Rhenium(I) carbonyl complexes of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPT). Rhenium(I)-promoted methoxylation of the triazine ring carbon atom in dinuclear rhenium complexes

2,4,6-Tris(2-pyridyl)- 1,3,5-triazine (TPT) bridged dinuclear rhenium(I) tricarbonyl halide complexes with the composition mu -TPT)[ReX(CO)(3)](2) (3, X = Cl; 4, X = Br) can be made either by one-pot reaction of TPT with 2 equiv of [ReX(CO)(5)] (X = Cl and Br) in chloroform or by reacting mononuclear [ReX(CO)(3)(TPT)] (2) (1, X = Cl; 2, X = Br) with an excess amount of [ReX(CO)(5)]. Crystal data are as follows. 1: monoclinic, P2(1)/c, a 11.751(1) Angstrom, b = 11.376(1) Angstrom, c = 15.562(2) Angstrom, beta = 103.584(2)degrees V = 2022.0(4) Angstrom (3), Z = 4. 2: monoclinic, P2(1)/c, a 11.896(1) Angstrom, b = 11.396(1) Angstrom, c 15.655(1) Angstrom, beta = 104.474(2)degrees; V = 2054.9(3) Angstrom (3) Z = 4. 3: triclinic, P1, a 11.541(2) Angstrom, b = 12.119(2) Angstrom, c 13.199(2) Angstrom, alpha 80.377(2)degrees P 76.204(3)degrees, gamma = 66.826(2)degrees, V = 1642.5(4) Angstrom (3), Z = 2. Crystals of 4 crystallized from acetone: triclinic, P1, a = 11.586(5) Angstrom, b = 12.144(5) Angstrom, c = 13.364(6) Angstrom, alpha = 80.599(7)degrees beta = 76-271(8)degrees, gamma = 67.158(8)degrees V= 1678.0(12) Angstrom (3), Z = 2. Crystals of 4' are obtained from CH2Cl2-pentane solution: monoclinic, C2/c, a = 17.555(4) Angstrom, b = 15.277(3) Angstrom, c = 13.093(3) Angstrom, beta = 111.179(3)degrees, V = 3274.0(12) Angstrom (3), Z = 4. By contrast, similar reactions in the presence of methanol yielded complexes with the composition [mu -C3N3(OMe)(py)(2)(pyH)] [ReX(CO)(3)](2) (5, X = Cl; 6, X = Br). Crystal data for 5: monoclinic, C2/c, a = 26.952(2) Angstrom, b = 16.602(1) Angstrom, c = 14.641(1) Angstrom, beta =116.147(1)degrees, V = 5880.5(8) Angstrom (3), Z = 8 6: monoclinic, C2/c, a = 27.513(3) W, b = 16.740(2) Angstrom, c = 14.837(2) Angstrom, beta = 116.925(2)degrees, V = 6092.8(10) Angstrom (3), Z = 8. A, Unusual metal-induced methoxylation at the carbon atom of the triazine ring of the bridging TPT ligand was observed. The nucleophilic attack of MeO- on C(3) results in a tetrahedral geometry around the carbon atom. Concomitantly, the uncoordinated pyridyl ring is protonated and rotated into a perpendicular orientation relative to the central C3N3 ring. Reaction of TPT with [NEt4](2)[ReBr3-(CO)(3)] in benzene-methanol resulted in an unexpected dinuclear complex 7, with formulation [mu -C3N3(OMe)(py)(3)][Re(CO)(3)][ReBr(CO)(3)]. The methoxylated TPT ligand functions simultaneously as a tridentate and bidentate ligand with two fac-Re(CO)(3)+ cores. Crystal data for 7: monoclinic, P2(1)/n, a = 12.114(1) Angstrom, b = 14.878(1), c = 15.807(1) Angstrom, beta = 104.601(1)degrees, V = 2756.9(3) Angstrom (3), Z = 4.