Syntheses and Structures of Zinc Bis(phosphinimino)methanide Complexes

Reactions of bis(phosphinimino)methanes H₂C(PPh₂NR)₂ [R = SiMe₃ (L¹H), Ph (L²H), 2,6‐iPr₂‐C₆H₃ (DIPP) (L³H)] with ZnR₂ (R = Me, Et) yielded the corresponding bis(phosphinimino)methanide zinc complexes LZnMe [L² ( 1 ), L³ ( 2 )] and LZnEt [L¹ ( 3 ), L² ( 4 ), and L³ ( 5 )]. Complexes 1 – 5 were characterized by heteronuclear NMR (¹H, ¹³C, ³¹P) and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction.     

A bis(phosphinimino)methanide lanthanum amide as catalyst for the hydroamination/cyclisation, hydrosilylation and sequential hydroamination/hydrosilylation catalysis

[La[N(SiHMe2)2]2[CH(PPh2NSiMe3)2]], which was obtained via an amine elimination starting from [CH2(PPh2NSiMe3)2] and [La[N(SiHMe2)2]3(THF)2], was used as catalyst for the hydroamination/cyclisation, the hydrosilylation and the sequential hydroamination/hydrosilylation reaction.     

Reactions of (2,3-dimethylenetetramethylene)bis(dipropylborane) with carbonyl compounds

(2,3-Dimethylenetetramethylene)bis(dipropylborane) (1) prepared by borylation of 2,3-dimethylbutadienediyl dipotassium reacts with ketones to form symmetrical diols in a yield of 46–73%. [4+2]-Cycloaddition reactions of diborane1 with 1,2-dicarbonyl compounds proceed highly stereospecifically, affording onlycis-isomers of 4,5-dimethylenecyclohexane1, 2-diols.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 155–159, January, 1993.     

Group 1 and 13 complexes of aryl-substituted bis(phosphinimino)methyls

The organolithium reagent [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] was easily obtained by deprotonation of H₂C(Ph₂PNC₆H₂Me₃-2,4,6)₂ with nBuLi in diethyl ether solution. The crystal structure of [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] has been determined and shown to consist a monomeric chelate structure that contains a distorted, trigonal planar lithium centre. The ligand precursor has also been deprotonated with both Me₃Al and Me₂AlCl to yield the tetrahedral organoaluminium complexes, [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}AlMe₂] and [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Al(Cl)Me]. Reaction of [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] with either AlX₃ (X=Cl, Br, I) or GaCl₃ yielded a series of dihalo derivatives [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}MX₂] all of which have been shown to exist as similar monomeric species containing four-coordinate group 13 centres.     

Three-coordinate bis(phosphinimino)methanide derivatives of ‘open shell’ [M(II)] (M = Mn, Fe, Co) transition metals

An alternative two-step synthesis of the previously reported bis(diphenylphosphinimino)methane [CH₂(Ph₂P = NC₆H₃ⁱPr₂-2,6)₂] involving bromine oxidation of dppm and metathesis with 2,6-diisopropylaniline is described. [CH₂(Ph₂PNC₆H₃ⁱPr₂-2,6)₂] is readily deprotonated by the transition metal silylamides [M{N(SiMe₃)₂}₂] (M = Mn, Fe and Co) to provide a series of exclusively three-coordinate derivatives [{CH(Ph₂PNC₆H₃ⁱPr₂-2,6)₂M{N(SiMe₃)₂}] which have been characterised by elemental analysis, magnetic measurements and, in the case of the Fe derivative, X-ray structural analysis. Reactivity studies have shown that even such sterically demanding bis(phosphinimino)methanide ligands are prone to protonolysis and reductive [P(V) to P(III)] degradation which limits their utility as stable platforms for further M(II) derivitisation.     

Reactions of hypersilyl potassium with rare-earth metal bis(trimethylsilylamides): addition versus peripheral deprotonation

The scope of hypersilyl potassium, KHyp [Hyp = Si(SiMe3)3], as a silylation or deprotonation agent for some rare-earth bis(trimethylsilyl)amides has been explored. Thus, the reaction with Yb{N(SiMe3)2}2 affords the addition product [K][YbHyp{N(SiMe3)2}2] (2) in high yield, which contains a three-coordinate ytterbium atom, therefore representing the first example of a lanthanide silyl with a coordination number lower than 6. In contrast, deprotonation on the periphery is observed with the tris(amides) Ln{N(SiMe3)2}3 (Ln = Y, Yb) and compounds of the type [K][CH2Si(Me)2N(SiMe3)Ln{N(SiMe3)2}2] (Ln = Y (3), Yb (4)) are isolated. Crystallization of 3 from a mixture of benzene and heptane afforded the bis(benzene) solvate [(C6H6)2K][CH2Si(Me)2N(SiMe3)Y{N(SiMe3)2}2] (3a). The reaction between the strong bases nBuLi/tetramethylenediamine (TMEDA) or tBuLi with Y{N(SiMe3)2}3 or Yb{N(SiMe3)2}3 yielded the deprotonation product [(tmeda)Li][CH2Si(Me)2N(SiMe3)Y{N(SiMe3)2}2] (6) and the reduction product [LiYb{N(SiMe3)2}3] (7), respectively. Instead of the expected bimetallic product, the reaction between YbI(2) and 2 equiv of 3 gave the neutral complex [Y{CH2Si(Me)2N(SiMe3)}{N(SiMe3)2}(thf)] (8) in good yield. The compounds have been characterized by melting point, elemental analysis, IR spectroscopy, and X-ray crystallography and for selected species by 1H, 13C, 29Si, and 171Yb NMR spectroscopy. For 3a and 4, the nature of the bonding between the carbanionic centers and the lanthanide and potassium cations was studied by density functional theory calculations.     

Reactions of organomagnesium compounds with potassium and triethyloxonium fluoborates

Russian Chemical Bulletin -     

Multifunctional behavior by a Bis-(phosphinimino)methanide ligand: eta 2- vs eta 3-coordination vs Bronsted basicity

The reaction of [(Cymene)RuCl2]2 with the chelate LiHC(PPh2NPh)2 occurs to remove both chloride ligands, to furnish a cationic Ru(II) complex with the monoanionic ligand bound eta3, through two N and an sp3 carbon. This cation is also produced from the conjugate acid of the ligand H2C(PPh2NPh)2 because this molecule can serve as a Br?nsted base, to deprotonate the acidic carbon of another molecule of H2C(PPh2NPh)2. DFT calculations show an energy surface where (Cymene)RuHC(PPh2NPh)2L is more stable with a Ru-CH(PPh2NPh)2 bond and with L = Cl- or MeCN not coordinated to Ru, than to an eta2-HC(PPh2NPh)2 structure with coordinated L; this is tested experimentally. The greater tendency for this ligand to be coordinated eta3 vs analogous diketiminates is discussed. The nucleophilicity of Cgamma in structure 1, vs that of donors L = Cl- or MeCN, is evaluated to understand the preference of the bis(phosphinimino)methanide to be bidentate or tridentate.     

Reactions of bis(α-hydroxyalkyl)phosphines with iminoboranes

Conclusions Bis(-hydroxyalkyl)phosphines react with iminoboranes as either proton donors or cryptoaldehydes depending on the substituents at the carbon atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2409–2411, October, 1988.     

Reactions of bis(2,4-dinitrophenyl) phosphate with hydroxylamine

For dephosphorylation of bis(2,4-dinitrophenyl) phosphate (BDNPP) by hydroxylamine in water, pH region 4-12, the observed first-order rate constant, k(obs), initially increases as a function of pH, but is pH-independent between pH 7.2 and pH 10. The initial BDNPP cleavage by nonionic NH(2)OH (<0.2 M) involves attack by the OH group and follows first-order kinetics, but the overall initial reaction of BDNPP liberates ca. 1.7 mol of 2,4-dinitrophenoxide ion (DNP). This initial reaction generates a short-lived O-phosphorylated hydroxylamine, 2, followed by three possible reactions: (1) reaction of 2 with hydroxylamine, generating 2,4-dinitrophenyl phosphate (DNPP, 3), which subsequently forms DNP; (2) intramolecular displacement of the second DNP group and rapid decomposition of the cyclic intermediate to form phosphonohydroxylamine and eventually inorganic phosphate; (3) a novel rearrangement with intramolecular aromatic nucleophilic substitution involving a cyclic intermediate and migration of the 2,4-dinitrophenyl group from O to N. Values of k(obs) increase modestly with pH > 10, the reaction is biphasic, and the yield of DNP increases. An increase in [NH(2)OH] also increases the yield of DNP, due largely to accelerated hydrolysis of DNPP.     

Reactions of coordinated mercaptide group—III. Reactions of acyl chlorides on bis(thiosemicarbazonato) chelates of nickel(II)

Reactions of acetyl chloride and benzoyl chloride have been carried out on bis(thiosemicarbazonato)nickel(II) complexes of acetone and ethylmethyl keto