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.


Materials
Solvents were dried over appropriate desiccating reagents and were distilled under argon before use.Compounds 2-(diphenylphosphanyl)ethylamine S1 and Nisopropylbenzimidoyl chloride S2 were prepared following published procedures and were stored under argon in the drybox.All remaining reagents were purchased from commercial sources.All reagents were stored under argon in a drybox.All reaction products were vacuum-dried for several hours prior to being weighted and analyzed.

Instrumentation and Measurements
All reactions and product manipulations were carried out under argon in an MBraun UNIlab Pro drybox or using Schlenk-vacuum line techniques.Unless otherwise stated, the reactions were carried out at room temperature.Mechanochemical reactions were performed with a Retsch MM400 ball mill using stainless steel (440B type) grinding jars with stainless steel ball bearings, carrying out all reagent and product manipulations in the drybox and sealing the grinding jars with Teflon tape prior to their transfer to the ball mill.NMR spectra were run on Bruker NAV-400, AV-400, and DPX-300 instruments, using as standards the residual protic solvent resonance for for 119 Sn (d 0.0 ppm).Microanalyses were obtained with a Thermo-Finnigan FlashEA112 microanalyzer.High-resolution mass spectra (HRMS) were obtained with a Bruker Impact II mass spectrometer operating in the ESI-Q-TOF positive mode; data given refer to the most abundant isotopomer of the observed species with the greatest mass.CHN microanalyses were not obtained for 1, 3a and 3b since, according to their NMR data, they were affected by minor unknown impurities (for 1) or variable amounts of n-hexane (for 3a and 3b), that could not be removed.with hexane (30 mL) to give 1 (almost pure, see Figure S1) as a white solid (2.74 g, 99%). 31P{ 1 H} NMR (CDCl3, 121.5 MHz, 298 K; Figure S2): d -21.9 (s) ppm.
The filtrates were collected to give a yellow solution that was evaporated to dryness.The resulting white residue was washed with hexane (5×2 mL) and then with hexane/toluene (10:1, 5×2 mL) to give 1 as a white solid (407 mg, 56%
Empirical absorption corrections were applied using the SCALE3 ABSPACK algorithm as implemented in CrysAlisPro RED.S3 The structures were solved with SIR-97.S4 Isotropic and full matrix anisotropic least square refinements were carried out using SHELXL.S5 One isopropyl group (C75) of 2a was disordered over two positions with a 75:25 occupancy ratio, requiring restraints on its geometrical and thermal parameters.The toluene solvent molecule found in the asymmetric unit of 2b•(C7H8) was disordered over two positions with a 79:21 occupancy ratio, requiring restraints on its geometrical and thermal parameters.The solvent molecules found in the asymmetric unit of 3a•(C6H14), which were severely disordered, were modelled as two half hexane molecules with an equal occupancy ratio (each one disordered into two positions with an equal occupancy ratio) and required restraints on their geometrical and thermal parameters.The half ether solvent molecule found in the asymmetric unit of 3b•0.5(C4H10O) was disordered about a center of symmetry and required restraints on its geometrical and thermal parameters.The WINGX program system S6 was used throughout the structure determinations.The molecular plots were made with MERCURY.S7 Theoretical Calculations.The structure optimization of 4a was performed with the Gaussian09 suite of programs, S8 using the wB97XD functional, S9 which includes the second generation of Grimme's dispersion interaction correction.S10 The Stuttgart-Dresden relativistic effective core potentials and the associated basis sets (SDD) was used for the Ni, Ge and Sn atoms.S11 The basis set used for the remaining atoms was the cc-pVDZ.S12 Frequency calculations confirmed the optimized structure as energy minimum (zero imaginary eigenvalues).Gibbs energies were computed at 298.15 K and 1.0 atm.

[
H2bzamP]Cl (1): A solution of N-isopropylbenzimidoyl chloride (1.33 g, 7.30 mmol) in dichloromethane (4 mL) was cooled at -20 °C and dropwise added to a dichloromethane solution (4 mL) of 2-(diphenylphosphanyl)ethylamine (1.67 g, 7.30 mmol) previously cooled at -20 °C.The resulting pale-yellow solution was stirred for 1 h at room temperature.The solvent was then removed in vacuo and the solid residue was washed

Table S1 .
Crystal, measurement and refinement data for the compounds studied by X-ray diffraction.