The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : IX. Hexameric organoaluminum imides by reaction of (HAIN-iso-C3H7)6 with trialkylaluminums

(HAlN-iso-C₃H₇)₆ reacts with Al(CH₃)₃ or Al(C₂H₅)₃ to give compounds in which the hydridic hydrogens are partially or completely replaced by alkyl groups. The degree of alkylation depends on the reaction conditions and on the nature of the trialkylaluminum. Pure crystalline (CH₃AlN-iso-C₃H₇)₆, its crystallization product with [(CH₃AlN-iso-C₃H₇)₅(HAlN-iso-C₃H₇)] and a mixture of [(C₂H₅AlN-iso-C₃H₇)₄(HAlN-iso-C₃H₇)₂] isomers have been isolated. The reaction of Al(CH₃)₃ or Al(C₂H₅)₃ with iso-C₃H₇NH₂ gives tetramers (CH₃AlN-iso-C₃H₇)₄ and (C₂H₅AlN-iso-C₃H₇)₄.     

Halfsandwich Carbonylmetal Complexes of Vanadium,Chromium, and Manganese Containing Tri(1‐cyclohepta‐2, 4, 6‐trienyl)phosphane,P(C7H7)3

The photo‐induced substitution of a CO ligand has been used to prepare the halfsandwich complexes (η³‐C₃H₅)V(CO)₄[P(C₇H₇)₃] ( 1 ), (η⁵‐C₅H₅)V(CO)₃[P(C₇H₇)₃] ( 2 ), (η⁷‐C₇H₇)V(CO)₂[P(C₇H₇)₃] ( 3 ), (η⁶‐C₆H₃Me₃)Cr(CO)₂[P(C₇H₇)₃] ( 4 ), and (η⁵‐C₅H₅)Mn(CO)₂[P(C₇H₇)₃] ( 7 ), in which the olefinic phosphane is coordinated as a conventional two‐electron ligand through the lone pair of electrons at phosphorus. Some analogues, which are permethylated at the aromatic ring ( 2* , 4* , 7* ), were included for comparison. Subsequent photo‐elimination of another CO group from 4 or 7 converts the olefinic phosphane into a chelating four‐electron ligand, leading to (η⁶‐C₆H₃Me₃)Cr(CO)[P(C₇H₇)₂(η²‐C₇H₇)] ( 5 ) and (η⁵‐C₅H₅)Mn(CO)[P(C₇H₇)₂(η²‐C₇H₇)] ( 8 ), respectively. The η²‐coordinated double bond in 5 and 8 can be displaced by trimethylphosphite to give (η⁶‐C₆H₃Me₃)Cr(CO)[P(C₇H₇)₃][P(OMe)₃] ( 6 ) and (η⁵‐C₅H₅)Mn(CO)[P(C₇H₇)₃][P(OMe)₃] ( 9 ). The ³¹P and ¹³C NMR spectra of all complexes are discussed, and X‐ray structure analyses for 2 and 8 are presented. Prolonged irradiation of 7 and 8 led to a di(cycloheptatrienyl)phosphido‐bridged dimer, {(η⁵‐C₅H₅)Mn(CO)[P(C₇H₇)₂]}₂( 10 ).     

Tri(1-cyclohepta-2,4,6-trienyl)phosphan,P(C7H7)3 und Tetra(1-cyclohepta-2,4,6-trienyl)phosphonium-tetrafluoroborat, [P(C7H7)4]BF4

Tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C₇H₇)₃, and Tetra(1-cyclohepta-2,4,6-trienyl)phosphonium Tetrafluoroborate, [P(C₇H₇)₄]BF₄ The reaction of tris(trimethylsilyl)phosphane, P(SiMe₃)₃, with tropylium bromide, C₇H₇⁺Br^?, in polar solvents such as dichloromethane or tetrahydrofuran gives P(C₇H₇)₃ ( 1 ) and [P(C₇H₇)₄]Br ( 2a ). According to the X-ray crystallographic structure determinations, all 1-cyclohepta-2,4,6-trienyl substituents are present in the boat conformation in both P(C₇H₇)₃ ( 1 ) and the phosphonium salt, [P(C₇H₇)₄]BF₄ ( 2b ). The boat-shaped C₇H₇ rings are significantly more flattened if the phosphorus occupies the axial rather than the equatorial position at the ring substituent. Addition of a chalcogen to the lone pair at the central phosphorus atom of 1 leads to the chalcogena-phosphoranes EP(C₇H₇)₃ (E = O ( 3a ), S ( 3b ), Se ( 3c )). The new 1-cyclohepta-2,4,6-trienyl-phosphorus compounds 1, 2 b and 3a–c were characterized by their ¹H, ¹³C, and ³¹P NMR spectra in C₆D₆ solution.     

Reaktionen der Cycloheptatrienylkomplexe [η7-C7H7W(CO)3]BF4 und η7-C7H7Mo(CO)2 Br mit Neutralliganden und die elektrochemische Reduktion des Wolframkomplexes

Reactions of the Cycloheptatrienyl Complexes [η⁷-C₇H₇W(CO)₃]BF₄ and η⁷-C₇H₇Mo(CO)₂Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η⁷-C₇H₇M(CO)₂L][BF₄] (L = P(C₆H₅)₃, As(C₆H₅)₃, Sb(C₆H₅)₃ for M = W and L = N₂H₄ for M = Mo) were synthesized and characterisized. The iodide η⁷-C₇H₇W(CO)₂I reacts with the diphosphine ((C₆H₅)₂PCH₂)₂ to give the trihapto complex η³-C₇H₇ W(CO)₂I((C₆H₅)₂PCH₂)₂. In the case of η⁷-C₇H₇Mo(CO)₂ Br reaction with hydrazine leads to the substitution product [η⁷-C₇H₇ Mo(CO)₂N₂H₄]^⊕, which can be stabilized by large anions. The binuclear complex [C₇H₇W(CO)₃]₂ has been synthesized electrochemically.     

Preparation of closo-10-vertex transition metal carbaboranes

The synthesis of the ten-vertex closo-metallacarboranes 10-η₅H₅Ni-η⁴-1-CB₈H₉, 6-η⁵-C₅H₅Ni-η⁵-1-CB₈H₉, (η⁵-C⁵Ni)₂-1-CB₇H₈, and [2-η⁵-C₅H₅Co-η⁵-1-CB₈H₉]⁻ from 4-CB₈H₁₄ is reported.     

Die Molekül- und Kristallstrukturen von (CO)4 W(μ-S-t-C4H9)2W(CO)4, η7-C7H7W(μ-SC6H4CH3)3W(CO)3 und η7-C7H7W(μ-S-n-C4H9)3W(CO)(μ-S-n-C4H9)2W(CO)4

Molecular and Crystal Structures of (CO)₄W(μ-S-t-C₄H₉)₂W(CO)₄, η⁷-C₇H₇W(μ-SC₆H₄CH₃)₃W(CO)₃ and η⁷-C₇H₇W(μ-S-n-C₄H₉)₃W(CO)(μ-S-n-C₄H₉)₂W(CO)₄ The molecular structures of the two binuclear complexes (CO)₄W(μ-S-t-C₄H₉)₂W(CO)₄ and η⁷-C₇H₇W(μ-SC₆H₄CH₃)₃W(CO)₃ and of the tungsten cluster η⁷-C₇H₇W(μ-S-n-C₄H₉)₃W(CO)-(μ-S-n-C₄H₉)₂W(CO)₄ respectively are described. In the nonlinear trinuclear cluster the central tungsten atom is connected to the two tungsten atoms by two and three μ-S-n-C₄H₉ bridges respectively and additionally by one W? W bond each. The coordination sphere of the W atoms is completed by a η⁷-C₇H₇ ring and four CO groups respectively; the central tungsten carries an additional CO group.     

ÜBER STERISCH SPERRIGE ORGANOPHOSPHORVERBINDUNGEN: ISOPROPYL-SUBSTITUIERTE THIOPHOSPHORYLBROMIDE

Abstract

Durch selektive Grignardierungsreaktionen werden Verbindungen des Typs R(i-C₃H₇)PBr erhalten und in R(i-C₃H₇)P(S)Br überführt. Die chemische Verschiebung δ p in RR'P(S)Br (R,R' = CH₃, C₂H₅, i-C₃H₇, t-C₄H₉) wächst linear mit der Zahl der ß-ständigen Methylgruppen in R und R'. AB₃C₃X-Spektren der i-C₃H₇P-Struktur-elemente werden berechnet.

Selective Grignard-type reactions lead to R(i-C₃H₇)PBr which are converted to R(i-C₃H₇)P(S)Br. Chemical shift values δ p in RR'P(S)Br (R,R' = CH₃, C₂H₅, i-C₃H₇, t-C₄H₉) increase linearly with the number of ß-methyl groups in R and R'. AB₃C₃X-spectra are calculated for i-C₃H₇P-moieties.     

The reactions of [Co(η-C5H5)(CO)(L)] (L = R3P or RNC) with carbon disuphide and organoisothiocyanates

The reactions of [Co(η-C₅H₅)(CO)(PR₃)] or [Co(η-C₅GH₅)(CO)₂]/R₃P mixtures (R = alkyl or aryl) with CS₂ in refluxing CS₂ or CS₂/toluene gives rise to [Co(η-C₅H₅)(PR₃)(CS)], [Co(η-C₅H₅)(PR₃)(CS₂)], [Co(η-C₅H₅)(PR₃)(CS₃)], and [Co₃(η-C₅H₅)₃ (CS)(S)] in reasonable yields. The corresponding reactions using PhNCS give [Co(η-C₅H₅)(PPh₃)(PhNCS)] and a polymeric species which appears to be [Co₄(η-C₅H₅)₄ (PhNCS)]. Similar products are obtained with [Co(η-C₅H₅)(CO)(CNR)] or [Co(η0C₅H₅)(CO)₂]/RNC mixtures.     

3-D Hydrogen-bonded networks of metal complexes with chelidamic acid and 1,10-phenanthroline: syntheses,structures, and optical properties

The title complexes, (C₁₂H₈N₂) ? [La(C₇H₃NO₅)(C₇H₄NO₅) ? 3H₂O] ? 1.75H₂O (1), (C₁₂H₈N₂) ? [Pr(C₇H₃NO₅)(C₇H₄NO₅) ? 3H₂O] ? 2H₂O (2), (C₁₂H₈N₂)[Nd(C₇H₃NO₅)(C₇H₄NO₅) ? 3H₂O] ? 2.25H₂O (3), and (C₁₂H₈N₂) ? [Fe(C₇H₃NO₅)(C₇H₄NO₅)] ? 2H₂O (4), were synthesized and characterized by single-crystal X-ray diffraction. The crystal structures of 1–3 reveal that they are isomorphous, among which the metal atoms are all nine-coordinate with distorted tricapped trigonal prismatic coordination geometries. The Fe is six-coordinate with a distorted octahedron by two chelidamic acid ligands in 4. Complexes 1–4 are formed into 3-D networks by H-bonds and π–π stacking interactions. The fluorescence spectra of 1–3 were investigated and all exhibit strong luminescence.     

Infrared and NMR Spectroscopic Fingerprints of the Asymmetric H7+O3 Complex in Solution

Infrared (IR) absorption in the 1000–3700 cm⁻¹ range and ¹H NMR spectroscopy reveal the existence of an asymmetric protonated water trimer, H₇⁺O_3, in acetonitrile. The core H₇⁺O₃ motif persists in larger protonated water clusters in acetonitrile up to at least 8 water molecules. Quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations reveal irreversible proton transport promoted by propagating the asymmetric H₇⁺O₃ structure in solution. The QM/MM calculations allow for the successful simulation of the measured IR absorption spectra of H₇⁺O₃ in the OH stretch region, which reaffirms the assignment of the H₇⁺O₃ spectra to a hybrid-complex structure: a protonated water dimer strongly hydrogen-bonded to a third water molecule with the proton exchanging between the two possible shared-proton Zundel-like centers. The H₇⁺O₃ structure lends itself to promoting irreversible proton transport in presence of even one additional water molecule. We demonstrate how continuously evolving H₇⁺O₃ structures may support proton transport within larger water solvates.     

Salicylate of Uranium

The reactions of uranium pentaethoxide with salicylic acid have been carried out in different stoichiometric ratios, yielding products of the type, U(OEt)₃(C₇H₄O₃), U(OEt)(C₇H₄O₃)₂, U(C₇H₄O₂)₂(C₇H₄O₃), and U₂(C₇H₄O₃)₃. A detailed study of the complexation reactions of uranyl ion with salicylic acid have also been made by potentiomertic and conductometric methods. The formation of 1:1 and 1:2 complexes have been confirmed by preparative studies. Two compounds, viz. (C₅H₆N)₂UO₂(C₇H₄O₃)₂ (NH₄)₂UO₂(C₇H₄O₃)₂ have been isolated.     

Equilibrium phase behavior of aqueous two-phase systems containing 17R4/L64 and citrates

The cloud points (CPs) of the copolymers 17R4 and L64 were first measured, and then the effects of salts ((NH₄)₃C₆H₅O₇, K₃C₆H₅O₇) on 17R4 and L64 were researched. After finishing the work described above, the temperature (278.15, 283.15, and 288.15) K of aqueous two-phase systems was determined, which consist of 17R4-(NH₄)₃C₆H₅O₇, 17R4-K₃C₆H₅O₇, L64-(NH₄)₃C₆H₅O₇, and L64-K₃C₆H₅O₇. Finally, the liquid–liquid equilibrium (LLE) data of binodal curve and the tie line for 17R4-(NH₄)₃C₆H₅O₇ aqueous two- phase systems (ATPSs) 17R4-K₃C₆H₅O₇ ATPSs, L64-(NH₄)₃C₆H₅O₇ ATPSs, and L64-K₃C₆H₅O₇ ATPSs were obtained. Nonlinear fitting of the empirical equation was used for making the diagram. The results showed that the change in the size of the two-phase areas increases with the increase of temperature. The capacity of the salts to induce phase segregation follows the Hofmeister series, that is, K₃C₆H₅O₇?>?(NH₄)₃C₆H₅O₇. In addition, the findings also showed that the phase separation ability of 17R4 is better than that of L64.     

π-Cyclopentadienyl-like derivatives of cobalt: synthesis of indenyl- and fluorenyl-bis(phosphite)-cobalt(I)

The compounds {Co(C₉H₇)[P(OR)₃]₂} (C₉H₇ = indenyl) and {Co(C₁₅H₉)[P(OR)₃]₂} (C₁₃H₉ = fluorenyl) (R = C₂H₅, i-C₃H₇) have been prepared by treating {CoBr[P(OC)₃]₃} with NaC₉H₇ and NaC₁₃H₉, respectively. The ¹H, ¹³C NMR, IR, and mass spectra of the new compounds are discussed. The preparation of {Co(C₉H₇)(CO)[P(OR)₃]} and {Co(C₁₃H₉)(CO)[P)OR)₃]} is also reported.     

Chemical syntheses with metal atoms

Metal evaporation syntheses of [Cr(C₇H₇)(C₇H₁₀)], [Cr(C₇H₈)(PF₃)₃], metal carbonyls, and anhydrous metal acetylacetonates are described.     

Photoacoustic spectra of Nd(TFA)3 · 2H2O and Nd(HFA)3 · 2H2O

A new synthesis of trisfluoroacetylactone (TFA) and hexafluoroacetylactone (HFA) Nd complexes: Nd(TFA)₃ · 2H₂O and Hd(HFA)₃ · 2H₂O is reported. The photoacoustic (PA) spectra in the 300–800 nm region of the compounds NdCl₃ · 6H₂O, Nd(TFA)₃ · 2H₂O and Nd(HFA)₃ · 2H₂O are reported. The PA absorption bands are assigned and their relative intensities represented by intensity branching vectors are calculated. The perturbation of the ligand on the energy levels of Nd³⁺ ion is discussed and a model of the relaxation process of Nd(HFA)₃ · 2H₂O is proposed based on its PA and absorption spectra.     

Reactions of the cycloheptatrienyl complexes [MX(CO)2(η-C7H7)] (M=Mo, X=Br; M=W, X=I) with CNBu: X-ray crystal structure of [WI(CO)2(CNBu)2(η-C7H7)]

Reaction of [MX(CO)₂(η⁷-C₇H₇)] (M=Mo, X=Br; M=W, X=I) with two equivalents of CNBu^t in toluene affords the trihapto-bonded cycloheptatrienyl complexes [MX(CO)₂(CNBu^t)₂(η³-C₇H₇)] (1, M=Mo, X=Br; 2, M=W, X=I). The X-ray crystal structure of 2 reveals a pseudo-octahedral molecular geometry with an asymmetric ligand arrangement at tungsten in which one CNBu^t is located trans to the η³-C₇H₇ ring. Treatment of 2 with tetracyanoethene results in 1,4-cycloaddition at the η³-C₇H₇ ring to give [WI(CO)₂(CNBu^t)₂{η³-C₉H₇(CN)₄}], 3. The principal reaction type of the molybdenum complex 1 is loss of carbonyl and bromide ligands to afford substituted products [MoBr(CNBu^t)₂(η⁷-C₇H₇)] 4 or [Mo(CO)(CNBu^t)₂(η⁷-C₇H₇)]Br. Reaction of [MoBr(CO)₂(η⁷-C₇H₇)] with one equivalent of CNBu^t in toluene at 60°C affords [MoBr(CO)(CNBu^t)(η⁷-C₇H₇)], 5, which is a precursor to [Mo(CO)(CNBu^t)(NCMe)(η⁷-C₇H₇)][BF₄], 6, by reaction with Ag[BF₄] in acetonitrile. In contrast with the parent dicarbonyl systems [MoX(CO)₂(η⁷-C₇H₇)], complexes of the Mo(CO)(CNBu^t)(η⁷-C₇H₇) auxiliary, 5 and 6, do not afford observable η³-C₇H₇ products by ligand addition at the molybdenum centre.     

Molecular Structures of Mononuclear Rhodium Complexes Containing the Polydentate Ligand Tri(1‐cyclohepta‐2,4,6‐trienyl)phosphane,P(C7H7)3. Classification according to the 31P Chemical Shifts

The olefinic phosphane P(C₇H₇)₃ ( 5 ) behaves as a tetradentate tripod ligand in [RhCl{P(η²‐C₇H₇)₃}] ( 6 ), using all 3 cyclohepta‐2,4,6‐trienyl substituents as η²‐coordinating side‐arms. Nucleophilic displacement of the one‐electron chloro ligand by halides or pseudohalides to give [RhX{P(η²‐C₇H₇)₃}] (X = Br ( 7a ), I ( 7b ), N₃ ( 7c ), NCO ( 7d )) leaves the basket‐like framework [Rh{P(η²‐C₇H₇)₃}] intact. Reactions of 6 with three‐electron ligands result in decomplexation of one cyclohepta‐2,4,6‐trienyl ring and formation of [Rh(L³){P(C₇H₇)(η²‐C₇H₇)₂}] (L³ = acetylacetonate ( 8 ), 2‐carboethoxy cyclopentanonate ( 8a )), reactions of 6 with five‐electron ligands such as η⁵‐C₅H₅ cause decomplexation of two olefinic side‐arms to give [Rh(L⁵){P(C₇H₇)₂(η²‐C₇H₇)}] (L⁵ = η⁵‐C₅H₅ (Cp) ( 9 ), η⁵‐C₅H₄^tBu ( 9a )). The last remaining chelate ring in 9 is opened by pressure‐carbonylation to give the adduct [Rh(Cp)(CO){P(C₇H₇)₃}] ( 10 ) or by oxidative addition of halogens to form [Rh(Cp)X₂{P(C₇H₇)₃}] (X = Br, I). The full set of ¹H, ¹³C, ³¹P, and ¹⁰³Rh NMR data is given for the prototype complexes 7a , 8 , 9 , and 10 , and the molecular geometries of the [Rh{P(C₇H₇)₃}] fragments are compared on the basis of the X‐ray structural determinations of 6 , 8 , 8a , 9 , 9a , and 10 . The chemical shifts δ(³¹P) provide a reliable parameter for the prediction of the molecular structures of the rhodium complexes in solution.     

Synthesis and Characterization of O,O'-Bis(α-Naphthyl, β-Naphthyl,and 2, 3, 5-Trimethylphenyl)Dithiophosphate Ligands

Abstract

O,O′-Bis(α-Naphthyl, β-Naphthyl and 2,3,5-trimethylphenyl) dithiophosphate ligands have been isolated as triethylammonium salts, (α-C₁₀H₇O-, β-C₁₀H₇O, and (CH₃)₃C₆H₂O)₂PS₂HNEt₃, by the reaction of α-C₁₀H₇OH, β-C₁₀H₇OH, or (CH₃)₃C₆H₂OH with P₂S₅ in presence of Et₃N, in 4:1:2 molar ratio in chloroform under anhydrous conditions. Acidic form of these ligands, (α-C₁₀H₇O-, β-C₁₀H₇O-, or (CH₃)₃C₆H₂O)₂PS₂H, have been obtained by the direct reaction of α-C₁₀H₇OH, β-C₁₀H₇OH-, or (CH₃)₃C₆H₂OH with P₂S₅ in 4:1 molar ratio in presence of microwaves under solvent-free conditions. Both forms of the ligands have been converted into corresponding sodium salts, (α -C₁₀H₇O-, β-C₁₀H₇O-, or (CH₃)₃C₆H₂O)₂PS₂Na. These compounds have been characterized by elemental analyses (C, H, N, and S) and mass, IR, and NMR (¹H, ¹³C and ³¹P) spectroscopic studies.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Formal chromium–chromium triple bonds and bent rings in the binuclear cycloheptatrienylchromium carbonyls (C7H7)2Cr2(CO)n (n = 6, 5, 4, 3, 2, 1, 0): A density functional theory study

Binuclear cycloheptatrienylchromium carbonyls of the type (C₇H₇)₂Cr₂(CO)_n (n = 6, 5, 4, 3, 2, 1, 0) have been investigated by density functional theory. Energetically competitive structures with fully bonded heptahapto η⁷-C₇H₇ rings are not found for (C₇H₇)₂Cr₂(CO)_n structures having two or more carbonyl groups. This result stands in contrast to the related (C_nH_n)₂M₂(CO)_n (M = Mn, n = 6; M = Fe, n = 5; M = Co, n = 4) systems. Most of the predicted (C₇H₇)₂Cr₂(CO)_n structures have bent trihapto or pentahapto C₇H₇ rings and CrCr distances in the range 2.4–2.5 Å suggesting formal triple bonds. In some cases rearrangement of the heptagonal C₇H₇ ring to a tridentate cyclopropyldivinyl or tridentate bis(carbene)alkyl ligand is observed. In addition structures with CO insertion into the C₇H₇–Cr bond are predicted for (C₇H₇)₂Cr₂(CO)_n (n = 6, 4, 2). The global minima found for the (C₇H₇)₂Cr₂(CO)_n derivatives for n = 6, 5, and 4 are (η⁵-C₇H₇)(OC)₂CrCr(CO)₄(η¹-C₇H₇), (η³-C₇H₇)(OC)₂CrCr(CO)₃(η^2,1- C₇H₇), and (η⁵-C₇H₇)₂Cr₂(CO)₄, respectively. The global minima for (C₇H₇)₂Cr₂(CO)_n (n = 3, 2) have rearranged C₇H₇ groups. Singlet and triplet structures with heptahapto η⁷-C₇H₇ rings are found for the dimetallocenes (η⁷-C₇H₇)₂Cr₂(CO) and (η⁷-C₇H₇)₂Cr₂, with the singlet structures being of much lower energies in both cases.     

Untersuchungen zur reaktivität von metall-π-komplexen : XVIII. Elektrophile und nucleophile additionsreaktionen an siebenringliganden in tricarbonylmolybdän-komplexen: Synthese von [C7H9Mo(CO)3]BF4, C7H9Mo(CO)3Cl und [C7H9P(C6H5)3]BF4

C₇H₈Mo(CO)₃ reacts with HBF₄ and HCl by protonation of the ring ligand and formation of [C₇H₉Mo(CO)₃]BF₄ (I) and C₇H₉Mo(CO)₃Cl (II), respectively. The compounds are characterised by means of their IR and NMR data. The reaction of I with P(C₆H₅)₃ does not lead, as expected, to [C₇H₉Mo(CO)₃P(C₆H₅)₃]BF₄ (III) but to the phosphonium salt [C₇H₉P(C₆H₅)₃]BF₄ (IV), i.e. nucleophilic addition of the phosphine at the cycloheptadienyl group takes place. The structure of IV has been determined by ¹³C NMR measurements.