Different faces of phosphorus chemistry: The reaction of the bicyclotetraphosphine complex 1 with tBuCP leads to the first 1,2,3,4‐tetraphosphaferrocene complex 2 and an allylic P3‐bridged complex 3. Cp′′′=η5‐C5H2tBu3.

The coordination behaviour of 1,2,4‐triphosphaferrocenes [FeCpR(η5‐P3C2tBu2)] [CpR = Cp (1), Cp″′ (2)] towards CuI chloride is significantly influenced by the substitution pattern of the cyclopentadienyl ring attached to iron. The dimeric copper complexes [{FeCp(η5:η1:η1‐P3tBu2C2)}{μ‐CuCl(MeCN)}]2 (3) and [{FeCp″′ (η5:η1:η1‐P3tBu2C2)}(μ‐CuCl)]2 (4), in which two 1,2,4‐triphosphaferrocenes are linked by two CuCl centres to form dimeric complexes were obtained in reactions using a 1:1 stoichiometry. Whereas in 3 a tetra‐coordinated Cu atom is revealed, 4 possesses a threefold‐coordinated Cu atom due to the steric influence of the bulkier Cp″′ ligand. However, if the reaction is carried out with an excess of CuCl in a 1:2 stoichiometry for the Cp derivative 1 the same product 3 is obtained, whereas in the case of a tri‐tert‐butyl‐substituted Cp″′ ligand complex 2 the triphospholyl ring is fragmented under mild conditions to a tetraphosphabutadiene moiety within an iron triple‐decker sandwich complex [{(FeCp″′)2(μ,η4:η4:η1:η1‐P4)}{μ‐CuCl(MeCN)}]∞ (5) embedded in a CuCl polymer matrix.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The reaction of the 1,2,3-triphosphaferrocene [Cp′′′Fe(η 5 -P 3 C 2 (H)Ph)] (1) with the Lewis acidic complex [PtCl 2 (PEt 3 )] 2 yields the monosubstituted derivative [Cp′′′Fe(η 5 -P 3 C 2 (H)Ph){PtCl 2 (PEt 3 )}] (2), in which the Pt moiety is located at the P atom adjacent to the C(H) group of the cyclo-P 3 C 2 ring. Using an excess of the Pt complex no multiple substitution occurs. In contrast, using [W(CO) 5 ] units as Lewis acids results in mono-, di-, and tricoordination at the cyclo-P 3 C 2 ring. The products, [Cp′′′Fe(η 5 -P 3 C 2 (H)Ph){W(CO) 5 } n ] (n ) 1 (3), 2 (4), 3 (5)), have all been spectroscopically characterized, and the substitution patterns of the experimentally found (mono-and disubstituted) isomers are found to be in accordance with the energetically favored derivatives calculated by DFT methods. For these structures the energetically favored rotational conformers have also been calculated. The energetically favored 2,3coordinated isomer 4b could be crystallized, and its structure and that of the tricoordinated derivative 5 were determined by X-ray diffraction methods.

Vielseitige Phosphorchemie: Die Reaktion des Bicyclotetraphosphan‐Komplexes 1 mit PCtBu lieferte gleich zwei neuartige Produkte mit Polyphosphorliganden: den Triphosphaallyl‐verbrückten Zweikernkomplex 2 und das 1,2,3,4‐Tetraphosphaferrocen 3. Cp′′′=η5‐C5H2tBu3.

The coordination behavior of 1,2,4‐triphosphaferrocenes [FeCpR(η5‐P3C2tBu2)] [CpR = Cp (1), Cp″′ = η5‐C5H2tBu3 (3)] towards CuI halides is significantly influenced by the substitution pattern of the cyclopentadienyl ring attached to the iron atom. The reaction of the Cp derivative 1 with CuBr in a 1:1 stoichiometry leads to the dimeric complex [{FeCp(η5:η1:η1‐P3C2tBu2)}{μ‐CuBr(MeCN)}]2 (5b), in which two 1,2,4‐triphosphaferrocenes are linked by two CuBr units. By using a 1:2 stoichiometry, the 1D polymeric compound [{FeCp(η5:η1:η1:η1‐P3C2tBu2)}μ‐{(CuBr)3(MeCN)2}]n (6) is formed in which the triphosphaferrocenes are bridged by (CuBr)2{CuBr(MeCN)2} units. Starting from CuI, independent of the stoichiometry, the cage compound [{FeCp(η5:η1:η1‐P3C2tBu2)}3{Cu(μ‐I)}3{Cu(μ3‐I)}3{Cu(NCMe)}(μ6‐I)](7) is formed. However, if the bulky Cp″′ derivative 3 is used already in a 1:1 stoichiometry with CuBr, a transformation of the initially five‐membered 1,2,4‐triphospholyl ring into a four‐membered 1,2‐diphosphete ligand is observed, which is linked by CuBr moieties forming the dimeric paramagnetic complex [{FeCp″′(η4:η1:η1‐P2C2tBu2)}(μ‐CuBr)]2 (9). Furthermore, applying a 1:2 stoichiometry between 3 and CuX (X = Br, I) the complete fragmentation of the 1,2,4‐triphospholyl ring under mild conditions into a tetraphosphabutadiene ligand is observed. In the formed 1D polymeric complexes [{(FeCp″′)2(μ,η4:η1:η1‐P4)}{(μ‐CuX)2(MeCN)}]n [X = Br (10a), I (10b)] this ligand represents now the middle deck of the triple‐decker sandwich complexes linked by four‐membered [(CuX)2(CH3CN)] moieties. Moreover, the reaction of the Cp derivative 1 with the Ag salt of the weakly coordinating anion [Al{OC(CF3)3}]4– leads to the dimeric Ag(CH3CN)‐bridged dicationic product [{FeCp(η5‐P3C2tBu2)}Ag(MeCN)]2[Al{OC(CF3)3}4]2 (11).