Systematic Synthesis of Di‐, Tri‐, and Tetranuclear Homo‐ and Heterometal Complexes Using a Mononuclear Copper Synthon with a Tetradentate Amino Alcohol Ligand

The reaction of Cu(NO 3 ) 2 · 3H 2 O with an N 2 O 2 tetradentate amino alcohol, N , N ‐dibenzyl‐ N′ , N′ ‐bis(2‐hydroxyethyl)ethylenediamine (H 2 L), afforded the mononuclear copper complex [Cu(H 2 L)(NO 3 )](NO 3 ) ( 1 ), which has been used to construct a series of di‐, tri‐, and tetranuclear homo‐ and heterometallic complexes. Complex 1 dimerized in the presence of NEt 3 to form the Cu 2 complex [Cu 2 (HL) 2 ](NO 3 ) 2 ( 2 ) by the deprotonation of one of the two hydroxy groups in the H 2 L ligand. The reaction of 1 with Cu(OCOH) 2 in the presence of NEt 3 afforded the Cu 3 complex [Cu 3 (HL) 2 (OCOH) 2 ](NO 3 ) 2 ( 5 ). The metalloligand {Cu(HL)} + derived from 1 reacted with M(OAc) 2 (M = Cu, Co, Zn, Ni) in the absence of NEt 3 to form the asymmetric CuM dinuclear complexes [CuM(HL)(OAc)(NO 3 ) 2 ] [M = Cu ( 3a ), Co ( 3b ), Zn ( 3c ), Ni ( 3d )], whereas in the presence of NEt 3 a unit of M(OAc) was captured by two metalloligands to give the bent CuMCu trinuclear complexes [Cu 2 M(HL) 2 (OAc) 2 (NO 3 )](NO 3 ) [M = Cu ( 4a ), Co ( 4b ), Mn ( 4c )], which were further transformed into the linear CuMCu trinuclear complexes [Cu 3 (HL) 2 {(PhO) 2 PO 2 } 2 ](NO 3 ) 2 ( 7a ) and [Cu 2 M(HL) 2 {(PhO) 2 PO 2 } 2 (MeOH) 2 ](NO 3 ) 2 [M = Co ( 7b ), Mn ( 7c )] with the aid of diphenyl phosphate bridging ligands. When (PhO)PO 2 (OH) was used as an auxiliary bridging ligand in the reaction of 1 with M(OAc) 2 and NEt 3 , the Cu 2 M 2 tetranuclear complexes [Cu 2 M 2 (HL) 2 {(PhO)PO 3 } 2 (NO 3 ) 2 ] [M = Co ( 8a ), Zn ( 8b )] were synthesized. These results demonstrate that the mononuclear copper synthon with the N 2 O 2 tetradentate amino alcohol ligand {Cu(H 2 L)} 2+ generates the quite useful metalloligand {Cu(HL)} + by the deprotonation of a hydroxy group, and subsequent reactions lead to the construction of a series of homo‐ and heterometal complexes containing Cu 2 , CuM (M = Cu, Co, Zn, Ni), bent ‐CuMCu (M = Cu, Co, Mn), linear ‐CuMCu (M = Cu, Co, Mn), and Cu 2 M 2 (M = Co, Mn) cores in a systematic and selective manner.