An up-to-date account of the synthesis of side-on-bound dinitrogen complexes of the lanthanides, the actinides, and the transition elements over the past 40 years is given. In addition, the reactivity of these derivatives is summarized. There have been many complicated multinuclear cluster complexes with the N 2 imbedded in a fashion that corresponds to side-on N 2 . There have been some suggestions, as early as 1960, that side-on dinitrogen complexes should exist. However, a key date in this area is 1988, which is when the disamarium complex (Cp* 2 Sm) 2 (µ-η 2 :η 2 -N 2 ) was reported. It is this date that is used in this account as the real starting point for the area of side-on dinitrogen coordination chemistry. After 1988, side-on dinitrogen complexes are reviewed from the point of view of synthesis, structure (N-N bond lengths, where applicable), and reactivity. What becomes apparent is that while there have been many new side-on dinitrogen complexes discovered recently, investigations into their reactivity patterns are still at a primitive stage.
A new dinitrogen complex, deep blue-green {[NPN]*Zr(THF)}(2)(mu-eta(2):eta(2)-N(2)) ([NPN]* = {[N-(2,4,6-Me(3)C(6)H(2))(2-N-5-MeC(6)H(3))](2)PPh}), was prepared in high yield by the reduction of [NPN]*ZrCl(2) with 2.2 equiv of KC(8) in THF under N(2). The solid-state molecular structure shows that N(2) is strongly activated (N-N bond length: 1.503(6) A) and bound side-on to two Zr atoms. Coordinated THF can be readily replaced by adding pyridine (py) or PMe(2)R (R = Me, Ph) to the complex to obtain {[NPN]*Zr(py)}(2)(mu-eta(2):eta(2)-N(2)) or {[NPN]*Zr(PMe(2)R)}(mu-eta(2):eta(2)-N(2)){Zr[NPN]*} in high yield. X-ray diffraction experiments show that the N(2) moiety is strongly activated and remains side-on bound to Zr for the py and PMe(2)Ph adducts; interestingly, only one PMe(2)Ph coordinates to the Zr(2)N(2) unit. {[NPN]*Zr(PMe(2)R)}(mu-eta(2):eta(2)-N(2)){Zr[NPN]*} reacts slowly with H(2) to provide {[NPN]*Zr(PMe(2)R)}(mu-H)(mu-eta(2):eta(2)-N(2)H){Zr[NPN]*}, as determined by isotopic labeling, and multinuclear NMR spectroscopy. The THF adduct does not react with H(2) even after an extended period, whereas the pyridine adduct does undergo a reaction with H(2), but to a mixture of products.
The arene-bridged dilithium diamidophosphine ligand, [(2,4,6- Me 3 C 6 H 2 )NLi-2-(5-MeC 6 H 3 )] 2 -PPh, [NPN]*Li 2 , was prepared from (2,4,6-Me 3 C 6 H 2 )(2-Br-4-MeC 6 H 3 )NH, n BuLi, and PhPCl 2 in Et 2 O and isolated as a dioxane adduct in ∼85% yield. The solid-state structure of [NPN]-*Li 2 (THF) 2 as determined by X-ray diffraction shows both lithiums bridged by the amido nitrogens with one Li ion coordinated to the phosphine donor. The reaction of [NPN]*H 2 and Zr(NMe 2 ) 4 in toluene produced [NPN]*Zr(NMe 2 ) 2 in 90% isolated yield. Addition of excess Me 3 SiCl to [NPN]*Zr(NMe 2 ) 2 converts it to [NPN]*ZrCl 2 in high yield. The solid-state structure of [NPN]*ZrCl 2 as determined by X-ray diffraction shows the Zr center is a distorted trigonal bipyramid with the phosphine and the chloride apical. The ortho-Me's on the N-mesityl moiety are inequivalent in both the Li and Zr complexes of [NPN]* by NMR spectroscopy, while in [NPN]*H 2 MesN ortho-Me's appear as broad singlets. VT-NMR of [NPN]*H 2 indicated that ∆G rot q of MesC ipso -N is approximately 15.5 ( 0.3 kcal mol -1 . The thermally labile and light-sensitive zirconium dimethyl complex [NPN]*ZrMe 2 was prepared from [NPN]*ZrCl 2 and MeMgCl in Et 2 O in 80% yield.
Coordination chemistry Z 0150 Synthesis and Reactivity of Side-On-Bound Dinitrogen Metal Complexes -[107 refs.]. -(MACLACHLAN, E. A.; FRYZUK*, M. D.; Organometallics 25 (2006) 7, 1530-1543; Dep. Chem., Univ. British Columbia, Vancouver, B. C. V6T 1Z1, Can.; Eng.) -Mischke 28-233
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.