Three‐centre Rh?H?Sn bonds: an NMR study of the effects of varying the electron density on rhodium

The complexes [Rh(X)(H)(SnPh₃)(PPh₃)(L)] (X = NCBPh₃ (a), N(CN)₂ (b), NCS (c), NCO (d), N₃ (e); L = 1‐methylimidazole) ( 1 ) show systematic changes in δ(¹¹⁹Sn), δ(¹⁰³Rh), J(¹¹⁹Sn–¹H) and J(¹¹⁹Sn–¹⁰³Rh) that are related to the electron‐donating properties of X. As X becomes more electron‐rich, δ(¹⁰³Rh), J(¹¹⁹Sn–¹H) and J(¹¹⁹Sn–¹⁰³Rh) increase and δ¹¹⁹Sn) decreases. The related complexes trans‐[Rh(X)(H)(SnPh₃)(PPh₃)₂(L)] (X = N(CN)₂, NCO; L = 4‐carboxymethylpyridine (x), pyridine (y) and 4‐dimethylaminopyridine (z)) ( 2 ), show a continuation of the trends in δ(¹¹⁹Sn) and J(¹¹⁹Sn–¹H), but not δ(¹⁰³Rh) or J(¹¹⁹Sn–¹⁰³Rh). Data for 1 and 2 show that within certain limits of type of ligand varied (X = N‐donor, L = a pyridine) and coordination geometry, the response of δ(¹¹⁹Sn) and J(¹¹⁹Sn–¹H) to changes in electron density on rhodium is largely independent of the means by which the change is effected.Copyright © 2001 John Wiley & Sons, Ltd.     

A study of trialkyltin β-aryl-β-triphenylgermyl propionates

Twenty new compounds of the form Ph₃GeCHArCH₂COOSnR₃ (R = n-Bu, cyclohexyl; Ar = substituted phenyl) have been synthesized. Their structures were characterized by IR and ¹¹⁹Sn and ¹H NMR spectroscopy. The compounds are five-coordinated carboxylate bridged polymers when R = n– Bu; when R = cyclohexyl (Cy) they are four-coordinate. ¹¹⁹Sn NMR measurements of chemical shift for the two series of compounds have shown that there is a good linear relationship for the chemical shift of ¹¹⁹Sn NMR between the tributyltin and tricyclohexyltin propionates, viz. δ¹¹⁹Sn(Bu₃Sn) = 1.0474 δ ¹¹⁹Sn(Cy₃Sn) + 95.8076, n = 5, r = 0.993. The structure of one compound was determined by X-ray diffraction. It exists as a monomeric four-coordinated species in a distorted tetrahedronal geometry.     

13C- und 199Sn-NMR untersuchungen an alkinylstannanen

Chemical shifts δ(¹³C), δ(¹¹⁹Sn) and coupling constants J(¹¹⁹Sn¹³C) for alkynylstannanes of the type R_4-nSn(CCR′)_n (n = 1–4) are reported. The values of ¹J(¹¹⁹Sn¹³C) and ²J(¹¹⁹SnC¹³C) depend upon the nature of the substituent R′. ¹J(¹¹⁹Sn¹³C) in Sn(CCCH₃)₄ is 1168 Hz, much larger than a value predicted in the literature of ca. 700 Hz. The comparison of δ(¹¹⁹Sn) for (CH₃)₂Sn(CCR′)₂ and 1,1,4,4-tetramethyl-1-stannacyclohexadi-2,5-ene suggests that the δ(¹¹⁹Sn) of alkynylstannanes are determined only to a small extent by the diamagnetic anisotropic effect of the CC-triple bond.     

Synthesis, 119Sn, 13C and 195Pt NMR studies of five-coordinate rhodium(I), iridium(I) and platinum(II) complexes containing three trichlorostannate ligands

The synthesis and ¹¹⁹Sn NMR characteristics of new five-coordinate tris(trichlorostannato) complexes of Rh^I, Ir^I and Pt^II are reported. The Rh^I and Ir^I complexes are complex dianions of the form (PPN)₂[M(SnCl₃)₃L₂] where L can be CO, CN (cyclohexyl) or L₂, a diolefin such as 1,5-COD or NBD (norbornadiene). The anionic platinum complexes (PPN)[Pt(SnCl₃)₃L₂] contain similar L ligands. A number of neutral monotrichlorostannato complexes of type [M(SnCl₃)L₄] including [Ir(SnCl₃)(NBD)(1,5-COD)] have been prepared and characterized. Their δ(¹¹⁹Sn), δ(¹³C), δ(¹⁹⁵Pt) as well as ¹J(¹⁰³Rh, ¹¹⁹Sn), ¹J(¹⁹⁵Pt, ¹¹⁹Sn), ²J(¹¹⁹Sn, ¹¹⁷Sn) and ²J(¹¹⁹Sn, ¹³C) data are given. A trans influence series, based on ¹J(¹⁹⁵Pt, ¹¹⁹Sn), reveals the following sequence: H^? > PR₃ > AsR₃ > SnCl₃^? > olefin > Cl^?.     

Über Polystannane. III. 1,2-Dichlortetramethyldistannan,eine Sn?Sn-verknüpfte helicale Bandstruktur [(…︁SnMe2?Cl…︁SnMe2?Cl…︁)∞]2

On Polystannanes. III. 1,2-Dichloro-tetramethyl-distannane. Forming a Sn? Sn-connected Helical Double Chain Structure [(…?SnMe₂Cl…?SnMe₂? Cl…?)_∞]₂ The crystal structure of the title compound has been determined at ?160°C and refined to R = 0.071 (bond lengths Sn? Sn 277.0(2), Sn? Cl 244.2(3) and 244.8(3), Sn? C 214(2) pm). Intermolecular Sn…?Cl connection (324.0(3) and 329.2(3) pm) results in a double chain structure. ¹¹⁹Sn-NMR spectra in CH₂Cl₂ and acetone exhibit a movable temperature dependent coordination of acetone at the distannane (¹J(¹¹⁹Sn? ¹¹⁹Sn) 8000 to 9000 Hz; appr. 5000 Hz in CH₂Cl₂).     

119Sn Chemical Shifts in five- and six-coordinate organotin chelates

¹¹⁹Sn chemical shifts, δ(¹¹⁹Sn), relative to Me₄Sn in five- and six-coordinate organotin chelates were measured by means of FT NMR spectroscopy. ¹¹⁹Sn resonances were found to lie between ca. ?90 and ?330 ppm in the five-coordinate compounds and between ca. ?125 and ?515 ppm in the six-coordinate derivatives. thus δ(¹¹⁹Sn) moves upfield by 60–150 ppm with a change of the coordination number of tin from four to five and by 130–200 ppm from five to six. the δ(¹¹⁹Sn) values were shifted depending on the nature of chelating ligands and this shift was discussed in terms of the bonding between the ligand and tin. Replacement of methyl groups attached to tin by phenyl groups in five- and six-coordinate compounds induces upfield shifts in δ(¹¹⁹Sn) parallel to those found in four-coordinate organotin halides.     

195Pt, 119Sn and 31P NMR studies of alkyl,aryl and acyl trichlorostannate complexes of platinum(II). The crystal structure of trans-[Pt(SnCl3)(COC6H5)(PEt3)2]

¹⁹⁵Pt, ¹¹⁹Sn and ³¹P NMR characteristics of the complexes trans-[Pt(SnCl₃)(carbon ligand)(PEt₃)₂] (1a-1e) are reported, (carbon ligand = CH₃ (1a), CH₂Ph (1b), COPh (1c), C₆Cl₅ (1d), C₆Cl₄Y (e); Y = meta- and para-NO₂, CF₃, Br, H, CH₃, OCH₃, or Pt(SnCl₃)(PEt₃)₂. The values of ¹J(¹⁹⁵Pt, ¹¹⁹Sn) vary from 2376 to 11895 Hz with the COPh ligand having the smallest and the C₆Cl₅ ligand the largest value, making a total range for this coupling constant, when the dimer syn-trans-[PtCl(SnCl₃)(PEt₃)]₂ is included, of ca. 33000 Hz. In the meta- and para-substituted phenyl complexes ¹J(¹⁹⁵Pt, ¹¹⁹Sn) (a) is greater for electron-withdrawing substituents, (b) varies more for the meta-substituted derivatives (5634 to 7906 Hz) than for the para analogues (6088 to 7644 Hz) and (c) has the lowest values when the Pt(SnCl₃)(PEt₃)₂ group is the meta- or para-substituent. The direction of the change in ¹J(¹⁹⁵Pt, ¹¹⁹Sn) is opposite to that found for ¹J(¹⁹⁵Pt, ¹¹⁹P). For the aryl complexes linear correlations are observed between δ(¹¹⁹Sn), ¹J(¹⁹⁵Pt, ¹¹⁹Sn), ¹J(¹⁹⁵Pt, ³¹P), ¹J(¹¹⁹Sn, ³¹P) and the Hammett substituent constant σⁿ. δ(¹¹⁹Sn) and ¹J(¹⁹⁵Pt, ¹¹⁹Sn) are related linearly to v(Pt-H) in the complexes trans-[PtH(C₆H₄Y)(PEt₃)₂]; δ(¹¹⁹Sn) and δ(¹H) (hydride) are also linearly related. Based on ¹J(¹⁹⁵Pt, ¹¹⁹Sn), the acyl ligand is suggested to have a very large NMR trans influence. The differences in the NMR parameters for (1a-e) are rationalized in terms of differing σ- and π-bonding abilities of the carbon ligands.The structure of 1c has been determined by crystallographic methods. The complex has a slightly distorted square planar geometry with trans-PEt₃ ligands. Relevant bond lengths (Å) and bond angles (°) are: PtSn, 2.634(1), PtP, 2.324(4) and 2.329(4), PtC, 2.05(1); PPtP, 170.7(6), SnPtC, 173.0(3), SnPtP, 92.1(1), 91.7(1), PPtC, 88.8(4) and 88.3(4). The PtSn bond separation is the longest yet observed for square-planar platinum trichlorostannate complexes, and would be consistent with a large crystallographic trans influence of the benzoyl ligand. The PtSn bond separation is shown to correlate with ¹J(¹⁹⁵Pt, ¹¹⁹Sn).     

Mössbauer study of defect119Sn atoms with ligands from silver to iodine

Mössbauer emission spectra of defect¹¹⁹Sn atoms arising from¹¹⁹Sb were measured in InSb, GaSb, CdSb, ZnSb, In₂Te₃, CdTe, and Ag₂Te labeled with¹¹⁹Sb or its parent^119mTe. Together with the results of our previous studies, the isomer shifts of defect and normal¹¹⁹Sn were shown to correlate with the electronegativity of ligands from silver to iodine.     

Über polystannane: II. I(t-Bu2Sn)4I,ein 1,4-difunktionelles tetrastannan

The compound I(t-Bu₂Sn)₄I has been synthesized by controlled cleavage of the related cyclotetrastannane (t-Bu₂Sn)₄ with iodine in toluene. Both compounds have been investigated by mass, NMR and vibrational spectra. I(t-Bu₂Sn)₄I: δ(¹¹⁹Sn_terminal) 67.7, δ(Sn_central) 17.4 ppm; ¹J(SnSn) 2199 (terminal-central) and 1575 (central-central), ²J(SnSn) 20 (terminal-central), ³J (SnSn) 307 Hz (terminal-terminal); ν(SnSn) 119, ν(SnI) 167 cm^?1. (t-Bu₂Sn)₄: δ(Sn) 87.4 ppm; ν(SnSn) 125 cm^?1. The crystal structure of I(t-Bu₂Sn)₄I has been determined (R = 0.071): bond lengths SnSn 289.5(1) (terminal-central) and 292.4(1) (central-central), SnI 275.3(1) pm. The conformation of the chain ISn₄I is all trans.     

Mössbauer studies on ferrocene complexes: XV. Structure and reactivity of trialkyl- and triaryl-stannyl ferrocenes

⁵⁷Fe and ¹¹⁹Sn Mössbauer data are reported for mono- and bis-triorganostannyl ferrocenes together with ¹¹⁹Sn NMR chemical shifts. The reactions of bis-triphenyl-stannylferrocene Fc(SnPh₃)₂ with various electrophiles have been studied. Acid cleavage occurred with both FcSn and PhSn bond fission. In contrast, mercuri-destannylation with HgCl₂ gave only Fc(HgCl)₂. Iodination gave a mixture of the mono- and bis-iodides Fc(SnPh₃)(SnPh₂I)₂ and Fc(SnPh₂I)₂ resulting from dominant PhSn cleavage. Oxidation of Fc(SnPh₃)₂ by FeCl₃ required more than one equivalent of oxidant. The ⁵⁷Fe and ¹¹⁹Sn Mössbauer spectra of the resultant ferrocinium ion was notable for the appearance of a measurable quadrupole splitting in both cases; this is discussed in terms of polar and steric effects.     

Synthesis and spectroscopic studies on organotin derivatives of biologically active Schiff bases

Some five- and six-coordinated di- and tri-n-butyl tin(IV) complexes of the type Bu₂SnL, Bu₂SnL₂ and Bu₃SnL (where L is the anion of a monofunctional bidentate or bifunctional tridentate Schiff base) have been synthesized and characterised on the basis of microanalyses, molecular weight determinations, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ¹¹⁹Sn Mössbauer spectroscopy. These complexes are highly active towards bacteria.     

The preparation and 119Sn and 19F NMR spectra of some trifluoromethylphenyltin(IV) compounds

The preparation of a series of new trifluoromethylphenyltin(IV) compounds, Bu_nSn(C₆H₄CF₃-3)_4-n, (C₆H₄CF₃-3)SnCl₃, (C₆H₄CF₃-2)SnCl₃, and some related adducts with 2,2¹-bipyridyl and 1,10-phenanthroline, is described. ¹¹⁹Sn and ¹⁹F chemical shifts have been determined, together with values of J(¹¹⁹Sn=F) and ³J(¹¹⁹Sn=H_itortho), and the possibility of a “through space” tinfluorine coupling mechanism is also discussed.     

Über gemischte bindungen in der IV. hauptgruppe: III. Octaphenylpropan-analoga Ph3SnSiPh2SnPh3 und Ph3SnGePh2SnPh3, korrelation zwischen geminalen NMR-kopplungen 2J(SnMSn) und nicht-bindenden Sn⋯Sn-abständen

Reaction of Ph₃SnLi with Ph₂SiCl₂ or Ph₂GeCl₂ at −78°C in THF yields (Ph₃Sn)₂SiPh₂ (1) and (Ph₃Sn)₂GePh₂ (2). The crystal structure of 1 (R = 0.075) exhibits SnSi distances of 257.2(4) and 257.9(5) pm, an SnSiSn angle of 118.5(2)°, and a central C₃SnSiC₂SnC₃ molecular skeleton with symmetry close to C₂. The geminal NMR coupling ²J(¹¹⁹Sn ⋯ ¹¹⁹Sn) in 1, and in a tri-, tetra- and pentastannane series shows a linear correlation to their respective non-bonded d(Sn ⋯ Sn) distances (I(t-Bu₂Sn)₄I: 20 Hz/496 pm; 1: 724 Hz/443 pm).     

On the occurrence of 119Sn-CIDNP during some reactions of trimethylstannyl radicals

The ¹¹⁹Sn nuclei of hexamethylditin, formed during the photochemical reaction of trimethyltin hydride with d₁-t-butyl peroxide or dibenzyl ketone, or during the thermal decomposition of azodusobutyronitrile with trimethyltin hydride, exhibit CIDNP. The nuclear polarisation is built up in radical pairs $\text{Me}{}_3\text{Sn··SnMe}{}_3$¹. The full CKO theory has to be used for explaining the net effect in the main ¹¹⁹Sn signals of the hexamethylditin. The high field approximation is not valid because of the high value of the ¹¹⁹Sn hyperfine splitting in trimethylstannyl radicals. The multiplet effect in the ¹¹⁷Sn satellites is interpreted in terms of the high field treatment. A negative sign is found for a_117Sn(Me₃Sn) and a_119Sn(Me₃Sn). ¹¹⁹Sn-CIDNP also appears in benzyltrimethyltin during photolysis of dibenzylketone with trumethyltin hydride. It is concluded from ¹H-CIDNP investigations that nuclear polarisations built up in radical pairs containing both stannyl radicals and others are not observed in hexamethylditin. A positive sign is found for

.     

Structures and relationship between the 119SnNMR chemical shifts and pKa of their parent acids in organotin (I∇) carboxylates

Ten di-n-butyltin(I∇) carboxylates [(ⁿBu₂Sn-OCOR′)₂O]₂ and ⁿBu₂Sn(OCOR′)₂ (R′ = CCl₃, CHCl₂, CH₂Cl, PhCH = CH, and 2,2,3,3-tetramethylcyclopropyl) were synthesized and characterized by IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopy and elemental analysis. Together with other series of organotin(I∇) carboxylates, their structural features were discussed. The relationship between the ¹¹⁹Sn NMR chemical shifts in the organotin(I∇) carboxylates [(ⁿBu₂SnOCOR′)₂O]₂, ⁿBu₂Sn(OCOR′)₂, ⁿBu₃SnOCOR′, Ph₃SnOCOR′ and the pK_a values of their parent acids R′COOH was studied. The results have shown that the log[-δ(¹¹⁹Sn)] of the same series of carboxylates is linearly related to the pK_a of R′COOH. It seems that the better is the linearity between the log[−δ(¹¹⁹Sn)] and the pK_a, the more analogous are the structures of the same series of carboxylates. © 1996 John Wiley & Sons, Inc.     

Substituent chemical shifts of the organotin moiety in compounds of the type RSnMenCl3 − n (n = 0 to 3; R = n-alkyl)

The ¹³C and ¹¹⁹Sn NMR spectra of 33 organotin compounds of the type RSnMe_nCl_{3 ? n} and related types are discussed. The substituent effects of the groups SnMe₃, SnMe₂Cl, SnMeCl₂ and SnCl₃ (and of some related groups) on the carbon chemical shifts in the alkyl group R have been determined; the SnMe₃ group causes a small upfield shift of the carbon attached to it, while the other groups cause downfield shifts. The shifts show a monotonic change on replacing methyl groups in Me₃Sn by chlorine atoms. The effects on carbons further removed from the tin atom are discussed. Variation in R causes little change in ⁿJ(Sn? C) or δ(¹¹⁹Sn).     

New pentacoordinated Schiff-base diorganotin(IV) complexes derived from nonpolar side chain α-amino acids

In this work we report the synthesis and spectroscopic characterization of twenty new pentacoordinated diorganotin(IV) compounds. These compounds have been prepared in good yields by multicomponent reactions (MCRs) of α-amino acids (isoleucine, leucine, methionine, phenylalanine and aminophenylacetic acid), 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde and either di-n-butyltin(IV) oxide or diphenyltin(IV) oxide. All compounds were characterized by IR spectroscopy, ¹H, ¹¹⁹Sn and ¹³C NMR spectroscopy and mass spectrometry. Each compound has a coordinative N→Sn bond and shows the expected ¹¹⁹Sn NMR chemical shift indicative of a pentacoordinated or hexacoordinated tin atom in CDCl₃ and DMSO-d₆, respectively. These compounds were also tested in tumoral cell lines, HeLa, HCT-15 and MCF-7, in order to evaluate the antiproliferative activity and to obtain the medial inhibitory concentrations (IC₅₀) values.     

Structural features of some organotin(IV) complexes of semi- and thio-semicarbazones

Some five- and six-coordinated di and tri-n-butyl tin(IV) semi- and thio-semi carbazates have been synthesized. The characterization of these complexes, by IR, NMR (¹H, ¹³C, ¹¹⁹Sn), ¹¹⁹Sn), ¹¹⁹Sn Mössbauer and Mass spectroscopies along with X-ray diffraction, reveals that complexes of biionic ligands of the type Bu₂Sn L″ are five-coordinated having trigonal bipyramidal geometry. However, complexes of monoionic ligands of the type Bu₂SnL′₂ are six-coordinated in a distorted cis-octahedral geometry and Bu₃SnL′ are five-coordinated with a trigonal bipyramidal structure. X-ray structural studies on the compound Bu₂Sn(O.C₆H₄.CH:N.N.CS.NH₂), show that it crystallizes in a monoclinic lattice with a = 16.90 Å, b = 9.71 Å, c = 8.60 Å, and β = 103°45′.     

1,1‐Organoboration of bis(trimethylstannyl)ethyne with trimethylsilyl‐ and dimethylsilyl‐dialkylboryl‐substituted alkenes: organometallic‐substituted allenes

The reactions of bis(trimethylstannyl)ethyne, Me₃Sn–C?C–SnMe₃ ( 4 ), with trimethylsilyl‐ or dimethylsilyl‐dialkylboryl‐substituted alkenes 1 – 3 afford organometallic‐substituted allenes 5 , 6 and 8 , 9 in high yield. In the case of (E)‐2‐trimethylsilyl‐3‐diethylboryl‐2‐pentene ( 1) , a butadiene derivative 7 could be detected as an intermediate prior to rearrangement into the allene. All reactions were monitored by ²⁹Si and ¹¹⁹Sn NMR, and the products were characterized by an extensive NMR data set (¹H, ¹¹B, ¹³C, ²⁹Si, ¹¹⁹Sn NMR). Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis,Structure–Activity Relationship of Some New Triorganotin(IV) Derivatives of Dipeptides as Anti-Inflammatory Agents

Abstract

New triorganotin(IV) derivatives of dipeptides with general formulae, R₃Sn(HL), where R = Me and Ph, and HL is the monoanion of histidinylalanine and histidinylleucine, have been synthesized and characterized on the basis of infrared (IR), multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn), and ¹¹⁹Sn Mössbauer spectroscopic studies. These derivatives exhibit distorted trigonal-bipyramidal geometry around tin in which dipeptide anion acts as bidentate ligand coordinating through carboxyl oxygen and amino nitrogen. Ph₃Sn(HHis-Ala),

Ph₃Sn(HHis-Leu), and previously reported Ph₂Sn(His-Ala), Me₂Sn(His-Ala), n-Oct₂Sn(His-Ala), Me₂Sn(His-Leu), n-Oct₂Sn(His-Leu), Ph₃Sn(HTyr-Phe), Ph₂Sn(Tyr-Phe), Bu₂Sn-(Tyr-Phe), and n-Oct₂Sn(Tyr-Phe) along with standard drugs, viz. phenyl butazone and indomethacin were screened for in vivo anti-inflammatory activity and acute toxicity (LD₅₀). Diorganotin(IV) derivatives are more active than triorganotin(IV) derivatives. Me₂Sn(His-Leu) shows the highest activity.

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