Synthesis and Structures of Group 11 Metal Triazenide Complexes: Ligand Supported Metallophilic Interactions

Abstract

A homologous and homoleptic series of stable Group 11 metal triazenide complexes with the general formula [M(L')](n) (M = Cu or Au, n = 2; M = Ag, n = 3) featuring the bulky triazenide ligand N,N'-bis(2,6-di-isopropylphenyl)triazene, L'H, have been prepared by the reaction of Li[L'] with the metal chlorides, CuCl, AgCl, and [(THT)AuCl], respectively, in a 1:1 stoichiometric ratio. The compounds [Cu(2)(L')(2)] and [Au(2)(L')(2)] crystallized as dimers with M...M separations of 2.4458(4) A and 2.6762(4) A, respectively. In comparison, the reaction of AgCl with Li[L'] results in the formation of the tri-silver complex [Ag(3)(L')(3)] with Ag...Ag separations of 3.01184(17) A, 2.95329(17) A, and 2.92745(16) A. Attempts to react the parent triazene system L'H with [Cu(Mes)] resulted in the formation of the novel tri-copper system [Cu(3)(L')(2)(Mes)]. In all cases the molecular structures of the resultant complexes have been unambiguously determined by single crystal X-ray diffraction experiments.

Cuprophilic Interactions in and between Molecular Entities

“…Despite their ease of synthesis and tuning of the steric demand, the reactive N‐N‐N functionality of triazenes hampered their development in coordination chemistry. Three dimeric copper(I) triazenides [Cu(μ‐κ 2 ‐N(NAr) 2 )] 2 [Ar=Ph ( 1 ), 2‐MeO 2 CC 6 H 4 ( 2 ), 2,6‐ i Pr 2 C 6 H 3 ( 3 )] were structurally analyzed (Figure ) . The observed Cu–Cu distances of 1 (2.4405(10) Å), 2 (2.4289(12) Å), and 3 (2.4458(4) Å) were almost equivalent and independent of the bulk of the ligands.…”

“…[152] Despite their ease of synthesis and tuning of the steric demand, the reactive N-N-N functionality of triazenesh ampered their developmenti nc oordinationc hemistry.T hree dimeric copper(I) triazenides [Cu(m-k 2 -N(NAr) 2 )] 2 [Ar = Ph (1), 2-MeO 2 CC 6 H 4 (2), 2,6-iPr 2 C 6 H 3 (3)] weres tructurally analyzed ( Figure 1). [123,153] The observed Cu-Cu distances of 1 (2.4405(10) ), 2 (2.4289(12) ), and 3 (2.4458(4) )w ere almoste quivalent and independento ft he bulk of the ligands. It is interesting to note that each Cu center in 2 was additionally ligatedb yo ne oxygen atom from the ester substituents, but the Cu-Cu distance was still the shortesta mong this family.…”

“…Recognition of the [{Cu(NH 3 ) 2 } 2 ] 2 + species in a supramolecular cavity allows studying weak cuprophilic interactions systematically at both the ground and excited states by the time-resolved diffraction techniques. [181,182] Unsupported cuprophilic interactions were observed in the solid states of [Cu(NH 3 )Cl] (122)a nd [Cu(NH 3 ) 2 ]Br (123). [183] Compounds 122 and 123 were prepared from reaction mixtures of CuX 2 (X = Cl, Br) and lithium bis(trimethylsilyl)amide with 1,4-naphthohydroquinone.…”

Synthesis and Structures of Dinuclear Copper(I) and Silver(I) 1, 3‐Bis[(2‐chloro)benzene]triazenide Complexes

“…The Cu–N and Ag–N bond lengths in both [Cu 2 (L) 2 ] and [Ag 2 (L) 2 ] are within the expected ranges for terminal M (I)–N bonds [Cu–N: 1.8966(16) Å and 1.8983(16) Å; Ag–N: 2.1666(18) Å and 2.1722(18) Å] 2,12,18. Similarly the N–N bond lengths within the triazenide ligands {N(1)–N(2): 1.302(2) Å, N(2)–N(3): 1.301(2) Å in [Cu 2 (L) 2 ] and N(1)–N(2): 1.302(3) Å, N(2)–N(3): 1.294(3) Å in [Ag 2 (L) 2 ]}are also comparable to those observed in related systems 12,18. A significant point of interest in these dimeric Cu I and Ag I complexes is the presence of relatively short M ··· M intramolecular distances.…”

“…This versatile ligand has been employed in the synthesis of complexes of transition metals4–9 and main group elements 10,11. Additionally, triazenide ligands can stabilize late transition metal complexes showing only close metal–metal interaction12 or containing metal–metal bonds 13. In our previous work, we have prepared some polynuclear complexes with triazenide ligands 14–16.…”