Chemistry of a Novel Family of Tridentate Alkoxy Tin(II) Clusters

Abstract

The chemical interconversions observed for a novel family of trihydroxymethyl ethane (THME-H(3)) ligated Sn(II) compounds have been determined using single-crystal X-ray and (119)Sn NMR experiments. (mu-THME)(2)Sn(3) (1) was isolated from the reaction of 3 equiv of [Sn(NR(2))(2)](2) (R = SiMe(3)) with 4 equiv of THME as a unique trinuclear species capped above and below the plane of Sn atoms by two THME ligands. Upon reaction with "Sn(NR(2))(2)", compound 1 rearranged to yield another novel molecule [(mu-THME)Sn(2)(NR(2))](2) (2). Compound 2 could also be formed directly from the stoichiometric mixture of THME-H(3) and [Sn(NR(2))(2)](2). Further studies revealed that 1 would also rearrange in the presence of Sn(OR)(2) to form [(mu-THME)Sn(2)(mu-OR)](2) [OR = OMe (3), OCH(2)Me (4), OCH(2)CH(Me)CH(2)CH(3) (5), OCH(2)CMe(3) (6, ONep), OC(6)H(5) (7, not structurally characterized), OC(6)H(4)Me-3 (8), OC(6)H(4)Me-2 (9), OC(6)H(3)(Me)(2)-2,6 (10), OC(6)H(3)(CHMe(2))(2)-2,6 (11). Additionally, 3-11 could by synthesized from the reaction of 2 and the appropriate H-OR. (119)Sn solution NMR studies of 2-11, in THF-d(8), indicate that an equilibrium between the parent complex and its disassociation products (1 and the free parent Sn alkoxy or amide precursor) exists at room temperature. This is a likely reason behind the ease of interconversion observed for 1. The generality of this exchange was further verified through the reaction of 1 with [Ti(mu-ONep)(ONep)(3)](2), which led to the isolation of (mu-ONep)(2)Sn(3)(mu-THME)(2)Ti(ONep)(2) (12). For 12, the solid-state structure was maintained in solution with no indication of an equilibrium.

Dihydrogen Tetrametaphosphate, [P4O12H2]2–: Synthesis, Solubilization in Organic Media, Preparation of its Anhydride [P4O11]2– and Acidic Methyl Ester, and Conversion to Tetrametaphosphate Metal Complexes via Protonolysis

“…As the reaction generates only the volatile HN(SiMe 3 ) 2 as byproduct, the PPN salt of 4 was easily isolated as analytically pure solid with the formula [PPN] Previous reports of tin(II) in a similar C 4v all-oxygen binding site were focused upon tungstostannate(II) heteropolyanions 26 and tridentate alkoxyl tin(II) clusters. 27 In fact, the solid-state tin(II) oxide SnO has tin(II) in nearly an identical C 4v environment consisting of four oxide ions as reported by Moore and Pauling, 28 making 4 an excellent molecular mimic of a known solid oxide material. To the best of our knowledge, 4 also represents the first example of κ 4 tetrametaphosphate coordination to a metal.…”

“…Previous reports of tin­(II) in a similar C 4 v all-oxygen binding site were focused upon tungstostannate­(II) heteropolyanions and tridentate alkoxyl tin­(II) clusters . In fact, the solid-state tin­(II) oxide SnO has tin­(II) in nearly an identical C 4 v environment consisting of four oxide ions as reported by Moore and Pauling, making 4 an excellent molecular mimic of a known solid oxide material.…”

Isolation and characterisation of transition and main group metal complexes supported by hydrogen-bonded zwitterionic polyphenolic ligandsElectronic supplementary information (ESI) available: full synthetic and spectroscopic details. See http://www.rsc.org/suppdata/cc/b3/b303618a/

“…The monomeric nature of 4 is noteworthy considering the tendency of Sn (II) complexes containing tris-alkoxide ligands to form polymetallic clusters. 6 As with complexes 3, the three arms of the trisphenolate ligand in 4, are orientated in a C 3symmetric propeller arrangement in the solid state, but unlike 3a, the 1 H NMR spectrum of 4 shows only a single resonance for the CH 2 protons, indicating that rapid inversion of the structure occurs at room temperature. As a consequence of chelation by HL 22 , the pyramidal geometry at Sn (II) is reinforced, and the metal centre lies out of the plane of the three phenolic oxygen atoms by 1.259 Å.…”

Precise Steric Control over 2D versus 3D Self-Assembly of Antimony(III) Alkoxide Cages through Strong Secondary Bonding Interactions

“…Noting this, we have designed a rigid antimony alkoxide cage (Scheme ) that is anticipated to facilitate three SBIs at the antimony center with one opposite to each primary bond which can lead to the predictable self-assembly of 2D bilayers when they arrange in an antiparallel fashion. It is notable that this type of triol has been used to support many different metal clusters; − however, with phosphorus and arsenic, the anticipated caged structure is obtained …”