119Sn NMR Spectroscopy Research Articles

Intramolecularly coordinated heteroleptic organostannylene tungsten pentacarbonyl complexes 4-tBu-2,6-[P(O)(OiPr)2]2C6H2Sn(X)W(CO)5 (X = Cl, F, PPh2, PPh2[W(CO)5]). Syntheses and reactivity

The synthesis of the intramolecularly coordinated heteroleptic organostannylene tungsten pentacarbonyl complexes 4-tBu-2,6-[P(O)(OiPr)(2)](2)C(6)H(2)Sn(X)W(CO)(5) (1, X = Cl; 2, X = F; 3, X = PPh(2)) and of 4-tBu-2,6-[P(O)(OiPr)(2)](2)C(6)H(2)Sn[W(CO)(5)]PPh(2)[W(CO)(5)], 4, are reported. UV-irradiation of compound 4 in tetrahydrofurane serendipitously gave the bis(organostannylene) tungsten tetracarbonyl complex cyclo-O(2)W[OSn(R)](2)W(CO)(4) (R = 4-tBu-2,6-[P(O)(OiPr)(2)](2)C(6)H(2)), 5, that contains an unprecedented W(0)-Sn-O-W(vi) bond sequence. The compounds 1-5 were characterized by means of single crystal X-ray diffraction analysis, (1)H, (13)C, (19)F, (31)P, (119)Sn NMR, and IR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and elemental analysis. Compound 4 features a hindered rotation about the Sn-P bond.

Synthesis and spectroscopic studies of some new organometallic chelates derived from bidentate ligands

A series of organosilicon(IV) and organotin(IV) complexes having the formulae R_2MCl(L^1), R_2MCl(L^2), R_2MCl(L^3), R_2MCl(L^4), R_2M(L^1)_2, R_2M(L^2)_2, R_2M(L^3)_2, and R_2M(L^4)_2, where M = Si and Sn, and R = CH_3, were synthesized with Schiff bases 5-mercapto-4-(pyridine-2-carboxalideneamino)-s-triazole (HL^1), 4-(furfuralideneamino)-5mercapto-s-triazole (HL^2), 4-(2-chlorobenzylideneamino)-5-mercapto-s-triazole (HL^3), and 4-(4-flourobenzylideneamino)-5-mercapto-s-triazole (HL^4). These complexes were characterized by elemental analysis, molar conductance, and spectroscopic studies, including UV, IR, ^1H, ^{13}C, ^{29}Si, and ^{119}Sn NMR spectroscopy. On the basis of these studies, the resulting complexes are proposed to have trigonal bipyramidal and octahedral geometries.

Trilacunary A-β-Keggin tungstogermanates and -silicates functionalized with phenyltin(iv) electrophiles

The first organic derivative of a beta-Keggin tungstogermanate, the monomeric Keggin anion [{(C(6)H(5))Sn(OH)}(3)(A-beta-GeW(9)O(34))](4-) (1), was the only species isolated from the reaction of (C(6)H(5))SnCl(3) with Na(10)[A-beta-GeW(9)O(34)] in water, whereas the Si-analogue [{(C(6)H(5))Sn(OH)}(3)(A-beta-SiW(9)O(34))](4-) (2) and two dimeric tungstosilicates, the unprecedented species [{(C(6)H(5))Sn(A-beta-H(3)SiW(9)Sn(2)O(37))}(2)O(2)](8-) (3) and the known sandwich-type polyanion [{(C(6)H(5))Sn(OH)}(3)(A-beta-H(3)SiW(9)O(34))(2)](8-) (4), were isolated starting from [A-beta-SiW(9)O(34)](10-). The novel polyanion 3 can be described as the product of a double Sn-C hydrolysis followed by condensation of two subunits of 2 through double Sn-O-Sn bridge formation. Solid-state characterization has been carried out by infrared spectroscopy, thermogravimetry and single-crystal X-ray diffraction, representing the first structural analysis for 4. A full solution multinuclear NMR ((1)H, (13)C, (117)Sn, and (183)W) and solid-state (117)Sn CP-MAS NMR study enabled full characterization of 1. A weak 1-dimensional polyanion association through (Sn)O-HO(t) hydrogen contacts involving one of the protonated bridging O atoms of the (C(6)H(5))(3)Sn(3)O(12) corner-shared triad is observed for 1 by X-ray diffraction, resulting in a local C(s) pseudosymmetry for the Sn centers detected by solid-state (117)Sn NMR spectroscopy.

Diorganotin(IV) compounds containing 2-(Et2NCH2)C6H4 moieties: Configurational stability in solution and solid state structures

Hypercoordinated diorganotin(IV) dichloride, [2-(Et 2 NCH 2 )C 6 H 4 ] 2 SnCl 2 ( 1 ), was prepared by reacting [2-(Et 2 NCH 2 )C 6 H 4 ]Li with SnCl 4 . Halide-exchange reactions between 1 and the appropriate potassium halides gave [2-(Et 2 NCH 2 )C 6 H 4 ] 2 SnX 2 [X = F ( 2 ), Br ( 3 ), I ( 4 )]. Reaction of 1 with excess of Na 2 S gave the cyclo -[{2-(Et 2 NCH 2 )C 6 H 4 } 2 SnS] 2 ( 5 ). The solution behavior of the title compounds in solution was investigated by multinuclear ( 1 H, 13 C, 19 F and 119 Sn) NMR spectroscopy, including variable temperature studies. Single-crystal X-ray diffraction analysis revealed for all compounds intramolecular N → Sn coordination thus resulting in distorted octahedral ( C , N ) 2 SnX 2 configurations. Planar chirality is observed as result of the non-planarity of the SnC 3 N rings; all compounds, however, crystallizing as racemates. The isomers are linked by extensive hydrogen bonds to give different supramolecular architectures in the crystals of compounds 1 , 3 and 4 .

Amino acetate functionalized Schiff base organotin(IV) complexes as anticancer drugs: synthesis, structural characterization, and in vitro cytotoxicity studies

Potassium 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}-4-methyl-pentanoate (L(1)HK) and potassium 2-{[(E)-1-(2-hydroxyphenyl)alkylidene]amino}-4-methyl-pentanoates (L(2)HK-L(3)HK) underwent reactions with Ph(n)SnCl(4-n) (n = 2 and 3) to give the amino acetate functionalized Schiff base organotin(IV) complexes [Ph(3)SnLH](n)(1-3) and [Ph(2)SnL] (4), respectively. These complexes have been characterized by (1)H, (13)C, (119)Sn NMR, IR spectroscopic techniques in combination with elemental analyses. The crystal structures of 1 and 3 were determined. The crystal structures reveal that the complexes exist as polymeric chains in which the L-bridged Sn-atoms adopt a trans-R(3)SnO(2) trigonal bipyramidal configuration with the Ph groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen atom from one carboxylate ligand and the alcoholic or phenolic oxygen atom of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic/phenolic proton moved to the nearby nitrogen atom. The solution structures were predicted by (119)Sn NMR spectroscopy. When these organotin(IV) complexes were tested against A498, EVSA-T, H226, IGROV, M19 MEL, MCF7 and WIDR human tumor cell lines, the average ID(50) values obtained were 55, 80 and 35 ng/ml for triphenyltin(IV) compounds 1-3, respectively. The most cytotoxic triphenyltin(IV) compound in the present report (3) with an average ID(50) value of around 35 ng/ml is found to be more cytotoxic for all the cell lines studied than doxorubicin, cisplatin, 5-fluorouracil and etoposide.

24- and 26-Membered Macrocyclic Diorganotin(IV) Bis-Dithiocarbamate Complexes withN,N′-Disubstituted 1,3- and 1,4-Bis(aminomethyl)benzene and 1,1′-Bis(aminomethyl)ferrocene as Spacer Groups

The potassium bis-dithiocarbamate (bis-dtc) salts of 1,3-bis(benzylaminomethyl)benzene (1,3-Bn-ambdtc), 1,3-bis(iso-butylaminomethyl)benzene (1,3-(i)Bu-ambdtc), 1,4-bis(benzylaminomethyl)benzene (1,4-Bn-ambdtc), and 1,4-bis(iso-butylaminomethyl)benzene (1,4-(i)Bu-ambdtc) were reacted with three different diorganotin dichlorides (R2SnCl2 with R = Me, (n)Bu, and Ph) in 1:1 stoichiometric ratios to give the corresponding diorganotin bis-dithiocarbamates. Additionally, the dimethyltin bis-dithiocarbamate of 1,1'-bis(benzylaminomethyl)ferrocene (1,1'-Bn-amfdtc) was prepared. The resulting complexes have been characterized as far as possible by elemental analysis, FAB(+) mass spectrometry, IR and NMR ((1)H, (13)C, and (119)Sn) spectroscopy, and single-crystal X-ray diffraction, showing that the tin complexes are dinuclear 24- and 26-membered macrocyclic species of composition [{R2Sn(bis-dtc)}2]. As shown by (119)Sn NMR spectroscopy, the tin centers are hexa-coordinated in all cases; however, two different coordination environments are possible, as detected by single-crystal X-ray diffraction. In the dimethyltin derivatives of 1,3-Bn-ambdtc, 1,3-(i)Bu-ambdtc, 1,4-Bn-ambdtc, and 1,1'-Bn-amfdtc and the di-n-butyltin derivative of 1,3-(i)Bu-ambdtc, the metal atoms are embedded in skewed-trapezoidal-bipyramidal coordination polyhedra with asymmetrically coordinating trans-oriented dtc groups. In contrast, in the diphenyltin derivative 1,3-(i)Bu-ambdtc, the metal centers have distorted octahedral coordination with symmetrically coordinating cis-oriented dtc functions. Thus, for the complexes derived from 1,3-Bn/(i)Bu-ambdtc, two different macrocyclic structures were observed. In the dimethyl- and di-n-butyltin derivatives, the bridging bis-dtc ligands adopt U-shaped conformations, while in the case of the diphenyltin derivative, the conformation is L-shaped. Furthermore, two different macrocyclic ring conformations can occur, which differ in the spatial orientation of the substituents attached to the nitrogen atoms (Bn or (i)Bu). The dimethyltin derivatives of 1,4-Bn-ambdtc and 1,1'-Bn-amfdtc have cavities, in which aromatic rings are accommodated in the solid state.

Synthesis and Spectroscopic Investigations of New Schiff Base Complexes of Tin(IV)

The organotin(IV) chlorides SnR 2 Cl 2 (R = Bu and Me) react with a new Schiff base (Hcdpen), obtained from the condensation of methyl-2-[N-(2′-aminoethane)]-amino-1-cyclopentenedithiocarboxylate and pyridine 2-carbaldehyde. The novel adducts [SnMe 2 Cl 2 (Hcdpen)] ( 1 ) and [SnBu 2 Cl 2 (Hcdpen)] ( 2 ) were characterized by elemental analysis, as well as by IR, 1 H NMR, and 119 Sn NMR spectroscopy. Spectroscopic studies show that, in the two new complexes Hcdpen acts as a monodentate neutral ligand and coordinates to the metal only via the pyridine nitrogen atom, while the imine nitrogen atom is not involved in the coordination to the tin. The 119 Sn NMR data are consistent with the presence of five-coordinated tin(IV) in solution.

Synthesis and characterization of the unstable primary amido tin(ii) dimer Sn2{N(H)Dipp}4 (Dipp = C6H3-2,6-Pri2) and the first sesqui-amido hemi-chloride derivative Sn2{N(H)Dipp}3Cl: facile conversion of a primary amide to the imide (SnNDipp)4

The primary tin(ii) amido derivatives Sn(2){N(H)Dipp}(4) () and Sn(2){N(H)Dipp}(3)Cl () (Dipp = C(6)H(3)-2,6-Pr(i)(2)) have been prepared and characterized. Compound was obtained by the transamination of Sn{N(SiMe(3))(2)}(2) with H(2)NDipp in a 1 : 2 ratio or by the reaction of two equivalents of LiN(H)Dipp with SnCl(2). The attempted preparation of Sn(Cl){N(H)Dipp} by reaction of LiN(H)Dipp with SnCl(2) in a 1 : 1 ratio led to the isolation of the unique species Sn(2){N(H)Dipp}(3)Cl, which is the first example of a sesqui-amido derivative of a group 14 element. Both and were characterized by (1)H and (119)Sn NMR spectroscopy, X-ray crystallography and Mössbauer spectroscopy. The structures of and feature two tin centers bridged by -N(H)Dipp ligands with the terminal positions being occupied by two N(H)Dipp () or -N(H)Dipp and -Cl () groups. The compound was found to be unstable under ambient conditions and spontaneously converts to the imide tetramer (SnNDipp)(4) in solution over several days at room temperature, representing a new synthetic route to group 14 element imides.

Solubilizing Sodium Fluoride in Acetonitrile: Synthesis, Molecular Structure, and Complexation Behavior of Bis(organostannyl)methyl-Substituted Crown Ethers

The synthesis of the crown-ether-substituted bis(organostannyl)methanes Ph(3)SnCH(2)Sn(Ph(2))-CH(2)-[16]crown-5 (1) and Ph(2)ISnCH(2)Sn(I)(Ph)-CH(2)-[16]crown-5 (2) is reported. Both compounds have been characterized by elemental analyses, (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopy, and in the case of compound 2 also by electrospray ionization mass spectrometry. Single-crystal X-ray diffraction analysis revealed for the aqua complex 2.H(2)O trigonal-bipyramidal-configured tin atoms with intramolecular Sn(1)-O(1) and Sn(2)-O(1W) distances of 2.555(2) and 2.440(3) A, respectively. The water molecule is trapped in a sandwich-like fashion between the crown ether oxygen atoms O(2) and O(4) and the Sn(2) atom. NMR spectroscopy unambiguously proved the ability of compound 2 in acetonitrile to overcome the high lattice energy of sodium fluoride and to complex the latter under charge separation.

Synthesis and Characterization of New Diorganotin(IV) Complexes with Dithiocarbamate Derivative of Glycine

The novel organotin(IV) complexes, Ba[SnMe 2 (dtc-gly) 2 ] · 2 CH 3 OH (1) and [Sn 3 Bu 6 Cl 2 (dtc-gly) 2 ] (2), have been synthesized by reaction of SnR 2 Cl 2 (R = Me or Bu) with the dithiocarbamate derivative of glycine (dtc-gly). The new complexes have been characterized by elemental analysis, IR, 1H NMR and 119 Sn NMR spectroscopy. Spectroscopic studies show that 1 contains a complex anion with dtc-gly acting as a unidentate ligand coordinated through the dithiocarbamate group. On the basis of 119Sn NMR data, the coordination number of the tin atom in solution is four. Complex 2 has a trimeric structure in which two dtc-gly ligands are coordinated through both the carboxylate and the dithiocarbamate groups between three tin atoms.

Tin(IV) Derivatives of the Tetradentate Ligand N,N'-Bis-(2-Pyridylmethylene) -Ethane-1,2,-Diamine

A series of organotin(IV) (SnClJMu-x, χ = 1, 2, 3) and SnCL, derivatives of N, N'-bis-(2pyridylmethylene)-ethane-1, 2-diamine (pmed) have been prepared in 2:1 (M:L) molar ratio in dichloromethane. The SnClPh3 derivative has afforded an equimolar product in contrast to the other metal precursors. The materials were characterised by infrared, multinuclear ('H, C, Sn) NMR spectroscopy, thermal analysis (TG, DSC), gel permeation chromatography (GPC) and microanalysis. The spectroscopic methods have given evidence for metal-ligand bond formation through pyridyl and azomethine nitrogen atoms. For the SnClPh3 derivative a five-fold coordination metal centre has been revealed by Sn NMR in CH2Cl2.in contrast to the SnClxPh4.x(x = 2, 3, 4) derivatives. In those both sixand seven-fold coordination species have been revealed in DMF. The Sn NMR resulting data suggest that a dynamic process has taken place in solution, leading to a structural rearrangement by auto-association. In addition, the GPC technique has revealed in DMF higher values of weight-average molar mass in comparison to that established by the elemental analysis. However, the molar mass obtained for those compounds does not correspond to polymeric materials, as confirmed by DSC analysis.

Synthesis and Characterization of Diphenyltin(IV) Dicarboxylates Containing Germanium

Twelve new germanium substituted diphenyltin dipropionates with the general formula (R 1 GeCHR 2 -CHR 3 COO) 2 SnPh 2 where R 1 = N(CH 2 CH 2 O) 3 , (C 6 H 5 ) 3 and (CH 3 C 6 H 4 ) 3 , R 2 = H, CH 3 , C 6 H 5 , p-CH 3 C 6 H 4 , p-CH 3 OC 6 H 4 , p-ClC 6 H 4 , and R 3 = H, CH 3 have been synthesized by the reaction of diphenyltin oxide with a germanium substituted propionic acid. All the compounds were characterized by elemental analysis, IR, multi-nuclear ( 1 H, 1 3 C, 1 1 9 Sn) NMR and Mossbauer spectroscopies as well as mass spectrometry. The in vitro antibacterial activity of selected compounds is also reported.

Rationally functionalized deltahedral zintl ions: synthesis and characterization of [Ge9-ER3]3-, [R3E-Ge9-ER3]2-, and [R3E-Ge9-Ge9-ER3]4- (E=Ge, Sn; R=Me, Ph).

Six new derivatized deltahedral Zintl ions have been synthesized by reactions between the known Zintl ions Ge(9) (n-) with the halides R(3)EX and/or the corresponding anions R(3)E(-) for E=Ge or Sn. This rational approach is based on our previous discovery that these derivatization reactions are based on nucleophilic addition to the clusters. All species were structurally characterized as their salts with potassium countercations sequestered in 2,2,2-crypt or [18]crown-6 ether. The tin-containing anions were characterized also in solutions by (119)Sn NMR spectroscopy. The reaction types for such substitutions and the structures of the new anions are discussed.

Reactions of Phenyllithium with the Stannylene Ar*SnPh (Ar* = C6H3-2,6-Trip2; Trip = C6H2-2,4,6-Pri3) and the Synthesis of the Distannylstannylene Sn(SnPh2Ar*)2: Contrasting Behavior in Methyl and Phenyl Derivatives

The reaction of LiPh with Ar*SnPh (Ar* = C 6 H 3 -2,6-Trip 2 ; Trip = C 6 H 2 -2,4,6-Pr i 3) afforded either the monomeric etherate (Et 2 O)LiSnPh 2 Ar* (1) or the dimer (LiSnPh 2 Ar*) 2 (2). The reaction of 2 with SnCl 2 in a 1:1ratio in Et 2 O yielded the monomeric distannylstannylene Sn(SnPh 2 Ar*) 2 (3). The compounds 1-3 were characterized by 1 H, 7 Li, 1 3 C, and 1 1 9 Sn NMR and UV-vis spectroscopy. Complete single-crystal X-ray crystal structures of 2 and 3 were determined as well as a partial structure for 1. The structure of 1 showed that the tin was pyramidally coordinated by the three organic groups as well as by lithium. The lithium was found to be ligated by ether and η 6 -coordinated by one of the phenyl rings. The structure of 2 showed that it was dimerized through η 6 -interactions of a tin-coordinated lithium with a phenyl group of a partner monomer rather than through tin-tin bonding. The structure of 3 featured a central, two-coordinate tin(II) bound to two SnPh 2 Ar* groups with long Sn-Sn distances near 2.96 A and a very wide Sn-Sn-Sn angle of 115.19(2)°. The 1 1 9 Sn NMR chemical shift of the central tin is 3752 ppm, which is the furthest downfield 1 1 9 Sn NMR chemical shift recorded for a stannylene.

One-step preparation, structural assignment, and X-ray study of 2,2-di-n-butyl- and 2,2-diphenyl-6-aza-1,3-dioxa-2-stannabenzocyclononen-4-ones derived from amino acids.

Twenty-four 2,2-di-n-butyl- and 2,2-diphenyl-6-aza-1,3-dioxa-2-stannabenzocyclononen-4-ones, each having a transannular N-->Sn bond, have been prepared by one-step reactions of alpha-amino acids (1 a-l), salicylaldehyde (2), and either di-n-butyltin(IV) oxide (3) or diphenyltin(IV) oxide (4). The new methodology constitutes an easy, highly efficient one-step synthesis of diorganotin(IV) derivatives, such as 5 a-l and 6 a-l, from iminic tridentate ligands without isolation of the Schiff bases. The structures of all the compounds have been established by a combination of (1)H, (13)C, (15)N, and (119)Sn NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis. In all cases, the (119)Sn chemical shifts, as well as the (1)J((119)Sn,(13)C) coupling constants, are indicative of pentacoordinated tin atoms in solution. The structures of compounds 5 a, d, f, 6 a, b, b-racemic, c, d, f, g, and l have been established by single-crystal X-ray diffraction analyses. The tin atoms in 5 d, f, 6 a, b, b-racemic, c, d, g, and l each have a distorted trigonal-bipyramidal (TBP) geometry, with the oxygen atoms from the phenol and carboxylate moieties occupying the axial positions, and the imine nitrogen and phenyl or n-butyl substituents occupying the equatorial positions. Compounds 5 a and 6 f show distorted octahedral (DOC) geometries due to intermolecular coordination of the carbonyl oxygen to the tin atom, in a trans disposition to the N-->Sn bond, leading to trimeric 5 a and a polymeric structure for compound 6 f. Additionally, measurement of the one-bond coupling constants (1)J((119)Sn,(13)C) in diphenyltin(IV) complexes (6 a-l) and their correlation with the CSn-C bond angles has allowed the derivation of an equation that can be applied to assess the geometry around the tin atom for other diphenyltin(IV) compounds in solution.

Self-assembly of dialkyltin(IV) moieties and aromatic dicarboxylates to complexes with a polymeric or a discrete trinuclear macrocyclic structure in the solid state and a mixture of fast interchanging cyclooligomeric structures in solution.

It is well-known that the structures of trialkyltin(IV) carboxylates can be either monomeric, polymeric, or cyclooligomeric in the solid state. In contrast, all dialkyltin(IV) dicarboxylates characterized so far in the solid state have monomeric or polymeric structures, however, for some cases it has been proposed that their solution-state structure is cyclooligomeric. In order to generate more information on this subject, dimethyl- and di-n-butyltin(IV) complexes with phthalic and isophthalic acid have been prepared and analyzed both in solution and in the solid state. The solid-state structures of the two dialkyltin(IV) phthalates examined herein contain polymeric molecular chains, however, with supramolecular Sn.O' interactions, which result in the generation of cyclooligomeric units. This provides evidence for the presence of discrete cyclooligomeric structures in solution, which are involved in fast dynamic exchange equilibria as evidenced by (1)H, (13)C, and (119)Sn NMR spectroscopy. In the case of the two dialkyltin(IV) isophthalate complexes studied herein (R = Me, n-Bu), only the di-n-butyltin derivative is soluble and NMR spectroscopy as well as FAB(+) spectrometry indicates the formation of cyclic dinuclear, trinuclear, and/or tetranuclear species in solution, which may be involved also in fast dynamic exchange equilibria. In the solid state, however, discrete cyclotrinuclear units can be identified, in which the 24-membered macrocyclic cavity is almost completely planar, having six oxygen atoms directed into its interior and six Sn-n-butyl groups approximately perpendicular to the molecular plane. The diameter of the cyclic cavity can be described by the transannular O.O distances that vary from 7.68 to 7.84 A, being large enough for the introduction of linear alkyl groups. This can be demonstrated by the supramolecular structure of this compound, which contains a new type of bis[2]pseudorotaxane formed between two molecules through mutual threading via two of the Sn-butyl groups. Such a supramolecular entity has been unknown so far, since the usual composition of bis[2]pseudorotaxanes is the trimolecular combination of a macrocyclic ring system with two threads.

Structural and Mechanistic Studies of Halogenation of a Tin(II) N-Functionalized Alkyl

The halogenation of the tin(II) alkyl SnR 1 2 (1) [R 1 = CH(SiMe 3 )C 9 H 6 N-8] to give R 1 2 SnX 2 [X = F (2), Cl (3), Br (4), I (5)] was investigated by reacting 1 with SnX 2 (X = F, Cl, Br, and I), PbCl 2 , BCl3, and X 2 (X = Br, I), respectively. 1 H, 1 1 9 Sn NMR and X-ray analysis showed that the reactions with SnX 2 under a milder experimental condition afforded intermediate compounds, R 1 2 Sn→SnX 2 [X = Cl (6), Br (7)] and R 1 SnX [X = Cl (8), Br (9)]. Further heating gave the final products R 2 SnX 2 . The X-ray structures of 2-6 and 9 have been determined. The dynamic exchange process between diastereoisomers of R 1 SnX (X = Cl, Br) has been studied by variable-temperature 1 H and 1 1 9 Sn NMR spectroscopy.

A Novel Configuration of a Benzoylacetonato-Diorganotin Species is Modified by an Electron-Withdrawing Substituent on Tin − Synthesis, IR and NMR Spectroscopy, Structure, and ab initio Studies

Diorganotin(IV) complexes of the β-diketonato benzoylacetonato ligand were synthesized and characterized with IR and multinuclear (H, C, Sn) NMR spectroscopy. The X-ray diffraction study of bis(benzoylacetonato)di-tert-butyltin(IV) shows two independent molecules in the crystallographic unit cell. The metal polyhedron is a distorted octahedral (Skewed Trapezoidal Bipyramidal) with the trans angle C−Sn−C of 151.5(5)°. Each ligand chelates the metal with different donor abilities [Sn−O bond lengths of 2.423(8) A and 2.135(8) A in one ligand, and 2.107(9) A and 2.357(8) A in the other]; results for the 2nd molecule are similar. The coordination arrangement differs from those of related bis(β-diketonato)diorganotin derivatives containing asymmetric ligands, which are characterized by an approximate Cs symmetry, in that both benzoylacetonato ligands point their methyl (and phenyl) substituents across (anti) the metal atom. Chelate planarity and some phenyl-chelate co-planarity was observed. Hartree−Fock (HF) and Density Functional Theory (DFT) calculated structures are in good agreement with those obtained using X ray analysis. DFT and HF calculated structures of bis(benzoylacetonato)diphenyltin(IV), having a similar connectivity as bis(benzoylacetonato)di-tert-butyltin(IV), differ markedly: the phenyls subtend a C−Sn−C bond angle of 180°, all Sn−O bond lengths are equal and the tin coordination sphere is a regular octahedron with the ligand bzac being isobidentate. This arrangement is caused by the phenyl electronic withdrawal effect. However, IR data for this compound show several Sn−O bands inconsistent with this configuration and suggest a different connectivity. Additional DFT structural calculations for (bzac)2SnPh2, performed on the connectivity resembling the “normal” syn geometry, show a conformational energy slightly lower than that of the centrosymmetric arrangement. Low temperature NMR spectra illustrate the possible rearrangements in solution. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Syntheses, crystal structures, and density functional theory calculations of the closo-[1-M(CO)(3)(eta(4)-E(9))](4-) (E = Sn, Pb; M = Mo, W) cluster anions and solution NMR spectroscopic characterization of [1-M(CO)(3)(eta(4)-Sn(9))](4-) (M = Cr, Mo, W).

The closo-[1-M(CO)(3)(eta(4)-E(9))](4-) (E = Sn, Pb; M = Mo, W) anions have been obtained by extracting the binary alloys KSn(2.05) and KPb(2.26) in ethylenediamine (en) in the presence of 2,2,2-crypt or in liquid NH(3) followed by reaction with M(CO)(3).mes (M = Mo, W) or Cr(CO)(3).tol in en or liquid NH(3) solution. Crystallization of the molybdenum and tungsten salts was induced by vapor diffusion of tetrahydrofuran into the en solutions. The salts [2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Sn(9))].en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 4, a = 16.187(3) A, b = 25.832(4) A, c = 29.855(5) A, alpha = 111.46(1) degrees, beta = 102.84(2) degrees, gamma = 92.87(2) degrees at -95 degrees C (M = Mo) and a = 17.018(3) A, b = 27.057(5) A, c = 28.298(6) A, alpha = 66.42(3) degrees, beta = 76.72(3) degrees, gamma = 87.27(3) degrees at 20 degrees C (M = W). The salts (CO)(3)M(en)(2)[2,2,2-crypt-K](4)[1-M(CO)(3)(eta(4)-Pb(9))].2.5en (M = Mo, W) crystallize in the triclinic system, space group P1, Z = 2, a = 16.319(3) A, b = 17.078(3) A, c = 24.827(5) A, alpha = 71.82(3) degrees, beta = 83.01(3) degrees, gamma = 81.73(3) degrees at -133 degrees C (M = Mo) and a = 16.283(4) A, b = 17.094(3) A, c = 24.872(6) A, alpha = 71.62(2) degrees, beta = 82.91(2) degrees, gamma = 81.35(2) degrees at -153 degrees C (M = W). The [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions were also characterized in liquid NH(3) solution by (119)Sn, (117)Sn, and (95)Mo NMR spectroscopy. Unlike their fluxional precursor, nido-Sn(9)(4-), NMR studies show that the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are rigid on the NMR time scale. All possible inter- and intraenvironmental couplings, J((119,117)Sn-(119,117)Sn), J((119,117)Sn-(183)W), and one J((119,117)Sn-(95)Mo) coupling, have been observed and assigned. Complete spin-spin coupling constant assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the (119)Sn and (117)Sn NMR spectra and that arise from natural abundance tin isotopomer distributions and from natural abundance (183)W, in the case of [1-W(CO)(3)(eta(4)-Sn(9))](4-). Both the solid state and solution structures of the [1-M(CO)(3)(eta(4)-Sn(9))](4-) anions are based on a closo-bicapped square antiprismatic structure in which the transition metal occupies a cap position. The cluster structures are consistent with Wade's rules for 22 (2n + 2) skeletal electron systems. Electron structure calculations at the density functional theory (DFT) level provide fully optimized geometries that are in agreement with the experimental structures. Complete assignment of the NMR spectra was also aided by GIAO calculations. The calculated vibrational frequencies of the E(9)(4-) and [1-M(CO)(3)(eta(4)-E(9))](4-) anions are also reported and are used to assign the solid-state vibrational spectra of the [1-M(CO)(3)(eta(4)-E(9))](4-) anions.

Ab initio structure determination of a small-pore framework sodium stannosilicate.

The structure of a small-pore framework sodium stannosilicate Na(2)SnSi(3)O(9).2H(2)O (AV-10) has been determined ab initio from powder X-ray diffraction data (XRD). The unit cell is orthorhombic (space group C222(1), Z = 4) with cell dimensions a = 7.9453(5), b = 10.3439(7), c = 11.6252(7) A, V = 955 A(3). The structure of AV-10 is composed of corner sharing SnO(6) octahedra and SiO(4) tetrahedra, forming a three-dimensional framework structure. The SiO(4) tetrahedra form helix chains along [001] interconnected by SnO(6) octahedra. The SnO(6) octahedra are isolated by SiO(4) tetrahedra and, thus, there are no Sn-O-Sn linkages. AV-10 has been characterized by chemical analysis, powder XRD, scanning electron microscopy, (29)Si, (119)Sn, single- and (FAM) triple-quantum (23)Na MAS NMR spectroscopy, thermogravimetry (TGA), and nitrogen adsorption isotherms. The zeolitic water of AV-10 is reversibly lost. The dehydrated material has been studied in situ by powder XRD, TGA, and, in particular, triple-quantum (23)Na MAS NMR.