Search

The coordination chemistry of 1-phosphafulvenes was investigated by employing their [6 + 4] adducts or α-C2-bridged biphospholes as a precursor. Unbridged phosphacymantrenes arise from 1-phosphafulvenes via proton abstraction. α-C2-bridged biphosphacymantrenes are probably yielded by the reductive coupling of 1-phosphafulvene with Mn2(CO)10. The coordination behavior of 1-phosphafulvenes is comparable to that of pentafulvenes, which again demonstrates the phosphorus-carbon analogy in low-coordinate organophosphorus chemistry. [ABSTRACT FROM AUTHOR]

The stabilization of a phosphirane ring by complexation to tungsten pentacarbonyl allows the emergence of the Cloke-Wilson rearrangement in 1-acylphosphirane complexes around 130 °C. Contrary to the cyclopropane case, this transformation of the 1-acylphosphirane to the 1,3-oxaphosphol-3-ene complexes is reversible. It is favored by a 2-phenyl, and even a 2-vinyl substitution. The 1,3-oxaphosphol-3-ene complexes are trapped by conjugated dienes. [ABSTRACT FROM AUTHOR]

The heavier main group multiple bonds offer an effective tool for small molecule activation. Transient 2H‐phosphinidole working as a reactive phosphadiene system undergoes phospha‐Diels‐Alder reaction with a wide range of non‐activated aromatic carbocycles and heterocycles, including naphthalene, anthracene, phenanthrene, furan, thiophene, pyrrole, pyridine, and benzo‐fused heterocycles, affording concise access to a range of polycyclic fused rings feature with phosphorus at the bridgehead. These results demonstrate that non‐activated (hetero)arenes are capable of acting as 2π systems in [4+2] cycloaddition with highly reactive 2H‐phosphindole complex. [ABSTRACT FROM AUTHOR]

The reactions of BX3 (X = Cl, Br) with 7-R-7-phosphanorbornadiene-M(CO)5 (M = Mo, W) complexes ( 1) yields products 2 and 4 in which the RP-M(CO)5 unit is inserted into one of the carboxyl units of the phthalic derivative as a result of the collapse of the bridge. When X = Br, 4 cyclizes to give new six-membered heterocycles 5 with quasiplanar structures. When treated by an excess of BBr3, heterocycles 5 undergo ring contraction to afford five-membered oxocyclic products 6. [ABSTRACT FROM AUTHOR]

Transientterminal phosphinidene complexes [RP-W(CO)5] dimerize inthe presence of copper chloride, and the dimers react in situ withtriphenylphosphine–borane to give the disecondary diphosphinecomplexes [RPH–PHR][W(CO)5]2. When R= CH2CH2Cl, a cyclization takes place to givethe diphosphirane complex. A 1,2-diphospholane is obtained for R =Ph by further reaction with 1,3-dibromopropane in the presence ofaqueous K2CO3. [ABSTRACT FROM AUTHOR]

A 2-ethoxycarbonylphosphaferrocene was reduced to thecorresponding 2-hydroxymethyl derivative, which was condensed withpyrrole in a 2:1 ratio in the presence of BF3to give aphosphaferrocene–pyrrole–phosphaferrocene pincer ligand.This tridentate ligand, in turn, reacted with [Rh(acac)(CO)2] to yield a rhodium carbonyl pincer complex. This complex was characterizedby X-ray crystal structure analysis and tested in the hydroformylationof internal olefins. [ABSTRACT FROM AUTHOR]

Two new heterocalixpyrroles are described in which two opposite pyrrole rings are replaced by either two phosphaferrocene or one phosphaferrocene and one thiophene unit to give P–N–P–N or P–N–S–N macrocycles. [ABSTRACT FROM AUTHOR]

Thermolysis of the 1,1′-biphosphirane pentacarbonylmetal complex offers access to 3,4-dihydro-1,2-diphosphete and diphosphorus (P2) intermediates. A control reaction proves that this step-wise reaction is initiated by the dissociation of a W(CO)5 group. DFT calculations predict that further transformations proceed via a transient phosphiranylphosphinidene complex. The formation of the 3,4-dihydro-1,2-diphosphete derivative is thermodynamically favored, while a kinetic process provides the diphosphorus (P2) complex. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations with 1-phenylselenylphosphirane complex 1 provide an insight into phosphirane fragmentation to phosphinidene complexes. FMO and ELF analyses show that the cleavage of two P–C σ bonds of phosphirane proceeds via an asynchronous concerted pathway. Transient [PhSeP–W(CO)5] was generated by dissociation of 1 at 90 °C and trapped with different reagents. The 1-phenoxylphosphirane complex undergoes [1 + 2] retroaddition at a comparatively higher temperature which implies that the lone pair of the adjacent atom center of phosphorus plays a major role in phosphirane fragmentation. [ABSTRACT FROM AUTHOR]

Terminal phosphinidene complexes [RP-W(CO)5], as generated at 60 °C in the presence of copper chloride from the appropriate 7-phosphanorbornadiene complexes, react with secondary phosphine oxides Ar2P(O)H to give the insertion products into the P–H bonds. After metalation with NaH, these products react with aldehydes to give the corresponding phosphaalkenes which are trapped by dimethylbutadiene. [ABSTRACT FROM AUTHOR]

tert‐Butylthiophosphinidene complex [tBuSP‐W(CO)5] was generated by dissociation of 1‐(tert‐butylthio)phosphirane–W(CO)5 complex under mild conditions. The formation of transient [tBuSP‐W(CO)5] was indicated by trapping reactions with 2,3‐dimethyl‐1,3‐butadiene, alkynes, phenanthrene‐9,10‐dione, and methanol. The LUMO of [MeSP‐W(CO)5] is significantly lower in energy than those of [Me2NP‐W(CO)5], [MeOP‐W(CO)5], and [Me2PP‐W(CO)5]. The HOMO of [MeSP‐W(CO)5] contains a significant contribution from the in‐plane lone pair of P and the LUMO shows a typical π* characteristic. Since stabilized by sulfur lone pair and coordinated by W(CO)5, [tBuSP‐W(CO)5] undergoes facile and reversible cycloadditions with alkenes and alkynes. [ABSTRACT FROM AUTHOR]

1-Iminylphosphirane W(CO)5 complexes react with alkenes under an atmosphere of CO at 130 °C to form the original 7-aza-1-phosphanorbornane complexes. The reaction works well with both electron-rich and electron-poor alkenes. On the basis of DFT calculations, we propose a mechanism including the rearrangement of phosphirane into a dipolar five-membered ring and the following cycloaddition of this dipolar intermediate with alkenes. [ABSTRACT FROM AUTHOR]

2-Chloroethylphosphine W(CO)5 complex 1 readily reacts with sodium hydride. With one equivalent of NaH, the parent phosphirane complex 3 is obtained. With more than two equivalents, the phosphiranide complex 2 is exclusively formed. With 1.5 equivalents, a 1 : 1 mixture of 2 and 3 is obtained but 2 readily attacks 3 at the phosphorus atom by splitting of ethylene and by the formation of the P–P complex 4. In turn, the P–P bond of 4 is split by NaH to yield the phosphide complex 8. The phosphiranide complex 2 is a good source for a large variety of functional phosphirane complexes 9. With BrCN, the 1-cyanophosphirane complex 9a is formed. Upon heating it loses its complexing group. Upon hydrolysis, it gives the 1-hydroxyphosphirane complex 12 which dimerizes in basic medium by opening one P–C bond of the ring to give 13. The reaction of 2 with PhPCl2 yields the triphosphorus complex 9g whose molecular structure has been established by X-ray crystal structure analysis. [ABSTRACT FROM AUTHOR]

Secondary phosphirane complexes isomerize above 100 °C to give the corresponding terminal phosphinidene complexes, which can be trapped by alkenes and alkynes. This reaction is a rare instance of the isomerization of a PIII derivative into a PI derivative. It appears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides. [ABSTRACT FROM AUTHOR]

Secondary phosphirane complexes isomerize above 100 °C to give the corresponding terminal phosphinidene complexes, which can be trapped by alkenes and alkynes. This reaction is a rare instance of the isomerization of a PIII derivative into a PI derivative. It appears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides. [ABSTRACT FROM AUTHOR]

Phospholesreact with aldimines at 170 °C in the presence of mild Lewisacids to give C2-bridged biphospholes in good yields. Themechanism includes a series of [1,5] shifts of the P-substituentsaround the phosphole ring, a P–H + aldimine condensation, andthe formation of a transient three-membered ring that dimerizes. [ABSTRACT FROM AUTHOR]

Phospholes react with aldimines in the presence of a mild Lewis acid to C2-bridged biphospholes. [ABSTRACT FROM AUTHOR]