Insertion vs Ligand Exchange: Reactivity of DistannaAnsaHalf-Sandwich Complexes of Molybdenum and Tungsten toward Isocyanide and Phosphine Complexes of Nickel and Palladium

Abstract

Addition of [Ni(CNtBu) 4 ] or [Ni(PEt 3 ) 4 ] to the molybdenum and tungsten distanna ansa half-sandwich complexes [{κ 1 -SntBu 2 SntBu 2 (η 5 -C 5 H 4 )}M(CO) 3 ] (M = Mo, W) leads to carbonyl-isocyanide and carbonyl-phosphine exchange, respectively, resulting in enhanced reactivity toward chalcogen insertion in the case of the isocyanide compounds 8 and 9. Additionally, the first examples of oxidative addition of a half-sandwich ansa bridge toward zerovalent transition metals are presented by preparing the novel 1,3-distanna-2-pallada ansa half-sandwich complexes 17-20 by addition of [Pd(CNtBu) 2 ].

Iron ansa half sandwich complexes bearing a bridging distannadiyl moiety

“…Another interesting reactivity pattern is the oxidative addition of the tinetin bond to a low-valent group 10 metal atom [34,40,41].…”

“…Synthesis of the first ansa half sandwich complex. molybdenum as central metal atoms [32,34]. These compounds exhibit a high ring strain within the bridging moiety which gives rise to several insertion reactions into the tinetin bond.…”

Reaction betweentBuMgCl and SnCl4, Illustrating the Solvent-Dependent Predominant Formation of Cl(tBu2Sn)nCl (THF,n= 1; Toluene,n= 2; Hexane,n= 3) and the Subsequent Wavelength-Selective Photochemical Transformation ofn= 3 → 2 → 1

“…The Sn–Sn distance of 2.8681(6) Å is slightly longer than the Sn–Sn distance of 2.829(1) Å observed in 2 but significantly shorter than the Sn–Sn bond distance of 2.966(3)Å in octa- tert -butyltristannane, t Bu 3 Sn–Sn t Bu 2 –Sn t Bu 3 , due to the substitution of two t Bu groups by chlorine atoms . Overall the Sn–Sn bond distance is longer than the literature median value of 2.805 Å, ,, and the Sn–Cl bond distance of 2.4005(8)Å is also slightly longer than Sn–Cl distance of 2.393(1) Å observed in 2 . The two chlorine atoms are oriented in a gauche conformation with a torsion angle of 107°.…”

StrainedansaHalf-Sandwich Complexes of Ruthenium and Osmium and a Non-Iron Metallopolymer by Ring-Opening Polymerization

“…In contrast to these precursors, ansa half-sandwich complexes, which have likewise been found to form organometallic polymers by ring-opening reactions, are far less developed. While initial studies of ansa half-sandwich complexes were limited to carbon-bridged species, more recent work established a series of complexes featuring metals from groups 6, 8, and 10 bridged by silicon and tin moieties. − Given the potential of these heavier carbon congeners to facilitate the ROP of ansa sandwich complexes, it is surprising that the only known examples of organometallic polymers composed of half-sandwich repeating units feature iron as the central transition metal. The iron-containing precursors to these materials, reported by Pannell et al, featured both carbon–silicon and silicon–silicon bridges that readily underwent ROP at ambient temperature, yielding polymers with molecular weights up to 175000. ,, Herein we report the synthesis of the first non-iron ansa half-sandwich complex that provides a metallopolymer upon thermally-induced ROP.…”