Synthesis and characterization of aluminum(III) and tin(II) complexes supported by diiminophosphinate ligands and their application in ring-opening polymerization catalysis of ɛ-caprolactone

Synthesis and structures of homoleptic germylenes and stannylenes with sulfonimidamide ligands

An unusual series of germylenes and stannylenes with homoleptic symmetric and unsymmetric N-substituted sulfonimidamide ligands PhSO(NiPr)(NHiPr) 1 and PhSO(NMes)(NHiPr) 2 have been prepared by protonolysis reaction of Lappert's metallylenes [M(HMDS)₂] (M = Ge or Sn) with two equivalents of the appropriate sulfonimidamide. The homoleptic germylenes [PhSO(NiPr)₂]₂Ge 3 and [PhSO(NMes)(NiPr)]₂Ge 4, and stannylenes [PhSO(NiPr)₂]₂Sn 5 and [PhSO(NMes)(NiPr)]₂Sn 6 were fully characterized by NMR spectroscopy and by X-ray diffraction analysis. DFT calculations have been performed to understand the electronic properties brought by the sulfonimidamide ligand.

Hydroboration of carbonyls and imines by an iminophosphonamido tin(II) precatalyst

A novel three-coordinated tin(II) chloride [Ph₂P(N^tBu)₂]SnCl (1) supported by an N,N'-di-tert-butyliminophosphonamide having two phenyl groups on the phosphorus atom was synthesized by the reaction of the starting lithium iminophosphonamide [Ph₂P(N^tBu)₂]Li with SnCl₂·(dioxane) in toluene. The molecular structure of 1 was established by X-ray diffraction analysis. Tin(II) chloride 1 can act as an efficient precatalyst for the hydroboration of a wide variety of aldehydes, ketones, and imines at -10 °C. DFT calculations propose that hydroboration involves hydride transfer from the corresponding tin(II) hydride intermediate [Ph₂P(N^tBu)₂]SnH (10) to the carbonyl substrates via four-membered transition states (TS-12), affording three-coordinated tin(II) alkoxide intermediates [Ph₂P(N^tBu)₂]SnOR (13), followed by the stepwise reaction of 13 with HBpin (pin = pinacolate) to release the boronate esters and regenerate the tin(II) hydride 10. The stoichiometric reaction of the in site-generated 10 with benzophenone 2a at -10 °C led to the formation of 13. Moreover, 13 also stoichiometrically reacted with HBpin at -10 °C, forming the corresponding boronate ester 3a and 10 based on the ¹H NMR spectrum of the reaction mixture.

Synthesis of Aluminum Complexes Bearing 8-Anilide-5,6,7-trihydroquinoline Ligands: Highly Active Catalyst Precursors for Ring-Opening Polymerization of Cyclic Esters

The stoichiometric reactions of 8-(2,6-R¹-4-R²-anilide)-5,6,7-trihydroquinoline (LH) with AlR₃ (R = Me or Et) afforded the aluminum complexes LAlR₂ (Al1⁻Al5,Al1: R¹ = ⁱPr, R² = H, R = Me; Al2: R¹ = Me, R² = H, R = Me; Al3: R¹ = H, R² = H, R = Me; Al4: R¹ = Me, R² = Me, R = Me; Al5: R¹ = Me, R² = Me, R = Et) in high yields. All aluminum complexes were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Al4 and Al5 were determined by single-crystal X-ray diffractions and revealed a distorted tetrahedral geometry at aluminum. In the presence of BnOH, complexes Al1⁻Al5 efficiently initiated the ring-opening homopolymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA), respectively, in a living/controlled manner.

Synthesis and reactivity of a germylene stabilized by a boraguanidinate ligand

The reactivity of a germylene stabilized by a boraguanidinate ligand with various reagents is reported.

Germylenes and stannylenes stabilized within N2PE rings (E = Ge or Sn): combined experimental and theoretical study

Bis(amino)phosphanes were shown to be excellent easily accessible precursors for the preparation of a variety of tetrylenes that significantly differ in their structures.

Reactivity of bis(organoamino)phosphanes with magnesium(ii) compounds

The reactivity of bis(organoamino)phosphanes with magnesium(ii) reagents is reported. The outcome of the reactions is influenced by a tautomeric H-shift in ligand backbones.

Understanding the directed ortho lithiation of (R)-Ph2P(NCO2Me)NHCH(Me)Ph. NMR spectroscopic and computational study of the structure of the N-lithiated species

The multinuclear magnetic resonance and computational study of the structure of N-lithium (R)-Ph₂P(NCO₂Me)NHCH(Me)Ph revealed the origin of its diastereoselective ortho lithiation.

N- versus P-coordination in bis(amino)cyclodiphosph(III)azane complexes of aluminum

The reaction of the bis(amino)cyclodiphosph(III)azane, cis-{(tBuNH)(2)(PNtBu)(2)}, with AlMe(3), AlClMe(2), AlCl(2)Me, and AlCl(3) is reported. The less Lewis acidic compound AlMe(3) forms the adduct cis-[(tBuNH)(2)(PNtBu){P.(AlMe(3))NtBu}] (1), in which the aluminum atom is exclusively coordinated to one phosphorus atom. At elevated temperatures AlMe(3) undergoes migratory exchange between the two phosphorus atoms, but no methane elimination is observed. By using the more Lewis acidic compound AlClMe(2) the P-coordinated compound cis-[(tBuNH)(2)(PNtBu){P(AlClMe(2))NtBu}] (2) can be obtained at low temperatures. Compound 2 rearranges irreversibly to a product in which the AlClMe(2) group is coordinated by one exo-cyclic nitrogen atom. A concomitant 1,2-H shift from this nitrogen atom onto the phosphorus atom is observed. The N-coordinated rearrangement product slowly decomposes via a P-N bond cleavage in solution. Reaction of the even more Lewis acidic compounds AlCl(2)Me and AlCl(3) finally led to stable adducts, cis-[(tBuNH)(PNtBu)(tBuNAlCl(2)Me){P(H)NtBu}] (3), and cis-[(tBuNH)(PNtBu)(tBuNAlCl(3)){P(H)NtBu}] (4), in which the aluminum atoms are N-coordinated by a tBuN=PH unit.