Crystallographic report: Dichloro(β‐methoxycarbonylethyl)tin(IV) isopropylxanthate

The Sn atom in CH₃OCOCH₂CH₂SnCl₂[S₂COCH(CH₃)₂] adopts a distorted octahedral geometry via the bidentate xanthate ligand and intramolecular carbonyl coordination. Copyright © 2005 John Wiley & Sons, Ltd.     

Ligand exchange reaction of Zn(II)-acetylacetonate complex with 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid

Ligand exchange reaction of Zn(II)-acetylacetonate complex (Zn-acac₂) with 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (H₂TPPS) has been investigated spectrophotometrically and radiometrically. The exchange reaction was observed by spectral change from H₂TPPS to Zn-TPPS or activity of⁶⁵Zn(acac)₂ extracted into the chloroform phase. The 2nd order rate constants (k ₂) for the exchange reaction at 70 °C and at pH 7.8 were found to be 32.8±2.3 and 31.2±3.2 M^–1·s^–1 from the spectrometric and radiotracer experiments, respectively. For the direct complexation of Zn(II) with H₂TPPS, a similar 2nd order rate constant (k=32.4±4.7 M^–1·s^–1) was obtained as that in the ligand exchange reaction. The activation energies (E) for the exchange and the formation of Zn-TPPS were found to be 69.3±0.2 and 69.4±0.2 kJ·mol^–1, respectively, in the temperature range from 40 to 70 °C.     

Ligand Substitution Reactions on Aquapentachloro‐ and Hexachloroplatinic Acid — Synthesis and Characterization of Tetrachloroplatinum(IV) Complexes with Heterocyclic N,N Donors

Reactions of aquapentachloroplatinic acid, (H₃O)[PtCl₅(H₂O)]·2(18C6)·6H₂O ( 1 ) (18C6 = 18‐crown‐6), and H₂[PtCl₆]·6H₂O ( 2 ) with heterocyclic N, N donors (2, 2′‐bipyridine, bpy; 4, 4′‐di‐tert‐butyl‐2, 2′‐bipyridine, tBu₂bpy; 1, 10‐phenanthroline, phen; 4, 7‐diphenyl‐1, 10‐phenanthroline, Ph₂phen; 2, 2′‐bipyrimidine, bpym) afforded with ligand substitution platinum(IV) complexes [PtCl₄(N∩N)] (N∩N = bpy, 3a ; tBu₂bpy, 3b ; Ph₂phen, 5 ; bpym, 7 ) and/or with protonation of N, N donor yielding (R₂phenH)₂[PtCl₆] (R = H, 4a ; Ph, 4b ) and (bpymH)⁺ ( 8 ). With UV irradiation Ph₂phen and bpym reacted with reduction yielding platinum(II) complexes [PtCl₂(N∩N)] (N∩N = Ph₂phen, 6 ; bpym, 9 ). Identities of all complexes were established by microanalysis as well as by NMR (¹H, ¹³C, ¹⁹⁵Pt) and IR spectroscopic investigations. Molecular structures of [PtCl₄(bpym)]·MeOH ( 7 ) and [PtCl₂(Ph₂phen)] ( 6 ) were determined by X‐ray diffraction analyses. Differences in reactivity of bpy/bpym and phen ligands are discussed in terms of calculated structures of complexes [PtCl₅(N∩N)]^— with monodentately bound N, N ligands (N∩N = bpy, 10a ; phen, 10b ; bpym, 10c ).     

Organotin adducts with pyrimidinethione: crystal structure of dimethyldi(pyrimidine‐2‐thiolato)tin(IV) and diphenyldi(pyrimidine‐2‐thiolato)tin(IV)

The complexes dimethyldi(pyrimidine‐2‐thiolato)tin(IV) ( 1 ) and diphenyldi(pyrimidine‐2‐thiolato)tin(IV) ( 2 ) have been structurally ­characterized by means of X‐ray crystallography. Complex 1 exhibits strong π–π stacking interactions and adduct 2 is self‐assembled via intermolecular hydrogen bonds, C H–π and π–π stacking interactions. Partial solvolysis occurs in organic solvents for 1 and 2 . Copyright © 2000 John Wiley & Sons, Ltd.     

Diiodobis(4‐methylpentan‐2‐onato‐C4,O)tin(IV): a comparison with diiodobis(3‐methoxy‐3‐oxopropyl‐C,O)tin(IV)

The title compound, [SnI₂(C₆H₁₁O)₂], contains a six‐coordinate tin centre as a consequence of intramolecular Sn—O interactions. The Sn—O bond lengths range between 2.428 (4) and 2.439 (4) Å.     

Chloro­di­methyl(N‐methyl­pyrrolidin­one)­tin(IV)‐μ‐chloro‐di­chloro­di­methyl­tin(IV)

The synthesis and the X‐ray structural analysis of the title compound, μ‐chloro‐1:2κ²Cl‐tri­chloro‐1κCl,2κ²Cl‐tetra­methyl‐1κ²C,2κ²C‐(N‐methyl­pyrrolidin‐2‐one)‐1κO‐ditin(IV), [Sn₂Cl₄(CH₃)₄(C₅H₉NO)], are described. The title compound is found to exhibit a distorted trigonal–bipyramidal geometry at both Sn^IV atoms. The Sn—Cl—Sn angle involving the bridging chlorine ligand is 135.56 (5)°, with the Sn—Cl bond lengths being 2.5704 (13) and 3.1159 (13) Å.     

Crystallographic report: L‐(−)‐Dichloro(β‐menthoxycarbonylethyl)tin N,N‐diethyldithiocarbamate

The tin atom in the title compound adopts a distorted octahedral geometry within a CCl₂OS₂ donor set. Copyright © 2005 John Wiley & Sons, Ltd.     

Bromo­di­methyl(N‐methyl­pyrrolidin‐2‐one‐O)­tin(IV)‐di‐μ‐bromo‐bromo­di­methyl­tin(IV)

The preparation and X‐ray analysis of the title compound, [Sn₂Br₄(CH₃)₄(C₅H₉NO)], are described. The compound contains two Sn atoms in the asymmetric unit, that complexed by N‐methyl­pyrrolidin‐2‐one being hexacoordinated (a), the other exhibiting pentacoordination (b). The most important features are three different Sn—Br bond lengths at both Sn atoms with the following values: (a) 2.5060 (9), 2.7152 (10) and 3.7118 (10) Å; (b) 2.5084 (10), 2.5279 (9) and 3.5841 (10) Å.     

β -Cyclodextrin-Mediated Regioselective Hydrolysis of 5,10,15,20-tetrakis[2,4-bis(pivaloyloxy)phenyl]-21H,23H -porphine

The four peripheral ester moieties of the title compound 5 are regioselectively hydrolyzed under mild conditions in the presence of β -cyclodextrin ( 10 ), providing a new entry to tetraphenylporphyrin derivatives with differently substituted Ph groups in the meso-positions. UV, ¹H-NMR and mass spectroscopy of the inclusion complex 9 of 2,6-O-dimethyl-β-cyclodextrin ( 12 ) and 5 indicate a stoichiometry of 2:1 for 10/5 . Moreover, calculations confirm NOE experiments consistent with the fact that the cyclodextrins 10 and 12 approach the Ph groups of the porphyrin with the small opening of the cavity (primary face).     

Preparation and in vitro investigations of triphenyl[ω‐(tetrahydro‐2H‐pyran‐2‐yloxy)alkyl]tin(IV) compounds

The reaction of SnPh₃Li with X(CH₂)_n O–THP (THP = tetrahydro‐2H ‐pyran‐2‐yl; n  = 3, 4, 6, 8, 11; X = Cl, Br) afforded organotin(IV) compounds with the general formula Ph₃Sn(CH₂)_n O–THP ( 1 – 5 ). The tetraorganotin(IV) compounds were characterized using multinuclear NMR and infrared spectroscopies and high‐resolution mass spectrometry. Anticancer activity of the synthesized compounds was tested in vitro against the A2780 (ovarian), A549 (lung), HeLa (adenocarcinoma) and SW480 (colon) tumour cell lines with SRB assay. The in vitro investigations revealed that when a shorter chain was present a higher activity was achieved; however compounds 1 – 5 were found to be less active than cisplatin. In addition, the most active compound, 1 , enters A2780 cells and causes apoptosis by triggering both intrinsic and extrinsic caspase pathways.     

Chloro­(μ‐6‐methyl­pyridine‐2‐carboxyl­ato)bis­(6‐methyl­pyridine‐2‐carboxyl­ato)triphenyl­chromium(III)­tin(IV) chloro­triphenyl­tin(IV)

The title compound, [CrSn(C₆H₅)₃(C₇H₆NO₂)₃Cl][Sn(C₆H₅)₃Cl(CH₄O)], was obtained from the reaction of Ph₃SnCl with the complex [Cr(C₇H₆NO₂)₃] in methanol. The structure contains [Ph₃SnCl(MeOH)] (A) and [Ph₃SnClCr(C₇H₆NO₂)₃] (B) mol­ecules. In mol­ecule A, the Sn atom of Ph₃SnCl is coordinated by one methanol mol­ecule. In mol­ecule B, the Sn atom of Ph₃SnCl is coordinated by one carboxyl­ate O atom of [Cr(C₇H₆NO₂)₃]. Mol­ecules A and B are connected through an O—H⋯O hydrogen bond between a carboxyl­ate O atom and the methanol OH group. Weak C—H⋯Cl inter­actions and O—H⋯O hydrogen bonds extend the components of (I) into a two‐dimensional network.     

Chlorotris(2,4,6‐trimethylphenyl)tin(IV) and its ethanol hemisolvate

Chloro­tris(2,4,6‐tri­methyl­phenyl)­tin(IV), crystallizes from ethanol as solvent‐free needles, [Sn(C₉H₁₁)₃Cl], (I), and as the hemisolvate, [Sn(C₉H₁₁)₃Cl]·0.5C₂H₆O, (II). The asymmetric unit in (I) has three independent mol­ecules, whereas in (II), there are two [Sn(C₉H₁₁)₃Cl] mol­ecules together with one ethanol molecule. In the unit cell of (II), the ethanol mol­ecules lie in channels between stacks of (Mes)₃SnCl mol­ecules (Mes is 2,4,6‐tri­methyl­phenyl) and each ethanol mol­ecule is disordered (0.50:0.50) over two positions. A comparison of the structures of the title compounds and other (Mes)₃SnX (X = F, Br or I) systems with those of the tri­phenyl­tin analogues shows that the steric requirements of the o‐CH₃ groups are met by a flattening of the SnC₃ skeleton and increases in the average Sn—X and Sn—C values. Comparing Sn—X data for (Mes)₃SnX (X = F, Cl, Br or I) systems with values for the tris(o‐methoxy­phenyl)­tin analogues suggests that the Sn—F distance of 1.961 Å in (Mes)₃SnF may well be characteristic of sterically unhindered four‐coordinate Ar₃SnF systems.     

Sterically Less‐Hindered Half‐Titanocene(IV) Phenoxides: Ancillary‐Ligand Effect on Mono‐, Bis‐, and Tris(2‐Alkyl‐/arylphenoxy) Titanium(IV) Chloride Complexes

A series of mono‐, bis‐, and tris(phenoxy)–titanium(IV) chlorides of the type [Cp*Ti(2‐R? PhO)_nCl_3?n] (n=1–3; Cp*=pentamethylcyclopentadienyl) was prepared, in which R=Me, iPr, tBu, and Ph. The formation of each mono‐, bis‐, and tris(2‐alkyl‐/arylphenoxy) series was authenticated by structural studies on representative examples of the phenyl series including [Cp*Ti(2‐Ph? PhO)Cl₂] ( 1 PhCl2 ), [Cp*Ti(2‐Ph? PhO)₂Cl] ( 2 PhCl ), and [Cp*Ti(2‐Ph? PhO)₃] ( 3 Ph ). The metal‐coordination geometry of each compound is best described as pseudotetrahedral with the Cp* ring and the 2‐Ph? PhO and chloride ligands occupying three leg positions in a piano‐stool geometry. The mean Ti? O distances, observed with an increasing number of 2‐Ph? PhO groups, are 1.784(3), 1.802(4), and 1.799(3) Å for 1 PhCl2 , 2 PhCl , and 3 Ph , respectively. All four alkyl/aryl series with Me, iPr, tBu, and Ph substituents were tested for ethylene homopolymerization after activation with Ph₃C⁺[B(C₆F₅)₄]^? and modified methyaluminoxane (7% aluminum in isopar E; mMAO‐7) at 140 °C. The phenyl series showed much higher catalytic activity, which ranged from 43.2 and 65.4 kg (mmol of Ti?h)^?1, than the Me, iPr, and tBu series (19.2 and 36.6 kg (mmol of Ti?h)^?1). Among the phenyl series, the bis(phenoxide) complex of 2 PhCl showed the highest activity of 65.4 kg (mmol of Ti?h)^?1. Therefore, the catalyst precursors of the phenyl series were examined by treating them with a variety of alkylating reagents, such as trimethylaluminum (TMA), triisobutylaluminum (TIBA), and methylaluminoxane (MAO). In all cases, 2 PhCl produced the most catalytically active alkylated species, [Cp*Ti(2‐Ph? PhO)MeCl]. This enhancement was further supported by DFT calculations based on the simplified model with TMA.     

Dibromo[5,10,15,20‐tetrakis(4‐methoxyphenyl)porphyrinato‐κ4N]platinum(IV) chloroform acetonitrile solvate

In the title compound, [PtBr₂(C₄₈H₃₆N₄O₄)]·0.896CHCl₃·0.569CH₃CN, the centrosymmetric metal complex is octahedral, with the porphyrin ring essentially planar and the Br atoms occupying axial positions. The two independent methoxy­phenyl substituents are tilted at angles of 89.0 and 67.0° with respect to the porphyrin plane. The Pt—N distances are 2.035 (4) and 2.036 (4) Å and the Pt—Br distance is 2.4666 (6) Å. Chloro­form and aceto­nitrile solvent mol­ecules, exhibiting substantial disorder, occupy positions between the porphyrin mol­ecules. This is the first crystal and molecular structure of a Pt^IV–porphyrin complex to be reported.     

Dichlorobis(pyridine‐κN)bis(3,3,3‐trifluoropropyl‐κC1)tin(IV)

In the title compound, [Sn(C₃H₄F₃)₂Cl₂(C₅H₅N)₂], the Sn atom lies on an inversion centre and is octahedrally coordinated by two Cl atoms, two tri­fluoro­propyl groups and two N atoms in an all‐trans configuration. The electronegative tri­fluoro­propyl groups increase the electrophilic properties of the Sn atom, and the Sn—Cl and Sn—N bonds are shortened in comparison with those reported for analogous compounds.     

Ring Opening of 2‐(Benzylamino)‐2H‐1,4‐benzoxazin‐3(4H)‐ones and 2‐Bromo‐2H‐1,4‐benzoxazin‐3(4H)‐ones

Substituted 2‐(benzylamino)‐2H‐1,4‐benzoxazin‐3(4H)‐ones are unstable under alkaline and acidic conditions, undergoing opening of the benzoxazinone ring. 2‐Bromo‐2H‐1,4‐benzoxazin‐3(4H)‐ones show similar degradation under alkaline conditions, while replacement of Br at C(2) to give 2‐hydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐ones was observed only under mild alkaline conditions. Mechanisms of ring opening and degradation to 2‐aminophenol derivatives are proposed.     

Efficient One‐Pot Syntheses of Betti Bases Catalyzed by 1‐Methyl‐3‐(2‐(sulfooxy)ethyl)‐1H‐imidazol‐3‐ium Chloride

The efficient one‐pot syntheses of Betti bases by the three‐component reaction of aromatic aldehyde, 2‐naphthalen, and acetonitrile (or benzamide) catalyzed by 1‐methyl‐3‐(2‐(sulfooxy)ethyl)‐1H‐imidazol‐3‐ium chloride is reported. The solvent can be recycled easily.