Molybdenum and Tungsten Tricarbonyl Complexes with the Tripodal Ligands [ⁿBuSn(2-pyridyl)₃] and [RSn(methylthiomethyl)₃]

Abstract

The ligands [ n BuSn(2-pyridyl) 3 ] and [RSn(methylthiomethyl) 3 ] (R ) n Bu, Me) have been prepared in a one-pot, two-step procedure from the corresponding alkyltin trichloride and 2-pyridyl or methylthiomethyl carbanions. The reaction of these ligands with [M(CO) 3 (NCR) 3 ] (M ) Mo, W) afforded the tricarbonyl compounds [{ n BuSn(2-pyridyl) 3 }M(CO) 3 ] and [{RSn-(methylthiomethyl) 3 }M(CO) 3 ]. In addition to IR and NMR characterization, the structure of three of these new complexes was determined by single-crystal X-ray diffraction.

Main group pyridyl-based ligands; strategies to mixed metal complexes

“…Group 14 tris-2-pyridyl ligands are of two types, neutral [RE(2-py) 3 ] (10) (Fig. 12a, containing the group 14 elements (E) in the IV oxidation state) [14][15][16] and anionic [E(2-py) 3 ] À (11) (Fig. 12b, in which E is in the II oxidation state).…”

“…14b). 16 The structurally-characterised Pb II complex [E(2-py) 3 ]LiÁthf [11ÁLi(thf)] (Fig. 15) has proved to be too unstable to be employed as a source of the anion 11.…”

“…7 It is only relatively recently, however, that the first examples of tris-pyridyl ligands containing main group semi-metal or metal bridgehead atoms (E) have been introduced. [8][9][10][11][12][13][14][15][16][17][18] These species not only have greater ligand bites than their more traditional non-metallic counterparts, as a result of the greater E-C bond lengths, but the presence of a metallic element introduces (i) the possibility of anionic ('ate complexes) as well as neutral members of this class of ligands, (ii) the potential for variable oxidation states at the bridgehead atoms, and (iii) potential redox chemistry both at the bridgehead and between the bridgehead and N-coordinated metal. This review looks at the new range of tris-pyridyl ligand systems containing the heavier p-block elements now available, the similarities and differences of these to systems containing non-metallic bridgeheads and, most importantly, the way in which the metalbased ligand systems can be used to construct heterometallic complexes in a targeted manner.…”

Metal and ligand substitution of the aluminium tris-pyridyl ligands [RAl(2-py′)3]−(R = Et,nBu,sBu,tBu; 2-py′ = 2-pyridyl, 3-methyl-2-pyridyl, 5-methyl-2-pyridyl, 6-methyl-2-pyridyl)

“…The products 1-7 were isolated and handled with the aid of a nitrogen-filled glovebox (Saffron Scientific, Type b), equipped with Cu and molecular sieve columns. All 1 H and 13 C NMR spectra were recorded using a Bruker DPX 500 MHz NMR spectrometer. Both were referenced to the solvent peaks as an internal standard.…”

“…Together with others, we have been interested in metal-bridged relatives that incorporate heavier, more metallic atoms at the bridgehead (M). [7][8][9][10][11][12][13] This provides an extremely simple method by which heterometallic complexes with well-defined stoichiometries can be prepared (Scheme 1). 7,11, 12 The most obvious effect of the incorporation of larger bridgehead atoms is expansion of the ligand bite owing essentially to increased bridgehead-C pyridyl bond lengths.…”