On the structure and water content of copper(II) tricyanomethanide

Abstract

INTEREST has recently been revived in tricyanomethane, CH(CN) 3, and related compounds1-*. Salts of MnII, FeII, CoII, NiII, and CuII have been prepared and some of their properties investigated.7 On the basis of their electronic and infrared spectra a polymeric model for their structure has been proposed by Enemark and Holm7. Doubt remains, however, as to whether or not water is present in some of these salts. Enemark and Holm state that FeII and CoII tricyanomethanides retain half a molecule of water per metal atom, that the NiII compound can be prepared with a variable amount of water, and that the MnII and CuII salts retain one fourth of a molecule of water. On the other hand, the model proposed by these same Authors for the structure of these compounds "does not take into account the small amounts of water present"'. It should also be noted that in a previous paper3 the MnII and CuII salts were stated to be anhydrous.In order to substantiate the proposed structure and to find how water, if any, is co-ordinated, the X-ray crystal structure of the copper salt, Cu[C-(CX) 3] 2, was determined. Additional experiments relating to the suspected presence of water were carried out by thermogravimetric and differential thermal analysis. Samples were prepared both according to the directions of Enemark and Holm7 and by diffusiong. Debye-Scherrer diffraction patterns of powdered crystals prepared by the two different methods are identical.Crystal data listed below were collected, and the three-dimensional X-ray analysis described was performed, using crystals prepared by diffusion. These are black, yellow when powdered, crystallize in the orthorombic system; a = 7.176 & 0.005,

Synthesis, single-crystal structure determination and Raman spectrum of Cu[C(CN)3]2·2 NH3

“…Nevertheless, compared to previously reported structural data, our structure refinements for Ag [tcm] and Cu[tcm] 2 are of better [4,20] or at least comparable quality [5,21].…”

“…3). All bond lengths and angles are in a familiar and expected range (Table 3); only d(Cu-N 2 ) = 242.9(2) pm is a little longer than the other four Cu-N bonds, but this pattern is also found in Cu[tcm] 2 [d(Cu-N) = 247.1(3) pm] [4,5]. Each [tcm] anion coordinates two Cu cations, therefore, chains are formed (Fig.…”

“…The crystal structures of Cu[tcm] 2 [4,5] and Ag[tcm] [20,21] have already been discussed in detail, so we omit another discussion here, since these compounds were synthesized for three purposes: as educts, for comparison and to gather their Raman spectra. Nevertheless, compared to previously reported structural data, our structure refinements for Ag [tcm] and Cu[tcm] 2 are of better [4,20] or at least comparable quality [5,21].…”

“…Divalent copper in combination with small anionic moieties such as cyanamide in Cu[CN 2 ] [1], dicyanamide (dca) in Cu[N(CN) 2 ] 2 [2,3] or tricyanmethanide in Cu[C(CN) 3 ] 2 [4,5] (from now on denoted as '[tcm]') was the object of intensive research since unusual magnetic properties were expected, but only for Cu [CN 2 ] has this been found to be true [6][7][8][9]. This was also the only compound where the strong affinity of Cu 2+ for ammonia has been used for exploring the reaction pathways and to explore related ammoniakate compounds.…”

Structure of trans-M(CO)(C4N3)(PPh3)2.1.5C6H6 (M = Ir and Rh): the pyramidal geometry of the tricyanomethanide anion (C4N3 −)

“…The crystal structure of (1) has been studied (Witt, 1973;Wang, 1987) and it was observed that one of the cyano groups has unusually large displacement parameters. In previous structural studies of TCM complexes, TCM served either as a bridging ligand (Konnert & Britton, 1966;Biondi, Bonamico, Torelli & Vaciage, 1965;Chow & Britton, 1975;Summerville, Cohen, Hatano & Scheidt, 1978;Britton & Chow, 1983) or as an uncoordinated anion (Baukova, Kravtsov, Kuz'mina, Dvortsova, PorayKoshits & Perevalova, 1989). Details of the structures of the monomeric TCM-transition-metal complexes have not been reported.…”