Andrew J. Peel

Structural Effects in Lithiocuprate Chemistry: The Elucidation of Reactive Pentametallic Complexes

TMPLi (TMP=2,2,6,6-tetramethylpiperidide) reacts with CuI salts in the presence of Et2O to give the dimers [{(TMP)2Cu(X)Li2(OEt2)}2] (X=CN, halide). In contrast, the use of DMPLi (DMP=cis-2,6-dimethylpiperidide) gives an unprecedented structural motif; [{(DMP)2CuLi(OEt2)}2LiX] (X=halide). This formulation suggests a hitherto unexplored route to the in situ formation of Gilman-type bases that are of proven reactivity in directed ortho cupration.

Towards the Synthesis of Guanidinate- and Amidinate-Bridged Dimers of Mn and Ni

Reactions of Cp2M (Cp = cyclopentadienyl, M = Mn, Ni) with lithium amidinates and guanidinates are reported. The highly oxophilic nature of Mn leads to the isolation of the interstitial oxide Mn4O(MeN···CH···NMe)6 (4) in preference to the intended paddle-wheel homodimer Mn2(MeN···CH···NMe)4 when employing the sterically uncongested amidinate [MeN···CH···NMe]– ligand. In contrast, an analogous reaction using Cp2Ni yielded Ni2(MeN···CH···NMe)4 (5). The use of monoprotic guanidinate ligands also gave contrasting results for Mn and Ni. In the first case, the highly unusual spirocycle Mn{μ-NC(NMe2)2}4Li2·3THF (6) was produced in low yield. For M = Ni, use of the [hpp]– (1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate) ligand gives results comparable with the synthesis of 5, with Ni2(hpp)4 (7) isolated. In contrast to recent data obtained using Cp2Cr, the guanidinate ligands do not sequester coformed CpLi. Density functional theory analysis corroborates the view that the intermetal distance in each of the reported dinickel paddle-wheel complexes (2.4846(8) and 2.3753(5) A in 5 and 7 respectively) is defined by the geometric parameters of the bidentate ligands and that intermetal bonding is not present.

Research data supporting "Metal exchange in lithiocuprates: implications for our understanding of structure and reactivity"

Crystallographic and multinuclear NMR spectroscopic data for a series of lithium cyanatocuprate compounds prepared and analyzed at Cambridge (UK) in 2015-2017.

Chapter 6:Alkali/Coinage metals – organolithium, organocuprate chemistry

This chapter covers the literature on group 1 and 11 organometallics, primarily those that contain a carbon-metal bond, in the years 2011 and 2012. In the first part, coordination compounds of the alkali metals are discussed. We look firstly at organolithiums and then cover compounds of the higher alkali metals. Sandwich compounds are discussed, including significant new work that relates to lithium-coordinated reduced corannulene systems. The use of other aryl ligands, as well as alkyl, alkynyl, carbenoid and N-donor ligands is also discussed. Compounds of the coinage metals - copper, silver and gold - are considered in the second part of the review. Discussion is broken down by metal, starting with copper. The first efficient synthesis of (Ph3P)3CuCF3 is reported, as are related studies on “CuCF3” derivatives. Other copper systems to have been looked at in 2011/12 include those with aryl, phosphorus- and sulfur-donor ligands. A large number of studies on carbenoid complexes are also reviewed. This interest in carbene chemistry is also reflected within the silver and gold sections that follow, with alkynyl ligand chemistry also playing a major role in recent gold studies. For both groups 1 and 11, mixed-metal systems are also discussed as appropriate, including the development of synergic bases, new multiply-bonded transition metal complexes and luminescent group 11 clusters.