Hydroalumination of R-P(H)-C[triple bond, length as m-dash]C-tBu with bulky H-Al[CH(SiMe3)2]2 afforded the new P-H functionalized Al/P-based frustrated Lewis pair R-P(H)-C[[double bond, length as m-dash]C(H)-tBu]-AlR2 [R = CH(SiMe3)2; FLP 7]. A weak adduct of 7 with benzonitrile (8) was detected by NMR spectroscopy, but could not be isolated. tert-Butyl isocyanide afforded a similar, but isolable adduct (9), in which the isocyanide C atom was coordinated to aluminium. The unique reactivity of 7 became evident from its reactions with the heteroatom substituted nitriles PhO-C[triple bond, length as m-dash]N, PhCH2S-C[triple bond, length as m-dash]N and H8C4N-C[triple bond, length as m-dash]N. Hydrophosphination of the C[triple bond, length as m-dash]N triple bonds afforded imines at room temperature which were coordinated to the FLP by Al-N and P-C bonds to yield AlCPCN heterocycles (10 to 12). These processes depend on substrate activation by the FLP. Diphenylcyclopropenone and its sulphur derivative reacted with 7 by addition of the P-H bond to a C-C bond of the strained C3 ring and ring opening to afford the fragment (Z)-Ph-C(H)[double bond, length as m-dash]C(Ph)-C-X-Al (X = O, S). The C-O or C-S groups were coordinated to the FLP to yield AlCPCX heterocycles (13 and 14). The thiocarbonyl derived compound 14 contains an internally stabilized phosphenium cation with a localized P[double bond, length as m-dash]C bond, a trigonal planar coordinated P atom and a short P[double bond, length as m-dash]C distance (168.9 pm). Insight into formation mechanisms, the structural and energetic properties of FLP 7 and compounds 13 and 14 was gained by quantum chemical DFT calculations.

The reaction of tBu2P(O)H with Bis2AlH (Bis=CH(SiMe3)2) afforded the adduct tBu2P(H)–O–Al(H)Bis2 (3). It slowly releases H2 to form the first oxygen-bridged geminal Al/P Frustrated Lewis Pair tBu2P–O–AlBis2. It is capable...

The P−H functionalized FLPs R(H)PC(AlBis 2 )C(H)-CMe 3 (1a, R = Bis; 1b, R = Mes; Bis = CH(SiMe 3 ) 2 ) combine the typical FLP properties based on Lewis acidic Al and basic P atoms with the reactivity of a P−H bond. They allow the coordination of substrates followed by hydrophosphination with the activated P−H group. Reactions of 1a with R′−NCS (R′ = Ph, CMe 3 ) or of both FLPs with Et−N CCPh 2 afforded five-membered AlCPCS/N heterocycles (4 and 5) via coordination of CS or CN bonds to the FLP backbone. Isomerization by a 1,3-H shift from P to N or C (6 and 7) was only achieved in the presence of an auxiliary base (DABCO; 1−5 mol %). (Z)-1a coordinated CO 2 to yield the adduct 8, which features a five-membered AlCPCO heterocycle with an exocyclic CO bond. Addition of bases such as DABCO and DBU afforded by deprotonation of the P atom the compounds [Bis-PC(AlBis 2 )C(H)−CMe 3 (CO 2 )] − [HB] + (9a, B = DABCO; 9b, B = DBU) that displayed hydrogen bonding between the ammonium ions and the exocyclic O atom of the FLP adducts in solution and the solid state. The stronger base n-BuLi afforded the dimeric Li compound 10, in which the Li cation was coordinated in a chelating manner to the oxygen atoms of one FLP adduct and additionally to the exocyclic O atom of the second adduct, resulting in a fourmembered Li 2 O 2 heterocycle. The related reaction of (Z)-1a with DABCO(SO 2 ) 2 led in contrast to the elimination of BisH and formation of a SO 2 -bridged dimer that features a central (AlOSO) 2 heterocycle with Al−O and S−O single bonds. The resulting unusual structural motifs may be derived from those of dialkylcarbamic or dialkylamidosulfinic acids with the N atoms replaced by P atoms.

Photo-dimers of 1,5-diethynylanthracene and 1,5-bis[(trimethylsilyl)ethynyl]anthracene, obtained by UV radiation of the monomers, were treated with the bulky aluminium hydride [(SiMe3)2HC]2AlH in hydroalumination reactions. Hydroalumination of the tetraethynyl-substituted anthracene photo-dimers (syn...

Substituted anthracene derivatives−monomers and photodimers−bearing alkynyl units were treated with the bulky aluminum hydride [(SiMe 3 ) 2 HC] 2 AlH in hydroalumination reactions in order to investigate the influence of the substituents on the spacing between the alkynyl units. While 1,8bis[(trimethylsilyl)ethynyl]anthracene only resulted in the mono-hydroalumination product, 1,8-diethynylanthracene and its photo-dimer afforded the products of twofold hydroalumination. In the case of 1,8-diethynylanthracene, the product underwent a cis/trans-isomerization of one of the newly formed C�C bonds. This process was examined via quantum-chemical calculations. The twofold hydroaluminated syn-photo-dimer of 1,8-diethynylanthracene was treated with various donor molecules to gain insights into its host−guest chemistry.