Synthesis and characterization by diffraction and P-31- and Se-77-NMR spectroscopy of [Mo-3(mu(3)-Se) (mu(2)-Se-2)(3){N(SePPh2)(3)}(3)] Br and [Mo-3(mu(3)-Se) (mu(2)-Se-2)(3){Se2P(OCH2CH3)(2)}(3)] Br

The new Mo/Se clusters [Mo-3(mu(3)-Se)(mu(3)-Se-2)(3){N(SePPh3)(2)}(3)]Br ( 1) and [Mo-3(mu(3)-Se)(mu(2)-Se-2)(3){Se2P(OCH2CH3)2}(3)]Br (2) have been s ynthesized by the selective substitution of the bromo ligands in the starti ng material [PPh4](2)[Mo-3(mu(3)-Se)(mu(2)-Se-2)(3)Br-6] with the selenoorg ano bidentate ligands [N(SePPh2)(2)](-) and [Se2P(OEt)(2)](-). The complexe s have been characterized in solution by (31)p- and Se-77-NMR spectroscopy and in the solid state by single crystal X-ray diffraction; the same cation structures are present both in solution and in the solid state. Crystallog raphic data for 1: [Mo-3(mu(3)-Se)(mu(2)-Se-2)(3){N(SePPh2)2}(3)]Br- 3 CH2C l2, C(72)H(60)BrMo(3)N(3)P(6)Se(13 .)3 CH2Cl2, trigonal, space group R-3, a = 21.299 (10) Angstrom, c = 38.433 (27) Angstrom, V = 15 100 (15) Angstrom (3) T = -120 degrees C, Z = 6; crystallographic data for 2:[Mo-3(mu(3)-Se)( mu(2)-Se-2)(3){Se2P(OCH2CH3)(2)}(3)]Br, C12H30BrMo3P3O3Se13, monoclinic, sp ace group P2(1)/n, a = 13.404 (2) Angstrom, b = 22.732 (4) Angstrom, c = 13 .932 (3) Angstrom, beta = 113.134 (3)degrees, V = 3303.7(12) Angstrom(3), T = -120 degrees C, Z = 4. (C) 2000 Academie des sciences / Editions scienti ques et medicales Elsevier SAS.