Ruth A. Bartlett

Isolation and X-ray crystal structures of the organolithium etherate complexes, [Li(Et2O)2(CPh3)] and [{Li(Et2O)(2,4,6-(CHMe2)3C6H2)}2]

Abstract The organolithium etherate complexes [Li(Et 2 O) 2 (CPh 3 )] ( 1 ) and [{Li(Et 2 O)(2,4,6-(CHMe 2 ) 3 C 6 H 2 )} 2 ] ( 2 ) have been crystallized from their ether solutions and structurally characterized by X-ray crystallography. The complex 1 has the rare mononuclear structure, with lithium coordinated to two ethers and at least three carbon atoms of the CPh 3 group; it thus offers an interesting comparison to the structure of [Li(12-crown-4) 2 ][CPh 3 ], which contains a free [CPh 3 ] − ion. The structure of complex 2 is dimeric, and features two lithium atoms bridging between two 2,4,6-(CHMe 2 ) 3 C 6 H 2 (Trip) groups. The lithium atoms are three-coordinate, being bonded to diethyl ether in addition to two carbon atoms. A significant feature of this structure is the asymmetric nature of the lithium bridging, with significant distortion in the angles and distances surrounding lithium being apparent. This is suggestive of the weak association due to the large size of the Trip group. These structures represent rare additions to the small number of known structures involving organolithium compounds solvated by commonly used monodentate ether solvents.

Synthesis and structural characterisation of the first neutral homoleptic lanthanide metal(III) alkyls: [LnR3][Ln = La or Sm, R = CH(SiMe3)2]

The alkylating agent LiR [R = CH(SiMe3)2] reacts with [Ln(OC6H3But2-2,6)3](Ln = La or Sm) under ambient conditions to yield [LnR3][Ln = La (1) or Sm (2)], the first structurally characterised neutral homoleptic alkyls of the lanthanide metals; the crystalline compounds (1) and (2) have C3 symmetry and almost tetrahedral CLnC′ angles, with Ln–C bonds of 2.515(9)(1) or 2.33(2)A(2), and unusually short Ln ⋯ CH3 contacts [3.121(9)(1) or 2.85(3)A(2)].

The synthesis and characterization of the vanadium diphosphene complex trans-[{V(η5-C5H5)(CO)3}2(PMes)2]

Abstract The vanadium diphosphene complex trans-[{V(η5-C5H5)(CO)3}2(PMes)2] (1) has been synthesized and characterized by X-ray crystallography, 31P NMR and IR spectroscopy. It is the first reported example of a Group 5 transition-metal diphosphene complex. Complex 1 was synthesized as blue-green crystals via the reaction of Na2V(η5-C5H5)(CO)3 and PCl2Mes and purified by chromatography. It has a centrosymmetric trans structure with a planar C(9)VPP′V′C(9)′ core. The PP′ distance is 2.052(2) A and the VP distance is 2.397(1) A. The structure is discussed in the context of other diphosphene complexes. On the basis of both the structural and IR data of these and the related iron and chromium diphosphene and phosphane complexes it was concluded that a diphosphene bound in an end-on fashion has a π acceptor/σ-donor ratio similar to, or marginally better than, triarylphosphanes. Although calculations indicate considerable metalphosphorus back bonding it receives only equivocal support from experimental data.

The first X-ray crystal structural characterizations of alkali metal alkyl thiolates: X-ray crystal structures of [Li2(thf)4{SCH(SiMe3)2}2] and [Li2(thf)3.5{SC(SiMe3)3}2](thf = tetrahydrofuran)

The isolation and X-ray structural characterization of [Li2(thf)4{SCH(SiMe3)2}2](1) and [Li2(thf)3.5{SC(SiMe3)3}2](2)(thf = tetrahydrofuran) show them to be dimers with a central Li2S2 core (Li–S distances average 2.43 A); the lithium atoms have approximately tetrahedral co-ordination and each sulphur is three-co-ordinate, being pyramidal in (1) and almost planar in (2) where severe crowding is evident.

Structural Characterization of the Solvate Complexes of the Lithium Salts of Diorganophosphides and Phosphinideneborates; A Pathway to Phosphorus-Boron Double Bonds

Abstract The structures of several solvated lithium diorganophosphides are described. These may take a variety of structures including chain-like polymers with alternating Li+ and PR2 − groups, dimeric species with PR2 − groups bridging two Li+ ions or mononuclear species having terminal −PR2 groups which have pyramidal geometries at phosphorus. The Li+ ions in all structures are solvated by either THF or Et2O bases. Separation of the Li+ can be effected using 12-crown-4 to coordinate Li+ as [Li(12-crown-4)2]+ affording free [PR2]− counterions. An extension of these techniques has led to the synthesis of the first compounds which have B-P double bonds. These are the compounds [Li(Et2O)2PRBMes2] and [Li(12-crown-4)2][PRBMes2](R=Ph, C6H11,Mes) which have B-P bond lengths of 1.82 – 1.83A.

A closed paramagnetic electron-precise cluster

A pentametallic cluster is formed by addition of two [SnR2][R = CH(SiMe3)2] groups to [Os3(CO)8(µ-H)(C6H4PhPCH2PPh2)], in a reaction reversing the ortho-hydrogen abstraction and giving the first closed electron-precise paramagnetic cluster.