Synthesis and cytostatic activity of Pt(II) complexes of intramolecularly coordinated phosphine and stibine ligands

The intramolecularly coordinated phosphine and stibine ligands L¹PPh₂ ( 1 ), L²PPh₂ ( 2 ) and L²SbPh₂ ( 3 ) containing Y,C,Y‐chelating ligands, L¹ = 2,6‐(^tBuOCH₂)₂C₆H₄^? and L² = 2,6‐(Me₂NCH₂)₂C₆H₄^?, were prepared and characterized. The treatment of these ligands 1 , 2 , 3 with PtCl₂ yielded complexes trans‐{[2,6‐(^tBuOCH₂)₂C₆H₃]PPh₂}₂PtCl₂ (4), cis‐{[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}PtCl₂ (5), and cis‐{[2,6‐(Me₂NCH₂)₂C₆H₃]SbPh₂}PtCl₂ (6) as the result of different ability of the starting compounds 1 , 2 , 3 to complex platinum centre. Compounds 1 , 2 , 3 , 4 , 5 , 6 were characterized by ¹H, ¹³C and ³¹P NMR spectroscopy and electrospray ionization mass spectrometry, and molecular structures of 3 , 4 , 5 , 6 were determined by X‐ray diffraction analysis. The substitution reactions of complexes 4 , 5 , 6 were also studied. The reaction of 5 and 6 with NaI yielded complexes {[2,6‐(Me₂NCH₂)₂C₆H₃]PPh₂}PtI₂ ( 7 ) and {[2,6‐(Me₂NCH₂)₂C₆H₃]SbPh₂}PtI₂ ( 8 ), while the same reaction of 4 with NaI did not proceed. As the compounds 7 and 8 structurally resemble cisplatin, complex {{[2‐(Me₂NCH₂)‐6‐(Me₂NHCH₂)C₆H₃]PPh₂}PtCl₂}⁺Cl^? ( 9 ) was prepared as water‐soluble platinum complex. The cytotoxic effect of complex 9 was evaluated on human T‐lymphocytic leukemia cells MOLT‐4 (IC₅₀ = 27.6 ± 1.8 µmol l^?1) and human promyelocytic leukemia HL‐60 (IC₅₀ = 55.9 ± 4.9 µmol l^?1). Copyright © 2012 John Wiley & Sons, Ltd.     

Amidophosphine‐stabilized palladium complexes catalyse Suzuki–Miyaura cross‐couplings in aqueous media

We report a simple and efficient procedure for Suzuki–Miyaura reactions in aqueous media catalysed by amidophosphine‐stabilized palladium complexes trans‐{L³PPh₂}₂PdCl₂ ( 3 ), trans‐{L³PPhtBu}₂PdCl₂ ( 4 ), [Pd(η³‐C₃H₅)(L³PPh₂)Cl] ( 5 ) and {Pd[2‐(Me₂NCH₂)C₆H₄](L³PPh₂)Cl} ( 6 ). The acidity of the NH proton in complexes 3 , 4 , 5 , 6 plays an important role in their catalytic activity. In addition, the palladium complexes cis‐{L¹PPh₂}PdCl₂ ( 1 ) and trans‐{L²PPh₂}₂PdCl₂ ( 2 ) stabilized by phosphines containing Y,C,Y‐chelating ligands L^1,2 have also been found to be useful catalysts for Suzuki–Miyaura reactions in aqueous media. The method can be effectively applied to both activated and deactivated aryl bromides yielding high or moderate conversions. The catalytic activity of couplings performed in pure water increases when utilizing a Pd complex with more acidic NH protons. A decrease of palladium concentration from 1.0 to 0.5 mol% does not lead to a substantial loss of conversion. In addition, Pd complex 1 can be efficiently recovered using two‐phase system extraction. Copyright © 2016 John Wiley & Sons, Ltd.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXII. Die Bildung von [η2‐{tBu–P=P–SiMe3}Pt(PR3)2]aus (Me3Si)tBuP–P=P(Me)tBu2 und [η2‐{C2H4}Pt(PR3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXII. The Formation of [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂] from (Me₃Si)^tBuP–P=P(Me)^tBu₂ and [η²‐{C₂H₄}Pt(PR₃)₂] (Me₃Si)^tBuP–P = P(Me)^tBu₂ reacts with [η²‐{C₂H₄}Pt(PR₃)₂] yielding [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂]. However, there is no indication for an isomer which would be the analogue to the well known [η²‐{^tBu₂P–P}Pt(PPh₃)₂]. The syntheses and NMR data of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] and [η²‐{^tBu–P=P–SiMe₃}Pt(PMe₃)₂] as well as the results of the single crystal structure determination of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] are reported.     

Novel P‐Stereogenic PCP Pincer‐Aryl Ruthenium(II) Complexes and Their Use in the Asymmetric Hydrogen Transfer Reaction of Acetophenone

Achiral P‐donor pincer‐aryl ruthenium complexes ([RuCl(PCP)(PPh₃)]) 4c , d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3‐phenylenebis(methylene)]bis[diisopropylphosphine] ( 2c ) or [1,3‐phenylenebis(methylene)]bis[diphenylphosphine] ( 2d ) and the N‐donor pincer‐aryl complex [RuCl{2,6‐(Me₂NCH₂)₂C₆H₃}(PPh₃)], ( 3 ; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P‐donor pincer‐aryl ruthenium complexes [RuCl(P*CP*)(PPh₃)] 4a , b by reacting P‐stereogenic pincer‐arenes (S,S)‐[1,3‐phenylenebis(methylene)]bis[(alkyl)(phenyl)phosphines] 2a , b (alkyl=ⁱPr or ^tBu, P*CHP*) and the complex [RuCl{2,6‐(Me₂NCH₂)₂C₆H₃}(PPh₃)], ( 3 ; Scheme 3). The crystal structures of achiral [RuCl(equation/tex2gif-sup-3.gifPCP)(PPh₃)] 4c and of chiral (S,S)‐[RuCl(equation/tex2gif-sup-6.gifPCP)(PPh₃)] 4a were determined by X‐ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh₃)] complexes and chiral [RuCl(P*CP*)(PPh₃)] complexes were tested as catalyst in the H‐transfer reduction of acetophenone with propan‐2‐ol. With the chiral complexes, a modest enantioselectivity was obtained.     

Insights into the Intramolecular Donor Stabilisation of Organostannylene Palladium and Platinum Complexes: Syntheses,Structures and DFT Calculations

The syntheses of the transition metal complexes cis‐[(4‐tBu‐2,6‐{P(O)(OiPr)₂}₂C₆H₂SnCl)₂MX₂] ( 1 , M=Pd, X=Cl; 2 , M=Pd, X=Br; 3 , M=Pd, X=I; 4 , M=Pt, X=Cl), cis‐[{2,6‐(Me₂NCH₂)₂C₆H₃SnCl}₂MX₂] ( 5 , M=Pd, X=I; 6 , M=Pt, X=Cl), trans‐[{2,6‐(Me₂NCH₂)₂C₆H₃SnI}₂PtI₂] ( 7 ) and trans‐[(4‐tBu‐2,6‐{P(O)(OiPr)₂}₂ C₆H₂SnCl)PdI₂]₂ ( 8 ) are reported. Also reported is the serendipitous formation of the unprecedented complexes trans‐[(4‐tBu‐2,6‐{P(O)(OiPr)₂}₂C₆H₂SnCl)₂ Pt(SnCl₃)₂] ( 10 ) and [(4‐tBu‐2,6‐{P(O) (OiPr)₂}₂C₆H₂SnCl)₃Pt(SnCl₃)₂] ( 11 ). The compounds were characterised by elemental analyses, ¹H, ¹³C, ³¹P, ¹¹⁹Sn and ¹⁹⁵Pt NMR spectroscopy, single‐crystal X‐ray diffraction analysis, UV/Vis spectroscopy and, in the cases of compounds 1 , 3 and 4 , also by Mössbauer spectroscopy. All the compounds show the tin atoms in a distorted trigonal‐bipyramidal environment. The Mössbauer spectra suggest the tin atoms to be present in the oxidation state III. The kinetic lability of the complexes was studied by redistribution reactions between compounds 1 and 3 as well as between 1 and cis‐[{2,6‐(Me₂NCH₂)₂C₆H₃SnCl}₂PdCl₂]. DFT calculations provided insights into both the bonding situation of the compounds and the energy difference between the cis and trans isomers. The latter is influenced by the donor strength of the pincer‐type ligands.     

Synthesis and Characterization of m‐Terphenyl (1,3‐Diphenylbenzene) Compounds Containing Trifluoromethyl Groups

The bis(silyl)triazene compound 2,6‐(Me₃Si)₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 4 ) was synthesized by double lithiation/silylation of 2,6‐Br₂‐4‐Me‐1‐(N?N? NC₄H₈)C₆H₂ ( 1 ). Furthermore, 2,6‐bis[3,5‐(CF₃)₂‐C₆H₃]‐4‐Me‐C₆H₂‐1‐(N?N? NC₄H₈)C₆H₂ derivative 6 can be easily synthesized by a C,C‐bond formation reaction of 1 with the corresponding aryl‐Grignard reagent, i.e., 3,5‐bis[(trifluoromethyl)phenyl]magnesium bromide. Reactions of compound 4 with KI and 6 with I₂ afforded in good yields novel phenyl derivatives, 2,6‐(Me₃Si)₂‐4‐MeC₆H₂? I and 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]‐4‐MeC₆H₂? I ( 5 and 7 , resp.). On the other hand, the analogous m‐terphenyl 1,3‐diphenylbenzene compound 2,6‐bis[3,5‐(CF₃)₂? C₆H₃]C₆H₃? I ( 8 ) could be obtained in moderate yield from the reaction of (2,6‐dichlorophenyl)lithium and 2 equiv. of aryl‐Grignard reagent, followed by the reaction with I₂. Different attempts to introduce the ^tBu (Me₃C) or neophyl (PhC(Me)₂CH₂) substituents in the central ring were unsuccessful. All the compounds were fully characterized by elemental analysis, melting point, IR and NMR spectroscopy. The structure of compound 6 was corroborated by single‐crystal X‐ray diffraction measurements.     

Stabilization of an Intramolecularly Coordinated Stannylidenium Cation

The treatment of trans‐{[2, 6‐(Me₂NCH₂)₂C₆H₃]SnI}₂PtI₂ with Na(pyt) (pyt = 2‐mercaptopyridine) yielded the unprecedented complex {{[2, 6‐(Me₂NCH₂)₂C₆H₃]Sn}Pt(μ‐pyt)₂I} ( 1 ), where a Sn←N coordinated stannylidenium (LSn^II)⁺ fragment donates a to a [Pt^II(pyt)₂I]^– anion. Compound 1 was characterized by NMR spectroscopy and molecular structure was determined by X‐ray diffraction analysis. The bonding situation in 1 was analyzed by DFT studies.     

Less Is More: Three‐Coordinate C,N‐Chelated Distannynes and Digermynes

We report here the synthesis of new C,N‐chelated chlorostannylenes and germylenes L³MCl (M=Sn( 1 ), Ge ( 2 )) and L⁴MCl (M=Sn( 3 ), Ge ( 4 )) containing sterically demanding C,N‐chelating ligands L^{3, 4} (L³=[2,4‐di‐tBu‐6‐(Et₂NCH₂)C₆H₂]^?_; L⁴=[2,4‐di‐tBu‐6‐{(C₆H₃‐2′,6′‐iPr₂)N=CH}C₆H₂]^?). Reductions of 1 – 4 yielded three‐coordinate C,N‐chelated distannynes and digermynes [L^{3, 4}M ]₂ for the first time ( 5 : L³, M=Sn, 6 : L³, M=Ge, 7 : L⁴, M=Sn, 8 : L⁴, M=Ge). For comparison, the four‐coordinate distannyne [L⁵Sn]₂ ( 10 ) stabilized by N,C,N‐chelate L⁵ (L⁵=[2,6‐{(C₆H₃‐2′,6′‐Me₂)N?CH}₂C₆H₃]^?) was prepared by the reduction of chlorostannylene L⁵SnCl ( 9 ). Hence, we highlight the role of donor‐driven stabilization of tetrynes. Compounds 1 – 10 were characterized by means of elemental analysis, NMR spectroscopy, and in the case of 1 , 2 , 5 – 7 , and 10 , also by single‐crystal X‐ray diffraction analysis. The bonding situation in either three‐ or four‐coordinate distannynes 5 , 7 , and 10 was evaluated by DFT calculations. DFT calculations were also used to compare the nature of the metal–metal bond in three‐coordinate C,N‐chelating distannyne [L³Sn]₂ ( 5 ) and related digermyme [L³Ge]₂ ( 6 ).     

Synthesis and Structure of (N,)C,N‐chelated Organoantimony(III) and Bismuth(III) Cations and Isolation of Their Adducts with Ag[CB11H12]

The treatment of N,C,N‐chelated antimony(III) and bismuth(III) chlorides [C₆H₃‐2,6‐(CH=NR)₂]MCl₂ [R = tBu and M = Sb ( 1 ) or Bi ( 2 ); R = Dmp and M = Sb ( 3 ) or Bi ( 4 )] (Dmp = 2,6‐Me₂C₆H₃) with one molar equivalent of Ag[CB₁₁H₁₂] led to a smooth formation of corresponding ionic pairs {[C₆H₃‐2,6‐(CH=NR)₂]MCl}⁺[CB₁₁H₁₂]^– [R = tBu and M = Sb ( 7 ) or Bi ( 8 ), R = Dmp and M = Sb ( 9 ) or Bi ( 10 )]. Similarly, the reaction of C,N‐chelated analogues [C₆H₂‐2‐(CH=NDip)‐4,6‐(tBu)₂]MCl₂ [M = Sb ( 5 ) or Bi ( 6 ), Dip = 2′,6′‐iPr₂C₆H₃] gave compounds {[C₆H₂‐2‐(CH=NDip)‐4,6‐(tBu)₂]MCl}⁺[CB₁₁H₁₂]^– [M = Sb ( 11 ) or Bi ( 12 )]. All compounds 7 – 12 were characterized with ¹H, ¹¹B and ¹³C{¹H} NMR spectroscopy, ESI‐mass spectrometry, IR spectroscopy, and molecular structures of 7 – 9 and 12 were determined by the help of single‐crystal X‐ray diffraction analysis. In contrast, all attempts to cleave also the second M–Cl bond in 7 – 12 using another molar equivalent Ag[CB₁₁H₁₂] remained unsuccessful. Nevertheless, the reaction between 7 (or 8 ) and Ag[CB₁₁H₁₂] produced unprecedented adducts of both reagents namely {[C₆H₃‐2,6‐(CH=NtBu)₂]SbCl}₂²⁺[Ag₂(CB₁₁H₁₂)₄]^2– ( 13 ) and {[C₆H₃‐2,6‐(CH=NtBu)₂]BiCl}⁺[Ag(CB₁₁H₁₂)₂]^– ( 14 ) in a reproducible manner. The molecular structures of these sparingly soluble compounds were determined by single‐crystal X‐ray diffraction analysis.     

From Dibismuthenes to Three‐ and Two‐Coordinated Bismuthinidenes by Fine Ligand Tuning: Evidence for Aromatic BiC3N Rings through a Combined Experimental and Theoretical Study

The reduction of N,C,N‐chelated bismuth chlorides [C₆H₃‐2,6‐(CH?NR)₂]BiCl₂ [where R=tBu ( 1 ), 2′,6′‐Me₂C₆H₃ ( 2 ), or 4′‐Me₂NC₆H₄ ( 3 )] or N,C‐chelated analogues [C₆H₂‐2‐(CH?N‐2′,6′‐iPr₂C₆H₃)‐4,6‐(tBu)₂]BiCl₂ ( 4 ) and [C₆H₂‐2‐(CH₂NEt₂)‐4,6‐(tBu)₂]BiCl₂ ( 5 ) is reported. Reduction of compounds 1 – 3 gave monomeric N,C,N‐chelated bismuthinidenes [C₆H₃‐2,6‐(CH?NR)₂]Bi [where R=tBu ( 6 ), 2′,6′‐Me₂C₆H₃ ( 7 ) or 4′‐Me₂NC₆H₄ ( 8 )]. Similarly, the reduction of 4 led to the isolation of the compound [C₆H₂‐2‐(CH?N‐2′,6′‐iPr₂C₆H₃)‐4,6‐(tBu)₂]Bi ( 9 ) as an unprecedented two‐coordinated bismuthinidene that has been structurally characterized. In contrast, the dibismuthene {[C₆H₂‐2‐(CH₂NEt₂)‐4,6‐(tBu)₂]Bi}₂ ( 10 ) was obtained by the reduction of 5 . Compounds 6 – 10 were characterized by using ¹H and ¹³C NMR spectroscopy and their structures, except for 7 , were determined with the help of single‐crystal X‐ray diffraction analysis. It is clear that the structure of the reduced products (bismuthinidene versus dibismuthene) is ligand‐dependent and particularly influenced by the strength of the N→Bi intramolecular interaction(s). Therefore, a theoretical survey describing the bonding situation in the studied compounds and related bismuth(I) systems is included. Importantly, we found that the C₃NBi chelating ring in the two‐coordinated bismuthinidene 9 exhibits significant aromatic character by delocalization of the bismuth lone pair.     

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

The reaction of 2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃I (2) with Pd₂(dba)₃ produced the NCN diamine pincer complex [2,6-(2-Me₂{NCH₂}C₆H₄)₂C₆H₃PdI] (3) by an oxidative addition route. The structural analysis of ligand precursor 2 revealed a syn-conformation in the solid state. Single crystal X-ray analysis of complex 3 revealed a conventional square planar geometry about the palladium center and a global C₂ symmetric structure. Variable temperature and concentration NMR spectroscopic studies of complex 3 suggest an equilibrium between 3 and the dinuclear species [{2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃Pd}₂μ²-I]I in CDCl₃ solution. An unusual carbonate complex [{2,6-(2-{Me₂NCH₂}C₆H₄)₂C₆H₃Pd}₃μ³-CO₃]I₃ (4) was also structurally characterized as a minor product during synthesis of 3.     

Reactivity Studies of η5‐ Indenyl and η5‐Cp* Ruthenium(II) Complexes towards some Polypyridyl Ligands

The reaction of [(η⁵‐L³)Ru(PPh₃)₂Cl], where; L³ = C₉H₇ ( 1 ), C₅Me₅ (Cp*) ( 2 ) with acetonitrile in the presence of [NH₄][PF₆] yielded cationic complexes [(η⁵‐L³)Ru(PPh₃)₂(CH₃CN)][PF₆]; L³= C₉H₇ ([3]PF₆) and L³ = C₅Me₅ ([4]PF₆), respectively. Complexes [3]PF₆ and [4]PF₆ reacts with some polypyridyl ligands viz, 2,3‐bis (α‐pyridyl) pyrazine (bpp), 2,3‐bis (α‐pyridyl) quinoxaline (bpq) yielding the complexes of the formulation [(η⁵‐L³)Ru(PPh₃)(L²)]PF₆ where; L³ = C₉H₇, L² = bpp, ([5]PF₆), L³ = C₉H₇, L² = bpq, ([6]PF₆); L³ = C₅Me₅, L² = bpp, ([7]PF₆) and bpq, ([8]PF₆), respectively. However reaction of [(η⁵‐C₉H₇)Ru(PPh₃)₂(CH₃CN)][PF₆] ([3]PF₆) with the sterically demanding polypyridyl ligands, viz. 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) or tetra‐2‐pyridyl‐1,4‐pyrazine (tppz) leads to the formation of unexpected complexes [Ru(PPh₃)₂(L²)(CH₃CN)][PF₆]₂; L² = tppz ([9](PF₆)₂), tptz ([11](PF₆)₂) and [Ru(PPh₃)₂(L²)Cl][PF₆]; L² = tppz ([10]PF₆), tptz ([12]PF₆). The complexes were isolated as their hexafluorophosphate salts. They have been characterized on the basis of micro analytical and spectroscopic data. The crystal structures of the representative complexes were established by X‐ray crystallography.     

Intramolecularly Coordinated Gallium Sulfides: Suitable Single Source Precursors for GaS Thin Films

Our studies have been focused on the synthesis of N→Ga coordinated organogallium sulfides [L¹Ga(μ‐S)]₃ ( 1 ) and [L²Ga(μ‐S)]₂ ( 2 ) containing either N,C,N‐ or C,N‐chelating ligands L¹ or L² (L¹ is {2,6‐(Me₂NCH₂)₂C₆H₃}^? and L² is {2‐(Et₂NCH₂)‐4,6‐tBu₂‐C₆H₂}^?). As the result of the different ligands, compounds 1 and 2 differ mutually in their structure. To change the Ga/S ratio, unusually N→Ga coordinated organogallium tetrasulfide L¹Ga(κ²‐S₄) ( 3 ) was prepared and the unprecedented complex [{2‐[CH{(CH₂)₃CH₃}(μ‐OH)]‐6‐CH₂NMe₂}C₆H₃]GaS ( 4 ) was also isolated as the minor by‐product of the reaction. Compounds 1 – 3 were further studied as potential single‐source precursors for amorphous GaS thin film deposition by spin‐coating.     

Structural characterization of the derivatives of bis{[2,6‐(dimethylamino)methyl]phenyl} selenide with palladium(II) and mercury(II)

The intramolecularly coordinated homoleptic diorgano selenide bis{2,6‐bis[(dimethylamino)methyl]phenyl} selenide, C₂₄H₃₈N₄Se or R₂Se, where R is 2,6‐(Me₂NCH₂)₂C₆H₃, 14 , was synthesized and its ligation reactions with Pd^II and Hg^II precursors were explored. The reaction of 14 with SO₂Cl₂ and K₂PdCl₄ resulted in the formation of the meta C—H‐activated dipalladated complex {μ‐2,2′‐bis[(dimethylamino)methyl]‐4,4′‐bis[(dimethylazaniumyl)methyl]‐3,3′‐selanediyldiphenyl‐κ⁴C¹,N²:C^1′,N^2′}bis[dichloridopalladium(II)], [Pd₂Cl₄(C₂₄H₃₈N₄Se)] or [{R(H)PdCl₂}₂Se], 15 . On the other hand, when ligand 14 was reacted with HgCl₂, the reaction afforded a dimercurated selenolate complex, {μ‐bis{2,6‐bis[(dimethylamino)methyl]benzeneselanolato‐κ⁴N²,Se:Se,N⁶}‐μ‐chlorido‐bis[chloridomercury(II)], [Hg₂(C₁₂H₁₉N₂Se)Cl₃] or RSeHg₂Cl₃, 16 , where two Hg^II ions are bridged by selenolate and chloride ligands. In palladium complex 15 , there are two molecules located on crystallographic twofold axes and within each molecule the Pd moieties are related by symmetry, but there are still two independent Pd centers. Mercury complex 16 results from the cleavage of one of the Se—C bonds to form a bifurcated SeHg₂ moiety with the formal charge on the Se atom being ?1. In addition, one of the Cl ligands bridges the two Hg atoms and there are two terminal Hg—Cl bonds. Each Hg atom is in a distorted environment which can be best described as a T‐shaped base with the bridging Cl atom in an apical position, with several angles close to 90° and with one angle much larger and closer to 180°.     

Aminostannanes and aminostannylenes containing a C,N-chelated ligand

Aminotin(II and IV) compounds {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂, {2-[(CH₃)₂NCH₂]C₆H₄}₂Sn[N(H)(2,6-i-Pr-C₆H₃)]₂ and {2-[(CH₃)₂NCH₂]C₆H₄}Sn[N(2,6-i-Pr-C₆H₃)(SiMe₃)] were prepared by lithium halide elimination from tin halides and corresponding lithium complexes. [(2,6-i-Pr-C₆H₃)(H)N]Li (1) reacts with one half of molar equivalent of SnCl₂ to give {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂. The same lithium amide (1) gave with R₃SnCl corresponding aminostannanes. Further reactions of these compounds with n-butyllithium gave the starting 1 and tetraorganostannanes. {2-[(CH₃)₂NCH₂]C₆H₄}₂SnBr₂ reacts with two equivalents of 1 to {2-[(CH₃)₂NCH₂]C₆H₄}₂Sn[N(H)(2,6-i-Pr-C₆H₃)]₂. The dimeric heteroleptic stannylene {[(2,6-i-Pr-C₆H₃)(SiMe₃)N](μ₂-Cl)Sn}₂ reacts with 2-[(CH₃)₂NCH₂]C₆H₄Li to the monomeric {2-[(CH₃)₂NCH₂]C₆H₄}Sn[N(2,6-i-Pr-C₆H₃)(SiMe₃)]. The structure in the solid state and in solution and reactivity of products is also discussed. The unique decatin cluster has been isolated by hydrolysis of {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂. The structure of some compounds was also evaluated by theoretical DFT methods.     

Bis(β‐diketiminato) lanthanide amides: synthesis,structure and catalysis for the polymerization of l‐lactide and ε‐caprolactone

Treatment of the chlorides (L^2,6‐iPr2_Ph)₂LnCl (L^2,6‐iPr2_Ph = [(2,6‐ⁱPr₂C₆H₃)NC(Me)CHC(Me)N(C₆H₅)]^?) with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃) afforded the monoamides (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Y ( 1 ), Yb ( 2 )) in good yields. Anhydrous LnCl₃ reacted with 2 equiv. of NaL^2,6‐iPr2_Ph in THF, followed by treatment with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃), giving the analogues (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Sm ( 3 ), Nd ( 4 )). Two monoamido complexes stabilized by two L^2‐Me ligands, (L^2‐Me)₂LnNH(2,6‐ⁱPr₂C₆H₃) (L^2‐Me = [N(2‐MeC₆H₄)C(Me)]₂CH)^?; Ln = Y ( 5 ), Yb ( 6 )), were also synthesized by the latter route. Complexes 1 , 2 , 3 , 4 , 5 , 6 were fully characterized, including X‐ray crystal structure analyses. Complexes 1 , 2 , 3 , 4 , 5 , 6 are isostructural. The central metal in each complex is ligated by two β‐diketiminato ligands and one amido group in a distorted trigonal bipyramid. All the complexes were found to be highly active in the ring‐opening polymerization of L‐lactide (L‐LA) and ε‐caprolactone (ε‐CL) to give polymers with relatively narrow molar mass distributions. The activity depends on both the central metal and the ligand (Yb < Y < Sm ≈ Nd and L^2‐Me < L^2,6‐iPr2_Ph). Remarkably, the binary 3/benzyl alcohol (BnOH) system exhibited a striking ‘immortal’ nature and proved able to quantitatively convert 5000 equiv. of L‐LA with up to 100 equiv. of BnOH per metal initiator. All the resulting PLAs showed monomodal, narrow distributions (M_w/M_n = 1.06 ? 1.08), with molar mass (M_n) decreasing proportionally with an increasing amount of BnOH. The binary 4/BnOH system also exhibited an ‘immortal’ nature in the polymerization of ε‐CL in toluene. Copyright © 2014 John Wiley & Sons, Ltd.     

SnS and SnS2 thin films deposited using a spin‐coating technique from intramolecularly coordinated organotin sulfides

Synthesis and applications of organotin(II) sulfide ({2,6‐(Me₂NCH₂)₂C₆H₃}Sn)₂(μ‐S) ( 1 ), organotin(II) thiophenolate {2,6‐(Me₂NCH₂)₂C₆H₃}Sn(SPh) ( 2 ) and organotin(IV) heptasulfide {2,6‐(Me₂NCH₂)₂C₆H₃}₂Sn₂S₇ ( 3 ) as potential single‐source precursors (SSPs) for the deposition of SnS or SnS₂ thin films using a spin‐coating method are reported. Compounds 1 , 2 and 3 differ either by tin oxidation state or by Sn:S ratio (Sn:S = 2:1 in 1 , 1:1 in 2 and 2:7 in 3 ). It is shown that compound 1 is not a suitable SSP for thin‐film fabrication using the spin‐coating process because of its incomplete decomposition at annealing temperature. However, compounds 2 and 3 seem to be promising SSPs for spin‐coating of amorphous semiconducting thin films of SnS and SnS₂, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

The Versatile Coordination Modes of Monophosphine‐o‐Carborane in the Formation of Iridium and Rhodium Complexes: Synthesis,Reactivity, and Characterization

Monophosphine‐o‐carborane has four competitive coordination modes when it coordinates to metal centers. To explore the structural transitions driven by these competitive coordination modes, a series of monophosphine‐o‐carborane Ir,Rh complexes were synthesized and characterized. [Cp*M(Cl)₂{1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁}] (M=Ir ( 1 a ), Rh ( 1 b ); Cp*=η⁵‐C₅Me₅), [Cp*Ir(H){7‐(PPh₂)‐7,8‐C₂B₉H₁₁}] ( 2 a ), and [1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 3 a ), Rh ( 3 b )) can be all prepared directly by the reaction of 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ with dimeric complexes [(Cp*MCl₂)₂] (M=Ir, Rh) under different conditions. Compound 3 b was treated with AgOTf (OTf=CF₃SO₃^?) to afford the tetranuclear metallacarborane [Ag₂(thf)₂(OTf)₂{1‐(PPh₂)‐3‐(η⁵‐Cp*)‐3,1,2‐RhC₂B₉H₁₀}₂] ( 4 b ). The arylphosphine group in 3 a and 3 b was functionalized by elemental sulfur (1 equiv) in the presence of Et₃N to afford [1‐{(S)PPh₂}‐3‐(η⁵‐Cp*)‐3,1,2‐MC₂B₉H₁₀] (M=Ir ( 5 a ), Rh ( 5 b )). Additionally, the 1‐(PPh₂)‐1,2‐C₂B₁₀H₁₁ ligand was functionalized by elemental sulfur (2 equiv) and then treated with [(Cp*IrCl₂)₂], thus resulting in two 16‐electron complexes [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₉)] ( 6 a ) and [Cp*Ir(7‐{(S)PPh₂}‐8‐S‐9‐OCH₃‐7,8‐C₂B₉H₉)] ( 7 a ). Compound 6 a further reacted with nBuPPh₂, thereby leading to 18‐electron complex [Cp*Ir(nBuPPh₂)(7‐{(S)PPh₂}‐8‐S‐7,8‐C₂B₉H₁₀)] ( 8 a ). The influences of other factors on structural transitions or the formation of targeted compounds, including reaction temperature and solvent, were also explored.     

Ruthenium NNN complexes with a 2‐hydroxypyridylmethylene fragment for transfer hydrogenation of ketones

Four NNN tridentate ligands L₁–L₄ containing 2‐methoxypyridylmethene or 2‐hydroxypyridylmethene fragment were synthesized and introduced to ruthenium centers. When (HOC₅H₃NCH₂C₅H₃NC₅H₇N₂) (L₂) and (HOC₅H₃NCH₂C₅H₃NC₆H₆N₃) (L₄) reacted with RuCl₂(PPh₃)₃, two ruthenium chloride products Ru(L₂)(PPh₃)Cl₂ ( 1 ) and Ru(L₄)(PPh₃)Cl₂ ( 2 ) were isolated, respectively. Reactions of (MeOC₅H₃NCH₂C₅H₃NC₅H₇N₂) (L₁) and (MeOC₅H₃NCH₂C₅H₃NC₆H₆N₃) (L₃) with RuCl₂(PPh₃)₃ in the presence of NH₄PF₆ generated two dicationic complexes [Ru(L₁)₂][PF₆]₂ ( 3 ) and [Ru(L₃)₂][PF₆]₂ ( 4 ), respectively. Complex 1 reacted with CO to afford product [Ru(L₂)(PPh₃)(CO)Cl][Cl]. The catalytic activity for transfer hydrogenation of ketones was investigated. Complex 1 showed the highest activity, with a turnover frequency value of 1.44 × 10³ h^?1 for acetophenone, while complexes 3 and 4 were not active.     

Coordination behaviour of the 2‐(N,N‐dimethylaminomethyl)phenyl ligand towards the di‐t‐butylchlorotin(IV) moiety

{2‐(N,N‐Dimethylaminomethyl)phenyl}(di‐t‐butyl)tin(IV)chloride, {2‐[(CH₃)₂NCH₂]C₆H₄}Sn(t‐Bu)₂ Cl, has been prepared and characterized using NMR and crystallography. This is the first example of a triorganotin(IV) halide containing the 2‐[(CH₃)₂NCH₂]C₆H₄—group as a C,N‐chelating ligand with a weak intramolecular Sn—N interaction because of the steric hindrance of t‐butyl groups. The interatomic Sn—N distance is elongated to 2.904(14) Å and the central tin atom is distorted trigonal bipyramidal. Copyright © 2004 John Wiley & Sons, Ltd.