Molecular Ln(III)-H-E(II) Linkages (Ln=Y, Lu; E=Ge, Sn, Pb).

Following the alkane-elimination route, the reaction between tetravalent aryl tintrihydride Ar*SnH3 and trivalent rare-earth-metallocene alkyls [Cp*2 Ln(CH{SiMe3 }2 )] gave complexes [Cp*2 Ln(µ-H)2 SnAr*] implementing a low-valent tin hydride (Ln=Y, Lu; Ar*=2,6-Trip2 C6 H3 , Trip=2,4,6-triisopropylphenyl). The homologous complexes of germanium and lead, [Cp*2 Ln(µ-H)2 EAr*] (E = Ge, Pb), were accessed via addition of low-valent [(Ar*EH)2 ] to the rare-earth-metal hydrides [(Cp*2 LnH)2 ]. The lead compounds [Cp*2 Ln(µ-H)2 PbAr*] exhibit H/D exchange in reactions with deuterated solvents or dihydrogen.

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 [Ar*Sn(C6H6)][Al(OC{CF3}3)4] (1a) the hydridostannylene complex [Cp2TaH2-Sn(H)Ar*][Al(OC{CF3}3)4] (2) was synthesized. Hydride bridged adducts [Cp2WH2EAr*][Al(OC{CF3}3)4] (E = Sn 3a, Pb 3b) were isolated as products of the reaction between Cp2WH2 and cations [Ar*E(C6H6)][Al(OC{CF3}3)4] (E = Sn 1a, Pb 1b). The tin adduct 3a exhibits a proton migration to give the hydridostannylene complex [Cp2W(H)[double bond, length as m-dash]Sn(H)Ar*][Al(OC{CF3}3)4] 4a. The cationic complex 4a is deprotonated at the tin atom in reaction with base MeNHC at 80 °C to give a hydrido-tungstenostannylene [Cp2W(H)SnAr*] 5a. Reprotonation of metallostannylene 5a with acid [H(Et2O)2][BArF] provides an alternative route to hydridotetrylene coordination. Complex 4a adds hydride to give the dihydrostannyl complex [Cp2W(H)-SnH2Ar*] (7). With styrene 4a shows formation of a hydrostannylation product [Cp2W(H)[double bond, length as m-dash]Sn(CH2CH2Ph)Ar*][Al(OC{CF3}3)4] (8). The lead adduct 3b was deprotonated with MeNHC to give plumbylene 5b [Cp2W(H)PbAr*]. Protonation of 5b with [H(Et2O)2][Al(OC{CF3}3)4] at -40 °C followed by low temperature NMR spectroscopy indicates a hydridoplumbylene intermediate [Cp2W(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 [Cp2W(H)Li]4 with organotetrylene halides. The metallogermylene [Cp2W(H)GeAr*] (5c) shows an isomerization via 1,2-H-migration to give the hydridogermylene [Cp2W[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 [Cp2ZrH2]2 reacts with tin cation 1a to give the trinuclear hydridostannylene adduct 10 [({Cp2Zr}2{µ-H})(µ-H)2µ-Sn(H)Ar*][Al(OC{CF3}3)4]. Deprotonation of 10 was carried out using benzyl potassium to give neutral [({Cp2Zr}2{µ-H})(µ-H)µ-Sn(H)Ar*] (11). 11 was also obtained from the reaction of low valent tin hydride [Ar*SnH]2 with two equivalents of [Cp2ZrH2]2. The trihydride Ar*SnH3 reacts with half of an equivalent of [Cp2ZrH2]2 under evolution of hydrogen and formation of a dihydrostannyl complex 13 [Cp2Zr(µ-H)SnH2Ar*]2 and with further equivalents of Ar*SnH3 to give bis(hydridostannylene) complex [Cp2Zr{Sn(H)Ar*}2].

Low valent lead and tin hydrides in reactions with heteroallenes.

Low valent organoelement hydrides of tin and lead, [(Ar*SnH)2] and [(Ar*PbH)2], were reacted with diorganocarbodiimide and adamantylisocyanate to give products of hydroelementation reactions. Carbon dioxide also reacts with both low valent hydrides, but a reaction product was only characterized in the tin hydride case. A hydride was transferred to the carbon atom and the formed formate anion [HCO2]- shows coordination at two tin atoms. Carbon disulfide reacts with the stannyl-stannylene isomer of the low valent organotin hydride. The stannyl part forms a Sn-C bond whereas the stannylene moiety coordinates at the two sulfur atoms. The dimeric organolead hydride exhibits transfer of both hydride ligands to the carbon atom of CS2 to give a dithiol ligand [CH2S2]2- bridging both organolead units.

Synthesis and Hydrogenation of Heavy Homologues of Rhodium Carbynes: [(Me3 P)2 (Ph3 P)Rh≡E-Ar*] (E=Sn, Pb).

Tetrylidynes [(Me3 P)2 (Ph3 P)Rh≡SnAr*] (10) and [(Me3 P)2 (Ph3 P)Rh≡PbAr*] (11) are accessed for the first time via dehydrogenation of dihydrides [(Ph3 P)2 RhH2 SnAr*] (3) and [(Ph3 P)2 RhH2 PbAr*] (7) (Ar*=2,6-Trip2 C6 H3 , Trip=2,4,6-triisopropylphenyl), respectively. Tin dihydride 3 was either synthesized in reaction of the dihydridostannate [Ar*SnH2 ]- with [(Ph3 P)3 RhCl] or via reaction between hydrides [(Ph3 P)3 RhH] and 1 / 2 [(Ar*SnH)2 ]. Homologous lead hydride [(Ph3 P)2 RhH2 PbAr*] (7) was synthesized analogously from [(Ph3 P)3 RhH] and 1 / 2 [(Ar*PbH)2 ]. Abstraction of hydrogen from 3 and 7 supported by styrene and trimethylphosphine addition yields tetrylidynes 10 and 11. Stannylidyne 10 was also characterized by 119 Sn Mössbauer spectroscopy. Hydrogenation of the triple bonds at room temperature with excess H2 gives the cis-dihydride [(Me3 P)2 (Ph3 P)RhH2 PbAr*] (12) and the tetrahydride [(Me3 P)2 (Ph3 P)RhH2 SnH2 Ar*] (14). Complex 14 eliminates spontaneously one equivalent of hydrogen at room temperature to give the dihydride [(Me3 P)2 (Ph3 P)RhH2 SnAr*] (13). Hydrogen addition and elimination at stannylene tin between complexes 13 and 14 is a reversible reaction at room temperature.

Hydridoorganostannylene Coordination: Group 4 Metallocene Dichloride Reduction in Reaction with Organodihydridostannate Anions.

Organodihydridoelement anions of germanium and tin were reacted with metallocene dichlorides of Group 4 metals Ti, Zr and Hf. The germate anion [Ar*GeH2 ]- reacts with hafnocene dichloride under formation of the substitution product [Cp2 Hf(GeH2 Ar*)2 ]. Reaction of the organodihydridostannate with metallocene dichlorides affords the reduction products [Cp2 M(SnHAr*)2 ] (M=Ti, Zr, Hf). Abstraction of a hydride substituent from the titanium bis(hydridoorganostannylene) complex results in formation of cation [Cp2 M(SnAr*)(SnHAr*)]+ exhibiting a short Ti-Sn interaction. (Ar*=2,6-Trip2 C6 H3 , Trip=2,4,6-triisopropylphenyl).

Deprotonation of Organogermanium and Organotin Trihydrides.

Terphenyltin and terphenylgermanium trihydrides were deprotonated in reaction with strong bases, such as LiMe, LDA, or KBn. In the solid state, the Li salts of the germate anion 4 and 4a exhibit a Li-Ge contact. In the Li salt of the dihydridostannate anion 6a, the Li cation is not coordinated at the tin atom instead an interaction of the Li cation with the hydride substituents was found. Evidenced by 1H-7Li-HOESY NMR spectroscopy the Li-salt of the deprotonated tin hydride 6a exhibits in toluene solution a contact between Li cation and hydride substituents, whereas in the 1H-7Li-HOESY NMR spectrum of the homologous germate salt 4a, no crosspeak between hydride and Li signals was found. The organodihydridogermate and -stannate react as nucleophiles with low-valent Group 14 electrophiles. Thus, three compounds were synthesized: Ar-Ë'-EH2-Ar (E', E = Sn, Ge; Pb, Ge; Pb, Sn; Ar = Ar', Ar*). Following an alternative synthesis Ar'SnH2PbAr* was synthesized in reaction between [(Ar*PbH)2] and [(Ar'SnH)4] generated in situ. In reaction between low-valent organotin hydride [(Ar*SnH)2] and organdihydridostannate [Ar*SnH2]- formation of distannate [Ar*2Sn2H3]- was found.