Syntheses,Structures, and Reactivities of Two Chalcogen‐Stabilized Carbones

Electronic effects on the central carbon atom of carbone, generated by the replacement of the S^IV ligand of carbodisulfane (CDS) with other chalcogen ligands (Ph₂E, E=S or Se), were investigated. The carbones Ph₂E→C←SPh₂(NMe) [E=S( 1 ) or Se( 2 )] were synthesized from the corresponding salts, and their molecular structures and electronic properties were characterized. The carbone 2 is the first carbone containing selenium as the coordinated atom. DFT calculations revealed the electronic structures of 1 and 2 , which have two lone pairs of electrons at the carbon center. The trend in HOMO energy levels, estimated by cyclic voltammetry measurements, for the carbones and CDS follows the order of 2 > 1 >CDS. Analysis of a doubly protonated dication and trication complex revealed that the central carbon atom of 2 behaves as a four‐electron donor.     

Synthesis,Structure, and Reactivities of Iminosulfane‐ and Phosphane‐Stabilized Carbones Exhibiting Four‐Electron Donor Ability

Iminosulfane(phosphane)carbon(0) derivatives (iSPCs; Ar₃P→C←SPh₂(NMe); Ar=Ph ( 1 ), 4‐MeOC₆H₄ ( 2 ), 4‐(Me₂N)C₆H₄ ( 3 )) have been successfully synthesized and the molecular structure of 3 characterized. Carbone 3 is the first thermally and hydrolytically stable carbone stabilized by phosphorus and sulfur ligands. DFT calculations reveal the electronic structures of 1 – 3 , which have two lone pairs of electrons at the carbon center. First and second proton affinity values are theoretically calculated to be in the range of 286.8–301.1 and 189.6–208.3 kcal mol^?1, respectively. Cyclic voltammetry measurements reveal that the HOMO energy levels follow the order of 3 > 2 > 1 and the HOMO of 3 is at a higher energy than those of bis(chalcogenane)carbon(0) (BChCs). The reactivities of these lone pairs of electrons are demonstrated by the C‐diaurated and C‐proton‐aurated complexes. These results are the first experimental evidence of phosphorus‐ and sulfur‐stabilized carbones behaving as four‐electron donors. In addition, the reaction of hydrochloric salts of the carbones with Ag₂O gives the corresponding Ag^I complexes. The resulting silver(I) carbone complexes can be used as carbone transfer agents. This synthetic protocol can also be used for moisture‐sensitive carbone species.     

Complexes of Dichlorogermylene with Phosphine/Sulfoxide-Supported Carbone as Ligand

Due to their remarkable electronic features, recent years have witnessed the emergence of carbones L₂C, which consist in two donating L ligands coordinating a central carbon atom bearing two lone pairs. In this context, the phosphine/sulfoxide-supported carbone 4 exhibits a strong nucleophilic character, and here, we describe its ability to coordinate dichlorogermylene. Two original stable coordination complexes were obtained and fully characterized in solution and in the solid state by NMR spectroscopy and X-ray diffraction analysis, respectively. At 60 °C, in the presence of 4, the Ge(II)-complex 5 undergoes a slow isomerization that transforms the bis-ylide ligand into an yldiide.     

From an Isolable Acyclic Phosphinosilylene Adduct to Donor‐Stabilized SiE Compounds (E=O,S, Se)

Reaction of the arylchlorosilylene‐NHC adduct ArSi(NHC)Cl [Ar=2,6‐Trip₂C₆H₃; NHC=(MeC)₂(NMe)₂C:] 1 with one molar equiv of lithium diphenylphosphanide affords the first stable NHC‐stabilized acyclic phosphinosilylene adduct 2 (ArSi(NHC)PPh₂), which could be structurally characterized. Compound 2 , when reacted with one molar equiv selenium and sulfur, affords the silanechalcogenones 4 a and 4 b (ArSi(NHC)(?E)PPh₂, 4 a : E=Se, 4 b : E=S), respectively. Conversion of 2 with an excess of Se and S, through additional insertion of one chalcogen atom into the Si?P bond, leads to 3 a and 3 b (ArSi(NHC)(?E)‐E‐P(?E)Ph₂, 3 a : E=Se, 3 b : E=S), respectively. Additionally, the exposure of 2 to N₂O or CO₂ yielded the isolable NHC‐stabilized silanone 4 c , Ar(NHC)(Ph₂P)Si?O.     

Ligating properties oftert-phosphine/arsine sulphides or selenides,Part IX. Preparation and spectroscopic studies of copper(I)/copper(II) complexes with bis(—phosphine chalcogenides)

Summary The analytical, molar conductance and spectroscopic studies of new complexes of copper(I) and copper(II) with bis(—phosphine chalcogenides), Ph₂P(E)(CH₂)_n-P(E)Ph₂(L-L) are reported. The complexes are of the types: (a) [CuX(L-L)](X, n, E: Cl, 2–4, Br, 2, S; Cl, Br, 1, Se); (b) [Cu₂X₂(L-L)] (X, n, E: Cl, Br, 2, 3, Se) and (c) [CuCl₂(L-L)] (n, E: 2, 3, S). Possible structures have been derived.     

Sterically Crowded peri‐Substituted Naphthalene Phosphines and their PV Derivatives

Three sterically crowded peri‐substituted naphthalene phosphines, Nap[PPh₂][ER] (Nap=naphthalene‐1,8‐diyl; ER=SEt, SPh, SePh) 1–3 , which contain phosphorus and chalcogen functional groups at the peri positions have been prepared. Each phosphine reacts to form a complete series of P^V chalcogenides Nap[P(E′)(Ph₂)(ER)] (E′=O, S, Se). The novel compounds were fully characterised by using X‐ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. X‐ray data for 1 , 2 , n O , n S , n Se (n=1–3) are compared. Eleven molecular structures have been analysed by naphthalene ring torsions, peri‐atom displacement, splay angle magnitude, X???E interactions, aromatic ring orientations and quasi‐linear arrangements. An increase in the congestion of the peri region following the introduction of heavy chalcogen atoms is accompanied by a general increase in naphthalene distortion. P???E distances increase for molecules that contain bulkier atoms at the peri positions and also when larger chalcogen atoms are bound to phosphorus. The chalcogenides adopt similar conformations that contain a quasi‐linear E???P? C fragment, except for 3 O , which displays a twist‐axial‐twist conformation resulting in the formation of a linear O???Se? C alignment. Ab initio MO calculations performed on 2 O , 3 O , 3 S and 3 Se reveal Wiberg bond index values of 0.02 to 0.04, which indicates only minor non‐bonded interactions; however, calculations on radical cations of 3 O , 3 S and 3 Se reveal increased values (0.14–0.19).     

Formation of carbonylrhenium cryptates with alkali metal cations: Coordination chemistry studies of [Ph2P(E)NP(E)Ph2], E = O,S, Se towards ReBr(CO)5

Reaction of ReBr(CO)₅ with Li[Ph₂P(O)NP(O)Ph₂] afforded the cryptate Li[Re₂(CO)₆{μ-Ph₂P(O)NP(O)Ph₂-κ²O,O’}₃]; whereas K[Ph₂P(O)NP(O)Ph₂] reacted with ReBr(CO)₅ to give K[Re₂(CO)₆{μ-Ph₂P(O)NP(O)Ph₂-κ²O,O′}{Ph₂P(O)NP(O)Ph₂-κ²O,O′}₂]. Other chalcogen ligands’ salts M[Ph₂P(E)NP(E)Ph₂], E = Se and S, M = K and Li gave dirhenium carbonyls with bromido and Ph₂P(E)NP(E)Ph₂, E = Se or S bridges upon reaction with ReBr(CO)₅.     

Tellurium(II) and tellurium(IV) complexes of phosphine chalcogenide ligands,synthesis and X-ray structures

Reaction of TeX₄ (X = Cl or Br) with 2 mol. equiv. of OPR₃ (R = Me, Et or Ph) gives the distorted octahedral cis-[TeX₄(OPR₃)₂], while the bidentates Ph₂P(E)(CH₂)_nP(E)Ph₂ (E = O, n = 1 or 2; E = S, n = 1) give the six-coordinate [TeX₄{Ph₂P(E)(CH₂)_nP(E)Ph₂}]. These species have been characterised spectroscopically (via ¹H and ³¹P{¹H} NMR and IR) and by crystallographic analyses on cis-[TeBr₄(OPPh₃)₂], [TeCl₄{Ph₂P(O)CH₂P(O)Ph₂}] and [TeBr₄{Ph₂P(S)CH₂P(S)Ph₂}]. The TeX₄ (X = Cl or Br) are reduced by Ph₂P(S)(CH₂)₂P(S)Ph₂ and Ph₂P(Se)CH₂P(Se)Ph₂, giving the planar, four-coordinate Te(II) species [Te{Ph₂P(S)(CH₂)₂P(S)Ph₂}₂]²⁺ (isolated as [(TeCl₅)₂{μ-Ph₂P(S)(CH₂)₂P(S)Ph₂}]^2? and [TeBr₆]^2? salts) and [TeBr₂{Ph₂P(Se)CH₂P(Se)Ph₂}], all of which have also been identified crystallographically. On the basis of the structural data the Te-based lone pair associated with the Te(IV) species is assumed to occupy the 5s orbital, whereas in the Te(II) complexes the planar coordination is consistent with the two stereochemically active lone pairs occupying the axial sites.     

Carbodicarbenes and Related Divalent Carbon(0) Compounds

Quantum‐chemical calculations using DFT and ab initio methods have been carried out for fourteen divalent carbon(0) compounds (carbones), in which the bonding situation at the two‐coordinate carbon atom can be described in terms of donor–acceptor interactions L→C←L. The charge‐ and energy‐decomposition analysis of the electronic structure of compounds 1 – 10 reveals divalent carbon(0) character in different degrees for all molecules. Carbone‐type bonding L→C←L is particularly strong for the carbodicarbenes 1 and 2 , for the “bent allenes” 3 a , 3 b , 4 a , and 4 b , and for the carbocarbenephosphoranes 7 a , 7 b , and 7 c . The last‐named molecules have very large first and large second proton affinities. They also bind two BH₃ ligands with very high bond energies, which are large enough that the bis‐adducts should be isolable in a condensed phase. The second proton affinities of the complexes 5 , 6 , and 8 – 10 bearing CO or N₂ as ligand are significantly lower than those of the other molecules. However, they give stable complexes with two BH₃ ligands and thus are twofold Lewis bases. The calculated data thus identify 1 – 10 as carbones L→C←L in which the carbon atom has two electron pairs. The chemistry of carbones is different from that of carbenes because divalent carbon(0) compounds CL₂ are π donors and thus may serve as double Lewis bases, while divalent carbon(II) compounds are π acceptors. The theoretical results point toward new directions for experimental research in the field of low‐coordinate carbon compounds.     

Synthesis and Characterisation of New Metallacycles Containing [Ph2P(E)NP(E)Ph2]− (E = S OR Se) Ligands

Abstract

Reaction of [Ph₂P(E)NP(E)Ph₂]^? (E = S or Se) with a series of late transition-metal dimers, in thf or MeOH, leads to facile bridge cleavage and formation of new mononuclear compounds.     

Distinguishing carbones from allenes by complexation to AuCl

Quantum chemical calculations have been performed for the dicoordinated carbon compounds C(PPh(3))(2), C(NHC(Me))(2), R(2) C=C=CR(2) (R = H, F, NMe(2)), C(3)O(2), C(CN)(2)(-) and N-methyl-substituted N-heterocyclic carbene (NHC(Me)). The geometries of the complexes in which the dicoordinated carbon molecules bind as ligands to one and two AuCl moieties have been optimized and the strength and nature of the metal-ligand interactions in the mono- and diaurated complexes were investigated by means of energy decomposition analysis. The goal of the study is to elucidate the differences in the chemical behavior between carbones, allenes and carbenes. The results show that carbones bind one and two AuCl species in η(1) fashion, whereas allenes bind them in η(2) fashion. Compounds with latent divalent carbon(0) character can coordinate in more than one way, with the dominant mode indicating the degree of carbone or allene character. The calculated structures of the mono- and diaurated tetraaminoallenes (TAAs) reveal that TAAs exhibit a chameleon-like behavior: The bonding situation in the equilibrium structure is best described as allene [(R(2)N)(2)]C=C=C[(NR(2))(2)] in which the central carbon atom is a tetravalent C(IV) species, but the reactivity suggests that TAAs should be considered as divalent C(0) compounds C{C[(NR(2))(2)]}(2), that is, as "hidden" carbones. Carbon suboxide binds one AuCl preferentially in the η(1) mode, whereas the equilibrium structures of the η(1)- and η(2)-bonded diaurated complex are energetically nearly degenerate. The doubly negatively charged isoelectronic carbone C(CN)(2)(2-) binds one and two AuCl very strongly in characteristic η(1) fashion. The N-heterocyclic carbene complex, [NHC(Me)(AuCl)], possesses a high bond dissociation energy (BDE) for the splitting off of AuCl. The diaurated NHC adduct, [NHC(Me)(AuCl)(2)], has two η(1)-bonded AuCl moieties that exhibit aurophilic attraction, which yield a moderate bond strength that might be large enough for synthesizing the complex. The BDE for the second AuCl in [NHC(Me)(AuCl)(2)] is clearly smaller than the values for the second AuCl in doubly aurated carbone complexes.     

Hydrophosphination of CO2 and Subsequent Formate Transfer in the 1,3,2‐Diazaphospholene‐Catalyzed N‐Formylation of Amines

Hydrophosphination of CO₂ with 1,3,2‐Diazaphospholene (NHP‐H; 1 ) afforded phosphorus formate (NHP‐OCOH; 2 ) through the formation of a bond between the electrophilic phosphorus atom in 1 and the oxygen atom from CO₂, along with hydride transfer to the carbon atom of CO₂. Transfer of the formate from 2 to Ph₂SiH₂ produced Ph₂Si(OCHO)₂ ( 3 ) in a reaction that could be carried out in a catalytic manner by using 5 mol % of 1 . These elementary reactions were applied to the metal‐free catalytic N‐formylation of amine derivatives with CO₂ in one pot under ambient conditions.     

Sekundäre Phosphinchalkogenide. VII. Synthese von Bis(tert.-butylphosphino)ethan,ButHPCH2CH2PHBut,und 1-tert.-Butylphosphino-2-diphenylphosphino-ethan,Ph2PCH2CH2PHBut,sowie deren sekundäre Phosphinchalkogenide

Secondary Phosphine Chalcogenides. VII. Synthesis of Bis(tert.-butylphosphino)thane, Bu^tHPCH₂CH₂PHBu^t, and 1-tert.-Butylphosphino-2-diphenylphosphinoethane, Ph₂PCH₂CH₂PHBu^t, as well as their Secondary Phosphine Chalcogenides The reaction of Cl₂PCH₂CH₂PCl₂ with Bu^tMgCl gives Bu^tClPCH₂CH₂PClBu^t which is either hydrolysed to yield Bu^tH(O)PCH₂CH₂P(O)HBu^t or reduced to give Bu^tHPCH₂CH₂PHBu^t. This phosphine reacts with sulfur or selenium to give Bu^tH(E)PCH₂CH₂P(E)HBu^t (E = S, Se). Treatment of Ph₂PCH₂CH₂Cl with LiPHBu^t results Ph₂PCH₂CH₂PHBu^t which is oxidized to give Ph₂(E)PCH₂CH₂P(E)HBu^t (E = O, S, Se). The Ph₂P group appears to be oxidized primarily. The compounds obtained are characterized by means of I.R. ¹H and ³¹P-N.M.R. spectroscopy.     

Synthesis,characterization and biological activity of diphenyltin(IV) complexes of N‐(3,5‐dibromosalicylidene)‐α‐amino acid and their diphenyltin dichloride adducts

Diphenyltin(IV) complexes of N‐(3,5‐dibromosalicylidene)‐α‐amino acid, Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂ CH?NCH(R)COO] (where R = H, Me, i‐Pr, Bz), and their 1:1 adducts with diphenyltin dichloride, Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(R)COO]·Ph₂SnCl₂, have been synthesized and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectra. The crystal structure of Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(i‐Pr)COO] shows a distorted trigonal bipyramidal geometry with the axial locations occupied by a carboxylate–oxygen and a phenolic–oxygen atom of the ligand, and that of Ph₂Sn[3,5‐Br₂‐2‐OC₆H₂CH?NCH(i‐Pr)COO]·Ph₂SnCl₂ reveals that the two tin atoms are joined via the carbonyl atom of the ligand to form a mixed organotin binuclear complex. Bioassay indicates that the compounds possess better cytotoxic activity against three human tumor cell lines (HeLa, CoLo205 and MCF‐7) than cis‐platin and moderate antibacterial activity against two bacteria (E. coli and S. aureus). Copyright © 2005 John Wiley & Sons, Ltd.     

Über Polygermane. V. Octaphenyl-selenatetragermacyclopentan,Kristallstruktur und Schwingungsspektren

On Polygermanes. V. Octaphenyl-selenatetragermacyclopentane, Crystal Structure and Vibrational Spectra The crystal structure of the title compound (Ph₂Ge)₄Se has been determined and refined to a R of 0.037. The five membered ring Ge₄Se exhibits twist conformation (C₂ symmetry) and approximates planarity. The arrangement of the phenyl substituents is isoclinic towards the ring and symperiplanar in two sets among themselves. Distances: Ge—Ge 244.8 (1) and 243.7 (1) pm, Ge—Se 237.3 (1) pm; angle Ge—Se—Ge 106.3 (1°). The packing of the (Ph₂Ge)₄Se molecules resembles a body-centred sphere packing with coordination number (8+4). The complete vibrational spectra of the compounds (Ph₂Ge)₄X with X = O, S, and Se are given and assigned. Domains for the 9 normal vibrations of the five membered cycles Ge₄X are discussed.     

Cu(I) and Ag(I) complexes of chalcogenide derivatives of the organometallic ligand dppf and the dppa analogue

New Cu(I) and Ag(I) complexes were prepared by reaction of [M(NCCH₃)₄][X] (M = Cu or Ag; X = BF₄ or PF₆) with the bidentate chalcogenide ligands Ph₂P(E)NHP(E)Ph₂ (E = S, S₂dppa; E = Se, Se₂dppa), and dpspf (1,1′-bis(diphenylselenophosphoryl)ferrocene). Copper and silver behaved differently. While three molecules of either S₂dppa and Se₂dppa bind to a distorted tetrahedral Cu₄ cluster, with deprotonation of the ligand, 1:2 complexes of the neutral ligands are formed with Ag(I), with a tetrahedral coordination of the metal. The [Cu₄{Ph₂P(Se)NP(Se)Ph₂}₃]⁺ clusters assemble as dimers, held together by weak Se?Se distances interactions. Another dimer was observed for the [Ag(dpspf)]⁺ cation, with two short Ag?Se distances. DFT and MP2 calculations indicated the presence of attracting interactions, reflected in positive Mayer indices (MI). The electrochemistry study of this species showed that both oxidation and reduction took place at silver.     

Synthesis,structural characterization,and photophysical studies of hexanuclear gold(I) chalcogenido complexes

A hexanuclear gold(I) selenido cluster and its sulfido counterpart, [Au₆{μ‐Ph₂PN(CH₂‐o‐Py)PPh₂}₃(μ₃‐E)₂](ClO₄)₂ (E = S, Se), with bridging bis(diphenylphosphino)amine ligands were synthesized and characterized. The X‐ray crystal structure of the selenido cluster was determined, with the gold core possessing a distorted heterocubane structure. Intramolecular aurophilic interactions with short Au(I)?Au(I) contacts of around 3.09–3.13 Å were observed. The complexes were found to emit strongly in the solid state with orange to red emission colors. Their electronic absorption and emission properties were also investigated.     

Organotin(IV) complexes derived from proteinogenic amino acid: synthesis,structure and evaluation of larvicidal efficacy on Anopheles stephensi mosquito larvae

Five new organotin(IV) complexes of composition [Bz₂SnL¹]_n ( 1 ), [Bz₃SnL¹H⋅H₂O] ( 2 ), [Me₂SnL²⋅H₂O] ( 3 ), [Me₂SnL³] ( 4 ) and [Bz₃SnL³H]_n ( 5 ) (where L¹ = (2S )‐2‐{[(E )‐(4‐hydroxypentan‐2‐ylidene)]amino}‐4‐methylpentanoate, L² = (rac )‐2‐{[(E )‐1‐(2‐hydroxyphenyl)methylidene]amino}‐4‐methylpentanoate and L³ = (2S )‐ or (rac )‐2‐{[(E )‐1‐(2‐hydroxyphenyl)ethylidene]amino}‐4‐methylpentanoate) were synthesized and characterized using ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR and infrared spectroscopic techniques. The crystal structure of 2 reveals a distorted trigonal‐bipyramidal geometry around the tin atom where the oxygen atoms of the carboxylate ligand and a water ligand occupy the axial positions, while the three benzyl ligands are located at the equatorial positions. On the other hand, the analogous derivative of enantiopure L³H ( 5 ) consists of polymeric chains, in which the ligand‐bridged tin atoms adopt the same trans ‐Bz₃SnO₂ trigonal‐bipyramidal configuration and are now coordinated to a phenolic oxygen atom instead of H₂O. In 2 , the OH hydrogen of the ketoimine substituent has moved to the nearby nitrogen atom while in the salicylidene derivative 5 , the OH is located almost midway between the phenolic oxygen atom and the nitrogen atom of the CN group. For the dibenzyltin derivative 1 , a polymeric chain structure is observed as a result of a long intermolecular Sn⋅⋅⋅O bond involving the exocyclic carbonyl oxygen atom from the tridentate ligand of a neighbouring tin‐complex unit. The tin atom in this complex has distorted octahedral coordination geometry. In contrast, the racemic dimethyltin(IV) complexes 3 and 4 display discrete monomeric structures with a distorted octahedral‐ and trigonal‐bipyramidal geometry, respectively. The structures show that the coordination mode of the Schiff base ligand depends primarily on the number of bulky benzyl ligands (R) at the tin atom, as indeed found in the structures of related complexes where R = phenyl. With three bulky R groups, the tridentate chelating O,N,O coordination mode is preferred, whereas with fewer or less bulky R ligands, only the carboxylate and hydroxy groups are involved, which leads to polymers. Larvicidal efficacies of two of the new tribenzyltin(IV) complexes ( 2 and 5 ) were assessed on the second larval instar of Anopheles stephensi mosquito larvae and compared with two triphenyltin(IV) analogues, [Ph₃SnL¹H]_n and [Ph₃SnL³H]_n . The results demonstrate that the compounds containing Sn–Ph ligands are more effective than those with Sn–Bz ligands. Copyright © 2016 John Wiley & Sons, Ltd.     

Chlorodiphenyltin(IV) and triphenyltin(IV) complexes of N-alkylated 2-amino-1-cyclopentene-1-carbodithioic acids: synthesis, spectroscopic characterization and X-ray studies

Four new complexes, [Ph₃Sn(isopropylACDA)] (1), [Ph₂SnCl(isopropylACDA)] (2), [Ph₃Sn(secbutylACDA)] (3), and [Ph₂SnCl(secbutylACDA)] (4), have been prepared from reaction between N-alkylated 2-amino-1-cyclopentene-1-carbodithioic acids (ACDA) with Ph₂SnCl₂ and Ph₃SnCl in 1:1 ratio. All complexes are characterized by FTIR, multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn) and mass spectrometry. In all complexes, the S–H proton has been removed and coordination takes place through the carbodithioate moiety. The ¹¹⁹Sn NMR data are consistent with five coordination of tin atom in solution. Complexes 2, 3, and 4 have also been confirmed by single X-ray crystallography. All three crystals are triclinic with space group P − 1. In complexes 2 and 4, the geometry around tin atom is distorted trigonal bipyramidal while in 3 the geometry is in between distorted tetrahedral and trigonal bipyramid. In all three structures, ligands are asymmetrically coordinated to tin atom. In addition, crystal structures are further stabilized by N–H···S hydrogen bonding.     

Preparation and structures of [2‐(dimethylamino)phenyl]diorganotin(IV) acetates substituted with organophosphorus groups in the α‐position of the acetate ligand

Organotin(IV) carboxylates R₂L^NCSnOC(O)CH₂P(E)Ph₂, where L^NC is an N‐chelating 2‐(dimethylamino)phenyl group, and R/E = Ph/void (1a), Ph/O (1b), Ph/S (1c), Me/void (2a), Me/O (2b) and Me/S (2c), were synthesized, characterized by ¹H, ¹³C, ³¹P and ¹¹⁹Sn NMR, IR and MS spectra, and the solid‐state structures of 1b, 1c, 2b and 2c were determined by single‐crystal X‐ray diffraction. Spectral and structural data showed that the compounds are monomeric in CDCl₃ solution and the solid state, with the organophosphorus groups in the α‐position of the monodentate carboxylate ligands not interacting with the tin atom. Copyright © 2005 John Wiley & Sons, Ltd.