Heavy metalla vinyl-cations show metal-Lewis acid cooperativity in reaction with small molecules (NH 3 , N 2 H 4 , H 2 O, H 2 ).

Halide abstraction from tetrylidene complexes [TbbE(Br)IrH(PMe 3 ) 3 ] [E = Ge (1), Sn (2)] and [Ar*E(Cl)IrH(PMe 3 ) 3 ] gives the salts [TbbEIrH(PMe 3 ) 3 ][BAr F 4 ] [E = Ge (3), Sn (4)] and [Ar*EIrH(PMe 3 ) 3 ][BAr F 4 ] [E = Ge (3'), E = Sn (4')] (Tbb = 2,6-[CH(SiMe 3 ) 2 ] 2 -4-( t -Bu)C 6 H 2 , Ar* = 2,6-Trip 2 C 6 H 3 , Trip = 2,4,6-triisopropylphenyl). Bonding analysis suggests their most suitable description as metalla-tetrela vinyl cations with an Ir[double bond, length as m-dash]E double bond and a near linear coordination at the Ge/Sn atoms. Cationic complexes 3 and 4 oxidatively add NH 3 , N 2 H 4 , H 2 O, HCl, and H 2 selectively to give: [TbbGe(NH 2 )IrH 2 (PMe 3 ) 3 ][BAr F 4 ] (5), [TbbE(NHNH 2 )IrH 2 (PMe 3 ) 3 ][BAr F 4 ] [E = Ge (7), Sn (8)], [TbbE(OH)IrH 2 (PMe 3 ) 3 ][BAr F 4 ] [E = Ge (9), Sn (10)], [TbbE(Cl)IrH 2 (PMe 3 ) 3 ][BAr F 4 ] [E = Ge (11a), Sn (12a)], [TbbGe(H)IrH 2 (PMe 3 ) 3 ][BAr F 4 ] (13), [TbbSn(μ-H 3 )Ir(PMe 3 ) 3 ][BAr F 4 ] (14), and [TbbSn(H)IrH 2 (PMe 3 ) 3 ][BAr F 4 ] (15). 14 isomerizes to give 15 via an 1,2-H shift reaction. Hydride addition to cation 3 gives a mixture of products [TbbGeHIrH(PMe 3 ) 3 ] (16) and [TbbGeIrH 2 (PMe 3 ) 3 ] (17) and a reversible 1,2-H shift between 16 and 17 was studied. In the tin case 4 the dihydride [TbbSnIrH 2 (PMe 3 ) 3 ] (18) was isolated exclusively. The PMe 3 and PEt 3 derivatives, 18 and [TbbSnIrH 2 (PEt 3 ) 3 ] (19), respectively, could also be synthesized in reaction of [TbbSnH 2 ] - with the respective chloride [(R 3 P) n IrCl] (R = Me, n = 4; R = Et, n = 3). Reaction of complex 19 with CO gives the substitution product [TbbSnIrH 2 (CO)(PEt 3 ) 2 ] (20). Further reaction with CO results in hydrogen transfer from the iridium to the tin atom to give [TbbSnH 2 Ir(CO) 2 (PEt 3 ) 2 ] (21). The reversibility of this ligand induced reductive elimination transferring 20 to 21 is shown.