Schrittweise Erweiterung eines Cp*-Rings am Pentelidenkomplex und stereoselektive Bildung von Triphosphanen

A novel access to phosphanylidene-phosphorane complexes via P-donor substitution and a detailed bonding analysis

Phospha-Wittig reagents such as phosphanylidene-phosphoranes and their transition metal complexes are of great interest as sources of P1 building blocks but the access is still limited. Herein, we describe a new access to phosphanylidene-phosphorane complexes starting from the N-methylimidazole-to-phosphinidene complex adduct. The complexes were studied electrochemically and theoretically, also with respect to their 31P NMR data, and the P-P bonds were evaluated by various DFT-derived descriptors.

Ring Expansions of Nonpolar Polyphosphorus Rings

The reaction of the phosphinidene complex [Cp*P{W(CO)₅ }₂ ] (1 a) (Cp*=C₅ Me₅ ) with the anionic cyclo-P_n ligand complex [(η³ -P₃ )Nb(ODipp)₃ ]^- (2, Dipp=2,6-diisopropylphenyl) resulted in the formation of [{W(CO)₅ }₂ {μ₃ ,η^3:1:1 -P₄ Cp*}Nb(ODipp)₃ ]^- (3), which represents an unprecedented example of a ring expansion of a polyphosphorus-ligand complex initiated by a phosphinidene complex. Furthermore, the reaction of the pnictinidene complexes [Cp*E{W(CO)₅ }₂ ] (E=P: 1 a, As: 1 b) with the neutral complex [Cp'''Co(η⁴ -P₄ )] (Cp'''=1,2,4-tBu₃ C₅ H₂ ) led to a cyclo-P₄ E ring (E=P, As) through the insertion of the pentel atom into the cyclo-P₄ ligand. Starting from 1 a, the two isomers [Cp'''Co(μ₃ ,η^4:1:1 -P₅ Cp*){W(CO)₅ }₂ ] (5 a,b), and from 1 b, the three isomers [Cp'''Co(μ₃ ,η^4:1:1 -AsP₄ Cp*){W(CO)₅ }₂ ] (6 a-c) with unprecedented cyclo-P₄ E ligands (E=P, As) were isolated. The complexes 6 a-c represent unique examples of ring expansions which lead to new mixed five-membered cyclo-P₄ As ligands. The possible reaction pathways for the formation of 5 a,b and 6 a-c were investigated by a combination of temperature-dependent ³¹ P{¹ H} NMR studies and DFT calculations.

Insight into the Reaction of a Dinuclear Phosphinidene Complex with Nitriles

The phosphinidene complex [Cp*P{W(CO)5}2] (1; Cp*=C5 Me5 ) reacted with malononitrile to give the 1,2-dihydro-1,3,2-diazaphosphinine derivative 2. The reaction of 1 with 1,4-benzodinitrile gave [1,4-{{W(CO)5}2 P-N=C(Cp*)}2 (C6 H4)] (3), the first example of a cumulene-like aminophosphinidene complex. The reaction of 1 with aniline gave the aminophosphinidene complex [(Ph)N(H)P{W(CO)5}2] (4). To compare the reactivity of benzonitrile and aniline with 1, the phosphinidene complex 1 was reacted with three different isomers of aminobenzonitrile (2-, 3-, and 4-aminobenzonitrile). These reactions gave an insight into the reaction pathway of 1 with benzonitrile derivatives. Compounds 5, 6 a, 6 b, and 7, which are derivatives of 1,2-dihydro-1,3,2-diazaphosphinine or benzo-2H-1,2-azaphospholes, were, as well as all other products, characterized by mass spectrometry, NMR and IR spectroscopy, and X-ray structure analysis.

Yttrium complexes of arsine, arsenide, and arsinidene ligands

Deprotonation of the yttrium-arsine complex [Cp'3Y{As(H)2Mes}] (1) (Cp'=η(5)-C5H4Me, Mes=mesityl) by nBuLi produces the μ-arsenide complex [{Cp'2Y[μ-As(H)Mes]}3] (2). Deprotonation of the As-H bonds in 2 by nBuLi produces [Li(thf)4]2[{Cp'2Y(μ3-AsMes)}3Li], [Li(thf)4]2[3], in which the dianion 3 contains the first example of an arsinidene ligand in rare-earth metal chemistry. The molecular structures of the arsine, arsenide, and arsinidene complexes are described, and the yttrium-arsenic bonding is analyzed by density functional theory.

Reactivity of bridged pentelidene complexes with isonitriles: a new way to pentel-containing heterocycles

The reaction of [Cp*E{W(CO)5 }2 ] (E=P (1 a), As (1 b); Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with isonitriles RNC (R=tBu, cyclohexyl (Cy), nBu) depends on the steric demand of the substituent at the isonitrile as well as on the stoichiometry of the starting materials. With tBuNC only the Lewis acid/base adducts [Cp*E{W(CO)5 }2 (CNtBu)] (E=P (2 a), As (2 b)) are formed. The use of Cy and n-butylisonitrile leads first to the formation of the Lewis acid/base adduct, but only at low temperatures. At ambient temperatures, a rearrangement occurs and bicyclo[3.2.0]heptane derivatives of the type [{C(Me)C(CH2 )C(Me)C(Me)C(Me)}C(NR)- E{W(CO)5 }2 ] (E=P, As; R=Cy, nBu) (3 a-Cy, 3 b-Cy, 3 a-nBu and 3 b-nBu) are obtained. The use of a further equivalent of isonitrile results in products revealing two new structural motifs, the four-membered ring derivatives [C(Cp*)N(R)C(NR)E{W(CO)5 }2 ] (4: E=P, As; R=Cy, nBu) and the bicyclic complexes [[{C(Me)C- (CH2 )C(Me)C(Me)C(Me)}C(NR)2 - E{W(CO)5 }2 ] (5: E=As; R=Cy). The reaction pathway depends on the substituent at the isonitrile. By treatment of 1 a with two equivalents of CyNC only a 2H-1,3-azaphosphet complex 4 a-Cy (E=P; R=Cy) is formed. Treatment of 1 b with two equivalents of CyNC exclusively leads to the complex 5 b-Cy (E=As; R=Cy). Treatment of 1 a with two equivalents of nBuNC results in a mixture of complexes, the 2H-1,3-azaphosphet 4 a-nBu (E=P; R=nBu) and the bicyclic complex 5 a-nBu (E=P; R=nBu). For the arsenidene complex 1 b a mixture of the 2H-1,3-azarsete complex 4 b-nBu (E=As; R=nBu) and the bicyclic complex 5 b-nBu (E=P, As; R=Cy, nBu) is obtained. Complex 4 b-nBu is the first example of a 2H-1,3-azarsete complex. All products have been characterized by using mass spectrometry, NMR spectroscopy, and X-ray diffraction analysis.