Theoretical investigation of M≡E bonds in transition metal–ylidyne complexes trans-[H(PMe3)4M≡ER] (M = Mo, W; E = Si, Ge, Sn, Pb; R = Mes, Xylyl)

Synthesis and Reactivity of an Iron-Tin Complex with Adjacent Stannylidyne and Ferriostannylene Units

Heavier transition metal carbyne analogs hold significant potential for cooperative activation of small molecules. However, complexes containing more than one heavier tetrylidyne ligand RE (E = Si, Ge, Sn, Pb) are rare due to the high oligomerization tendency of RE ligands. In this study, we describe the complex [Fe(SnAr')2] (1; Ar' = 2,6-Dipp2-C6H3, Dipp = 2,6-iPr2-C6H3), which features adjacent Fe-Sn single and double bonds. Complex 1 exhibits versatile reactivity with transition metal and main group compounds. Treatment of complex 1 with Ni(COD)2 (COD = 1,5-cyclooctadiene) yields the tetranuclear complex [Fe(μ-SnAr')2Ni] (2), characterized by an unusual "push-pull" interaction between nickel(0) and the two coordinating Sn atoms, as revealed by quantum chemical studies. The reaction of complex 1 with AlBr3 results in Al-Br bond cleavage and Ar' migration to aluminum. CH3I adds oxidatively to the Sn atom that is singly bonded to Fe, while PMe3 coordinates to Fe, inducing reversible cleavage of the Fe═Sn double bond. In addition, complex 1 activates inorganic molecules. CO2 undergoes disproportionation to produce a carbonate-bridged Ar'Sn(μ-OCO2)SnAr' ligand, whereas CS2 is reductively coupled to form an ethylene tetrathiolate ligand ([C2S4]4-). The reaction with white phosphorus (P4) generates an unusual Ar'P4Sn2Ar' ligand. This multifaceted reactivity illustrates the behavior of the Fe and Sn sites in complex 1, suggesting that complexes of this type are promising reagents for small molecule activation.

Dispersion-Corrected Relativistic Density Functional Theory (DFT) Calculations of Structure and (119)Sn Mössbauer Parameters for M≡SnR Bonding in Filippou's Stannylidyne Complexes of Molybdenum and Tungsten

(119)Sn Mössbauer isomer shift (IS) and quadrupole splitting (ΔEQ) for M≡SnR bonding in metal-stannylidyne complexes trans-[Cl(PMe3)4Mo≡Sn-R] (1), trans-[Cl(PMe3)4W≡Sn-R] (2), trans-[Cl(dppe)2Mo≡Sn-R] (3), trans-[Cl(dppe)2W≡Sn-R] (4), [(dppe)2Mo≡Sn-R](+) (5), [(dppe)2W≡Sn-R](+) (6) (R = C6H3-2,6-Mes2) have been investigated for the first time. Calculations of optimized structures and (119)Sn Mössbauer parameters were carried out at the DFT/TPSS-D3(BJ)/TZVPP/ZORA level of theory. The calculated geometry parameters of stannylidyne complexes of molybdenum and tungsten (1-6) are in good agreement with experimental values of W-Sn and Sn-C bond distances. The calculated values of the isomer shift for the complexes (1-6) are almost same to the experimental values (within ±0.1 mm/s). Experimental values (ISexptl, 2.38-2.50 mm/s) and calculated values (IScalcd, 2.37-2.49 mm/s) of isomer shifts indicate that the oxidation state of tin in the studied complexes with M≡Sn-R bonding is Sn(II). The variations of ISexptl, as a function of Sn s electrons (Ns(Sn)), also exhibit a linear trend. (IS = 0.477Ns(Sn) - 1.888, R(2) = 0.9973). Calculated values of isomer shift (IScalcd) using the linear regression with the Ns(Sn) electron density are in excellent concord with the ISexptl.The calculated values of nuclear quadrupole splitting parameters (ΔEQ(calcd)) of (119)Sn using the relation ΔEQ(calcd) = (0.540 + 0.28) V are in agreement with the experimental values.

Assessment of density functionals and paucity of non-covalent interactions in aminoylyne complexes of molybdenum and tungsten [(η5-C5H5)(CO)2MEN(SiMe3)(R)] (E = Si, Ge, Sn, Pb): a dispersion-corrected DFT study

Geometries, bonding analysis and dispersion interactions in aminoylyne complexes of molybdenum and tungsten have been investigated using different density functionals.