Bifunctional chelates with mixed aromatic and aliphatic amine donors for labeling of biomolecules with the {Tc(CO)3}+ and {Re(CO)3}+ cores

A series of tridentate ligands consisting of mixed aromatic and aliphatic amine derivatives of single amino acid chelates and phenylpiperazine have been developed, and their reactions with [NEt4]2[ReBr3(CO)3] have been investigated. The compounds [Re(CO)3{(NC5H4CH2)NCH3(C2H4)NHCH3}]Br (4), [Re(CO)3{(NC5H4CH2)NCH3(C2H4)NCH3(CH2)xCOOC2H5}]Br (x = 1, 5; x = 4, 6) [Re(CO)3{(NC5H4CH2)NH(C2H4)N(CH3)2}]Br (7), [Re(CO)3{(NC5H4CH2)N(CH 2COOC2H5)(C2H4)N(CH3)2}]Br (8) and [Re(CO)3(NC5H4CH2)(C2H4NH2)N(CH2)3–CH3Ophenpip]Br (9) (phenpip: phenylpiperazine, –C6H4–(CH2CH2)2N–) were prepared and characterized by elemental analysis, NMR, IR, HSMS and X-ray crystallography. All complexes exhibit fac-{Re(CO)3N3} coordination geometry in the cationic molecular unit. Crystal data for C13H17BrN3O3Re (4): orthorhombic, Pbca, a = 13.4510(8) Å, b = 10.5728(6) Å, c = 22.5378(13) Å, V = 3205.2(3) Å3, Z = 8; C17H23BrN3O5Re (5): orthorhombic, Pcca, a = 16.5907(7) Å,b = 14.8387(6) Å, c = 16.7075(7) Å, V = 4113.1(3) Å3, Z = 8; C13H25BrN3O7Re (7 · 4H2O): monoclinic, P21/n, a = 14.0698(17) Å, b = 9.6760(12) Å, c = 15.6099 (19) Å, β = 114.930(2)°, V = 1927.1(4) Å3, Z = 4; C17H23BrN3O5Re (8): monoclinic, P21/n, a = 7.5312(5) Å, b = 16.0366(10) Å, c = 16.8741(10) Å, β = 98.9990(10)°, V = 2012.9(2) Å3, Z = 4.

The chemistry of the {Re(I)(CO)3}+1 core with a series of tridentate ligands of the single amino acid chelate (SAAC) family, bearing mixed aliphatic and aromatic organonitrogen substituents has been investigated. The structure of the representative example [Re(CO)3{(NC5H4CH2)NCH3(C2H4)NCH3(CH2)xCOOC2H5}]Br is shown below.Figure optionsDownload as PowerPoint slide