A Two-Coordinate Manganese(0) Complex with an Unsupported Mn–Mg Bond: Allowing Access to Low Coordinate Homo- and Heterobimetallic Compounds

Abstract

This study details the synthesis and characterization of an unprecedented two-coordinate, high-spin manganese(0) complex that incorporates an unsupported Mn-Mg bond, viz. L(†)MnMg((Mes)Nacnac) (L(†) = -N(Ar(†))(SiPr(i)3), Ar(†) = C6H2{C(H)Ph2}2Pr(i)-2,6,4; (Mes)Nacnac = [(MesNCMe)2CH](-); Mes = mesityl). This compound has been utilized as an "inorganic Grignard reagent" in the preparation of the first two-coordinate manganese(I) dimer, L(†)MnMnL* (L* = -N(Ar*)(SiMe3), Ar* = C6H2{C(H)Ph2}2Me-2,6,4), and the related mixed valence, bis(amido)-hetereobimetallic complex, Mn(II)(μ-L(†))(μ-L*)Cr(0). It is also shown to act as a two-electron reducing agent in reactions with unsaturated substrates.

Systematic Expansion of Active Spaces beyond the CASSCF Limit: A GASSCF/SplitGAS Benchmark Study

“…The 1 1 A 1 ground state has a multireference character, with the valence electronic structure of the dominant configuration (83%) being ( 2 σ ) 2 ( 2 n σ ) 2 ( 3 n σ ) 2 ( 4 n σ ) 2 ( π ) 2 ( n π ) 2 o r (3b 2 ) 2 (5a 1 ) 2 (6a 1 ) 2 (4b 2 ) 2 (1b 1 ) 2 (1a 2 ) 2 . In CAS (18,12), the 1σ (3a 1 ), 1σ* (4a 1 ), and 1n σ (2b 2 ) MOs (mostly linear combination of 2s AOs) have also been correlated.…”

“…Two CAS choices were considered: CAS (12,9) and CAS- (18,12). CAS (12,9) is composed of the nine MOs containing the 2p x , 2p y , and 2p z AOs.…”

“…CAS (12,9) is composed of the nine MOs containing the 2p x , 2p y , and 2p z AOs. The 1 1 A 1 ground state has a multireference character, with the valence electronic structure of the dominant configuration (83%) being ( 2 σ ) 2 ( 2 n σ ) 2 ( 3 n σ ) 2 ( 4 n σ ) 2 ( π ) 2 ( n π ) 2 o r (3b 2 ) 2 (5a 1 ) 2 (6a 1 ) 2 (4b 2 ) 2 (1b 1 ) 2 (1a 2 ) 2 .…”

A monomeric, heterobimetallic complex with an unsupported Mg–Fe bond

“…4 For unsupported bonds between a transition metal and an element from elsewhere in the periodic table, much recent progress has been made in the p-block, 5 lanthanides 6 and actinides, 4,7 which is facilitating the systematic study of the nature of the bonding between these elements. There is, however, a paucity of analogous complexes of the s-block elements, and it is only in the last few years that the number of compounds with direct, unsupported bonds between an alkaline earth (Ae) metal and a transition metal (TM) has started to gather pace in the literature, [8][9][10][11][12][13][14][15][16][17] and complexes featuring a Be−TM bond 11,16 and a Ca−TM bond 12 are incredibly scarce. The expansion of the scope of complexes featuring an unsupported bond between an alkaline earth and transition metal will aid the understanding of the fundamental structure and bonding within this family of heterobimetallic compounds.…”

“…The structure was solved via direct methods and refined by fullmatrix least-squares in SHELXL-97. 22 Positional disorder was identified for atoms C(33), C(35), C(36) and C (37): the occupancies of the two components were refined competitively, converging at a ratio of 0.704 (14):0.296 (14). Extensive restraints were applied to the anisotropic displacement parameters in the affected region.…”