4-[(2-Chlorophenyl)diazenyl]-6-methoxy-2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one.

The structure of the title compound, C(18)H(20)ClN(3)O(5), displays the characteristic features of azobenzene derivatives. Intramolecular N-H.O, weak intramolecular C-H.O, and intermolecular O-H.O and C-H.O interactions influence the conformation of the molecules and the crystal packing. Intermolecular hydrogen bonds link the molecules into infinite chains, and the title compound adopts the keto-amine tautomeric form. The azobenzene moiety of the molecule has a trans configuration. The molecule is not planar, and the dihedral angle between the two phenyl rings is 35.6 (2) degrees.

Organometallic Selenolates. 5.(1) Synthesis and Complexing Properties of 2-Propene- and 2-Methyl-2-propeneselenolato Molybdenum and Tungsten Compounds. Crystal Structures of cp(CO)(3)WSeCH(2)C(CH(3))=CH(2), [cp(CO)(2)MoSeCH(2)C(CH(3))=CH(2)](2), [cp(CO)(3)Mo(&mgr;-SeCH(2)C(CH(3))=CH(2))W(CO)(5)], [cp(CO)(3)Mo(&mgr;-SeCH(2)C(CH(3))=CH(2))Mo(CO)(5)], and [cp(CO)(3)Mo(&mgr;-SeCH(2)CH=CH(2))Mo(CO)(5)].

2-Propene- and 2-methyl-2-propeneselenolato complexes of molybdenum(II) and tungsten(II) have been prepared via insertion of gray selenium into alkali-metal-molybdenum and -tungsten bonds and subsequent reaction with allyl and beta-methallyl chlorides. The complexes are monomeric in the solid state. The (beta-methallyl)molybdenum compound cp(CO)(3)MoSeCH(2)C(CH(3))=CH(2) (2) decomposes slowly in solution with CO loss and formation of the corresponding dimer [cp(CO)(2)MoSeCH(2)C(CH(3))=CH(2)](2) (3), whose crystal structure has been determined (C(22)H(24)Mo(2)O(4)Se(2), monoclinic, P2(1)/c, a = 11.151(2) Å, b = 13.436(3) Å, c = 16.872(3) Å, beta = 102.42(2) degrees, Z = 4). A monomeric structure has been found for cp(CO)(3)WSeCH(2)C(CH(3))=CH(2) (5) (C(12)H(12)O(3)SeW, triclinic, P&onemacr;, a = 7.592(3) Å, b = 7.700(3) Å, c = 12.296(5) Å, alpha = 98.31(4) degrees, beta = 104.24(2) degrees, gamma = 108.49(3) degrees, Z = 2). Additionally, the complexing properties of the selenolato complexes have been investigated. The reactions of the molybdenum complexes cp(CO)(3)MoSeCH(2)CH=CH(2) (1) and (2) with the metal(0)-carbonyl complexes W(CO)(5)(THF), (CH(3)CN)(3)Mo(CO)(3), and (eta(6)-C(7)H(8))Mo(CO)(3) (C(7)H(8) = cycloheptatriene) led to the formation of [cp(CO)(3)Mo(&mgr;-SeCH(2)C(CH(3))=CH(2))M(CO)(5)] (M = W (6), Mo (7)) and [cp(CO)(3)Mo(&mgr;-SeCH(2)CH=CH(2))Mo(CO)(5)] (8), respectively. 6 and 7 are isostructural and crystallize in the monoclinic space group P2(1)/n (6, C(17)H(12)MoO(8)SeW, a = 14.708(2) Å, b = 9.837(2) Å, c = 14.958(2) Å, beta = 103.030(10) degrees, Z = 4; 7, C(17)H(12)Mo(2)O(8)Se, a = 14.712(2) Å, b = 9.8670(10) Å, c = 14.982(2) Å, beta = 103.100(10) degrees, Z = 4), whereas [cp(CO)(3)Mo(&mgr;-SeCH(2)CH=CH(2))Mo(CO)(5)] (8) crystallizes in the noncentrosymmetric orthorhombic space group Pna2(1) (C(16)H(10)Mo(2)O(8)Se, a = 18.638(4) Å, b = 9.707(2) Å, c = 11.169(3) Å, Z = 4). Furthermore, (77)Se-NMR spectra displayed chemical shifts consistent with earlier results on related complexes.

Coordination Chemistry of 2,2'-Dipyridyl Diselenide: X-ray Crystal Structures of PySeSePy, [Zn(PySeSePy)Cl(2)], [(PySeSePy)Hg(C(6)F(5))(2)], [Mo(SePy)(2)(CO)(3)], [W(SePy)(2)(CO)(3)], and [Fe(SePy)(2)(CO)(2)] (PySeSePy = C(5)H(4)NSeSeC(5)H(4)N; SePy = [C(5)H(4)N(2-Se)-N,Se]).

The coordination chemistry of 2,2'-dipyridyl diselenide (PySeSePy) (2) (C(10)H(8)N(2)Se(2)) has been investigated and its crystal structure has been determined (monoclinic, P2(1)/c, a = 10.129(2) Å, b = 5.7332(12) Å, c = 19.173(3) Å, beta = 101.493(8) degrees, Z = 4). In metal complexes the ligand was found to coordinate in three different modes, as also confirmed by X-ray structure determination. N,N'-coordination was found in the zinc complex [Zn(PySeSePy)Cl(2)] (3) (C(10)H(8)Cl(2)N(2)Se(2)Zn, triclinic, P&onemacr;, a = 7.9430(10) Å, b = 8.147(2) Å, c = 11.999(2) Å, alpha = 93.685(10) degrees, beta = 107.763(10) degrees, gamma = 115.440(10) degrees, Z = 2) and Se,Se'-coordination in the adduct of the ligand with bis(pentafluorophenyl)mercury(II) [PySeSePyHg(C(6)F(5))(2)] (5) (C(10)H(8)F(10)HgN(2)Se(2), monoclinic, P2(1)/n, a = 7.7325(10) Å, b = 5.9974(14) Å, c = 25.573, beta = 98.037(10) degrees, Z = 2), which however displays only weak interactions between selenium and mercury. The reaction of the ligand with norbornadiene carbonyl complexes of molybdenum and tungsten leads to reductive cleavage of the selenium-selenium bond with oxidation of the metal center and concomitant addition of the resulting selenolate to the metal carbonyl fragment. Thus the 7-coordinate complexes [Mo(SePy)(2)(CO)(3)] (6) (C(13)H(8)MoN(2)O(3)Se(2), monoclinic, P2(1)/n, a = 9.319(3) Å, b = 12.886(5) Å, c = 13.231(6) Å, beta = 109.23(3) degrees, Z = 4) and [W(SePy)(2)(CO)(3)] (7) (C(13)H(8)N(2)O(3)Se(2)W, monoclinic, P2(1)/n, a = 9.303(2) Å, b = 12.853(2) Å, c = 13.232(2) Å, beta = 109.270(10) degrees, Z = 4) were obtained. The same N,Se-coordination pattern emerges from the reaction of [Fe(2)(CO)(9)] with (2) leading to [Fe(SePy)(2)(CO)(2)] (8) (C(12)H(8)FeN(2)O(2)Se(2), monoclinic, P&onemacr;, a = 8.6691(14) Å, b = 12.443(2) Å, c = 14.085(2) Å, alpha = 105.811(10) degrees, beta = 107.533(8) degrees, gamma = 92.075(10) degrees, Z = 4).