The heterometallic cluster complexes [ Mn,(p-H g Ph) (p-PPh,) (CO) (3), and [Hg{Mn,(p-PPh2)(CO)8)2] (4) have been prepared by reaction of [N( PPh,)2][Mn2(p-PPh2)(CO)8] (1) with, respectively, HgPhCI, HgCI,, and Hg(CN),. Some redistribution reactions of (2), (3), and (4) (in which the Hg atom is three-or four-co-ordinate) have been investigated and are compared with previously studied redistribution reactions of transition-metal-mercury complexes containing two-co-ordinate mercury atoms.

7 2 ir5* at 273 nm (/ = 0.29), and m -5* at 232 nm (/ = 0). These Xmax values are in good agreement with the observed spectrum of hexaphenylpentalene1 23456 (Xx 720 nm (log e 1.95), X2 380 nm (log e 3.99), and X3 310 nm (log e 4.52)) if one assumes that the presence of the phenyl groups shifts each peak to lower energy ( 14) There is some uncertainty as to whether the 285-nm band is due to methylpentalene or to its dimer.'

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ChemInform Abstract The thermal title reaction gives the bis(phosphido)-bridged Mo2 complex (III) (space group P1, Z=2) containing a Mo-Mo double bond. Further decarbonylation leads to the µ-carbonyl derivative (IV) ( P21/n, Z=4) with a Mo-Mo triple bond. Protonation of (III) occurs across the Mo-Mo bond to give the µ-hydrido derivative (V). Oxidation of (III) results in the formation of the trans and cis isomers (VIIa) (P1, Z=2) and (VIIb); the same oxidation products are obtained similarly from (IV) in 1.9 and 52% yield.

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The synthesis, crystal structure, and physical properties of an unprecedented one-dimensional (1D) coordination polymer containing [Fe2(S2C6H2Cl2)4](2-) entities bridged by dicationic [K2(μ-H2O)2(THF)4](2+) units are described. The magnetic properties show that the title compound presents pairwise Fe-Fe antiferromagnetic interactions that can be well reproduced with a S = 1/2 dimer model with an exchange coupling, J = -23 cm(-1). The electrical conductivity measurements show that the title compound is a semiconductor with an activation energy of about 290 meV and two different transitions, both with large hysteresis of about 60 and 30 K at 260-320 K and 350-380 K, respectively. These two transitions are assumed to be due to slight structural changes in the cation-anion interactions. Differential Scanning Calorimetry confirms the presence of both transitions. This compound represents the first sample of a coordination polymer showing electrical bistability.

Convenient methods of preparing complexes of the type (C,H,) Fe(dppe)X (dppe = Ph,PCH,CH,PPh,) are reported and some new complexes are described. The ,' Fe and (for X = SnCI,, SnBr,. and Snl,) the 119Sn Mossbauer spectra of these complexes have been recorded, and are discussed in relation to the spectra of analogous C,H,Fe(CO),X and C,H,Fe(CO) (L)X complexes (L = monodentate phosphine) which have been previously studied.THE substitution of carbonyl groups by tertiary phosphines in complexes of the type C,H,Fe(CO),X has been well studied, and many such substituted complexes have been ~haracterised.l-~ Disubstituted complexes are, however, more difficult to prepare by direct substitution than are monosubstituted complexes, and U.V. irradiation or extended periods of reflux in high boiling solvents are often r e q ~i r e d . ~, ~? ~In consequence, direct substitution can only be used as a method of preparing disubstituted

Structure and Bonding in Gold(i) Compounds. Part 2.t Mossbauer Spectrum of Linear Gold([) Complexes