Tungsten(VI) and Molybdenum(VI) Complexes with Soft Thioether Ligand Coordination – Synthesis, Spectroscopic and Structural Studies

Synthesis, properties and structural features of molybdenum(v) oxide trichloride complexes with neutral chalcogenoether ligands

“…18 The stabilising effect of two oxido-groups on molybdenum(VI) is shown by the successful isolation of [MoO 2 X 2 (dithioether)] (X = Cl or Br). 12,13 The limited affinity of the hard MoOCl 3 for the weaker donor monochalcogenoethers is reflected in the formation of 1 : 1 adducts, which achieve six-coordination by forming chloride bridges, as in [{MoOCl 2 (E'Me 2 )} 2 (µ-Cl) 2 ] (E′ = S, Se), rather than by coordinating a second neutral donor ligand. The same explanation accounts for the formation of oligomeric complexes, [(MoOCl 3 ) 2 (L-L)] n with o-C 6 H 4 (SeMe) 2 , o-C 6 H 4 (TeMe) 2 and MeTe(CH 2 ) 3 TeMe, postulated to have a structure with only one chalcogen donor atom on each molybdenum, and where six-coordination is achieved via bridging chlorides and bridging dichalcogenoethers (Scheme 1).…”

“…[4][5][6] The chemistry with neutral P-and As-donor ligands with Mo(V) has also been investigated, [7][8][9][10][11] but sulfur-based ligands were mostly represented by charged thiolate and dithiocarbamate ligands. [2][3][4] More recent work has reported a series of extremely moisture sensitive Mo(VI) complexes [MoO 2 X 2 (dithioether)] (X = Cl or Br; dithioether = RS(CH 2 ) 2 SR, R = Me, Et, i Pr), which have distorted octahedral structures with the sulfur donor atoms trans to MovO; 12,13 there are also some thia-macrocyclic analogues. 14,15 Complexes of the type [MoOCl 3 (dithioether)] were briefly described in the 1970's, characterised only by microanalysis and IR spectroscopy, but the structures and isomer(s) present were not established.…”

Thio- and seleno-ether complexes with Group 4 tetrahalides and tin tetrachloride: preparation and use in CVD for metal chalcogenide films

“…As possible CVD precursors we have specifically looked at ligands based upon the o-xylyl backbone, o-C 6 H 4 (CH 2 EMe) 2 (E = S or Se), which have given stable and soluble complexes with many late transition metal halides, 29 and also with Mo(VI) in the dinuclear metallocyclic [(MoO 2 Cl 2 ) 2 {l-o-C 6 H 4 (CH 2 SMe) 2 }] which has been structurally characterised. 32 We reasoned that in addition to forming well-defined precursor complexes, the o-xylyl-E groups should aid C-E bond fission, cf. the well known ease of cleavage of benzyl groups.…”

Six- and eight-coordinate thio- and seleno-ether complexes of NbF5and some comparisons with NbCl5 and NbBr5 adducts

“…Complexes of soft neutral thioether or selenoether ligands with hard oxophilic early transition metals in their highest oxidation states are relatively uncommon, and metal fluoride complexes are very rare. 1, 2 We have reported dithioether and diselenoether adducts of MoO 2 X 2 (X = Cl or Br), 3 WO 2 X 2 , 4 MCl 4 (M = Ti, Zr or Hf), 5, 6 VOX 3 (X = F or Cl (thioethers only)), 7 and VCl 4 , 7,8 all of which are extremely readily hydrolysed. Some of these complexes are single-source CVD precursors for metal dichalcogenide films.…”