Binuclear Cu(I) and Mn(0) Complexes with a Tridentate Pyridine‐NHC‐Phosphane Ligand in a µ‐κ²Ĉ,N‐M;κ¹P‐M Coordination Mode

Abstract

The reaction of a non-symmetrical pyridine-NHCphosphane (NĈP) ligand -generated in situ upon the deprotonation of the corresponding imidazolium salt -with equimolar amount of [Cu(NCMe) 4 ](BF 4 ) or Mn 2 (CO) 10 leads to the formation of bimetallic complexes [Cu 2 (NĈP) 2 (NCMe)](BF 4 ) 2 and [Mn 2 (CO) 7 (NĈP)], respectively, in which the tridentate ligand ex- [a] 4358 hibits an unusual μ-κ 2 Ĉ,N-M;κ 1 P-M coordination mode. According to NMR spectroscopy and mass spectrometry, the binuclear copper complex is in equilibrium in MeCN solution with two mononuclear species, namely [Cu(κ 2 Ĉ,P-NĈP) 2 ](BF 4 ) and [Cu(κ 3 -N,Ĉ,P-NĈP)(NCMe)](BF 4 ). Scheme 1. Diverse coordination modes of tridentate ligands in transition metal complexes.

Cationic PCP and PCN NHC Core Pincer-Type Mn(I) Complexes: From Synthesis to Catalysis

“…29 As general trend, the Mn−NHC bond distances are significantly shortened in the tridentate systems compared to their bidentate precursors, a difference that may be attributed to the more constrained geometries and the cationic nature of the pincer-type complexes. It is noteworthy, that the Mncarbene bond in pincer complex [15](OTf) (1.9360(16) Å) is significantly shorter than that observed in binuclear [Mn2(CO)7(PCN)] complex bearing structurally close tridentate PCN ligand in the bridging μ-κ 2 C,N-M;κ 1 P-M-coordination mode (1.9700( 17) Å) 30 and indeed represents one of the shortest distance known to date for manganese imidazol-2-ylidene complexes. 31 Since a similar trend was previously observed for re-lated Ni(II) complex, 4d it may be assumed that the rigid character of such PCN ligands forming two five-membered metallacycles is particularly favorable to strengthen metal-NHC bonding.…”

Recent progress on NHC-stabilized early transition metal (group 3–7) complexes: Synthesis and applications

“…Valyaev and coll. synthesized the non-symmetrical pyridine-NHC-phosphane ligand 159 and investigated its coordination chemistry with Mn(0) (Scheme 43) 153. It was reacted with Mn2(CO)10 under UV irradiation and the corresponding dinuclear Mn complex 160 was isolated in moderate yield.…”

Manganese‐Mediated Synthesis of NHC‐Phosphine Ligand Precursors

“…Neutral alumina (Brockmann type III (4.7 % water), 50–200 μm) obtained from Acros Organics was used for the synthesis of complex 6 . N ‐mesitylimidazole, [62] N ‐2,6‐diisopropylphenylimidazole, [63] N ‐1‐adamantylimidazole, [64] N ‐(2‐pyridyl)imidazole, [65] N ‐[(methylthio)methyl]imidazole, [66] 3‐((1 H ‐imidazol‐1‐yl)methyl)‐1‐methyl‐1 H ‐imidazolium iodide, [67] rac ‐ trans ‐2,5‐diphenylphospholane [51,52] as well as Mn(I) complexes [ 1 R ](BF 4 ) [44] and 3 [50] were prepared according to previously described procedures. All other reagent‐grade chemicals were purchased from commercial sources and used as received.…”