Synthesis and Characterization of Organohydrazino Complexes of Technetium, Rhenium, and Molybdenum with the {M(η1-HxNNR)(η2-HyNNR)} Core and Their Relationship to Radiolabeled Organohydrazine-Derivatized Chemotactic Peptides with Diagnostic Applications

The reduction of perrhenate, molybdate and pertechnetate with 2-hydrazinopyridine dihydrochloride in methanol has led to the preparation of a class of complexes containing the {M(eta(1)-NNC(5)H(4)NH(x)())(eta(2)-HNNH(y)()C(5)H(4)N)} core, represented by [TcCl(3)(NNC(5)H(4)NH)(HNNC(5)H(4)N)] (2), [ReCl(3)(NNC(5)H(4)NH)(HNNC(5)H(4)N)] (3), and [MoCl(3)(NNC(5)H(4)NH)(HNNHC(5)H(4)N)] (6). The reaction of 3 with NEt(3) results in the formation of [HNEt(3)][[ReCl(3)(NNC(5)H(4)N)(HNNC(5)H(4)N)].H(2)O (4) by deprotonation of the pyridine nitrogen site. Similarly, the reduction of perrhenate with 2-hydrazino-2-imidazoline hydrobromide has led to the preparation of the analogous [ReCl(3)(NNC(3)H(4)N(2)H)(HNNHC(3)H(4)N(2)H)] (5). Reaction of 3 with pyridine-2-thiol and pyrimidine-2-thiol yields two structurally characterized derivatives with a modified {Re(eta(1)-NNC(5)H(4)N)(eta(2)-HNNC(5)H(4)N)} core, [Re(C(5)H(4)NS)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (8) and [Re(C(4)H(3)N(2)S)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (9), respectively. Reaction of 6 with pyrimidine-2-thiol led to the isolation of the analogous [Mo(C(4)H(3)N(2)S)(2)(NNC(5)H(4)N)(HNNHC(5)H(4)N)] (11) and the seven-coordinate monohydrazine core complex [Mo(C(4)H(3)N(2)S)(3)(NNC(5)H(4)N)].CH(2)Cl(2) (12). In similar fashion, the reaction of 2 with pyridine-2-thiol yielded a complex structurally analogous to 8, [Tc(C(5)H(4)NS)(2)(NNC(5)H(4)N)(HNNC(5)H(4)N)] (7). Crystal data for 3, C(10)H(10)Cl(3)N(6)Re: triclinic, Po, a = 7.527(2) A, b = 7.599(2) A, c = 13.118(3) A, alpha = 106.55(3) degrees, beta = 90.28(3) degrees, gamma = 93.83(3) degrees, V = 717.4(4) A(3), Z = 2. For 4, C(16)H(27)Cl(3)N(7)ORe: orthorhombic, P2(1)2(1)2(1), a = 7.503(2) A, b = 10.3643(2) A, c = 30.1590(5) A, V = 2345.20(6) A(3), Z = 2. For 5, C(6)H(12)Cl(3)N(8)Re: monoclinic, P2(1)/n, a = 9.093(2) A, b = 11.105(2) A, c = 14.295(3) A, beta = 94.71(3) degrees, V = 1438.6(7) A(3), Z = 4. For 6, C(10)H(11)Cl(3)N(6)Mo: monoclinic, P2(1)/c, a = 15.366(3) A, b = 7.804(2) A, c = 12.378(3) A, beta = 95.92(3) degrees, V = 1476.4(5) A(3), Z = 4. For 7, C(20)H(17)N(8)S(2)Tc: monoclinic, P2(1), a = 8.827(2) A, b = 9.278(2) A, c = 13.304(3) A, beta = 98.92(3) degrees, V = 1076.5(5) A(3), Z = 2, 2564 reflections. For 8, C(20)H(17)N(8)S(2)Re: monoclinic, P2(1), a = 8.848(2) A, b = 9.190(2) A, c = 13.293(3) A, beta = 98.89(3) degrees, V = 1067.9(5) A(3), Z = 2. For 9, C(18)H(15)N(10)S(2)Re: monoclinic, P2(1), a = 8.796(2) A, b = 9.008(2) A, c = 13.208(3) A, beta = 97.90(3) degrees, V = 1036.6(5) A(3), Z = 2. For 12, C(18)H(15)N(9)S(3)Cl(2)Mo: monoclinic, P2(1)/n, a = 10.52900(10) A, b = 15.1116(3) A, c = 15.8193(3) A, beta = 108.4790(10) degrees, V = 2387.23(7) A(3), Z = 4. Complexes 2 and 3 serve as models for the binding of Tc(V)-oxo and Re(V)-oxo species to hydrazinonicotinamide (HYNIC)-conjugated chemotactic peptides. Furthermore, since the use of the pyrimidinethiol coligand in the {(99m)Tc-HYNIC-peptide} radiochemical species results in favorable pharmacokinetics, the thiolate derivatives 8 and 9 provide models for possible modes of interaction of metal-hydrazine cores with coligands in the radiopharmaceutical reagents.