ReactionwithDihydrogenandPrimarySilanes t e t r a h~d r o f~~~a n , a n d~h = p h e n r l } ( l~) t o ZrCl,(THT), ( T H T = t e t r a h~d r o t h~o -

The osmium tetroxide-mediated dihydroxylation of meso-tetraphenylporphyrin leads to the formation of the vic-diol meso-tetraphenyl-2,3-vic-diol-2,3-chlorin. The corresponding Ni(II) complex was converted by lead tetraacetate into (meso-tetraphenyl-2,3-secochlorinato-2,3-dialdehyde)nickel(II). This novel pigment undergoes an almost quantitative, intramolecular double acetal formation when treated with methanol in the presence of acid to produce a porphyrinoid in which one pyrrolic unit is formally replaced by a six-membered ring. An X-ray crystal structure determination, the first for such a homoporphyrin, reveals the severely twisted conformation of its chromophore.

The salts [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, are prepared by reductive carbonylation of Pd[Pd(SO(3)F)(6)], Pt(SO(3)F)(4) or PtF(6) in liquid SbF(5), or HF-SbF(5). The resulting moisture-sensitive, colorless solids are thermally stable up to 140 degrees C (M = Pd) or 200 degrees C (M = Pt). Their thermal decompositions are studied by differential scanning calorimetry (DSC). Single crystals of both salts are suitable for an X-ray diffraction study at 180 K. Both isostructural salts crystallize in the monoclinic space group P2(1)/c (No. 14). The unit cell volume of [Pt(CO)(4)][Sb(2)F(11)](2) is smaller than that of [Pd(CO)(4)][Sb(2)F(11)](2) by about 0.4%. The cations [M(CO)(4)](2+), M = Pd, Pt, are square planar with only very slight angular and out-of-plane deviations from D(4)(h)() symmetry. The interatomic distances and bond angles for both cations are essentially identical. The [Sb(2)F(11)](-) anions in [M(CO)(4)][Sb(2)F(11)](2,) M = Pd, Pt, are not symmetry-related, and both pairs differ in their Sb-F-Sb bridge angles and their dihedral angles. There are in each salt four to five secondary interionic C- -F contacts per CO group. Of these, two contacts per CO group are significantly shorter than the sum of the van der Waals radii by 0.58 - 0.37 A. In addition, structural, and spectroscopic details of recently synthesized [Rh(CO)(4)][Al(2)Cl(7)] are reported. The cations [Rh(CO)(4)](+) and [M(CO)(4)](2+), M = Pd, Pt, are characterized by IR and Raman spectroscopy. Of the 16 vibrational modes (13 observable, 3 inactive) 10 (Pd, Pt) or 9 (Rh), respectively, are found experimentally. The vibrational assignments are supported by DFT calculations, which provide in addition to band positions also intensities of IR bands and Raman signals as well as internal force constants for the cations. (13)C NMR measurements complete the characterization of the square planar metal carbonyl cations. The extensive characterization of [M(CO)(4)][Sb(2)F(11)](2), M = Pd, Pt, reported here, allows a comparison to linear and octahedral [M(CO)(n)()][Sb(2)F(11)](2) salts [M = Hg (n = 2); Fe, Ru, Os (n = 6)] and their derivatives, which permit a deeper understanding of M-CO bonding in the solid state for superelectrophilic cations with [Sb(2)F(11)](-) or [SbF(6)](-) as anions.

meso-Phenyldipyrromethanes can be oxidized by 2,6-dicyano-3,5-dichloro-para-benzoquinone (DDQ) to the corresponding meso-phenyldipyrrins. As expected, these novel, stable bipyrrolic pigments readily form metal chelates with copper(II), nickel(II), and zinc(I1). Their UV-VIS spectra are compared with a series of known alkyl-substituted dipyrrin chelates and, based on the UV-VIS spectral analysis, the dihedral angle between the two ligands in the bis[mesophenyldipyrrinato]Ni(II) complex was calculated to be 42". The molecular structure of this complex was determined by X-ray crystallography, essentially confirming the calculation. Crystals of C3,H2,N4Ni are orthorhombic, a = 17.156(3), b = 35.217(1), c = 7.886(1) A, Z = 8, space group Fddd. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.040 and R,, = 0.031 for 1058 reflections with I 2 ~u(F,). The central nickel is coordinated in a distorted square-planar fashion by four nitrogens. The pair of the planar dipymnato ligands enclose a dihedral angle of 38.5". This is the lowest angle reported for nickel(I1) complexes of this kind. As a result of this, and in sharp contrast to previously described nickel(I1) dipyrrin chelates, the central metal is diamagnetic.Key words: meso-phenyldipyrromethanes, meso-phenyldipymns, meso-phenyldipyrrinato transition metal chelates, X-ray crystallography.Resume : Sous l'influence de la 2,6-dicyano-3,5-dichloro-para-benzoquinone (DDQ), on peut oxyder les mksophCnyldipyrromCthanes en mkso-phCnyldipymnes correspondantes. Comme on pouvait s'y attendre, ces nouveaux pigments bipyrroliques stables forment des chClates mktalliques avec le cuivre(II), le nickel(I1) et le zinc(I1). On a comparC leurs spectres UV-VIS avec ceux d'une sCrie de chClates connus de dipymnes substitutkes par des groupes alkyles et, sur la base d'une analyse des spectres UV-VIS, on a calculC que l'angle dikdre entre les deux coordinats du complexe bis[miso-phCnyldipyrrinato]Ni(II) est de 42". La structure molCculaire de ce complexe, telle que dCterminCe par diffraction des rayons X, confirme essentiellement les conclusions obtenues par calculs. Les cristaux du C3&,,N4Ni sont orthorhombiques, groupe d'espace Fddd, avec a Le nickel central est coordinC d'une faqon plan carrC dCformCe par les quatre azotes. La paire de coordinats dipymnato plans forme un angle dikdrdre de 38,5". Cette valeur correspond h l'angle le plus faible rapport6 pour des complexes de nickel(II1) de cette espbce. I1 en rCsulte que, par opposition h ce qui a Ct C dCcrit anterieurement pour les chClates de nickel(I1) dipymne, le mCtal central est diamagnktique.