Pt–Pt distances of 3.371(1) Å and significant π???π interactions (3.262 Å), complex 2 forms dimers supported only by short Pt???Pt (3.370(1) Å) interactions. In complex 4 the packing is directed by weak bzq???Xyl and bzq???C≡E (C, N) interactions. In solid state at room temperature, compounds 1 and 2 both show a bright red emission (?=42.1 % 1 , 57.6 % 2 ). Luminescence properties in the solid state at 77 K and concentration‐dependent emission studies in CH₂Cl₂ at 298 K and at 77 K are also reported for 1 , 1·CHCl3 , 2 , 2' , 2·CHCl3 , 3 , 4 .     

(Isocyano Group π-Hole)⋅⋅⋅[d -MII] Interactions of (Isocyanide)[MII] Complexes,in which Positively Charged Metal Centers (d8-M=Pt,Pd) Act as Nucleophiles

Inspection of the X-ray structures of the newly prepared trans-[M^II(CNXyl)₂(DAPT)₂]Cl(BF₄) (M=Pd, Pt; Xyl=2,6-Me₂C₆H₃; DAPT=4,6-diaminopyrimidine-2(1H)-thione) complexes and the appropriate Hirshfeld molecular surface analysis allowed the recognition of the previously unknown π-hole⋅⋅⋅metal interactions between a ligated isocyano group (acting as a π-hole donor) and the positively charged d⁸-Pt^II and d⁸-Pd^II metal centers (acting as nucleophiles); this is the first identification of π-hole⋅⋅⋅metal interactions with triple-bond species. Results of DFT calculations followed by the topological analysis of the electron density distribution within the framework of Bader's theory (quantum theory of atoms in molecules, QTAIM) confirmed the presence of these contacts. The electrostatic surface potential calculations indicated that π-hole⋅⋅⋅metal contacts are formed upon interaction between the electrophilic isocyano C atom (π-hole donor) and the nucleophilic d orbital of the metal centers, which act as π-hole acceptors. Available CCDC data were processed from the perspective of the π-hole⋅⋅⋅metal interactions with isocyanide ligands, and their analysis disclosed the role of metal nucleophilicity in the corresponding π-hole acceptor ability.     

Synthesis and reactivity of thiophene palladium and thiophene dipalladium complexes with unsaturated molecules

Reactions of 2,5‐dibromothiophene, 1 , with [Pd₂(dba)₃]^?dba [Pd(dba)₂; dba = dibenzylideneacetone] in the presence of N‐donor ligands such as 2,2′‐bipyridine (bpy) and 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy) give arylpalladium complexes of cis‐[2‐(5‐BrC₄H₂S)PdBrL₂], 2a, b [L₂ = bpy ( 2a ), L₂ = dtbbpy ( 2b )], and cis‐cis‐L₂PdBr[2,5‐(C₄H₂S‐)PdBr(L₂)], 3a, b [L₂ = bpy ( 3a ), L₂ = dtbbpy ( 3b )]. Treatment of cis complexes 2a, b and 3a, b with CO causes the insertion of CO into the Pd? C bond to give the aroyl derivatives of palladium complexes of cis‐[2‐(5‐BrC₄H₂S)COPdBrL₂], 4a, b [L₂ = bpy ( 4a ), L₂ = dtbbpy ( 4b )], and cis‐cis‐[(L₂)(CO)BrPdC₄H₂S‐PdBr(CO)(L₂)], 5a, b [L₂ = bpy ( 5a ) and L₂ = dtbbpy ( 5b )], respectively. Treating complexes 2a, b with 1 mole equivalent of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) gave iminoacyl complexes cis‐[2‐(5‐BrC₄H₂S)C?NXyPdBrL₂], 6a, b [L₂ = bpy ( 6a ), L₂ = dtbbpy ( 6b )], and a 3‐fold excess of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) gave triiminoacyl complexes [2‐(5‐BrC₄H₂S)(C?NXy)₃ PdBr], 7 . Cyclization reactions of 6a, b with 3 mole equivalents of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) or cyclization reaction of 7 with 1 mole equivalent of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) both gave tetraiminoacyl complexes of [2‐(5‐BrC₄H₂S)(C?NXy)₄PdBr], 8 , which was also obtained by the reaction of 1 or 2a, b with a 4‐fold excess of isocyanide XyNC with or without add Pd(dba)₂. Similarly, complexes 3a and b were also reacted with 2 mole equivalents of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) to give iminoacyl complexes cis‐cis‐[(L₂)(CNXy)BrPdC₄H₂S‐PdBr(CNXy)(L₂)], 10a, b [L₂ = bpy ( 10a ), L₂ = dtbbpy ( 10b )] and an 8‐fold excess of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) afforded tetraiminoacyl complexes of [2,5‐(C₄H₂S)(C?NXy)₈Pd₂Br₂], 11 . Complexes 2a, b and 3a, b reacted with TlOTf [(TfO = CF₃SO₃)] in CH₂Cl₂ to give 9a, b and 12a, b , respectively, in a moderate yield. Copyright © 2007 John Wiley & Sons, Ltd.     

Crystal and Molecular Structure of [2,6‐(Me2NCH2)2C6H3]2SnF2, an Intramolecularly Coordinated Diorganotin Difluoride

Single‐crystal X‐ray diffraction analysis of [2,6‐(Me₂NCH₂)₂C₆H₃]₂SnF₂ reveals that only one of the two dimethylaminomethyl groups of each pincer‐type ligands [2,6‐(CH₂NMe₂)₂C₆H₃]^? is coordinated to the tin atom at Sn‐N distances of 2.576(2) and 2.470(2) Å, inducing chirality of the latter. The tin atom exhibits a distorted octahedral trans(C,C)cis(N,N)cis(F,F) configuration. Extensive intra‐ and intermolecular C‐H···F hydrogen bonding is observed with the latter giving rise to formation of polymeric chains.     

Two isomorphous crotonatolanthanide complexes: tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)Ln]–2,6‐diaminopurine (1/2) (Ln = Dy and Ho)

The title isomorphous compounds, tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)dysprosium(III)]–2,6‐diaminopurine (1/2), [Dy₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, and tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)holmium(III)]–2,6‐diaminopurine (1/2), [Ho₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, consist of [Ln(crot)₃(H₂O)₂]₂ dimers (crot is crotonate or but‐2‐enoate; Ln is the lanthanide cation), built up around inversion centres and completed by 2,6‐diaminopurine molecules. The lanthanide cation is coordinated by three chelating crotonate units and two water molecules. One of the chelating carboxylate groups acts also in a bridging mode sharing one O atom with both cations and the final result is a pair of DyO₉ tricapped prismatic polyhedra linked to each other through a central (Dy—O)₂ loop. A feature of the structures is the existence of a complex intermolecular interaction scheme involving two sets of tightly interlinked non‐intersecting one‐dimensional structures, one of them formed by the [Dy(crot)₃(H₂O)₂]₂ dimers (running along [100] and linked by O—H...O hydrogen bonds) and the second formed by 2,6‐diaminopurine molecules (evolving along [010] linked by N—H...N hydrogen bonds).     

Molecular and Crystal Structures of Mononuclear trans‐[Fe(CN)2(tOcNC)4] and trans‐[Mn(CN)(CO)(tOcNC)4] as well as of Cyanide Bridged Coordination Polymers Derived from trans‐[M(CN)2(tOcNC)4] (M = Fe,Ru)

The octahedral complexes trans‐[Fe(CN)₂(^tOcNC)₄] and trans‐[Mn(CN)(CO)(^tOcNC)₄] are produced by the reaction of 2‐isocyano‐2,4,4‐trimethyl‐pentane (tert. octyl‐isocyanide) with the corresponding transition metal carbonyls Fe₂(CO)₉ and Mn₂(CO)₁₀. In contrast to isostructural compounds with less bulky tert.‐butylisocyanide ligands the cyanide groups in trans‐[Fe(CN)₂(^tOcNC)₄] and trans‐[Mn(CN)(CO)(^tOcNC)₄] do not act as hydrogen bond acceptors towards solvent molecules in the crystal structures. In addition, the corresponding cis‐isomers are configurationally unstable. The reaction of trans‐[Fe(CN)₂(^tOcNC)₄] and trans‐[Ru(CN)₂(^tOcNC)₄] with MnCl₂, NiCl₂ and Co(NO₃)₂ ends up in the formation of cyanide bridged coordination polymers. X‐ray structure determinations of the cobalt compounds reveal different molecular structures. Whereas the former produces highly distorted infinite polymeric chains with the nitrate anions still coordinated to the cobalt centers, the latter forms polymers with the cobalt atoms being coordinated by four ethanol molecules to which the anions are bound via hydrogen bond interactions. The coordination geometries around ruthenium and cobalt in this coordination polymer are therefore nearly perfectly octahedral and tetrahedral, respectively. Measurements of the magnetic susceptibility of the coordination polymers at different temperatures are indicative of weak antiferromagnetic coupling of the paramagnetic centers along the polymeric chains.     

A new coordination complex based on a polynitrile ligand: bis(4‐amino‐3,5‐di‐2‐pyridyl‐4H‐1,2,4‐triazole)diaquairon(II) bis(1,1,3,3‐tetracyano‐2‐methylsulfanylpropenide)

The new high‐spin iron(II) complex, [Fe(C₁₂H₁₀N₆)₂(H₂O)₂](C₈H₃N₄S)₂ or [Fe(abpt)₂(H₂O)₂](tcnsme)₂ [where abpt is 4‐amino‐3,5‐di‐2‐pyridyl‐4H‐1,2,4‐triazole and tcnsme is the 1,1,3,3‐tetracyano‐2‐methylthiopropenide anion], consists of discrete [Fe(abpt)₂(H₂O)₂]²⁺ dications, where the Fe^II ion is coordinated by two N,N′‐bidentate chelating abpt ligands in the equatorial plane and two water molecules in trans positions, generating a distorted octahedral [FeN₄O₂] environment. The cationic unit is neutralized by two polynitrile tcnsme anions, in which the C—N, C—C and C—S bond lengths indicate extensive electronic delocalization. In the crystal structure, the dications and anions are linked through O—H...N and N—H...N hydrogen bonds involving the water H atoms and those of the NH₂ groups and the N atoms of the CN groups, leading to the formation of a three‐dimensional network.     

Reactions of Cyclohexyl Isocyanide with η5‐Substituted Cyclo‐pentadienyl MoMo Triply Bonded Complexes. Crystal Structure of [Mo(CO)2(η5‐C5H4CO2CH3)]2(μ‐η2‐CNC6H11)

Reactions of one or two equiv. of cyclohexyl isocyanide in THF at room temperature with Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) gave the isocyanide coordinated Mo? Mo singly bonded complexes with functionally substituted cyclopentadienyl ligands, [Mo(CO)₂(η⁵‐C₅H₄R)]₂(μ‐η²‐CNC₆H₁₁) ( 1a , R=COCH₃; 1b , R=CO₂CH₃) and [Mo(CO)₂(η⁵‐C₅H₄R)(CNC₆H₁₁)]₂ ( 2a , R=COCH₃; 2b , R=CO₂CH₃), respectively. Complexes 1a , 1b and 2a , 2b could be more conveniently prepared by thermal decarbonylation of Mo? Mo singly bonded complexes [Mo(CO)₃(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in toluene at reflux, followed by treatment of the resulting Mo?Mo triply bonded complexes [Mo(CO)₂(η⁵‐C₅H₄R)]₂ (R=COCH₃, CO₂CH₃) in situ with cyclohexyl isocyanide. While 1a , 1b and 2a , 2b were characterized by elemental analysis and spectroscopy, 1b was further characterized by X‐ray crystallography.     

Hydrogen bonding and π–π interactions in the cocrystal salt [Fe(bpe)2(H2O)4](TCEP)2·2(bpe) [bpe is trans‐1,2‐bis(pyridin‐4‐yl)ethene and TCEP is 1,1,3,3‐tetracyano‐2‐ethoxypropenide]

The cocrystal salt tetraaquabis[trans‐1,2‐bis(pyridin‐4‐yl)ethene‐κN]iron(II) bis(1,1,3,3‐tetracyano‐2‐ethoxypropenide)–trans‐1,2‐bis(pyridin‐4‐yl)ethene (1/2), [Fe(C₁₂H₁₀N₂)₂(H₂O)₄](C₉H₅N₄O)₂·2C₁₂H₁₀N₂, is a rare example of a mononuclear Fe^II compound with trans‐1,2‐bis(pyridin‐4‐yl)ethane (bpe) ligands. The complex cation resides on a crystallographically imposed inversion center and exhibits a tetragonally distorted octahedral coordination geometry. Both the symmetry‐independent bpe ligand and the cocrystallized bpe molecule are essentially planar. The 1,1,3,3‐tetracyano‐2‐ethoxypropenide counter‐ion is nonplanar and the bond lengths are consistant with significant electron delocalization. The extended structure exhibits an extensive O—H…N hydrogen‐bonding network with layers of complex cations joined by the cocrystallized bpe. Both the coordinated and the cocrystallized bpe are involved in π–π interactions. Hirshfeld and fingerprint plots reveal the important intermolecular interactions. Density functional theory was used to estimate the strengths of the hydrogen‐bonding and π–π interactions, and suggest that the O—H…N hydrogen bonds enhance the strength of the π‐interactions by increasing the polarization of the pyridine rings.     

Homoleptic Isocyanide Metalates

Novelties and surprises in the chemistry of metal isocyanides : The synthesis and structure determination of homoleptic isocyanide metalates [M(CNXyl)_m]⁻ (M=Co, m=4; M=Mn, m=5; Xyl=2,6-Me₂C₆H₃) indicate that we need to revise our understanding of transition metal–isocyanide interactions. Further investigations will be required to determine whether these salts with isocyanide metalate ions display a chemistry as rich as that of the analogous carbonyl metalates.     

Bimetallic assemblies, [Ni(en)2]3[M(CN)6]2·3H2O (en = H2NCH2CH2NH2; M = Fe,Co)

The reaction between tris(ethyl­enedi­amine)­nickel(II) cations and hexa­cyanometallate(III) anions (M = Fe, Co) yields ordered bimetallic assemblies, catena‐poly­[[tris­(ethyl­enedi­amine)­nickel‐bis(μ‐hexa­cyano­iron‐N,N′)] trihydrate] and catena‐poly­[[tris­(ethyl­enedi­amine)­nickel‐bis(μ‐hexa­cyano­cobalt‐N,N′)] trihydrate], [{Ni(C₂H₈N₂)₂}₃{M(CN)₆}₂]·3H₂O, in which both cis and trans [Ni(en)₂] and [M(CN)₆] moieties are linked to give S‐shaped Ni–NC–M–CN–Ni–NC–M–CN–Ni units which are cross­linked to give ribbons parallel to the b axis. The two compounds are isomorphous with mean metal–ligand distances Fe—C = 1.940 (3), Co—C = 1.844 (3) and Ni—N = 2.102 (2) Å for the iron, and 2.105 (3) Å for the cobalt compound. These compounds appear to be identical with those formulated as [Ni(en)₂]₃[M(CN)₆]₂·2H₂O [Ohba, Maruona, Okawa, Enoki & Latour (1994). J. Am. Chem. Soc. 116 , 11566–11567; Ohba, Fukita & Okawa (1997). J. Chem. Soc. Dalton Trans. pp. 1733–1737] which were indexed on a smaller unit cell and described as disordered.     

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.     

Cycloheptyl‐fused NNO‐ligands as electronically modifiable supports for M(II) (M = Co,Fe) chloride precatalysts; probing performance in ethylene oligo‐/polymerization

The N,N,O‐cobalt(II), [2,3‐{C₄H₈C(NAr)}:5,6‐{C₄H₈C(O)}C₅HN]CoCl₂ (Ar = 2,6‐(CHPh₂)₂‐4‐MeC₆H₂ Co1 , 2,6‐(CHPh₂)₂‐4‐EtC₆H₂ Co2 , 2,6‐(CHPh₂)₂‐4‐ClC₆H₂ Co3 , 2,6‐(CHPh₂)₂‐4‐FC₆H₂ Co4 ) and N,N,O‐iron(II) complexes, [2,3‐{C₄H₈C(NAr)}:5,6‐{C₄H₈C(O)}C₅HN]FeCl₂ (Ar = 2,6‐(CHPh₂)₂‐4‐MeC₆H₂ Fe1 , 2,6‐(CHPh₂)₂‐4‐EtC₆H₂ Fe2 , 2,6‐(CHPh₂)₂‐4‐ClC₆H₂ Fe3 , 2,6‐(CHPh₂)₂‐4‐FC₆H₂ Fe4 ), each containing one sterically enhanced but electronically modifiable N‐2,6‐dibenzhydryl‐4‐R²‐phenyl group, have been prepared by a one‐pot template approach using α,α′‐dioxo‐2,3:5,6‐bis(pentamethylene)pyridine, the corresponding aniline along with the respective cobalt or iron salt in acetic acid. Distorted square pyramidal geometries are a feature of the molecular structures of Co1 – Co4 . Upon activation with MAO or MMAO, Co1 – Co4 show good activities (up to 2.2 × 10⁵ g mol^?1(Co) h^?1) affording short chain oligomers (C₄–C₃₀) with good α‐olefin selectivity. By contrast, Fe1 – Fe4 , in the presence of MMAO, displayed moderate activities (up 10.9 × 10⁴ g(PE) mol^?1(Fe) h^?1) for ethylene polymerization forming low‐molecular‐weight linear polymers (up to 13.0 kg mol^?1) incorporating saturated n‐propyl and i‐butyl chain ends. For both cobalt and iron, the precatalysts incorporating the more electron withdrawing 4‐R²‐substituents [Cl ( Co3 / Fe3 ), F ( Co4 / Fe4 )] deliver the best catalytic activities, while with cobalt, these types of substituents additionally broaden the oligomeric distribution. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3980–3989     

fac‐Trichloro(quinolin‐8‐ylimido‐N,N′)(triphenylphosphine‐P)rhenium(V)

The Re atom in [Re(C₉H₆N₂)Cl₃(C₁₈H₁₅P)] is octahedrally coordinated by three Cl atoms in facial positions, two N atoms from 8‐imido­quinoline (imq) and one P atom from tri­phenyl­phosphine. The Re—N(imido) distance [1.760 (9) and 1.772 (8) Å] for imq is very short and implies double‐bond character. The trans influence of the P atom is indicated. Intra‐ and intermolecular π–π interactions between the π‐rings in the complex are also observed.     

Synthesis of Mixed-Ligand Nitrileand Carbonyl–Isocyanide Complexes of Platinum(II) and Their Reaction with P-Toluenesulfonyl Hydrazide

Mixed-ligand nitrile- and carbonyl-isocyanide complexes of platinum(II) trans-[PtCl₂(NCEt)CNXyl] and trans-[PtCl₂(CO)CNXyl] (Xyl = 2,6-Me₂C₆H₃) have been prepared for the first time. The compounds have been characterized by mass spectrometry, IR and NMR spectroscopy. Reactivity of the prepared complexes towards N-nucleophiles has been studied using the reaction with p-toluenesulfonyl hydrazide as the example.