η4‐HBCC‐σ,π‐Borataallyl Complexes of Ruthenium Comprising an Agostic Interaction

Thermolysis of [Cp*Ru(PPh₂(CH₂)PPh₂)BH₂(L₂)] 1 (Cp*=η⁵‐C₅Me₅; L=C₇H₄NS₂), with terminal alkynes led to the formation of η⁴‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)B{R‐C=CH₂}(L)₂] ( 2 a – c ) and η²‐vinylborane complexes [Cp*Ru(R‐C=CH₂)BH(L)₂] ( 3 a – c ) ( 2 a , 3 a : R=Ph; 2 b , 3 b : R=COOCH₃; 2 c , 3 c : R=p‐CH₃‐C₆H₄; L=C₇H₄NS₂) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a – c are linked by a unique η⁴‐interaction. Conversions of 1 into 3 a – c proceed through the formation of intermediates 2 a – c . Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ‐borane complex [Cp*RuCO(μ‐H)BH₂L] 4 (L=C₇H₄NS₂) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η⁴‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)BH{R‐C=CH₂}(L)] 5 and [Cp*Ru(μ‐H)BH{HC=CH‐R}(L)] 6 (R=COOCH₃; L=C₇H₄NS₂) by Markovnikov and anti‐Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η⁴‐σ,π‐borataallyl complex [Cp*Ru(μ‐H)BH{R‐C=CH‐R}(L)] 7 (R=COOCH₃; L=C₇H₄NS₂). An agostic interaction was also found to be present in 2 a – c and 5 – 7 , which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, ¹H, ¹¹B, ¹³C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b , 3 a – c and 5 – 7 . DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds.     

Synthese,Struktur und Reaktivität von η3‐1,2‐Diphosphaallylkomplexen sowie von [{(η5‐C5H5)(CO)2W–Co(CO)3}{μ‐AsCH(SiMe3)2}(μ‐CO)]

Syntheses, Structure and Reactivity of η³‐1,2‐Diphosphaallyl Complexes and [{(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃}{μ‐AsCH(SiMe₃)₂}(μ‐CO)] Reaction of ClP=C(SiMe₂iPr)₂ ( 3 ) with Na[Mo(CO)₃(η⁵‐C₅H₅)] afforded the phosphavinylidene complex [(η⁵‐C₅H₅)(CO)₂Mo=P=C(SiMe₂iPr)₂] ( 4 ) which in situ was converted into the η¹‐1,2‐diphosphaallyl complex [η⁵‐(C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₂iPr)₂] ( 6 ) by treatment with the phosphaalkene tBuP=C(NMe₂)₂. The chloroarsanyl complexes [(η⁵‐C₅H₅)(CO)₃M–As(Cl)CH(SiMe₃)₂] [where M = Mo ( 9 ); M = W ( 10 )] resulted from the reaction of Na[M(CO)₃(η⁵‐C₅H₅)] (M = Mo, W) with Cl₂AsCH(SiMe₃)₂. The tungsten derivative 10 and Na[Co(CO)₄] underwent reaction to give the dinuclear μ‐arsinidene complex [(η⁵‐C₅H₅)(CO)₂W–Co(CO)₃{μ‐AsCH(SiMe₃)₂}(μ‐CO)] ( 11 ). Treatment of [(η⁵‐C₅H₅)(CO)₂Mo{η³‐tBuPPC(SiMe₃)₂}] ( 1 ) with an equimolar amount of ethereal HBF₄ gave rise to a 85/15 mixture of the saline complexes [(η⁵‐C₅H₅)(CO)₂Mo{η²‐tBu(H)P–P(F)CH(SiMe₃)₂}]BF₄ ( 18 ) and [Cp(CO)₂Mo{F₂PCH(SiMe₃)₂}(tBuPH₂)]BF₄ ( 19 ) by HF‐addition to the PC bond of the η³‐diphosphaallyl ligand and subsequent protonation ( 18 ) and/or scission of the PP bond by the acid ( 19 ). Consistently 19 was the sole product when 1 was allowed to react with an excess of ethereal HBF₄. The products 6 , 9 , 10 , 11 , 18 and 19 were characterized by means of spectroscopy (IR, ¹H‐, ¹³C{¹H}‐, ³¹P{¹H}‐NMR, MS). Moreover, the molecular structures of 6 , 11 and 18 were determined by X‐ray diffraction analysis.     

Stereoselectivity in Diphos Addition to Molybdenum Complex with Pyridine‐2‐thionate (pyS) and η3‐Methallyl Coordinated Ligands

The conformational isomers endo‐ and exo‐[Mo{η³‐C₃H₄(CH₃)}(η²‐pyS)(CO)(η²‐diphos)] (diphos: dppm = {bis(diphenylphosphino)methane}, 2 ; dppe = {1,2‐bis(diphenylphosphino)ethane}, 3 ) are prepared by reacting the double‐bridged pyridine‐2‐thionate (pyS) complex [Mo{η³‐C₃H₄(CH₃)}(CO)₂]₂(η¹:η²:μ‐pyS)₂, 1 with diphos in refluxing acetonitrile. Stereoselectivity of the methallyl, C₃H₄(CH₃), ligand improves the formation of the exo‐conformation of 2 and 3 . Orientations and spectroscopy of these complexes are discussed.     

Gemischte Sandwichkomplexe der 4 f‐Elemente: Enantiomerenreine Cyclooctatetraenyl‐Cyclopentadienyl‐Komplexe des Samariums und Lutetiums mit donorfunktionalisierten Cyclopentadienylliganden

Organometallic Compounds of the Lanthanides. 139 Mixed Sandwich Complexes of the 4 f Elements: Enantiomerically Pure Cyclooctatetraenyl Cyclopentadienyl Complexes of Samarium and Lutetium with Donor‐Functionalized Cyclopentadienyl Ligands The reactions of [K{(S)‐C₅H₄CH₂CH(Me)OMe}], [K{(S)‐C₅H₄CH₂CH(Me)NMe₂}] and [K{(S)‐C₅H₄CH(Ph)CH₂NMe₂}] with the cyclooctatetraenyl lanthanide chlorides [(η⁸‐C₈H₈)Ln(μ‐Cl)(THF)]₂ (Ln = Sm, Lu) yield the mixed cyclooctatetraenyl cyclopentadienyl lanthanide complexes [(η⁸‐C₈H₈)Sm{(S)‐η⁵ : η¹‐C₅H₄CH₂CH(Me)OMe}] ( 1 a ), [(η⁸‐C₈H₈)Ln{(S)‐η⁵ : η¹‐C₅H₄CH₂CH(Me)NMe₂}] (Ln = Sm ( 2 a ), Lu ( 2 b )) and [(η⁸‐C₈H₈)Ln{(S)‐η⁵ : η¹‐C₅H₄CH(Ph)CH₂NMe₂}] (Ln = Sm ( 3 a ), Lu ( 3 b )). For comparison, the achiral compounds [(η⁸‐C₈H₈)Ln{η⁵ : η¹‐C₅H₄CH₂CH₂NMe₂}] (Ln = Sm ( 4 a ), Lu ( 4 b )) are synthesized in an analogous manner. ¹H‐, ¹³C‐NMR‐, and mass spectra of all new compounds as well as the X‐ray crystal structures of 3 b and 4 b are discussed.     

Stepwise Strategy to Cyclometallated PtII Complexes with N‐Heterocyclic Carbene Ligands: A Luminescence Study on New β‐Diketonate Complexes

The imidazolium salt 3‐methyl‐1‐(naphthalen‐2‐yl)‐1H‐imidazolium iodide ( 2 ) has been treated with silver(I) oxide and [{Pt(μ‐Cl)(η³‐2‐Me‐C₃H₄)}₂] (η³‐2‐Me‐C₃H₄=η³‐2‐methylallyl) to give the intermediate N‐heterocyclic carbene complex [PtCl(η³‐2‐Me‐C₃H₄)(H$\widehat{CC}$ *‐κC*)] ( 3 ) (H$\widehat{CC}$ *‐κC*=3‐methyl‐1‐(naphthalen‐2‐yl)‐1H‐imidazol‐2‐ylidene). Compound 3 undergoes regiospecific cyclometallation at the naphthyl ring of the NHC ligand to give the five‐membered platinacycle compound [{Pt(μ‐Cl)($\widehat{CC}$ *)}₂] ( 4 ). Chlorine abstraction from 4 with β‐diketonate Tl derivatives rendered the corresponding neutral compounds [Pt($\widehat{CC}$ *)(L‐O,O′)] {L=acac (HL=acetylacetone) 5 , phacac (HL=1,3‐diphenyl‐1,3‐propanedione) 6 , hfacac (HL=hexafluoroacetylacetone) 7 }. All of the compounds ( 3 – 7 ) were fully characterized by standard spectroscopic and analytical methods. X‐ray diffraction studies were performed on 5 – 7 , revealing short Pt?Pt and π–π interactions in the solid‐state structure. The influence of the R‐substituents of the β‐diketonate ligand on the photophysical properties and the use of the most efficient emitter, 5 , as phosphor converter has also been studied.     

Activation of Molecular Hydrogen by Bis(η5,η1‐pentafulvene)‐titanium Complexes – Efficient Formation of Titanium(III)hydrides

The synthesis and crystal structures of two dinuclear titanocene hydride complexes are reported. Both complexes, namely bis(η⁵‐(di‐para‐tolylmethyl)cyclopentadienyl)titanium hydride dimer, [(η⁵‐C₂₀H₁₉)₂Ti(μ‐H)]₂ ( 2a ), and bis(η⁵‐2‐adamantylcyclopentadienyl)‐titanium hydride dimer, [(η⁵‐C₁₅H₁₉)₂Ti(μ‐H)]₂ ( 2b ), are formed via activation of molecular hydrogen by the corresponding bis(η⁵,η¹‐pentafulvene)titanium complexes 1a and 1b at ambient temperatures and pressures in high yields. The hydride complexes 2a and 2b exhibit planar [Ti₂H₂] cores and, as a result of the heterolytic cleavage of molecular hydrogen, substituted Cp Ligands were formed during the reaction.     

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.     

Molekül‐ und Kristallstruktur von Bis[chloro(μ‐phenylimido)(η5‐pentamethylcyclopentadienyl)tantal(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}2]

Molecular and Crystal Structure of Bis[chloro(μ‐phenylimido)(η⁵‐pentamethylcyclopentadienyl)tantalum(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}₂] Despite the steric hindrance of the central atom in [TaCl₂(NPh)Cp*] (Ph = C₆H₅, Cp* = η⁵‐C₅(CH₃)₅), caused by the Cp* ligand, the imido‐ligand takes a change in bond structure when this educt is reduced to the binuclear complex [{TaCl(μ‐NPh)Cp*}₂] in which tantalum is stabilized in the unusual oxidation state +4.     

Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

The half‐open rare‐earth‐metal aluminabenzene complexes [(1‐Me‐3,5‐tBu₂‐C₅H₃Al)(μ‐Me)Ln(2,4‐dtbp)] (Ln=Y, Lu) are accessible via a salt metathesis reaction employing Ln(AlMe₄)₃ and K(2,4‐dtbp). Treatment of the yttrium complex with B(C₆F₅)₃ and tBuCCH gives access to the pentafluorophenylalane complex [{1‐(C₆F₅)‐3,5‐tBu₂‐C₅H₃Al}{μ‐C₆F₅}Y{2,4‐dtbp}] and the mixed vinyl acetylide complex [(2,4‐dtbp)Y(μ‐η¹:η³‐2,4‐tBu₂‐C₅H₄)(μ‐CCtBu)AlMe₂], respectively.     

Synthesis,Reactivity and Crystal Structures of the Palladium(II) Complexes with the Pyrimidine Containing Ligand: Crystal Structures of [Pd(PPh3)(η1‐C4H3N2)(η2‐S2CNC4H8)] and [Pd(PPh3)(η1‐C4H3N2)(η2‐Tp)]

Treatment of Pd(PPh₃)₄ with 5‐bromo‐pyrimidine [C₄H₃N₂Br] in dichloromethane at ambient temperature cause the oxidative addition reaction to produce the palladium complex [Pd(PPh₃)₂(η¹‐C₄H₃N₂)(Br)], 1 , by substituting two triphenylphosphine ligands. In acetonitrile solution of 1 in refluxing temperature for 1 day, it do not undergo displacement of the triphenylphosphine ligand to form the dipalladium complex [Pd(PPh₃)Br]₂{μ,η²‐(η¹‐C₄H₃N₂)}₂, or bromide ligand to form chelating pyrimidine complex [Pd(PPh₃)₂(η²‐C₄H₃N₂)]Br. Complex 1 reacted with bidentate ligand, NH₄S₂CNC₄H₈, and tridentate ligand, KTp {Tp = tris(pyrazoyl‐1‐yl)borate}, to obtain the η²‐dithiocarbamate η¹‐pyrimidine complex [Pd(PPh₃)(η¹‐C₄H₃N₂)(η²‐S₂CNC₄H₈)], 4 and η²‐Tp η¹‐pyrimidine complex [Pd(PPh₃)(η¹‐C₄H₃N₂)(η²‐Tp)], 5 , respectively. Complexes 4 and 5 are characterized by X‐ray diffraction analyses.     

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.     

Chemistry of N,S‐Heterocyclic Carbene and Metallaboratrane Complexes: A New η3‐BCC‐Borataallyl Complex

A high‐yielding synthetic route for the preparation of group 9 metallaboratrane complexes [Cp*MBH(L)₂], 1 and 2 ( 1 , M=Rh, 2 , M=Ir; L=C₇H₄NS₂) has been developed using [{Cp*MCl₂}₂] as precursor. This method also permitted the synthesis of an Rh–N,S‐heterocyclic carbene complex, [(Cp*Rh)(L₂)(1‐benzothiazol‐2‐ylidene)] ( 3 ; L=C₇H₄NS₂) in good yield. The reaction of compound 3 with neutral borane reagents led to the isolation of a novel borataallyl complex [Cp*Rh(L)₂B{CH₂C(CO₂Me)}] ( 4 ; L=C₇H₄NS₂). Compound 4 features a rare η³‐interaction between rhodium and the B‐C‐C unit of a vinylborane moiety. Furthermore, with the objective of generating metallaboratranes of other early and late transition metals through a transmetallation approach, reactions of rhoda‐ and irida‐boratrane complexes with metal carbonyl compounds were carried out. Although the objective of isolating such complexes was not achieved, several interesting mixed‐metal complexes [{Cp*Rh}{Re(CO)₃}(C₇H₄NS₂)₃] ( 5 ), [Cp*Rh{Fe₂(CO)₆}(μ‐CO)S] ( 6 ), and [Cp*RhBH(L)₂W(CO)₅] ( 7 ; L=C₇H₄NS₂) have been isolated. All of the new compounds have been characterized in solution by mass spectrometry, IR spectroscopy, and ¹H, ¹¹B, and ¹³C NMR spectroscopies, and the structural types of 4 – 7 have been unequivocally established by crystallographic analysis.     

Insertions‐ und Substitutionsreaktion von Ameisensäuremethylester mit [Cp′2ZrCl(PHTipp)] – Molekülstruktur von meso‐trans‐[Cp′2ZrCl{OCH(PHTipp)2}] (Cp′ = η5‐C5MeH4, Tipp = 2,4,6‐Pri3C6H2)

Insertion and Substitution Reaction of Methyl Formate with [Cp′₂ZrCl(PHTipp)] – Molecular Structure of meso‐trans ‐[Cp′₂ZrCl{OCH(PHTipp)₂}] (Cp′ = η⁵‐C₅MeH₄, Tipp = 2,4,6‐Prⁱ₃C₆H₂) [Cp′₂ZrCl(PHTipp)] ( 1 ) (Cp′ = η⁵‐C₅MeH₄, Tipp = 2,4,6‐Prⁱ₃C₆H₂) reacts with methyl formate with insertion and substitution to give [Cp′₂ZrCl{OCH(PHTipp)₂}] ( 2 ). 2 was characterized spectroscopically (¹H, ³¹P NMR, IR, MS) and by X‐ray structure determination. Only the meso‐trans isomer is present in the solid state.     

Stabilization of a Silaaldehyde by its η2 Coordination to Tungsten

Treatment of pyridine‐stabilized silylene complexes [(η⁵‐C₅Me₄R)(CO)₂(H)W?SiH(py)(Tsi)] (R=Me, Et; py=pyridine; Tsi=C(SiMe₃)₃) with an N‐heterocyclic carbene ^MeIⁱPr (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) caused deprotonation to afford anionic silylene complexes [(η⁵‐C₅Me₄R)(CO)₂W?SiH(Tsi)][H^MeIⁱPr] (R=Me ( 1‐Me ); R=Et ( 1‐Et )). Subsequent oxidation of 1‐Me and 1‐Et with pyridine‐N‐oxide (1 equiv) gave anionic η²‐silaaldehydetungsten complexes [(η⁵‐C₅Me₄R)(CO)₂W{η²‐O?SiH(Tsi)}][H^MeIⁱPr] (R=Me ( 2‐Me ); R=Et ( 2‐Et )). The formation of an unprecedented W‐Si‐O three‐membered ring was confirmed by X‐ray crystal structure analysis.     

Synthese,Struktur und Reaktivität von η1und η3‐Allyl‐Rhenium‐Carbonylen

Synthesis, Structure, and Reactivity of η¹‐ and η³‐Allyl Rhenium Carbonyls In (η³‐C₃H₅)Re(CO)₄ one CO ligand can be substituted by PPh₃, pyridine, isocyanide and benzonitrile. With 1,2‐bis(diphenylphosphino)ethylene, 1,1′‐bis(diphenylphosphino)ferrocene and 1,2‐bis(4‐pyridyl)ethane dinuclear ligand bridged complexes are obtained. The η³‐η¹ conversion of the allyl ligand occurs on reaction of (η³‐C₃H₅)Re(CO)₄ with the bidendate ligands 1,2‐bis(diphenylphosphino)ethane and 1,3‐bis(diphenylphosphino)propane and with 2,2′‐bipyridine (L–L) which gives the complexes (η¹‐C₃H₅)Re(CO)₃(L–L). By reaction of (η³‐C₃H₅)Re(CO)₄ with bis(diphenylphosphino)methane the allyl group is protonated and under elemination of propene the complex (OC)₃Re(Ph₂PCHPPh₂)(η¹‐Ph₂PCH₂PPh₂) ( 19 ) with a diphosphinomethanide ligand is formed. On heating solutions of (η³‐C₃H₅)Re(CO)₄ and (η³‐C₃H₅)Re(CO)₃(CN‐2,5‐Me₂C₆H₃) ( 5 ) in methanol the methoxy bridged compounds Re₄(CO)₁₂(OH)(OMe)₃ and Re₂(CO)₄(CN‐2,5‐Me₂C₆H₃)₄(μ‐OMe)₂ ( 20 ) were isolated. The crystal structures of (η³‐C₃H₅)Re(CO)₃(CNCH₂SiMe₃) ( 4 ), [(η³‐C₃H₅)(OC)₃Re]₂‐ (μ‐bis‐(diphenylphosphino)ferrocene) ( 8 ), (η¹‐C₃H₅)Re(CO)₃‐ (bpy) ( 14 ), of 19 , 20 and of (OC)₃Re‐[Ph₂P(CH₂)₃PPh₂]Cl ( 16 ) were determined by X‐ray diffraction.     

Reactions of Dienes with a Mo(0) Complex with Tetraphosphine Coligand [Mo(P4)(Ph2PCH2CH2PPh2)] (P4 = Meso‐o‐C6H4(PPhCH2CH2PPh2)2)

Reaction of tetraphosphine complex [Mo(κ⁴‐P4)(Ph₂PCH₂CH₂PPh₂)] (1; P4 = meso‐o‐C₆H₄‐(PPhCH₂CH₂PPh₂)₂) with E‐1,3‐pentadiene in toluene at 60 °C gave the η⁴‐diene complex [Mo(η⁴‐E‐1,3‐pentadiene)(κ⁴‐P4)] (2), which is present as a mixture of two isomers due to the orientation of the Me group in the diene ligand. Treatment of 1 with Z‐1,3‐pentadien also resulted in the formation of 2 as the sole product after heating the reaction mixture at 90 °C. Whereas the reaction of 1 with 1,3‐cyclohexadiene at 60 °C afforded the η⁴‐diene complex [Mo(η⁴‐cyclohexadiene)(κ⁴‐P4)] (6), that with cyclopentadiene led to the C‐H bond scission product [η⁵‐C₅H₅)MoH(κ³‐P4)] (7). Detailed structures were determined by X‐ray crystallography for 2, 6,and 7, and fluxional feature of 6 in solution was clarified based on the VT‐NMR studies.     

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 .     

[μ‐1κ2O,O′:2(η5)‐Cyclopentadienylcarboxylato][2(η5)‐diphenylphosphinocyclopentadienyl]bis[1,1(η5)‐tetramethylcyclopentadienyl]iron(II)titanium(III)

Reacting stoichiometric amounts of 1‐(diphenylphosphino)ferrocene­carboxylic acid and [Ti(η⁵‐C₅HMe₄)₂(η²‐Me₃SiC[triple‐bond]CSiMe₃)] produced the title carboxyl­atotitanocene complex, [{μ‐1κ²O,O′:2(η⁵)‐C₅H₄CO₂}{2(η⁵)‐C₅H₄P(C₆H₅)₂}{1(η⁵)‐C₅H(CH₃)₄}₂Fe^IITi^III] or [FeTi(C₉H₁₃)₂(C₆H₄O₂)(C₁₇H₁₄P)]. The angle subtended by the Ti/O/O′ plane, where O and O′ are the donor atoms of the κ²‐carboxy­late group, and the plane of the carboxyl‐substituted ferrocene cyclo­penta­dienyl is 24.93 (6)°.     

η2(π)‐Coordination of a Bis‐Phosphonio‐Benzophospholide Cation: A Novel Complexation Mode for Unsaturated Phosphorus Heterocycles

The bis‐phosphonio‐benzo[c]phospholide tetraphenylborate 4 [BPh₄] reacts with CpCo(C₂H₄)₂ to form a chelate complex [Co(η⁵–Cp)(κ²P,η²(P=C) –4 )][BPh₄] ( 6 [BPh₄]) which was characterized by means of spectroscopic techniques and a single crystal X‐ray diffraction study. The observed η²(π)‐coordination of the benzophospholide moiety in the cation 6 is highly unusual for aromatic phosphorus heterocycles. The structural data suggest a pronounced coordination‐induced localization of π‐electrons in the condensed ring system.     

Synthesis and Platinum Complexes of an Alane‐Appended 1,1′‐Bis(phosphino)ferrocene Ligand

An aryldimethylalane‐appended analogue of 1,1′‐bis(diphenylphosphino)ferrocene, FcPPAl, was prepared, and reaction with [Pt(nb)₃] (nb=norbornene) afforded [Pt(η²‐nb)(FcPPAl)] ( 1 ). Heating a solution of 1 to 80 °C resulted in crystallization of [{Pt(FcPPAl)}₂] ( 2 ), whereas treatment of 1 with C₂H₄, C₂Ph₂, H₂, or CO provided [PtL(FcPPAl)] [L=C₂H₄ ( 3 ), C₂Ph₂ ( 4 )], [PtH₂(FcPPAl)] ( 5 ), and [Pt(CO)(FcPPAl)] ( 6 ). In all complexes, the FcPPAl ligand is coordinated through both phosphines and the alane. Whereas 2 adopts a T‐shaped geometry at platinum, 3 – 5 are square‐pyramidal, and 6 is distorted square‐planar. The hydride and carbonyl complexes feature unusual multicenter bonding involving platinum, aluminum, and a hydride or carbonyl ligand.