Nucleophilic Addition of Water and Alcohols to Dicyanonitrosomethanide: Ligands with Diverse Bonding Modes in Magnetically Coupled d-Block Complexes

Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbarnoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu-3(acnm)(2)(dmae)(2)(H2O)(2)] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = -500 cm(-1). [Cu(acnm)(NH3)(2)](infinity) (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 11) chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)(NH3)(2)(py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm)(2)(H2O)(2)] (4) and polymeric {[Cu(cenm)(2)](2)center dot H2O}(infinity) (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. ([Mn-3(ccnm)(2)(EtOH)(2)(OAC)(4)]center dot 2EtOH}(infinity) (6) and (Et4N)(2)[Cu(ccnm)(4)] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm)(3)Mn(bipy)(MeOH)](ClO4) (8) (cmnm = cyano[imino(methoxy)methyl]nitrosomethanide, bipy = 2,2'-bipyricline) displays weak antiferromagnetic coupling between manganese atoms with J = -1.44 cm(-1). A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy)(2)(dcnm)(2)] (9) or [Mn(bipy)(2)(H2O)(dcnm)](dcnm)center dot H2O (10) and [Mn(bipy)(2)(dcnm)(H2O)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm)(2)(H2O)2] (12).