L- thiourea

Various thiourea ligands have been used in the synthesis of mixed ligand complexes. A series of complexes [NiQ2L2] (HQ = ethylacetoacetate, L = thiourea, allyl-, benzoyl-, methyl-, diphenyl-thiourea) have been prepared. The complexes are all paramagnetic (/i = 3.02-3.27/iB) and have been assigned tra 5-octahedral structures.1014... 

The crystal structure of the dithioacetylacetone (sacsacH) complex of cobalt(n), Co(sacsac)2, shows it to be monomeric square planar,164 in marked contrast to the acacH analogue. Pyridine 2-thiol (LH), which can exist as the thione tautomer (31) forms Co(LH)2X2 (X = Cl, Br, or I) complexes these contain the ligand bonded through the sulphur, as evidenced by the presence of a v(N—H) vibration in the i.r. spectra.165 Morpholine 4-thiocarbonic acid (32) also appears to be S-bonded in the CoL2X2 complexes (X = Cl, Br, or I), since the v(C=S) frequency is lowered upon co-ordination.166 The electronic spectra of the CoL2C12 complexes (L = thiourea, A-phenylthiourea, and TViV -diphenylthiourea) have been recorded.167... 

The thiourea complexes (CdL6)(C104)2 have been prepared131 [L = thiourea or RNHC(S)NHPh, R = Me, Ph, m- and p-MeC6H4, or a-naphthyl]. Their i.r. spectra show them to be S-bonded. 

Thiourea is known to form a series of complexes HgCl2Lrt (n = 1 — 4, L = thiourea). Structural studies on the complexes n = 2 or 4 have now been reported. The crystal structure of HgCl2L2187 shows the mercury to be co-ordinated in a distorted trigonal coplanar conformation by two equivalent thiourea sulphur atoms (Hg—S = 2-42 A) and a chlorine atom (Fig—Cl = 2.57 A). The other ionic chlorine atom lies normal to this plane, between and equidistant from a pair of mercury atoms (Hg—Cl = 3.22 A). 

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