Controlled hydrolysis reactions of the group 15 element-azamacrocyclic complexes MCl(3)L (M=As, Sb or Bi; L equals 1,4,7-trimethyl-1,4,7-triazacyclononane). Formation and crystal structures of [AsCl(2)L][As2OCl5], [H(2)L](2)[Sb2OCl6]Cl-2, [HL]I and [H(2)L](2)[Sb2Cl9]Cl center dot MeCN center dot H2O

Reactions of MCl(3) (M = As, Sb or Bi) and 1,4,7-trimethyl-1,4,7-triazacyclononane (Me(3)[9]aneN(3) = L) gave the respective 1:1 adducts as white-yellow microcrystalline solids which were characterised by microanalytical and spectroscopic (IR and H-1 NMR) data. Addition of water to AsCl(3)L under controlled stoichiometry in acetonitrile solution led to the formation of the white crystalline salt [AsCl(2)L][As2OCl5] 1. A crystal structure determination revealed the cation as five-co-ordinate with psi-octahedral metal geometry featuring a cis-AsCl2+ unit co-ordinated to the three donor nitrogen atoms of the ligand (fac) and a stereochemically active lone pair occupying the sixth site [As-Cl 2.462(7), 2.520(7) and As-N 2.18(2), 2.12(2), 2.10(2) Angstrom with the latter directly opposite to the lone pair]. The anion is made up of a dinuclear (mu-oxo) Cl2As-O-AsCl2 unit with a single Cl- anion linked symmetrically to the two separate arsenic atoms [mean As-Cl-terminal 2.216(8), As-Cl-bridge 2.795(8) Angstrom]. Controlled hydrolysis of SbCl(3)L in acetonitrile solution provided colourless needle crystals of [H(2)L](2)[Sb2OCl6]Cl-2 2 as identified by X-ray diffraction studies. The structure of the dication shows protonation of two of the three nitrogen atoms with strong intramolecular hydrogen bonding N-H ... N 2.70-2.85 Angstrom involving the third amine centre. This is the first structural characterisation of the diprotonated form of L. The structure of the accompanying chlorooxoantimony(III) anion can be described as a single (mu-oxo) Cl2Sb-O-SbCl2 unit linked to two chlorideions via secondary Sb ... Cl bonding involving the two metal centres [mean Sb-Cl-terminal 2.435(3), Sb-Cl-bridge 2.863(3) Angstrom]. Each of the antimony(III) centres is further associated with a unique chloride anion, Sb ... Cl- 3.550(7) Angstrom, which, in turn, forms close contacts with the two protonated nitrogen atoms of the triazamacrocycle Cl ... H-N 3.07, 3.02 Angstrom. Treatment of L and SiMe(3)I in acetonitrile solution provided yellow needle crystals of [HL]I 3. X-Ray (diffraction) crystallographic characterisation revealed a monoprotonated ring (L) in which the single proton is bonded directly to one nitrogen atom and to the remaining two via intramolecular hydrogen bonding N-H ... N 2.71 Angstrom. The product isolated from the reaction of L and SiCl4 in the presence of antimony(v) chloride as halide abstractor in acetonitrile was identified by a crystal structure determination as [H(2)L](2)[Sb2Cl9]Cl . MeCN . H2O 4. The structure reveals two [H(2)L] ... Cl moieties which have dimensions similar to those found for 2. Conformational analyses have been carried out on free L and its mono-, di- and tri-protonated forms and the results are consistent with the experimental conformations observed in this work and elsewhere.