The reactions of lithiated diphosphanes with transition metal chlorides constitute a new general entry to phosphinophosphinidene complexes: the reaction of Cp2ZrCl2(Cp = C5H5) with tBu2P-P(SiMe3)Li (molar ratio approximately 1:1) yields [mu-(1,2:2-eta-tBu2P=P)[Zr(Cl)Cp2]2]; the reaction of Cp2ZrCl2 with tBu2P-P(SiMe3)Li (molar ratio approximately 1:2) and an excess of PPhMe2 in DME yields the first terminally bonded phosphinophosphinidene complex, [[Zr(PPhMe2)Cp2](eta1-P-PtBu2)].

planar gas-phase molecule being distorted along a coordinate towards UO:Q020 in a matrix.There are many careful and very difficult experiments in the literature. The purpose of this communication is to question how many of the results on high-temperature molecules lead to unambiguous determination of the shape of the free molecule.

No abstract

The first condensed-phase preparation of ternary P-Ch-X cations (Ch=O-Te, X=F-I) is reported: [P5S3X2]+, [P5S2X2]+, and [P4S4X]+ (X=Br, I). [P5S3X2]+ is formed from the reaction of the Ag+/PX3 reagent with P4S3. The [P5S3X2]+ ions have a structure that is related to P4S5 by replacing P=S by P+--X and S in the four-membered ring by P(X). We provide evidence that the active ingredient of the Ag+/PX3 reagent is the (H2CCl2)Ag-X-PX2+ cation. The latter likely reacts with the HOMO of P4S3 in a concerted HOMO-LUMO addition to give the P5S3X2+ ion as the first species visible in situ in the low-temperature 31P NMR spectrum. The [P5S3X2]+ ions are metastable at -78 degrees C and disproportionate at slightly higher temperatures to give [P5S2X2]+ and [P4S4X]+, probably with the extrusion of 1/n (PX)n (X=Br, I). All six new cage compounds have been characterized by multinuclear NMR spectroscopy and, in part, by IR or Raman spectroscopy. The [P5S2X2]+ salts have a nortricyclane skeleton and were also characterized by X-ray crystallography. The structure of the [P4S4X]+ ion is related to that of P4S5 in that the exo-cage P=S bond is replaced by an isoelectronic P+--X moiety.

No abstract

Ir Complexes with P4 Bicyclotetraphosphane and P8 Cunean as Ligands – CO Insertion into an Ir–P Bond The reaction of [Cp*Ir(CO)2] with white phosphorus under photochemical or thermal conditions produces the bicyclotetraphosphane complexes 1 and 2 and the cunean‐type complex 3. The products were characterized by NMR, IR, and mass spectroscopy as well as by X‐ray structure analyses. Complex 1 reacts with CO with insertion into a Ir–P bond to form 2 and finally [Cp*Ir(CO)2].

The structures and relative energies for the basic conformations of silacyclohexane 1 have been calculated using HF, RI‐MP2, RI‐DFT and MM3 methods. All methods predict the chair form to be the dominant conformation and all of them predict structures which are in good agreement with experimental data. The conformational energy surface of 1 has been calculated using MM3. It is found that there are two symmetric lowest energy pathways for the chair‐to‐chair inversion. Each of them consists of two sofa‐like transition states, two twist forms with C1 symmetry (twist‐C1), two boat forms with Si in a gunnel position (C1 symmetry), and one twist form with C2 symmetry (twist‐C2). All methods calculate the relative energy to increase in the order chair < twist‐C2 < twist‐C1 < boat. At the MP2 level of theory and using TZVP and TZVPP (Si atoms) basis sets the relative energies are calculated to be 3.76, 4.80, and 5.47 kcal mol–1 for the twist‐C2, twist‐C1, and boat conformations, respectively. The energy barrier from the chair to the twisted conformations of 1 is found to be 6.6 and 5.7 kcal mol–1 from MM3 and RI‐DFT calculations, respectively. The boat form with Si at the prow (Cs symmetry) does not correspond to a local minimum nor a saddle point on the MM3 energy surface, whereas a RI‐DFT optimization under Cs symmetry constraint resulted in a local minimum. In both cases its energy is above that of the chair‐to‐twist‐C1 transition state, however, and it is clearly not a part of the chair‐to‐chair inversion.

The characterisation of a series of compounds obtained from Woollins' reagent (W.R.) offers a novel approach to organometallic coordination polymers. The syntheses were achieved by nucleophilic ring-opening reactions of W.R. with metal salts and crystallisation using solvent-diffusion techniques. One-dimensional coordination polymers are formed as a result, and we demonstrate that the dimensionality of the polymers can be influenced by using hydrated metal salts or by the construction of heterometallic arrangements.