www.elsevier.nl/locate/jorganchem Journal of Organometallic Chemistry 593 – 594 (2000) 161 – 166 Crystal and molecular structures of 4,4-bis(dimethylhydroxysilyl)-biphenyl and m -bis(dimethylhydroxysilyl)benzene David M.L. Goodgame *, Paul D. Lickiss, Stephan Menzer, Stephanie J. Rooke, David J. Williams Chemistry Department, Imperial College of Science, Technology and Medicine, London SW 72AY, UK Received 29 May 1999; accepted 8 July 1999 We dedicate this paper to Professor Fausto Calderazzo to mark the occasion of his 70th birthday. Abstract The crystal structures of 4,4-bis-(dimethylhydroxysilyl)biphenyl (1) and m-bis(dimethylhydroxysilyl)benzene (2) are reported. Crystals of (1) are monoclinic, P 2 1 /n, with a 9.970(2), b 7.185(1), c 24.134(2) A  ,  98.795(8)°, and Z 4. Crystals of (2) are monoclinic, P 2 1 /n, with a 5.960(1), b 24.205(10), c 18.635(9) A  ,  97.14(1)°, and Z 8. In compound 1, a combination of OH···O hydrogen bonds and CH··· interactions results in the formation of sheets of enantiomeric pairs of helices, and these sheets are linked by additional CH··· interactions into a continuous three-dimensional network. In compound 2 both OH···O hydrogen bonds and CH··· interactions are also present but, in this case, hexagonal arrays of stacks of molecular dimers are formed. © 2000 Elsevier Science S.A. All rights reserved. Keywords: Crystal structure; Silanol; Hydrogen bonding 1. Introduction We have recently shown that ‘extended reach’ O- donor ligands comprising pairs of lactams [1], pyri- dones [2] or amide groups [3] connected by lengthy spacer units are very effective at generating novel poly- meric array structures with a wide range of metal ions. We are now extending this work to involve spacer- linked bis-silanols as precursors for the bridging groups. Attractive candidates for this include 4,4-bis(- dimethylhydroxysilyl)biphenyl, 1, m -bis(dimethylhy- droxysilyl)benzene, 2, and its para -analogue, 3. As well as the preferred metal coordination geome- try, the various factors influencing the types of net- works formed by metal complexes with extended-reach ligands include, inter alia, the conformational prefer- ences of those ligands, the presence of - interactions, and/or hydrogen bond formation. For this reason it is desirable to examine such features in the structures of the metal-free precursor molecules as a guide in the design of the metal-linked products that might be ob- tained from them. The solid state structure of 3, which has been used as a precursor to polysiloxanes containing aryl spacers [4,5], is already known [6]. It forms a complicated hydrogen bonded arrangement of three independent molecules, two of which hydrogen bond to form chains whilst the third serves as a linker between these chains so as to give a three-dimensional network. Although compounds 1 and 2 are both already known [4,5,7] their structures do not appear to have been reported. We report here the results of single-crystal X-ray stud- ies on both 1 and 2. 2. Results and discussion 2.1. Structure of 4,4 -bis(dimethylhydroxysilyl)biphenyl (1) Initially, perhaps the most surprising feature of the structure adopted by compound 1 in the solid state is * Corresponding author. 0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved. PII:S0022-328X(99)00395-2