Synthesis and Some Coordination Chemistry of Phosphane-Difunctionalized Bis(amidinato)-Heavier Tetrylenes: A Previously Unknown Class of PEP Tetrylenes (E = Ge and Sn).

The bis(amidinato)-heavier tetrylenes E(bzamP) 2 (E = Ge ( 2a ) and Sn ( 2b ); bzamP = N -isopropyl- N '-(diphenylphosphanylethyl)benzamidinate), which are equipped with one heavier tetrylene (germylene or stannylene) and two phosphane fragments (one on each amidinate moiety) as coordinable groups, have been synthesized from the benzamidinum salt [H 2 bzamP]Cl and GeCl 2 (dioxane) or SnCl 2 in 2:1 mol ratio. A preliminary inspection of their coordination chemistry has shown that their amidinate group can also be involved in the bonding with the metal atoms as tridentate ENP and tetradentate PENP' coordination modes have been observed for the ECl(bzamP) 2 ligand of [Ir{κ 3 E , N , P -ECl(bzamP) 2 }(cod)] (E = Ge ( 3a ) and Sn ( 3b ); cod = η 4 -1,5-cyclooctadiene) and the E(bzamP) 2 ligand of [Ni{κ 4 E , N , P , P '-E(bzamP) 2 }] (E = Ge ( 4a ) and Sn ( 4b )), which are products of reactions of 2a and 2b with [IrCl(cod)] 2 (1:0.5 mol ratio) and [Ni(cod) 2 ] (1:1 mol ratio), respectively. These products contain a 5-membered NCNEM ring that results from the insertion of the metal M atom into an E-N bond of 2a and 2b . Additionally, while iridium(I) complexes 3a and 3b are chloridotetryl derivatives (insertion of the tetrylene E atom into the Ir-Cl bond has also occurred) that have an uncoordinated phosphane group, nickel(0) complexes 4a and 4b contain a tetrylene fragment that, maintaining the lone pair, behaves as a σ-acceptor ( Z -type) ligand.