Syntheses, structures, FAB mass spectra, and magnetic properties of chromium chalcogenide cluster complexes [Cr6Se8(PEt3)(6)], [Cr6Se8(H)(PEt3)(6)], and [Cr6S8(H)(PEt3)(6)]
S. Kamiguchi et al., Syntheses, structures, FAB mass spectra, and magnetic properties of chromium chalcogenide cluster complexes [Cr6Se8(PEt3)(6)], [Cr6Se8(H)(PEt3)(6)], and [Cr6S8(H)(PEt3)(6)], INORG CHEM, 37(26), 1998, pp. 6852-6857
Chromium selenide cluster complexes [Cr6Se8(PEt3)(6)] (1) and [Cr6Se8(H)(PE
t3)(6)] (2) were prepared by the reaction of anhydrous chromium dichloride,
Na2Sex, and triethylphosphine in methanol. A similar procedure except for
the use of NaSxH in place of Na2Sex gave a sulfide cluster complex [Cr6S8(H
)(PEt3)(6)] (3) The partly deuterated derivative [Cr6S8(D)(0.8)(H)(0.2)(PEt
3)(6)] (4) was prepared for comparison. An extra hydrogen atom in 2-4 has b
een confirmed by FAB mass spectra. The reactivity and structural studies ha
ve indicated that it is at the center of the Cr-6 octahedral cluster. The m
olecular structures of 1 and 2 have been determined by X-ray structure anal
yses. Crystallographic data: [Cr6Se8(PEt3)(6)] (1) (226 K), triclinic, P (1
) over bar, a = 12.887(2) Angstrom, b = 25.332(7) Angstrom, c = 12.061(3) A
ngstrom, alpha = 111.23(2)degrees, beta = 108.25(2)degrees, gamma = 109.86(
2)degrees, Z = 2; [Cr6Se8(H)(PEt3)(6)]. 2THF (2) (293 K), rhombohedral, R (
3) over bar, a = 17.384(4) Angstrom, c = 19.768(4) Angstrom, Z = 3. The Cr-
Cr bond distances of 2 are 0.13-0.16 Angstrom shorter than those of 1, indi
cative of bonding interaction between the insterstitial hydrogen and the si
x chromium atoms in 2. The number of cluster valence electrons for 1 is 20
while that for 2 and 3 is 21. Magnetic measurements (2-330 K for 1, 2.5-330
K for 2, and 4.5-330 K for 3) have shown that the number of unpaired spins
in the ground state for 1 is zero while that for 2 and 3 is one.