Hydridotetrylene [Ar*EH] (E = Ge, Sn, Pb) coordination at tantalum, tungsten, and zirconium.

In a reaction of tantalocene trihydride with the low valent aryl tin cation [ArSn(CH)][Al(OC{CF})] (1a) the hydridostannylene complex [CpTaH-Sn(H)Ar][Al(OC{CF})] (2) was synthesized. Hydride bridged adducts [CpWHEAr*][Al(OC{CF})] (E = Sn 3a, Pb 3b) were isolated as products of the reaction between CpWH and cations [ArE(CH)][Al(OC{CF})] (E = Sn 1a, Pb 1b). The tin adduct 3a exhibits a proton migration to give the hydridostannylene complex [CpW(H)[double bond, length as m-dash]Sn(H)Ar][Al(OC{CF})] 4a. The cationic complex 4a is deprotonated at the tin atom in reaction with base NHC at 80 °C to give a hydrido-tungstenostannylene [CpW(H)SnAr*] 5a. Reprotonation of metallostannylene 5a with acid [H(EtO)][BAr] provides an alternative route to hydridotetrylene coordination. Complex 4a adds hydride to give the dihydrostannyl complex [CpW(H)-SnHAr*] (7). With styrene 4a shows formation of a hydrostannylation product [CpW(H)[double bond, length as m-dash]Sn(CHCHPh)Ar*][Al(OC{CF})] (8). The lead adduct 3b was deprotonated with NHC to give plumbylene 5b [CpW(H)PbAr*]. Protonation of 5b with [H(EtO)][Al(OC{CF})] at -40 °C followed by low temperature NMR spectroscopy indicates a hydridoplumbylene intermediate [CpW(H)[double bond, length as m-dash]Pb(H)Ar*] (4b). Hydrido-tungstenotetrylenes of elements Ge (5c), Sn (5a) and Pb (5b) were also synthesized reacting the salt [CpW(H)Li] with organotetrylene halides. The metallogermylene [CpW(H)GeAr*] (5c) shows an isomerization 1,2-H-migration to give the hydridogermylene [CpW[double bond, length as m-dash]Ge(H)Ar*] (9), which is accelerated by addition of AIBN. 9 is at rt photochemically transferred back to 5c under light of a mercury vapor lamp. Zirconocene dihydride [CpZrH] reacts with tin cation 1a to give the trinuclear hydridostannylene adduct 10 [({CpZr}{μ-H})(μ-H)μ-Sn(H)Ar*][Al(OC{CF})]. Deprotonation of 10 was carried out using benzyl potassium to give neutral [({CpZr}{μ-H})(μ-H)μ-Sn(H)Ar*] (11). 11 was also obtained from the reaction of low valent tin hydride [ArSnH] with two equivalents of [CpZrH]. The trihydride ArSnH reacts with half of an equivalent of [CpZrH] under evolution of hydrogen and formation of a dihydrostannyl complex 13 [CpZr(μ-H)SnHAr*] and with further equivalents of ArSnH to give bis(hydridostannylene) complex [CpZr{Sn(H)Ar}].