Crystal structural studies of bis(biguanide)nickel(II) chloride

Abstract

SamunaryEvidence is presented for a new structure for bis(biguanide)nickel( 11) chloride.THE structure of four-co-ordinated metal biguanide complexes has long been a topic of controversy among several research groups. Ray and Sahal have considered a variety of structures for the biguanide complexes and have cited evidence in support of structure (I). Kunchur and Mathew2 have reported a single crystal X-ray diffraction study in which they state that they have confirmed the structure suggested by Ray and Saha for a substituted biguanide complex, ethylenebis(biguanide)copper( I I) chloride monohydrate. We report a single crystal X-ray diffraction study of bis(biguanide)nickel( 11) chloride dihydrate and a lH n.m.r. study of anhydrous bis(biguanide)nickel( I I ) chloride, which provide the first definite evidence favouring the alternative structure (11) for a complex of this type. The structure of bis(biguanide)nickel( 11) chloride dihydrate has been solved by single-crystal X-ray diffraction techniques with visually estimated Weissenberg intensity data for 848 diffraction maxima. The data were refined by a block diagonal isotropic least-square procedure to a conventional R-factor of 12.3%. Crystals of the complex are triclinic, space group P 1, a = 6.85 -& 0.02,

Structural researches on the chelating behaviour of the biguanide ligand. The crystal structures of Co(C2H6N5)3 � 2H2O and Cu(C2H7N5)2CO3�4H20

“…Scheme 2 includes reactions of piperidine, n-butylamine and pyridine with the chlorobis(salicylato)iron(lll) complex, FeCI(o-HOC6H4CO2)2 -1420 , (6). Analytical results are given in Table 1 and important i.r.…”

“…In particular, it is noteworthy that the behaviour of HBG, which in the free state gives crystals containing an unsymmetrical tautomeric form (1)(5), assumes symmetrical tautomeric forms when coordinated to a metal, which are either deprotonated (2) (4) or neutral (3) (6)(7). This last behaviour is uniquely observed in the AEBG and EBG metal complexes (4).…”

Comparison of an OD and an ordered structure of nickel and copper malondiamidine complexes

“…In the metal complexes, the N-C distances become slightly unequal, as in the more stable Ni biguanide complex (Creitz, Gsell & Wampler, 1969). The relative instability of the malondiamidine complex in aqueous solution could be due to the more symmetrical free ligand.…”

“…The structures of neutral, mono-and diprotonated biguanide, C2H7N5, (Pinkerton & Schwarzenbach, 1977;Ernst & Cagle, 1977;Ernst, 1977) and of the square-planar complex of biguanide with Ni II (Creitz, Gsell & Wampler, 1969) show that in each case the n electrons are delocalized over the whole molecule. The protonated forms are not planar, because of steric hindrance, but all atoms have approximate trigonal (2),]~ = 92.12 (2) 2 D O = 1.87, D c = 1.91 2/m 18.0 0.11 to 0.30 Between 1.182 and 1.268 0-8586 2 quadrants to sin 0/2 = 0.7, 0.016 2064 83 0-036 symmetry indicating sp 2 hybridization.…”

The crystal and molecular structure of tris(biguanidato)chromium(III) monohydrate

“…Biguanide (BG) and its substituted derivatives ethylenebisbiguanide (EBG) or 2-aminoethylbiguanide (AEBG) are interesting ligands which form highly coloured complexes with many transition metals, the fol-lowing X-ray determinations of which have already been reported: Ni(BG)2CI2 (Creitz, Gsell & Wampler, 1969), Cr(BG)3-d-10-camphorsulphonic acid.3H20 (Brubaker & Webb, 1969), Co(BG)3C13.H20 (Snow, 1974), Cu(EBG)C12. H20 (Mathew & Kunchur, 1970), Ni(EBG)C12.…”