Syntheses and Structures of Methyltris(pyrazolyl)silane Complexes of the Group 6 Metals

Abstract

The methyltris(3,5-dimethylpyrazolyl)silane ligand, TpsMe2, was readily prepared by the metathesis reaction of methyltrichlorosilane with 3 equiv of lithium 3,5-dimethylpyrazolate. The octahedral tricarbonyl complexes (TpsMe2)M(CO)3 were synthesized either by ligand exchange with the labile nitrile adducts M(CO)3(NCR)3 (M = Cr, Mo, R = Me; M = W, R = Et) or thermally by direct substitution on the hexacarbonyls M(CO)6 (M = Cr, Mo). The three new complexes were characterized by a combination of analytical and spectroscopic techniques, including electrospray ionization mass spectrometry and single-crystal X-ray diffraction. They are all isostructural and display in the solid state the expected distorted octahedral geometries with facially coordinated tris(pyrazolyl)silane ligands. Crystallographic data were used to calculate the ligand cone angles (251-264 degrees) in (TpsMe2)M(CO)3 and also to estimate a value of 1.59 A for the covalent radius of octahedral W(0).

Tris(pyrazolyl)methane Ligands: Syntheses and Structures of Monometallic and Metallodendritic Complexes

“…[11] The titanium examples are much more limited, [12] although some interesting heteroscorpionate-like complexes have recently been reported. [13] In the case of palladium(), bis(pyrazolyl)-methane as well as tris(pyrazolyl)methane compounds have been described.…”

Isolation and authentication of a sodium bispyrazolylaluminate

“…The number of complexes known with these ligands is vast and spans to virtually all metals in the periodic chart [1]. Several anoalogs have been prepared with the replacement of B by other main group element of the groups 13 (Ga, In) [2], 14 (C [3] and Si [4], Ge and Sn [5]) and 15 (P) [6], and for several of these species their coordination chemistry has been explored. It came to our attention that the pyrazolylaluminates have not been convincingly isolated and authenticated, despite their desirable use in the preparation of novel mixed main group-transition metal complexes with potential applications, e.g., in homogenous catalysis.…”

New N , N , O , O functionalized heteroscorpionate ligands and related Zn(II) and Cd(II) derivatives

“…Modifications of poly(pyrazolyl)borates can be made by replacement of the boron bridging atom with carbon [4], silicon [5], or phosphorus [6]. Other important variations can be effected by replacing the pyrazolyl with triazolyl [7], imidazolyl [8], and methimazolyl moieties [9] or by changing the substituents on the heterocyclic ring.…”