Heterobimetallic aggregates of copper(I) with thiotungstates and thiomolybdates. Synthesis and characterization of polymeric (NEt 4) 3[Cu 4(NCS) 5WS 4], (NEt 4) 2[(CuNCS) 3WS 4] and (NEt 4) 2[(CuNCS) 4WS 4], M = Mo, W

Abstract

Reaction of (NEt 4) 2MS 4 (M = Mo, W) with CuCl and KSCN (or NH 4SCN) in acetone or acetonitrile affords a new set of mixed metal–sulfur compounds: infinite anionic chains Cu 4(NCS) 5MS 4 3− ( 1,2), (CuNCS) 3WS 4 2− ( 3) and two dimensional polymeric dianions (CuNCS) 4MS 4 2− ( 4,5). Crystal of 1 (M = W) and 3 are triclinic, space group P1( 1: a = 10.356(2), b = 15.039(1), c = 17.356(2)Å, α = 78.27(1)°, β = 88.89(2)° and γ = 88.60(1)°, Z = 2, R = 0.04 for 3915 independent data; 3: a = 8.449(2), b = 14.622(4), c = 15.809(8)Å, α = 61.84(3)°, β = 73.67(3)° and γ = 78.23(2)°, Z = 2, R = 0.029 for 6585 independent data). Crystals of 4 (M = W) and 5 (M = Mo) are monoclinic, space group P2 1/ m, Z = 2 ( 4: a = 12.296(4), b = 14.794(4), c = 10.260(3)Åand β = 101.88(3)°, R = 0.034 for 4450 independent data; 5: a = 12.306(2), b = 14.809(3), c = 10.257(2)Åand β = 101.99(3)°, R = 0.043 for 3078 independent data). The crystal structure determinations of 4 and 5 show that four edges of the tetrahedral MS 4 2− core are coordinated by copper atoms forming WS 4Cu 4 aggregates linked by eight-membered Cu(NCS) 2Cu rings. A two-dimensional network is thus formed in the diagonal (101) plane. The space between the anionic two-dimensional networks is filled with the NEt 4 + cations. Additional NCS groups lead to the [Cu 4(NCS) 5WS 4] 3− ( 1) trianion connected by NCS bridges forming pseudo-dimers. These latter are held together by weak Cu S(NCS) interactions giving rise to infinite chains along a direction parallel to [100]. In contrast complex 3 develops infinite chains from WS 4Cu 3 aggregates with the same Cu(NCS) 2Cu bridges as in 4 and 5. These chains are running along a direction parallel to [010]. The structural data of the different types of polymeric compounds containing MS 4 2− and CuNCS have been used to interpret vibrational spectroscopic data of the thiocyanate groups.