(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

Abstract

(1) and (2), no significant influence on the molecular structure within the coordination sphere is detected. In both compounds, the Co atom is half-way between the planes of the four-and five-membered coordinated rings. The cyclobutadiene ring is slightly contracted along the diagonal between the phenylsubstituted C atoms.lntroduetlon. In previous work (Brune & Horlbeck, 1973) the influence of substituents on the phenyl rings on the bonding properties and structures of tricarbonyl-(1,2-diphenylcyclobutadiene)iron(III) complexes were studied with NMR. The observation and interpretation 0108-2701/87/020221-04501.50 of different nuclear spin-spin coupling constants lead to the conclusion that significant modifications of the molecular geometry of the four-membered ring and its bonding to the central atom with change of electronic character of the substituents occur. To observe these changes directly, the crystal structure analysis was undertaken of both title compounds whose phenyl rings are substituted with a methoxy group in (1) as a strong ~r-donating substituent and the trifluoromethyl group in (2) as an efficient inductive a-attracting one.Experimental. Crystals of both title compounds are red-brown; (1) crystallizes in the form of elongated parallelepipeds, (2) in the form of octahedra, both with well developed faces. (1) Crystal 0.2 x 0.2 x 0.4mm; (2) crystal 0.2 x 0.1 x 0.3mm. 4914 (1) and 5643 (2) independent unique reflections; Philips PW 1100 four-circle diffractometer; Mo Ka radiation, graphite monochromator; 0-20 scan, 3188 observed reflections for (1) [F > 1.5a(F), -26 < h < 25, 0 < k < 10, 0 < l < 16, 0mi n = 2, /~max = 25°] and 3955 observed reflections for (2) [F > 1.5e(F), -21 < h < 21, 0 < k < 16, 0 < l < 15, 0m~, = 2, Omax = 25°]" The intensity of three standards did not vary during the period of measurement. The cell parameters were

Toward a Square-Grid Polymer: Synthesis and Structure of Pedestal-Mounted Tetragonal Star Connectors, C4R4−Co−C5Y5

“…Although some related organometallic complexes suitable for use as star connectors have been synthesized recently, and although a fair number of derivatives of 1 are known, none can serve immediately as the desired module. First, only a few complexes with phenyl rings substituted in the para position are known, , and they do not have proper functionalities to serve a linear couplers. Second, most of the previously characterized Cp-substituted derivatives carry only one, two, or three substituents on the ring.…”