Di-tert-butyldiphosphatetrahedrane as a Source of 1,2-Diphosphacyclobutadiene Ligands.

Reactions of di-tert-butyldiphosphatetrahedrane (1) with cycloocta-1,5-diene- or anthracene-stabilised metalate anions of iron and cobalt consistently afford complexes of the rarely encountered 1,2-diphosphacyclobutadiene ligand, which have previously been very challenging synthetic targets. The subsequent reactivity of 1,2-diphosphacyclobutadiene cobaltates toward various electrophiles has also been investigated and is compared to reactions of related 1,3-diphosphacyclobutadiene complexes. The results highlight the distinct reactivity of such isomeric species, showing that the 1,2-isomers can act as precursors for previously unknown triphospholium ligands.

Construction of alkyl-substituted pentaphosphido ligands in the coordination sphere of cobalt.

Rare mono- and diorganopentaphosphido cobalt complexes are accessible by P-P condensation using the unprecedented, reactive cobalt-gallium tetraphosphido complex [K(dme){(BIAN)Co(μ-η:η-P)Ga(nacnac)}] (). Compound was prepared in good yield by reaction of [K(EtO){(BIAN)Co(η-1,5-cod)}] [, BIAN = bis(mesitylimino)acenaphthene diimine, cod = 1,5-cyclooctadiene] with [Ga(nacnac)(η-P)] (nacnac = CH[CMeN(2,6-iPrCH)]). Reactions with RPCl (R = iPr, Bu, and Cy) selectively afford [(BIAN)Co(-PR)] (), which feature η-coordinated 1,1-diorganopentaphosphido ligands.

Mono- and dinuclear tetraphosphabutadiene ferrate anions.

Reduction of [CpFe(μ-Br)] (1, Cp = C(CH-4-Et)) by potassium napthalenide, followed by the addition of white phosphorus, affords [K(18-c-6){CpFe(η-P)}] (2, 18-c-6 = [18]crown-6), which features a planar cyclo-P ligand. The related diiron complex [Na(THF)(CpFe)(μ,η-P)] (3) was obtained by reducing 1 with sodium amalgam in the presence of P. Protonation of 3 affords [Na(THF)][(CpFe)(μ,η-P)(H)] (4), while the reaction of 3 with trimethylchlorosilane gives the nortricyclane compound P(SiMe) as the main product.

Influence of Ring-Expanded N-Heterocyclic Carbenes on the Structures of Half-Sandwich Ni(I) Complexes: An X-ray, Electron Paramagnetic Resonance (EPR), and Electron Nuclear Double Resonance (ENDOR) Study.

Potassium graphite reduction of the half-sandwich Ni(II) ring-expanded diamino/diamidocarbene complexes CpNi(RE-NHC)Br gave the Ni(I) derivatives CpNi(RE-NHC) (where RE-NHC = 6-Mes (1), 7-Mes (2), 6-MesDAC (3)) in yields of 40%-50%. The electronic structures of paramagnetic 1-3 were investigated by CW X-/Q-band electron paramagnetic resonance (EPR) and Q-band H electron nuclear double resonance (ENDOR) spectroscopy. While small variations in the g-values were observed between the diaminocarbene complexes 1 and 2, pronounced changes in the g-values were detected between the almost isostructural species (1) and diamidocarbene species (3).

Selective P Activation by a Highly Reduced Cobaltate: Synthesis of Dicobalt Tetraphosphido Complexes.

Although the chemistry of transition metal polyphosphide anions has attracted significant attention, there are few reports of studies in which such species have been synthesized directly from white phosphorus. [K(OEt ) {Co(BIAN)(cod)}] (1, BIAN=1,2-bis(2,6-diisopropylphenylimino)acenaphthene, cod=1,5-cyclooctadiene), which is readily prepared by ligand exchange from [K(thf) {Co(cod) }], reacts with P to afford [{K(thf)} {(BIAN)Co} (μ-η :η -P )] (2 a) in 61 % yield (isolated product). [{K(OEt )} {(BIAN)Co} (μ-η :η -P )] (2 b) and [K([18]crown-6)(MeCN)] [{(BIAN)Co} (μ-η :η -P )] (2 c) were obtained by recrystallizing 2 a from diethyl ether and acetonitrile (and using [18]crown-6 in case of 2 c).

Insertion of phenyl isothiocyanate into a P-P bond of a nickel-substituted bicyclo[1.1.0]tetraphosphabutane.

A new reaction mode for bicyclo[1.1.0]tetraphosphabutanes is reported.

Germacyclobutenes: generation by 1,1-carbalumination or 1,1-carbagallation and their photophysical properties.

Aluminium- and gallium-functionalised alkenylalkynylgermanes, R(1) 2 Ge(C≡C-R(2) )[C{E(CMe3 )2 }=C(H)-R(2) ] (E=Al, Ga), exhibit a close contact between the coordinatively unsaturated Al or Ga atoms and the α-C atoms of the intact ethynyl groups. These interactions activate the Ge-C(alkynyl) bonds and favour the thermally induced insertion of these C atoms into the E-C(vinyl) bonds by means of 1,1-carbalumination or 1,1-carbagallation reactions. For the first time the latter method was shown to be a powerful alternative to known metallation processes.

Selective P4 activation by an organometallic nickel(I) radical: formation of a dinuclear nickel(II) tetraphosphide and related di- and trichalcogenides.

The reaction of the 17e nickel(I) radical [CpNi(IDipp)] (1, IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with P4 results in a nickel tetraphosphide [{CpNi(IDipp)}2(μ-η(1):η(1)-P4)] with a butterfly-P4(2-) ligand; related chalcogenides [{CpNi(IDipp)}2(μ-E2)] (E = S, Se, Te) and [{CpNi(IDipp)}2(μ-E3)] (E = S, Se) are formed with S8, Se∞ and Te∞.