Tin(ii) fluoride vs. tin(ii) chloride – a comparison of their coordination chemistry with neutral ligands

Abstract

Reaction of SnF2 in MeOH with the appropriate neutral N- or O-donor ligands produces [SnF(2,2'-bipy)]2SnF6, [SnF(1,10-phen)]2SnF4 and [SnF2(L)] L = Me3PO, dmso or pyNO). The X-ray structures of [SnF(2,2'-bipy)]2SnF6, [SnF(1,10-phen)]2SnF4 and [SnF2(dmso)], reveal trigonal pyramidal Sn(II) cores with longer fluorine bridges completing distorted 5- or 6-coordination. Attempts to prepare SnF2 adducts with various phosphine or diphosphine ligands in MeCN failed, whilst in CH2Cl2 solution complex reactions involving the solvent occurred. The NHC, 1,3-(2,6-di-isopropylphenyl)imidazol-2-ylidene (IDiPP) and SnF2 produced the imidazolium salt, [IDiPPH]SnF3, the crystal structure of which revealed the first example of a discrete trifluorostannate(II) ion. In contrast, diphosphine complexes of tin(II) chloride formed readily, including [SnCl2{Me2P(CH2)2PMe2}], [SnCl2{o-C6H4(PMe2)2}], [SnCl2{o-C6H4(PPh2)2}] and [(SnCl2)2(μ-Ph2P(CH2)2PPh2)], which were characterised by X-ray crystallography. The structures of [SnCl2{Me2P(CH2)2PMe2}] and [SnCl2{o-C6H4(PMe2)2}] reveal chloride-bridged dimers, but [SnCl2{o-C6H4(PPh2)2}], although also dimeric, has very asymmetric diphosphine coordination best described as κ(1). The structures of [(SnCl2)2(μ-Ph2P(CH2)2PPh2)] and of [SnCl{o-C6H4(AsMe2)2}]SnCl3 reveal trigonal pyramidal cores, but with longer Sn···Cl bridges affording polymeric structures. The synthesis of [SnCl2(R3EO)2] (R = Ph, E = P or As; and R = Me, E = P) are also reported, along with the structure of [SnCl2(Me3PO)2], which contains distorted tetragonal pyramidal Sn(II) coordination. X-ray structures are also reported for [(PMe3)2CH2][SnCl3]2 and [Ph2P(H)(CH2)2P(H)Ph2][SnCl3]2, obtained as by-products from the attempts to synthesise phosphine complexes, as well as [(o-C6H4(PMe2)2CH2]I2. All complexes were characterised by microanalysis, IR and multinuclear NMR spectroscopy ((1)H, (19)F{(1)H}, (31)P{(1)H } and, where solubility allowed, (119)Sn). Comparisons are drawn with corresponding Sn(IV) and Ge(II) complexes.

Different Complexation Behavior of P‐Functionalized Ferrocene Derivatives Towards SnCl2, SnCl4 and SnPh2Cl2: Auto‐ionization and Redox‐Type Reactions

“…Stalke et al employedaN,P-chelating ligand to obtain compound A, [4] while recently,R oesky et al describedthe Lewis base-mediated auto-ionization of SnCl 2 ,i n the presence of the neutral 2,6-diacetylpyridinebis(2,6-diisopropylanil) (Diimp) ligand giving B. [5] As imilar approachw as used by Jambor et al for the synthesis of C. [1h] Auto-ionization of SnCl 2 was also achieved by employing chelating arsine ligands as well as crown ethers and cryptands providing compounds D, [6] E, [7] F, [8] and G-I. [9] Ferrocene (Fc) has becomeapopular backbone for av ariety of chelate ligands because the presence of aF cu nit provides i) ac onvenient 3D environment for buildingv ariousc helating structures,i i) the possibility of planar chirality (ina ddition to atom chirality in the side branches), and iii)awell-definede lectrochemical response sensitive to the changesi nt he ligating branches (conformation,c oordination, donor-acceptor and Lewisa cid-base interactions).…”

Coordination chemistry of the main group elements with phosphine, arsine and stibine ligands

“…(Fig. 55); all are weakly associated into dimers via chlorine bridges [309]. The product of reacting SnCl 2 and Ph 2 P(CH 2 ) 2 PPh 2 , irrespective of the ratio of reactants used, is [(SnCl 2 ) 2 {-Ph 2 P(CH 2 ) 2 PPh 2 }], again with a pyramidal PCl 2 core linked into chains via chlorine bridges and with the diphosphine cross-linking the chains (Fig.…”

“…Attempts to prepare phosphine complexes of SnF 2 either by direct reaction with a suspension of SnF 2 in MeCN, or by displacement of dmso from [SnF 2 (dmso)] failed [309]. In CH 2 Cl 2 solution, mixtures of products slowly formed which were mainly phosphonium salts from reaction of the phosphine with the solvent.…”

“…56) }] some cooling of the solution was necessary to resolve the satellites. The other complexes seemed to be exchanging in solution even at low temperatures, and a combination of exchange processes and poor solubility prevented observation of 119 Sn resonances for any of these compounds [309].…”

“…View of the structure of [{SnCl2{o-C6H4(PMe2)2}}2] redrawn from Ref. [309]. with distorted environments about the central arsenics; there is no vacant vertex which could be occupied by the arsenic (on AsX 3 ) lone pair, but distortions in the bond lengths and angles suggest the lone pair may be localised in the direction of one AsX 3 triangular face [325] centres with anti-disposed PMe 3 groups axial, weakly associated into polymer chains via long Sb-I contacts [329].…”