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 [H2bzamP]Cl and GeCl2(dioxane) or SnCl2 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{κ3E,N,P-ECl(bzamP)2}(cod)] (E = Ge (3a) and Sn (3b); cod = η4-1,5-cyclooctadiene) and the E(bzamP)2 ligand of [Ni{κ4E,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.

Phosphane-functionalized heavier tetrylenes: synthesis of silylene- and germylene-decorated phosphanes and their reactions with Group 10 metal complexes

The stable phosphane-functionalized heavier tetrylenes E(tBu2bzam)pyrmPtBu2 (E = Si (1Si), Ge (1Ge); tBu2bzam = N,N'-ditertbutylbenzamidinate; HpyrmPtBu2 = ditertbutyl(2-pyrrolylmethyl)phosphane) have been prepared by reacting the amidinatotetrylenes E(tBu2bzam)Cl (E = Si, Ge) with LipyrmPtBu2. The reactions of 1Si and 1Ge with selected M0 and MII (M = Ni, Pd, Pt) metal precursors have allowed the synthesis of square-planar [MCl2{κ2E,P-E(tBu2bzam)pyrmPtBu2}] (M = Ni, Pd, Pt; E = Si, Ge), tetrahedral [Ni{κ2E,P-E(tBu2bzam)pyrmPtBu2}(cod)] (E = Si, Ge; cod = 1,5-cyclooctadiene) and triangular [M{κ2E,P-E(tBu2bzam)pyrmPtBu2}(PPh3)] (M = Pd, Pt; E = Si, Ge) complexes, showing that 1Si and 1Ge are excellent Si,P- and Ge,P-chelating ligands that, due to their large steric bulk, are able to stabilize three-coordinate Pd0 and Pt0 complexes.

Mechanism of generation of closo-decaborato amidrazones. Intramolecular non-covalent B–H⋯π(Ph) interaction determines stabilization of the configuration around the amidrazone CN bond

Three types of N(H)-nucleophiles were used to study the nucleophilic addition to the CN group of the 2-propanenitrilium closo-decaborate cluster giving N-closo-decaborato amidrazones.