Syntheses, Structures, and Reactivities of 2,3-Pyrazyl-Linked Bis(1-aza-allyl) Alkali-Metal Complexes

Abstract

The dilithium compound [Li2{{N(SiMe3)C(Bu t )C(H)}2C4H2N2-2,3}(THF)2]2 (2) has been obtained by dilithiation of 2,3-bis(trimethylsilylmethyl)pyrazine, (CH2SiMe3)2C4H2N2-2,3 (1), using Bu n Li followed by the reaction with Bu t CN. Compounds of the heavier congeners [Na2{{N(SiMe3)C(Bu t )C(H)}2C4H2N2-2,3}(THF)2]2 (3) and [K2{{N(SiMe3)C(Bu t )C(H)}2C4H2N2-2,3}(THF)3]2 (4) have been obtained by treating 2 with Bu t ONa or Bu t OK, respectively. Treatment of 2 with 4 equiv of MgBr2(Et2O) yielded the binuclear magnesium complex [Mg2{{N(SiMe3)C(Bu t )C(H)}2C4H2N2-2,3}Br2(THF)4] (5). Similar metathesis reaction of 2 with 4 equiv of ZnCl2 gave the zwitterionic lithium zincate complex [Zn2{{N(SiMe3)C(Bu t )C(H)}2C4H2N2-2,3}Cl2(μ-Cl)2Li2(THF)6] (6). However, the reaction of 2 with 4 equiv of CdCl2 afforded a heterocyclic compound, (7). X-ray structures of compounds 2−7 have been determined.

A Novel Bulky Heteroaromatic‐Substituted Methanide Mimicking NacNac: Bis(4,6‐tert‐butylbenzoxazol‐2‐yl)methanide in s‐Block Metal Coordination

“…Relative to the structures of 4 and 6 the N‐M‐N bite angle in 5 is strongly reduced to realize the favored η 5 coordination of the soft potassium ion to the soft, undirected π density of the deprotonated ligand molecules . Nevertheless, the average dislocation of the metal ions from the C 3 N 2 plane (2.311(7) Å) and the average N‐M‐N bite angle (65.99(2)°) are in good agreement with the values found for a related dimeric NacNac‐derived complex with an average C 3 N 2 plane distance of 2.29(1) Å and mean bite angle of 65.7(2)° . In contrast, the dislocation found in 5 falls at the short end of the range for other non‐NacNac related compounds that display potassium–π‐system interactions.…”

“…Complex 6 is the first example of a NacNac‐related bis(benzoxazol‐2‐yl)methanide magnesium complex with a trigonal bipyramidal geometry. Comparable trigonal bipyramidal NacNac‐based magnesium complexes, such as the dinuclear [Mg 2 ({N(SiMe 3 )C( t Bu)C(H)} 2 {2,3‐C 4 H 2 N 2 })Br 2 (THF) 4 ] and the tripodal species [({ κ 3 ‐N,N’,O‐(DippNCMe) 2 (OCCPh 2 )CH}Mg{ μ ‐I}) 2 ] and [({ κ 3 ‐N,N’,O‐(DepNCMe) 2 (OCCPh 2 )CH}Mg) 2 ( μ ‐ κ 2 : κ 2 ‐S 2 O 4 )] (Dep=2,6‐diethylphenyl), exhibit values from 2.155–2.132 Å, thus have slightly shorter Mg−N bonds than in 6 . Interestingly, in the six‐coordinate complex [Mg{(pz*) 3 C} 2 ] (pz*=3,5‐dimethylpyrazolyl), the Mg−N bond length is only slightly longer (2.197 Å) than in 6 …”

“…[42,43] Nevertheless, the average dislocation of the metal ions from the C 3 N 2 plane (2.311 (7) ) and the average N-M-N bite angle (65.99(2)8)a re in good agreement with the values found forar elated dimericN acNacderived complex with an average C 3 N 2 plane distance of 2.29(1) and mean bite angle of 65.7(2)8. [44] In contrast, the dislocation found in 5 falls at the short end of the range for other non-NacNac relatedc ompounds that display potassiump-systemi nteractions. For example, the h 6 -a nd h 5 -bound species [K(PhCH 2 )(PMDETA)] 1 [45] and[ K(C 5 Me 5 )·2 Py] 1 [46] (PMDETA = (Me 2 NCH 2 CH 2 ) 2 NMe), Py = pyridyl) also adopt ap olymerics tructure in the solids tate but have significantly longer potassiump-plane distances (3.150(2) and 2.79(1) ,respectively).…”

Cycloaddition of isoselenocyanates to sodium and magnesium metallacycles

“…57 The geometry of the Na(1)N(1)H(1) fragment in complex 2 is in good agreement with the previously published sodium complexes with various N–H ligands. 58–60…”

Synthesis, Insertion Reactivity, and Transmetalation Reactions of the Lithium Complex [{2‐(6‐R‐Pyr)(Me3Si)}CHLi·OEt2]2 (R = H or Me)

“…[4] Recently, Leung et al have reported the synthesis and the structures of the 2,6-pyridyl-linked bis(1-azaallyl) and 2,3-pyrazyl-linked bis(1-azaallyl)alkalimetal compounds. [7,8] Furthermore, a series of derived pyridyl-1-azaallyl low-valent group 14 compounds were described. [9,10] The synthesis of [MCl 2 {N(SiMe 3 )-C(Ph)C-(H)(C 9 H 6 N-2)}] (M = Hf and Zr) from the reaction of MCl 4 with the quinolyl-1-azaallyllithium complex [Li{N-(SiMe 3 )C(Ph)C(H)(C 9 H 6 N-2)}] 2 was reported previously, [11] as well as the synthesis of Pd complexes containing the 1-azaallyl ligand of [{[N(R)C(tBu)CH] 2 C 5 H 3 N-2,6}{Li 2 (tmen)}] and [{[N(R)C(Ph)CH] 2 C 5 H 3 N-2,6}{Li-(tmen) 2 }].…”