Crystal structures and spectroscopic characterization of MBr2(CNXyl) n (M = Fe and Co, n = 4; M = Ni, n = 2; Xyl = 2,6-dimethylphenyl), and of formally zero-valent iron as a cocrystal of Fe(CNXyl)5 and Fe2(CNXyl)9

Structures and spectroscopic characterization of the divalent complexes cis-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II) dichloromethane 0.771-solvate, [FeBr2(C9H9N)4]·0.771CH2Cl2 or cis-FeBr2(CNXyl)4·0.771CH2Cl2 (Xyl = 2,6-dimethylphenyl), trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II), [FeBr2(C9H9N)4] or trans-FeBr2(CNXyl)4, trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)cobalt(II), [CoBr2(C9H9N)4] or trans-CoBr2(CNXyl)4, and trans-dibromidobis(2,6-dimethylphenyl isocyanide)nickel(II), [NiBr2(C9H9N)2] or trans-NiBr2(CNXyl)2, are presented. Additionally, crystals grown from a cold diethyl ether solution of zero-valent Fe(CNXyl)5 produced a structure containing a cocrystallization of mononuclear Fe(CNXyl)5 and the previously unknown dinuclear [Fe(CNXyl)3]2(μ2-CNXyl)3, namely pentakis(2,6-dimethylphenyl isocyanide)iron(0) tris(μ2-2,6-dimethylphenyl isocyanide)bis[tris(2,6-dimethylphenyl isocyanide)iron(0)], [Fe(C9H9N)5][Fe2(C9H9N)9]. The (M)C—N—C(Xyl) angles of the isocyanide ligand are nearly linear for the metals in the +2 oxidation state, for which the ligands function essentially as pure donors. The νCN stretching frequencies for these divalent metal isocyanides are at or above that of the free ligand. Relative to FeII, in the structure containing iron in the formally zero-valent oxidation state, the Fe—C bond lengths have shortened, the C[triple-bond]N bond lengths have elongated, the (M)C—N—C(Xyl) angles of the terminal CNXyl ligands are more bent, and the νCN stretching frequencies have shifted to lower energies, all indicative of substantial M(dπ)→π* backbonding.

ANTINEOPLASTIC AGENTS: XV. INTRAMOLECULAR REACTIONS OF N-PHENYL-N′-BIS(2-CHLOROETHYL)UREA

Reaction between phenyl isocyanate and N-bis(2-chloroethyl)amine in cold diethyl ether solution yields N-phenyl-N′-bis(2-chloroethyl)urea. The urea was found to rearrange in ethanol solution or upon warming to, respectively, 2-(N-phenylimino)-3-(2′-chloroethyl)oxazolidine hydrochloride and 1-phenyl-2-oxo-3-(2′-chloroethyl)imidazolidine. Infrared spectral studies, augmented by mass and proton magnetic resonance determinations provided compelling support for the structural formulations. The oxazolidine reaction sequence was also examined employing 4-nitrophenyl isocyanate, 1-naphthyl isocyanate, and N-bis(2-bromoethyl)amine.