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 (μ-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, P21/c, a =
11.751(1) Å, b = 11.376(1) Å, c = 15.562(2) Å, β = 103.584(2)°, V = 2022.0(4) Å3, Z = 4. 2:  monoclinic,
P21/c, a = 11.896(1) Å, b = 11.396(1) Å, c = 15.655(1) Å, β = 104.474(2)°, V = 2054.9(3) Å3, Z = 4. 3:
triclinic, P1̄, a = 11.541(2) Å, b = 12.119(2) Å, c = 13.199(2) Å, α = 80.377(2)°, β = 76.204(3)°, γ = 66.826(2)°, V = 1642.5(4) Å3, Z = 2. Crystals of 4 crystallized from acetone:  triclinic, P1̄, a = 11.586(5) Å, b =
12.144(5) Å, c = 13.364(6) Å, α = 80.599(7)°, β = 76.271(8)°, γ = 67.158(8)°, V = 1678.0(12) Å3, Z = 2.
Crystals of 4‘ are obtained from CH2Cl2−pentane solution:  monoclinic, C2/c, a = 17.555(4) Å, b = 15.277(3)
Å, c = 13.093(3) Å, β = 111.179(3)°, V = 3274.0(12) Å3, Z = 4. By contrast, similar reactions in the presence
of methanol yielded complexes with the composition [μ-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) Å, b = 16.602(1) Å, c = 14.641(1) Å, β = 116.147(1)°,
V = 5880.5(8) Å3, Z = 8. 6:  monoclinic, C2/c, a = 27.513(3) Å, b = 16.740(2) Å, c = 14.837(2) Å, β =
116.925(2)°, V = 6092.8(10) Å3, Z = 8. An 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 [μ-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, P21/n, a = 12.114(1) Å, b = 14.878(1) Å,
c = 15.807(1) Å, β = 104.601(1)°, V = 2756.9(3) Å3, Z = 4.